[0001] This invention relates to aerosol cans of the type which house a piston slidable
along the axis of the can and which contain a viscous product. More particularly,
this invention relates to an improved method of filling an aerosol can having a piston
slidable along the axis of the can with a viscous product.
[0002] Aerosol cans or containers which have a piston slidable along the axis of the can
have been used for many years for dispensing viscous products such as cheese spreads
and toothpaste. The product to be dispensed occupies the region within the can above
the piston and a pressurized fluid, usually air, occupies the region below the piston.
When the valve at the top of the can is manipulated to open it, the pressurized fluid
is able to push the piston toward the top of the can, and the piston in turn pushes
some of the viscous product out of the can through the valve. Aerosol cans of this
type are discussed in U.S. Patent No. 3,897,672 to Scheindel.
[0003] The prior art has faced many problems in connection with filling such a can with
the viscous product to be dispensed.
[0004] The prior art methods for dispensing a viscous product into the can required expensive
equipment and was relatively slow. One such prior art method comprises inserting a
tubular dispensing member into the can with its discharge end positioned near the
piston (which would be at its lowermost position near the bottom of the can) at the
commencement of filling. The diameter of the tubular dispensing member is substantially
less than the diameter of the hole in the top wall of the can through which it is
inserted. Viscous product is pumped through the tubular dispensing member and as viscous
product flows out of the tubular member into the can, the can is lowered as the viscous
product is introduced into the can. Alternately, the tubular dispensing member may
be retracted from the can as the viscous product is introduced into the can. This
alternate prior art method of filling the can with viscous material is discussed in
U.S. Patent No. 3,897,672 in conjunction with Fig. 1 of that patent.
[0005] In either of these prior art methods for dispensing the viscous product into the
can, expensive equipment was necessary for either lowering the can or withdrawing
the tubular dispensing member from the can. As previously discussed, these prior art
methods were relatively slow which is disadvantageous in automated can filling operations.
[0006] The prior art methods for dispensing viscous products into a can commenced with the
nozzle or discharge end of the tubular dispensing member positioned near the piston
at the bottom of the can in an attempt to try to fill the region above the piston
with the viscous product. In practice, air spaces or voids usually remained in the
region of the surface of the piston, particularly near the outer periphery or margin
of the piston adjacent the side walls of the can. This created the following problem
in the prior art.
[0007] As discussed in U.S. Patent No. 3,897,672, cans of this type usually have a longitudinally
extending seam. In a seamed can, the internal' periphery of the can is not perfectly
circular because the seam projects into the can. The piston is a hollow and thin-walled
member and is formed of a flexible material such as a suitable plastic. However, the
piston will not conform exactly to the internal shape of the can in the vicinity of
this seam. A small space will remain between the piston side surface and the can interior
surface on each side of the seam.
[0008] The top of the piston is generally shaped somewhat like a truncated cone so as to
generally conform to the top wall of the aerosol can. The prior art viscous product
filling methods typically left voids or air spaces in the region of the outer periphery
or margin of the piston. Upon completion of the filling of the can, an air space usually
also remained above the product at the top of the can, particularly in the region
near the side walls of the can. As a result, when the can is laid on its side for
a considerable amount of time [a condition which is not unusual in normal handling
of the can], the viscous product has an opportunity to settle into these air spaces
thereby leaving a channel or air space running along the entire length of the can
between the piston and the top of the can where the valve is located.
[0009] If the can is now picked up and used, opening the valve permits the pressurized air
to flow from beneath the piston through the spaces between the piston sidewall and
the can wall on each side of the seam, through the channel alongside the product,
and out through the valve. The pressure beneath the piston is therefore reduced and
the ability of the piston to push the product out of the can is greatly hindered or
eliminated. Therefore, some or all of the viscous product can never be dispensed from
the can. Any product which cannot be dispersed is wasted.
[0010] In order to eliminate this prior art problem, U.S. Patent Ho. 3,897,672 proposed
to apply a vacuum to a hole located at the bottom of the can after the can had been
filled with viscous product. The vacuum would draw the viscous product toward the
top of the piston upper surface area and between the piston outer periphery and the
side walls of the can in order to fill any voids between the product and the piston.
[0011] Although the vacuum drawing method of U.S. Patent No. 3,997,672 is successful in
substantially eliminating voids or air spaces between the piston and viscous product,
this vacuum drawing method is relatively slow. The relative slowness is disadvantageous
in automated can filling operations. The use of vacuum is very limiting in high speed
filling operations.
[0012] Another disadvantage of the hereinbefore discussed prior art methods of introducing
a viscous product into a can by either lowering the can or alternately withdrawing
the tubular dispensing member from the can as the viscous product is being introduced
into the can is that the viscous product upper surface has a cone shaped configuration
after the can has been filled. This is illustrated, e.g., in Fig. 1 of U.S. Patent
No. 3,897,672. After the viscous product is dispensed into the can, a valve assembly
is seated on the edge surrounding the top wall opening of the can but is not fastened
to the can. The piston is then moved upwardly in the can by applying compressed air
to the hole at the bottom of the can. Upward movement of the piston forces the viscous
product upward in the can and expels air remaining in the can above the upper surface
of the viscous product. The air flows out the top opening of the can between the edge
on which the valve assembly is seated and the valve assembly. The viscous product
is not forced out of the can.
[0013] Due to the cone shaped configuration of the viscous product resulting from the prior
art methods of introducing the viscous product into the can, air will remain trapped
between the upper surface of the viscous product and the top of the can in the region
of the can near the sidewalls. This trapped air results in undesirable "foaming" or
"sputtering"of the viscous product when it is dispensed from the can.
[0014] Another disadvantage of prior art can filling operations is as follows. When the
piston is moved upward in the can in order to expel air remaining between the top
of the can and the viscous product, the valve assembly must be restrained within the
top wall opening of the can. After the air is expelled, the can is moved to a crimping
station for fastening of the valve assembly to the top edge of the can in an airtight
manner. Although the valve assembly was restrained within the top wall of the can
at the work station where the piston was moved upward and the air expelled, the prior
art does not restrain the valve assembly when the can is being transported from the
piston moving station to the crimping station. Accordingly, if there is any residual
pressure remaining in the can during the transport of the can from the piston moving
station to the valve assembly crimping station, the-residual pressure could cause
the valve assembly to become misaligned with respect to the opening in top wall of
the can while the can is being transported. This misalignment of the valve assembly
during transport of the can to the crimping station results in a disadvantageous relatively
high rejection of cans due to improper crimping of the valve assembly to the can edge
on which the valve assembly was seated. In addition, jamming may occur at the crimping
station which will require stopping the prodiction process while the jam is being
cleared.
[0015] It is therefore an object of the present invention to provide an improved method
of filling a piston-type aerosol can with a viscous product.
[0016] It is another object of the present invention to provide a method for dispensing
a viscous product into a piston-type aerosol can which is relatively fast in comparison
with prior art methods and which eliminates expensive equipment for moving the can
to be filled and a tubular dispensing member relative to each other during the dispensing
of the viscous product into the can.
