U.S. patent application number 12/905234 was filed with the patent office on 2011-02-03 for apparatus and method for sealing a lidstock to a container.
Invention is credited to John R. Coppinger, Michael W. Murphy, Anthony O'Neill, Trevor F. O'Neill, Patrick J. Tobin.
Application Number | 20110024310 12/905234 |
Document ID | / |
Family ID | 36292819 |
Filed Date | 2011-02-03 |
United States Patent
Application |
20110024310 |
Kind Code |
A1 |
O'Neill; Trevor F. ; et
al. |
February 3, 2011 |
Apparatus and Method for Sealing a Lidstock to a Container
Abstract
The invention relates to a method for heat sealing a lidstock to
a container for a blister package, the container having a top
surface comprising a substantially flat sealing flange surrounding
a blister and a lip having at least one raised surface, the method
comprising the steps of a) locating the lidstock on the top
surface; b) providing a first seal between the lidstock and the at
least one raised surface of the lip with a first heat sealing tool;
c) providing a second hermetic seal between the lidstock and the
sealing flange surrounding the blister with a second heat sealing
tool. The invention also relates to a package for storing a
hydrophilic contact lens comprising a lip having at least one
raised surface and a removable lidstock sealed to a sealing flange
and to the at least one raised surface. Also disclosed is an
apparatus for heat sealing the lidstock to the container.
Inventors: |
O'Neill; Trevor F.;
(Tramore, IE) ; O'Neill; Anthony; (Tramore,
IE) ; Murphy; Michael W.; (Woodstown Upper, IE)
; Tobin; Patrick J.; (Waterford, IE) ; Coppinger;
John R.; (Gracedieu, IE) |
Correspondence
Address: |
Bausch & Lomb Incorporated
One Bausch & Lomb Place
Rochester
NY
14604-2701
US
|
Family ID: |
36292819 |
Appl. No.: |
12/905234 |
Filed: |
October 15, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12282174 |
Sep 9, 2008 |
7832188 |
|
|
PCT/EP2006/070117 |
Dec 21, 2006 |
|
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12905234 |
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Current U.S.
Class: |
206/205 ;
206/462; 206/5.1; 53/478 |
Current CPC
Class: |
B29C 66/242 20130101;
B65D 2585/545 20130101; B29C 66/924 20130101; B29C 66/8221
20130101; B29C 66/91231 20130101; B29L 2011/0041 20130101; B29C
66/72321 20130101; B29C 66/301 20130101; B29C 66/21 20130101; B29C
66/8324 20130101; B65B 7/2878 20130101; B29C 66/71 20130101; B29C
66/71 20130101; B29C 66/81415 20130101; B29C 66/131 20130101; B29C
66/30223 20130101; B29C 66/112 20130101; B29C 66/53461 20130101;
B29C 66/3452 20130101; B29C 66/81429 20130101; B29C 65/18 20130101;
B29C 66/944 20130101; B29C 66/244 20130101; B65D 77/2032 20130101;
B29C 66/8242 20130101; B29C 66/8167 20130101; B29C 66/8246
20130101; B29C 65/305 20130101; B29C 66/8432 20130101; B29C 65/76
20130101; B29C 66/91212 20130101; B29K 2023/12 20130101; B29L
2031/712 20130101 |
Class at
Publication: |
206/205 ;
206/5.1; 206/462; 53/478 |
International
Class: |
B65D 81/24 20060101
B65D081/24; A45C 11/04 20060101 A45C011/04; B65D 73/00 20060101
B65D073/00; B65B 51/10 20060101 B65B051/10 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 15, 2006 |
GB |
0605238.5 |
Claims
1. A package for storing a hydrophilic contact lens comprising: a
base having a top surface and a recess well having a perimeter in
the top surface for storing a hydrophilic contact lens, said top
surface comprising a substantially flat sealing flange surrounding
the recessed well and a lip having at least one raised surface; and
a removable lidstock sealed to said sealing flange and to the at
least one raised surface of said lip.
2. A package according to claim 1, wherein the lip has two mutually
spaced raised surfaces.
3. A package according to claim 1, wherein the lip has a curved
upper surface, curved downwards with respect to the sealing
flange.
4. A package according to claim 1, wherein the lip includes an
aperture.
