US3540641A - Web accumulator - Google Patents

Description

United States Patent [54] WEB ACCUMULATOR 11 Claims, 5 Drawing Figs,

[52] US. Cl 226/1,

226/118, 226/195, 242/753 [51] Int. Cl B6Sh 23/10 [50] Field ofSearch 226/1, 195,

[56 References Cited Primary ExaminerAllen N. Knowles Att0meys-T J. Morgan, S. D. Murphy and Louis Gubinsky ABSTRACT: A web accumulator for maintaining approximately uniform tension in an advancing web. The accumulator has a pair of opposed arms which are mounted for swinging movement at opposite ends of a frame. The arms each have a plurality of rollers at spaced intervals. The web is conducted alternately over a roll at the outer end of one arm and a roll at the inner end of the other arm and progressively back and forth over the rollers of both arms and then off of the frame at the opposite end. The arms swing in coordinated relation to provide wide variation of spacing. A power device applying torque to the arms causes the armsto swing when the tension in the web changes.

Sheet 2 013 v VQ/ Patented Nov. 17, 1970 BACKGROUND OF THE INVENTION This invention relates to web accumulators, and more particularly to apparatus for accumulating slack in a forward or reverse traveling web. More specifically, the web accumulator of the present invention can be used for maintaining substantially uniform tension in advancing webs, as well as accumulating slack during necessary backwinding operations, i.e. during packaging a broken end feeds onto the beam requiring backwinding toward the creel without a decrease in tension.

Various web accumulators have been used in the textile and other industries for taking up slack in an advancing web of material. Typically, a weighted roller or series of rollers are mounted for vertical reciprocating movement in a frame, and the web is conducted alternately over a movable roller and stationary roller at opposite ends of the frame. As the tension of the web decreases, a counterweight causes the movable roller to drop until the slack is taken up and the tension is thereby adjusted. Similarly, if the tension increases, the movable roller is displaced upwardly toward the stationary roller to decrease the tension. Usually, there are several movable rollers and stationary rollers in the accumulator. These accumulators inherently induce considerable tension in the web as the web passes over the movable and stationary rollers. Often there are a great many rollers and in order to pull the web through the accumulator, it is necessary to maintain relatively high tension in the web.

Another difficulty with these conventional web accumulators is that they are normally unable to respond to small changes in tension due to the large inertia of the counterweight and the movable roller assembly. Usually, the adjustment of tension that can be achieved by these conventional accumulators is limited to large changes in tension. The inertia effect of these conventional accumulators also may impose rapid increase in tension in the web when the movable rollers are being displaced downwardly and the web tension, which previously was decreasing, suddenly increases before the rollers can take up the slack and arrest the downward motion of the rollers. This effect may be so severe that the web breaks.

Accordingly, it is an object of this invention to provide an improved web accumulator.

It is a furtherobject of this invention to provide a web accumulator that is capable of providing a large variation in web length traversing the accumulator.

A further object of this invention is to provide an accumulator that has relatively low inertia to provide a rapid response to variations in tension in the web.

Another object of this invention is to provide an accumulator that minimizes frictional drag on the web as it passes through the accumulator.

Still a further object of this invention is to provide a web accumulator which can function advantageously during forward or reverse winding operations.

SUMMARY OF THE INVENTION These objects are accomplished in accordance with a preferred embodiment of the invention by a web accumulator having a pair of arms mounted at opposite ends of a frame. The arms each have a plurality of rollers spaced lengthwise of the arms. One arm is mounted for pivoting movement upwardly from a median plane while the other arm is mounted for swinging movement downwardly from the median plane. Rollers at opposite ends of the frame guide the web from one end of the frame to the other and the rollers on the arms are spaced on opposite sides of the median plane. so that when the arms are closed together, the web passes across the median plane without engaging the rollers on the arms.

Power means is provided on the frame for swinging the arms away from each other. The axles on which each arm is mounted are joined together by a chain drive and the power means applies a substantially constant torque to the axlesJThe power means is also used to swing the arms toward each other to disengage the rollers from the web.

DESCRIPTION OF THE DRAWINGS This preferred embodiment is illustrated in the accompanying drawing in which:

FIG. I is a perspective view of the web accumulator of this invention;

FIG. 2 is a side elevational view of the web accumulator;

FIG. 3 is a schematic view of the web accumulator showing the arm rollers disengaged from the web;

FIG. 4 is a schematic view of the web accumulator showing the arm rollers partially engaged with the web; and

FIG. 5 is a schematic view of the web accumulator showing the arm rollers fully engaged with the web.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. l and 2, the web accumulator includes a rectangular frame 2 having a base 4 which supports upright legs 6 at each corner. At the front end, the upper portions of the legs 6 are joined by a cross brace 8 and diagonal braces 10. At the rear end of the frame, a cross brace 12 and diagonal braces 14 rigidly maintain the legs 6 in an upright position. Longitudinal side braces 16 join together the tops of the legs 6. Corner braces 18 are provided for reinforcing the joints at each corner of the frame.

