US2356662A - Apparatus for forming coils - Google Patents

Description

. Au 22, 1944. A

L. E. ENDSLEY APPARATUS FOR. FORMING COILS Filed June 18, 1945 zsneet-sheer lLllllr I III Il vrnlll l INV ENT OR. 4001.: E. ENDJLEY.

QTTOIQNEX Patented Aug. 22, 1944 APPARATUS son. FORMING ooILs Louis E. Endsley, Pittsburgh, Pa., assignor to The Frost Railway Supply 60., Detroit, Mich, a cor-- poration of Michigan Application June 18 1943, Serial No. 491,289

Claims. (01. 15364) While the present invention contemplates the forming of coils from bars or rods, for various purposes, it is particularly suitable for the making of helical springs, including the load carrying coils of friction springs such as those shown in my Patents 2,095,545, and 2,175,385. In the forming of helical springs, it is common practice to wrap the heated bar stock on a mandrel, to as accurate pitch as is possibleby present methods. Upon removal of the coil from the mandrel it is subjected to a further shaping operation in an eifort to give it the exact 'pitch desired. Thereafter it is often necessary to reheat the coil for quenching in oil or water.

Many springs are made by coiling them to a greater pitch than they will stand in service. After quenching and drawing they are subjected to one or many closures in a bulldozing machine until the desired'pitch' or the maximumpitch that the spring'will stand is produced. This method does not require any great accuracy in coiling the hot bar, it being only necessary that it be coiled to a greater pitch'than desired. Thus this bulldozing of the coil aftertempering, to completely compress the spring, allows a pitch finally that is equal to its maximum elasticity. This method finally produces-a spring of uniform pitch, but only'allows for a certain spacing'ofthe convolutions for a spring to any given strength of steel. My method insures that any spring made on a given mandrel will have adefinite pitch,

whereas by'the 'bulldozing method they simply arrive at a pitch which givesa certain strength or give back of the steel in the spring. I- can form any'spring' with one-half the convolution spacing or pitch that can be produced by the bulldozing process, because in that processthey are coiled'to ahigh pitch and then bulldozed down in an attempt toreduce them-to a desired pitch, or convolution spacing.

In making springs by the bulldozing method, the travel per convolution, which depends upon the-pitch of the spring with no load on it, is determ ned by the amount each convolution gives back when the spring is closed and released. One closing of theconvolutions by bulldozing may not overstrain the metal, in which case no equalization or adjustment of pitch would be obtained if the coil had'been wound to unequal pitch; thus the smallest pitch possible by the bulldozing method is limited to the strength of the steel.

In-my method, I can makeacoil of uniform pitchhalf the stress that the steel would have if there were the greater distances of the bulldozing method, between the convolutions.

In the use'of friction springs of the type having a single long coil and three shorter coils having cooperative frictional engagement therewith, it is desirable to have any creepage of the shorter end-coils be toward the ends of the spring, instead of toward the mid portion of the spring, for reasons explained in my Patent 2,175,385. In the present instance I control this creepage simply by varying thespacing of the convolutionsof the inner coil; that is, 1 make the spacing between the end convolutions greater than that at the middle of the spring. This causes the two end outer coils tocreeptoward the endsof the spring, thereby avoiding crowdingof the middle outer coil.

One object of my invention is to provide a means and method whereby helical springs can be accurately formed to any desired minimum or maximum distance between adjacent convoluti'ons. a l

Another object of my invention is to provide means whereby a coil can. be formed toaccurate pitch and diameter, by a simple winding operation which can be performed in so few seconds that the coil will still be sufliciently hot to enable it to be tempered without reheating.

Still. another object of. my invention-is to produce a friction. coil. spring'of such form that when a plurality of cooperating short coil sections are employed therewith themovements of the shorter coils onthe long coil will be socontrolled that the short coils sections will tend to creep towards the ends of the spring.

