PANEL PUNCH

Abstract: A panel punch (200) includes a main punch (232) to punch a trapezoidal opening in a panel (P) to receive an electrical chassis connector, and a secondary punch (234) integral with the main punch (232) and extending from each end (244, 246) thereof to punch a U-shaped slot in the panel extending from each end of the trapezoidal opening to receive mounting screws for physically attaching the electrical connector to the panel, characterised in that the maximum height of the secondary punch upper working surface (274) relative to the base (248) does not exceed the minimum height of the main punch inclined working surfaces (250, 252) and the height relative to the base (248) of the remote secondary punch end is less than the maximum height of the secondary punch inclined working surface (274).

Description: The invention relates to punch and die constructions and, in particular to punch and die constructions for punching holes in panels to receive articles such as electrical chassis connectors. U.S. Patent 4,481,7⊘⊘ issued November 13, 1984, to Larry Redmon, and corresponding to the pre-characterising part of claim 1, illustrates a panel punch and die set wherein the punch and die are connected together on opposite sides of a panel by a plurality of threaded bolts. A plurality of holes to receive the bolts must be drilled in the panel first, however. The punch and die are configured to punch a generally trapezoidal hole in the panel to receive the main body of the electrical chassis connector. However, holes for mounting screws to actually mount the connector on the panel must be drilled in separate operations following the punching operation. A panel punch and die set that requires drilling of only one pilot hole for a draw stud extending between the punch and die is illustrated in the Greenlee Tool Company catalogue August, 1985 at page 1⊘2 and designated RS-232 panel punch. The punch shown carries a portion to punch the trapezoidal opening in the panel and also carries a pair of lateral small round punch inserts releasably attached to the punch body, one on each side of the trapezoidal opening and separate therefrom, to punch a pair of circular holes, separate from the trapezoidal opening, in the panel for receiving the mounting screws for mounting the electrical connector panel. Although the panel punch shown in the catalogue performs satisfactorily in service, there is a need to reduce substantially the amount of force required to effect punching with that punch and die set. According to the present invention, there is provided a punch for punching an opening in a panel for an article comprising: a main punch having ends, a base, a pair of spaced apart lateral working surfaces and a pair of upper inclined working surfaces spaced from the base, the inclined working surfaces extending between the spaced apart lateral working surfaces, there being cutting edges between the spaced apart lateral working surfaces and the pair of upper inclined working surfaces, the inclined working surfaces each extending towards the base to a respective end of the main punch in diverging relation to one another and configured to punch the opening for receiving the article; at least one secondary punch having a pair of spaced apart lateral working surfaces and an upper working surface, the upper working surface extending between the spaced apart lateral surfaces and being configured for punching a secondary opening intersecting with and extending from the opening for receiving the article, the secondary opening being configured for receiving mounting means for attaching the article to the panel, the secondary punch extending from one of the respective ends of the main punch and terminating in a remote secondary punch end, and the secondary punch having the upper working surface thereof integrally interconnecting with an adjacent one of the inclined working surfaces of the main punch, the maximum height of the secondary punch upper working surface relative to the base not exceeding the minimum height of the main punch inclined working surfaces and the height relative to the base of the remote secondary punch end being less than the maximum height of the secondary punch inclined working surface, wherein the inclined working surfaces of the main punch each extending to their respective said end of the main punch, the secondary punch upper working surface being planar, and the inclined working surfaces of the main punch also being planar, characterised in that the angle of the main punch inclined working surfaces relative to the base is less than the angle of the secondary punch upper working surface relative to the base, and in that the secondary spaced apart lateral working surfaces are closer together than the main pair of spaced apart lateral working surfaces found on the main punch. Preferably, the main punch inclined working surfaces have an angle of 10° plus 5° or minus 2° relative to the base and the upper working surface of the secondary punch has an angle of 20° plus or minus 5° relative to the base. Furthermore, the main punch may have a secondary punch at each end of the main punch to punch secondary openings for mounting means at opposite ends of an article received in the opening punched by the main punch. A shaped bore configured to receive a draw stud may operatively connect said punch with a die, and the shaped bore may have a