US3555854A - Warp knitting machine - Google Patents

Abstract

THE FRONT AND REAR THREAD TENSION "SEESAWS," WHICH OPERATE WITH THE RESPECTIVE FRONT AND REAR SETS OF WARP THREADS OF A TWO-NEEDLE BED RASCHEL KNITTING MACHINE, ARE CONNECTED TOGETHER BY A TENSION SPRING SO THAT UNIFORM TENSION IS MAINTAINED ON EACH SET OF WARP THREADS DURING SWINGING MOVEMENTS OF THE THREAD GUIDES ACROSS THE NEEDLE BEDS. THIS TENSION SPRING CONNECTION PROVIDES TENSION COMPENSATION BETWEEN THE FRONT AND REAR SETS OF WARP THREADS BY CREATING A CONSTANT EXCHANGE OF KINETIC ENERGY BETWEEN THE RESPECTIVE TENSION SEESAWS WHILE THE LOADING OF THE SPRING REMAINS SUBSTANTIALLY UNCHANGED.

Description

Jam 19 1971 I E WARP KNITTING MACHINE Filed May 5, 1969 INVENTOR. v MAmus ANTO1NE- PERRHi-R ATTORNEYS United States Patent 3,555,854 WARP KNITTING MACHINE Marius Antoine Perrier, Lyon, France, assignor to Jean Gusken, Viersen-Dulken, Germany Filed May 5, 1969, Ser. No. 821,887 Claims priority, application Germany, May 3, 1968, 1,760,324 Int. Cl. D04b 23/02 US. C]. 66-87 6 Claims ABSTRACT OF THE DISCLOSURE The front and rear thread tension seesaws, which operate with the respective front and rear sets of warp threads of a two-needle bed Raschel knitting machine, are connected together by a tension spring so that uniform tension is maintained on each set of warp threads during swinging movements of the thread guides across the needle beds. This tension spring connection provides tension compensation between the front and rear sets of warp threads by creating a constant exchange of kinetic energy between the respective tension seesaws while the loading of the spring remains substantially unchanged.

The invention relates to an arrangement for maintaining uniform thread tension on two needle bed fiat warp knitting machines, especially Raschel machines, provided with at least two sets of warp threads guided to the thread guides over spring weighted seesaws," and passing downwardly on different sides of the thread-guide support shaft.

Incorporating of yarn tension seesaws in the feeding line of the sets of threads from the front and rear warp beams to the needles of the front and rear beds becomes necessary because of the steadily changing yarn requirements during the lay or shogging movements of the thread guides and the insertion of the warp threads into the knitted fabric. The thread tension seesaws, on which the sets of threads get an artificial elongation by each being directed under and over two thread tension rods or tubes, are steadily compensating for the changing thread requirements because the tension rods are pivotally mounted and are acting against spring pressure. The seesaws make oscillating swinging movements through a limited angle under the counteracting loads of the thread tension on one side and the spring tension on the other side. If the limits of this angle are exceeded to one or the other side, the speed of the warp thread feeding regulator has to be adjusted accordingly.

In certain applications the oscillating system, consisting of the mass of the thread tension seesaw and the set of warp threads on one side and the spring acting on the seesaw on the other side, can have an insufficient dampening.

For instance, when knitting fine gauge hosiery type fabrics from very fine thread or yarn on Raschel machines, it has been found that insufiicient dampening of the oscillating movements produces courses of stitches which are uneven in their structure, which, of course, is not desirable. On the other hand, the dampening cannot be artificially increased due to the required easy movement of the yarn tension seesaws.

An object of the present invention is therefore to avoid the disadvantage of an uneven stitch structure under all conditions and still maintain an easy mobility of the yarn tension seesaws.

According to the invention, this problem is solved by providing a tension spring connection between the yarn tension seesaws of the two sets of warp yarns which pass downwardly on opposite sides of the thread guide support shaft and whose warp threads are inserted into the knitted fabric with the same average yarn consumption.

