CA1184019A - Apparatus for joining sheet metal - Google Patents
Apparatus for joining sheet metalInfo
- Publication number
- CA1184019A CA1184019A CA000447428A CA447428A CA1184019A CA 1184019 A CA1184019 A CA 1184019A CA 000447428 A CA000447428 A CA 000447428A CA 447428 A CA447428 A CA 447428A CA 1184019 A CA1184019 A CA 1184019A
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- die
- punch
- opening
- sheet metal
- axis
- Prior art date
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Abstract
JOINING SHEET METAL
There is disclosed an improved apparatus for joining a plurality of pieces of sheet metal by first drawing and then laterally extruding the material to be joined into an enlarged shape which will permanently mechanically interlock the pieces. The apparatus utilizes a novel die construction in which portions thereof pivot laterally in response to lateral extrusion of the joining material, and is applicable to conventional "lanced" type joints as well as to a novel leakproof joint which is also disclosed. A method of forming a leakproof joint between a plurality of pieces of sheet metal is also disclosed.
There is disclosed an improved apparatus for joining a plurality of pieces of sheet metal by first drawing and then laterally extruding the material to be joined into an enlarged shape which will permanently mechanically interlock the pieces. The apparatus utilizes a novel die construction in which portions thereof pivot laterally in response to lateral extrusion of the joining material, and is applicable to conventional "lanced" type joints as well as to a novel leakproof joint which is also disclosed. A method of forming a leakproof joint between a plurality of pieces of sheet metal is also disclosed.
Description
The present invention relates generally to joining sheet metal and more particularly to an apparatus for forming such joints.
This is a division of copending Canadian Patent Application Serial No. 373 7 325, filed March 18, 1981.
Although it ls old in the art to join a plurality of pieces of sheet metal by punch-ing or otherwise manipulating same to cause them to be deformed into an interloking relationship in the localized area, insofar as applicant is aware such ~oints necessarily require the shearing oE mater-ial and hence are not suitable for leakproof applications (in the absence of some sealing material), and are destruc-tive of the corrosion resistance of coated materials. Known apparatus is also relatively complex in design, often requ.lring powered actuation of both a punch and portions of the dieg and utillzing expensively machined slidin~ die portions. This complexity lncreases the cost of the equip-ment, as well as the energy required i~or operation.
According to the present invention there is provided an apparatus for joining sheet metal, the apparatus having a punch with a given cross-section actuable for reciprocating movement along a Eirst axis and a die mounted in flxed aligned relationship to the punch. The die includes first and second die portions to dispose on opposite sides of the axis with means defining an opening in the die for receiving the punch when moved to the die, the opening being centered on the first axis and having a shape at least in part complimentary to the cross-sectional shape of the punch.
One portion of the opening is defined by one of the die portions an another portion of the opening defined by the other of the die portions. Pivot means mount the die portions mab/~
for pi~otal ~ovement with respect to one another about pivotal axis generally parallel to one another. The pivotal axis being disposed on opposite sides of and perpendicular to the axis. A fixed anvil is disposed in the opening against which the sheet metal is adapted to be pressed by the punch.
Other objects, features and advantages of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings.
BRIEF DRSCRIPTION OF THE DRA~INGS:
~igure 1 is a fragmentary front elevational view of an apparatus incorporating the principles of the present invent,ion, shown in its retracted position;
' Figure 2 is a Yiew similar to Fi~gure l but showing the apparatus in its advanced position;
Figure 3 is a view taken substantially along line 3-3 i,n Figure l;
Figure 4 is a fragmentary sectio~al view taken generally along line 4-4 in ~igure 3;
Figure 5 is a fragmentary sectional view taken generally along line 5-5 in Pigure 3;
Figure 6 is a perspectlYe v:Lew of the die body of the apparatus sho.wn in Figures 1-5;
Figure 7 is an enlarged fragmentary sectional view illustrating the leakproof joint at the point oE c~m-pletion of its formation by the apparatus;
Figure 8 illustrates dies for formi`ng a plura-lity of different shaped joints in accordance with the present invention;
Figure 9 is a partially e~ploded perspective 'view of an alternatiye form of a die assembly having universal mab/C~
applicability;
Figure 10 is a view of a universal punch assembly suited for use with the.die assembly of Figure 9;
Figure 11 is a fragmentary front elevational view of another embodiment of an apparatus incorporating th.e principles of the present invention which is applicable to the formation of conventional "lanced" ~ype joints;
~ Figure 12 is a side elevational view of the apparatus of Figure 11;
Figure 13 is a fragmentary enlarged sectional view of a "lanced" joint formed by the apparatus of Figures 11 and 12; and . Figllre 14 i~ a fragmentary sectional view taken generally along line 14-14 in Figure 13.
