GB2082943A - Making relay contact spring - Google Patents

Abstract

To produce the contact on a relay contact spring, the contact spring is given an indentation (6), preferably at the same time as the contact spring is blanked from a carrier strip. Then the indentation receives a precious metal plating (7), by selective plating. <IMAGE>

Description

SPECIFICATION Relay contact spring This invention relates to relay contact springs and their manufacture.

The current method for applying precious metal contacts to relay contact springs is illustrated schematically in Fig. 1, which shows a plan view of a strip of contact springs, plus an edge-on view of the strip. In this strip, contact springs such as 1 are shown each extending between side strips 2, 3 provided with holes for assisting in feeding the strip. These are also thin metallic strips such as 4 interspersed with the contact spring strips. During manufacture the strip of contact springs is indexed to a contact welding position, at which a precious metal contact 5 is welded or rivetted on to the flat spring. The strip is then indexed on to the next station at which the contact spring is blanked from the strip.

The above method is relatively expensive of precious metal, which in view of the current prices of such metals is a serious disadvantage. An object of the invention is therefore to provide a method of manufacturing relay contact springs in which an economy in precious metal is attained.

According to the present invention there is provided a method of producing a precious metal contact on a relay contact spring, which includes forming a contact shape into the contact spring and thereafter applying a precious metal to the contact shape by selective plating.

According to the present invention there is further provided a method of making relay contact springs, which includes forming metal into an assembly including metal strips each to form one of the contact springs, together with supporting portions of the metal, forming an indentation on each said contact spring strip at the or each location thereof at which a contact is required, blanking each said contact spring from the assembly, and thereafter applying a precious metal to the or each said indentation by a selective plating process.

An embodiment of the invention will now be described with reference to Fig. 2, which illustrates how the novel method functions.

In the arrangement of Fig. 2, when the contact spring strip assembly is indexed to the contact forming station, a punch and die arrangement (not shown) functions to produce an indentation or dimple 6 in the contact spring at the required position. This production of the contact shape can be effected at the same time as the contact spring is blanked from the strip assembly.

After the spring has been blanked from the assembly a small region 7 of a precious metal is plated on to the indentation, preferably by the selective plating process described in our Application No. 7926126 (H. F. Sterling--M. P.

Drake-78-9). Thus only the immediate region which forms the contact is plated, which produces a useful saving in precious metal.

Note that if a contact spring needs twin contacts, as is often the case, the two indentations can be produced at the same time, and both plated at the same time.

In another practical application of our process, the metal strip is blanked to produce the contact springs, with each contact spring housing its dimple 6 produced at the same time as the blanking. However, the blanked and formed contact springs are retained in the continuous strip. This strip is now passed to a selective plating arrangement where the plating is applied to the region 7.

After the plating the strip is fed to a spring set assembly machine, where it is cropped into individual contacted springs which are then autoassembled into the spring set assemblies.

1. A method of producing a precious metal contact on a relay contact spring, which includes forming a contact shape into the contact spring and thereafter applying a precious metal to the contact shape by selective plating.

2. A method of making relay contact springs, which includes forming metal into an assembly including metal strips each to form one of the contact springs, together with supporting portions of the metal, forming an indentation on each said contact spring strip at the or each location thereof at which a contact is required, blanking each said contact spring from the assembly, and thereafter applying a precious metal to the or each said indentation by a selective plating process.

3. A method as claimed in claim 2, and in which the formation of said indentation or indentations on the said contact spring strip is effected at the same time as that contact spring strip is blanked from the assembly.

4. A method of making relay contact springs, which includes forming metal into an assembly including metal strips each to form one of the contact springs, together with supporting portions of the metal, the forming also producing an indentation at the or each location thereof at which a contact is required, applying a precious metal to the or each said indentations by a selective plating process, and thereafter separating the contacted contact springs from the supporting portions of the metal.

5. A method as claimed in claim 4, and in which the operation of forming said contact spring strips and the formation of the or each said indentation is effected as a single stage of the operations.