As shownin the accompanying drawings, Figure 1 is a side view of my apparatus, with a coil shown thereon in section; Fig. la is a reduced end view of th structure of Fig. 1; Fig. 2 is a side view of the central shaft of Fig. 1; Fig. 3 is a View taken on the line III'III of Fig. 2; Figs. 4, 5 and 6 are side, edgeand plan Views, respectively of one of the guides of Fig. 1; Fig. 7 is a plan view of the mandrel of Fig. 1; Fig. 8 is a side view thereof; Fig- 9 is an end View of the mandrel; Fig. 10 is a view of the mandrel with guides imposition therein; Fig. 11 is an end'view thereof, on an enlarged-scale, and Fig. 12 shows a completedspring which contains a coil as formed onthe mandrel.

The apparatus comprises a'base [2 that serves as a support for bearings l3. A tubular mandrel M has screw-threaded connection with a collar Pia formed on a tubular shaft I5 thatcarries a The mandrel and the motor 16 will be rotated as a unit when the pulley I! is being driven and the shaft 26 will rotate therewith, except when the motor is energized as hereinafter explained.

That part of the shaft 20 that lies within the body portion of the mandrel [4 has a series of camming surfaces 23 arrangedin two groups, the cams of one group being interspersed with the cams of the other group and disposed 180 there-' from or in diametrically opposite relation as shown more clearly in Figs. 2 and 3. Each of these cam surfaces 23 is contained within an opening 24 in a cam follower 25 that has a guide finger or lobe 26 that is angularly disposed relative to the follower 25, as shown more clearly in Figs. 6 and 10. These fingers may be of sufficient arcuate length to provide guiding surfaces along one-third or more of each convolution.

The mandrel H has a series of slots 21 and 28 open through the periphery of the mandrel at opposite sides thereof, to receive the followers 25. When the shaft is oscillated relative to the mandrel the followers will be shifted radially by the cams 23 to move their fingers 26 to projected and retracted positions relative to the peripheral surface of the mandrel.

The shaft 20, through its coaxially curved riblike areas I9, hasbearing engagement with the interior wall of the mandrel, on circular areas at l8a (Fig. 8) distributed throughout approximately the entire length of the mandrel.

These bearing areas l9 each may be made with considerably more than 90 bearing area on I9a, thus insuring maintenance of the shaft 26 centrally in the mandrel at all times.

v In the operation of forming a coil 30, an end of heated bar stock is brought into position between the mandrel and the pivotally mounted dog 3| that will clamp the end of the bar to the mandrel. ,The motor [6 is then energized to effect rotative movement of the shaft 20 and its cams 23 in the mandrel, so that the cam surfaces 23 will be brought into engagement with the cam surfaces 32 of the followers 25, to project the fingers 26 from the surface of the mandrel, to the position shown in Fig. 1. Energization of the motor to effect this rotative movement of the shaft 20 in the mandrel is effected from an electricalsupply line 33 provided with a reversing switch 34, through brushes 35 and collector rings 36 on the shaft 15. The portion 31 of the shaft 29 which lieswithin the motor can conveniently serve as the armature with which the brushes of the motor have engagement. The reversing switch 34 is used so that the motor [6 will turn the shaft in one direction at the start of a coilwinding operation and can then be reversed and the motor thus turn the shaft 20 in the opposite direction at the completion of the winding operation, in which case the cams 23'will engage the camming surfaces 38 on the follower 25, to retract the fingers 26 and thus permit the coil 30 to be slid from the mandrel. The winding operation-requires only a few seconds, and the coil when removed will still be hot enough to quench, thus avoiding the necessity of reheating as is required by those methods where there is further shaping or spacing of the convolutions after removal from a mandrel.

In assembling the parts in the mandrel, the followers 25 are inserted through the slots 21 and 28 and their openings 24 brought into axial alignment. Thereupon the shaft 20 is inserted, while so turned that its longest diameter (Fig. 3) is in alignment with the widest diameter of the follower openings 24 (Fig. 4). Thereafter oscillatory movement of the shaft will bring each cam surface 23 into engagement with the camming surfaces 32 and 38 of its associated follower, a1- ternately, toreciprocate the followers radially.

