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Title:
ELONGATED METAL TAPE FOR FORMING ELECTRICAL CONTACTS
Document Type and Number:
WIPO Patent Application WO/1999/004404
Kind Code:
A1
Abstract:
The present invention provides elongated metal tapes (10) which can be severed into multiple rivet-type electrical contacts. The tapes (10) include an elongated head (12) and an elongated body (14) which form a contact head and a contact body when the tape (10) is severed without a cold heading operation. The tapes (10) are designed such that the body of the contact is deformed when the contact is secured to a workpiece such as a metal stamping. The metal tapes (10) can be fed directly into a progressive die used to make the stamping, and severed into contacts and secured to the stamping within the die.

Inventors:
ZALESKI MITCHELL (US)
Application Number:
PCT/US1998/001263
Publication Date:
January 28, 1999
Filing Date:
January 20, 1998
Export Citation:
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Assignee:
PYLON TOOL CORP (US)
ZALESKI MITCHELL (US)
International Classes:
H01H1/06; H01H11/04; (IPC1-7): H01H1/02; B32B1/00; B32B15/20
Foreign References:
US0326152A1885-09-15
US2711577A1955-06-28
US3667110A1972-06-06
US4475983A1984-10-09
US5175927A1993-01-05
Other References:
"CLAD PRECIOUS METALS FOR TODAY'S ELECTROMECHANICAL AND ELECTRONIC PRODUCTS", CLAD PRECIOUS METALS FOR TODAY'S ELECTROMECHANICAL AND ELECTRONIC PRODUCTS, XX, XX, 9 July 1992 (1992-07-09), XX, pages COMPLETE, XP002913446
Attorney, Agent or Firm:
Jones III, Harry C. (1155 Avenue of the Americas New York, NY, US)
Download PDF:
Claims:
WE CLAIM AS OUR INVENTION:
1. An elongated metal tape for use in making rivettype electrical contacts securable to a workpiece comprising: an elongated tape head extending along a first direction; an elongated tape body extending from the tape head and along the first direction; and a shoulder formed at the junction of the tape head and tape body; wherein the metal tape is severable into multiple rivettype electrical contacts such that the tape body of the severed contact is insertable into an opening in the workpiece with the shoulder abutting the workpiece and the tape body being deformable to secure the contact to the workpiece against the shoulder.
2. The elongated metal tape of claim 1 wherein the tape head has a width and the tape body has a width which is less than the width of the tape head.
3. The elongated metal tape of claim 2 wherein the shoulder is defined by the relative widths of the tape head and the tape body.
4. The elongated metal tape of claim 1 wherein the tape has a Tshape in crosssection.
5. The elongated metal tape of claim 1 wherein the tape head and tape body are made from a single type of material.
6. The elongated metal tape of claim 1 wherein the material is selected from the group consisting of silver, copper, gold or alloys thereof.
7. The elongated metal tape of claim 1 wherein the tape is severable into multiple rectangularly shaped contacts.
8. The elongated metal tape of claim 1 wherein the tape is severable into multiple contacts having a round shape.
9. The elongated metal tape of claim 1 wherein the tape has a series of spaced apart webs defined by and positioned between holes through the tape created when the tape is severed to form the contacts.
10. The elongated metal tape of claim 1 having spaced apart locations along a length of the tape wherein the tape is severable at the spaced apart locations such that each location defines opposing sides of first and second adjacent contacts.
11. The elongated metal tape of claim 1 wherein the tape head and the tape body are made from different materials.
12. The elongated metal tape of claim 11 wherein the tape head and tape body are welded together.
13. The elongated metal tape of claim 1 wherein the tape head comprises an elongated inlay carrier having a recess extending along the first direction and an elongated inlay positioned in the recess.
14. The elongated metal tape of claim 13 wherein the inlay carrier further comprises first and second rails on opposing sides of the inlay.
15. The elongated metal tape of claim 1 wherein the tape body is aligned substantially along a centerline of the tape head.
16. The elongated metal tape of claim 1 further comprising an elongated layer of conductive material bonded to the tape head.
17. An elongated metal wire for use in making rivetable electrical contacts comprising: a head having first and second opposed wings extending laterally outward from the head; a deformable body depending from the head between the first and second wings such that the first and second wings extend laterally beyond first and second opposed sides of the body; and a first shoulder formed by the first wing and the first side of the body and a second shoulder formed by the second wing and the second side of the body; wherein the wire is severable into multiple contacts.
18. The elongated metal wire of claim 17 wherein the head comprises a carrier having a recess and an inlay bonded to the head within the recess.
19. The elongated metal wire of claim 17 wherein the body and at least a portion of the head are made from different metal materials.
20. An elongated metal tape for use in making rivettype electrical contacts comprising: an elongated base defining a recess extending along a longitudinal length of the base; and an elongated inlay bonded to the base in the recess; wherein the metal tape is severable into multiple rivettype electrical contacts.
21. The elongated metal tape of claim 20 wherein the base comprises first and second rails on opposite sides of the inlay.
22. The elongated metal tape of claim 20 wherein the base and the inlay are selected from the group consisting of silver, copper, gold or alloys thereof.
23. The elongated metal tape of claim 20 wherein the tape is severable into multiple rectangularly shaped contacts.
24. The elongated metal tape of claim 20 wherein the tape is severable into multiple contacts having a round shape.
25. The elongated metal tape of claim 20 wherein the tape has a series of spaced apart webs defined by and positioned between holes through the tape created when the tape is severed to form the contacts.
26. The elongated metal tape of claim 20 having spaced apart locations along a length of the tape wherein the tape is severable at the spaced apart locations such that each location defines opposing sides of first and second adjacent contacts.
Description:
SPECIFICATION TITLE: "ELONGATED METAL TAPE FOR FORMING ELECTRICAL CONTACTS"