[0017] It is yet another object of the present invention to provide an improved method for
eliminating air spaces or voida between a viscous product and a piston in a piston-type
aerosol can.
[0018] It is still another object of the present invention to avoid the use of a relatively
slow vacuum step in order to eliminate air spaces and voids between a viscous product
and a piston in a piston-type aerosol can.
[0019] It is a further object of the present invention to provide an improved method of
filling a piston-type aerosol can wherein air spaces or voids located between the
upper surface of a viscous product which has been introduced into the can and the
top wall of the can in the region near the side walls of the aerosol can may be substantially
eliminated.
[0020] It is yet a further object of the present invention to provide an improved nozzle
for the introduction of a viscous product into a piston-type aerosol can.
[0021] It is still a further object of the present invention to provide a method and means
for filling a piston-type aerosol can with a viscous product wherein a valve assembly
seated on an edge member surrounding a top wall opening of the can is substantially
prevented from becoming misaligned upon transporting the can from a piston moving
station for the expulsion of excess air to a valve assembly crimping station.
[0022] These and other objects will become apparent from the following description and claims
in conjunction with the drawings.
[0023] The present invention may be generally summarized as a method of filling and pressurizing
a can having a top end with an opening, a side wall, a bottom wall formed with a hole,
wherein said side wall and said bottom wall provide an enclosed volume, and a piston
positioned within said can enclosed volume, said piston having a periphery closely
adjacent said side wall, with said piston being slidable along the axis of the can,
said method comprising the steps of:
(a) positioning a nozzle having a discharge end with a discharge orifice so that said
discharge orifice is located near said top opening of said can;
(b) dispensing a viscous product flowing under pressure in said nozzle into said can
enclosed volume through said nozzle with a pressure sufficient for causing said viscous
material impinging on said piston to spread toward the periphery of said piston and
said side wall;
(c) continuing dispensing said viscous product into said can enclosed volume through
said nozzle in order to fill said can with a selected amount of said viscous product;
(d) maintaining the position of said nozzle near said top opening of said can throughout
said dispensing steps (b) and (c);
(e) maintaining said can stationary with respect to motion parallel to said can axis
throughout said dispensing steps (b) and (c);
(f) placing valve assemly means into the top opening of said can after said dispensing
steps (b) and (c);
(g) moving said piston upwardly in said can so that said viscous product substantially
fills the enclosed volume of said can above said piston while permitting gas to flow
out of the top opening of said can during said upward movement of said piston;
(h) applying fluid pressure to the hole at the bottom of said can thereby providing
a pressure beneath said piston;
(i) plugging said hole in the bottom of said can;
(j) restraining said valve assembly means in the top opening of said can and restraining
said can during said piston moving step (g) said fluid pressure applying step (h)
and said plugging step (i); and
(k) maintaining a pressure within said can below said piston at the exterior ambient
pressure or greater throughout said steps (a) through (j)..
[0024] In step (j), the valve assembly means may be restrained, for example, by mechanical
means external to the aerosol can or by the means connecting the valve assembly to
the body of the can. Step (k) points out that, in accordance with the method of the
present invention, a vacuum is not applied to the hole in the bottom wall of the can
in order to draw viscous product into voids between the surface of the piston and
viscous product.
[0025] One important aspect of the present invention is that the viscous product is discharged
from the nozzle at high velocity sufficient to cause spreading of a viscous product
impinging on the piston at the start of filling toward the side wall of the can.
[0026] The nozzle for dispensing the viscous product may have a cross-sectional geometry
so that fluid communication between the enclosed volume of the can and the exterior
of the can is restricted during the dispensing of a viscous product into the can from
the nozzle. This results in building a positive pressure within the enclosed volume
of the can during the dispensing of the viscous product which assists in filling any
voids between the viscous product and the piston.
[0027] A gaseous pressure may be applied to the top opening of the can after the viscous
product is dispensed into the can in order to substantially fill any voids between
the viscous product and the piston.
[0028] A preferred nozzle for discharging the viscous product into a can will gradually
constrict the viscous product flowing in the nozzle. This substnatially prevents expansion
of the viscous product upon exiting the discharge orifice of the nozzle and substantially
prevents a jet of viscous product after being discharged from the nozzle from expanding.
[0029] A pair of parallel, spaced apart tracks may be positioned over the piston moving
station to restrain the valve assembly seated on an edge member surrounding the top
wall opening of the can during movement of the piston. The spaced apart tracks would
extend a distance toward a valve assembly fastening or crimping station sufficient
to prevent the venting of pressure from the interior of the can from misaligning the
valve assembly with respect to the top wall opening when the can is being transported
from the piston moving station to the valve assembly fastening station.
[0030] The following is a description of some specific embodiments of the invention, reference
being made to the accompanying drawings, in which:
In the drawing, forming part hereof:
Fig. 1 is a schematic vertical cross-sectional view of an aerosol can having a slidable
piston positioned at a filling station wherein a nozzle dispenses a viscous product
into the can in accordance with the present invention;
Fig. 1A is a portion of a horizontal cross-sectional view taken along line lA - lA
of Fig. 1;
rig. e is a schematic elevation view, partly in cross-section, similar to the view
of Fig. 1 illustrating the dispensing of a viscous product into an aerosol can having
a slidable piston at a time just after the start of dispensing of the viscous product
and wherein the discharge nozzle has a preferred smooth, gradual converging cross-section
near the discharge end of the nozzle;
Fig. 3 is a schematic elevation view, partly in cross-section, of a discharge nozzle
having a preferred smooth, gradual converging cross-section near the discharge end
of the nozzle for use in discharging a viscous product into an aerosol can such as
illustrated in Figs. 1 and 2;
Fig. 4 is a schematic fragmentary elevation view of an alternate location of a discharge
nozzle near the top end opening of a piston-type aerosol can in accordance with an
alternate embodiment of the present invention;
Fig. 5 is a schematic vertical cross-sectional view illustrating the pressurization
through the top opening of a piston-type aerosol can of viscous product disposed in
the piston-type aerosol can in order to force the viscous product into contact with
the upper surface of the piston and around the skirt of the piston in accordance with
the present invention;
Fig. 6 is a schematic vertical cross-sectional view of a piston-type aerosol can filled
with a viscous product and having disposed in the top opening thereof a valve assembly
means;
Fig. 7 is a schematic elevation view, partly in cross-section, illustrating the upward
movement of a piston by means of a pressurized fluid in a piston-type aerosol can
after the can has been filled with a selected amount of a viscous product and also
illustrates track members, in accordance with the present invention, for restraining
a valve assembly member positioned in a top wall opening of such a can during the
upward movement of the piston;
Fig. 8 is a schematic elevation view, partly in cross-section, illustrating a prior
art clamping head restraining a piston-type aerosol can and a valve assembly means
positioned in the top wall opening of such a can during a piston moving step such
as illustrated in Fig. 7;
Fig. 9 is a schematic side elevation view illustrating track members, in accordance
with the present invention, extending fram a piston moving station as illustrated
in Fig. 7 to a valve assembly means crimping or fastening station as illustrated in
Fig. 11;
Fig. 10 is a schematic elevation view taken along line 10-10 of Fig. 9 illustrating
track members in accordance with the present invention;
Fig. 11 is a schematic elevation view, partly in cross-section, illustrating a crimping
station for crimping a valve assembly to the top wall of a piston-type aerosol can;
and
Fig. 12 is a schematic elevation view, partly in cross-section, illustrating a station
for pressurizing the region of a piston-type aerosol can below the piston and inserting
a grommet in a hole located in the bottom wall of the aerosol can.