In order to insure that the motor will be positively stopped when the followers 25 reach their innermost and outermost positions, with no overrunning of the shaft after such positions have been reached, I provide an arm 29 (Fig. 1a) on the disc or washer 22 that is keyed to the shaft 29. This arm, at the end of about one-half revolution of the shaft in each direction, will engage one of the stop blocks 39 that are secured to the end of the motor IS. The motor may be of that design wherein continued supply of current after it has been stopped by the blocks 39 will not result in harm to the motor.

The mandrel I4 is tapered slightly toward its free end, to facilitate removal of the coil after the fingers 26 have been retracted below the peripheral surface of the mandrel. This taper usually need not be more than about A" in 10 of length, as is common. The mandrel provides a smooth cylindrical surface for engagement by the inner faces of the coil, along helical lines between the fingers 26, so that there is accuracy of coil diameter, the accuracy of pitch being insured by the fingers 26 as herein explained.

It will be seen that the guide fingers 26 are located on helical lines and that their coil engaging sides are similarly disposed, the spacing of the fingers axially of the mandrel being in accordance with the coil pitch desired. However, when making coils for frictional springs, I prefer to have the coil turns near the ends of the mandrel of slightly wider pitch than the intermediate turns, such pitch gradually increasing in the last one or two coil turns toward the adjacent extremities of the coil. This increased pitch may be a gradual increase of only .02 or .03 inch in each convolution.

By slightly increasing the pitch of the coil 30 from the innermost end of each coil 40 and 42, toward the adjacent end of the coil 30 in each instance, the outer ends of the coils 40-42 will not have as great tensional and frictional engagement with the coil 30 as their inner ends. Therefore any creeping tendency of the coils 40-42 will be toward the extremities of the coil 30 a distance limited by the usual stop shoulders 43, instead of crowding the middle coil 4| and perhaps expanding it so far in radial directions that it becomes overstrained and ineffective.

By making the long spring coil 3!! of smaller pitch or distance between convolutions than has been possible by the bulldozing method, compression of the spring with its convolutions solid" will not result in producing as high a stress in the steel, thus very materially prolonging its life. In the case of this frictional spring of Fig. 12, the end convolutions of coil 30 or those adjacent to the junctions of the three outer coils, are strained to a stress equal to that for full closing of-these 'convolutions,zlong before the other. .convolutions go so1id,- dueto-the friction of the-outer coilswith the inner coil holding the convolutions of the'inner coilapart near 'themiddle of each'outer coil, at partial closure ofthe -spring. It isdesirabl'e to have astress only aboutqne half 'or two-thirds of that which thesteel would stand if it was of the ordinary coil springwh'erein the .whole spring tool; the fsame stress without friction, so in my method I amable to coilsp'rings that. areplaced 11nder .very much lessstress in service, thus prolonging-their life.

I claim as my invention:

1. Coil-forming apparatus comprising a mandrel rotatable to wind a rod thereon, the mandrel being provided with a central bore and with radial openings that extend from the bore to the periphery of the mandrel, at points along a helical line, a cam shaft in the bore, and coilguiding members extending into the openings and radially movable in the bore, to and from projected positions relative to the peripheral surface of the mandrel, each of the said guiding members having radially-opposed camming surfaces between which eccentric surfaces on the cam shaft are so arranged that the coil-guiding members are reciprocated radially through rotative movements of the shaft relative to the mandrel.

2. Coil-forming apparatus comprising a mandrel rotatable to wind a rod thereon, the mandrel being provided with a central bore and with radial openings that extend from the bore to the periphery of the mandrel, at points along a helical line, a cam shaft in the bore, and coil-guiding members extending into the openings and radially movable in the bore, to and from projected positions relative to the peripheral surface of the mandrel, each of the said guiding members having radially-opposed camming surfaces between which eccentric surfaces on the cam shaft are so arranged that the coil-guiding members are reciprocated radially through rotative movements of the shaft relative to the mandrel, alternate guiding members extending in opposite directions and being radially moved in opposite directions upon each actuation of the shaft.