At the front end of the frame 2, a pair of brackets 20 are secured adjacent the top of the legs 6 and an entrance roller 22 is journaled at opposite ends in the brackets 20. At the rear end of the frame 2, a pair of brackets 24 are secured adjacent the top of the legs 6 and an exit roller 26 is journaled for rotation on the bracket 24.

A shaft 28 extends across the frame 2 and the opposite ends of the shaft 28 are journaled in bearings provided in the corner braces 18. Intermediate support for the shaft 28 is provided by bearing supports 30 extending outwardly from the cross brace 12. An arm 32 is mounted for swinging movement on the shaft 28. The arm includes a pair of side members 34 joined together by end members 36. The arm 32 includes a pair of support members 38 which are rigidly secured on the shaft 28.

At the front of the frame 2, a pair of brackets 40 are secured on the longitudinal members 16 and a transverse shaft 42 is journaled at opposite ends in the brackets 40. An upper arm 44 is mounted on the shaft 42. The arm 44 includes a pair of side members 46 joined together by end members 48. The arm 44 is rigidly secured on the shaft 42 by means ofsupports 50.

The web is guided between the arms 32 and 44 by a plurality of takeup rollers 52 and 54 which are mounted on the upper and lower arms 44 and 32, respectively. The rollers 52 on the upper arm are journaled for rotation at their opposite ends on brackets 56 which project downwardly from the side members 46. The rollers 54 are journaled at their opposite ends for rotation between brackets 58 which project upwardly from the side members 34. As shown in FIG. 2, the brackets 56 and 58 are spaced relative to each other so that the rollers of one arm are positioned between the rollers of the other arm and the rollers 52 of the upper arm 44 are positioned below the median plane defined by the entrance roller 22 and the exit roller 24, while the rollers 54 of the lower arm are above the median plane when both of the arms are in the position shown in full lines in FIG. 2.

Swinging movement of the upper and lower arms 44 and 32, respectively, is coordinated by an endless drive chain 60. A sprocket 62 is rigidly secured on the shaft 42 and another sprocket 64 is rigidly secured on the shaft 28. The drive chain 60 extends over the sprockets 62 and 64, so that rotation of the shaft 28 is transmitted to the shaft 42. The end of the shaft 28 projects outwardly from the corner brace 18 and a gear 66 is secured on the end of the shaft 28. A double acting fluid cylinder 68 is mounted on the side of the leg 6 and a rack 70 is provided on the piston rod of the cylinder 68. When fluid is admitted to the head end of the piston in the cylinder 68, the piston rod moves upwardly, thereby causing counterclockwise rotation of the shaft 28 by means of the gear 66. When fluid is admitted to the rod end of the piston in the cylinder 68, the shaft is rotated in a clockwise direction by the rack 70.

In operation, the web is threaded through the accumulator from left to right, as viewed in FIG. 2. With the arms 32 and 44 in the position shown in full lines in FIG. 2, the web 72 passes over the top of the entrance roller 22 and extends approximately horizontally lengthwise of the arms and leaves the accumulator by passing under the roller 26. Since the rollers 52 of the lower arm 32 are above the web 72 and the rollers 54 of the upper arm 44 are below the web, the web does not engage either of these sets of rollers when the arms are arranged approximately horizontal. This condition is illustrated schematically in FIG. 3. Of course, it is assumed that there is sufficient tension in the web to maintain the web approximately straight, so that it does not sag between the rollers 22 and 26.

Initial tension loading is applied to the web by conducting fluid under pressure to the head end of the cylinder 68, thereby causing the rack 70 to be displaced upwardly. This movement causes counterclockwise rotation of the gear 66 and the corresponding rotation of the shaft 28 swings the lower arm 32 downwardly until the outermost roller 54 engages the web 72. Rotation of the shaft 28 is transmitted to the shaft 42 by the sprocket chain 60, thereby causing the arm 46 to swing upwardly at approximately the same angle with respect to the median plane as the lower arm 32, thus bringing the outermost roller 52 into engagement with the web 72. This condition is illustrated schematically in FIG. 4,

Further swinging movement ofthe arms 32 and 44 by means of the fluid cylinder 68 causes the arms to swing further apart until the position shown schematically in FIG. is reached. In this position, the length of travel of the web between the entrance roller 22 and the exit roller 26 is considerably greater than that shown in FIGS. 3 and 4. The force of the cylinder 68, is used to maintain a substantially constant torque on the arms 32 and 44. Preferably, the force on the piston rod 70 is adjusted by means of the fluid pressure in the cylinder 68 to maintain the arms approximately midway between the positions shown in FIGS. 4 and 5 during normal operation. The accumulator can be rendered inactive by swinging the arms back to the position shown in FIG. 3, without removing the web 78 from the accumulator.