[0031] In the figures of the drawing, like part numbers indicate like parts.
[0032] In order to afford a more complete understanding of the present invention and an
appreciation of its advantages, a description of the preferred embodiments is presented
below.
[0033] Fig. 1 illustrates a conventional cylindrically shaped aerosol can or container 10
comprising substantially cylindrical side wall 11 to the bottom edge of which a bottom
wall 12 is secured in a fluid-tight manner. Bottom wall 12 is of a downward concave
shape so that it will not be bellied out by pressure within the can. The bottom wall
12 is furnished with a hole 13, the purpose of which will hereinafter be described.
A top wall 14 is secured in a fluid-tight manner to the upper edge of sidewall 11.
The top wall 14 has an opening 15 surrounded by an edge member 16. The type of can
described is often referred to in the art as a "three-piece can." Such cans are typically
fabricated from sheet metal.
[0034] It will be understood that the invention may also be practiced with what is frequently
referred to in the art as a "two-piece" can or container in which the side wall and
either the top wall or bottom wall are formed as one piece by a deep drawing operation.
The invention may also be practiced using what is referred to in the art as a "dimple
cup" valve assembly.
[0035] In a three-piece can, such as illustrated in Fig. 1, the side wall 11 is formed from
initially flat stock which is curved into the cylindrical shape. With reference to
Fig. lA, the two meeting edges 18, 19 are welded together to form a seam 20 extending
longitudinally along the can.
[0036] Positioned within can 10 is a conventional shell-like piston 21 fabricated, e.g.,
from a suitable molded plastic such as polyethylene. The piston has a cylindrical
side wall 22 merging into a generally frusto-conical shaped top wall 23. The piston
is slidable axially (upwardly in Fig. 1) with respect to the can. The piston top wall
is formed with a depression 24 adapted to accommodate the portion 26 of a valve assembly
25 (Fig. 6) which projects into the interior of the can. The top wall of the piston
21 is generally shaped to conform to the inner surface of the top wall 14 of the can
and the lower portion 26 of valve assembly 25 so that when the piston reaches the
top of the can it will have expelled substantially all the product remaining in the
can. The interior of the shell-like piston defines a space 27 for accommodating a
pressurized fluid.
[0037] With reference to Fig. 1A, seam 20 projects into the can making the internal cross-section
of the can side wall 11 non-circular in the region of seam 20. When the space 27 within
the piston 21 is pressurized [as will hereinafter be discussed] the piston side wall
22 is pressed against the inner surface of can side wall 11 to produce a snug but
slidable fit. However, the piston side wall does not have sufficient flexibility to
conform to the internal ridge formed by the seam 20. Consequently, spaces 28 result
between the piston sidewall 22 and the can sidewall 11 on both sides of the seam 20.
[0038] Can 10 is filled with a viscous product 29 by a nozzle 30 which is positioned such
that the discharge end 31 forming a discharge orifice is located near the top opening
15 of the can 10. The nozzle 30 would be connected by suitable conduit means 32 [Fig.
2] to a reservoir for holding a viscous product to be discharged into the can [the
last elements being conventional and not illustrated]. Suitable pumping or pressurizing
means [not illustrated] are provided for discharging a high velocity viscous product
jet from the nozzle 30 with a pressure sufficient for causing the viscous product
impinging on the piston to spread toward the periphery of the piston and the side
walls 11 of the can. [Best illustrated in Fig. 2.] When the pressure of the viscous
fluid being discharged from the nozzle is sufficient to cause some small amount of
cavitation when the jet of viscous product 35 discharged from the nozzle 30 strikes
the top surface of the piston 21 at the start of filling the can, this assists the
spreading of the viscous product 29 toward the periphery of the piston 21 and the
side wall 11 of the can and into the space 36 between generally frusta-conical piston
wall section 23 [i.e., the piston skirt] and side wall 11 of the can. Suitable means
[not illustrated], such as air cylinders, would be provided for positioning nozzle
30 with respect to top opening 15 of the can.
[0039] For many viscous products, selecting an appropriate nozzle discharge pressure for
the viscous product will cause sufficient spreading of the viscous product to substantially
avoid the formation of voids between the viscous product discharged into the can and
the top of the piston including the space 36.
[0040] It should be noted that the nozzle 30 is located near the top end of the can 10 during
the entire operation of dispensing the viscous product from the nozzle into the can
for filling of the can with a selected amount of viscous product. This increases the
speed of filling the can in comparison with prior art methods of filling the can wherein
a tubular dispensing member is positioned near the piston at the bottom of the can
and either the can was lowered or the tubular dispensing member was withdrawn from
the can as the can was filled with a viscous product. In addition, in accordance with
the method of the present invention, since the viscous product dispensing nozzle 30
remains stationary near the top end of the can 10 during the filling of the can, the
expensive prior art equipment used to move the can and the tubular dispensing member
relative to one another responsive to the rate at which the can is filled is no longer
required.
[0041] 4 preferred nozzle shape for use in the present invention is illustrated in Figs.
2 and 3. The preferred nozzle shape, as illustrated in Figs. 2 and 3, is a nozzle
having a smooth, gradually converging cross-section parallel to the axis
3f the nozzle [vertical cross-section as illustrated in Fig. 2 and 3]. The smooth,
gradually converging nozzle cross-section is suitably located near the discharge end
31 of the nozzle 30. The purpose of such a nozzle is to provide substantially laminar
flow [i.e., substantially non- turbulant flow] of the pressurized viscous product
as it approaches the discharge end of the nozzle. To obtain such a flow of the pressurized
viscous product, it is desirable to avoid abrupt changes in the cross-section of the
nozzle conduit in which the viscous product is flowing. A nozzle having the shape
as illustrated in Figs. 2 and 3 also substantially prevents expansion of the jet of
the viscous product 35 which is being discharged from the discharge orifice of the
nozzle 30. Significant expansion of the jet of viscous product discharged from the
nozzle 30 would result in energy losses and degrade the spreading of the viscous product
which strikes the upper surface of the piston toward the side walls of the can during
the initial filling of the can.
