US2531059A - Means and method for treating rubber springs - Google Patents

Description

Nov. 21, 1950 A. s. KROTZ 2,531,059

MEANS AND METHOD FOR TREATING RUBBER SPRINGS Filed Feb. 12, 1944 inmfbll... fi UT? 515550. 2

Patented Nov. 21, 1950 MEANS AND METHOD FOR- TREATING RUBBER-SPRINGS Alvin S. Krotz, Akron, Ohio, assignor to The B. F.

Goodrich Company, blew York, N. Y., a corporation of New York Application February 12, 1944, Serial No. 522,079

I 6 Claims. 1

This invention relates to the treatment of springs of elastic rubber or other rubber-like material.

Torsion springs, comprising a substantially rigid supporting member, a substantially rigid loading member, and a body of elastic deformable material such as soft vulcanized rubber or other rubber-like material between the supporting and loading members and bonded thereto asby vulcanization, are advantageous especially in providing both the support of a vehicle and the cushion for the ride.

It has been found that for a short period after installation and initial loading of such torsion springs, the cushioning material takes the major part of, if not substantially all, the permanent set or apparent creepage it will undergo in service, and a take-up adjustment after a short period of use has ordinarily been'desirable.

The present invention aims to overcome, prior to installation of the spring, its tendency to creep in use, and to provide convenient transportable means and novel procedure for presetting the springs between manufacture and installation.

Objects of the invention are to provide readily transportable means or apparatus for conveniently preloading the springs, preferably transtion thereof, parts of the apparatus and the spring being broken away and parts being shown .in section.

Fig. 2 is a cross-sectional view taken on line 2-2 of Fig. 1. i

Fig.- 3 is a side elevation,- with parts broken away and parts shown in section, of another spring, showing a modified form of presetting means.

Fig. 4 is a similar view showing a further modification of the presetting means and a spring of different construction, parts being broken away.

g. 5 is an end view of Fig, 4.

Fig. 6 is a longitudinal sectional viewof another modification of the setting means and a diii'erent form of spring.

Fig. 7 is a perspective view of another modification, in which setting means is provided for two, springs in combination.

In accordance with the invention the spring is torsionally loaded after manufacture and held under such torsional load fora period prior to installation to reduce the tendency to creep in use, and readily transportable means are provided for holding the spring under such torsional load and, optionally, for adjusting such load, and the spring may be subjected to heat while held in loaded condition to enhance the effectiveness of the treatment. In the illustrative embodiments shown in the drawing, the load-holding or restraining means generally comprises means for detachably engaging the supporting and load ing members of the spring for holding them with relation to each other in torsionally loaded relation, and may include means for adjusting the torsional load. Such restraining means may assume Various forms depending somewhat upon the construction of the spring, and several different forms of means are illustrated.

Referring to Figs. 1 and 2, which show one form of spring and restraining means and con venient mechanism for placing the spring under load, the inner member In of the spring comprises a tubular metal shaft having a key slot 45 in at least one end thereof extending axially of the shaft. The outer member comprises a pair of half-round shell members 13, id, having their axial margins normally spaced from each other to define longitudinally extending spaces l5, l6 therebetween. In use either of the inner and outer members may be the supporting member while the other may be the loading member.

An annular body ll of elastic deformable material, such as soft vulcanized rubber or similar rubber-like cushioning material capable of angular distortion is located between the inner and outer member and is adhered thereto, as by a vulcanized bond. Angular rotative movement of the loading member with respect to the supporting member will place the deformable body under torsional loading. The particular spring shown has one longitudinal margin E8 of one of its shell members extending tangential to the curved portion thereof so as to provide a radially raised shoulder for holding the shell in place when mounted by abutment against a shoulder of the bore in which it is seated. Torsional loading of this spring in a direction to press such raised margin (3i ;llmierentially against a shoulder, not

only prevents rotation of the shell by reason of the shearing strength of the metal, but also by reason of increased friction, due to the tendency of the metal shell to unwind under the tangentially applied load, the shell acting as a selfenergizing brake against its confining housing. The projecting margin l8 may also be utilized to prevent rotation of the outer split shell under torsion during a pre-loading operation, as hereinafter described.

The apparatus illustrated in Fig. 1 is a convenient means for pre-loading the spring and comprises a supporting cradle l9 adapted to engage the outer shell of the spring. A clamping strap 26 has slotted ears 2|. Swing bolts 22 are pivoted to the cradle at each side thereof as by a pin 23 extending through ears'24 of the cradle. The bolts extend through the notches in the ears 2| of the strap 29 and'have nuts 25 threaded thereon whereby the strap may be drawn about the spring, the slots of the clamp ears permitting the bolts to be swung aside when the nuts 25 are turned back a few turns, thereby quickly releasing restraint of the spring.