3. Coil-forming apparatus comprising a mandrel rotatable to wind a rod thereon, the mandrel being provided with a central bore and with radial openings that extend from the bore to the periphery of the mandrel, at points along a helical line, coil-guiding members movable in said openings, to and from projected position relative to the peripheral surface of the mandrel, a shaft for the mandrel, an electric motor carried by the said shaft, a cam shaft in the bore and engageable with the coil-guiding members, and means operable upon energization of the motor to effect rotative movement of the cam shaft relative to the mandrel.

4. Coil-forming apparatus comprising a mandrel rotatable to wind a rod thereon, the mandrel being provided with a central bore and with radial openings that extend from the bore to the periphery of the mandrel, at points along a helical line, coil-guiding members movable in said openings, to and from projected position relative to the peripheral surface of the mandrel, a shaft for the mandrel, an electric motor carried by the said shaft, a cam shaft in the bore and engageable with the coil-guiding members, means operable upon energization of the motor to effect rotative movement of the cam shaft relative to the mandrel, the motor being reversible, and means for positively .li'miting the distance which the cam shaft can be rotated in eitherdir'ecti'on. r l 3% 5.Coil forming apparatus comprising aiman dreli rotatable to 'wind a rod thereon, the mandrel being provided with a central bore and with radial openings that extend from the bore to the periphery of the mandrel, at points along a helical line, coil-guiding members movable in said open;

ings, to and from projected position relative to the peripheral surface of the mandreLa shaft for the mandrel, an electric motor carried by-the s'a-id shaft, a cam shaft inith bore an'd engageable with the coil-guiding members, means operable upon energization of the motor to effect rotative movement of the cam shaft relative to the mandrel, the motor being reversible, and means for positively limiting the cam shaft to not more than approximately rotative movement in either direction.

6. Coil-forming apparatus comprising a mandrel having a smooth, approximately cylindrical surface provided with radial openings, coil-guiding members extending into the openings and movable radially to and from projected position relative to the peripheral surface of the mandrel, and means in the mandrel, engageable with the inner portions of the guiding members, for reciprocating them radially, the projected outer portions of the guiding member having radial sides extending substantial distances alongside of and in approximate parallelism with helical lines along which bar stock will be Wound on the mandrel.

7. Coil-forming apparatus comprising a mandrel having a smooth, approximately cylindrical surface provided with radial openings, coil-guiding members extending into the opening and.

movable radially to and from projected position relative to the peripheral surface of the mandrel, and means in the mandrel, engageable with the inner portions of the guiding members for reciprocating them radially, the projected outer portions of the guiding members having radial sides extending substantial distances alongside of and in approximate parallelism with helical lines along which bar stock will be wound on the man drel, alternate guiding members extending radially in opposite directions and being radially moved in opposite directions upon each actuation of the reciprocating means.

8. Coil-forming apparatus comprising a mandrel having a central bore and provided with radial openings that extend from said bore to the periphery of the mandrel, at points along a helical line, radially-movable coil-guiding members in said openings and having inner body portions that are apertured in directions axially of the bore and having guide-finger portions projectible through the peripheral surface of the mandrel, and camming elements in the said bore and the apertures of the coil-guiding members, so arranged that upon rotative movements the said elements, relative to the mandrel, the guide elements will be reciprocated radially.

9. Coil-forming apparatus comprising a mancal line, radially-movable coil-guiding members 10 having inner body portions that are apertured in directions axially of the bore and having guidefinger portions projectible through the. periph eral surface of the mandrel, camming elements in the said bore and the apertures of the coilguiding members, so arranged that upon rotative movements the said elements, relative to the mandrel, the guide elements will be reciprocated radially, the said camming elements being formed on a shaft that has rotative movement in the bore, and means for positively limiting the distance which the shaft can be rotated in either direction. V v

' LOUIS E. ENDSLEY.

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