[0001] The object of this invention is an automatic machine for the production of front-sealing
gaskets obtained by simultaneous spiral winding on a centring ring of a backing tape
of high mechanical strength and a tape made of material of high insulating characteristics
superimposed on one another.
[0002] There are known in engineering numerous types of gaskets made in the form of rings
capable of providing static front sealing, for example for the connection of tubes
or within packing glands.
[0003] It is also known that for the industrial production of such types of gaskets it is
necessary to wind according to a spiral two superimposed tapes having physical and
mechanical properties differing markedly from one another; in particular there is
first wound a tape of high mechanical strength, for example made of steel, which provides
the backing for the second tape made of material of high insulating characteristics
but highly brittle, such as for example asbestos and/or graphite.
[0004] There are also known machines which carry out the formation of such gaskets by a
semi-manual operation which requires constant control and auxiliary action by an operator
entirely dedicated to the machine.
[0005] There is therefore posed the technical problem of providing a fully automatic machine
for the production of gaskets of the spiral type described above.
[0006] Such results are obtained with the present invention, which provides an automatic
machine for the production of gaskets obtained by spiral winding of tapes of different
physical and mechanical characteristics on a supporting and centring ring, comprising
means for feeding such supporting rings to a rotary mandrel, a unit exerting radial
pressure on such rings, a unit for welding one of such tapes to the ring, a unit for
feeding a tape of high mechanical characteristics, a unit for feeding a second tape
of sealing material and a unit for controlling and synchronizing the feed to the mandrel
of such backing and sealing tapes interposed between the respective feed units, there
being furthermore provided means for the relative movement of the sealing tape feed
unit with respect to the synchronizing unit in a direction transversal to the direction
of feed of the said tapes to the mandrel, as well as means for moving the synchronizing
unit in a direction normal to the other two directions for the alignment of the direction
of feed of the tapes at a tangent to the preset circumference of the gasket and means
for maintaining such alignment as the outside diameter of the gasket increases.
[0007] Further details may be obtained from the following description given with reference
to the attached drawings, which show:
- In figure 1 :
- a schematic perspective view of the automatic machine according to the invention;
- In figure 2 :
- a partial schematic cross-section of the machine in fig. 1 drawn according to a vertical
plane;
- In figure 3 :
- a schematic cross-section according to plotting planes III-III of fig. 2;
- In figure 4a :
- a schematic view of the profiled steel tape at the start of winding on the inner ring;
- In figure 4b :
- a cross-section according to plotting plane IV-IV of fig. 4a;
- In figure 4c :
- the cross-section of a finished gasket;
- In figure 5 :
- a partial schematic cross-section illustrating the device for vertical positioning
of the synchronizing unit.
[0008] As shown in figure 1, the machine according to the invention is essentially comprised
of a control and programming part 2 capable of controlling the rotation of a mandrel
3 the axis of rotation of which constitutes the fixed reference for all the moving
parts of machine 1, which are in turn controlled according to programmed working sequences.
[0009] Such moving and operating parts, which will be described in detail hereinafter, are
substantially comprised of a feeder 10 for inner rings 11 which are applied to mandrel
3 in order to support the gasket both during the formation of the latter and on completion
of the gasket; a unit 20 exerting radial pressure on such rings 11; a welding unit
30 set against such pressure unit 20; a unit 40 for feeding a steel tape 41; a unit
50 for feeding tapes 51 made of insulating material and a unit 70 for control and
relative positioning with respect to the mandrel, as well as for the synchronization
and cutting of backing tape 41 and insulating tape 51, interposed between respective
feed units 40 and 50.
[0010] Unit 10 for the feeding of inner rings 11 is substantially comprised of a reservoir
12, moving on horizontal plane 12a, and an articulated arm 13 capable of taking a
ring 11 from the reservoir and positioning it coaxially to mandrel 3, which is equipped
with grippers 3a moving radially under control, capable of making ring 11 integral
with mandrel 3 which may thereby cause to rotate ring 11 for the formation of the
gasket.
[0011] Above mandrel 3 acts a pressure unit 20 consisting of an idle roller 21 operated
in translation by a piston 22 which brings about its descent into contact with supporting
ring 11 thereby generating pressure on the said ring and therefore on the gasket during
its formation.
