US3329177A

US3329177A - Method and apparatus for making two-coil non-cumulative force spiral springs, and more particularly two-coil non-cumulative force spiral springs having a saddle between the coils

Info

Publication number: US3329177A
Application number: US424929A
Authority: US
Inventors: Jacob M Bishop; Dennis D Westbrook
Original assignee: Ametek Inc
Current assignee: Ametek Inc
Priority date: 1965-01-12
Filing date: 1965-01-12
Publication date: 1967-07-04
Anticipated expiration: 1984-07-04
Also published as: GB1120987A

Description

July 4. 1967 J. M. BISHOP AL METHOD AND APPARATUS FOR MAKING TWO- IL NON-CUMULATI FORCE MORE PARTICULARLY TWO-CO1 SPIR SPRINGS AND NO UM TIVE FORCE SPIRAL SPRINGS HAVING ETWEEN THE GOILS 3 Sheets-Sheet l SADDLE B Filed Jan. 12, 1965 F G. 2. u /2 ii "x% z 28 26 a| ao l8 n) u 24 22 I 20 FIG. 5.

F l G. 3.

INVENTORS JACOB M BISHOP 8:

BY DENNIS D. WESTBROOK OWMW ATTOR NE YS July 4, 1967 J. M. BISHOP ETAL 3,329,177 METHOD AND APPARATUS FOR MAKING TWO-COIL NON-CUMULATIVE FORCE SPIRAL SPRINGS AND MORE PARTICULARLY TWO-COIL NON-CUMULATIVE FORCE SPIRAL SPRINGS HAVING A SADDLE BETWEEN THE COILS Filed Jan. 12, 1965 3 Sheets-Sheet 2 F I G. 6.

F I G. 7.

44 34 48 40 O a2- 66A ass as g 17 7o 46 42 0 F I G. a. 7 74 72 INVENTORS 3 32 JACOB M. BISHOP Bu 1 I BY DENNIS D. WESTBROOK ATTORNEYS 7 7E 10 m w? E 3 L 3 H I AWG m m m w w m C H Y w m R L N N L LMO AI w P C Tw E E TLH R A T W R T IW O E P E Hmw T Sm w B A D R B M N 0 E MRAFL O ,E D .F S .V m IJS 1S A July 4, 1967 METHOD AND APPARATU SPIRAL SPRING NON-CUMULAT 5 Sheets-Sheet Filed Jan. 12, 1965 FIG. IO.

FIG. 9.

FIG. l2.

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K 0 m m I N wwm mm .D m N N GE AD J ATTORNEYS United States Patent 3,329,177 METHOD AND APPARATUS FOR MAKING TWO COIL NON CUMULATIVE FORCE SPIRAL SPRINGS, AND MORE PARTICU- LARLY TWO COIL NON CUMULATIVE FORCE SPIRAL SPRINGS HAVING A SAD- DLE BETWEEN THE COILS Jacob M. Bishop and Dennis D. Westbrook, Lansdale, Pa., assignors t0 Ametek, Inc., New York, N.Y., a corporation of Delaware Filed Jan. 12, 1965, Ser. No. 424,929 8 Claims. (Cl. 140-89) ABSTRACT OF THE DISCLOSURE The disclosure relates to forming a two-coil non-cumulative force spring having a saddle portion between the coils which are opposite hand. The spring is formed by a method involving moving an intermediate portion of a length of spring stock to draw the adjacent portions of the stock over forming edges to sharply bend each of the adjacent portions in order that it will tend to coil tightly. The adjacent portions are then straightened or reversely bent to further set them to coil tightly in the original direction but on a radius larger than the radius of initial set. The disclosed apparatus for carrying out the method involves a punch or the like for moving the said intermediate portion of the spring stock in a straight line past spaced forming edges and downwardly through an opening wherein the stock is straightened or reversely bent. Spring coiling chambers are provided to permit the coiling up of the saddle spring coils on retraction of the punch. A follower plunger is provided and the contour of the punch and follower plunger can be varied to vary the position of the saddle.

Non-cumulative force spiral springs are well known to the art being disclosed in, for example, Lermont Patent No. 2,609,192 and Foster Patent No. 2,609,191. Such springs are widely used commercially, being sold by the Hunter Spring Division of Ametek, Inc. 'under its trademark Negator. These springs are known to have a wide variety of uses including use as commutator brush springs in rotating electrical machinery. In the latter use, it has been known heretofore to employ a two-coil non-cumulative force spiral spring having a saddle between the coils for engagement of the brush when, in effect, the force of two non-cumulative force springs is desired. These springs are generally known as non-cumulative force saddle springs.