The invention takes advantage of the condition that the oscillating movement of the guide supports carrying the yarn guides act in opposing directions on the two sets of warp yarns, passing by on different sides of the yarn guide support shaft. While the pull and the length requirements increase on one set of yarns, the pull and length requirements decrease on the other set of yarns and vice versa. This has the result that the respective yarn tension seesaws make counteracting movements to compensate for the lengthening or shortening of the sets of yarn so that there are at least overlapping motion components counteracting the oscillating movements. In known types of yarn tension compensation devices, the seesaw springs are suspended from the frame and have to continuously follow these movements so that their respective motion components and their potential energy changes continuously during this process. However, the spring loading of the yarn tension seesaws against each other, according to the invention, creates a system of two functionally connected masses having a constant exchange of kinetic energy between them, while the springitself changes its potential energy only a little. Through this arrangement, as practical experience has shown, the oscillating movements of the yarn tension seesaws are considerably smoother and a substantially more even stitch structure appears.

Elaborating on the invention in an advantageous way, a tension spring is suspended between two levers which are in turn connected to the two yarn tension seesaws to thereby serve for the mutual spring loading of the two seesaws. The use of levers instead of a leather tape slung around a pulley has the advantage that pre-tension force and tension characteristics of the spring can be changed relatively easy and can be adapted to the operating requirements. To this end, the effective length of the levers can be adjustable and also the angles between the levers so that the operation of the yarn tension seesaws can be variable.

When the yarn tension control of the present invention is utilized on a machine provided with positive warp yarn feed, the two warp beams belonging to the mutually spring loaded yarn tension seesaws can be driven by means of a joint yarn tension controlled and adjustable special gearing, whose adjustment can be regulated from one of the two yarn tension seesaws. This makes a second special gearing unnecessary and assures at the same time that the oscillation ranges of the two yarn tension seesaws are always equal and the spring acting between the seesaws essentially maintains its length and tension.

The invention is explained in more detail in connection with the drawing which is a schematic perspective view showing the essential parts of a two-needle bed Raschel machine.

A machine frame, not shown, supports two turning front and rear warp beams 1 and 2, from which sets of warp yarns 3 and 4, indicated by one thread each, are drawn and pass over tension seesaws 5 and 6. The front and rear sets of warp yarns 3, 4 are fed to the needle beds by yarn guides 7 and 8 which are carried on guide supports 11, equipped with for instance six guide rods and pivotally mounted on a guide support shaft 9. Swinging oscillation is imparted to the yarn guides 7 and 8 in the conventional manner by a connector rod .10. By swinging the guide supports '11 and by the longitudinal movement of the guide rods in a certain rhythm, timed to the alternate raising and lowering of front end rear latch needles 12 and 13, stitches are alternatively made on the front and back rows of the latch needles, as it is commonly known.

In order to provide the yarn length necessary for forming the courses of stitches, the warp beams 1 and 2 are positively driven from the main shaft 14 and through a special gearing 15. The special gearing 15 is in the form of a variable speed drive which is driven from the main shaft 14 by means of a chain drive 16. The output drive shaft 17 of the variable speed gearing =15 drives a transmitting shaft 21 through a set of change gears 18, 19, and 20. A chain sprocket 22 is fixed on the shaft 21 and drives a chain 23 which passes over a sprocket 25 fixed on the end of a shaft 24 on the warp beam 1. The end of the shaft 24 is also provided with a gear 26 meshing with an equally sized gear 27 fixed on a reversing shaft 28. The drive of this reversing shaft is connected to the warp beam 2 through a set of equally sized chain sprockets 29, 30 over which a sprocket chain 31 passes.

Because of the equal dimensions of the pair of gears 26, 27 and the pair of chain sprockets 29, 30, the rotating speeds of the warp beams 1, 2, running in opposite directions, are always the same. The yarn tension seesaws 5 and 6 are located on and fixedly connected to shafts 32 and 33. Collars 36 and 37 are provided with respective upstanding levers 34 and 35, and the collars are locked to the shafts with screws 38 and 39 so that their circumferential positions can be adjusted. The levers 34 and are provided with respective spring supports 42 and 43 which are fastened to them with screws and 41 in a similar way. Between these supports the tension spring 44 is suspended, 'which gives the yarn tension seesaws 5 and 6 the back motion momentum acting against the pull of the sets of warp yarns 3 and 4.

Locked to the seesaw shaft 33 are further, at an angle to each other, two cam levers 45 and 46, acting on limit switches 47 and 48 which are solidly attached to the frame. From the limit switches 47 and 48, wires 49 and 50 go to a time relay 51 which is connected to the power supply 52 of a reversible control motor 53 for the operating variable speed drive 15. Two worm gear drives 54 and 55 with a connecting shaft 56 create a considerable reduction between the speed of a driving shaft 57 of the control motor 53 and an adjusting shaft 58 of the variable speed drive 15.

