US2831103A - Torsion spring making machine - Google Patents

Description

April 15, 1 w. CONRAD TORSION SPRING MAKING MACHINE 2 Sheets-Sheet 1 Filed Jan. 50, 1956 Ulko INVENTOR.

wilbum Conron cl CQM ATTORNEY April 15, 1958 w. CONRAD TORSION SPRING MAKING MACHINE 2 Sheets-Sheet 2 Filed Jan. 30, 1956 Patented Apr. 15, 1958 United States PatentOfiice TORSIUN SI'RENG MAKING MACHINE Wilbur Conrad, Unionville, Conn. I Application January 30, 1956, Serial No. 562,273

7 Claims. (Cl. 219-153) This invention relates to mechanism for coiling wire and relieving stress therein, and more particularly to the release of coiling stress during the production of torsion springs of both a helical and a spiral configuration.

A torsion spring is one which may have itsfree end twisted about a longitudinal axis relative to a fixed end and which will tend to return in an untwisting action to a state of rest. A torsion spring may be made on a machine of the type shown in the U. S. patent to Blount and Fisher Serial No. 2,163,0l9 of June 20, 1939, in which awire has one end secured to a reciprocable a'nd rotatable coiling arbor and is drawn forward into a helical or a spiral shape by rotation of the arbor. The springs as thus manufactured have a residual stressed condition in the grain structure of the wire as produced by the coiling operation as well as prior col-d working procedure. The conventional method ofrelieving such stress by heat treatingthe springs in a basket introduced into a furnace has involved difficulties, owing to the fact that the loosely positioned springs tend to move in the general direction of their coiled wire while being heat treated, so that they become entangled and not readily separated. In addition, such heattreatment may be quite uneven.

A spiral may be coiled if the arbor is held axially stationary. However, spiral springs have had to be coiled by a hand controlled operation of the machine, since the conventional methods have not given a uniform spacing between the coils. That is, the wire in the first convolution is stressed beyond its elastic limit in being coiled about an arbor of small diameter and so will not recoil materially. As the coil grows in diameter, the coiling stress decreases progressively and the tendency to recoil increases so that the separation of the convolutions after recoiling becomes increasingly greater with the radial distance. Yet, many objects require an even spacing.

One type of procedure has involved feeding a paper spacer between the coil convolutions as coiling proceeds. When the coiling has been completed and the wire is still tightly confined around the arbor, a steel ring or cup is placed over the spring and the latter is allowed to recoil slightly or enough for removal of the spring from the arbor. Then, the spring, while confined in the cup, is heat treated. In the manufacture of hair springs, used in spring wound clocks and watches, it is impractical to use a paper spacer on the very small sized material used. Hence, it has been customary to coil the springs, four at a time, by cuttingfour lengths of wire and hooking the four wires into slots in the arbor in such a manner that the Wires are coiled one on top of the other. Thus, each spring has three thicknesses of wire between each of its convolutions. It has been found that after the springs have been removed in the confining cup and heat treated, the four springs will have slightly different diameters, so that it is often necessary to discard the first spring as being too small in both internal and outside diameters and the last spring as too large. Thus, only the inner one or two of the springs may be usable for the required purposes. Many types of coils require a uniform spacing. For example, acigarette lighter resistance element would become short circuited if any of its convolutions were in contact.

In accordance with the disclosure in my prior copending application Serial No. 546,142, filed November 10, 1955, I have provided a construction in which electricity is introduced into a wire coil while it is being progressivelymade on a universal spring coiling machine, and reference is to be had thereto for an explanationof the theory and practice involved.

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The primary object of this invention is to provide a wire coiling machine adapted primarily for making torsion springs, both helical and spiral, in which electricity is introduced into the wire while it is being coiled under torsion.

Another object is to provide a machine of this type in which the rate of wire feed varies during the coiling action, but the amperage per unit length of the wire being coiled is controlled.

Another object, in the manufacture. of a spiral coil, is to increase the current input as the coil diameter increases sons to control the spacing of the coil convolutions after recoil.

