GB2109825A - Method and apparatus for feeding thread into a loop-forming system of a knitting machine - Google Patents

Abstract

A method and apparatus according to the invention are used in circular knitting machines for knitting piecemeal and web products. In accordance with the method, from a thread A are formed turns B extending around a thread supply roll 3 which cooperates with a drive belt 2, and around a cantilever bar 4. At least a part of the thread turns are capable of extending both beneath and outside the belt 2. When the turns are outside the belt 2, the thread tension is caused to relax by bringing these thread turns into engagement with an auxiliary thread supply roll 5 which is caused to rotate at a speed greater than the rotary speed of the main thread supply roll 3. This makes it possible to control either thread tension or its feed rate at a pre-set point of knitting cycle of a product. <IMAGE>

Description

SPECIFICATION Method and apparatus for feeding thread into a loop-forming system of a knitting machine The invention relates to knitting machines, and more particularly it deals with a method and apparatus for feeding thread into a loop-forming system of such machines. The invention may be preferably used in circular knitting machines and, depending on the type of threading, it may be used in both machines for knitting piecemeal products (swatches, hosiery) and in machines for web knitting.

It is an object of the invention to provide a method and apparatus for feeding thread into a loop-forming system of a knitting machine which enable working various portions of products with different loop length by automatically controlling the thread speed or the thread tension.

According to the invention, a method for feeding thread into a loop-forming system of a knitting machine comprises: forming from a thread fed through thread guide eyes turns which extend around a thread supply roll cooperating with a drive belt and around a cantilever bar; at least a part of the thread turns being capable of extending both beneath and outside the belt; the thread tensioning being caused to relax when the thread turns are outside the belt by bringing these thread turns into engagement with a cylindrical surface which is caused to rotate at a speed greater than the rotary speed of the thread supply roll.An apparatus for carrying out the method comprises: a thread supply roll surrounded by a drive belt; inlet and outlet thread guide eyes; a cantilever bar provided laterally with respect to said thread supply roll, thread turns extending around the cantilever bar and the thread supply roll and being capable of extending both beneath and outside the belt; an auxiliary driven thread supply roll which is mounted for rotation at a speed which is greater than the rotary speed of the main thread supply roll and coaxially therewith so that one roll is partly received in the other; said cantilever bar extending along both thread supply rolls; at least one said thread guide eyes being installed opposite to the auxiliary thread supply roll.

The provision of the auxiliary thread supply roll which is caused to rotate at a speed which is greater than the speed of the main roll makes it possible to reduce and stabilize the thread tension at the outlet of the apparatus when the turns (or a part thereof) are outside the belt and to work portions of a knitted product with a different (greater) length of loops compared to a portion which is worked when the turns are beneath the belt.

In addition, the arrangement of a part of turns on the auxiliary thread supply roll, while the other turns are beneath the belt, makes it possible to ensure a pre-set quantity of thread being supplied at high accuracy.

The cantilever bar is preferably provided with a thread guide which is disposed opposite to the zone where one thread supply roll is received in the other. This facility enables the accomodation of thread turns on both rolls thereby ensuring high accuracy of the positive thread feed (at a pre-set speed).

In order to simplify the automatic control of thread supply conditions, one of the thread supply rolls may be provided with a shoulder located in the zone where one roll is received in the other.

In order to provide for the transfer of thread turns from the main thread supply roll to the auxiliary thread supply roll, at least one of the thread guide eyes is mounted for movement along the thread supply rolls by means of any known per se mechanism.

According to the invention, the main and auxiliary thread supply rolls may have a common drive and may be coupled to one another by means of a gearing; alternatively the auxiliary thread supply roll may have an individual drive.

Therefore, the apparatus according to the invention makes it possible to enlarge the field of application of knitting machines producing intricate products with portions differring in the loop length, the working of basic portions with a constant loop length being effected by controlling the thread supply rate and the working of remaining portions of a product being effected by controlling the thread tension. Moreover, the apparatus according to the invention makes it possible to change thread supply functions automatically depending on what portion of a product is worked and also to obtain higher accuracy of the control of quantity of thread being fed by causing a part of turns to extend beneath the belt and the remaining turns to extend on the auxiliary thread supply roll, both tension and speed of the thread being controlled simultaneously.