D-shaped cross-sectional profile. The punch may be combined with a die having a main cavity to receive the main punch and at least one secondary cavity extending from an end of the main cavity to receive the secondary punch. The punch may be combined with a die having a main cavity to receive the main punch and two secondary cavities extending from opposite ends of the main cavity to receive the secondary punches. A punch and die set that addresses this problem and effects a force reduction is described in FR-A 2600 564 to Larry G. Adleman and George P. Gill. The present invention will now be described with reference to Figures 1 to 7 of the accompanying drawings, in which:- Figure 1 is a perspective exploded view of the punch and die with a porion of panel that is to be punched; Figure 2 is a partial cross-sectional view of the assembled punch and die assembly of Figure 1 before penetration of the punch through the panel; Figure 3 is similar to Figure 2 after punch penetration; Figure 4 is a part-sectional end elevation of Figure 3 taken from the line 4-4 in Figure 2; Figure 5 is a plan view of the die taken from the lines 5-5 in Figure 2; Figure 6 is a plan view of the punch taken from the line 6-6 in Figure 2; and Figure 7 is a plan view of the punched panel. Figure 1 illustrates a punch and die set having a punch 10, die 12, draw stud 14 with attached head 14a, punch follow plate 16, die alignment plate 18 and nut 20. A portion of panel P to be punched is shown between the punch and die and includes a pilot hole H of a size to receive the draw stud. As shown in Figures 2-3, the punch and die are assembled in working relation on opposite sides of the panel in known fashion with the punch ultimately received in the die after the opening is punched. The punch 1⊘ includes a main punch 32 configured as shown to punch a general trapezoidal opening T (Figure 7) in panel P, and includes secondary punches 34 extending from opposite ends of the main punch 32 to punch generally U-shaped slots S intersecting with and extending from opposite ends of the trapezoidal opening, Figure 7. In particular, the main punch 32 includes lateral working surfaces 4⊘, 42 tapering slightly toward one another toward the surface 48 (Figure 4) and with surface 4⊘ shorter in length than surface 42 to provide the trapezoidal profile. The lateral working surfaces 4⊘, 42 are connected at opposite ends by end working surfaces 44, 46 which taper noticeably toward one another from lateral working surface 42 toward lateral working surface 4⊘ and from which the secondary punches 34 extend. Flat surface 48 interconnects working surfaces 4⊘, 42, 44, 46 on a side of the punch facing away from the die 12 when assembled. Inclined working surfaces 5⊘, 52 and flat, narrow working surface 54 are provided on the opposite side of the punch from surface 48. Inclined working surfaces 5⊘, 52 extend from flat working surface 54 in outwardly diverging relation toward the ends of the main punch and at equal angles relative thereto; e.g. about 24.1/2° relative to the plane of working surface 54 until they intersect the respective end working surfaces 44, 46. Of course, inclined working surfaces 5⊘, 52 also intersect the basically parallel lateral working surfaces 4⊘, 42 as shown. A bore or slot 6⊘ extends from surface 48 to flat working surface 54 of the punch to receive the draw stud 14 when the punch and die are assembled in working relation on opposite sides of panel P. To this end, the profile or cross-section of slot 6⊘ is complementary to that of the draw stud but slightly larger in dimension to provide a controlled clearance therebetween The slot 6⊘ has parallel sides 6⊘a connected by planar side 6⊘b and arcuate side 6⊘c as shown in Figure 6 to provide a D-shaped type slot profile so that the draw stud can only be inserted in one therethrough. Secondary punches 34 are integral with the main punch 32 and extend laterally in opposite directions from respective end working surfaces 44, 46. Each secondary punch 34 includes a surface 7⊘ extending from surface 48 of the main punch 32. Each secondary punch 34 also includes a working surface 72 extending from the respective end working surface 44, 46 and comprising planar lateral working surfaces 72a and radial end working surface 72b interconnecting the planar lateral surfaces 72a as shown in Figure 6. Radial surfaces 72b converge or taper slightly toward one another and toward surface 7⊘. Planar working surfaces 72a also converge or taper toward one another slightly in the direction toward the surface 7⊘. Facing opposite from surface 7⊘ is working surface 74 on each secondary punch 34. Each working surface 74 includes an outer working flat 74a and arcuate or radial working surface 74b extending from the flat 74a at the line of intersection 74c to and blended into the respective diverging inclined working surface 5⊘, 52 on that end. Radial working surface 74b is defined by radius R and extends into the respective inclined working surface as shown in Figure 2. It is apparent that arcuate working surface 74b of each secondary punch provides an arcuate recess between the flat working surface 74a and adjacent respective inclined working surface 5⊘, 52. Each arcuate recess faces away from surface 7⊘ toward the panel to be punched. The taper or convergence provided on the various working surfaces of the punch as well as on the die, function to aid in