DETAILED DESCRIPTION OF T~IE PREFERRED.EMBODIMENTS
With reference to Figures 1-6, there is shown a sheet metal joînlng apparatus generally comprising a die assembly 10 and a punch assembly 12 for joining two pieces of sheet metal indicated at a and b, respectively. Although only two pieces of sheet metal are shown, it is to be understood that more than two pieces may be joined in accordance mab/~
~ ~ ~L~
..lth -the principles of the presen-t invention, depending upon the material in question and the thickness thereof. It is envisi.oned -that -the most common ma-terials to be joined by the present invention will include such materials as aluminum, gal-vanized, brass, steel, etc. sheet s-tock, both coated and uncoated.
The invention is particularly suitable for the joining of differ ent materials because they cannot be welded.
Punch assembly 12 is of conventional construction, including a punch body 14 mounti.ng a circular punch 16 and having a threaded portion 18 for threadably supporting a stripper retainer 20. Disposed within retainer 20 is a stripper 22 biased to the stripping position illustrated in Figure 1 by means of coil spring 24. Punch 16 preferably has a smoo-th flat tip, with a small radius at the edge as shown in Figure 7O
Die assembly 10 comprises cylindrical die body 26 mounted in the usual manner within a support structure 28 which may either be the lower leg of a conventional C-frame clamping device for use in a standard press, or the lower die supporting portion of a small press, such as a press of the type disclosed in applicant's Patent No. 3,730,044. Die body 26 is provided at its upper end (as shown) with an integral boss 30 from the opposite sides of which extend four shoulders, each indicated at 32.
Die body 26 is centrally bored and at the upper end thereof is provided a bore portion 34 in which is disposed (as by press fit) a hardened pin 36 which acts as an anvil or lower die member.
Pivotally supported on.each side of diç body 26, by means of roll pins 40 located in apertures 42, is a die por-tion 38. Each die portion 38 is generally T shaped in side elevation and is provided with two shoulders 44 engageable with two shoulders 32 on die body 26, so that vertical forces exerted on the die portions are transmitted directly to the die body and are not absorbed by pins 40. Each die portion 38 is relieved at 45 to lbb/,~ ~4~
mr . ~ . .
.~cili-ta-te limited rota-tional movement. Die portions 38 are mounted for pivotal movement between the respec-tive posi tions illustrated in Figures 1 and 2, and are maintained in a normally closed position, as shown in Figure 1, by means of a coil spriny 46 ac-ting between downwardly extending integral legs 48 on die portions 38. Spring 46 passes through a sui-table aper-ture 50 extending through boss 30.
When die portions 38 are in -their closed posi-tion illustrated in Figure 1, the upper surfaces 52 -thereof lie in a common horizontal plane and the abutting faces oE the die portions lie in a common vertical plane indicated at 54. In this embodiment die portions 38 are each provided with a com-plementary semi-circular recess 56 centered on plane 54 and defin.ing, when the die portions are in their closed position, an opening having a shape complementary to that of punch 16.
Forces exerted downwardly on die portions 38 by punch 16 acting on the workpieces will not tend to pivot them away from one another because the pivotal axes defi.ned by roll pins 40 are disposed outwardly of the edges of the opening defined by recesses 56. Thus any downward force exerted on the die portions by the punch will tend to close rather than open the die. In this embodiment the edge of the opening defined by recesses 56 should be chamfered, as indicated at 58 (Figures 1 and 7), to reduce the chance of fracturing or shearing the workpieces.
In operation, the apparatus is initially in the position illustrated in Figure 1. To join -two or more metal sheets they are first placed in overlapping or face-to-face relationship and thereupon placed into the apparatus in Figure 1, with the lower curface of the sheet metal assembly disposed on surfaces 52 of die portions 38. Thereafter the press (or whatever apparatus is used) is actuated to cause the punch -to b/~l ~5-ave downwardly (as shown) -towards sheet metal pieces a and b and die assembly 10. Upon engagement of die 16 and the sheet metal, -the lat-ter is caused to be drawn downwardly -toward -the upper surface of anvil 36, indicated at 60. There is no frac-turing or shearing of the me-tal because of -the provision of radius 58 around the periphery of the opening defined by recesses 56 and the clearance be-tween the lat-ter and the punch. The drawing action results directly from the coaction of the punch and the opening in die portions 38 defined by recesses 56. As punch 16 approaches anvil 36 at a dis-tance less than the total combined original thickness of sheet metal pieces a and b, there is a transverse or lateral extrusion of the metal, which results in the formation of a laterally enlarged shape, such as indicated at 62 in Figure 7, which defines a mechanical interlock be-tween sheet metal pieces a and b. Figure 7 is not drawn to scale, but is intended to provide a representative illustration of -the cross-sectional conEiguration of the metal forming the joint.
