WO1999004404A1

WO1999004404A1 - Elongated metal tape for forming electrical contacts

Info

Publication number: WO1999004404A1
Application number: PCT/US1998/001263
Authority: WO
Inventors: Mitchell Zaleski
Original assignee: Pylon Tool Corporation
Priority date: 1997-07-17
Filing date: 1998-01-20
Publication date: 1999-01-28
Also published as: BR9811279A; AU6247698A; JP2001510927A; KR20010021946A

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.

Description

S P E C I F I C A T I O N

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.

Claims

WE CLAIM AS OUR INVENTION:

1. An elongated metal tape for use in making rivet-type

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 rivet-type 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

T-shape in cross-section.

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 rivet-type

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 rivet-type 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.