JPS5814724B2 - Ittsutai Tekitafinga Contact Tosono Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to electrical contact members, particularly of the type used in variable resistance devices having movable contacts or wipers, such as potentiometers.

Much effort has been made in the past to provide satisfactory and inexpensive multi-finger contacts to serve as wiper members in these devices.

One such method of manufacturing a multi-finger contact includes winding a conductive wire around a mandrel, plating the wound wire with a conductive material, and having a plurality of fingers and a base portion. It involves selectively removing the plating to create some contacts.

This method necessarily involves several complicated and expensive steps.

A typical method of manufacturing inexpensive multi-finger contacts involves simply forming slots and removing material from a strip to create a plurality of finger members extending from a mutually spaced base.

This method would not provide the plurality of closely spaced thin fingers necessary to maximize the number of fingers to a given area that should receive contact.

Some efforts have also been made to shear adjacent fingers together.

This tends to cause the fingers to come into lateral contact with each other, thus limiting the ability of each finger to bend independently.

The present invention essentially utilizes a shearing method in which shearing of a portion of material from another portion is accomplished with a stroke large enough to stretch the sheared portion beyond its elastic limit.

As a result, each finger will include a small gap between adjacent side edges when returned to a coplanar position.

One embodiment of the invention is particularly adapted for use as a wiper in a rotary type potentiometer by utilizing the extension of adjacent finger sections.

In this embodiment, a series of arcuate shears are applied to a sheet of electrically conductive material.

Each adjacent shear step is to a depth that stretches the material beyond its elastic limit.

By returning the multiple sheared portions to a coplanar position, a crescent shaped gap will be provided between each adjacent edge due to the difference in length of each adjacent sheared portion.

Another embodiment of the invention, which also utilizes extension of each finger, is particularly adapted for use in series potentiometers.

In this embodiment, a plurality of straight fingers are sheared together, each finger being sheared downward to the point where it exceeds the elastic limit of the material so that at least a portion of the length of the finger is widened due to elongation. Each finger that becomes reduced in width will be independently bendable as a result of the reduction in width of each finger when returned to the coplanar position.

Accordingly, an important object of the present invention is to provide a multi-finger contact member made by a shearing operation, the fingers of which are independently bendable.

Another object of the invention is to simultaneously shear and stretch fingers from a sheet of material to provide a close arrangement of the fingers on a relatively small contact member and to allow independent bending of the fingers. .

Another object of the invention is to utilize a series of punch and die stations that contribute to reducing manufacturing costs.
It is an object of the present invention to provide a method for making relatively small integral multi-finger electrical contact members.

The present invention will now be described in more detail with reference to the accompanying drawings.

Integral multi-finger contact members, each finger operable independently, can be efficiently manufactured by the method of the present invention.

The method of the invention ensures this independent actuation by utilizing shearing action and stretching the thin strip of material beyond its elastic limit in each of the embodiments described below.

During the shearing step in the formation of each individual member, the finger members are moved out of the plane of the strip to a depth such that a particular portion will deform sufficiently beyond its elastic limit to not return to its original dimensions.

It will of course be understood that the actual depth of each shear stroke beyond the elastic limit of the material will depend on the length of the material to be deformed as well as the properties of the material itself.

Accordingly, the actual dimensions of the punch and die set utilized in the present invention will be apparent to those skilled in the art from the particular requirements of the contact member to be manufactured.

Examples of materials used in the above environment are brass or nickel-silver alloys.

It should be noted that these specific materials are merely exemplary and are not limiting of the materials that may be used in the present invention.

One embodiment of the invention utilizes differential elongation of adjacent finger portions to create a slight lateral gap between adjacent opposing side edges of the fingers.

The ends of the arcuate shear lines are not stretched, but the narrow portion of the material is stretched beyond the elastic limit of the material and removed from the plane of the strip.

When each finger portion is returned to the plane of the strip, the difference in length will appear as a crescent-shaped gap between adjacent fingers.

Yet another embodiment of the invention utilizes changes in the lateral dimensions of the narrow fingers as a result of elongation to ensure that adjacent fingers do not touch each other.

Referring to FIG. 1, it can be seen that a portion of the strip of conductive material will be sheared along arcuate shear lines.