FIELD OF THE INVENTION The present invention generally relates to elongated metal tapes used to make rivet-type electrical contacts and the rivet-type contacts made from the tapes.

BACKGROUND OF THE INVENTION Electrical contacts have been used as components in electrical switches in a wide range of devices. The contacts are electrically conductive and provide a contact which can be brought into and out of contact with another switch component to close and open the switch. The electrical contact is typically attached to another piece of electrically conductive metal, such as a metal stamping made by a punch press machine.

One existing method of attaching electrical contacts to metal stampings is by welding the two parts together. The strength of the bond and the electrical connection between the welded parts is dependent on the integrity of the weld

joint. The electrical conductivity and the strength of the bond between the two parts are affected by the extent that the two parts are fused together during the welding process. The welding operation commonly occurs in a welding machine which is separate from the punch press used to make the metal stamping.

Another method of attaching an electrical contact to a metal stamping is by riveting a rivet-type contact into the stamping. The small end of the rivet-type contact is inserted into a hole in the metal stamping and staked or upset to retain the contact in the stamping.

These rivet type contacts are made by cold heading specialists. They have machines which take ordinary round wire and cut off and upset, or cold head, the large diameter of the rivet-type contact. Most manufacturers do not have the expertise or the equipment to make rivet-type contacts, consequently this is normally a purchased component.

SUMMARY OF THE INVENTION The present invention provides elongated metal tapes to make rivet-type contacts. This eliminates the need to purchase or to make rivet-type contacts using the cold heading operation. The elongated metal tapes are severable into multiple rivet-type contacts. The structure of the tapes provide rivet-type contacts which already have a contact head formed on the contact. The severing into multiple rivet-type contacts will occur in the progressive die which is making the

stamping and in addition will make and insert its own contact from the elongated metal tape. Accordingly, the cold heading operation commonly used to make the rivet-type contacts is eliminated.

The elongated tapes have a relatively wide head and a relatively narrow body extending from the head. A tape is severed into multiple rivet-type contacts having a contact head and a deformable contact body. The contact body is inserted into a hole in the metal stamping and the contact head abuts the stamping because it is larger than the hole. The contact body is deformed to secure the contact to the stamping and at this time if desired the head side of the contact may be modified by coining to provide a spherical or conical surface, for example, which is often desired. Elongated tapes contemplated by this invention can be made having a variety of cross-sectional shapes. A preferred tape, however, is T- shaped in cross-section.

The elongated tape can be severed into contacts having any desired shape when viewed from above the contact head, such as rectangular, oval or round, for example. The tape can be formed out of one or more electrically conductive materials, for example, silver, gold, copper and alloys of these materials. A portion of the tape and contact can be made from silver to improve an electrical connection made by the contact while the remaining portion of the tape and contact can be made from copper to reduce material costs.

The inventive elongated metal tapes and rivet-type contacts reduce manufacturing processes and costs because a cold heading operation is not needed to form the head. Further, the tapes can be fed directly into a progressive die used to make the metal stampings. The tape can be severed into contacts and the contacts secured to the stamping all in the die. Thus, the new elongated tapes provide improved rivet-type contacts and efficient methods to make the contacts and assemble the contacts to a workpiece such as a metal stamping.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of an elongated metal tape of the present invention.

Figure 2 is a cross-sectional view of a rivet-type contact made from the tape of Figure 1 and secured to a metal stamping.

Figure 3 is a perspective view of a rectangular rivet-type contact formed from the tape of Figure 1, deformed and with the metal stamping removed.