A further object is to provide a machine of this type in which wire is being forcibly twisted around a nonreciprocating rotating spindle in the production of a spiral spring, and. electricity is introduced into the coil as it progressively increases in size, and in which the amperage of the current is varied both according to therate of wire movement and as required to provide an increasingly greater annealing effect in the Wire as the coil diameter grows. Other objects will be apparent in the following disclosure.

Referring to the drawings illustrating manufacturing machine of the Blountpatent:

Fig. 1 is a somewhat diagrammatic plan view of a portion of the machine adapted for the coiling and electrical treatment of a wire; j

Pig. 2 is a fragmentary vertical elevation of the same;

Fig. 3 is an enlarged fragmentary detail of the coiling arbor in association with the wire cutting mechanism and illustrating diagrammatically the electriccircuits and cam controls therefor which will serve for varying the current introduced to the wire being coiled; and v Fig. 4- is a fragmentary view of a reciprocable arbor and associated parts arranged for coiling a helical spring.

Referring first to the general construction of a coiling machine described in said Blount et al. patent and illustrated in Figs. 1 and 2 herein, an arbor 10 is rotated intermittently by means of a long gear 11 fixed relative to the arbor and which is in turn driven by a larger diameter gear 12, these parts being so mounted that the arbor 10 may be reciprocated axially during rotation for making a helical coil or be held stationary for making a spiral coil. The driving gear 12 may be rotated by a pinion 13 fixed to the shaft 14 carrying the driving gear and which is in turn rotated by a reciprocable rack bar 15. The rack bar is driven by a pitman rod 16 having an adjustable connection with a main driving gear 13 which is in turn rotated by a power driven pinion 19, all of which is more fully described in said patent.

The long gear 11 and its associated arbor 10 may be held axially stationary for winding a spiral, or the arbor a torsion spring general type shown in said may be reciprocated by means of the rocking lever 20 pivotally mounted at 21 on a suitable portion of the framework. This lever has a fork 22 at its outer end which rides between spaced. flanges of a collar 23 positioned between nuts 24 onthe upper end 25 of the arbor. The latter rotates within the collar.

projecting from the collar and so arranged that rocking 3 of the lever 20 will serve through that pin to reciprocate the arbor 10.

A portion of the stationary housing 28 below the driving gear 12 carries a U-shaped bearing member 29 which provides for locating the reciprocable gear 11 in a definite axial position and resists the lateral thrust involved in forcibly drawing wire forward and coiling it on the arbor 10. j The spindle 14 drives the arbor in one direction through a pawl and ratchet comprising the ratchet wheel-32keyed to the spindle. The plate is stopped in a definite driving position by means of the locking or stop finger 34 cooperating with stops rotated by the plate 32. The finger is suitably moved by a cam control. These various parts may be made as more fully described in said patent. i The reciprocation of the arbor is controlled by cam 'bars 40 and 41 adjustably positioned on a carrier 42 which is pivotally adjusted .on the frame. The cam bars are fixed relative to a roller or cam follower 43 mounted on the lower end of the slide 44 suitably supported in vertical standards 45. The upper end of the slide 44 is pivotally connected to rock the lever 20 which in turn serves to reciprocate the arbor 10. The cam bar carrier 42 is adjustably mounted to reciprocate with the rack bar 15, so that if the cam bars are tilted, their movement toward the left will draw down on the slide and move the arbor 10 upwardly. When the driving gear 18 makes its return stroke, the lower cam bar 41 will return the cam'roller 43 to its lowermost position and at the same time provide a dwell period during which the wire may be fed to the arbor. In the arrangement illustrated, the machine will coila torsion spring of spiral shape. That is, the cam bars 40 and 41 are arranged horizontally and parallel, so that the spindle 10 will be held immovable axially while it is being rotated by the driving gears 11 and 12. Hence, the wire will be coiled in the from of a spiral, such as is required for clock springs, cigarette lighters, and other uses.