The angle formed by the cam levers 45 and 46 is chosen large enough so that the levers can oscillate freely between the limit switches with a normal oscillating movement of the seesaw 6, which is, due to the equal yarn consumption and the equal yarn feed, the same as that of seesaw 5. As long as the yard feed corresponds to the yarn consumption, this range of oscillation is maintained. But, if the rate of yarn feed deviates from the rate of yarn consumption, which is for instance the usual case when the effective diameter of the warp beam is reduced, then one of the limit switches 47, 48 is actuated by the corresponding cam lever 45, 46, energizing the control motor 53 through the time relay 51 which maintains the impulse for a time that is adjustable by a regulating knob 59. The amount of rotation of the control motor 53 is such that the yarn feeding speed is adjusted accordingly by adjustment of the variable speed drive 15.

AS shown in the drawing, the warp threads 3 and 4 pass by on different sides of the guide support shaft 9 and to the respective yarn guides 7 and 8. During an oscillation movement of the guile support 11 toward the rear, to the left in the drawing, a pulling force is exerted on the front set of warp threads 3 which turns the yarn tension seesaw 5 in a clockwise direction. At the same time, the pull on the rear set of warp threads 4 is reduced, whereby the yarn tension seesaw 6, actuated by the tension spring 44- also turns in a clockwise direction. When the guide supports 11 and the yarn guides swing toward the front, to the right in the drawing, the yarn tension seesaws 5 and 6 are turned accordingly in an opposite direction. By swinging the yarn tension seesaws 5 and 6 each in the same direction, the length of the tension spring 44 remains essentially the same and its potential energy practically does not change. The result of this is a consider- 4 ably smoother oscillating movement of the yarn tension seesaws 5 and 6 which produces a considerably more even stitch structure in the knitted fabric.

In the drawing and specification there has been set forth a preferred embodiment of the invention and although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation. I claim: 1. A yarn tension control apparatus for two-needle bed fiat warp knitting machines, especially Raschel machines, having at least front and rear sets of warp yarns, yarn guides swinging back and forth across said needle beds, and a guide support shaft supporting said yarn guides, said yarn tension control apparatus comprising (a) front and rear yarn tension seesaws each including spaced-apart tension rods with the respective front and rear sets of warp yarns passing under and over said tension rods and urging said tension seesaws in one direction, and (b) common tension spring means connecting said front and rear tension seesaws and urging the same in the other direction and against the pull of the sets of warp yarns. 2. A yarn tension control apparatus according to claim- 1 wherein said common tension spring means comprises a single tension spring, and including a pair of upstanding levers connected at their lower ends to said front and rear tension seesaws, and means for connecting opposite ends of said tension spring to said upstanding levers of said corresponding yarn tension seesaws.

3. A yarn tension control apparatus according to claim 2 wherein said spring connecting means is supported for longitudinal adjustment on said upstanding levers to thereby vary the eifective length of said levers.

4. A yarn tension control apparatus according to claim 2 including means connecting the lower ends of said upstanding levers to said corresponding tension seesaws for angular adjustment therewith.

5. A yarn tension control apparatus according to claim 1 wherein said knitting machine includes front and rear warp beams, and positive warp yarn feeding means for normally rotating said warp beams at a given rate, and wherein said tension control apparatus includes control means operatively associated with one of said tension seesaws for varying the speed of rotation of said warp beams.

6. A yarn tension control apparatus according to claim 5 wherein said positive warp yarn feeding means includes a variable speed drive unit having an output drive shaft drivingly connected to said warp beams, and wherein said control means includes a pair of control levers connected to one of said tension seesaws, a pair of limit switches operable by said corresponding control levers in response to abnormal movement of said tension seesaw, a control motor drivingly connected to said variable speed drive unit and operable to change the rotational speed of said warp beams, and a time delay relay unit interposed between said limit switches and said control motor whereby operation of said control motor is dependent upon actuation of one of said limit switches for a predetermined period.

References Cited UNITED STATES PATENTS 1,318,625 10/ 1919 Walther 6687 2,521,218 9/1950 Hepp 6686 2,598,540 5/1952 Henry 66--86 FOREIGN PATENTS 134,360 11/1919 Great Britain 6687 6403020 5 1965 Netherlands 6686 ROBERT R. MACKEY, Primary Examiner U.S. Cl. X.R.

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