Figure 4 is a perspective view of the tape of Figure 1 showing an outline of round rivet-type contacts severable from the tape.

Figure 5 is a perspective view of the round contact of Figure 4, deformed and with the metal stamping removed.

Figure 6 is an end view of another elongated metal tape of the present

invention showing the tape made from two distinct materials.

Figure 7 is a perspective view of another elongated metal tape of the present invention in which the tape is formed from two types of metal materials.

Figure 8 is a perspective view of a rectangular rivet-type contact formed from the tape of Figure 7, deformed and with the metal stamping removed.

Figure 9 is a perspective view of another elongated metal tape of the present invention showing an inlay in a head of the tape.

Figure 10 is a perspective view of a rectangular rivet-type contact formed from the tape of Figure 9, deformed and with the metal stamping removed.

Figure 11 is a perspective view of the tape of Figure 9 showing an outline of round rivet-type contacts severable from the tape.

Figure 12 is a perspective view of the round contact of Figure 11, deformed and with the metal stamping removed.

Figure 13 is a perspective view of another elongated metal tape of the present invention after rectangular rivet-type contacts have been severed from the tape.

Figure 14 is a perspective view of the rectangular rivet-type contact formed from the tape of Figure 13, deformed and with the metal stamping removed.

Figure 15 is a perspective view of the tape of Figure 13 after round rivet-

type contacts have been severed from the tape.

Figure 16 is a perspective view of the round rivet-type contact formed from the tape of Figure 15, deformed and with the metal stamping removed.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Although the present invention can be made in many different forms, the preferred embodiments are described in this disclosure and shown in the attached drawings. This disclosure exemplifies the principles of the present invention and does not limit the broad aspects of the invention only to the illustrated embodiments.

An elongated metal tape or wire 10 made accordingly to the present invention is shown in Figure 1. The tape 10 has an elongated tape head 12 and an elongated tape body 14 extending from the head 12. Preferably, the tape body 14 extends from the tape head 12 substantially along a centerline of the tape head 12.

Two opposed wings 16 extend laterally outward from the tape head 12 and away from the tape body 14. Two shoulders 18 are formed at the junction of the tape head 12 and the tape body 14. The tape head 12 has a greater width than the tape body 14 and the difference in widths forms the shoulders 18. The tape 10 is T- shaped in cross-section because of the relative widths of the tape head 12 and tape body 14, and because of the wings 16 and the shoulders 18. However, the tape 10

could have other desired cross-sectional shapes depending on the shapes and sizes of the tape head 12 and the tape body 14 and the location that the body 14 is connected to the tape head 12.

The elongated metal tape 10 can be severed at desired spaced apart locations along its length to form rivet-type electrical contacts. Rectangularly shaped contacts can be formed by severing the tape 10 transversely relative to the longitudinal length of the tape 10. The tape 10 is formed from a single type of metal material, such as silver. Other materials suitable for electrical contacts can also be used, for example, copper, gold and alloys of these materials. When the tape 10 is severed into a rivet-type contact, the tape head 12 and the tape body 14 become a head and body of the contact, respectively. A tape head contact surface 20 forms the electrical contact surface on the rivet-type contact.

A rivet-type contact 22 made from the tape 10 and secured to a metal stamping or workpiece 24 is shown in Figure 2. The stamping 24 has a hole 26 into which the contact 22 is inserted. A body 14a of the contact 22 is deformed during a staking operation to secure the contact 22 to the stamping 24. The stamping 24 is secured between a contact head 12a and the deformed body 14a, and is adjacent two wings 16a and shoulders 18a. Referring to Figure 3, the contact 22 is shown with the stamping 24 removed. In this embodiment, the tape 10 has been severed such that the contact 22 has the rectangularly shaped contact

head 12a and contact surface 20a. The contact head 12a and contact surface 20a can be formed into a spherical, conical or other shape when the contact 22 is staked to the stamping 24. In other words, the contact head 12a and the contact surface 20a achieve their size and shape after the contact 22 is secured to the stamping 24 with the contour best suited to the application.

Multiple contacts 22 are made by severing the tape 10 (Figure 1) at spaced apart locations along the tape 10 such that each severing location defines opposing sides of adjacent contacts. Waste material from the process of severing the tape 10 into contacts can be minimized by severing the tape such that the contacts are adjacent each other on the tape prior to severing. The tape 10 can be severed into rivet-type contacts having any desired head shapes. For example, Figures 4 and 5 show a round outline 26 of a round shaped contact 28. The round shaped contact 28 is shown in Figure 5 after the contact body 30 is deformed with the metal stamping removed. The round shaped contact head 32 can be formed into a spherical, conical or other shape when securing the contact 28 to the stamping.