[0042] Referring to Fig. 3, discharge nozzle 30 comprises a conduit 39 for transporting
a viscous product under pressure. Conduit 39 has a circular cross-sectional area A
1. Near the discharge end 31 of nozzle 30, the circular cross-sectional area of the
nozzle fluid conduit 39 is gradually and smoothly contracted 38 to a smaller cross-sectional
area A
2. The diameter of the viscous product jet 35 discharged from the discharge orifice
of nozzle 30 is D
1. Diameter D
1 is substantially equal to the diameter of the nozzle fluid conduit when it has the
cross-sectional area A
2. That is, there is substantially no expansion of the viscous product upon discharge
of the viscous product from the nozzle 30. The diameter of the viscous product jet
35 at a distance spaced from the discharge end 31 of nozzle 30 is D
2, where D
2 substantially equals D
1. That is, there is substantially no expansion of the viscous product jet 35 after
it has been discharged from the nozzle 30. Thus there are only minimum energy loses
in the viscous product jet due to expansion and turbulence in the jet.
[0043] As hereinbefore discussed, avoiding expansion and turbulence in the viscous product
jet has been found to be important in order to obtain the spreading of the viscous
product upon striking the piston wherein striking of the piston by the jet is desirably
accompanied by a small amount of cavitation.
[0044] With reference to Fig. 3, examples of suitable dimensions for the nozzle are: A
1 = 1.76 square inches; A
2 = 0.196 square inches; D
1 = D2 = 0.5 inches; angle X = 30°. When the viscous product is latex caulk, a pressure
of, e.g., about 36 p.s.i.g. is suitable.
[0045] A gradually converging nozzle used to limit the expansion of a jet of discharged
fluid is generally known in the field of fluid mechanics. Prior to the present invention,
the advantages of using a gradually converging nozzle to fill a piston-type aerosol
container with a viscous product had not been known. Heretofore, converging nozzles
have not been used with equipment for filling piston-type aerosol containers with
a viscous product.
[0046] As illustrated in Figs. 1 and 2, the discharge end 31 of the nozzle 30, positioned
near the top end of can 10, is disposed within the can 10. In many instances it is
desirable that the cross-sectional area of the nozzle 30 adjacent the top end of the
can 10 be less than but substantially equal to the cross-sectional area of the top
end opening 15 of the can. Thus, only a small annular area 40 will be provided for
permitting the escape of air from the interior of the can to the exterior as viscous
product 29 fills the can. The interior of the can 10 [i.e., the enclosed volume of
the can] may thus be said to be in restricted fluid communication with the exterior
of the can. Accordingly, there will be a positive pressure buildup in the can enclosed
volume as the can is filled with viscous product. The positive pressure buildup will
assist the viscous product filling any voids between the viscous product 29 and the
piston 21 and assist in having the viscous product enter space 36 between piston wall
23 and can side wall
11. In many applications, sufficient positive pressure can be built up to force the
viscous product between the side of the piston 23 and the side wall of the can 11.
[0047] Examples of suitable dimensions are as follows: If the diameter of the top opening
15 of the can is about 1 inch, the external diameter of the nozzle 30 adjacent the
top opening 15 of the can may be about 0.975 inches.
[0048] An alternative way to build a positive pressure in the can enclosed volume when the
viscous product is being dispensed into the can would be to have the discharge end
31 of the nozzle rest on the edge member 16 surroundings the opening 15 of the top
wall 14 of the can [not illustrated]. The discharge orifice of the nozzle 30 would
be aligned with the top opening 15 of the can. The resting of the discharge end 31
of nozzle 30 on edge member 16 would also result in restricting fluid communication
between the internal volume of the can 10 and the exterior of the can thereby causing
positive pressure to build in the can when viscous product is being dispensed into
the can.
[0049] Fig. 4 illustrates an alternate location for the nozzle 30 having a discharge end
31 positioned near the top opening of the can 10 in accordance with the present invention.
In this embodiment of the invention, the discharge orifice of the nozzle 30 discharge
end 31 is positioned near the top opening 15 of the can 10 but external to the enclosed
volume of the can. In this embodiment, it is desirable for the diameter of the nozzle
discharge orifice to be substantially less than the diameter of the top opening 15
of the can. Hence, the diameter of the jet of viscous product 35 discharged from the
nozzle 30 will be substantially less than the diameter of the top opening of the can.
The reason for this is that if the diameter of the jet of viscous product was close
to the diameter of the top opening of the can, rushing air escaping from the can as
the can is filled with viscous product will carry with it some of the viscous product
trying to enter the can. It will be appreciated that this would cause the spatter
of viscous product about the work area.
[0050] Dimensions suitable for the practice of the embodiment of the invention illustrated
in Fig. 4, could be, for example, the diameter of the nozzle discharge orifice and
hence the diameter of the jet of viscous product being about one-half the diameter
of the top end opening of the can. It will be appreciated that in embodiments of the
present invention as illustrated in Fig. 4, there will not be substantial positive
pressure buildup within the enclosed volume of can 10 during the filling of the can
with the viscous product.
[0051] The next step, in accordance with the present invention, which follows filling the
can with a selected amount of viscous material, is optional and would be practiced
when circumstances dictate. In some instances, after the filling of a can 10 with
a selected amount of viscous product 29, there may remain some spaces or voids between
the viscous product and the upper surface of the piston 21 especially in region 36.
[0052] In accordance with the present invention, as illustrated in Fig. 5, the viscous product
29 may be forced further down and around the skirt area 23 of the periphery of upper
surface area of the piston 21 in order to fill any voids that may exist in the space
36 between piston surface area 23 and side wall 11 of can 10 by introducing fluid
pressure, most suitably gaseous pressure in the form of air pressure, at the top opening
15 of can 10. The pressure should not be so great that it will force the viscous product
under the piston 21.
[0053] The top wall 14 of can 10 may be engaged by a cylindrical clamping member 42 forming
an enclosed hollow space 45. The bottom edge of clamping member 42 is provided with
a seal 43, fabricated from an elastomer or rubber like material, for engaging the
top wall 14 of can 10. A conduit 44 would be connected to a source of air pressure
[not illustrated] and penetrates the wall of clamping member 42 for introducing air
pressure on the top of viscous product 29 through top opening 15 of can 10 for further
forcing viscous product 29 into contact with the upper surface of the piston and especially
into space 36. The top wall of clamping member 42 may be connected by a rod 46 to
a suitable means, such as an air operated cylinder [not illustrated], for moving clamping
member 42 up and down as desired.
[0054] When the can 10 is filled with a viscous product, in accordance with the method of
the present invention such as illustrated and described in conjunction with Figs.
1 and 2, the optional pressurization step of the present invention illustrated in
Fig. 5 has been found useful when the viscous product is latex caulk or silicone caulk.
When the can 10 is filled with a viscous product, in accordance with the method of
the present invention such as illustrated and described in conjunction with Figs.
1 and 2, the optional pressurization step of the present invention illustrated in
Fig. 5 has been found generally not to be necessary when the viscous product is cream
or gel.
[0055] Typical pressures used may be, e.g., about 10 p.s.i.g. to 80 p.s.i.g. The typical
length of time of pressurization may be, e.g., about 1 second to 3 seconds. These
pressures and times are only given by way of example and it will be understood that
others may be used.
[0056] The determination of whether or not the optional pressurization step of the present
invention is necessary or desirable would depend on factors such as the viscosity
of the viscous product introduced into the can, the product flow characteristics,
the pressure, and the velocity at which the viscous product is introduced into the
can during the filling step, and the size of the can. One skilled in the art could
perform routine tests with selected viscous products and selected can sizes and selected
filling pressures to determine if the optional pressurization step in accordance with
the present invention is desired prior to filling of cans on a production line scale.
