US3414020A - Warp-tension equalization mechanism for travelling-wave shedding looms - Google Patents

Description

Dec. 3, 1968 H. FEND WARP-TENSION EQUALIZATION MECHANISM FOR TRAVELLING-WAVE SHEDDING LOOMS 5 Sheets-Sheet 1 Filed July 25, 1966 INVENTOR.

H. FEND ALIZAT Dec. 3, 1968 WARP- SION E ION MECHANISM FOR T A ELLI AVE SHEDDING LOOMS 5 SheetsSheet :2

Filed July 25, 1966 INVENTOR.

H. FEND WARP-TENSION EQUALIZATION MECHANISM FOR I Dec. 3, 1968 TRAVELLING-WAVE SHELDING LOOMS 5 Sheets-Sheet Filed July 25, 1966 INVENTOR. BYL),u-.A l/ M United States Patent 3,414,020 WARP-TENSION EQUALIZATION MECHANISM FOR TRAVELLING-WAVE SHEDDING LOOMS Heinrich Feud, Uster, Zurich, Switzerland, assignor to Oerlikon-Buhrle Holding AG, Zurich, Switzerland Filed July 25, 1966, Ser. No. 567,607 Claims priority, application Switzerland, June 27, 1965, 10,509/65 19 Claims. (Cl. 139--12) ABSTRACT OF THE DISCLOSURE A travelling-wave shedding loom having a number of heddle frames side by side and groups of warp threads of a width corresponding to the width of the heddle frames. A warp thread tension device individually controls the warp tension of each group of warp threads. Tension equalization means are arranged between the tension devices and provide that the same force is extended by each of the tension devices to produce the equal warp thread tension. This tension equalization can be attained by cable hydraulic or pneumatic means.

Travelling-wave shedding looms (sometimes called wave-weaving looms) employing heddle frames encounter a problem not present with conventional looms, namely, the equalization of the warp tension between two neighboring heddle frames. Since the heddle frames necessarily assume different vertical posit-ions as required by the wave shape of the shed formation, there results, unless preventive measures are taken, a varying Warp tension in each heddle frame, in dependence on the instantaneous position of the warp sheet. Because of the varying tension, there arises in the neighboring regions of the interlacing edge a varying tension, which causes a step-like distortion of the interlacing edge. This is a serious fault in weaving and causes, according to the interlacing, more or less pronounced stripes in the weaving pattern at the separation between heddle frames. There is also the danger that individual threads will slacken at this separation and can be pulled from the shuttles.

It has been suggested to solve this problem by use of a resilient tension equalization device similar to the tension beam of conventional looms, for each heddle frame width. The arrangement has the disadvantage that the warp tension actually is not held constant, because the tension of a spring increases with compression or stretching. Moreover, it is diflicult simply to adjust all springs to the same tension.

Two embodiments of the invention will now be described in detail, with reference to the accompanying drawings, wherein:

FIG. 1 is a side view of a travelling-wave shedding loom incorporating the invention, with side panels removed;

FIG. 2 is a side view of the invention on expanded scale, taken along line II--II of FIG 3;

FIG. 3 is a front view, partly in cross section, of the invention, taken along line IIIIII of FIG 2;

FIG. 4 is a top view of the guide roller arrangement, with cover plate removed; and

FIG. 5 shows a hydraulic equalization as a second form of the invention.

Referring to FIG. 1, the travellingwave shedding loom has a warp beam 11 with a drive 12 and control gearing 13. The warp threads 14 run from the beam over a guide roller 15 to the warp stop-motion device 16, from which they continue to a tension equalization lever 17 and thence to the heddle frames 18, which form the shed 19 in which the shuttles 20 move. The reed 21 beats up the weft at the fell 22 of the fabric. The woven fabric 23 continues over control and pressure rollers 24, 25 to the cloth beam 26, where it is taken up. The drive mechanisms for the shuttles and heddles are indicated by reference numerals 27, 28, respectively. The tension equalization mechanism is mounted on a transverse support 29, and a cable 30 runs from the mechanism to a lever 31, to which it is fixed. The lever 31 turns on a pivot 32 which is fixedly mounted on the loom frame. A fluid piston 33, acted upon by compressed air p and moving into a compressed-air cylinder 34 also fixedly mounted on the loom frame, presses on the top surface of lever 31. A lever 66 provides a control connection between lever 31 and control gearing 13. The pressure in cylinder 34 can be held constant at any desired value.