The lateral extrusion of sheet material causes die portions 38 to be forced laterally outwardly whereupon they pivo-t outwardly as best illustrated in Figures 2 and 7. A s-trong, permanent and leakproof joint having been formed, the punch is then with-drawn to the position illustra-ted in Figure 1 and the workpiece removed. It is noteworthy that in applicant's apparatus only punch 16 requires actuation, and anvil 36 remains fixed. Upon removal of the workpiece spring 46 causes die portions 38 to move back to their closed position illus-tra-ted in Flgure 1.
Shearing or lancing of -the sheet metal is avoided with the aforedescribed apparatus by providing radius 58 and an appropriate clearance between punch 16 and the opening defined by recesses 56. This clearance is preferably of uniform width.
Although applican-t has not conducted tests for op-timizing the lbb ~ -6-. ~, . . _ . __ _ . . ... , ..... , . ,.. , _. ~_ _.___.____. _.. . ,. , . .. __ .. _ .... ....... ... .
respective dimensions of the parts, se-t forth below are formulae which establish dimensions which have been found to provide very satisfactory resLllts:
P = 2 (Ml + M2) (+/- 20%) D = P + 0.8 (Ml + M2) T = 0.2 (1.2 (Ml ~ M2)) Where: P = punch diameter D = die diameter Ml = top metal thickness ~2 = bottom metal thickness ~ = total metal thickness at center of joint These rela-tionships have been found to be a satisfactory sta~t-ing point. Once the punch diameters are chosen and -the appara-tus assembled and tested, satisactory results can be obtained for the materials being joined by adjusting the bottom anvil height using the standard "shut height" ad~ustment (not shown) provided on conventional small presses and C-frames (i.e., the distance between the bottom of the punch and the anvil when the press is at the end of its downward stroke~.
Although the apparatus of the firs-t embodiment illustrates the use .of a circular punch other shapes may be used, depending upon the application and the s-trength requlred. For example, there are shown .in Figure 8 four different configura-tions which might be used. Die portions 38a are provided with three circular apertures 64 for those applications~in which either the anti-rotation characteristics or the strength charac-teristics desired require more than a single circular joint.
Die portions 38b have a diamond-shaped aperture 66 which is capable of providing a joint of strength comparable to that of the first embodiment, but yielding better anti-rotational characteristics. Die portions 38c have a triangular opening 68 lbb/~ _7_ ~ . . ......... ...... _ . .. . . .. .. ... .
which should give results similar to -those of -the diamond-shaped ~pening 60. Die por-tions 38d have on oval-shaped opening 70 providing a relatively large joint of high s-trength and high anti-ro-tational charac-teristics. Regardless of cross-sectional shape, the in-terior wall of the drawn portion of the upper piece of sheet metal will be generally cylindrical in configur-ation.
In Figure 9 there i9 illustrated a universal -type die body 26a which is virtually identical to die body 26 of the first embodiment but it provided with a plurality of parallel vertically aligned holes 72, 74 and 76 adapted to receive hard-ened anvil pins 78, 80 and 82, respectively, in a press fit relationship. It is envisioned that in applications where a single circular joint is sufficient, ~ins 78 and 82 may be removed from the die body, thus reducing energy requiremen-ts.
On the other hand, if greater strength or anti-rotation charac-teristics are desired, then one or two more addi-tional pins may be inserted in the proper hole to provide additional joining capability. The die portions which would be affixed to die body 26a would have a top configuration similar -to that shown at 38a in Figure 8, with openings 64 being designed to cooperate with pins 78, 80 and 82.
In Figure 10 there is illustrated the lower portion of a punch which may be utilized with the universal die body oE
Figure 9. The punch body, which can be conventional in all other respects, is indicated at 84 and is provided`with a plural-ity of press-Eit hardened steel punch pins 86, 88 and 90 adapted to coact with anvils 78, 80 and 82, respectively, in the same manner that punch 16 coacts with anvil 36 in the first embodi-ment. Suitable apertures 92 may be provided in the punch body84 to permit removal of the punches if it is desired to replace lbb/-l ~tb ame or reduce -the number thereof for a particular application.