Non-cumulative force saddle springs have heretofore been made by first forming a single coil non-cumulative force spring by, for example, the method disclosed in Lermont Patent No. 3,007,239 which issued Nov. 7, 1961. The free outer end of the thus formed spring was then coiled until two equal coils were formed. The coils were then separated sufliciently to permit the formation of a fiat saddle portion employing a punch die. This method involves a large amount of time and handling and hence is very costly. Further, it makes the achievement of exact results difficult.

In accordance with this invention, .a new method and apparatus for forming non-cumulative force saddle springs is provided with a resultant simplification in the formation of such springs, greatly increased rate of production and decrease in cost, all with improved accuracy.

The invention and its objects will be further clarified on reading the following description in conjunction with the drawings, in which:

'ice

FIGURE 1 is a front elevation of a non-cumulative force saddle spring;

FIGURE 2 is a front elevation of a second non-cumulative force saddle spring;

FIGURE. 3 is a front elevation of a. third non-cumulative force saddle spring;

FIGURE 4 is a front elevation showing a saddle brush spring structure;

FIGURE 5 is a front elevation partially broken away showing an alternative saddle brush spring structure;

FIGURE 6 is a horizontal section through .apparatus in accordance with the invention;

FIGURE 7 is the horizontal section of FIGURE 6 showing spring stock being advanced;

FIGURE 8 is the horizontal section of FIGURE 6 showing the parts of the apparatus in different positions;

FIGURE 9 is the horizontal section of FIGURE 6 showing the parts of the apparatus in different positions;

FIGURE 10 is the horizontal section of FIGURE 6 showing the parts of the apparatus in still different positions;

FIGURE 11 is the horizontal section of FIGURE 6 showing the parts of the apparatus in still different positions; and

FIGURE 12 is the horizontal section of FIGURE 6 showing the par-ts of the apparatus in still different positions.

Referring now to FIGURE 1, a non-cumulative force saddle spring 2 has a straight section 4 of spring stock forming a saddle with the remainder of the spring stock being formed into tightly wound spiral coils 6 and 8. A second non-cumulative force saddle spring 3 is shown in FIGURE 2. Spring 3 has a straight saddle portion 5 and two tightly wound coils of spring stock 7 and 9. Spring 3 differs from spring 2 essentially only in that the straight saddle portion 5 is lower in relation to its coils. A third non-cumulative force saddle spring 18 is shown in FIG- URE 3. Spring 18 has a straight saddle portion 20 of spring stock being tightly coiled into

coils

22 and 24. Spring 18 differs from spring 3 in that straight saddle portion 20 is lower in relation to

coils

22 and 24 than is straight saddle portion 5 with respect to coils 7 and 9.

Referring now to FIGURE 4, saddle spring 2' is shown with coils 6 and 8 mounted on

rotatable spindles

10 and 12, respectively. Straight saddle portion 4 is shown in engagement with the top of a carbon brush 14.

Spindles

10 and 12 are mounted on the body 16.

Referring now to FIGURE 5, saddle spring 2 is shown with the straight saddle portion 4" in engagement with a carbon brush 26 within a cartridge 28. Coils 6" and 8" are in engagement with

shoulders

30 and 31 respectively of cartridge 28.

The above described springs and their application to commutator brushes are, as indicated previously, well known to the art. For example, see Welch Patent No. 2,695,968.

Referring now to FIGURE 6, spring forming apparatus 32 has

feed rollers

34 and 36 for advancing spring stock 38 from a supply not shown. Adjacent the

feed rollers

34 and 36 are

stock guide members

40 and 42. A cutter 44 cooperates with a pressure pad 46 backed up by a compression coil spring 48 to cut off spring stock 38.

A spring forming die 54 has an upper die member 56 with a horizontal opening 58 accommodating a punch 60 provided with a concave face 62. Die member 66 is spaced from die member 56 by a distance just sufiiciently greater than the thickness of the spring stock 38 to permit it to travel freely between die

members

56 and 66 and has an opening 68 for the accommodation of punch 60. Adjacent opening 68, die member 66 has a recessed portion 70 which extends through the bottom of die member 66 and isa gravity discharge opening for formed springs. Die mem- 3 her 66 has forming

edges

66A and 66B on either side of opening 68.

