[0001] The invention is directed to an apparatus for assembling thin-walled container halves.
[0002] Attempts at assembling thin-walled container halves by conventional methods have
failed in that even if one of the halves is necked in prior to attempts at assembly,
the flimsy nature of the side walls prevents their retaining a cylindrical shape and
thus great difficulty has been experienced in rounding the parts and then axially
pushing them together.
[0003] In French Patent No. 1,224,793, a container is formed of thick-walled cylinder halves,
one of which is necked out and the second necked in, the second half being telescoped
into the first and the halve are then welded together. This may be effective for thick-walled
containers which retain their shape after reforming, but thin-walled containers, particularly
if made from relatively soft metal such as aluminum, are very unstable in retaining
their shape and thus are difficult to assemble and in forming the edges, are hard
to control. This is especially significant for high-speed production of 400-1000 units
per minute.
[0004] In the prior art, the bonding of telescoped container halves usually involves a welding
or brazing of the metal parts. Adhesive bonding as heretofore has been tried but has
been found wanting.
[0005] Various problems occur in obtaining an adequate sealing using adhesive bonding. Attempts
have been made by merely coating the exterior edge portion of the inner container
portion or the interior edge portion of the outer container portion. The two halves
then are telescoped. However, during the insertion movements the edge of the uncoated
portion would scrape off the coating from the coated portion and the residue remaining
would not in each instance be sufficient to provide a bond of required integrity.
[0006] The object of this invention is to provide a novel apparatus for assembling the container
halves which overcome the foregoing problems.
[0007] Accordingly, the present invention provides an apparatus for assembling a pair of
thin-walled cup-shaped container sections adapted to be assembled end to end and each
section comprising a cylindrical body wall having an open end defined by an end portion
of the body wall which normally assumes an out of round shape; comprising a support;
means for mounting said sections in axially spaced aligned relation and the end portion
of each opposing the other; a die assembly mounted on the support in a position to
receive one of the container sections at one side thereof and the other container
section at the opposite side thereof; said die assembly comprising an opening there
through; outer guide means at opposite sides thereof for guiding the end portions
of respective container sections into said opening; said opening being defined at
one side of the die assembly by a cylindrical surface disposed inwardly as said guide
means as a continuation thereof and of a diameter to snugly engage the external side
of a container section insertable therein to shape and hold the same round; said guide
means on the other side of said guide assembly extending through said shoulder and
defining an inner edge thereof; said shoulder having a radial extent slightly greater
than the thickness of the body wall of the container inserted into said cylindrical
sur - face area, and means for advancing said container sections toward one another
and telescoping the end portion of one container end portion into the other.
[0008] In use of the apparatus of the invention, the first and second container halves are
advanced toward each other at opposite sides of the die and the second half is forced
through the necking surface and is slightly necked in while the first half is disposed
in receiving position. Thus, as the second half is being necked in, it also wedges
into the first half. These operations are concurrent. Before the halves are fitted
one into the other, the second or entr- ing half has a coating of adhesive applied
thereto along its entering edge, although it will be understood the adhesive may be
applied within the outer (first) container half at its juncture edge portion.
[0009] The outer container is held round (squared) in the die assembly. The entering portion
of the inner container is slightly necked in while relatively advancing the two halves
toward each other and while holding them under control so that the inner container
portion easily enters the open end of the outer portion. The inner portion is under
compression and after release from the die, springs outwardly and produces a hoop
tension in the outer portion.
[0010] The adhesive preferably is a vinyl plastisol material which solidifies on being heated
after the container sections are mated. The container sections are released when telescoped
and the inner section expands and compresses the trapped adhesive and thus maintains
intimate pressed contact between the parts so that they adequately bond with the adhesive
as it cures or sets. Suitable adhesive materials for bonding the two container sections
together can be any known materials having adhesive properties including vinyl plastisols,
thermosetting epoxy resins and thermoplastic resins such as polyethylene, polypropylene.
Other adhesive materials include vinyl plastisol formulations, carboxylated polyolefin
resins and especially carboxylrted polypropylene resins of the type disclosed in U.S.