A slot 50 in the arbor (Fig. 3) is so arranged that the free end of a wire 52 may be fed into the slot and held there as the arbor starts rotating, so that thereafter the wire is drawn forward and coiled about the arbor as a spiral. A pin eccentric to the arbor is usually employed for making a helix. The wire 52 is suitably fed forward to the slot by driving rollers 54 and 55 (Fig. 1) which are power driven and cam pressed into engagement with the wire. Thereafter, the driving rolls are separated by spring means so as to leave the wire free for being drawn forward solely by the rotating arbor. The lower driving roll 55 is driven through a small pinion 56 which meshes with a rack bar 57 reciprocated by a cam 58 on the main drive shaft 59. These parts may be constructed and operated as shown in the patent application of Halvorsen, Serial #446,433, filed July 29, 1954, which matured to Patent No. 2,792,869 on May 21, 1957. The construction is such that the driving rolls are driven intermittently and then they are released from driving engagement with the wire 52 so that the wire is pulled forward and coiled solely by the rotating arbor 10.

After the wire has been fed to the arbor and drawn forward into a tightly wound coil, it is then severed by means of a reciprocable knife 60 (Figs. 1 and 3) mounted on a slide 61 and moved across the end plain face of a cylindrical cut-off tube 64 suitably mounted on the framework of the machine and through which the wire 52 is drawn forward by the arbor. The knife 60 is reciprocated as described in said Blount et al. patent by means of a cam 65 (Fig. 1) mounted on the camshaft 66 which is driven through bevelled gears 67 by the main drive shaft 59. The various cams are coordinated to provide the necessary sequence of operations.

A primary feature of this invention involves introduc- 1ng an electric current into the wire to condition it for coiling. Accordingly, I pass an electric current, and preferably a low voltage alternating current, through the 4 wire while it is being coiled. The current may be introduced progressively to the portion of the moving wire immediately in advance of the coiling zone, as shown, so as to condition the wire for the torsion stress applied thereto. I have found that an alternating current causes a controlled molecular orientationor other electrical effect, as well as heats the wire and so reduces the wire drawing and coiling stresses and produces a greater uniformity of grain structure, so that the coil will ultimately recoil to a predetermined and controlled extent. This electrical treatment is maintained while the wire is brought under the torsion stress and before it has been severed from the incoming wire, so that the stresses are relieved while the shape of the coil is substantially maintained.

In the embodiment illustrated in Fig. 3, one terminal of the electric circuit is connected to the arbor and the other terminal to a portion of the framework contacting a straight stretch of wire traveling to the arbor. This is shown as comprising a binding post 70 forming one terminal of the electric circuit which is attached to the cutoff tube 64 with which the wire slidably contacts in its passage directly therefrom to the coiling arbor. The other terminal connects to the arbor, and this is preferably accomplished by means of a suitably mounted spring finger 72 which makes a sliding contact with the cylindrical surface of a metal body 73 in which the arbor 10 is axially secured as by a set screw. This arbor supporting body 73 is insulated from the machine by means of a fibre bushing 74 (Fig. 3) having a cup shaped lower end in which the cylinder 73 is secured, as by means of a set screw 75. The upper portion 76 of the bushing is frustoconical in shape and is drawn upwardly into a correspondingly shaped socket in the elongated gear 11 by means of a draw bolt 77 threaded into the top of the fibre bushing. This draw bolt 77, which passes axially through the rotatable spindle 25, is suitably adjusted in position by means of set nuts 78 at the top of the spindle. The brass spring finger 72 which slides against the outer metal surface of the block 73 is suitably mounted on an insulated bracket (not shown) carried by the framework of the machine.

The alternating electric current of suitable origin is preferably derived from a stepless variable voltage transformer, such as a Variac transformer 80 (Fig. 3), connected to a power line 81, and the voltage is con trolled to provide a predetermined current flow, depending upon the size and resistance of the wire, which will relieve the stresses without overheating the wire. The Variac stepdown variable voltage transformer 80 comprises a transformer winding on a laminated ring core of magnetic metal. The A. C. power line 81 of suitable voltage, such as 110 volts, is connected to the ends or suitably spaced terminals of the coil. One side of the power line and a transformer terminal is connected to the load and the other line from the load is connectedto a movable arm 84 which makes a sliding contact with the transformer coil. In the illustrated showing, a supplemental step-down transformer 85 is interposed between the ultimate load and the Variac transformer. The primary coil of this secondary transformer constitutes the load for the Variac, and its secondary coil is directly connected to the terminals 70 and 72 and thus serves to transmit a low voltage alternating current to the wire being coiled. This auto-transformer involves the induction of a counter EMF which materially limits the no-load current flow, and the voltage that is derived therefrom is determined by the ratio of the number of transformer turns picked off by the movable arm to the total number of turns in the transformer. Thus the current flow is limited primarily by the load resistance of the wire. It will also be appreciated that the low resistance of the wire for the ordinary sizes of wire coils requires a very low voltage input for giving the desired heating and electrical effect.