A spindle 26 is journaled in brackets 21', 28 for rotative and axial movement in alignment with the spring. It has a keyway 29 formed therein. A worm gear 36 is slidably mounted on the spindle but is confined laterally between brackets 21, 28 and has a ke 3| adapted to engage the keyway 29. A worm 32 meshes with Worm gear and drives the spindle from any convenient source of power (not shown).

For moving the spindle axially, a shifter fork 35 is pivotally mounted, as at 36, to bracket 28 and engages between collars 31, 38 fixed to spindle 26. A locking pin 39 is adapted to engage aperture 40 in the frame 4| of the apparatus, on which the cradle l9 and brackets 21, 28 are supported, to lock the spindle in advanced or retracted positions.

For rotating the inner member of the spring, such inner member is formed with an axially extending notch or other driving means adapted to be engaged by a pin or key 46 or other driving means on spindle 26 and the spindle may have a reduced end 4'? adapted to enter the bore of the inner member. The key 46 does not extend beyond the outer face of the inner member so that a retaining means may be slipped over the inner member, or removed therefrom without interfering with the locked engagement of the spindle and the inner member.

For retaining the inner and outer members after loading of the cushion body, a retainer 59 is provided. This retainer is adapted to be removably secured over the inner and outer members in any desired position of loading. In the form of retainer shown in Figs. 1 and 2, the retainer has a bore 5| adapted to slide over the body of the spindle 26 and the inner spring member, and has a counter bore 52 adapted to slide over the outer spring members axially and to limit rotation with respect thereto. Where the outer spring members have an axially projecting shoulder M3, the retainer may be formed with driving notches 53, 54 adapted to receive such shoulders and to engage them by rotative adjustment of the retainer. A set-screw 55 is threaded through the retainer to clamp the retainer to the inner spring member. The arrangement is such that the retainer may be slipped axially over the end of the spring. With e p n clamped to the cradle, the spindle 2s may be advanced so that its key enters the driving slot 45. The set screw 55 may be backed off and the spindle 26 rotated the desired amount to load the cushion body of the spring. The set screw may then be tightened and the spindle 26 withdrawn leaving the spring under load.

When it is desired to change the load after the retainer is in place, a retainer such as that illustrated in Figs. 4 and 5 may be employed. Here the retainer comprises a cap 69 axially slotted as at GI, 62 and adapted to be slipped axially over the outer member of a spring, and a separate collar 63 is adapted to slide over the inner member of the spring. An ear 64 is formed on the cap and an arm 65 is formed on the collar 63. A screw 66 is threaded through the arm 65 and impinges against the ear 64. For securing the collar 63 to the inner spring member, means, such as a pin 61 passing through aligned openings in the collar and the inner spring member, is provided. The spring shown in Figs. 4 and 5 with this retainer, has projecting flanges 68, 69, 10, H, at the margins of its outer shell members, which engage the opposed slots SI of the cap. The retainer may be secured over those fiangs and the collar 63 may be secured to the inner member either before or after loading the cushion body. When it is secured before loading, loading is accomplished by rotating screw 66 and when the loading means of Fig. 1 or a similar means is employed to load the spring torsionally, the spring may be secured after loading and the screw 66 then used to increase or decrease the torsional load.

In the retaining means illustrated in Fig. 3, a one-piece retainer cap 15 has a splined or serrated bore 16 adapted to slidably engage over a splined surface I! of the inner spring member, and a counterbored portion 18 adapted rotatably to engage over the outer spring member. This from of spring and retainer may be assembled by use of .a loading means similar to that of Fig. 1. the spindle having a serrated cup to fit over the end of theinner spring member instead of engaging the member from within. After loading, screws 80, 8| threaded through the retainer may be tightened against the outer members 82, 83 of the spring.

In the spring shown in Fig. 6, an outer shell 85 of metal has integral inwardly turned ears 86, 87, and the inner member 88 is tubular and is supported from within by a spider 89 having a serrated bore 90. The retaining means comprises a serrated plug 9| adapted to fit the serrated bore and having arms 92 extending radially outwardly thereof. The arms 92 have apertures in alignment with the ears 86, 8! and rivets or pins 93 may be employed to secure the arms to the ears after loading the cushion body torsionally.

After application of the retaining means, the spring may be stored or transported with the retainer in place so that creep or permanent set of the cushion material is conveniently accomplished during storage and shipment and the spring is ready to install at their destination in a condition for minimum tendency to creep in use.

