DE2125609A1 - Spring contact as well as method for making the same. - Google Patents

Description

Dr A. MenUel

'Öl-Ing.VV.Dahlke May 21, 1971

Patent attorneys Da.-W / ho

137

IILINOIS TOOL WOBKS, Inc. Chicago, Illinois (V.St'.A.)

"IPederkontakt as well as process for the production of the same"

The invention relates to a spring contact and a method for producing the same. ^

In particular, the invention relates to a method for producing contact springs with multiple contact points for miniature potentiometers, where contact fingers are on a resistance surface are pressed and can be moved in relation to it

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one, electric. Make contact with it at the points where the contact fingers are in contact.

Contact springs for potentiometers have long been made from thin ones Sheets or strips made of thermosetting metal alloy, the contact being slotted to form a plurality of fingers, one full contact and one full System on the resistance surface is ensured. With miniature potentiometers the contact becomes very small and it is difficult to make him. to slit into the little finger width and also Slot widths to be provided without affecting the total width of the contact is decreased. Punching the slots in a device is inconvenient because the slots and fingers become too close together and because the tools are a very short one Have service life that have such narrow slots and contact fingers form. Narrow slots can be made with electron beam cutting However, this requires an extremely expensive machine, which must be operated under vacuum and which brings other production difficulties with it.

It has therefore been proposed to use contact springs with multiple fingers Manufacture small size by using small round or rectangular, square wires that are laid parallel to each other and are connected to one another at one end, their free ends forming the sequence of contact fingers. Such multiple wire contacts are in U.S. Patents 2,760,036 and

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• 5,328,707 shown. ...

The method used in the first-mentioned patent specification is there in columns 8 and 9 under the general heading? if t ¹¹ C. Manufacture of the wiper brush ^{11 is} described. The wire is wound onto a carbon rod and the entire wire spool is coated with copper. Then, the coated tape is removed from the rod, and the portion of the coating that has to remain in tact is coated with an acid-resistant material, and then the copper is removed from the core of the wire by nitric acid. Thereafter, the contact end is made and the contact is stored. This known method has several disadvantages, - inter alia that the contact wires are limited to platinum, because of the acid treatment, because of the fact that only one side of the wire winding can be coated, and because of the fact that the whole Circumference of the coil must be coated. This process is quite complicated, expensive, and time consuming.

In the other known method, the contact wire springs processed individually and placed individually in. brackets, in which they are welded and soldered. In view of the small size of the individual wiper wires, such processing is necessary extremely difficult and time consuming and not suitable for high productivity.

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According to the invention, the contact spring is made from a heat-resistant bar. Precious metal alloy wire produced, ■ which can only be attached to its fastening.gsen.de is coated so that multiple wire fingers remain free, which make contact with the resistance surface of the potentiometer heart. -to have. The wire is on a, massive one or protected mandrel wound up and covered so that the coating metal, for example silver, only in the distance lying strips is deposited, which extend in the longitudinal direction of the wire coil and on the outside of the Coil in the case of the massive. Dorns and on both sides of the Coil in the case of the protected mandrel. The cover is removed from the spool, and the spool is then in the mold a plate removed from the mandrel; which then in the transverse direction of the Wires in the middle sections of both the coated and also the uncoated. Strip is cut, resulting in long contact strip blanks with short wires attached to are bound at one end and free at the other end. The free Ends of the wires can then be formed into bent contact points (without having to cut off individual contacts) and then to develop. Hardness, "wear resistance and spring properties are warmebehan.deIt. If, the shaping and the heat treatment can be carried out on the contact strip blank, a. Part to be manufactured in. A 'form is delivered, the consumer side to the corresponding. If necessary is adapted further processed, for example by the strip is cut into individual contact widths, the

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man wants. In one pail as in the other, the individual contacts are formed on their coated parts, if you want them, and they are mounted on a carrier.