FIGURES 2-4 illustrate the complete tension equalization mechanism on expanded scale. There is one tension equalization lever 17 for each heddle frame width. Each lever 17 carries an upper and lower crossarm, 35 and 37, respectively, which terminate in disks 36, 38. A lever 17 is mounted by means of a sleeve 39 for pivoting on a continuous shaft 40, which, in turn, is mounted on the transverse support 29 by means of a support 41.

A nose 42 of a lever 17 acts on an individual slide 43, which is held in vertical position by a cover plate 44 and longitudinally guided by pins 45, 46. The pins move in guide slots 47, 48 of plate 44 and rest with an en larged head on support 29. Pin 46 also serves as the support point for a movable grooved wheel 49.

The arrangement of the wheels is seen at FIG. 4. A series of pins 50 are fixedly mounted on the support 29, and serve together (in a manner not further illustrated) to secure the cover plate 44, which has been removed in FIG. 4 for illustrative purposes. Thus, the guide slots 47, 48 are not shown. The pins 50 also serve as support points for a series of grooved wheels 51.

At the upper pin 45 of each of the first and last slide 43a a grooved wheel 52 is connected], the diameter of which is smaller than the diameter of the other grooved wheels 49. In the drawing, there is illustrated only the last slide 43a of these two slides. These slides 43a are connected to the crossarms 35, which guide the Warp threads on the edges of the fabnic. As there are guided on this first and last crossarm accordingto the width of the fabric more or less warping threads, but always less than on the other crossarms 35 the loading of the first and last crossarms 35 are less than of the others.

The sizes ofthe grooved wheels 51 and 49 are chosen so that the cable length between the wheels 51 and 49 are parallel toone another, i.e. the angle of winding of the cable around the wheels 49 and 51 is exactly whereas the angle of winding of the cable 30 around the wheel 52 is substantially smaller. Whereas the angle of winding the cable 30 around the wheel 49 depends on the position of the wheel 49, as the cable lengths are parallel to one another, the angle of winding of the cable around the wheel 52 depends on the position of the wheel 52. The greater the force, which the warp threads exerts on the slides 43 and 43a the greater the angle of winding and the greater the force, which the cable 30 exerts on the wheel 52. Therefore the angle of winding the cable around the wheel 52 depends on the number of warp threads, which are guided over the first and last crossarm 35. The cable 30 passes over the wheels 51 and under the wheels 49, 52.

The manner of operation of the tension equalization mechanism will now be described.

The warp threads 14, led over the pivotally mounted tension equalization lever 17, are separated into groups by the disks 36, such that each crossarm 35 carries exactly the number of warp threads needed for the width of a heddle frame section. The warp threads, which are under tension, exert a forward pull on the lever 17, which bears with its nose 42 on the slide 43. The slide acts on the cable 30 by means of the pin 46 and wheel 49, and is responsible for a pull on the cable that corresponds to the warp tension.

All of the levers 17 act similarly on the cable, but the resulting cable tension is not equal to one-half of the slide force. It is thus important that individual slides can assume positions other than those shown, without, however, changing the force relationship.

When a shed is formed, the warp threads are shortened and the lever 17 associated with that shed moves forward and is thus placed under a constant reversely directed force from the cable 30, which, it is assumed, is pulled, at the end of the series of wheels (that is, at the righthand A), by a constant force obtained by compressed air or a weight, for example. The warp tension is thus not altered. But the lever movement does require an additional length of cable, which can be obtained either by drawing up the cable end or by an opposite movement of one or more neighboring levers 17.

In accordance with the invention, the constant pull can be applied to both ends of the cable, or to only one end (as just described) and the other end either made fast to a stationary point, or preferably, connected to the end of the cable to which the force is applied.

Since the heddle movement is very quick and since the heddles along the fabric width are in diiferent positions of their movement at any given moment, the tension in the cable is equalized, although not necessarily to the end wheels. The equalization is achieved despite the fact that the friction ratios cause a certain amount of damping. The cable tension is also equalized when both ends A of the cable 30 are fixed. An equalized warp tension is obtained between two neighboring levers and, indeed, over the entire width of the fabric for various positions of the heddles. Here the amount of the warp tension, which may be regulated by variable braking of the Warp beam, for example, is of no consideration. Whatever the warp tension, the desired equalization is obtained.

In order to facilitate a quick equalization of the warp tension from one lever 17 to the next, the wheels 49, 51 have a center hole appreciably larger than the pins 46, 51. Consequently, for short, quick movements these wheels roll on the surfaces of the pins, and only for the longer movements of the slides 43 do they slide over these surfaces. The warp tension equalization compnises chiefly the former kind of movement, control of the warp let-off the latter.