A plunger support member 72 is adjacent recessed portion 70 and has an opening 74 containing a plunger 76 which has a head 77 which is convex to match the concave face 62 of punch 60. Opening 74 is of a width just sufficient to permit free travel of punch 60 and stock 38. Plunger 76 is backed up by a compression coil spring 78.

A stop member 80 is positioned to limit the travel of spring stock 38 so that the amount of spring stock between cutter 44 and the center of punch 60 will equal the amount of spring stock between the center of punch 60 and stop 80. A gap guide 82 is adapted to move upwardly into

openings

58 and 68 to guide spring stock 38

past openings

58 and 68 and thence move downwardly out of the way of plunger 60. Gap guide 82 is desirable but not essential.

Operation Assuming the parts of the spring making apparatus 32 to be in the positions shown in FIGURE 6, spring stock 38 is fed by

rollers

34 and 36 through

stock guide members

40 and 42 and then through die

members

56 and 66 with gap guide 82 acting to guide the stock 38 as it passes

openings

58 and 68, as illustrated in FIGURE 7 The spring stock 38 is advanced until it contacts stop 80 at which point gap guide 82 is withdrawn and cutter 44 is urged against spring stock 38 which is backed up by pressure pad 46 and spring 48 to sever the spring stock 38, as shown in FIGURE 8.

Punch 60 is now advanced in opening 58 towards spring stock 38 and engages spring stock 38 to move a central portion 58A downwardly through opening 68 (FIGURE 9) and draw the remainder of the spring stock over forming

edges

66A and 66B, respectively, of die member 66 to sharply bend the spring stock on either side of portion 58A to effect an initial set of the spring stock so that the sections of spring stock on either side of portion 58A will tend to coil tightly on themselves in opposite directions, i.e. both outwardly. The portions of thus set stock are straightened by being moved downwardly through opening 68 which effects a reverse bending of the material which nevertheless still tends to coil into two coils, each coil coiling tightly on itself on a radius larger than the radius of initial set.

Punch 60 is advanced until portion 58A of the spring stock contacts plunger 76 which as the punch continues to advance is forced to move in opening 74 against the force of compression coil spring 78. The interaction of concave face 62 of punch 60 and convex head 77 of plunger 76 further reverse bends the spring stock at the juncture of the saddle portion 58A and the portions set for coiling to elevate the saddle portion 58A relative to the coils. Punch 60 continues to advance until all of the spring stock has entered opening 74 as shown in FIGURE 10.

Punch 60 is then withdrawn and is followed by plunger 76 urged by spring 78 which backs the spring stock out of opening 74 permitting the ends to coil as illustrated in FIGURE 11. When coils 58B and 580 have completely coiled as shown in FIGURE 12, the completed spring will drop downwardly clear of die member 66 through recessed portion 70.

The center saddle portion 58A of the completed spring ilustrated in FIGURE 1?. lies in a plane passing through the center of coils 58B and 58C. Variations in the position of the center saddle portion 58A can be achieved by varying the curvature of the punch 60 and the mating curvature of plunger 76. The smaller the radius of curvature, the higher the saddle portion will be relative to the coils. Thus, the springs shown in FIGURES 1 through 3 have saddles made by punches and plungers having progressively larger radii of curvature. It will also be apparent that variations in the set of the spring metal stock in being drawn around forming edges 66A and 6613 can lbe accomplished by varying the width of the punch, i.e. the distance the punch is from the forming edges.

Thus, the method of this invention comprises moving a portion of a length of spring stock intermediate the ends thereof to simultaneously draw the portions of stock adjacent the intermediate portion over forming edges to sharply bend to a predetermined radius the adjacent portions so that they each tend to coil tightly on themselves. The thus set adjacent portions are then reversely bent to set each adjacent portion so that it still tends to coil tightly on itself in the original direction of set, but on a radius larger than the radius of initial set. The adjacent portions are then allowed to coil up.

The specific apparatus and method illustrated in the drawings and described is merely by way of example and is not intended to be limiting.