The convex portion 14 of the shear line will be deformed from the plane of the strip.

The shear line 12 will be on one side of the imaginary line connecting the ends 11, and the portion of the sector strip outside the sector defining the sheared portion will be such that the section 14 is transversely When it is transformed, it will be clamped and held in place by the water.

FIG. 3 shows a punch and die set that would be used in accordance with the principles of the invention to shear arcs 14 from a strip 10 as shown in FIG.

The upper punch 30 has an arcuate shear edge that matches the desired shape of the shear line 12 and is associated with a lower spring loaded pressure receiver 36.

Lower die portion 34 is also associated with upper spring-loaded pressure receiver 32 .

The pressure receptors 34 and 32 serve to retain and clamp the concave side of the shear line 12 and the portion of the strip within the shear arc, as well as the portion of the strip 100 outside the shear arc.

As the upper portions 30, 32 are moved relative to the lower portions 34, 36, the punch 30 cuts the predetermined portion 14 from the body of the strip and moves the portion 14 downwardly to the predetermined maximum depth A.

This maximum depth A will be sufficient to stretch portion 14 beyond its elastic limit.

FIG. 2 shows the relationship between the body 10 on the inside or concave side of the shear line and the portion 14 on the outside or concave side of the shear line when the sheared portion 14 returns to be coplanar with the strip 10. The difference in length between adjacent edges is shown giving a crescent-shaped gap 18 between them.

A series of similar shear operations are further performed on the strip.

A subsequent shear is applied to the previously deformed portion 14, shown as a shear line 12a similar to the arc-shaped initial shear line 12.

However, at this stage the thin fingers 16 remain in the strip 10, while the portion 14a of the initially deformed portion 14 is sheared a distance B from the plane of the strip.

Since shearing of section 14 to the predetermined maximum limit depth A will stiffen section 14 to the extent that section 140 elasticity will change, distance B brings section 14a to its newly established elastic limit. It must be deep enough to extend beyond.

Distance B is shown to be larger than distance A, and for practical purposes will likely increase as the shear line increases in length, but distance B exceeds the newly defined elastic limit of portion 14a. It should be understood that sufficient amounts are required.

This subsequent shear strip will elongate portion 14a to a greater extent than the previously elongated portion, which is contained by finger 18.

In this second stage, arc-shaped bunch 30a cooperates with spring-loaded pressure receptor 36a, while die portion 34a cooperates with spring-loaded pressure receptor 32a in a manner somewhat similar to the description of the first shearing stage. .

After the predetermined number of shears have been performed to a depth determined by the depth required to stretch the part beyond its elastic limit, a contact member as shown in FIG. 5 is obtained.

A plurality of individual fingers 16 are formed, each slightly spaced from an adjacent finger by a crescent-shaped gap 18.

The gap thus allows for independent bending of the fingers 16 relative to each other, yet maintains very close alignment of the contact members along the predetermined short line of the contact.

The strip 10 may be further modified by providing punched portions 20.

The part of the body on the recessed side of the punching part 20 may later be modified according to the specific requirements of the installation or to provide a collector brushing member cooperating with the plurality of members 16 for specific use in a potentiometer environment. may be transformed into

The centralmost portion of the arcuate fingers 16 may also be further modified to provide a rounded tip 22 to localize the contact area of each individual finger.

With the above embodiment, arc fingers formed by punches having substantially the same arc shape will be somewhat narrowed in the middle of the ends.

The basic teachings of the present invention may also be utilized to manufacture integral multi-finger brushes in which the fingers are substantially straight.

FIG. 7 shows strip 39 modified using the principles of the present invention to provide a plurality of fingers 42 that converge along one end of base portion 40. FIG.

It is noted that each finger 42 is substantially out of lateral contact with each other and is separated from each other by a space 44.

Therefore, this shape allows each finger 42 to bend independently from each other.

FIG. 8 shows the punch and die station that would be utilized to provide the strip deformation as shown in FIG.

A punch 50 having a generally curved entry end is associated with a lower spring loaded pressure receiver 52 .

An upper spring loaded pressure receiver 56 cooperates with the lower stationary die member 54 to retain the strip at the end of the die finger formed therein.