The punch pins and anvils can be non-circular in cross-section if desired.
In Figures 11 and 12 there is illustrated a slightly modified version of the die assembly and punch which is capable of forming conventional "lanced" -type join-ts, such as illustra-ted in Figures 13 and 14. The die assembly lOa of this embodi men-t includes die body 26b and is subs-tahtially the s~me as die assembly 10 of the first embodiment (the same reference numerals are used to indicate identical parts), differing in -tha-t die portions 38e are not provided with recesses to de~ine a punch receiving opening, but instead are provided with cutting edges 94. In addition, the anvil comprises an integrally formed continuous flat generally horizontal surface 96 extending the full length of cutting edges 94. Punch l~a of this embodiment is generally spade-shaped, having a width substantially the same as the distance between cu-tting edges 94 and having cham-fered corners 98.
In Figures 13 and 14 sheet metal pieces c and d are shown joined utilizing the apparatus of Figures 11 and 12.
As the punch moves downwardly toward the die assembly, project-ions 100 and 102 are lanced out of sheet metal pieces c and d~
respectively. These projec-tions remain integrally attached to the parent metal at the ends thereof, as best shown :in Figure 13, but are totally s~vered Erom the material along their sides as shown at 104 in Figure 14. Continued advancemen~t of the punch toward the anvil causes a transverse or lateral extruding of projections 100 and 102 to create the enlarged section shown in Figure 14, which provides the necessary mechanical interlock to give the joint its in-tegrity. As will be appreciated, because there is a lancing of the sheet me-tal a joint of this type is not leakproof. As the metal of -the projections is extruded lbb/!~ 9 _ ~ .. __. .. _.. _.. ,. _ . . __ _ __ . _ _.. _ . . _ ~ . . ...
Laterally it causes die por-tions 38e to pivot apar-t to accommodate the extrusion and thereby define the interlock.
The use oE applicant's die assembly has been found -t~ very satisfactorily permit -the forma-tion o-f this type of joint with~
out the use of moving anvils and complex sliding dies.
Thus there is disclosed in the above descrip-tion and in the drawings an apparatus, method and joint which fully and ef:Eectively accomplish the objectives thereof; however, it will be apparent that variations and modifications of the disclosed embodiments may be made without departing from the principles of the invention or the scope of the appended claims~
lbb/~ -10-
This is a division of copending Canadian Patent Application Serial No. 373 7 325, filed March 18, 1981.
Although it ls old in the art to join a plurality of pieces of sheet metal by punch-ing or otherwise manipulating same to cause them to be deformed into an interloking relationship in the localized area, insofar as applicant is aware such ~oints necessarily require the shearing oE mater-ial and hence are not suitable for leakproof applications (in the absence of some sealing material), and are destruc-tive of the corrosion resistance of coated materials. Known apparatus is also relatively complex in design, often requ.lring powered actuation of both a punch and portions of the dieg and utillzing expensively machined slidin~ die portions. This complexity lncreases the cost of the equip-ment, as well as the energy required i~or operation.
According to the present invention there is provided an apparatus for joining sheet metal, the apparatus having a punch with a given cross-section actuable for reciprocating movement along a Eirst axis and a die mounted in flxed aligned relationship to the punch. The die includes first and second die portions to dispose on opposite sides of the axis with means defining an opening in the die for receiving the punch when moved to the die, the opening being centered on the first axis and having a shape at least in part complimentary to the cross-sectional shape of the punch.
One portion of the opening is defined by one of the die portions an another portion of the opening defined by the other of the die portions. Pivot means mount the die portions mab/~
for pi~otal ~ovement with respect to one another about pivotal axis generally parallel to one another. The pivotal axis being disposed on opposite sides of and perpendicular to the axis. A fixed anvil is disposed in the opening against which the sheet metal is adapted to be pressed by the punch.
Other objects, features and advantages of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings.