The invention also makes possible immediate loading of the cushioning body after molding thereof and before the molding heat has been dissipated from the spring so that the heat may be utilized to accelerate removal of creep and permanent set, Too rapid a loss of heat may be prevented by packing the loaded spring in a closed container of heat insulating material so that heat treatment is extended.

In some cases it may be desirable to stress a plurality of springs together, for example in pairs, in accordance with the embodiment of Fig. 7. Here, a pair of springs I and Hill are of a kind having respective inner shafts I02, )3, outer sleeves I54, I05, and bodies H16, fill of resilient rubber or other rubber-like material interposed and bonded to the respective shafts and sleeves, and provided with extending arms H18, H39 integral with the respective sleeves I04, 105. The shafts of the two springs are locked together as by a brace or bracket member H0 having apertures to receive the shafts and set screws Hi and H2 adapted to bear against the shafts. A second brace or bracket member H3 has apertures receiving the other ends of the two shafts and may also have set screws, indicated at H4, H5, for engaging the shafts to assist in holding them against rotation. These set screws Hi, H5 may however be omitted when the shafts are locked at their other ends.

An end plate 8 i6 is adapted to be applied to the ends of the arms 108, I99 when the latter are swung to a position of adjacency to stress the springs rotatively, one clockwise and the other counter-clockwise. The end plate H6 may be connected with the brace i it by an extension H! which fixes the springs in definite relative positions. Fastening means such as screws H8, H9 hold the arms to the end plate H6. In this manner the pair of springs is stressed as a compact transportable unit, and inasmuch as both springs may thus be stressed and retained under the same conditions and for the same period of time, this is of advantage especially in providing matched springs in pairs for the two front Wheels of the same vehicle, or the two rear wheels thereof.

In the use of any of the retaining and packaging means shown, the spring may be torsionally loaded directly after vulcanization of the cushion body or later if desired, and the retainer applied without releasing the loading force, and the spring may be transported and stored in loaded condition. Thereafter upon installation the retainer may be removed and returned for reuse on another spring. If desired in some cases the spring may be installed without relieving the spring of its torsional loading, the weight of the vehicle being applied before the release, so that the spring remains stressed continuously from manufacture through transportation, storage, installation and on into use.

Variations may be made without departing from the scope of the invention as it is defined by the following claims.

I claim:

1. The method of treating an assembly of parts for providing a torsion spring having inner and outer supporting and loading members with a cushioning body of resilient rubber-like material therebetween and bonded thereto to reduce tendency of the spring tocreep rotatively in use, which method comprises subjecting the assembly to a molding and vuloanizing operation under heat and pressure, loading the cushioning body while it still retains heat of the molding and vulcanizing operation but prior to installation of the spring by relative rotative displacement of said members, securing the members in their displaced relation, insulating the spring to delay cooling of the spring over a period of time preceding the installation of the spring sufficient to reduce the tendency to creep after installation, and installing the spring after the tendency to creep has been reduced.

2. A torsion spring package transportable between manufacture and installation comprising a spring having inner and outer members with a body of resilient'rubber-like material therebetween and bonded by vulcanization thereto, and means transportable with the spring for engaging said inner and outer members of thespring to maintain the inner and outer members rotatively displaced relative to each other with said resilient material in a relatively stressed condition, said means comprising a holding structure mounted in gripping relation to the inner member and extending radially outward at an end of the spring and having an outer portion mounted in gripping relation to the outer member of the spring for resisting relative rotation of said members in the torsionally stressed condition.

3. A torsion spring package transportable between manufacture and installation comprising a spring having inner and outer members with a body of resilient rubber-like material therebetween and bonded by vulcanization thereto, and means transportable with the spring for engaging said inner and outer members of the spring to maintain the inner and outer member rotatively displaced relative to each other with said resilient material in a relatively stressed condition, said means comprising a holding structure having a cupped portion overlying the outer member of the spring at an end thereof in gripping relation to said outer member and having a tubular portion engaging over the inner member of said spring at an end thereof and nonrotatively securedthereto for resisting relative rotation of said members in the torsionally stressed condition.

4. A torsion spring package transportable between manufacture and installation comprising a spring having inner and outer members with a body of resilient rubber-like material therebetween and bonded by vulcanization thereto, and means transportable with the spring for engaging said inner and outer members of the spring to maintain the inner and outer member rotatively displaced relative to each other with said resilient material in a relatively stressed condition, said means comprising a holding structure having a flange secured to the outer member of the spring at an end thereof and having a portion extending within the inner member of said spring and secured thereto in non-rotative relation thereto for resisting relative rotation of said members of the spring in the torsionally stressed condition.