stripping the punched slug from the punch. As shown in Figures 2 - 5 the die 12 includes a main cavity 82 complementary in shape to the outer lateral profile of main punch 32 and secondary cavities 84 extending laterally from opposite sides of the main cavity and complementary in shape to the outer lateral profile of the respective secondary punches 34, except that the cavities 82, 84 are slightly larger in outer lateral or profile dimension so that the punches 32, 34 can be received with slight clearance therein during the punching operation. Outer lateral profile refers to the lateral and end working surfaces of punches 32, 34 described hereinabove. The internal working surfaces of the die 12 are provided with tapers generally complementary to the tapers on the lateral side working surfaces of punches 32, 34. Figures 1 - 3 illustrate the punch follower plate 16 which is positioned with its side 8⊘ against the punch surfaces 48, 7⊘ and includes a bore 85 shaped to receive the draw stud 14. The side 83 of the punch follower plate opposite to side 8⊘ thereof abuts draw stud head 14a when the punch and die set is assembled. Figures 1 - 4 show the die alignment plate 18 which is fastened to the side of the die oppositely disposed from the side thereof which faces the punch and abuts the panel when assembled for punching. The die alignment plate 18 includes diagonally disposed bores 9⊘ which receive machine screws 92 in turn threaded into threaded bores 94 in the die 12. Die alignment plate 18 includes a central bore 95 shaped top receive the draw dtud 14. The side 96 of the die alignment plate abuts nut 2⊘ on the draw stud when the punch and die is assembled. Draw stud 14 is shown in Figures 1 - 3 and includes opposite threaded ends 1⊘⊘ on which nut 2⊘ and draw stud head 14a are threaded as described hereinabove. An intermediate portion 1⊘2 is unthreaded. As mentioned hereinabove, the draw stud has a cross-sectional profile comprising parallel planar sides 1⊘6 interconnected by planar side 1⊘8 and arcuate side 11⊘ to define a general D-type profile so that the draw stud can be positioned in the bores of the punch, die, punch follower plate and die alignment plate in only one way. A punch and die set as described hereinabove has exhibited about a 25% reduction in the amount of force required to effect punching as compared to the force required for punching the same panel or material with the prior art punch RS-232 referred to hereinabove with no sacrifice in the quality of punched hole or opening produced. The substantial reduction in required punching force is largely due to the integration of the main punch 32 and secondary punches 34 into a unitary punch and to the blending and configuration of the working punch surfaces with and relative to one another. To effect punching once the punch and die set is assembled, the nut 2⊘ is turned on the draw stud by a wrench to cause the punch to penetrate through the panel and ultimately into the die as is known. The punch and die set described can also be driven with other devices, such as ball screw drivers and hydro-ram drivers, known in the art. The invention contemplates a panel punch of the general type claimed in U.S. Patent 4,724,616 wherein the configuration of the secondary punch is so related to that of the main punch as to produce a substantial further reduction in force required to force the punch through a panel. According to the present invention a punch basically similar to the punch 1⊘ differs inter alia in that the maximum height of the secondary punch working surface relative to the base does not exceed the minimum height of the adjacent main punch inclined working surfaces, and the height relative to the base of the extreme end of each secondary punch is less than the maximum height of the secondary punch working surface. An opening similar to the opening T shown in Figure 7 with slots S is also formed by the punch in accordance with the present invention, which will now be described with reference to the further accompanying drawings, in which:- Figure 8 is a view similar to Figure 2 of a punch in accordance with the invention, with a die and a portion of panel to be punched; and Figure 9 is a right end view of the punch of Figure 8. In Figures 8 and 9, the die 12, draw stud 14 with attached head 14a, punch follow plate 16, die alignment plate 18 and nut 2⊘ are the same as illustrated in Figure 2. Preceding descriptions applicable to those components in Figures 1 - 7 are also applicable in relation to Figure 8. The punch 2⊘⊘ in accordance with the invention includes a main punch 232 configured as shown to punch a general trapezoidal opening T (Figure 7) in panel P, and includes secondary punches 234 extending from opposite ends of the main punch 232 to punch generally U-shaped slots S intersecting with and extending from opposite ends of the trapezoidal opening, Figure 7. In particular, the main punch 232 includes lateral working surfaces 24⊘, 242 tapering slightly toward one another toward the surface 248 (Figure 9) and with surface 24⊘ shorter in length than the surface 242 to provide the trapezoidal profile. The lateral working surfaces 24⊘, 242 are connected at opposite ends by end working surfaces 244, 246 which taper noticeably toward one another from lateral working surface 242 toward lateral working surface 24⊘ and from which the secondary punches 234 extend. Flat surface 248 