[0012] In a position facing pressure unit 20 is provided a welding unit 30 - which is self-evident
and therefore only shown schematically in the figures and not described in detail
- which may be controlled in translation until it placed in contact with the gasket
for the weld to be applied between inner ring 11 and the profiled steel at the start
of formation of the gasket, and on outer ring 5b of the gasket 5 for the stable locking
of the spiral on completion of formation of the gasket.
[0013] Unit 40 for the feeding of steel backing tape 41 substantially consists of a tensioning
and regulating device comprising an idle roller 42 for the return of tape 41, a swivel
arm 43 and an idle return roller 44.
[0014] Unit 50 for the feeding of insulating tape 51 is substantially comprised of a supporting
arm 52 carrying a flange 52a, transversally to which is located a pin 53 on which
may rotate a multiplicity of reels 51a of insulating tape 51 from which is unwound
the said tape in order to feed mandrel 3.
[0015] Unit 50 for the feeding of insulating tape 51 may be made to rotate around a pin
55 in order to obtain the overturning of arm 52 so as to provide access both to the
said feed unit and to underlying synchronizing unit 70. Once set to the working position,
arm 52 is centred by means of two pins 56a and 57a actuated by respective cylinders
56b, 57b, which pins cooperate with corresponding holes 56c and slots 57c for the
centring in a direction parallel to feed direction Y-Y of tape 51 and for the movement
in direction Z-Z transversal thereto of the arm with respect to the synchronizing
unit (fig. 1).
[0016] Locking in the working position is performed by means of a hook 58 rotating around
a pin 58a against the opposing action of a spring 58b.
[0017] Such centring is made necessary because arm 52 may be moved via a slide 57d in a
transverse sense Z-Z with respect to direction Y-Y of feed of tape 51 in order to
feed to gasket 5 the insulating tape of a particular reel from the number located
on transverse pin 53, thus making possible the preselection of tapes 51 of different
materials in relation to the characteristics required for the specific gasket being
produced.
[0018] As illustrated in fig. 3, provision is also made for a pulley 59 to control the continuity
of movement of insulating tape 51 during the formation of the gasket, on which acts
in a radial sense a counteracting roller 60 out of a number of rollers pivoted to
a fixed shaft supported by shoulders 52.
[0019] Such pulley 59, provided with its own front surface of slots 59a, is operated by
a lever 59b integral therewith, pivoted at 59c and actuated by counteracting roller
60 via spring 59d. A cylinder 59e provides via hook 59f for wheel 59 to be moved away
from roller 60 during the change of reel 51a of insulating tape 51.
[0020] A sensor 59g is provided to indicate the stoppage of movement of the pulley in the
event of breakage of insulating tape 51 or unavailability thereof due to depletion
of the reel. This is made possible by the fact that, during rotation, pulley 59 presents
to sensor 59g slots 59a alternating with sections of solid area, such alternation
bringing about the emission of an intermittent signal by the movement-indicating sensor,
while the continuous presence of a void or solid area would bring about a continuous
signal corresponding to lack of movement of the pulley.
[0021] Longitudinal spring 64, secured to a support block 63, is fork-shaped so that the
two separate legs act on pin 65a supporting a roller 65.
[0022] Such pin 65a, as will be more fully described hereinafter, is operated in translation
by a roller 71 controlling the feed of tape 51.
[0023] Roller 65 acts via spring 64 to oppose roller 71 in the phase of feeding of insulating
tape 51.
[0024] Synchronizing unit 70 interposed between the two feed units 40 and 50 comprises a
first roller 71 controlling the feed of tape 51, on which it acts directly when pushed
into the operating position by a connecting rod 71a pivoted to the centre of roller
73 and actuated by a cylinder 71b the rod of which brings about, in the retracted
position, the movement of roller 71 away from tape 51 and, in the extended position,
the movement of roller 71 toward tape 51.
[0025] Roller 71 is made to rotate by indented wheel 72 driven by a belt 72a attached to
the hub of roller 73, which constitutes the male drawing roller of tape 41 and cooperates
with a second roller 74 constituting the female drawing roller. In this way, tape
41 may assume the arrangement shown in figures 4a, 4b, 4c, suitably designed to ensure
efficient sealing of the gasket.
[0026] As shown in fig. 2, lower drawing roller 74 may be positioned by means of an eccentric
device 75.