5. A package according to claim 1, wherein the area of each raised
surface is 10 mm.sup.2 or less.
6. A package according to claim 1, wherein the base is a
thermoformable polypropylene polymer.
7. A package according to claim 1, wherein the lidstock is a
laminated foil comprising a metal layer and a basal thermoplastic
polymer layer.
8. A package according to claim 7, wherein the basal thermoplastic
polymer layer is polypropylene.
9. A package according to claim 1, further comprising a hydrophilic
contact lens and an aqueous solution contained in the recessed
well.
10. A package according to claim 1, especially a blister package
for contact lens.
11. A sealing apparatus for heat sealing a lidstock to a container
for a blister package, the sealing apparatus comprising a support
arm for supporting at least one sealing surface, the apparatus also
including means for heating said at least one sealing surface.
12. An apparatus as claimed in claim 11 wherein the at least one
sealing surface comprises an elongate sealing surface including a
plurality of spaced apart channels provided along the elongate
sealing surface, defining a plurality of sealing surfaces.
13. An apparatus as claimed in claim 12 wherein each of the
plurality of heated surfaces includes individual heating means for
individually heating each of the plurality of sealing surfaces.
Description
PRIORITY CLAIMS TO PRIOR APPLICATIONS
[0001] This application is a divisional of application Ser. No.
12/282,174, filed Sep. 9, 2008, which is the National Phase of
PCT/EP2006/070117, filed Dec. 21, 2006, which claims the benefit of
GB0605238.5, filed Mar. 15, 2006.
FIELD OF THE INVENTION
[0002] The invention is concerned with methods for sealing lidstock
to containers to form blister packages, particularly disposable
blister packages for contact lenses. The invention is further
concerned with a package for storing a hydrophilic contact
lens.
BACKGROUND OF THE INVENTION
[0003] Soft hydrogel contact lenses have been increasing in
popularity ever since they were first introduced in the 1970's.
Such contact lenses are conventionally packaged in the hydrated
state and in a storage solution. Currently, many contact lenses are
packaged, along with the aqueous storage solution, in a disposable
blister package typically formed from container of a rigid polymer
sealed with a lidstock. Examples of blister packages can be seen in
U.S. Pat. Nos. 4,691,820; 5,524,419; 5,578,331; 5,649,410;
5,722,536, 6,082,533 and WO2006/032829. The container forming the
base of a blister package can either be part of the original
contact lens mold or a separately molded base, typically formed
from a rigid polymer. In the above mentioned package types, the
container that holds the contact lens and any aqueous storage
solution, is sealed by a flexible lidstock. This lidstock is
typically a laminated foil which can be pulled back by a user to
access the lens contained in the blister of the container.
Typically, this lidstock is sealed to the area or flange of the top
surface of the container surrounding the blister. This sealing area
of the container is typically a substantially flat surface area, or
a raised flattened annular surface as seen, for example, in U.S.
Pat. No. 5,722,536. The preferred blister package with which the
method of the present invention is used is that disclosed in WO
2006/032829.
[0004] In order to facilitate the removal of the lidstock from the
package by the user, the top surface of the container is provided
with a lip spaced from the sealing flange on the top surface of the
package. The lidstock is left unsealed over part of this lip to
provide a finger lift such that the user may grasp the unattached
lidstock over the lip and use this portion to tear the lidstock
from the rest of the package in order to access the contents of the
blister.
[0005] Because the lidstock is not sealed to the lip, there may be
problems in handling and providing secondary packaging for the
disposable blister packages, as this unattached portion of the
lidstock is prone to being inadvertently folded back from the
lip.
[0006] There are also problems with the reliable positioning of the
lidstock over the container prior to forming the hermetic seal
around the blister, as the lidstock may become misplaced as the
package, prior to sealing, is moved between the different stations
of an automated packaging machine.
SUMMARY OF THE INVENTION
[0007] According to a first aspect of the invention, there is
provided a method for heat sealing a lidstock to a container for a
blister package, the container having a top surface comprising a
substantially flat sealing flange surrounding a blister and a lip,
the method comprising the steps of;
[0008] a) locating the lidstock on the top surface,
[0009] b) providing a first seal between the lidstock and a locus
of the lip with a first heat sealing tool,
[0010] c) providing a second hermetic seal between the lidstock and
the sealing flange surrounding the blister with a second heat
sealing tool.