Patent 3,616,047.
[0011] These and other features and advantages of the invention will become more apparent
from the specification and the drawings, wherein:
Fig. 1 is a side elevational view partly in axial section of apparatus of the invention;
Fig. 2 is a cross-sectional view taken substantially on line 2-2 of Figure 1;
Fig. 3 is an enlarged cross-sectional view taken substantially on line 3-3 of Figure
1;
Fig. 4 is an enlarged fragmentary view of a portion of the die member in cross-section
showing the can parts in position preparatory to entering the die; and
Fig. 5 is a fragmentary axial vertical section taken substantially on line 5-5 of
Figure 3 showing the can parts in assembled position.
[0012] The preferred apparatus of the invention is illustrated in Figures 1-5. With reference
to these Figures, the apparatus 31 comprises a support frame 32 which has a plurality
of vertically aligned bearings 33 and 34 mounted thereon in which an operating shaft
assembly 35 is journaled.
[0013] The shaft assembly is split into two counter- rotary sections 38 and 40.
[0014] Shaft section 38 is connected to one jaw or clamp holder 42 and the shaft section
40 is connected to jaw or clamp holder 44 of a die 45. The jaw sections each carry
a half section segment 46 of a die ring 47. Each section 46 has a tongue 48 fitted
into a groove 50, in the associated jaw or clamp holder 42 or 44. Tn ad dition, there
is provided an end stop 52 at each end of segment 46 abutting the end of the same,
the stop being attached by screws 54, 54 threaded into the associated end portion
of the jaw section 42 or 14. Jaws 42, 44 have arms 55, 56 respectively at one of their
ends keyed by keys 57, 58 to the respective shaft sections 38 and 40.
[0015] The shaft sections 38 and 40 are connected to pistons 64, 66 of air or hydraulic
motors 68, 70, the pistons operating in cylinders 72, 74.
[0016] Thus, the clamps and their associated die sections are opened and closed by reversely
turning the respective shaft sections in order to admit cup-shaped container halves
or cups 75, 76 which are made of metal, preferably aluminum of about 6-10 mils in
thickness.
[0017] Associated delivery and discharge mechanism is used to bring the cups to the assembly
apparatus 31 and to remove the assembled container but are of no concern as to the
present invention.
[0018] As best seen in Figure 1 and 2, the assembly apparatus is provided with vacuum holders
78, 79 which are mounted on the frame and each have an arcuately shaped pocket with
a vacuum slot 81 connected with an associated vacuum line 83.
[0019] The holders 78, 79 releasably hold the upper and lower halves 75, 76 of the container
with the open end portions 85, 86 (Fig. 4) thereof facing each other. The clamps are
then closed about these open end portions as seen in the right half of Fig. 4. If
desired, the clamps may first be closed and the halves advanced toward each other
and entered into the upper and lower ends of the die 47. It will be noted that the
upper and lower end portions 88, 90 of the dies are provided with truncated conical
guide surfaces 93., 92 which flare downwardly and upwardly respectively and at their
outer ends are of a diameter greater than that of the body portions 93, 94 of the
upper and lower cup sections. Thus, the edge portions 85, 86 of the body portions
93, 94 are easily guided into the center portion of the die.
[0020] The center portion of the die has an upper cylindrical die portion with a surface
97, which is equal to substantially the outside diameter of the upper cup. The upper
cup is advanced into the surface 93 which rounds the lower edge portion of the upper
cup by an upper pusher 100 which has a cap 101 at the lower end of rod 102 of a piston
which operates in an air cylinder 103 carried by the frame.
[0021] The upper cup slips along the holder 78 and is guided into the cylindrical die surface
97 until the lower edge 105 of the upper cup seats upon the shoulder 106 at the bottom
of the squaring surface 107. Simultaneously, with the upper cup being inserted into
the cylindrical section 107, the lower cup is pushed upwardly by an air or hydraulic
cylinder 107 which has a base pod 108 bearing against the bottom or base 109 of the
lower or male cup. The edge portion 86 of the lower cup has been previously coated
with an appropriate adhesive 109. The edge portion 86 of the lower cup is very slightly
necked-in but not deformed as it moves past the shoulder 106. The inner edge of the
shoulder 106 is of a diameter slightly less than the inner diameter of the upper cup,
and the shoulder 106 hasa radial dimension slightly larger than the thickness of the
metal of the body wall of the upper cup.