interconnects working surfaces 24⊘, 242, 244, 246 on a side of the punch 2⊘⊘ facing away from the die 12 when assembled. Inclined working surfaces 25⊘, 252 are provided on the opposite side of the punch from the surface 248. Inclined working surfaces 25⊘, 252 extend from a central apex 298 in outwardly diverging relation toward the ends of the main punch 232 and at equal angles relative thereto until they intersect the respective end working surfaces 244, 246. The inclined working surfaces 25⊘, 252 also intersect the basically parallel lateral working surfaces 24⊘, 242 as shown in Figure 9. It should also be appreciated that in an alternative embodiment of a punch in accordance with the invention, the apex 298 can be flattened to provide a narrow working surface such as working surface 54 illustrated in Figure 1. A bore or slot 26⊘ extends from the surface 248 to the upper surfaces 25⊘, 252 of the punch to receive the draw stud 14 when the punch and die are assembled in working relation on opposite sides of panel P. To this end, the profile or cross-secion of the slot 26⊘ is complementary to that of the draw stud but slightly larger in dimension to provide a controlled clearance therebetween. The slot 26⊘ has parallel sides connected by a planar side and arcuate side to provide a D-shaped type slot profile so that the draw stud 14 can only be inserted in one way therethrough to correspond with positioning of the draw stud in the other elements of the assembled device. The secondary punches 234 are integral with the main punch 232 and extend laterally in opposite directions from respective end working surfaces 244, 246. Each secondary punch 234 includes a surface 27⊘ extending from the surface 248 of the main punch 242. Each secondary punch 234 also includes a working surface 272 extending generally parallel to the longitudinal axis of the bolt 14 from the respective end working surface 244, 246. This surface 272 reverses itself in a radial bend and returns to the respective surface 244, 246 to form contours as illustrated in Figures 5, 6, and 7 for the slots S which are formed by the die. As is apparent upon examination, the primary difference between the punch 2⊘⊘ of Figures 8 and 9 and the punch 1⊘ of Figures 1 - 6 is in the upper working surfaces 274 of the secondary punches 234 as compared to the upper working surfaces 74 of the secondary punches 34. In Figure 8, it can be seen that the upper working surfaces 274 of the secondary punches 234 slope downwardly relative to the working surfaces 25⊘, 252 of the main punch 232 whereas in the punch of Figure 1, the secondary punches have working surfaces 74 which turn upwardly relative to the surfaces 5⊘, 52 of the main punch 32. In other words, the down-sloping angle 276 of the main punch working surfaces 25⊘, 252 is less than the angle 278 for the working surfaces 274 of the secondary punches 234. In accordance with the invention, the maximum height of the secondary punch inclined working surface 274 relative to the base 248 (or 27⊘) does not exceed the minimum height of the respective main punch inclined working surface 25⊘, 252, and the height relative to the base 248 of the extreme end of each secondary punch 234 is less than the maximum height of the secondary punch inclined working surface 274, i.e., less than the height of each secondary punch 234 at the junction with the respective end working surface 244, 246 of the main punch 232. To produce the very same cutout pattern in a panel P as illustrated in Figure 7, use of the punch 2⊘⊘ lowers the peak force that is required for punching the opening. Additionally, the total stroke is much reduced. Normally, when the stroke is reduced, the force increases in inverse proportion because the energy or work expended remains the same. When the main punch angle 276 is 1⊘° and the secondary punch angle 278 is 2⊘°, the stroke has been reduced to one half that required with the punch of Figure 1 without any increase in peak force and the energy or work expended has been reduced to 55% of that required by the punch of Figure 1. This is the result of a unique combination of the two angles 276, 278. Further, it has been found that if the angle 276 on the main punch is increased above 1⊘°, the peak force of first penetration into the panel P is lowered while the stroke is increased, but the force when the secondary punches become active is not reduced. If the main punch angle 276 is decreased below 1⊘°, the peak force due to the main punch is higher than the peak force produced by the secondary punches and this is undesirable. If the secondary punch angle 278 is reduced below 2⊘°, for example, to 1⊘°, making it a continuation of the main punch surface, the force required when the secondary punches become active is increased. If the secondary punch angle 278 is increased above 2⊘°, there is not a further reduction in peak force and stroke is unnecessarily increased. Thus, the combination of main and secondary angles is unique in achieving a minimum force and minimum energy from a functional standpoint. Although variations exist as the angles are changed, satisfactory performance is achieved over a range of punch sizes when the main punch angle 276 is in the range of 1⊘° plus 5° or minus 2° and the secondary punch angle 278 is in the range of 2⊘° plus or minus 5°. It is noteworthy that the angle on the main punch 32 in Figure 1 was in the order of 24.1/2°.