The invention will now be described in details in the following description of a method and apparatus for feeding thread into a loop-forming system of a knitting machine, with reference to the accompanying drawings, in which: Figures 1 through 6 show various modifications of threading for carrying out a method according to the invention; Figure 7 is a general view of an apparatus in which thread supply rolls are coupled to one another by means of a gearing; Figure 8 is a general view of an apparatus in which thread supply rolls have individual drives; Figure 9 is a plan view of an apparatus shown in Figure 1.

A method for feeding thread into a loopforming system of a knitting machine consists in forming from a thread A (Figures 1 and 2) which is supplied through inlet thread guide eyes 1 turns B extending around a thread supply roll 3 cooperating with a drive belt 2 and around a cantilever bar 4, a part of, or all turns B being capable of extending both beneath and outside the belt. According to the invention, when the turns B are outside the belt, the tension of the thread A is caused to relax by bringing these turns of the thread or a part thereof into engagement with a cylindrical surface C of an auxiliary thread supply roll 5 which is caused to rotate at a speed greater than the rotary speed of the thread supply roll 3.

Figures 1 through 4 show a threading where the thread A first extends around the auxiliary thread supply roll 5 and then around the main thread supply roll 3.

Figure 1 shows an embodiment of the method where all turns B of the thread A extend beneath the belt 2. Subsequently, depending on the portion of a product which is being worked (e.g. in working separating courses between two adjacent products) the turns B of the thread are caused to extend outside the belt 2 (Figure 3) on the auxiliary thread supply roll 5. This threading is preferred in case where the thread tension at the inlet of the apparatus is abnormally high, e.g. in using attached creel bars remote from the knitting zone. In such case, when the turns B of the thread engages the surface of the auxiliary roll 5 rotating a speed which is greater than the speed of the thread A, the thread tension is relaxed and stabilized.

According to the embodiment of the method shown in Figure 2, the method is carried out in such a manner that, e.g. only one turn B of the thread is caused to extend beneath the belt 2 and the remaining turns are caused to extend on the auxiliary roll 5. This threading enables equalization and relaxation of thread tension in the turns when they move around the auxiliary roll 5 owing to its speed being greater than the speed of the moving thread, and also the supply of the thread at a pre-set speed by clamping one turn thereof between the belt 2 and the main roll 3.

As a result a high accuracy of control of quantity of thread being supplied as achieved.

This threading is used, e.g. for working the leg of a hose. For working other portions of hoses and separating courses, an outlet thread guide eye 7 is placed in the position 7' along the roll 3 (Figure 4), one turn of the thread extending outside the belt 2 while remaining on the roll 3, and the remaining turns being caused to extend on the auxiliary roll 5.

Owing to the fact that the number of turns on the auxiliary roll 5 is greater than the number of turns extending on the main thread supply roll 3 and the speed of the auxiliary roll 5 is greater than the thread speed, the thread tension is relaxed and stabilized.

Figures 5 and 6 show a process of threading which is contrary to these described above with reference to Figures 1 through 4, that is the thread A first extends around the main thread supply roll 3 and then around the auxiliary thread supply roll 5, the relaxation and stabilization of the thread tension being effected in the same manner as described with reference to Figures 1 through 4.

An apparatus for feeding thread into a ioopforming system of a knitting machine for carrying out the method according to the invention comprises a casing 6 (Figures 7, 8) in which are installed the main thread supply roll 3 around which extends the drive belt 2, the outlet thread guide eye 1, the outlet thread guide eyes 7, the cantilever bar 4 which may comprise a smooth tapering rod as shown in Figure 1 through 4, 7 or a cylindrical rod as shown in Figures 5, 6 and 8.

Attached to the casing 6 are also a thread tensioning device 8 and known per se devices 9 and 10 (Figure 9) for stopping the knitting machine upon breakage of thread.

The apparatus for feeding thread into a loopforming system of a knitting machine (Figures 7 and 8) also comprises the auxiliary thread supply roll 5 which is mounted for rotation at a speed greater than the speed of rotation of the main thread supply roll 3 and coaxially therewith in such a manner that one roll is partly received in the other. The end face of one of the thread supply rolls which extends outside the other roll is chamfered as shown in Figures 7 and 8, 1 and 3, or it is made without a chamfer as shown in Figures 2 and 4.

The cantilever bar 4 extends laterally of the main and auxiliary rolls 3 and 5 to extend there along in parallel with or at a small angle to their axis.