In orderto control the make and break of the circuit and thus introduce the current to the wire for the required time period, I may employ a magnetic starter of suitable construction by which a low voltage current is made and broken by a cam operated switch, and this in turn serves through a magnetic relay to control the make and break of the circuit of the step-down variable voltage transformer. As illustrated, a normally open switch 88 of suitable construction controls the flow of the 110 volt current to the step-down transformer 80.

To make and break this circuit in timed relation with the coiling operation, the main camshaft 66 (Figs. 1 and 3) has a cam 89 fixed thereon having high and low surfaces so arranged as to swing a cam follower arm 90 of the normally open switch S8 and close the circuit either before or preferably after a single turn or more of the wire has been wound on the arbor.

A second cam 92 on the camshaft 66' is specially shaped to move the contact arm of the variable voltage transformer by a suitable mechanical connection, such as a large gear 93 mounted on the framework which drives a smaller gear 94 (Fig. 3) axially mounted on the transformer and connected to swing the arm 84 and thus vary the voltage as needed.

The cam 92 has a high portion shaped to give the required motion to the cam follower'arm 95 which is keyed to and turns the shaft ofthe gear 93.

This serves to vary the voltage or the current input to the wire for the following purposes:

(1) The rate of wire feed may be varied because the rotation of the arbor is effected through a crank motion as illustrated, in which the rate of rotation varies from zero to a maximum and then down to zero. Accordingly, the Variac control arm may be moved to increase the current flow from a minimum requirement at the start of the arbor rotation to a maximum correlated with the maximum speed of wire movement and then again diminished toward the minimum. This applies to the treatment of both a spiral and a helical coil made on a machine having a variable rotative speed for the arbor. Hence, if a helical coil is being made on this machine or on that of my said prior application, in which the cams 41 and 42' are adjusted to an angular relationship so as to cause reciprocation of the arbor in one axial direction or the other during the coiling, the transformer output will be varied to insure a substantially uniform current flow per unit rate of wire movement so that the temperature of the moving wire will be held substantially uniform whatever may be its rate of movement.

(2) Another requirement is related to the fact that as a spiral coil increases in diameter, the coiling stress imposed by the coiling operation on the wire gradually decreases below the elasticity limit, so that when ulti' mately released and permitted to recoil, the spring will have increasingly greater spacings between the convolutions radially outwardly from the center. It is therefore desirable to so treat the wire electrically that it is annealed or otherwise affected to relieve the residual stress in the wire and permit it to assume, in recoiling, substantially a uniform spacing of convolutions. During the first stage of winding the wire on the arbor, the coil will be wound tightly around a small arbor with a stress above the eiastic limit of the wire and so will remain in substantially the coiled condition imposed by the winding operation. dence, the current requirement at the beginning of the coiling is a minimum, and the cam controls may be such as to turn on the current or to provide only a minimum heating and other electrical effect only after that point has been reached at which the elastic limit of the wire is no longer exceeded by the coiling stress. ence the requirement from this viewpoint is that of gradually increasing the current flow per unit resistance as the spiral coil grows larger in size. This treats the wire with a current input which in- 6 creases progressively so that the wire entering the coiling zone has its temperature increasingly higher or its annealed condition greater as the coil grows in diameter.

Thus, if a wire were wound on this machine by standard procedure, it would vultimately recoil from its initial tightly wound condition to an increasingly greater spacing of convolutions outwardly of the center. But, when treated with electric current in accordance with this invention, a unit length of the wire comprised in the portion being heated is preconditioned just prior to and during the coiling stage so that enough of the residual stress within the wire is relieved by the pro-annealing step so that when the coil is removed from the machine, it will have a required substantially uniform spacing of convolutions. In the machine as illustrated, the major heating and electrical effect on the wire takes place largely on the straight length of wire between the coil and the cutting off tube and at the beginning of coiling so that when the moving wire starts its wind around the previously made convolutions, the residual wire drawing stress has already been relieved and the wire is in such a condition that its elasticity limit is below the stress imposed by the coiling. Hence, the wire retains substantially the convolution shape imposed by the coiling operation.