BRIEF DRSCRIPTION OF THE DRA~INGS:
~igure 1 is a fragmentary front elevational view of an apparatus incorporating the principles of the present invent,ion, shown in its retracted position;
' Figure 2 is a Yiew similar to Fi~gure l but showing the apparatus in its advanced position;
Figure 3 is a view taken substantially along line 3-3 i,n Figure l;
Figure 4 is a fragmentary sectio~al view taken generally along line 4-4 in ~igure 3;
Figure 5 is a fragmentary sectional view taken generally along line 5-5 in Pigure 3;
Figure 6 is a perspectlYe v:Lew of the die body of the apparatus sho.wn in Figures 1-5;
Figure 7 is an enlarged fragmentary sectional view illustrating the leakproof joint at the point oE c~m-pletion of its formation by the apparatus;
Figure 8 illustrates dies for formi`ng a plura-lity of different shaped joints in accordance with the present invention;
Figure 9 is a partially e~ploded perspective 'view of an alternatiye form of a die assembly having universal mab/C~
applicability;
Figure 10 is a view of a universal punch assembly suited for use with the.die assembly of Figure 9;
Figure 11 is a fragmentary front elevational view of another embodiment of an apparatus incorporating th.e principles of the present invention which is applicable to the formation of conventional "lanced" ~ype joints;
~ Figure 12 is a side elevational view of the apparatus of Figure 11;
Figure 13 is a fragmentary enlarged sectional view of a "lanced" joint formed by the apparatus of Figures 11 and 12; and . Figllre 14 i~ a fragmentary sectional view taken generally along line 14-14 in Figure 13.
DETAILED DESCRIPTION OF T~IE PREFERRED.EMBODIMENTS
With reference to Figures 1-6, there is shown a sheet metal joînlng apparatus generally comprising a die assembly 10 and a punch assembly 12 for joining two pieces of sheet metal indicated at a and b, respectively. Although only two pieces of sheet metal are shown, it is to be understood that more than two pieces may be joined in accordance mab/~
~ ~ ~L~
..lth -the principles of the presen-t invention, depending upon the material in question and the thickness thereof. It is envisi.oned -that -the most common ma-terials to be joined by the present invention will include such materials as aluminum, gal-vanized, brass, steel, etc. sheet s-tock, both coated and uncoated.
The invention is particularly suitable for the joining of differ ent materials because they cannot be welded.
Punch assembly 12 is of conventional construction, including a punch body 14 mounti.ng a circular punch 16 and having a threaded portion 18 for threadably supporting a stripper retainer 20. Disposed within retainer 20 is a stripper 22 biased to the stripping position illustrated in Figure 1 by means of coil spring 24. Punch 16 preferably has a smoo-th flat tip, with a small radius at the edge as shown in Figure 7O
Die assembly 10 comprises cylindrical die body 26 mounted in the usual manner within a support structure 28 which may either be the lower leg of a conventional C-frame clamping device for use in a standard press, or the lower die supporting portion of a small press, such as a press of the type disclosed in applicant's Patent No. 3,730,044. Die body 26 is provided at its upper end (as shown) with an integral boss 30 from the opposite sides of which extend four shoulders, each indicated at 32.
Die body 26 is centrally bored and at the upper end thereof is provided a bore portion 34 in which is disposed (as by press fit) a hardened pin 36 which acts as an anvil or lower die member.
Pivotally supported on.each side of diç body 26, by means of roll pins 40 located in apertures 42, is a die por-tion 38. Each die portion 38 is generally T shaped in side elevation and is provided with two shoulders 44 engageable with two shoulders 32 on die body 26, so that vertical forces exerted on the die portions are transmitted directly to the die body and are not absorbed by pins 40. Each die portion 38 is relieved at 45 to lbb/,~ ~4~
mr . ~ . .
.~cili-ta-te limited rota-tional movement. Die portions 38 are mounted for pivotal movement between the respec-tive posi tions illustrated in Figures 1 and 2, and are maintained in a normally closed position, as shown in Figure 1, by means of a coil spriny 46 ac-ting between downwardly extending integral legs 48 on die portions 38. Spring 46 passes through a sui-table aper-ture 50 extending through boss 30.
When die portions 38 are in -their closed posi-tion illustrated in Figure 1, the upper surfaces 52 -thereof lie in a common horizontal plane and the abutting faces oE the die portions lie in a common vertical plane indicated at 54. In this embodiment die portions 38 are each provided with a com-plementary semi-circular recess 56 centered on plane 54 and defin.ing, when the die portions are in their closed position, an opening having a shape complementary to that of punch 16.
Forces exerted downwardly on die portions 38 by punch 16 acting on the workpieces will not tend to pivot them away from one another because the pivotal axes defi.ned by roll pins 40 are disposed outwardly of the edges of the opening defined by recesses 56. Thus any downward force exerted on the die portions by the punch will tend to close rather than open the die. In this embodiment the edge of the opening defined by recesses 56 should be chamfered, as indicated at 58 (Figures 1 and 7), to reduce the chance of fracturing or shearing the workpieces.