[0011] The first seal is not over the entire lip, but only at a
locus of the lip such that the user may still grasp an unsealed
part of the lidstock to facilitate the removal of the lidstock from
the package.
[0012] The first seal has the advantages that the lidstock is held
in position immediately after placement of the lidstock before
being moved to the second sealing station for hermetic sealing of
the contents of the blister. It also gives the advantage that the
unsealed portion of the lidstock is less susceptible to accidental
folding back during subsequent processing of the package.
[0013] The method is particularly advantageous when the lip has a
curved upper surface, curved downwards with respect to the sealing
flange, in order to provide a gripping surface for the user when
opening the blister package. The first seal holds the lidstock in
place over the curved upper surface of the lip during subsequent
manufacturing process steps, but does not compromise the ease of
opening of the blister pack by the user, as there is still an
unsealed region of the lidstock over the lip for the user to
grasp.
[0014] The container is suitably moulded from a rigid polymer, for
example, a thermoplastic polymer such as polypropylene or
polystyrene. The container comprises a well or blister for holding
the material to be packaged, such as a soft contact lens with
hydrating solution, and has a flange around the well to which the
lidstock is sealed to form the sealed package. The flange may
simply be part of the top surface of the package itself, or may be
in the form of a raised area surrounding the well and provided on
the top surface of the package. The sealing surface of the flange
may be all or part of the upper surface of the rim, provided that
the sealing surface surrounds the blister such that when a seal is
made, the contents of the blister are hermetically sealed.
[0015] The container may start as a flat sheet of polymer and then
be moulded simply to form a well, leaving the remaining top surface
surrounding the blister as the flange of the well.
[0016] The container may be a more complex moulding such as that
disclosed in WO 97/28716 or WO 2006/032829, where the container is
provided with a plurality of legs and has a blister towards one end
of the surface of the container and a substantially flat lip region
towards the other end of the surface of the container. Preferably,
the container is that disclosed in WO 2006/032829.
[0017] Preferably, the lip of the container is curved downwards,
suitably in a smooth curve starting from near the flange and ending
towards an edge of the lip remote from the sealing flange. The lip
may be provided with a multiple curve, for instance having more
than one mutually orthogonal radii of curvature. The lip, whether
flat or curved, may also be provided with a hole or cutout to
facilitate lifting the lidstock from the lip by pushing through the
hole or cutout from below when the user wishes to open the blister
package.
[0018] The first seal is suitably at a locus spaced from the
sealing flange and spaced from an edge of the lip, such that there
is still an unattached portion of lidstock adjacent to the edge of
the lip to act as a finger lift allowing the user to grasp the
unattached portion to facilitate opening of the container.
[0019] It is preferred that the first seal has a fracture strength
which is less than the fracture strength of the second seal. If the
fracture strength of the first seal is greater than that of the
second seal, it may be difficult to exercise control when opening
the container, possibly leading to accidental spillage of contents.
Hence it is advantageous if the first seal has a fracture strength
which is less than that of the second seal to prevent such
spillage, requiring the user to increase the applied force in order
to open the second seal after the first seal has fractured. The
difference in the strength of the seals may be achieved by using a
pressure and/or temperature and/or contact time applied in forming
the first seal which is less than the pressure and/or temperature
and/or contact time applied in forming the second seal.
[0020] The first seal is simply a means of locating that portion of
the lidstock to the flange and it does not need to be a hermetic
seal.
[0021] In order to facilitate the tearing of the first seal, it is
preferred that the first seal comprises one or more mutually spaced
spot welds. By the term, "spot weld" is meant a weld in the form of
a small dot, suitably 10 mm.sup.2 or less in area, preferably 7
mm.sup.2 or less in area, more preferably 5 mm.sup.2 or less in
area. In order to provide ease of tearing combined with reliable
holding of the lidstock in place on the lip, it is preferred that
the first seal comprises at least two mutually spaced spot wells,
preferably consisting of two mutually spaced spot welds.
[0022] The first seal may be provided at a first station of a
packaging line, and the second seal provided at a second station of
the packaging line. Preferably, the first seal is provided at the
same station as the station where the lidstock is placed or located
on the top surface of the package, such that the risk of
displacement of the lidstock in subsequent movement is minimized.