[0027] In this manner, both tapes 41 and 51 may be fed to respective guide channels 41b
and 51b, the mandrel end of which is comprised of a substantially pointed component
81 traversed by two channels 41b and 51b and capable of rotating around a fixed pin
82 to carry common outlet 81a of the two superimposed tapes 41 and 51 in a direction
tangential to ring 11 on which they are to be spirally wound. By means of such rotation
against the return action of a spring 83 it is possible for the direction of exit
of the tapes arriving from the feed units to be maintained at all times tangential
to gasket 5 which, during its formation, continuously increases its outside diameter
and correspondingly shifts the line of tangency.
[0028] In the synchronizing assembly are also provided components 76 and 77 for the cutting
of tapes 41 and 51, respectively operated by relevant pneumatic or like actuators
76a and 77a.
[0029] Synchronizing unit 70 is also provided with a device 90 (figs. 2 and 5) for regulating
the position of the entire unit 70 in a vertical sense with respect to the axis of
rotation of mandrel 3.
[0030] As illustrated schematically in fig. 5, such device is substantially comprised of
a screw 91 capable of being rotated via suitable means 91a made integral at its upper
free end and cooperating with nut 92 integral with plate 93 of unit 70.
[0031] Such regulation of entire unit 70 is necessary to make possible the initial alignment
of outlet 81a of pointed component 81 to the direction tangential to the outer circumference
of supporting ring 11 integral with mandrel 3, which circumference changes with the
change of the desired inside diameter of gasket 5 and therefore of the outside diameter
of supporting ring 11.
[0032] The operation of the machine is as follows:
Following programming of the operating sequence and setting of the values of the parameters
which determine the work cycle, arm 13 takes from reservoir 12 a ring 11 and positions
it on grippers 3a of mandrel 3 for locking and rotation.
[0033] There is then fed by driving wheel 73 steel tape 41 which, on passing through drawing
rollers 73, 74, is shaped as illustrated in figs. 4a, b, c then continues to run in
channel 41b until it reaches outlet 81a of pointed component 81 which has been previously
set, by regulating means 90, in a position tangential to ring 11.
[0034] Tape 41 is fed in a preset length capable of moving the leading edge of backing tape
41 from the cutter unit to the point of contact with ring 11.
[0035] Welding unit 30 is therefore moved upward until it comes into contact with backing
tape 41 against ring 11 and initiates the operation of welding between the two parts
(fig. 4b).
[0036] At this point, the backing tape becomes integral with ring 11.
[0037] Consequently from this moment the rotary movement of the mandrel drives backing tape
41, bringing about the rotation of rollers 73 and 74, 72 and 71 connected to roller
73.
[0038] After completing a preset number of turns of backing tape 41, the mandrel comes to
a halt. Cylinder 71b, by means of connecting rod 71a, places roller 71 in contact
with insulating tape 51 and shifts roller 65 against the action of spring 64, so that
when the mandrel is restarted the rotation of roller 73 brings about the synchronized
rotation of roller 71 and the consequent feed of insulating tape 51 in guide channel
51c toward outlet 81a, where it is superimposed on backing tape 41 at relative speed
zero. Thus the rotation of the mandrel brings about the simultaneous winding of both
tapes 41 and 51 so that each turn of insulating tape 51 is backed by high mechanical
strength tape 41.
[0039] On reaching a preset diameter, mandrel 3 comes to a halt, roller 71 which feeds sealing
tape 51 is moved away from the said tape by cylinder 71b and the tape is cut by relevant
means 76. This brings about stoppage of feed of sealing tape 51 to the gasket.
[0040] The mandrel restarts and winds the insulating tape 51 remaining in guide 51b together
with backing tape 41. After a present number of turns in which only backing tape 41
is wound, the mandrel comes to a halt, welding unit 30 is moved upward until it contacts
tape 41 wound on the gasket and cutting device 77 is actuated. Lastly, the mandrel
is caused to rotate and unit 30 carries out welding of the end of backing tape 41,
thus completing the gasket which in this way is perfectly matched both to the inside
diameter and to the outside diameter and is capable of maintaining such diametrical
dimensions.
[0041] Mandrel 3 then comes to a halt, units 20 and 30 return to their original positions
and grippers 3a release the inner ring from the gasket, which may then be unloaded
by an appendage of arm 13 and the machine then set for a further cycle.
[0042] Many variants may be introduced in the implementation of the parts comprising the
invention without thereby departing from the scope of protection of this patent as
described in the following claims.