6. A method of making relay contact springs, substantially as described with reference to the accompanying Fig. 2.

7. A relay contact spring made by the method of any one of claims 1, 2, 3, 4, 5 or 6.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Relay contact spring This invention relates to relay contact springs and their manufacture. The current method for applying precious metal contacts to relay contact springs is illustrated schematically in Fig. 1, which shows a plan view of a strip of contact springs, plus an edge-on view of the strip. In this strip, contact springs such as 1 are shown each extending between side strips 2, 3 provided with holes for assisting in feeding the strip. These are also thin metallic strips such as 4 interspersed with the contact spring strips. During manufacture the strip of contact springs is indexed to a contact welding position, at which a precious metal contact 5 is welded or rivetted on to the flat spring. The strip is then indexed on to the next station at which the contact spring is blanked from the strip. The above method is relatively expensive of precious metal, which in view of the current prices of such metals is a serious disadvantage. An object of the invention is therefore to provide a method of manufacturing relay contact springs in which an economy in precious metal is attained. According to the present invention there is provided a method of producing a precious metal contact on a relay contact spring, which includes forming a contact shape into the contact spring and thereafter applying a precious metal to the contact shape by selective plating. According to the present invention there is further provided a method of making relay contact springs, which includes forming metal into an assembly including metal strips each to form one of the contact springs, together with supporting portions of the metal, forming an indentation on each said contact spring strip at the or each location thereof at which a contact is required, blanking each said contact spring from the assembly, and thereafter applying a precious metal to the or each said indentation by a selective plating process. An embodiment of the invention will now be described with reference to Fig. 2, which illustrates how the novel method functions. In the arrangement of Fig. 2, when the contact spring strip assembly is indexed to the contact forming station, a punch and die arrangement (not shown) functions to produce an indentation or dimple 6 in the contact spring at the required position. This production of the contact shape can be effected at the same time as the contact spring is blanked from the strip assembly. After the spring has been blanked from the assembly a small region 7 of a precious metal is plated on to the indentation, preferably by the selective plating process described in our Application No. 7926126 (H. F. Sterling--M. P. Drake-78-9). Thus only the immediate region which forms the contact is plated, which produces a useful saving in precious metal. Note that if a contact spring needs twin contacts, as is often the case, the two indentations can be produced at the same time, and both plated at the same time. In another practical application of our process, the metal strip is blanked to produce the contact springs, with each contact spring housing its dimple 6 produced at the same time as the blanking. However, the blanked and formed contact springs are retained in the continuous strip. This strip is now passed to a selective plating arrangement where the plating is applied to the region 7. After the plating the strip is fed to a spring set assembly machine, where it is cropped into individual contacted springs which are then autoassembled into the spring set assemblies. CLAIMS

1. A method of producing a precious metal contact on a relay contact spring, which includes forming a contact shape into the contact spring and thereafter applying a precious metal to the contact shape by selective plating.

2. A method of making relay contact springs, which includes forming metal into an assembly including metal strips each to form one of the contact springs, together with supporting portions of the metal, forming an indentation on each said contact spring strip at the or each location thereof at which a contact is required, blanking each said contact spring from the assembly, and thereafter applying a precious metal to the or each said indentation by a selective plating process.

3. A method as claimed in claim 2, and in which the formation of said indentation or indentations on the said contact spring strip is effected at the same time as that contact spring strip is blanked from the assembly.

4. A method of making relay contact springs, which includes forming metal into an assembly including metal strips each to form one of the contact springs, together with supporting portions of the metal, the forming also producing an indentation at the or each location thereof at which a contact is required, applying a precious metal to the or each said indentations by a selective plating process, and thereafter separating the contacted contact springs from the supporting portions of the metal.

5. A method as claimed in claim 4, and in which the operation of forming said contact spring strips and the formation of the or each said indentation is effected as a single stage of the operations.

6. A method of making relay contact springs, substantially as described with reference to the accompanying Fig. 2.

7. A relay contact spring made by the method of any one of claims 1, 2, 3, 4, 5 or 6.

8. A relay contact spring formed by a strip of a springy metal on which an indentation is produced at the or each locations of the contact spring at which a contact is required, the or each said indentation having a precious metal applied to it by a selective plating process.