In operation, the apparatus is initially in the position illustrated in Figure 1. To join -two or more metal sheets they are first placed in overlapping or face-to-face relationship and thereupon placed into the apparatus in Figure 1, with the lower curface of the sheet metal assembly disposed on surfaces 52 of die portions 38. Thereafter the press (or whatever apparatus is used) is actuated to cause the punch -to b/~l ~5-ave downwardly (as shown) -towards sheet metal pieces a and b and die assembly 10. Upon engagement of die 16 and the sheet metal, -the lat-ter is caused to be drawn downwardly -toward -the upper surface of anvil 36, indicated at 60. There is no frac-turing or shearing of the me-tal because of -the provision of radius 58 around the periphery of the opening defined by recesses 56 and the clearance be-tween the lat-ter and the punch. The drawing action results directly from the coaction of the punch and the opening in die portions 38 defined by recesses 56. As punch 16 approaches anvil 36 at a dis-tance less than the total combined original thickness of sheet metal pieces a and b, there is a transverse or lateral extrusion of the metal, which results in the formation of a laterally enlarged shape, such as indicated at 62 in Figure 7, which defines a mechanical interlock be-tween sheet metal pieces a and b. Figure 7 is not drawn to scale, but is intended to provide a representative illustration of -the cross-sectional conEiguration of the metal forming the joint.
The lateral extrusion of sheet material causes die portions 38 to be forced laterally outwardly whereupon they pivo-t outwardly as best illustrated in Figures 2 and 7. A s-trong, permanent and leakproof joint having been formed, the punch is then with-drawn to the position illustra-ted in Figure 1 and the workpiece removed. It is noteworthy that in applicant's apparatus only punch 16 requires actuation, and anvil 36 remains fixed. Upon removal of the workpiece spring 46 causes die portions 38 to move back to their closed position illus-tra-ted in Flgure 1.
Shearing or lancing of -the sheet metal is avoided with the aforedescribed apparatus by providing radius 58 and an appropriate clearance between punch 16 and the opening defined by recesses 56. This clearance is preferably of uniform width.
Although applican-t has not conducted tests for op-timizing the lbb ~ -6-. ~, . . _ . __ _ . . ... , ..... , . ,.. , _. ~_ _.___.____. _.. . ,. , . .. __ .. _ .... ....... ... .
respective dimensions of the parts, se-t forth below are formulae which establish dimensions which have been found to provide very satisfactory resLllts:
P = 2 (Ml + M2) (+/- 20%) D = P + 0.8 (Ml + M2) T = 0.2 (1.2 (Ml ~ M2)) Where: P = punch diameter D = die diameter Ml = top metal thickness ~2 = bottom metal thickness ~ = total metal thickness at center of joint These rela-tionships have been found to be a satisfactory sta~t-ing point. Once the punch diameters are chosen and -the appara-tus assembled and tested, satisactory results can be obtained for the materials being joined by adjusting the bottom anvil height using the standard "shut height" ad~ustment (not shown) provided on conventional small presses and C-frames (i.e., the distance between the bottom of the punch and the anvil when the press is at the end of its downward stroke~.
Although the apparatus of the firs-t embodiment illustrates the use .of a circular punch other shapes may be used, depending upon the application and the s-trength requlred. For example, there are shown .in Figure 8 four different configura-tions which might be used. Die portions 38a are provided with three circular apertures 64 for those applications~in which either the anti-rotation characteristics or the strength charac-teristics desired require more than a single circular joint.
Die portions 38b have a diamond-shaped aperture 66 which is capable of providing a joint of strength comparable to that of the first embodiment, but yielding better anti-rotational characteristics. Die portions 38c have a triangular opening 68 lbb/~ _7_ ~ . . ......... ...... _ . .. . . .. .. ... .
which should give results similar to -those of -the diamond-shaped ~pening 60. Die por-tions 38d have on oval-shaped opening 70 providing a relatively large joint of high s-trength and high anti-ro-tational charac-teristics. Regardless of cross-sectional shape, the in-terior wall of the drawn portion of the upper piece of sheet metal will be generally cylindrical in configur-ation.
In Figure 9 there i9 illustrated a universal -type die body 26a which is virtually identical to die body 26 of the first embodiment but it provided with a plurality of parallel vertically aligned holes 72, 74 and 76 adapted to receive hard-ened anvil pins 78, 80 and 82, respectively, in a press fit relationship. It is envisioned that in applications where a single circular joint is sufficient, ~ins 78 and 82 may be removed from the die body, thus reducing energy requiremen-ts.