[0057] The pressurization step of the present invention described in conjunction with Fig.
5 represents an important advance in the art. Heretofore, in order to further force
the viscous material around the skirt region of the upper surface of the piston, the
prior art used a vacuum method wherein a vacuum was introduced at the hole 13 located
in the bottom wall 12 of can 10. Such a method is described in U.S. Patent No. 3,897,672.
Although the vacuum method satisfactorily forced the viscous material around the skirt
of the piston, this method was slow and is a very limiting factor in high speed operations.
The pressurization method, in accordance with the present invention, will force the
viscous product around the piston more rapidly than the prior art vacuum method. It
will be appreciated that the higher speed pressurization method of the present invention
is complementary to the higher speed automated filling method of the present invention
for use in high speed filling operations.
[0058] It will be appreciated, that if desired, the vacuum method disclosed in U.S. Patent
No. 3,897,672 may be used in combination with the viscous product filling method described
herein in conjunction with Figs. 1 to 4. It will also be appreciated that the pressurization
method of the present invention used to force viscous material around the skirt of
the piston, described in conjunction with Fig. 5, may be usefully employed with prior
art methods for dispensing a viscous product into an aerosol container or can.
[0059] Although not preferred, the pressurization method of the present invention described
in conjunction with Fig. 5 may also be practiced after the valve assembly has been
placed into the top opening of the aerosol can. In this instance, the valve assembly
would be opened by mechanical means and the pressure applied through the open valve.
[0060] The next step in the method of filling an aerosol can with a viscous product is to
insert a valve assembly means 25 into the hole 15 in the top wall 14 of the can 10
such as illustrated in Fig. 6. The valve assembly means 25 rests on the edge member
16 surrounding hole 15. The step of inserting the valve assembly means in the hole
15 and the mechanical means for doing so are conventional and are not illustrated.
[0061] The next step of the method of the present invention is illustrated in Fig. 7. Clamping
head 50 includes clamping legs 51 for engaging top wall 14 of can 10. Clamping head
50 is connected to rod 52 which is connected to suitable means [not illustrated] for
moving clamping head 50 up and down. Track members 60 [which will hereinafter be discussed
in detail] are disposed within clamping head 50 and are spaced just slightly above
lip 34 of valve assembly means 25. A nozzle 53 engages hole 13 in bottom wall 12 of
can 10. The nozzle 53 is provided with a seal 54 for making a substantially fluid-tight
engagement with the bottom 12 of can 10. Nozzle 53 is connected to a source of pressurized
air [not illustrated] by conduit 55. Nozzle 53 is mounted on a rod 56 which is connected
to suitable means for selectively moving nozzle 53 up and down, i.e., into and out
of engagement with the bottom wall 12 of can 10 in alignment with hole 13.
[0062] Pressurized air from nozzle 53 will force slidable piston 21 upwardly in can 10 which
in turn pushes viscous product 25 upwardly in the can until it substantially fills
the air space 57 above the viscous product. That is, the enclosed volume of the can
10 above piston 21 has been substantially filled with the viscous product 25. As hereinbefore
discussed, valve assembly means 25 has been placed but not fastened on edge member
16 surrounding hole 15 in the top wall 14 of can 10. As piston 21 moves upwardly in
can 21, valve assembly 25 will be lifted off edge member 16 by the air being displaced
from space 57 until the valve assembly contacts tracks 60. A path is thus provided
for air to flow out of hole 15 between edge member 16 and the lip 34 of valve assembly
means 25. The tracks 60 only permit minimal upward movement of valve assembly means
25 so that valve assembly means 25 is substantially retained within hole 15 and enough
space is not provided for the viscous product to leave the can. Tracks 60 may be said
to be restraining valve assembly means 25. It will be appreciated that clamping member
25 is holding or restraining can 10 in place during this piston moving step.
[0063] The step illustrated in Fig. 7 may be referred to as a piston moving step or piston
positioning step and may take place at what may be referred to as a piston moving
ata- tion. The use of the track members 60, which will hereinafter be discussed, forms
part of the present invention.
[0064] Instead of using tracks 60 of the present invention, the piston moving step may be
performed using a conventional clamping head 65 such as illustrated in Fig. 8 and
discussed in U.S. Patent No. 3,897,672. The clamping head 6
5 would be provided with a lower cylindrical portion for engaging the top wall 14 of
the can 10. Openings would be provided in the clamping head 65 for the escape of air
expelled from can 10 during the piston moving step. Clamp 65 would be provided with
an internal shoulder 66 which, when the clamp engages can top wall 14, is spaced just
slightly above lip 34 of valve means 25. The clamping head 65 would be connected,
e.g., by a rod member 67 to suitable means, such as air cylinders, for moving clamping
head 65 upwardly and downwardly.
[0065] Use of a conventional clamping head 65, such as illustrated in Fig. 8, would be satisfactory
with slow moving operations such as single station indexing machines. However, use
of tracks 60, in accordance with the present invention, is particularly useful in
high speed automated operation such as in-line, multiple index, multiple head machines
as will be appreciated from the detailed discussion which will follow.
[0066] The piston moving step discussed in conjunction with Fig. 7 disclose the use of a
pressurized fluid, typically a pressurized gas such as air, for moving piston 21 upwardly
in can 10. It will be appreciated that one skilled in the art may use other means
for moving piston 21. For example, piston 21 could be moved upwardly in can 10 by
mechanical means by inserting a rod having appropriate control mechanisms through
hole 13 and into contact with piston 21.
[0067] The viscous product dispensing step of the present invention, discussed in conjunction
with Figs. 1 to 4, offers advantages over the prior art viscous product dispensing
methods with respect to the piston moving step discussed in conjunctiol with Fig.
7.
[0068] When a can is filled with a viscous product by the hereinbefore described dispensing
method of the present invention, a slight depression 68 is left in the center region
of the viscous product as seen in Figs. 1 and 5.
[0069] In comparison, the prior art viscous product dispensing methods of moving a can downward
as the can fills or withdrawing a tubular dispensing member from a can as the can
fills with viscous product left a coning effect in the center region of the upper
portion of the viscous product dispensed into the can. This coning effect may be observed
in Fig. 1 of U.S. Patent No. 3,897,672.
[0070] This coning effect has the following disadvantages with respect to the piston moving
step discussed in conjunction with Fig. 7. When the piston 21 is moved upward in the
can 10 during the piston moving step, air will become trapped between the viscous
product and the top wall 14 especially in the regions toward the side wall 11. This
trapped air will result in undesired sputtering and/or foaming of the viscous product
when it is discharged from the can. It will be appreciated that the slight depression
left in the center region of the viscous product by the filling method in accordance
with the present invention will substantially eliminate trapped air between the viscous
product and the can top wall 14 after the piston moving step and this will substantially
eliminate such problems of sputtering and foaming of the viscous product which result
from such trapped air.
[0071] The track members 60 of the present invention will now be discussed in conjunction
with Figs. 7, 9, 10 and 11. After the piston 21 has been moved upwards in the can
10 to expel air in the space 57 above the viscous product, the can is next moved [as
indicated by the arrow 69 of Fig. 9] to a crimping or fastening station [Fig. 11]
where the valve assembly means 25 is crimped or fastened in a fluid tight manner to
the can 10.
[0072] As illustrated in Fig. 7 and as hereinbefore discussed, parallel, spaced apart tracks
60 are positioned a slight distance above and in alignment with lip 34 of valve assembly
means 25. Upward movement of piston 21 in the can 10 cause gas in space 57 to move
the valve assembly means 25 a small distance upward into abutment with tracks 60.
The upward movement of the valve assembly means 25 is thus limited by tracks 60 to
retain the valve assembly means within the can top wall opening 15. There is sufficient
upward movement of the valve assembly means 25 to provide a path to permit flow of
gas out of can 10 via the top wall opening 15 between can edge member 16 and the lip
34 of the valve assembly means 25.
[0073] After the piston 21 has been moved upward in the can, the clamping head 50 is removed
from the can, typically by upward movement of the clamping head 50. The parallel,
spaced apart tracks are stationary and thus retain their position with respect to
the valve assembly means 25. After removal of the clamping head 50, the can is transported
to the crimping station 70 [Fig. 11] by conventional mechanical means [not illustrated].
[0074] As best illustrated Fig. 9, the stationary, parallel, spaced apart tracks 60 extend
from the piston moving station toward the crimping station while retaining their relationship
with valve assembly means 25 of being in alignment with and spaced a small distance
above the lip 34 of the valve assembly means.
[0075] The reason the tracks 60 extend toward the crimping or fastening station is as follws.
After the piston moving step has been completed and the clamping head 50 has been
removed, residual pressure may remain and thus the escaping gas which results from
the residual pressure [or the viscous product itself] could displace the valve assembly
means 25 with respect to the can top wall opening 15 when the can is being transported
to the crimping station. Misalignment of the valve assembly could cause an unsatisfactory
crimping of the valve assembly to the edge member 16 and thus result in the need to
reject the filled can. In addition, the misaligned valve assembly could result in
a jam at the crimping station and necessitate stopping the production operation while
the crimping station is unclogged.
[0076] Prior art clamping heads 65 such as illustrated in Fig. 8 and which did not have
the tracks 60, in accordance with the present invention, resulted in these problems
of misaligned valve assemblies which have been solved by the tracks 60 of the present
invention. One skilled in the art will readily appreciate that the tracks 60 of the
present invention would be especially useful when high speed automated operations
are desired.
[0077] The tracks 60 of the present invention may extend all the way to being adjacent to
the crimping or fastening station, if this is desired. The tracks 60 should at least
extend a distance from the piston moving station toward the crimping or fastening
station which is sufficient to permit venting of pressure from the enclosed volume
of the can 10 above the piston during transporting of the can from the piston moving
station to the crimping station in order to prevent misalignment of the valve assembly
means.
[0078] Fig. 9 discloses the tracks 60 extending toward the valve assembly crimping or fastening
station which is illustrated in Fig 11. End 61 of track 60 may be adjacent the fastening
or crimping station. The can 10 is illustrated in Fig. 9 as being located in the piston
moving station which is illustrated in detail in Fig. 7. The can 10 would be transported
from the piston moving station to the crimping station in the direction of the arrow
69. Means 62 are illustrated for mounting the tracks 60 in their desired stationary
position. Means for mounting tracks 60 are not illustrated in detail because the could
readily be provided for by one skilled in the art. It will be appreciated that mounting
means 62 could be adjustable in order that tracks 60 can be located in selected stationary
positions for cans of various sizes.
[0079] Fig. 10 is a schematic elevation view along line 10-10 of Fig. 9 illustrating parallel,
spaced apart track members 60A and 60B of tracks 60 and their mounting means 62.
[0080] It will be appreciated by one skilled in the art that the track members 60, in accordance
with the present invention, may be usefully employed with other methods for filling
a piston type aerosol can with a viscous product such as the method as disclosed in
U.S. Patent No. 3,897,672.
[0081] One skilled in the art could practice the viscous product dispensing step of the
present invention and the top opening pressurization step of the present invention
using dimple cup valves. Such valve types, which are mounted in what is the top wall
of the aerosol can, are commonly used in the aerosol industry for charging or pressurizing
cans using the under the cap (i.e. under the valve) method. The dimples prevent the
valve from sealing on the lip during the charging. although not preferred, such a
valve type could be used with the viscous product filling method of the invention.
The dimple cup valve would be snapped into position prior to the can being placed
in the piston moving station. The dimple cup valve would eliminate the need for restraining
the valve in position when the piston was moved or positioned. However, the can itself
would have to be held or restrained in position by a clamping head while the piston
was being positioned.
[0082] After the piston has been moved upward in the can, the can is transported to a crimping
or fastening station [Fig. 11] where the lip 34 of the valve assembly means 25 is
crimped or fastened in a fluid tight manner to the edge member 16 of can 10. The crimping
station may comprise a crimping mechanism 70 having expanding collets 71 for performing
the crimping. The crimping station is not illustrated or discussed in detail because
it is convention in the piston-type aerosol can art.
[0083] The aerosol can 10 is next transported by conventional means to a piston pressurization
station illustrated in Fig. 12. A nozzle member 75 is provided to engage hole 13 in
the bottom wall 12 of the can. The nozzle would be connected to a source of pressurized
fluid, e.g., a pressurized gas such as pressurized air and would pressurize the region
of the can below shell-like piston 21. The nozzle would then plug the hole with a
precut grommet 76. A clamp member 77 would be provided to hold or restrain the can
10 in position when the can region below piston 21 is pressurized and the grommet
76 is inserted. Means [not illustrated] are provided for moving nozzle 75 and clamp
77 upwardly and downwardly with respect to the can 10. As illustrated in Fig. 12,
grommet 76 has been inserted into hole 13 so the nozzle 75 is in a downward position
out of engagement with the can bottom wall 12 and clamp 77 is in upward position out
of engagement with the top wall 14 of can 10. If the can were being pressurized, the
nozzle 75 would be in engagement with can bottom wall 12 in alignment with hole 13
and the clamp 77 would be in engagement with the top of can 10 to restrain the can.
The mechanisms of Fig. 12 have not been illustrated or described in detail because
they are conventional and well known in the art.
EXAMPLES
[0084] In order to provide a more complete understanding of the present invention, the following
examples, in accordance with the present invention, are set forth. It is understood
that these examples are only illustrative and are not intended to limit the scope
of the present invention which is defined in the claims.
Example I [overhead pressurization step not used]
[0085] A piston-type aerosol can having a nominal diameter of 2 2/16 inches and a nominal
length of 5 9/16 inches was filled with a gel type of product. The filling operation
took place at room temperature.
[0086] The diameter of the top wall opening of the can was about 1 inch. A gradually converging
discharge nozzle was positioned as illustrated in Figs. 1 and 2, near the top wall
opening of the can. The outside diameter of the nozzle at the discharge orifice was
about 0.975 inches. The inside diameter of the discharge orifice was about 0.5 inches.
About 150 grams of the gel viscous product were discharged into the can.
[0087] There were substantially no voids observed between the viscous product and the upper
surface of the piston including the region between the skirt of the piston and the
side wall of the can. The top wall opening pressurization step described in conjunction
with Fig. 5 was not required.
[0088] The slight depression in the center region of the upper surface of the viscous product
was observed. When the can was completely assembled and the region below the piston
pressurized, operation of the valve to discharge the viscous product did not result
in foaming or sputtering of the viscous product
Example II [overhead pressurization step used]
[0089] A piston-type aerosol can having a nominal diameter of 2 2/16 inches and a nominal
length of 7 1/2 inches was filled with latex caulk which is a viscous product having
a viscosity of about 220,000 centipose at 25°C. The filling operation tooke place
at room temperature.
[0090] The diameter of the top wall opening of the can was about 1 inch. A gradually converging
discharge nozzle was positioned as illustrated in Fig. 4 near the top wall opening
of the can. The outside diameter of the nozzle at the discharge orifice was about
0.975 inches. The inside diameter of the discharge orifice was about 0.5 inch.
[0091] The viscous product was discharged into the can at a pressure of about 36 p.s.i.g.
About 350 grams of the latex caulk were discharged into the can.
[0092] Some slight voids were observed between the viscous product and the upper surface
of the piston especially in the region between the skirt of the piston and the wall
of the can. The top wall opening pressurization step as described in conjunction with
Fig. 5 was practiced. The viscous product was subjected to air pressure of about 17
p.s.i.g. through the top wall opening of the can for about 2.3 seconds. After this
top wall opening pressurization step, there were substantially no voids observed between
the viscous product and the upper surface of the piston including the region between
the skirt of the piston and the wall of the can.
[0093] The slight depression in the center region of the upper surface of the viscous product
was observed. When the can was completely assembled and the region below the piston
pressurized, operation of the valve to discharge the viscous product did not result
in foaming or sputtering of the viscous product.
[0094] depending on the viscosity of the product, one skilled in the art may vary the pressure
at which the product is discharged into the can and vary the area or diameter of the
discharge or exit orifice of the dispensing nozzle to obtain optimal results for a
given product. Variation of these parameters will directly effect the velocity at
which the viscous product is discharged into the can. In general, the pressurization
step of the present invention, described in conjunction with Fig. 5, may be found
most useful when filling the aerosol can with a very viscous product.
[0095] Whereas the gradually converging nozzle [sometimes referred to in fluid mechanics
as a fire hose type nozzle] discussed in conjunction with Figs. 2 and 3 is preferred
in the practice of the present invention, other nozzle types which will discharge
the viscous product at high pressure and which will not cause the discharged high
velocity jet of viscous product to substantially expand upon exiting the nozzle discharge
orifice may prove satisfactory. The discharge of a high velocity jet of viscous product
is most important and in some instances an abruptly converging nozzle may be satisfactory
provided spreading of the viscous product occurs upon commencement of the filling
of a can.
[0096] Although preferred embodiments of the present invention have been described in detail,
it is contemplated that modifications may be made by one skilled in the art within
the spirit and scope of the present invention.
1. A method of filling and pressurizing a can having a top end with an opening, a
side wall, a bottom wall formed with a hole, wherein said side wall and said bottom
wall provide an enclosed volume, and a piston positioned within said can enclosed
volume, said piston having a periphery closely adjacent said side wall, with said
piston being slidable along the axis of the can, said method comprising the steps
of:
(a) positioning a nozzle having a discharge end with a discharge orifice so that said
discharge orifice is located near said top opening of said can;
(b) dispensing a viscous product flowing under pressure in said nozzle into said can
enclosed volume through said nozzle with a pressure sufficient for causing said viscous
material impinging on said piston to spread toward the periphery of said piston and
said side wall;
(c) continuing dispensing said viscous product into said can enclosed volume through
said nozzle into order to fill said can with a selected amount of said viscous product;
(d) maintaining the position of said nozzle near said top opening of said can throughout
said dispensing steps (b) and (c);
(e) maintaining said can stationary with respect to motion parallel to said can axis
throughout said dispensing steps (b) and (c);
(f) placing valve assembly means into the top opening of said can after said dispensing
steps (b) and (c);
(g) moving said piston upwardly in said can so that said viscous product substantially
fills the enclosed volume of said can above said piston while permitting gas to flow
out of the top opening of said can during said upward movement of said piston;
(h) applying fluid pressure to the hole at the bottom of said can thereby providing
a pressure beneath said piston;
(i) plugging said hole in the bottom of said can;
(j) restraining said valve assembly means in the top opening of said can and restraining
sail can daring said piston moving step (g) said fluid pressure applying step (h)
and said plugging step (i); and
(k) maintaining a pressure within said can below said piston at the exterior ambient
pressure or greater throughout said steps (a) through (J).
2. A method as recited in claim 1 wherein said nozzle discharge orifice located near
said top opening of said can is disposed within said can and wherein the cross-sectional
area of said nozzle adjacent said top opening of said can is less than but substantially
equal to said cross-sectional area of said top opening whereby fluid communication
between said can enclosed volume and the exterior is restricted thereby providing
a positive pressure within said can enclosed volume during said dispensing steps (b)
and (c) for filling any voids between said viscous product and said piston.
3. A method as recited in claim 1 wherein the discharge end of said nozzle contacts
said top end of said can with said discharge orifice aligned with said top opening
whereby fluid communication between said can enclosed volume and the exterior is restricted
thereby providing a positive pressure within said can enclosed volume during said
dispensing steps (b) and (c) for filling any voids between said viscous product and
said piston.
4. A method as recited in claim 1 wherein the nozzle discharge orifice located near
said top opening of said can is positioned external to said can enclosed volume with
said discharge orifice aligned with said top opening and wherein the cross-sectional
area of said nozzle discharge orifice is substantially less than the cross-sectional
area of said top opening of said can.
5. A method as recited in claim 4 wherein the diameter of said nozzle discharge orifice
is about 1/2 the diameter of said top opening.
6. A method as recited in any of claims 1 to 3, which further includes the step of:
(1) applying fluid pressure to said top opening after said viscous product dispensing
step (c) thereby substantially filling any remaining voids between said viscous product
and said piston.
7. A method as recited in claim 4 or claim
5 which further includes the step of:
(1) applying fluid pressure to said top opening after said viscous product filling
step (c) to substantially fill any remaining voids between said viscous product and
said piston.
8. A method as recited in claim 6 or 7 wherein said applying fluid pressure step (1)
is carried out prior to said valve assembly placing step (f).
9. A method as recited in claim 6 or 7 wherein said applying fluid pressure step (1)
is carried out after said valve assembly placing step (f).
10. A method as recited in any of the preceding claims which further includes:
constricting said viscous product flowing under pressure in said nozzle as said flowing
product approaches said discharge orifice of said nozzle thereby substantially preventing
expansion of said pressurized viscous product as it exits said discharge orifice and
substantially preventing expansion of a jet of viscous product discharged from said
nozzled during said dispensing steps (b) and (c).
11. A method as recited in claim 10 wherein said viscous product is gradually constructed.
12. A method as recited in any of the preceding claim wherein:
said nozzle has a fluid conduit for transporting said viscous product flowing under
pressure within said conduit terminating in said discharge orifice;
said conduit has a circular cross-sectional area A at a location remote from said
nozzle discharge end;
said discharge orifice has a circular cross-sectional area A2 with A2 being less than A1.
13. A method as recited in claim 12 wherein the cross-sectional area of said conduit
A is gradually and smoothly contracted to said cross-sectional area A
2 near the discharge end of said nozzle;
whereby expansion of said pressurized viscous product as it exits said discharge orifice
and expansion of a jet of viscous product discharged from said nozzle during said
dispensing steps (b) and (c) is substantially prevented.
14. A method as recited in any of the preceding claims wherein said can has a top
wall with an opening mounted on the top end of said can and further includes the steps
of:
positioning said valve assemply means in said top wall opening;
performing said piston moving step (g) at a piston moving station;
fastening said valve assembly means to said top wall of said can in an airtight manner
at a fastening station which is spaced from said piston moving station wherein said
valve assembly means fastening step occurs prior to said fluid pressure applying step
(h);
performing said valve assembly restraining step (j) during said piston moving step
(g) by:
providing a pair of parallel, spaced apart tracks positioned above said piston moving
station at a height and location such that said tracks are in alignment with and displaced
a small distance above said valve assembly means when said can is in said piston moving
station; whereby
said moving said piston upward causes gas within said can to move said valve assembly
means upward into abutment with said tracks with said upward movement of said valve
assembly being limited by said tracks to retain said valve assembly means within said
top wall opening of said can but permitting valve assembly means upward movement sufficient
to permit said flow of gas out of said top wall opening; and
transporting said can to said fastening station after completion of said piston moving
step wherein said parallel, spaced apart tracks extend a distance from said piston
moving station toward said fastening station sufficient to permit venting of pressure
from the enclosed volume of said o4n above Paid piaton during said transporting.
15. A method as recited in any of the preceding claims wherein said piston is moved
upwardly in said can in step (g) by applying a pressure through the hole at the bottom
of said can.
16. A method as recited in any of the preceding claims wherein said restraining of
said valve assembly means step (j) occuring during said piston moving step (g) permits
limited upward movement of said valve assembly to permit said gas to flow out of the
top wall opening of said can.
17. A method as recited in claim 16 wherein said can has a top wall with an opening
mounted on the top end of said can; and,
said valve assembly means placing step (f) comprises seating said valve assembly means
on an edge member surrounding said top wall opening but said valve assembly means
is not fastened to said edge during said valve assembly means placing step (f) whereby
said gas can flow out of the top wall opening of said can between said edge and said
valve assembly means during said piston moving step (g); and including the step of,
crimping said valve assembly means to said edge member surrounding said top wall opening
in an fluid tight manner following said piston moving step (g) and prior to said fluid
pressure applying step (h).
18. A method of filling and pressurizing a can having a top wall with an opening,
a side wall, a bottom wall formed with a hole, wherein said top wall, said side wall
and said bottom wall provide an enclosed volume, and a piston positioned within said
can enclosed volume, said piston having a periphery closely adjacent said side wall
with said piston being slidable along the axis of said can, said method comprising
the steps of:
(a) dispensing a viscous product into said can enclosed volume in order to fill said
can with a selected amount of said viscous product;
(b) placing a valve assembly into the top wall opening of said can after said dispensing
step (a) by seating but not fastening said valve assembly on an edge member surrounding
said top wall opening;
(c) moving said piston upwardly in said can at a piston moving station so that said
viscous product substantially fills the enclosed volume of said can above said piston
while gas flows out of the top wall opening of said can between said edge member and
said valve assembly during said upward movement of said piston;
(d) transporting said can to a valve assembly fastening station which is spaced from
said piston moving station;
(e) providing a pair of parallel, spaced apart tracks positioned above said piston
moving station at a height and location such that said tracks are in alignment with
and displaced a small distance above said valve assembly when said can is in said
piston moving station; whereby,
(1) said moving said piston upward causes gas within said can to move said valve assembly
upward into abutment with said tracks with said upward movement of said valve assembly
being limited by said tracks to retain said valve assembly within said top wall opening
of said can but permitting valve assembly upward movement sufficient to permit said
flow of gas between said edge member and said valve assembly; and wherein
(2) said parallel, spaced apart tracks extend a distance from said piston moving station
toward said fastening station sufficient to permit venting of pressure from the enclosed
volume of said can above said piston during said transporting step (d);
(f) fastening said valve assembly to said edge member in an fluid tight manner at
said fastening station;
(g) applying fluid pressure to the hole at the bottom of said can thereby providing
a pressure beneath said piston; and
(h) plugging said hole at the bottom of said can.
19. A method as recited in claim 18 which further includes the steps of:
(i) applying fluid pressure to said top wall opening after said viscous product dispensing
step (a) thereby substantially filling any voids between said viscous product and
said piston; and
(j) maintaining a pressure within said can below said piston at the exterior ambient
pressure or greater throughout said steps (a) through (i).
20. A method of filling and pressurizing a can having a top end with an opening, a
side wall, a bottom wall formed with a hole, wherein said top wall, said side wall
and said bottom wall provide an enclosed volume, and a piston positioned within said
can enclosed volume, said piston having a periphery closely adjacent said side wall
with said piston being slidable along the axis of said can, said method comprising:
(a) dispensing a viscous product into said can enclosed volume in order to fill said
can with a selected amount of said viscous product;
(b) applying a fluid pressure to said top end opening after said viscous product dispensing
step (a) thereby substantially filling any void between said viscous product and said
piston;
(c) placing valve assembly means into the top end opening of said can;
(d) moving said piston upwardly in said can so that said viscous product substantially
fills the enclosed volume of said can above said piston while permitting gas to flow
out of the top end opening of said can during the upward movement of said piston;
(e) applying fluid pressure to the hole at the bottom of said can thereby providing
a pressure beneath said piston;
(f) plugging said hole in the bottom of said can; and,
(g) restraining said valve assembly in the top opening of said can and restraining
said can during said piston moving step (d), said fluid pressure applying step (e)
and said plugging step (f).
21. A method as recited in claim 20 wherein said fuid pressure applying step (b) occurs
prior to said valve assembly means placing step (c).
22. A method as recited in claim 20 wherein said fluid pressure applying step (b)
occurs after said valve assembly means placing step (c).
23. A method as recited in claim 19 wherein said fluid pressure applying step (1)
occurs prior to said valve assembly means placing step (f).
24. A method as recited in claim 19 wherein said fluid pressure applying step (1)
occurs after said valve assembly means placing step (f).
25. A pressurized filled can manufactured by the method of any of the preceding claims