[0022] It has been found that the fit of the lower cup edge portion into the upper edge
portion merely springs the metal of the lower cup very slightly without permanent
deformation and that upon release from the die, the hoop compressive forces on the
edge portion 56 are slightly relieved and tensile hoop stresses develop in the edge
portion 85. Thus, a tight fit is insured between the two halves and the adhesive which
is preferably thermoplastic polyolefin resins such as carboxylated polypropylene or
polyethylene as well as thermosetting resins such as epoxy resins. These resins, when
heated, will distribute and bond in shear the opposing outer surface 112 of the inner
portion 86 to the inner surface 113 of the outer portion 85. It will be noted that
no inner support is required to telescope the two cups into each other and no wrinkling
occurs at the juncture so that a good, leak-proof bond is developed which resists
separation of the two halves in shear. It will be understood that any cold adhesive
or thermoplastic adhesives may be used to bond the two halves.
[0023] After the two cup halves are assembled, the die is opened and the upper and lower
pushers separated and a vacuum withdrawn from the holders and the assembled unit is
withdrawn or drops out and the following two halves are entered into the apparatus
at opposite sides of the die and assembled in a continuous process.
1. An apparatus for assembling a pair of thin-walled cup-shaped container sections
adapted to be assembled end to end and each section comprising a cylindrical body
wall having an open end defined by an end portion of the body wall which normally
assumes an out of round shape; characterized by a support; means for mounting said
sections in axially spaced aligned relation and the end portion of each opposing the
other; a die assembly mounted on the support in a position to receive one of the container
sections at one side thereof and the other container section at the opposite side
thereof; said die assembly comprising an opening there through; outer guide means
at opposite sides thereof for guiding the end portions of respective container sections
into said opening; said opening being defined at one side of the die assembly by a
cylindrical surface disposed inwardly as said guide means as: a continuation thereof
and of a diameter to snugly engage the external side of a container section insertable
therein to shape and hold the same round; said guide means on the other side of said
guide assembly extending through said shoulder and defining an inner edge thereof;
said shoulder having a radial extent slightly greater than the thickness of the body
wall of the container inserted into said cylindrical surface area, and means for advancing
said container sections toward one another and telescoping the end portion of one
container end portion into the other.
2. The apparatus according to claim 1, characterized by mounting means comprising
a pair of vacuum cups disposed at opposite sides of the die assembly releasably supporting
the respective container sections for movements toward each other.
3. The apparatus according to claim 1 or 2, characterized by means for moving said
container sections toward each other.
4. The apparatus according to claim 1, 2 or 3, characterized by said die assembly
comprising a pair of complemental segments, and means for closing said segments prepatory
to assembly of said container sections and separable to release the assembled containers.
5. The apparatus according to claim 4, characterized by said support comprising a
pair of counterrotating shafts, and said die assembly comprising a pair of radially
separable and closable segments connected to respective shafts, and means programmed
to close and open the die segments to respectively dispose the die in assembly position
and in release position.
6. The apparatus according to any of claims 1 to 5, characterized by said die assembly
comprising a die ring having a frusto-conical guide surface tapered toward the die
center and forming a through opening therein; a cylindrical squaring surface extending
from the inner end of one of said guide surfaces; and a stop shoulder at the end of
said cylindrical surface remote from said one guide surface, said shoulder having
a radial width substantially equal to or slightly larger than the thickness of the
metal wall of a cup adapted to be inserted thereinto; the other of said guide surfaces
extending through said shoulder and forming the inner marginal edge thereof.
7. The apparatus according to claim 6, characterized by said die ring being split
diametrically into two halves and a holder for each half having a tongue and groove
interlock therewith, and means on each holder for securing the related ring half thereto.