The cam 92 may be shaped to give a uniformly increasing current flow when a spiral coil is being wound, so that the unit length of the wire portion being coiled will be progressively heated to a higher temperature and the electrical effect increased as the coil diameter increases, whereby the ultimate annealing effect will be substantially uniform through the unit increments of length of the wire. Likewise, when a helical coil is being made, as indicated in Fig. 4, on a machine of the general type shown in said Blount et al. patent, the rate of coiling is varied by the pitman motion which drives the coiling arbor at a speed changing from substantially zero to a maximum. Hence, in this case, the cam 92 is shaped to insure a substantially uniform current input to each incree ment length of the coil, as the rate of coiling changes.

Although I prefer to employ an alternating current for the wire conditioning or stress relief, a direct current may be used for some limited purposes, and in that case a variable resistance is employed to vary the current input to the wire and provide a low voltage related to the resistance of the effective portion of the coil. .That is, the transformer 84} may be replaced by a resistance having a rotatable arm employed which sweeps over the resistance coils and. picks off a required amperage.

It will be appreciatd that this invention applies to various types of wire coiling machines used for making both torsion and tension springs as well as other types of coiled articles, in which an electric current input is varied during the coiling operation to insure a required relief of coiling and other stresses in the wire as it is being progressively shaped. It will also be noted that the elec: tric current is applied to a straight portion of the wire in the illustration of Fig. 3 and that the wire may be drawn into a tight coil rather than the loose condition illustrated in Fig. 3 for the sake of clarity, so that the current will be short circuited from the straight stretch of Wire through the tightly wound convolutions of the coil on the arbor. Nevertheless, the wire has been preconditioned so that as it is twisted around the outer portion of that tightly wound mass, the annealing effect is had throughout the first arcuate portion of the coil, so that the conditioning eifect may be considered as takeng place during the coiling stage and particularly because of the residual heat remaining in the rapidly moving wire as the latter is drawn into the coil.

In accordance with this invention, 1. pass an electric current through the wire and condition it for the coiling stress and thus cause a controlled molecular orientation or other electrical and heating effect which relieves the wire drawing and coiling stresses and provides a uniformity of grain structure and restores to the wire much permanent deformation or set. is accomplished while the coiled wire is still in the coil- 7 ofits original potential resiliency and resistance to a The electrical treatment ing machine and before it has been severed from the feed wire, so that the stresses are relieved while the shape of the coil maintained. The electric current has its voltage controlled to provide a current flow related to the size and resistance of the unit length of that portion of the wire being coiled, which will receive the stresses without heating the wire to cause grain growth or other detrimental efiectincident' to the usual normalizing treatment. In this Way, close limits and tolerances may be maintained and springs and other coiled or bent wire objects may be made with a desired uniformity of structure.

The wire may be bent into helical, spiral and other shapes; and the term coil. is intended herein to cover the various related articles and procedures involving bending and shaping a wire that is drawn continuously or intermittently from a supply source and severed after the form has been made. For example, thermostat elements made of a spiral winding of two flat strips of different metals, cigarette lighters formed of a spirally coiled metal strip of suitable electrical resistance, watch and clock springs are usually required to have their coils spaced uniformly. These various and other types of objects, herein termed coiled wire, may have the internal stress relieved, while the wire is being held at a desired diameter, pitch and spacing of the coil convolutions, by subjecting the wire to a controlled electric current of a voltage and amperage in accordance with the procedure defined herein which will relieve stress and presumably effect a molecular polarity orientation while the wire is in the coiling machine and under its initial coiling stress. By using an alternating current, the orientation is effected without causing an appreciable grain growth as may result from the use of an externally applied heat or the heating effect of a direct current. This treatment, therefore, relieves both the stress that is put into the wire while it is drawn as well as the additional stress caused by bending the wire violently to shape it.