1. An automatic machine for the production of gaskets (5) obtained by spiral winding
of tapes (41, 51) of different physical and mechanical characteristics on a supporting
ring (11), characterized in that it comprises means (13, 10) for feeding such supporting
rings (11) to a mandrel (3), a unit (20) exerting radial pressure on such rings (11),
a unit (30) for welding one of such tapes (41) to ring (11), a unit (40) for feeding
a tape (41) of high mechanical strength, a unit (50) for feeding a second tape (51)
of sealing material and a unit (70) for controlling and synchronizing the feed to
mandrel (3) of backing (41) and sealing (51) tapes interposed between respective feed
units (40) and (50), there being furthermore provided means for the relative movement
of feed unit (50) with respect to synchronizing unit (70) in a direction (Z-Z) transversal
to direction (Y-Y) of feed of tapes (41, 51) to mandrel (3), as well as means for
moving synchronizing unit (70) in a direction (X-X) normal to the other two directions
(Y-Y; Z-Z) for the alignment of the direction (Y-Y) of feed of tapes (41, 51) at a
tangent to the preset circumference of the gasket, and means (81, 83) for maintaining
such alignment as the outside diameter of the gasket increases with every revolution
of mandrel (3) during the formation of the said gasket.
2. An automatic machine according to claim 1, characterized in that such unit (40) for
the feeding of a tape (41) of high mechanical strength comprises a tensioning and
regulating device formed by an idle roller (42) for the return of tape (41), an arm
(43) having one end integral with the axis of rotation of roller (42) and swivelling
around it, and an idle return roller (44).
3. An automatic machine according to claim 1, characterized in that such unit (50) for
the feeding of a second tape (51) of sealing material is substantially comprised of
a shaped arm (52) carrying a pin (53), transversally to which may rotate a multiplicity
of reels (51a) of tape (51), such arm (52) being capable of overturning around a pin
(55) integral with synchronizing unit (70) and capable of moving with respect to the
latter in direction (Z-Z) transversal to direction (Y-Y) of feed of the tape, there
being also provided means (56a, 56b, 56c, 57a, 57b, 57c) for relative centring according
to both such directions and means (58, 58a, 58b) for the relative locking of the feed
unit and of the synchronizing unit.
4. An automatic machine according to claims 1 and 3, characterized in that such feed
unit (50) also comprises, for each reel (51a) of tape (51), a pulley (59) for the
return of the said tape made to rotate by a roller (60), from and toward which it
may be shifted by actuators (59c), on the front surface of which are provided slots
(59a) for monitoring the continuity of relative movement by means of a sensor (59g).
5. An automatic machine according to claim 1, characterized in that such unit (70) for
synchronizing backing (41) and sealing (51) tapes interposed between relevant feed
units (40) and (50) comprises a first roller (71) controlling the feed of tape (51)
on which act directly, when set to the operating position by positioning means (71b,
71a), means for controlling the rotation of roller (71) consisting of a driving roller
(73) connected to roller (71) by means of a toothed wheel (72) and a belt (72a), so
that such movement of roller (71) from/to the working position coincides with the
operation of deactivation of driving roller (73).
6. An automatic machine according to claim 1 and 5, characterized in that such driving
roller (73) constitutes a first roller of a pair of rollers (73, 74) through which
is fed tape (41), such pair of rollers also bringing about drawing of the said tape.
7. An automatic machine according to claim 1, characterized in that such means of movement
of feed unit (50) in direction (Z-Z) transversal to direction (Y-Y) of feed of tapes
(41, 51) to mandrel (3) are substantially comprised of a slide (57d) interposed between
shoulders (52).
8. An automatic machine according to claim 1, characterized in that such means for moving
synchronizing unit (70) in a direction (X-X) normal to the other two directions -
for the orientation of tapes (41, 51) according to a direction at a tangent to the
circumference of the gasket - are substantially comprised of screw assemblies (91)
integral with the frame of machine (1) and cooperating with a nut (92) integral with
the synchronizing unit.
9. An automatic machine according to claim 1, characterized in that such means (81, 83)
for maintaining such direction tangential throughout the formation of the gasket are
substantially comprised of a pointed component (81) within which are provided guide
channels (41a, 51a) for tapes (41, 51) discharging to an outlet (81a) for feeding
the mandrel, such point being capable of rotating around a pin (82) against the return
action of flexible means (83) and under the thrust action of the outer circumference
of the gasket (5) being formed.