The web accumulator of this invention provides effective control over the tension in an advancing web, without imposing excessive drag on the web. By hinging the arms at opposite ends of the frame 2, the initial points of engagement of the web by the rollers 42 and 54 are widely spaced apart. Consequently, the angle of deviation of the web path from the median plane of the web 72, as followed by the web in FIG. 3, is less than it would be if both arms were hinged at the same end of the frame. The parallel mounting of the arms and the sprocket chain connection between the arm shafts provides maximum variation in web travel through the accumulator, i.e. maximum web takeup per unit area. Also, the accumulator may be constructed of conventional structural elements and is economical to manufacture and to operate. Thus the present accumulator is readily distinguishable over prior art devices wherein both arms pivot on the same side of the frame and which further require frictional engagement at rest, such devices operating in accordance with different mechanical principles not involving functionless yarn travel through a median plane and web engagement by a plurality of rollers advancing from opposing arcs.

i While this invention has been illustrated and described in one embodiment, it is recognized that variations and changes may be made therein without departing from the invention as set forth in the claims.

I claim:

I. Apparatus for adjusting tension in an advancing web of flexible material comprising:

base means, a pair of arm members, means hingedly mounting said arm members on said-base means for swinging movement relative to said base means, the hinge axis of one of said arm members being spaced apart from the hinge axis of the other arm member and being substantially parallel thereto, yarn guide means attached to said base means defining a yarn path;

each of said arm members having a plurality of pulleys mounted for rotation thereon, said pulleys of one arm member being spaced in one direction from the hinge axis of said one member, said pulleys of the other arm member being spaced in the opposite direction from said hinge axis of said other member, said pulleys of each arm member being transpositionable across the path of travel of said web; and

means for coordinating swinging movement of said arm members to maintain said members in substantially parallel relation during swinging movement, and power means for swinging said arm members, whereby the slack in a web threaded between said pulleys may be taken up by swinging said arm members to increase the length of the path of said web in passing over said pulleys.

2. The web tension apparatus according to claim I, wherein said arm members span substantially the entire distance separating said hinge axes.

3. The web tension apparatus according to claim 1 wherein said arm members each include a rectangular frame, said pul ley axes are positioned in a common plane for each member.

4. The web tension apparatus according to claim 3 wherein said arm members swing between a first position and a second position, said pulleys of one member being closer to said pulleys of the other member in said first position than in said second position, whereby when said arm members are in said first position a web passes through the space between said arm members without engaging said pulleys and swinging movement of said arm members toward said second position causes said pulleys to engage said web progressively from the end of said member opposite said hinged end, said pulleys of each arm member being spread toward the hinge axis of said other member and being displaced across the plane of travel of said web when in said first position.

5. The web tension apparatus according to claim 4 including guide means on said base means, said guide means being positioned adjacent each of said member mounting means for guiding a web into the space between said members.

6. Apparatus for applying tension to an advancing web of indeterminate length comprising:

a supporting base having opposite ends and opposite sides, a

pair of arm members, each of saidarm members including a flat rectangular frame;

means hingedly mounting one of said arm member frames at one end of said base, means hingedly mounting the other of said arm member frames at the opposite end of said base, said mounting means permitting swinging movement of said frames between a first position with said frames in close proximity to each other and a second position with said frame spaced apart;

a plurality of pulleys on each of said frames, said pulleys being spaced apart from each other, pulleys on said one frame being spaced on one side ofa median plane that extends from end to end of said base and pulleys on said other frame being spaced on the opposite side of said median plane when said frames are in said first position, said pulleys being transpositionable across said median plane to reach said second position;

a pair of guide pulleys, means mounting said guide pulleys at opposite ends of said base adjacent said frame mounting means, said median plane being substantially tangent to said guide pulleys; and

means for maintaining concurrent swinging movement of I said frames relative to said base, and power means for swinging said frames relative to said base to move said pulleys across said median plane to reach said second position.

7. The apparatus according to claim 6 wherein said frame mounting means includes a shaft extending transversely of said base means, said one frame shaft and said pulleys carried by said one frame being on said opposite side of said median plane, and said other frame and said pulleys carried by said other frame shaft being on said one side of said median plane.

conducting a web of material of indeterminate length over i pulleys at opposite ends ofa base, said base having a plurality of spaced takeup rollers on each of a pair of arms hingedly mounted at opposite ends of the base;

engaging said web initially by the takeup roller spaced outermost from the hinged end of both arms and progressively engaging said web by additional ones of said rollers when said web tension is decreasing;

disengaging said web progressively from said additional rol lers before said outermost roller when said web tension is increasing; and

applying torque to said arms to counteract the tension in said web.

10. The method according to claim 9 wherein said en aging and disengaging is accomplished by swinging said arms about axes spaced on opposite sides of the path of said web when said web is supported solely by said pulleys.

11. ln a method for accumulating a plurality of ends ofcon tinuous filaments or continuous filament yarns advancing from respective creels to a beam wherein the improvement comprises:

conducting said filaments over pulleys at opposite ends of a base, said base having a plurality of spaced takeup rollers on each of a pair of arms hingedly mounted at opposite ends of the base; and

engaging said filaments initially by the takeup roller spaced outermost from the hinged end of both arms and progressively engaging said filaments by additional ones of said rollers when accumulating said filaments and disengaging said filaments progressively from said additional rollers before said outermost roller when decreasing said degree of accumulation.

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