It will also be understood that various modifications may be made in the construction within the principles and disclosure of this invention. Hence the above discus sion of the principles of the invention and the description of a preferred embodiment thereof is not to be interpreted as imposing limitations on the appended claims.

Various related features are claimed in my copending applications Serial #546,142 and 546,189, which matured to Patent 2,779,860 on January 1, 1957, filed November 10, 1955.

I claim:

1. A wire coiling machine comprising power driven wire feed rolls, a rotatable arbor, means for reciprocating the arbor, mechanism associated with the feed rolls for rotating the arbor at a rate varying from Zero to a maximum and through a predetermined cycle to coil the wire thereon, means for severing the coil from the wire when the coil has been completed and the wire is stationary, a source of electric current, contact means for introducing the current into a unit length of the wire being coiled and cam controlled means for progressively vary ing the current input in coordination with the rate of arbor rotation so as to provide a predetermined electrical efiect in said unit length of wire.

2. A wire coiling machine comprising power driven wire feed rolls, a rotatable, axially stationary arbor electrically insulated from the feed rolls, means associated with the feed rolls for rotating the arbor through a predetermined cycle and forming thereon a spiral coil at a progressively increasing linear speed of wire movement as the coil diameter increases, means including a sliding contact for introducing an electric current into the moving wire being coiled, and mechanism coordinated with the wire movement for progressively increasing the current input to a unit length of wire as the wire is coiled feed rolls, a rotatable arbor, means for rotating the arbor through a predetermined cycle while it is axially stationary and coiling wire thereon in a spiral of progressively increasing diameter, electrical means for introducing an electric current into a unit length of wire which is being coiled, and cam controlled mechanism for progressively increasing the current input into said unit length as the spiral increases in diameter, so as to provide an increasing stress relieveing efiect in the unit length of wire as the coil diameter increases which reduces .the ultimate recoil and insures a substantially uniform spacing of the wire convolutions.

4. A machine according to claim 3 comprising cam controlled mechanism for severing the coil from the wire while the wire is stationary and cam controlled means operated in timed relation therewith for stopping the current input prior to the wire severance.

5. A wire coiling machine comprising power driven Wire feeding rolls, a rotatable arbor, means associated with the feeding rolls for rotating the arbor intermittently through a predetermined cycle and coiling wire thereon in a progressively increasing coil length, means providing an electric circuit for directly introducing an electric current into said increasing length of wire coil, means coordinated with the wire movement to increase the voltage progressively as the coil length increases and provide a controlled current inputtherein to produce a predetermined electrical stress-relieving effect, and mechanism coordinated with the arbor rotation and wire movement for severing the coil from the wire while the arbor is rotatably stationary.

6. A wire coiling machine comprising power driven wire feeding rolls, a rotatable arbor, means associated with the feeding rolls for rotating the arbor through a predetermined cycle and stopping the same and coiling wire on the arbor in a progressively increasing length, means including a variable voltage transformer for introducing an alternating current directly into the portion of the moving wire to be coiled, mechanism coordinated with the arbor rotation and wire movement for severing the coil from the wire while the arbor is rotatively stationary, and mechanism including a positively operated cam to control the transformer and progressievly vary the current input to the moving wire in coordination with the rate of movement thereof and thus provide a predetermined electrical stress-relieving effect which reduces the ultimate recoil of the coiled wire.

7. A wire coiling machine comprising power driven wire feeding rolls, a rotatable arbor, means associated with the feeding rolls for rotating the arbor through a predetermined cycle and varying the rate of arbor rotation between a minimum and maximum and coiling wire progressively thereon, means for introducing an electric current directly into the moving wire during the coiling operation, a cam mechanism for controlling the current input into the wire and coordinating it with the rate of arbor rotation so as to provide a predetermined electrical stress-relieving effect in a unit length of the wire being coiled, and mechanism coordinated with the arbor rotation and Wire movement for severing the coil on the wire while the arbor is rotatably stationary.

References Cited in the file of this patent UNITED STATES PATENTS 458,115 Thomson Aug. 18, 1891 2,061,105 Ruml Nov. 17, 1936 2,175,426 Blount et al. Oct. 10, 1939 2,491,878 Spagnola Dec. 20, 1949 2,548,735 Meletti Apr. 10, 1951

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