The packaging line is preferably an automated packaging line.
[0023] In order for the first seal to be made, when the lip of the
container has a downwardly curved surface, it is preferred that the
first heat sealing tool comprises a sealing plate adapted to
contact the lidstock over the curved surface of the lip at a
tangent to provide the first seal. The sealing plate may be a flat
plate or may be provided with locally heated portions to provide
spot welds for the first seal.
[0024] Preferably, the first heat sealing tool is rotated about a
pivoting means such as an axle or hinge, to bring it into contact
with the lidstock over the raised surfaces of the lip to from the
first seal. This allows the placement and formation of the first
seal to take place conveniently at a single station.
[0025] The sealing plate of the first heat sealing tool is
preferably provided with a temperature sensor whereby the
temperature of the sealing plate during the formation of the first
seal may be monitored or controlled. This assists with the control
of the fracture strength of the first seal.
[0026] The second sealing tool for forming the second seal,
hermetically sealing the lidstock to the sealing flange of the
container suitably has a lower face which supports the container
directly below the flange, and an upper face which presses the
lidstock against the surface sealing surface of the flange of the
package. Typically, the upper face is heated, at least in the
sealing region, in order to provide a seal by melting a basal
thermoplastic layer of the lidstock to the sealing surface of the
rim.
[0027] According to a preferred embodiment of the method of the
invention, step (b) of the method includes the step of providing a
first seal between the lidstock and at least one raised surface
provided on the lip of the container.
[0028] Thus, the first seal is formed only at the at least one
raised surface of the lip. The method of the invention has the
advantage that it requires that the first sealing tool is at a
temperature which is lower than that heretofore required, thereby
prolonging the operating life of the tool. Furthermore, the method
of the invention results in minimized cosmetic damage to the
lidstock during formation of the first seal.
[0029] Ideally, the at least one raised surface is integrally
formed with the container.
[0030] Preferably, the lip has two mutually spaced raised
surfaces.
[0031] The provision of the raised surface(s) on the lip provides
the advantage that cosmetic damage to the lidstock laminated foil
is minimized during the first sealing operation because the first
heat sealing tool makes contact with a minimal surface area, namely
only the raised surfaces on the lip. This enables a reduction in
the operating temperature required for the first sealing operation
and so improves the operating life of the first heat sealing
tool.
[0032] According to a further aspect of the invention, there is
provided a package for storing a hydrophilic contact lens
comprising:
a base having a top surface and a recess well having a perimeter in
the top surface for storing a hydrophilic contact lens, said top
surface comprising a substantially flat sealing flange surrounding
the recessed well and a lip having at least one raised surface; and
a removable lidstock sealed to said sealing flange and to the at
least one raised surface of said lip.
[0033] Preferably, the lip has two mutually spaced raised surfaces.
The raised surfaces of the lip provide the advantages as described
previously for the first aspect of the invention.
[0034] Preferably, the lip of the container is curved downwards,
suitably in a smooth curve starting from near the flange and ending
towards an edge of the lip remote from the sealing flange. The lip
may be provided with a multiple curve, for instance having more
than one mutually orthogonal radii of curvature. The lip, whether
flat or curved, may also be provided with a hole or cutout to
facilitate lifting the lidstock from the lip by pushing through the
hole or cutout from below when the user wishes to open the
package.
[0035] The package may take the form of a blister package for
contact lens.
[0036] In a further aspect, the present invention provides a
sealing apparatus for heat sealing a lidstock to a container for a
blister package, the sealing apparatus comprising a support arm for
supporting at least one sealing surface, the apparatus also
including means for heating.
[0037] Preferably, the at least one sealing surface comprises an
elongate sealing surface including a plurality of spaced apart
channels provided along the elongate sealing surface, defining a
plurality of sealing surfaces.
[0038] Ideally, each of the plurality of heated surfaces includes
individual heating means for individually heating each of the
plurality of sealing surfaces.