On the other hand, if greater strength or anti-rotation charac-teristics are desired, then one or two more addi-tional pins may be inserted in the proper hole to provide additional joining capability. The die portions which would be affixed to die body 26a would have a top configuration similar -to that shown at 38a in Figure 8, with openings 64 being designed to cooperate with pins 78, 80 and 82.
In Figure 10 there is illustrated the lower portion of a punch which may be utilized with the universal die body oE
Figure 9. The punch body, which can be conventional in all other respects, is indicated at 84 and is provided`with a plural-ity of press-Eit hardened steel punch pins 86, 88 and 90 adapted to coact with anvils 78, 80 and 82, respectively, in the same manner that punch 16 coacts with anvil 36 in the first embodi-ment. Suitable apertures 92 may be provided in the punch body84 to permit removal of the punches if it is desired to replace lbb/-l ~tb ame or reduce -the number thereof for a particular application.
The punch pins and anvils can be non-circular in cross-section if desired.
In Figures 11 and 12 there is illustrated a slightly modified version of the die assembly and punch which is capable of forming conventional "lanced" -type join-ts, such as illustra-ted in Figures 13 and 14. The die assembly lOa of this embodi men-t includes die body 26b and is subs-tahtially the s~me as die assembly 10 of the first embodiment (the same reference numerals are used to indicate identical parts), differing in -tha-t die portions 38e are not provided with recesses to de~ine a punch receiving opening, but instead are provided with cutting edges 94. In addition, the anvil comprises an integrally formed continuous flat generally horizontal surface 96 extending the full length of cutting edges 94. Punch l~a of this embodiment is generally spade-shaped, having a width substantially the same as the distance between cu-tting edges 94 and having cham-fered corners 98.
In Figures 13 and 14 sheet metal pieces c and d are shown joined utilizing the apparatus of Figures 11 and 12.
As the punch moves downwardly toward the die assembly, project-ions 100 and 102 are lanced out of sheet metal pieces c and d~
respectively. These projec-tions remain integrally attached to the parent metal at the ends thereof, as best shown :in Figure 13, but are totally s~vered Erom the material along their sides as shown at 104 in Figure 14. Continued advancemen~t of the punch toward the anvil causes a transverse or lateral extruding of projections 100 and 102 to create the enlarged section shown in Figure 14, which provides the necessary mechanical interlock to give the joint its in-tegrity. As will be appreciated, because there is a lancing of the sheet me-tal a joint of this type is not leakproof. As the metal of -the projections is extruded lbb/!~ 9 _ ~ .. __. .. _.. _.. ,. _ . . __ _ __ . _ _.. _ . . _ ~ . . ...
Laterally it causes die por-tions 38e to pivot apar-t to accommodate the extrusion and thereby define the interlock.
The use oE applicant's die assembly has been found -t~ very satisfactorily permit -the forma-tion o-f this type of joint with~
out the use of moving anvils and complex sliding dies.
Thus there is disclosed in the above descrip-tion and in the drawings an apparatus, method and joint which fully and ef:Eectively accomplish the objectives thereof; however, it will be apparent that variations and modifications of the disclosed embodiments may be made without departing from the principles of the invention or the scope of the appended claims~
lbb/~ -10-
Claims (17)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Apparatus for joining sheet metal, comprising:
a punch having a given cross-section actuatable for reciprocating movement along a first axis; and a die mounted in fixed aligned relationship to said punch, said die including first and second die portions disposed on opposite sides of said axis, means defining an opening in said die for receiving said punch when moved to said die, said opening being centered on said first axis and having a shape at least in part complementary to said cross-sectional shape of said punch, one portion of said opening being defined by one of said die portions and another portion of said opening being defined by the other of said die portions, pivot means mounting said die portions for pivotal movement with respect to one another about pivotal axes generally parallel to one another, said pivotal axes being disposed on opposite sides of and per-pendicular to said first axis, and a fixed anvil disposed in said opening against which said sheet metal is adapted to be pressed by said punch.
a punch having a given cross-section actuatable for reciprocating movement along a first axis; and a die mounted in fixed aligned relationship to said punch, said die including first and second die portions disposed on opposite sides of said axis, means defining an opening in said die for receiving said punch when moved to said die, said opening being centered on said first axis and having a shape at least in part complementary to said cross-sectional shape of said punch, one portion of said opening being defined by one of said die portions and another portion of said opening being defined by the other of said die portions, pivot means mounting said die portions for pivotal movement with respect to one another about pivotal axes generally parallel to one another, said pivotal axes being disposed on opposite sides of and per-pendicular to said first axis, and a fixed anvil disposed in said opening against which said sheet metal is adapted to be pressed by said punch.