Claims: A punch (200) for punching an opening in a panel for an article comprising: a main punch (232) having ends (244, 246), a base (248), a pair of spaced apart lateral working surfaces (240, 242) and a pair of upper inclined working surfaces (250, 252) spaced from the base, the inclined working surfaces (250, 252) extending between the spaced apart lateral working surfaces (240, 242) there being cutting edges between the spaced apart lateral working surfaces (240, 242) and the pair of upper inclined working surfaces (250, 252), ; the inclined working surfaces (250, 252) each extending towards the base (248) to a respective end of the main punch (232) in diverging relation to one another and configured to punch the opening for receiving the article; at least one secondary punch (234) having a pair of spaced apart lateral working surfaces (272) and an upper working surface (274), the upper working surface (274) extending between the spaced apart lateral surfaces (272) and being configured for punching a secondary opening intersecting with and extending from the opening for receiving the article, the secondary opening being configured for receiving mounting means for attaching the article to the panel, the secondary punch (234) extending from one of the respective ends (244, 246) of the main punch and terminating in a remote secondary punch end, and the secondary punch having the upper working surface (274) thereof integrally interconnecting with an adjacent one of the inclined working surfaces (250, 252) of the main punch (232), the maximum height of the secondary punch upper working surface (274) relative to the base (248) not exceeding the minimum height of the main punch inclined working surfaces (250, 252) and the height relative to the base (248) of the remote secondary punch end being less than the maximum height of the secondary punch inclined working surface (274), wherein the inclined working surfaces (250, 252) of the main punch (232) each extending to their respective said end (244, 246) of the main punch, the secondary punch upper working surface (274) being planar, and the inclined working surfaces (250, 252) of the main punch (232) also being planar, characterised in that the angle of the main punch inclined working surfaces (250, 252) relative to the base (248) is less than the angle of the secondary punch upper working surface (274) relative to the base (248), and in that the secondary spaced apart lateral working surfaces (272) are closer together than the main pair of spaced apart lateral working surfaces (240, 242) found on the main punch (232). A punch as claimed in Claim 1, characterised in that the main punch inclined working surfaces (250, 252) have an angle of 10° plus 5° or minus 2° relative to the base (248) and the upper working surface (274) of the secondary punch (234) has an angle of 20° plus or minus 5° relative to the base (248). A punch as claimed in Claim 1 or Claim 2, characterised in that the main punch (232) has a secondary punch (234) at each end (244, 246) of the main punch to punch secondary openings for mounting means at opposite ends of an article received in the opening punched by the main punch (232). A punch as claimed in any one of Claims 1 to 3, further characterised by a shaped bore (260) configured to receive a draw stud (14) operatively connecting said punch (200) with a die (12). A punch as claimed in Claim 4, characterised in that the shaped bore (260) has a D-shaped cross-sectional profile. A punch as claimed in Claim 1 or Claim 2, characterised by being in combination with a die (12) having a main cavity (82) to receive the main punch (232) and at least one secondary cavity (84) extending from an end of the main cavity to receive the secondary punch (234). A punch as claimed in Claim 3, characterised by being in combination with a die (12) having a main cavity (82) to receive the main punch (232) and two secondary cavities (84) extending from opposite ends of the main cavity to receive the secondary punches (234).

Inventors: ADLEMAN, LARRY
Applicants: GREENLEE TEXTRON INC.
Application year: 1989
Main classification: B26F1
IPC codes: B26F1, B21D28