The cantilever bar 4 and the thread supply rolls 3 and 5 are surrounded by turns of the thread which are capable of extending both beneath the outside the belt 2 so that the turns of the thread move along both thread supply rolls 3 and 5 as shown in Figures 1 through 3. For the turns to move along the main or auxiliary roll, one of the thread guide eyes, e.g. the inlet eye 1 (Figure 7) is installed opposite to the auxiliary thread supply roll 5 and the outlet thread guide eyes 7 are installed on an anchor 11 of a known per se electromagnet 12 so that when the anchor 11 is drawn into the electromagnet 12, the thread guide eyes 7 are caused to move along the thread supply rolls 3 and 5. The electromagnet 12 is secured in the casing 6 by means of a screw 13.

For one roll to be partly received in the other, one of the rolls is made of a diameter larger than the diameter of the other thread supply roll; thus as shown in Figures 1,3,5,6,7 and 8 the main thread supply roll 3 is of a larger diameter than the auxiliary thread supply roll 5, and as shown in Figures 2 and 4 the auxiliary thread supply roll 5 is larger in diameter than the main roll 3.

According to one embodiment of the apparatus, a thread guide 14 (Figures 2,4,8) is provided on the cantilever bar 4 opposite to the zone where one thread supply roll is received in the other thread supply roll, or a shoulder 1 5 (Figures 5, 6) is provided on one of the thread supply rolls 3 or 5 in the zone where one roll is received in the other. In order to prevent the turns from leaving the auxiliary thread supply roll 5, the latter is provided with a collar 1 6.

The main thread supply roll 3 and the auxiliary thread supply roll 5 have a common drive, that is they receive rotary motion from the drive belt 2, the rolls 3 and 5 being coupled to one another by means of a gearing which ensures rotation of the roll 5 at a speed greater than that of the roll 3 and which consists of a stationary gear 1 7 mounted in the casing 6, a planet gear 1 8 having its axle secured to the end face of the main thread supply roll 3, and a gear 19 which is secured to a shaft 20. The shaft 20 is journalled in the casing 6 by means of bearings, and the main thread supply roll 3 is installed on the shaft 20 by means of bearings 21, and the auxiliary thread supply roll 5 is rigidly secured to the shaft 20.

As shown in Figure 8, the auxiliary thread supply roll may have an individual drive such as an electric motor 22 having on its output shaft 23 the auxiliary thread supply roll 5 secured thereto.

The electric motor 22 is secured to the casing 6 by means of a screw 24 and it ensures the rotation of the roll 5 at a speed greater than that of the roll 3.

The apparatus for feeding thread into the loopforming system of a knitting machine is secured to a ring 25 (Figure 9) of the knitting machine by means of an arm 26 (Figures 7 and 8) and by means of a screw 27. Power supply of the electromagnet 12 and of the devices 9 and 10 for stopping the knitting machine is effected through a cable 28. The control of the presence of thread in the apparatus is effected: at the inlet by means of a sensor 29 of the device 9 for stopping the machine and at the outlet by means of a probe 30 of the device 10 for stopping the machine.

The apparatus for feeding thread into a loopforming system of a knitting machine functions in the following manner.

In threading of the apparatus, the thread A is caused to pass through the thread tensioning device 8, the eye of the sensor 29, the inlet thread guide eye 1, the lower outlet thread guide eye 7, then it is wound around the auxiliary thread supply roll 5 (Figure 3) and the cantilever bar 4 in two-four turns B and inserted into the upper thread guide eye 7 so that the probe 30 (Figures 7 and 8) is disposed on top of the outlet run of the thread A.

When the drive of the knitting machine is turned on, both thread supply rolls 3 and 5 (Figure 3) rotate in the same direction, the auxiliary thread supply roll 5 rotating at a speed which is greater than the rotary speed of the main thread supply roll 3, whereby the linear velocity of the auxiliary roll 5 is 2 to 5 times greater than the axial velocity of the thread, the slippage of the thread turns over the surface of the auxiliary roll 5 being ensured by the friction properties of the thread and surface of the auxiliary roll 5 and depending on the thread tension. As the thread tension increases the friction force increases to reduce slippage so that the auxiliary thread supply roll 5 supplies a greater quantity of thread thereby positively controlling the thread tension.This function enables knitting of products having portions with different loop length, e.g. working a starting course of a product, welt, heel, sole and toe of a hose. In knitting, e.g. the leg of a hose, a program control device of the machine actuates the electromagnet 1 2 which causes retraction of the anchor 11 to transfer the turns B (Figure 1) of the thread A to the thread supply roll 3 so as they should extend beneath the drive belt 2. Clamping three-four turns to the surface of the roll 3 simultaneously by the belt 2 prevents the thread from slipping and ensures a positive supply of the thread. The cantilever bar 4 is designed for spreading (separating) the thread turns over the roll surface so as to avoid their tangling and breakage in case one turn comes across another.