While the adhesion of the coated. Silver and the cohesive strength the silver deposit is normally sufficient for contact purposes, but when a greater strength is achieved should be, a sieve should be made after coating, by impact welding or resistance welding on the coated silver, by welding grass., by working, with one Electron beam or welded to the wire with a laser or by other welding and melting processes or is merged. ■ ■

The method according to the invention fills automatically. High performance process seamlessly «and is in its economic efficiency and in the performance of the contact spring produced think. There is no need to handle any part that is smaller than the finished contact and the contacts in any width from a normal contact strip can be attached. It is adaptable in creating the performance and dimensional requirements of the desired contact design. '

The invention is described below on the basis of an exemplary embodiment explained in more detail with reference to the drawings «In

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2125603

the drawings are:

Fig. 1 is a schematic representation in
. procedural steps for production
from. Contact springs for potentiometers according to the invention are shown,

Fig. 2 is a section through the contact in its arrangement in. a potentiometer and in its attachment a drag surface,

2a shows a detail in section on the line 2a-2a _; of Fig. 1 showing the coating deposited on the outside of the wire spool ...,., while the wire spool is being wound on a mandrel,

Fig. 3 is a diagram in which the manner is shown. is like a coating of both sides of the
Wire spool takes place,

Fig. 4 is a diagram of the wire band that is produced from the in.; ■ Ed. 3 is the coating step shown,

Fig. 5 is a detail in section on the line 5-5 of Fig. 3 and

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Fig. 6 is a diagram of another formed. Doms with a wire spool and a cover in front of the coating.

First, on the method of making a contact spring for a. Potentiometer according to the invention is referred to. As shown in Figures 1, 2 and 2a. Here, a bare wire coil 11 spirals in immediately successive. Contact on a senior. Tubular end orn. 12 wound, for example made of stainless steel. The wire can be of any desired size and composition, for example it can be a thermosetting alloy of 30 ^ gold, J> 0 % platinum and 2Q ^a / o silver, the remainder being copper and zinc. While the size of the wire will depend on the performance and dimensional requirements of the finished contact, an example in a miniature potentiometer would be a wire with a diameter of. 0.05 to 0.125 mm. The wire-wrapped tube is then immersed in a non-conductive rubber or plastic covering solution 13 to completely cover the tube and wire, and the resulting covering 21 is thoroughly dried and tapes 14 are removed along the length of the spool to remove the To leave circumferentially distributed bare bands 15 on the wire spool, on which a silver coating can be made.

The resulting strip, the coil and the mandrel, become one. Electroplating bath 16 brought, whereby.eine cylindrical anode 17 from

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Silver forms an enclosure that connects to the positive pole of a DC power source is connected. The negative connection of the direct current source is at 18 via the cover directly to the Tube 12 connected so that a. Contact through the tube with the wire winding. 11. is established. After that, silver is added to the Coil of wire in the strip. 19 deposited to any desired thickness, for example 0.05 to 0.125 mm as shown in Fig. 2a. ·

The coated wire winding and the tubular mandrel are then taken out of the bath 16 and the cover is removed by mechanical peeling. The wire spool is then in Cut open lengthways, for example in the middle of an uncoated one. Strip 2.3, and it is then removed from the mandrel removed, and straightened to form the plate 22, the has spaced strips of silver coating 19, between which strips of unbound wire lie. That ρ 'tape or plate 22 are then cut into strips by means of sections 24 through the middle of the untied strips 23 and, through Sections 25 through the middle of the coated strips 19 divided. This leads to a large number of individual contact strip blanks 26, the free unbonded wires on one edge and a tie coat 28 on the other. Have edge.