5. A torsion spring package transportable between manufacture of torsion springs and installation thereof, said package comprising a pair of torsion springs each comprising an inner shaft and an outer sleeve structure and a body of resilient rubber-like material therebetween and bonded by vulcanization thereto with the sleeve structure of each spring having a projection extending transversely thereof, said springs being disposed in side-by-side relation with the shafts and sleeves generally parallel to one another, and means transportable with the springs for looking the shafts of the springs against rotation and for locking the projections in positions to main-' tain the sleeve structure of each spring rotatively displaced relative to its shaft with said rubberassumes like: material: of each' spring? ina rotati'vely stressedicondition, saidimeans comprising a holding structure at an end of said springs with means associated therewitlr for locking said shaftsagainst' rotation with respect to said holding. structure; and a second holding structure connecting said; projections to resist rotation of said sleeve structures relative.- to said shafts when said springs are'held: b said holding structures int a condition of stress tending to cause such rotation.

61 Av torsion spring package transportable between manufacture of torsion springs and installationtheeof, said package comprising a pair of torsionsprings each comprising an inner shaft and: an: outer sleeve structure and a body of resilient rubber-like material therebetween' and bonded byv-ulcanization thereto with the sleeve structureof each spring having a projection extending transversely thereof, said springs being disposed in side-by-siderelation with the shafts and sleeves generally parallel to one another, and means transportable with the springs for locking the shafts of the springs against rotation and for looking the projections in position to maintain the sleeve structure of each springrotativel'y displaced relative to its shaft. with saidrubber-like material of each. spring in a rotatively stressed REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date:

1,358,878- Rinn, Jr -Nov. 16, 1920 1,951,805 Ferris Mar. 20-, 1934 1,951,825 Ferris Mar; 20, 1934 1,964,735 Knox et-al July 3, 1934 23051 864 Knoxet a1 Aug. 25,1936 2,110,783 Welker Mar. 8, 1938 2,215,134 Rehnberg y Sept. 17, 1940 2,231,769 Merrill Feb. 11, 1941 2,286,609 Ledwinka June 16, 1942

Claims (2)

1. THE METHOD OF TREATING AN ASSEMBLY OF PARTS FOR PROVIDING A TORSION SPRING HAVING INNER AND OUTER SUPPORTING AND LOADING MEMBERS WITH A CUSHIONING BODY OF RESILIENT RUBBER-LIKE MATERIAL THEREBETWEEN AND BONDED THERETO TO REDUCE TENDENCY OF THE SPRING TO CREEP ROTATIVELY IN USE, WHICH METHOD COMPRISES SUBJECTING THE ASSEMBLY TO A MOLDING AND VULCANIZING OPERATION UNDER HEAT AND PRESSURE, LOADING THE CUSHIONING BODY WHILE IT STILL RETAINS HEAT OF THE MOLDING AND VULCANIZING OPERATION BUT PRIOR TO INSTALLATION OF THE SPRING BY RELATIVE ROTATIVE DISPLACEMENT OF SAID MEMBERS, SECURING THE MEMBERS IN THEIR DISPLACED RELATION, INSULATING THE SPRING TO DELAY COOLING OF THE SPRING OVER A PERIOD OF TIME PRECEDING THE INSTALLATION OF THE SPRING SUFFICIENT TO REDUCED THE TENDENCY TO CREEP AFTER INSTALLATION, AND INSTALLING THE SPRING AFTER THE TENDENCY TO CREEP HAS BEEN REDUCED.

2. A TORSION SPRING PACKAGE TRANSPORTABLE BETWEEN MANUFACTURE AND INSTALLATION COMPRISING A SPRING HAVING INNER AND OUTER MEMBERS WITH A BODY OF RESILIENT RUBBER-LIKE MATERIAL THEREBETWEEN AND BONDED BY VULCANIZATION THERETO, AND MEANS TRANSPORTABLE WITH THE SPRING FOR ENGAGING SAID INNER AND OUTER MEMBERS OF THE SPRING TO MAINTAIN THE INNER AND OUTER MEMBERS ROTATIVELY DISPLACED RELATIVE TO EACH OTHER WITH SAID RESILIENT MATERIAL IN A RELATIVELY STRESSED CONDITION, SAID MEANS COMPRISING A HOLDING STRUCTURE MOUNTED IN GRIPPING RELATION TO THE INNER MEMBER AND EXTENDING READIALLY OUTWARD AT AN END OF THE SPRING AND HAVING AN OUTER PORTION MOUNTED IN GRIPPING RELATION TO THE OUTER MEMBER OF THE SPRING FOR RESISTING RELATIVE ROTATION OF SAID MEMBERS IN THE TORSIONALLY SRESSED CONDITION.

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