The threading shown in Figure 2 is preferred in case where the apparatus is used for positive feeding. This threading ensures minor fluctuations of thread tension at the outlet which is enabled by a stable level of thread tension when it is caused to enter under the belt 2. The thread guide 14 ensures a constant ratio of the numbers of turns on the thread supply rolls 3 and 5. It is preferred to have one turn of thread on the main roll 3 and three-four turns of thread on the auxiliary roll 5.

This facility ensures the possibility of shifting the thread guide eye 7 into the position 7' (Figure 4) for changing the thread supply function by causing only one turn of the thread to move from beneath the belt 2 (without making it necessary to transfer all turns of the thread along both rolls as in Figures 1 and 3). This facilitates the control by displacing the thread guide eyes 7 along the thread supply rolls 3 and 5 and improves the speed of actuation of the apparatus.

Figures 5 and 6 show an embodiment of threading of the apparatus where the thread guide eye 7 is the inlet eye and the thread guide eye 1 is the outlet eye for the thread. The turns B of the thread A are separated by means of the shoulder 1 5 provided on the main thread supply roll 3. In this embodiment the positive thread feeding function (Figure 6) is enabled when the first upstream turn B of the thread A extends beneath the belt 2 on the main roll 3 and remaining turns B (three-four) extend on the auxiliary roll 5. The arrangement of the turns B on the auxiliary roll 5 causes relaxation and stabilization of the thread tension owing to their friction engagement with the surface of the roll 5 and makes it possible to ensure operation of the apparatus in the positive controller function when the eye 7 is shifted to the position 7' (Figure 5).

Claims (9)

Claims

1. A method for feeding thread into a loopforming system of a knitting machine, comprising: forming from a thread supplied through thread guide eyes turns extending around a thread supply roll cooperating with a drive belt and around a cantilever bar; at least a part of the turns being capable of extending both beneath and outside the belt; the thread tension being caused to relax when the thread turns extend outside the belt by bringing these thread turns into engagement with a cylindrical surface which is caused to rotate at a speed greater than the rotary speed of the thread supply roll.

2. An apparatus for carrying out the method of claim 1 , comprising: a thread supply roll surrounded by a drive belt; inlet and outlet thread guide eyes; a cantilever bar provided laterally of said thread supply roll, said thread supply roll and said cantilever roll being surrounded by thread turns which are capable of extending both beneath and outside the belt; an auxiliary thread supply roll which is mounted for rotation at a speed greater than the rotary speed of the main thread supply roll and coaxially therewith so that one roll is partly received in the other; said cantilever bar extending along both thread supply rolls; at least one of said thread guide eyes being provided opposite to the auxiliary thread supply roll.

3. An apparatus as claimed in claim 2, wherein a thread guide is provided on the cantilever bar opposite to the zone where one thread supply roll is recieved in the other.

4. An apparatus as claimed in claim 2, wherein one of siad thread supply rolls is provided with a shoulder opposite to the zone where one thread supply roll is received in the other.

5. An apparatus as claimed in any claim from 2 through 4, wherein at least one of the thread guide eyes is mounted for movement along the thread supply rolls by means of any known per se mechanism.

6. An apparatus as claimed in any claim from 2 through 5, wherein the main and auxiliary thread supply rolls have a common drive and are coupled to one another by means of a gearing.

7. An apparatus as claimed in claims 2 through 5, wherein the auxiliary thread supply roll has an individual drive.

8. A method for feeding thread into a loopforming system of a knitting machine substantially as hereinbefore described with reference to, and as shown in the accompanying drawings.

9. An apparatus for feeding thread into a loopforming system of a knitting machine substantially as hereinabove described with reference to, and as shown in the accompanying drawings.