As in the previous embodiments, the maximum depth of deformation of the portion 42 from the plane of the material is the depth that exceeds the elastic limit of the material.

The finger portion 42 will thus be elongated and the width will decrease toward the middle of the finger.

In FIG. 10, each finger 42 has a constriction or reduced width portion 46 and a wider portion 4 that merges with the strip material 39.
It can be seen that it has 8.

When the deformed fingers 42 are returned to a position coplanar with the strip, the reduction in width creates a sufficient gap between each adjacent finger to allow its individual independent bending.

The integral contact member 38 shown in FIG. 9 may be substantially modified by several of the aforementioned modifications to the strip.

The fingers may be cut along cutting lines a or b or intermediate positions thereof.

The cut along section line b in section 48 is shown in phantom in FIG. 9 and shows the close arrangement of the individual bend contact locations along the given line of contact.

Contacts made by cutting along cutting line b create fingers with narrowed portions 44 to facilitate twisting about their own longitudinal axis, and this capability may be advantageous in some circumstances. It should also be noted that

Cutting along cutting line a in the region of the reduced width portion 44 provides the most efficient use of material since the pair of members 38 is made from a set of elongated fingers 42.

Stretching and work hardening beyond the elastic limit of the material can serve to enhance the spring properties of the member.

Although the invention has been described with reference to specific embodiments, the invention is not limited to the embodiments shown in the drawings and described in detail herein.

[Brief explanation of drawings]

FIG. 1 is a plan view of a portion of the strip following a first shearing stage of operation. FIG. 2 is a plan view of the section of the strip of FIG. 1, with the first sheared section returned to a coplanar position and the second section of material
shows the shearing stage of. FIG. 3 is a partial cross-sectional view of the first station punch and die reset of the present invention, showing the punch at the bottom of its stroke. FIG. 4 is a partial cross-sectional view of the second punch and die station, showing the punch at the bottom of its stroke in a shearing operation following the stroke shown in FIG. FIG. 5 is a partial plan view of a multi-finger contact made in accordance with the present invention. 6 is an end view of the contact member shown in FIG. 5. FIG. FIG. 7 is a partial plan view of a strip of material deformed in accordance with another embodiment of the invention. FIG. 8 is a partial cross-sectional view of the punch and die set used to form the alternative embodiment shown in FIG. FIG. 9 is a perspective view of a multi-finger contact made in accordance with the embodiment shown in FIGS. 7 and 8. FIG. 10 is a partial plan view of an individual finger modified according to the alternative embodiment shown in FIG. 8; FIG. 10... Strip, 12... Arc shear line, 16... Finger portion, 18...
Crescent gap, 30...Top punch, 32
...Upper spring load pressure receiver, 34...T
Lower die part, 36...Lower spring load pressure receiver.

Claims (1)

Claims: 1. A one-piece electric wiper brush finger contact comprising: a base portion for attachment to a carrier;
a plurality of elongated, resilient arcuate contact fingers, each end of which joins integrally with the base, the contact fingers merging together in both joining areas with the base; , the side edges of adjacent arcuate fingers are separated by a crescent-shaped aperture over substantially their entire length, and the lateral edges of adjacent arcuate fingers are separated by a crescent-shaped aperture over substantially their entire length, and the lateral edges of adjacent arcuate fingers are separated by a crescent-shaped aperture locally in the finger and substantially on the finger. The finger contact is characterized in that a contact region is formed with a depression in the direction. 2. Shearing and stretching a plurality of adjacent sections along non-linear shear lines in a method of making a one-piece electric brush contact finger with a small gap between adjacent elongated fingers. , the majority of the shear lines are on one side with respect to an imaginary straight line connecting the ends of the sheared section, and the shearing and stretching steps are carried out in a direction transverse to the plane of the plate of conductive material. each adjacent section is stretched beyond its respective elastic limit in a constant lateral direction by a greater amount than the preceding section, returning each adjacent section to a common plane approximately in the plane of the plate, thus , the adjacent portions are slightly spaced apart from each other over a majority of their lengths, and the method further includes deforming a length of each elongated portion downwardly so that the ends of the sheared portion forming a contact point having a laterally aligned, small radius in the middle of the base portion, thus forming a plurality of closely arranged, independently deflecting contact fingers integrally in the base portion. .