What is claimed is:

1. The method of forming a two-coil non-cumulative force spring having a saddle portion between the coils of opposite hand comprising moving in a substantially straight line a portion of a length of spring stock intermediate the ends thereof to simultaneously draw the portions of stock adjacent the said intermediate portion over forming edges to sharply bend to a predetermined radius said adjacent portions so that they each tend to coil tightly on themselves and reverse bending the thus set adjacent portions to set each said adjacent portion so that it still tends to coil tightly on itself in the original direction of set but on a radius larger than the radius of initial set and all-owing each said adjacent portion to coil itself up.

2. The method in accordance with claim 1 in which the intermediate portion is urged upwardly after the first mentioned setting operation to further reverse bend the stock at the juncture of the adjacent portions and the intermediate portion.

3. The method of forming a two-coil non-cumulative force spring having :a saddle portion between the coils of opposite hand comprising moving in a substantially straight line a portion of a length of spring stock intermediate the ends thereof to simultaneously draw the portions of stock adjacent the said intermediate portions over forming edges to sharply bend to a predetermined radius said adjacent portions so that they each tend to coil tightly on themselves and straighten the thus set adjacent portions to set each said adjacent portion so that it still tends to coil tightly on itself in the original direction of set but on a radius larger than the radius of initial set and allowing each said adjacent portion to coil itself up.

4. The method in accordance with claim 3 in which the intermediate portion is urged upwardly after the first mentioned setting operation to further straighten the stock at the juncture of the adjacent portions and the intermediate portion.

5. Apparatus for forming a non-cumulative force spiral saddle spring having coils of opposite hand comprising means forming a narrow passage for a length of spring stock, an opening in said means on one side of said passage, an opening in said means on the other side of said passage opposite the first mentioned opening and providing forming edges, said means having a pair of opposite spring coiling chambers intermediate the ends of the second mentioned opening and extending in the direction of run of the passage for the spring stock, a punch mounted in the first mentioned opening to urge an intermediate portion of the spring stock into the last mentioned opening and draw the stock on either side of said portion over the forming edges to form a tightly wound spring coil on either side of the said intermediate portion of the stock.

6. Apparatus in accordance with claim 5 having means to feed spring stock into the passage and means to cut the spring stock to a predetermined length.

7. Apparatus in accordance with claim 5 in which the face of the punch which engages the spring stock is concave and in which there is included a backup plunger opposite the punch and having a convex face registering with the concave face of the punch and means to resiliently bias the backup plunger towards the punch.

8. Apparatus for forming a non-cumulative force spiral spring comprising die means having a narrow passage for a length of spring stock, an opening in the die means on one side of the passage, an opening in the die means on the other side of the passage opposite the first mentioned opening and providing forming edges, ea plunger support adjacent the die means and having an opening co-axial with the first mentioned opening, a punch mounted in the first mentioned opening to urge the intermediate portion of the length of spring stock through the second mentioned opening and into the third mentioned opening, a plunger mounted in the opening in the plunger support, and resilient means biasing the plunger towards the punch, said die means having a spring coiling gravity discharge chamber between the second and third mentioned openings to IeCBiVe the spring on the withdrawal of the punch, a punch mounted in the first mentioned opening to urge the intermediate portion of the cut-oh. length of spring stock through the second mentioned opening and into the third mentioned opening.

References Cited UNITED STATES PATENTS 443,256 12/1890 Logan 29-173 X 2,143,429 1/1939 Auble 72-351 X 2,223,321 11/1940 Kempe.

2,269,313 1/1942 Klocke 72351 X 2,348,871 5/1944 Wiley 18-19 2,602,411 7/ 1952 Schnell.

3,203,218 8/1965 Bolt et a1. 18-19 X WILLIAM J. STEPHENSON, Primary Examiner.

Claims

1. THE METHOD OF FORMING A TWO-COIL NON-CUMULATIVE FORCE SPRING HAVING A SADDLE PORTION BETWEEN THE COILS OF OPPOSITE HAND COMPRISING MOVING IN A SUBSTANTIALLY STRAIGHT LINE A PORTION OF A LENGTH OF SPRING STOCK INTERMEDIATE THE ENDS THEREOF TO SIMULTANEOUSLY DRAW THE PORTIONS OF STOCK ADJACENT THE SAID INTERMEDIATE PORTION OVER FORMING EDGES TO SHARPLY BEND TO A PREDETERMINED RADIUS SAID ADJACENT PORTIONS SO THAT THEY EACH TEND TO COIL TIGHTLY ON THEMSELVES AND REVERSE BENDING THE THUS SET