[0039] The invention will now be further described, by way of
example only, with reference to the accompanying drawings, in
which:
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] FIG. 1 is a side view of a first embodiment of the first
seal being formed on a blister package;
[0041] FIG. 2 is a plan view of the top surface of a container
forming the base of a blister package showing the locations of the
first seal formed by spot welds in the first embodiment; and the
second seal, with lidstock removed;
[0042] FIG. 3 is a side view of a second embodiment of the first
seal being formed on a container;
[0043] FIG. 4 is a side perspective view of the container used in
the method shown in FIG. 3 with lidstock removed;
[0044] FIG. 5 is a rear view of the container of FIG. 4 with
lidstock removed;
[0045] FIG. 6 is a plan view of the top surface of the container of
FIGS. 4 and 5, forming the base of a blister package, with the
lidstock removed;
[0046] FIG. 7 is a top perspective view of the container of FIGS. 4
to 6, with lidstock removed;
[0047] FIG. 8 is a plan view of the top surface of the container as
shown in FIG. 6 but with the generally triangular-shaped raised
areas indicated;
[0048] FIG. 8a is a side view of the container of FIG. 8;
[0049] FIG. 9 is a perspective view of a first staking tool, in a
preferred embodiment, shown assembled;
[0050] FIG. 9a is a perspective view of the first staking tool
shown in FIG. 6, with the components of the staking tool shown
disassembled; and
[0051] FIGS. 10 and 10a are perspective views (corresponding to
FIGS. 6 and 6a respectively) of an alternative embodiment of first
heat sealing tool; the tool in this embodiment is similar to that
shown in FIGS. 6 and 6a except that the thermal staking head
includes holes in the embodiment shown in FIGS. 7 and 7a.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0052] Referring initially to FIGS. 1 and 2, a first embodiment of
the container is indicated generally by reference numeral 1. The
top surface of the container 1 is provided with a blister 2
surrounded by a sealing flange 3 where the second seal is located.
The lip 4 of the container is downwardly curved and is provided
with a hole 5. As shown in FIG. 2, the first seal is formed by two
spot welds 6.
[0053] FIG. 2 shows that the container 1 has legs 7,8 such as are
provided on the container described in WO 97/28716 and WO
2006/032829. The lidstock 9 is located over the top surface of the
container 1. The first heat sealing tool 11 is shown in FIG. 1 with
the sealing plate 10 in contact with the lidstock 9 over the curved
lip 4 so as to form the two spot welds 6 that provide the first
seal in the first embodiment. The first heat sealing tool includes
two individual electrical heating elements (not shown) for forming
the two spot welds 6. Two staking points 10a provided on the
sealing plate 10 are used to form the spot welds 6. The first heat
sealing tool 11 has a pivot 14 about which the whole tool can be
rotated by a pneumatic cylinder or a servo motor, and is further
provided with a heater 12 and a sensor 13 for monitoring the
temperature at the sealing plate.
[0054] In use, the first heat sealing tool is rotated from a rest
position remote from the container, about the pivot 14, by a
pneumatic cylinder or a servo motor, in direction A, until the
heated sealing plate 10, heated by the heater 12, comes into
contact with the lidstock 10 to form the first seal comprising the
two spot welds 6. After a predetermined time, the first heating
tool is then rotated back to its rest position. The package is then
relocated to the next station where the second seal is formed.
[0055] Referring now to FIGS. 3, 4, 5, 6, 7, 8 and 8a, a second
embodiment of the container is shown in which the first seal is
formed in an alternative way. The container in this second
embodiment is indicated generally by reference numeral 21. Like
features are indicated using like numerals.
[0056] The container 21 includes two raised surfaces 26, 26' which
are integrally formed on the container 21. The raised surfaces 26,
26' are approximately 2 mm.sup.2 in area. The container 21 and the
two raised surfaces 26, 26' are ideally formed of plastics
material, preferably polypropylene.
[0057] In FIG. 3, the first heat sealing tool 11' is shown with the
planar sealing plate 10' in contact with the lidstock 29 over the
two raised surfaces 26 provided on the curved lip 24 to form the
first seal. The first heat sealing tool 11' has a pivot 14' about
which the whole tool can be turned by a pneumatic cylinder or a
servo motor, in an arcuate movement in the directions A1, A2 of
arrow A. The first heat sealing tool 11' is provided with a heating
element 12' for heating the sealing plate 10' and a temperature
sensor 13' for monitoring the temperature of the sealing plate
10'.