An end view of another elongated tape 34 according to the present invention is shown in Figure 6. This embodiment is similar to the tape 10 of Figure 1, except a contact layer 36 is bonded to the head 38 forming a composite tape. The tape contact layer 36 is made from a different material than the rest of

the head 38 and the body 40. For example the contact layer 36 can be made from silver and the remaining portion of the tape 34 can be made from copper. The composite tape 34 produces contacts having the benefits of a silver contact surface 42 while reducing costs by making the rest of the contact from copper.

Another elongated tape 44 and rivet-type contact 46 according to the present invention are shown in Figures 7 and 8. The tape 44 has a tape head 46 bonded to a tape body 48 which are made from different materials. For example, the tape head 46 can be silver and the tape body 48 copper, forming a composite tape. The body 48 can be bonded to the tape head by any method acceptable for making electrical contacts, for example edge welded or fused. The composite 46 is shown in Figure 8 as rectangular and with the stamping removed. However, the tape 44 can be severed into any desired contact shape.

Another elongated tape 50 and rivet-type contact 52 according to the present invention are shown in Figures 9 and 10. The tape 50 is a composite tape and has a tape head 54 defining an elongated recess 56 and a tape body 58 extending from the tape head 54. An elongated inlay 60 is bonded to the head 54 in the recess 56. The tape head 54 has opposing rails 62 on either side of the inlay 60. The materials of the inlay 60 and the remaining portion of the tape 50 are different from each other, such as a silver inlay 60 with the remaining portion of the tape being made of copper. The composite tape 50 can be severed into

rectangular rivet-type contacts 52 as shown in Figure 10. The tape 50 is severed such that the inlay 60 forms a contact head 64 and the rails 62 remain as part of the tape 50. In this manner, the tape head 54 with the rails 62 forms a carrier for the inlay 60. Figure 11 shows the tape 50 of Figure 9 with a round outline 64 of a round shaped contact 66. The round shaped contact 66 is shown in Figure 12 after being deformed with the stamping removed. Severing the round shaped contact 66 from the tape 50 may leave webs 68 in the tape 50 after the contacts 66 are blanked from the tape.

Another elongated metal tape 70 according to the present invention is shown in Figures 13 and 15. Figure 13 shows the tape 70 after rectangularly shaped contacts 72 (Figure 14) have been severed from the tape 70, and Figure 15 shows the tape 70 after round shaped contacts 74 (Figure 16) have been severed from the tape 70. The tape 70 includes an elongated base having a mid-portion 78 and rails 80 on opposite sides of the mid-portion 78. An elongated recess 82 extends along the length of the base 76. An elongated inlay 84 is bonded to the base 76 in the recess 82. The inlay 84 and the base 76 are made from materials suitable for electrical contacts such as silver, copper, gold and alloys of these metals. For example, the base 76 can be copper and the inlay 84 silver.

Various shapes of contacts can be made from the tape 70. For example, the rectangular and round shaped contacts 72,74 shown in Figures 14 and 16.

The rectangularly shaped contacts 72 can be severed from the tape 70 on three sides and adjacent to each other (Figure 13) such that the rails 80 remain connected to the tape 70. The locations on the tape 70 where the contacts are severed can be spaced further apart to leave webs 86 and holes 88 as shown in Figure 15. As shown in Figures 14 and 16, the inlay 84 forms outer surfaces 90, 92 on the contacts 72,74. The outer surfaces 90,92 are brought into contact with other electrically conductive elements (not shown) to complete an electrical connection. The heads of the contacts 72,74 can be deformed during the process of securing the contacts to a stamping. The elongated metal tape 70 is the carrier to deliver the silver inlay 84 to where it can be utilized as a contact. This variation does not necessarily require the T-shape. The straight walled cut-off from the tape 70 is inserted into the stamping and is headed on both sides to retain itself to the stamping. This variation can be less costly than the T-shaped wire and is suitable for certain applications. Alternatively, a portion of the base 76 may need to be removed to form shoulders on the contacts 72,74 similar to the shoulders on the contacts in the previous embodiments.

The elongated metal tapes of the present invention are used to make multiple rivet-type contacts. The tape is continuously fed into a cutter and the tape severed into multiple rivet-type contacts. The contacts are placed in a hole in a stamping and the body of the contact is deformed to secure the contact to the

stamping. The head of the contact can be shaped into the contour best suited for the application because of the inventive design of the tape and contact. The tape can be fed directly into a progressive die used to make the stamping. The tape is severed, inserted into the stamping, deformed and secured to the stamping all within the die.

While the preferred embodiments have been illustrated and described, numerous changes and modifications can be made without significantly departing from the spirit and scope of this invention. Therefore, the inventor intends that such changes and modifications are covered by the appended claims.