At this point one can go different ways, namely 'either to shape and heat treat the strip blank, while-

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rend he is in tact to form a production part., the consumer-side on lines. 29-along in. Individual contact widths, or the strip raw.lin.ge directly. the. Lines. 29 cut along to make individual contacts 3 ^ and 32 in. Of the desired. Width to form, and then to form the free ends, of the wires 23, and the heat treatment with the individual. Contacts to make. In. In one case, as in the other, the wire fingers are shaped in curved contact points in the forming tools. 33 and 34 indicated. This work should be carried out before the contact fingers are heat-treated in order to develop hardness, wear resistance and spring properties. " Any shape of the coated. Part of the contact can, if necessary, also take place after the heat treatment, because the silver prevents any springback that changes the shape. The finished contact can be spot welded at 36 to a carrier J5 as shown in FIG. 2, where the contact wires 2? curved loads. 38 have. That touch a resistance surface 39 of a potentiometer on a ceramic support 41 .. The spring fingers S? to grab. lower pressure on. the area 39. on. and are in a known manner by the. Carrier 35 can be moved over it »

lin modified method is ± n. Fig. 5 to 5 shown in which the wire winding and the cost files on both sides », coated are »Here is a cylindrical mandrel. "£> 1 provided., The one distributed around the circumference, extending in the longitudinal direction «"

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extending slots 52, and the mandrel 51, which in turn can consist of stainless steel, is immersed in the covering solution and dried on it before winding the wire spool. The width of the slots 52 after covering is the nominal width of the coated tape 53. A wire winding 54 is then wound around the cylindrical mandrel 51 and the covering solution is spread on the wire winding to cover only ψ the area of the bridges of the protected cylinder as shown at 55.

The covered coil and mandrel are then placed in a plating bath 16 which includes an outer cylindrical anode corresponding to the anode 17 in FIG. 1 and an axial silver rod anode 56. The anodes 17 and 56 are one along with the bispol DC power source connected, and the wire winding 54 itself is connected directly to the negative pole of the same power source. A coating then takes place on the outside of the wire winding between the cover strips 55 and on. the inside of the cover coil through the slots 56 to at 57 on the outside and at 58. to form a coating on the inside, as shown in FIG. The coatings 57 and 58 are made of silver and have a thickness on the order of 0.025 to 0.05 mm. ^;

After the coating, the cover is attached to the wire cradle .pulled off * and the bobbin is not loaded through the middle of a ©

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stratified wire strips cut, and from. the cylindrical. The mandrel removed, as shown in FIG. 4. Thereafter, the tape is unwound into a plate, as ^{shown at 1} 22 in Fig. 1, and the remaining operations are carried out exactly as described in connection with Fig. 1. The cover is under the - Wire winding 54 is provided with the protected mandrel 51 to form a resilient surface on which the wire is wound to prevent the coating on the wire from creeping up out of the slot area.

Another variation of the method is shown in FIG. Included the wire winding 61 is on a non-conductive tubular mandrel. 62 made of glass or the like. wrapped, and there is a cover with the help of strips 63 of masking tape attached to. the outside of the Winding in the longitudinal direction. Strip, glue, which are distributed around the circumference, around bare strips of wire. 64 to form between them, which are silver-plated in a bath as shown in FIG. In. this .. arrangement is the total coverage bypassed, as well as removing the cover from. the coil to the. Places where a coating should take place. The coil itself is connected to the negative pole of the direct current source connected, the anode 17 to "the positive pole, as in the case of the coating bath 16 was the case. After coating, the masking tape strips 65 are easily peeled off, and the tape is cut from the mandrel and unwound into the plate 22 and processed further, as has already been described.

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Claims (1)

Claims Spring contact, g e k e η η ζ e i c h η e t d u r c h a contact strip blank for spring contacts, consisting of a number of adjacent, relatively fine Wire fingers that are free on one En.de and on the other Ends are joined together in a continuous bound strip, the blank being a. Overall length has that is greater than the width of individual contacts, the free ends of the. Wire fingers are bent in such a way that bent Contact points are formed, and the wire fingers are heat treated so that they have spring characteristics are awarded. · '. "■ 2. Federkß.ontakt according to claim T, dadurc h. 'geke η η draws that the wire fingers are made of a: precious metal' P alloy, and a diameter of im. essential. 0.05 to 0.125 mm. . _: . . 3. spring contact 'according to claim. 1, thereby ge ke η η ζ ei ^ ch η et that. the bound strip is made by silver coating. ....-. . . - _A 4 · Method for producing a spring contact according to a of claims 1 to 3> characterized 209851/09 ?? - 15 - 2725609 M. e t that a single layer of wire spool is wound on a form, a non-conductive cover on the spool in addition to being laid on longitudinally extending bare strips thereof distributed around the circumference, a coating continuous strip of a metal of high conductivity is made on the bare strip of the coil, the cover is removed from the bobbin, the bobbin in Cut lengthways and of the shape in. The shape of a Plate is removed and the plate is cut along lines that halve both the coated and the uncoated strips, so that contact strip blanks formed from a number of adjacent. ! Wire fingers insist that on. are free at one end and at the other. End through the coating in. A continuous, bound strips, connected together, are. 5 * Method according to claim 4 »characterized in that the free. Ends, the wire finger to the Formation of bent contact parts are deformed .. β. Move »» .to Aaapruüh 4, thereby g e k e η. η ae i oh a e tj that the strip blank is heat treated becomes, 'such that de ». Brahtfingera! ”Eder characteristics -H- ?. Method according to claim 4, characterized in that g e k e η. η draws, that the free. Ends of the wire fingers are ornrfc to form curved contact points, and that the Fingers are heat treated so that they have spring characteristics be awarded. 8. The method according to claim 7, characterized geke n. N, fc ζ eic Ja η et that the strip enrohling is cut parallel to the wire fingers, into individual contacts' of the desired width. _; 9. Procedure according to. Claim 4, characterized e i c h η e t that the strip blank is parallel to the Wire fingers, to form individual contacts of the desired. Width cut up, is. 10. The method according to claim 9 * thereby geke nn ^ ζ e ⁷ I ch η et that the free. Ends of the wire fingers are deformed to form curved contact points on it. 11 ·. Method according to claim 9 »in that, g el en-nz e i G h n. e t that the one.2o.ne contact is heat-treated, such that the. Finger the wire. Assigned to each of the characteristics, that the coated part of the contact in. the desired Form is brought and that the coated for sale. is stored on a girder. ..- 15--2Ö98S1 / ÖÜ2? 2125603 12. Procedure according to. Claim 4-, characterized in that g e k e η η draws, that the mold is provided with through-slots is that the inside surface of the coil on it, expose that the cover on the outside of the coil only on the Bridge parts of the form is applied in such a way that "both Sides of the coil itself. extending in the longitudinal direction, strips distributed around the circumference are exposed, and that the coil is covered with a metal, high conductivity at both the Coated inside as well as on the outside of the sink is, such that continuous "coated strips, both are formed on the inside as well as on the outside of the coil, which extend in the longitudinal direction of the coil, and distributed on the circumference of the coil. 13. A method for producing a spring contact according to a of claims 1 "to 3f characterized in that that a coil is formed in a single layer of bare conductive wire, a coating on inner and outer sides of the coil in. The shape of continuous, itself longitudinally extending, more distributed on the circumference "coated strip of conductive metal is carried out through uncoated, longitudinally extending inner and outer strips of the coil are separated so that the coil is cut on lines which include both the "coated" and the "coated" also dde uncoated. Halve the strips so that Contact strip blanks are formed, which consist of a multitude of - 16 209851/0922 number of wire fingers lying next to each other are free on one Me and on the other En.de by one continuously coated. Strips on both sides of the Wire are connected, and in any order the free. Ends of the wire fingers to form curved contact parts. deformed on it and the strip parallel to the Wire fingers can be cut into individual contacts of the desired width. -. * 209851/0922 .Empty soap