Because the fabric width is not always exactly equal to the heddle width, it can occur that only part of the last heddle frame at a fabric edge is threaded and thus only part of the crossarm 35 of the lever 17 for that heddle frame is occupied with warp threads. As a result, this lever would not be in balance with the others; because, although the same cable tension acts on it as on the others, the warp tension should not be greater here than anywhere else. To ensure that this lever is in balance with the others, the wheel 52 of the corresponding slide 43 is held by the upper pin 45, and has a smaller diameter and central hole than the wheels 49 held by pins 46. The cable 30 passes over the wheel at such an angle that the component of force, from the cable tension transmitted to the slide in its longitudinal direction is less than is the case with the other slides. Since the warp tension remains constant and causes an equal oppositely directed force from the cable, the slide 43a moves forward and wheel 52 assumes a position at which the two opposed forces are equal. If the warp tension is great, the wheel 52 takes, for example, the position 52' shown in broken line.

Since the tension in the cable and the warp are mutually influential, the cable 30 is not fixedly held at A, but is placed, at least at one end, as already explained, under a definite tension obtained by means of the lever 31 (H6.

l) and compressed air cylinder 34. The pressure p of the compressed air fed the cylinder determines the warp ten sion. Weights of various amounts hung from the cable end could be substituted for the lever 31 and cylinder 34. The pressure p is generated by a compressor or a fluid pump and is held constant by a pressure reducing valve.

The position of lever 31 (or of the weights) can be sensed to provide a control of the warp beam 11. If too much warp should be payed out, all levers 17 will move rightwards (FIGS 1, 2). The slides 43 with their sheaves 49, urged by the tensed cable, move with the levers, leaving free a certain length of the cable 30, which is pulled down by the lever 31 under action of the piston 33. The change in position of the lever 31 can then be used, in a manner not further illustrated or described, to control the warp let-off gearing 13, which is adjusted to pay out less warp or, in the opposite case, more warp.

Referring to the embodiment shown at FIG. 5, a series of fluid pistons 60 are arranged in a common hydraulic chamber 61 filled with a substantially incompressible hydraulic fluid 62 and having a further piston 63. The tension equalization levers 17, shown only schematically, bear on individual ones of the pistons 60. A lever 64, turning on a pivot 65, acts on the piston 63. The lever is in physical contact with the piston 33 and also connected to the lever 66, which acts on the gearing 13.

The form of the invention operates in the same way as the previous form. The fluid 62 exerts a constant pressure on the pistons 60 independent of their positions. All of the pistons together determine the position of piston 63 and thus the control of the warp let-off through gearing 13. The warp tension can be varied by changing the pressure p in cylinder 34.

The illustration at FIG. 5 is purely schematic; therefore it is not to be assumed that piston 63 necessarily is located approximately level with the pistons 69. As is obvious to one skilled in the art, the latter along with their portion of the hydraulic chamber can be mounted on a support having the same function and approximately the same location as support 29.

Obviously, in the form of FIG. 5 weights could be substituted for the fluid cylinder 34 and the position of the weights sensed.

I claim:

1. In a a travelling-wave sheeding loom employing heddle frames, the combination comprising a wrap tension equalization mechanism, comprising a first spaced individual means for each heddle frame width section for supporting and tensioning the wrap yarn associated with said width, said first means being located upstream of the heddle frames, a sec-0nd means, cooperating with each of said first means, responsive to changes in the warp tension at any of said first means for substantially equalizing the warp tension at a neighboring first means, each of said first means comprising a member mounted free to pivot in a plane substantially parallel to the warp movement under influence of the warp tension, the pivoting of said first means in the direction of movement of the warp tending to reduce the tension and in the opposite direction tending to increase the tension, said second means comprising individual first members movable back and forth in the direction of the warp for contacting each of said first means for supporting it against the force of the warp tension, said first members defining a plane. individual third means associated with each of said first members and individual fourth means located between each first member and said second means including a tensed fiexible means passing under each of said third means and over each of said fourth means to describe a serpentine path lying in a plane substantially parallel to said plane of said first members, whereby the tension in said flexible means exerts on each of said third means an equal force equal and opposite to that of the warp tension on each of said first means.

2. The combination according to claim 1 wherein said third and fourth means are wheels having a central opening lying substantially in a common plane parallel to said plane of the first members including a support extending transversely to the warp; a first pin for each of said fourth means mounted on said support and located in said opening for permitting the associated wheel to roll and slide over the lateral surface of the pin and a second pin for each of said third means, mounted on individual ones of said first members and located in said opening, for permitting the associated wheel to roll and slide over the lateral surface of the pin.