2. The apparatus as claimed in claim 1, wherein said pivotal axes are spaced apart a distance greater than the dimension of said opening in the same direction.
3. The apparatus as claimed in claim 1, further comprising spring means for biasing said die portions toward one another.
4. The apparatus as claimed in claim 1, wherein said opening is fully complementary in shape to the cross-sectional shape of said punch, and a uniform clearance is pro-vided between said punch and said opening to prevent shearing of said sheet metal when said punch is moved into said opening, said clearance being less than the total combined thickness of said sheet metal being joined.
5. The apparatus as claimed in claim 4, wherein said clearance is approximately 40% of said total combined thickness.
6. The apparatus as claimed in claim 1, wherein the edge of die opening facing said punch is provided with a radius to reduce the tendency of the apparatus to shear said sheet metal.
7. The apparatus as claimed in claim 1, wherein said opening has two sides which are substantially in alignment with corresponding sides of said punch so that said sheet metal is sheared when said punch is moved into said opening.
8. The apparatus as claimed in claim 1, further comprising a die body for pivotally supporting said die portions, and abutment means on said die body directly engageable with said portions to absorb the loads taken by said die portion as a result of actuation of said punch, thereby relieving said pivot means of said loads.
9. The apparatus as claimed in claim 1, further comprising a die body having a plurality of aligned holes disposed in perpendicular relationship to said axis, said anvil being disposed in one of said holes, the remaining holes being adapted to receive additional anvils for applications requiring multiple joints.
10. The apparatus as claimed in claim 1, wherein the free end of said punch and the free end of said anvil have generally flat opposed surfaces, respectively.
11. The apparatus as claimed in claim 10, wherein said flat surfaces are disposed generally parallel to one another.
12. The apparatus as claimed in claim 1, wherein the free end of said punch and said die opening are circular in cross-section.
13. The apparatus as claimed in claim 12, wherein the free end of said anvil is generally circular in cross-section.
14. The apparatus as claimed in claim 13, wherein the diameter of said anvil. is approximately the same as that of said die opening.
15. The apparatus as claimed in claim 15, wherein the diameter of said punch is less than the diameter of said die opening.
16. The apparatus as claimed in claim 15, wherein the difference between the diameters of said punch and die opening are less than the total combined thickness of said sheet metal being joined.
17. Apparatus for joining sheet metal, comprising:
a punch having a given cross-section actuatable for reciprocating movement along a first axis; and a die, said die including first and second die portions having generally planar surfaces engaging one another along a plane incorporating said first axis, means defining an opening in said die for receiving said punch when moved to said die, said opening being centered on said first axis and having a shape complementary to said cross-sectional shape of said punch, pivot means mounting said die portions for pivotal movement with respect to one another about pivotal axes generally parallel to one another, perpendicular to said first axis, said pivotal axes being spaced apart a dis-tance greater than the dimension of said opening in the same direction, a fixed anvil disposed in said opening against which said sheet metal is adapted to be pressed by said punch, and spring means for biasing said die portions toward one another.
a punch having a given cross-section actuatable for reciprocating movement along a first axis; and a die, said die including first and second die portions having generally planar surfaces engaging one another along a plane incorporating said first axis, means defining an opening in said die for receiving said punch when moved to said die, said opening being centered on said first axis and having a shape complementary to said cross-sectional shape of said punch, pivot means mounting said die portions for pivotal movement with respect to one another about pivotal axes generally parallel to one another, perpendicular to said first axis, said pivotal axes being spaced apart a dis-tance greater than the dimension of said opening in the same direction, a fixed anvil disposed in said opening against which said sheet metal is adapted to be pressed by said punch, and spring means for biasing said die portions toward one another.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US18495180A | 1980-09-08 | 1980-09-08 | |
| US184,951 | 1980-09-08 | ||
| CA000373325A CA1166832A (en) | 1980-09-08 | 1981-03-18 | Joining sheet metal |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000373325A Division CA1166832A (en) | 1980-09-08 | 1981-03-18 | Joining sheet metal |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1184019A true CA1184019A (en) | 1985-03-19 |
Family
ID=25669278
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000447428A Expired CA1184019A (en) | 1980-09-08 | 1984-02-14 | Apparatus for joining sheet metal |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1184019A (en) |
-
1984
- 1984-02-14 CA CA000447428A patent/CA1184019A/en not_active Expired
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| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |