US2781817A - Device for bending contact springs - Google Patents

Device for bending contact springs Download PDF

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Publication number
US2781817A
US2781817A US320764A US32076452A US2781817A US 2781817 A US2781817 A US 2781817A US 320764 A US320764 A US 320764A US 32076452 A US32076452 A US 32076452A US 2781817 A US2781817 A US 2781817A
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United States
Prior art keywords
pressure
springs
spring
bending
lever
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Expired - Lifetime
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US320764A
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English (en)
Inventor
Tunberg Gustav Vilhelm
Jorgensen Anders Ossian
Parschin Alexander
Edman Ernst Erik Teodor
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Telefonaktiebolaget LM Ericsson AB
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Telefonaktiebolaget LM Ericsson AB
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D11/00—Bending not restricted to forms of material mentioned in only one of groups B21D5/00, B21D7/00, B21D9/00; Bending not provided for in groups B21D5/00 - B21D9/00; Twisting
    • B21D11/10—Bending specially adapted to produce specific articles, e.g. leaf springs
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H11/00—Apparatus or processes specially adapted for the manufacture of electric switches
    • H01H11/04—Apparatus or processes specially adapted for the manufacture of electric switches of switch contacts
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H49/00—Apparatus or processes specially adapted to the manufacture of relays or parts thereof

Definitions

  • the present invention relates to a device for bending springs, especially contact springs for such electromagnetic relays, as are used within telephony.
  • Different devices for bending contact springs have earlier been suggested, but none of them has given quite satisfactory results, an after-adjustment of the springs having proved necessary.
  • the object of the present invention is to avoid said drawback, the device being designed to effect the bending in dependence on the spring material.
  • the contact springs are bent through a press-operation with a pressure matched to the material properties and thickness of the separate springs in such a manner, that the contact springs have the same tension after bending when straightened out ,to a certain position, the working position.
  • Fig. 1 shows measured variations in the thickness of a blank of German silver, from which the contact springs are cut out.
  • Figs. 2 and 3 show a contact spring in unoperated and operated position, respectively.
  • Fig. 4 shows the extent of the required bending for three different spring-thicknesses in order'to give the same tension P in the position according to Fig. 5.
  • Fig. 6 is a diagram of the bending fas a function of the spring thickness t.
  • Fig. 7 shows a bending tool.
  • Figs. 8 and 9 ⁇ are diagrams of the spring thickness t and of the tension P, respectively, as a function ofthe pressure Q.
  • Fig. 1 shows measured variations in the thickness of a blank of German silver, from which the contact springs are cut out.
  • Figs. 2 and 3 show a contact spring in unoperated and operated position, respectively.
  • Fig. 4 shows the extent of the required bending for three different spring-thicknesses in order'to give
  • FIG. 10 is a principleillustration of a machine or device for bending springs according to the invention.
  • Figs. ll and 12 are perspective views showing the feeding of a continuous carrier and of loose contact springs, respectively, into' the machine in Fig. 10.
  • Fig. 13 illustrates a detail of a modiiied embodiment of the device shown in Fig. 10.
  • Such a lblank of German silver, out of which contact springs are cut, is, in the example shown' in Fig. 1, drawn in different scales for the three dimensions: length, width and height.
  • the length is 54m., the width 100 mm. and the height, i. e. the thickness, about 0.35 mm.
  • the maximal difference md is here 0.006 mm.
  • the corresponding measures of the thickness are 0.345 and 0.365 mm. respectively, 'the maximal difference md being 0.020 mm.
  • the formula may be simplified to spring, the thickness of which is 0.35 mm. Had the thickness ofthe spring instead been 0.40 or respectively 0.32 mm., it would have been necessary, to obtain the same tension P when straightening the spring according to Fig. 5, to make a smaller bending f for the thicker, and respectively a greater bending f for the thinner spring, as can be read from the given formula and is indicated with dotted lines in Fig. 4. This is directly apparent ⁇ on the curveillustrating the relation between the bending f in mm. and the spring thicknessj in mm. for a constant tension P, shown in Fig. 6.
  • So called point bending may be used when bending the springs.
  • the springs are thereby pressed in a bending tool, Fig. 7, between two tool halves 15, 116, the pressing surfaces of which are provided with varying or constant radius of curvature l along a greater or smaller part Y'of the eifective length of the spring.
  • the pressing surfaces of the bending tool are usually shaped so that the spring is nearly straight when in working position, Fig. 2.
  • the bending is concentrated to one or several points of the spring.
  • Such a spring can however not be straight when in working position. This is a drawback, since a greater distance between the springs in a group is then required.
  • the spring 7 are provided with a number of suitably distributed jags 17er ridges or embossed points which during the pressing operating penetrate into the spring material,l leaving small hollows.
  • the spring has a ⁇ curvature which, for springs made of the same material, depends on .the thickness of the spring and on the pressure. Equally thick springs are being given a greater curvature at. greater pressure. At the same pressure, for example when the pressing process takes place in a hydraulic press, the thick springs are being given a greater curvature than the thin ones. At use of an excenter press with constant play the pressure will be greater on the thick springs than on the thin ones, and the difference in curvature f, Fig. 4, and in tension P, Fig.
  • Fig. 9 shows the spring tension l in grams as a function of the pressure Q in tons for four dierent spring thicknesses t. If the radius of curvature R of the pressing surfaces of the bending tool according to Fig. 7 is changed, the position and the shape (characteristics) of the curves are also changed, see Fig. 8. By for example reducing the radius R, a greater tension is obtained at unchanged pressure and spring pressure.
  • the pressure Q between the tool halves 21, 22 is automatically regulated so, that springs with different thicknesses are given the same tension P, for example grams.
  • the pressure Q can be obtained by means of known devices per se.
  • the pressure Q is regulated by means of conical annular dished springs 33, 34, which operate a centrally located shaft having a pressure q. It is well known, as evidenced by the United States patents to Fawkes, No. 2,308,475 and Hay, No.
  • conical annular dished springs of the type shown can be designed so that the pressure q varies with the distance x of the shaft 35 from a lower position corresponding to the rest position kin such a manner that the resistance to an axial bend pressure with increased X- value first increases and thereafter decreases and finally increases again.
  • This is illustrated in the diagram shown in Fig. 10, where the pressure q of the shaft 35 is drawn as a function of the movement or distance x of the shaft from its lower position.
  • the useful pressure range is the decreasing or negative pressure characteristic shown as full line.
  • the upper half 21 of the used bending tool rests against a fixed stop 20.
  • the lower half 21 is movable.
  • the pressing device is now set in such a manner, that for all the occurring spring thicknesses it works with xvalues, which fall within an adjustment-area R on the curve of the diagram corresponding to the pressure q. Sincel a thick spring between the pressing halves 2,1, 22 corresponds to a greater x-value and consequently to a smaller pressure q within the area R than a thin spring does, it will accordingly be exposed to a smaller pressure Q than a thin spring would. The pressure Q on the springs fed into the pressing tool will thus vary with the thickness of the springs, and ⁇ be smaller for thick springs and greater for thin ones.
  • the additional pressure of the weight causes a pressure on the pressing half 22, which can be written
  • the characteristic of the last mentioned adjusting means causing a pressure may be changed in many different manners, as for examp (l)
  • the additional weight Aq may on one hand be pushed along its lever and on the other hand be changed with regard to its magnitude, the additional pressure knal, thereby being changed.
  • the spring housing may be displaced along the lever 28, the gear ratio b/a thereby being changed. Si multaneously with b/rz increasing or decreasing, the value of q for a certain change of the spring thickness t increases or decreases.
  • the cup-spring housing may be raised or lowered by means of screws 42, the working range of the springs thereby being displaced within the adjustment-area R of the spring characteristic.
  • Progressive springing may be obtained (not shown on the drawing). This is achieved by varying the number of working springs with the preceding pressing, The springs are thereby arranged so that part of them are not actuated until after a certain movement, either owing to their being without tension when they begin to work, or owing to their having a certain tension when they start working. In the latter case a jump in the spring characteristics will ensue. If a great number of springs are arranged to start working at different points, a relatively smooth curvature of the resulting characteristic can be obtained.
  • the cup-springs system 33, 34, 35 is, compared to the device in Fig. 10, replaced by a link and spring system 50, 51, 52, 53.
  • a link 51 is at one of its ends turnably cradled in a fixed point 50 and at its other end turnably connected with a link 52, which at its other end actuates the lever 28.
  • the junction point of the links is actuated by a normal draw spring 53 with linear characteristics.
  • the power characteristic of the system is a hyperbola curve. For increased x-value the pressure q decreases.
  • Fig. 11 shows such a feeding device.
  • the blank 60 forming the partly joined springs 91, 95 is moved over a roller 92 from the right to the left on the drawing in the direction of the arrows and comes either directly from the stamping machine or from a magazine.
  • the front or contact ends 91 of the springs are moved through the bending tool 61 62 and over a roller 90 on a driving shaft 63, driven by the same motor which drives the operating means for the tool according to Fig. l0.
  • the operating movement of the bending machine may also be effected by means of the press which stamps out the spring blank.
  • the blank is thereafter Wound on a magazine drum 64. In order that the bending tooll may be seen better, parts of three springs are removed in the drawing.
  • the bending of the springs proceeds in the following way.
  • the blank 60, Fig. 11, is moved forward, whereby 'one spring at a time with its end 91 centers between the two halves 61, 62 of the bending machine.
  • the two halves 61, 62 are pressed against each other at the moment a spring is placed between them. This is obtained by the regulating device shown in Fig. and with a higher pressure for a thin spring than for a thick one.
  • the two halves 61, 62 are separated as described in connection with Fig. 10 aand the next following spring is placed between them.
  • Fig. 12 shows a feeding device for loose springs.
  • An endless conveyor 66 with guiding pins 67 for the springs is guided by rollers 96 and 97 and is driven by a shaft 68 supporting roller 96.
  • Shaft 68 is driven by the motor also driving the tool according to Fig. 10. The upper half of the blank is driven from the right to the left on the drawing.
  • the springs 69 are applied onto the right part of the blank and led under a springy bar 70, in order to prevent them from loosening from the blank. Thereafter, the springs pass the bending tool 71, 72, the tool itself determining the position of the spring at bending.
  • the springs are ejected from the conveyor at its left side.
  • Other embodiments of the spring control may naturally be thought of.
  • the conveyor may for example be made to guide the front and rear ends of the springs, a recess for the bending tool being provided in the conveyor.
  • a condition for the spring to obtain the right bending is, that is is plane before bending, at least outside the bending range.
  • the front part is usually not plane.
  • planish the spring wholly or partially for example by point straightening.
  • the planishing may take place immediately before the bending in a series tool in connection with the point bending.
  • the bending of the spring should be carried out so as just to extend to the part of the spring intended for anchoring. That cart of the spring, which is planished, must exceed the bending range.
  • the pressing surfaces of the two tool halves should furthermore continuously move apart from each other outside the press-range, so that no bending of the spring at the edge of the press-range takes place.
  • One method consists of feeding the springs between tworolls having a suitable curvature and smooth or serrated surfaces. By regulating the pressure between the rolls the bending can be fitted so that the springs have a constant tension in working position. A higher roll-pressure is also required at rolling for a thin spring than for a thick one. Therefore, the adjustment may be achieved in the same manner as has been shown with regard to point bending in accordance with the example described with reference to the drawing.
  • a device for curving blank material in form of strips of various thicknesses for use as contact springs in electromagnetic devices comprising curving means including two coacting pressure members movable relative to each other for exerting a curving pressure upon a strip placed therebetween, and pressure regulating means for varying the pressure exerted by said pressure members so as, to decrease said pressure with increasing thickness of the strip material, said pressure regulating means including elastically deformable means having a pressure characteristic negative with increasing pressure, means responsive to the thickness of the strip material and coacting with said deformable means for applying a pressure to the latter increasing with increasing thickness of the strip material, and transmission means controlled by said deformable means and coacting with said pressure members to vary the pressure therebetween as a function of the pressure upon said deformable means.
  • a device wherein one of said pressure members is stationarily and the other movably mounted, the coacti'ng surfaces of said pressure members being curved in accordance with the desired curving of the strip material.
  • a device wherein the said coacting surfaces are formed with protrusions adapted to penetrate into the material of a strip placed between the two pressure members.
  • a device wherein one of said pressure members is stationary and the other movable, and wherein said transmission means comprise lever means connecting said movable pressure member with said pressure regulating means for transmitting the pressure varying effect of the latter to the movable pressure members.
  • the said elastically deformable means comprise at least one springy dished ring, mounting means peripherally supporting said ring, said lever means eifecting a deection of said ring corresponding to the spacing between the pressure members, the resulting loading of the ring causing said variation of the pressure exerted by said pressure members upon strip material placed therebetween such that the pressure exerted by said pressure members decreases with increasing thickness of the strip material.
  • said 7 lever means comprise a two-arm lever pivotal about a fulcrum, one arm of said lever engaging said movable pressure member, and wherein a rod disposed coaxially with said ring transmits a deection of the latter to the other lever arm and apivotal movement of said arm to the ring.
  • a device according to claim 6 and further comprising constant load means coupled with said lever so as to add a constant increment of pressure to the pressure transmitted by the lever to the movable pressure member by the elect of said springy ring.
  • a device wherein the said weight means is shiftably supported by said lever means for varying the magnitude of said transmitted increment of pressure.
  • said elastically deformable means comprise spring means including a plurality of superimposed springy dished rings, mounting means peripherally supporting said rings, the said superimposed discs being successively deflected for correspondingly varying the total loading of the spring means.
  • a device wherein one of said pressure members is stationary and the other movable, ⁇ and wherein the said self-setting control means comprise a pivotally mounted two-arm lever engaging with one arm the movable pressure member, linkage means including two pivotally connected elements, one of said elements being pivoted with its free end to a stationary point and the other being linked with its free end to the other arm of said lever for varying the relative position of the linkage elements upon pivoting of said lever, and loaded yieldable means having one end xedly mounted and the other connected to the pivot point linking the two elements of said linkage means for loading the link ⁇ age elements with a load controlled by the pivotal position of said lever.
  • a device according to claim 11, wherein the said yieldable means comprise a coil spring having a linear characteristic.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Springs (AREA)
  • Bending Of Plates, Rods, And Pipes (AREA)
US320764A 1951-11-28 1952-11-15 Device for bending contact springs Expired - Lifetime US2781817A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE722493X 1951-11-28

Publications (1)

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US2781817A true US2781817A (en) 1957-02-19

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Application Number Title Priority Date Filing Date
US320764A Expired - Lifetime US2781817A (en) 1951-11-28 1952-11-15 Device for bending contact springs

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US (1) US2781817A (en, 2012)
BE (1) BE515822A (en, 2012)
GB (1) GB722493A (en, 2012)
NL (1) NL88618C (en, 2012)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1139355B (de) * 1959-02-18 1962-11-08 Sonneville Roger P Verfahren zum Vereinheitlichen der betriebsmaessigen elastischen Durch-biegung von geschmiedeten Federklemmplatten fuer einen Schienenfuss
FR2439057A1 (fr) * 1978-10-16 1980-05-16 Sdg Sarl Machine automatique a usiner des rampes d'arrosage en une seule passe

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4403497A (en) * 1981-05-11 1983-09-13 Matteucci Felix V Bead bending tool
CN103990719B (zh) * 2014-05-30 2016-11-16 长城汽车股份有限公司 模具的斜楔结构

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US805508A (en) * 1905-02-25 1905-11-28 Carl Wellhoefer Sr Cask-head closure.
US1750471A (en) * 1929-03-28 1930-03-11 Alan C Hoover Machine for forming articles
US2162719A (en) * 1938-06-14 1939-06-20 Matilda K Hay Combination spring bellows control device
US2308475A (en) * 1941-08-07 1943-01-12 Crane Co Spring loaded stuffing box
US2490320A (en) * 1946-09-25 1949-12-06 First Ind Corp Method for adjusting spring mechanisms

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US805508A (en) * 1905-02-25 1905-11-28 Carl Wellhoefer Sr Cask-head closure.
US1750471A (en) * 1929-03-28 1930-03-11 Alan C Hoover Machine for forming articles
US2162719A (en) * 1938-06-14 1939-06-20 Matilda K Hay Combination spring bellows control device
US2308475A (en) * 1941-08-07 1943-01-12 Crane Co Spring loaded stuffing box
US2490320A (en) * 1946-09-25 1949-12-06 First Ind Corp Method for adjusting spring mechanisms

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1139355B (de) * 1959-02-18 1962-11-08 Sonneville Roger P Verfahren zum Vereinheitlichen der betriebsmaessigen elastischen Durch-biegung von geschmiedeten Federklemmplatten fuer einen Schienenfuss
FR2439057A1 (fr) * 1978-10-16 1980-05-16 Sdg Sarl Machine automatique a usiner des rampes d'arrosage en une seule passe

Also Published As

Publication number Publication date
GB722493A (en) 1955-01-26
BE515822A (en, 2012)
NL88618C (en, 2012)

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