3. The combination according to claim 2, wherein said force exerted by said flexible means on said third means of a first member at an edge of the fabric woven is less than that exerted on the other of said third means.

4. The combination according to claim 3 wherein the contact between said flexible means is nearer said first means for said fourth means than for said third means and nearer for said third means associated with a first member at an edge of the fabric than for those third means associated with the other of said first members.

5. The combination according to claim 4, wherein said flexible means runs towards and from said third means of a first member at an edge of the fabric at an acute angle to the direction in which said member moves and runs towards and from said third means of the other of said first member substantially parallel to the direction in which said members move.

6. In a travellingwave shedding loom having at least three heddle frames arranged side by side moved one after another, a warp beam having several groups of warp threads, each group being associated with a heddle frame, the combination comprising a warp thread tension device for each group of warp threads, comprising each a first and a second turn off wheel, a pivoted lever on which said wheels are mounted, a tension equalization device for the mutual equalization of the thread tensions of all said warp thread groups, comprising members engaging said levers and means for automatically distributing and exerting during loom operation an equal force to all of said members for the mutual equalization of the thread tensions.

7. The combination according to claim 6 wherein said levers pivot in a plane substantially parallel to the warp movement under the influence of warp tension, the pivoting of said levers in the direction of movement of the warp tending to reduce the tension and in the opposite direction tending to increase the tension.

8. The combination according to claim 6 wherein each of said levers supports an upper and a lower cross arm over which the warp passes towards the heddle frames.

9. The combination according to claim 6 including a fifth means cooperating with said second means for bold ing the warp tension substantially at a desired value for all positions of the heddle frames.

10. The combination according to claim 9, wherein said second means includes an individual first member movable back and forth in the direction of the warp for contacting each of said first means for supporting it against the force of the warp tension, said first members defining a plane; in individual third means associated with each of said first members and an individual fourth means located between each first member and wherein said second means further includes flexible means passing under each of said third means and over each of said fourth means to describe a serpentine path lying in a plane substantially parallel to said plane of the first members, said fifth means subjecting said flexible means to a constant tension, whereby said flexible means exerts on each said third means an equal and constant force equal and opposite to that of the warp tension on each of said first means.

11. The combination according to claim 10, wherein said third and fourth mean-s are wheels having a central opening lying substantially in a common plane parallel to said plane of the first members; and including a support extending transversely to the warp; a first pin for each of said fourth means, mounted on said support and located in said opening, for permitting the associated wheel to roll and slide over the lateral surface of the pin; and a sec-ond pin for each of said third means, mounted on individual ones of said first members and located in said opening, for permitting the associated wheel to roll and slide over the lateral surface of the pin.

12. The combination according to claim 11, wherein said force exerted by said flexible means on said third means of a first member at an edge of the fabric woven is less than that exerted on the other of said third means.

13. The combination according to claim 12, wherein the contact between said flexible means is nearer said first means for said fourth means than for said third means and nearer for saidthird means associated with a first member at an edge of the fabric than for those third means associated with the other of said first members.

14. The combination according to claim 13, wherein said flexible means runs towards and from said third means of a first member at an edge of the fabric at an acute angle to the direction in which said member moves and runs towards and from said third means of the other of said first member substantially parallel to the direction in which said members move.

15. The combination according to claim 10, wherein said flexible means has first and second ends and said fifth means includes a fluid piston under an adjustable constant pressure and acting on one end of said flexible means.

16. The combination according to claim 10, wherein said flexible means has first and second ends and said fifth means includes a weight of adjustable size hung from one end of said flexible means.

17. The combination according to claim 6, including an individual first fluid piston acting on each of said first means in a direction to support the latter against the force exerted on it by the warp tension, each said piston being under the same hydraulic pressure; a second piston in hydraulic communication with said first pistons acted upon by an adjustable constant force for causing the hydraulic pressure acting on said first pistons.

18. The combination according to claim 17, including a fluid piston acting on said second piston to produce said force.

19. The combination according to claim 9, wherein the position of said fifth means varies in dependence on the tension exerted on said flexible means; and means responsive to the position of said fifth means for controlling the let-off control gearing of the loom.

References Cited UNITED STATES PATENTS 2,433,190 12/1947 Ancet 139-13 2,679,264 5/1954 Dunod 139--13 2,988,113 6/1961 Smiley 13997 3,147,776 9/1964 Hofmann 139-1 14 FOREIGN PATENTS 240,564 8/ 1962 Australia. 559,047 9/ 1932 Germany.

OTHER REFERENCES Haberhauer: German App. No. 1,072,659, Pub. 1960.

HENRY s. JAUDON, Primary Examiner.

Images