[0058] In use, the first heat sealing tool is turned, from a rest
position remote from the container, about the pivot 14' by a servo
motor in direction A2 of arrow A, until the heated sealing plate
10', heated by the heating element 12', comes into contact with the
lidstock 29 over the two raised surfaces 26, 26' to form the first
seal. The first sealing tool applies an axial force to two spot
areas of the lidstock, in a direction tangential to the two raised
surfaces 26, 26' on the curved surface of the lip 24. The
aforementioned two spot areas of the lidstock are the areas located
immediately over the two raised surfaces 26, 26' on the lip 24 of
container 21. Thus, the first sealing tool forms a first seal
through the application of heat to the two mutually separate spot
areas of the lidstock which, during sealing, are sandwiched between
the sealing plate 10 and the two raised areas 26, 26' on the lip
24. The two raised surfaces 26, 26' at least partially melt as a
result of the heat applied by the sealing plate 10 and the melted
plastics material forms a seal between the lidstock and the
container 21. Thus, the raised surfaces 26, 26' are "sacrificial"
in the sense that they melt (at least partially) to form the first
seal between the lidstock and the container 21 without giving up
any of the body of the lip 24 and without causing any cosmetic
damage to the container 21. When the desired pressure and time is
reached at the set temperature as monitored by the sensor 13', the
arcuate movement of the heat sealing tool, in the direction of
arrow A2, is stopped and after a predetermined time, the first heat
sealing tool is then moved back to its rest position. The container
21 is then transferred to the next station where the second seal is
formed.
[0059] Referring now to FIGS. 9 and 9a, a preferred embodiment of
the first sealing apparatus for forming a first seal of the
lidstock to the curved lip 4 of the containers 1 and 21, is shown.
The first sealing apparatus can be used to form the first seal
comprising the spot welds on container 1 and can also be used to
form the first seal by melting the raised surfaces 26, 26' on the
container 21, thereby forming the seal between the lidstock and the
container 21.
[0060] As shown in FIGS. 9 and 9a, the apparatus is indicated
generally by reference numeral 50 and comprises a fixed arm 51, a
thermal staking head 52 having a ring 54 through which a pin 53 may
be inserted. The arm 51 functions as a support for the thermal
staking head 52.
[0061] Fitted longitudinally through the thermal staking head 52 is
a heating element 55. A thermocouple 56 is also included in the
assembly. The apparatus 50 also includes two insulators 58, one
insulator 58 provided at each side of the thermal staking head 52.
The apparatus 50 also includes four pan head bolts 59 for securing
the two insulators 58 to the thermal staking head 52. The tool 50
also includes a coiled cable holder 60, a shim 61, two dowels 62,
four bolts 63 as well as a circlip 64 (preferably of stainless
steel).
[0062] The thermal staking head 52 includes a plurality (four in
this preferred embodiment) of spaced apart channels 53 provided
transversely across the thermal staking head 52, thereby defining a
plurality of staking head sealing surfaces 52(a), 52(b), 52(c),
52(d) and 52(e).
[0063] Each of these staking head sealing surfaces 52(a), 52(b),
52(c), 52(d) and 52(e) provides a heated sealing plate so that the
apparatus 50 can be used to form the first seal on a plurality of
lidstocks on a plurality of containers 1, formed in an array. The
position of each of the five sealing surfaces 52(a), 52(b), 52(c),
52(d) and 52(e) is accurately positioned over an array of five
containers 1 by controlling the positioning of the sealing surfaces
52(a), 52(b), 52(c), 52(d) and 52(e) using the support arm.
[0064] Referring now to FIGS. 10 and 10a, an alternative embodiment
of sealing apparatus is shown. Like numerals are used to describe
like parts. The sealing apparatus in this embodiment is indicated
generally by reference numeral 70. The sealing apparatus 70 shown
in FIGS. 10 and 10a differs from apparatus 50 shown in FIGS. 9, 9a
in that the thermal staking head 72 of apparatus 70 includes a
raised shoulder portion 71 which includes a plurality of holes
which act as heat sinks.
[0065] Another difference between apparatus 50 and apparatus 70 is
that the ring 55 on the staking head 52 is replaced by a hole 75 on
the shoulder 71 through which pin 74 may be inserted.
[0066] It is to be understood that the invention is not limited to
the specific details described above which are given by way of
example only and that various modifications and alterations are
possible without departing from the scope of the invention, as
defined in the appended claims.
* * * * *