GB2118979A

GB2118979A - Improvements in or relating to fabric winding-on mechanisms for knitting machines

Info

Publication number: GB2118979A
Application number: GB08310434A
Authority: GB
Inventors: Peter Michael Findlay
Original assignee: Camber International England Ltd
Current assignee: Camber International England Ltd
Priority date: 1982-04-20
Filing date: 1983-04-18
Publication date: 1983-11-09
Also published as: GB8310434D0

Abstract

A fabric winding-on mechanism for a knitting machine includes guide means (16) to receive the fabric (F), and a bale-forming roller (4), said roller being driven by a variable torque motor (8), said motor having low torque characteristics at relatively high rotational wind-on speeds of the said roller (4) and high torque characteristics at relatively low rotational wind-on speeds thereof, there being provided sensing means (20) capable of following the progressive increase in the diameter of a bale formed on the roller and control means (28) capable of continuously varying the torque characteristics of the motor (8) in accord with a signal produced by the sensing means and in response to incipient changes in the tension in the fabric (F). <IMAGE>

Description

SPECIFICATION Improvements in or relating to fabric windingon mechanisms for knitting machines The invention is concerned with improvements in or relating to fabric winding-on mechanisms for knitting machines.

When a fabric is produced for example by a circular knitting machine, the fabric as it is knitted is conventionally drawn downwardly from the knitting locality of the machine by the use of driven rollers and is then wound onto a roller to form a bale. However, in order to ensure that the quality of the fabric is not adversely affected during this winding-on operation, it is desirable to maintain the fabric under a constant tension as it leaves the knitting locality, and to form it into turns on the bale under the same conditions of tension when the bale is small in diameter as when, at the end of the winding-on operation, the bale is many times greater in diameter, taking account of variations in the rate of operation of the knitting machine.

Many arrangements have been proposed in attempts to achieve this purpose, but these are usually of complicated mechanical construction, involving complex gearing arrangements.

Moreover, they have met with only limited success. It is an object of the present invention to provide a winding-on mechanism which is efficient in operation and simple in construction.

The invention provides a fabric winding-on mechanism for use in a knitting machine comprising guide means to receive the fabric, and a bale-forming roller, said roller being driven by a variable torque motor, the motor having low torque characteristics at relatively high rotational wind-on speeds of said roller and high torque characteristics at relatively low rotational wind-on speeds thereof, there being provided sensing means capable of following the progressive increase in the diameter of a bale formed on the roller and control means capable of continuously varying the torque characteristics of the motor in accord with a signal produced by the sensing means and in response to incipient changes in the tension in the fabric.

Conveniently, the guide means comprises two or more rods past which the fabric travels and which are supported in a framework beneath the knitting locality. The rods may be fixed, that is non-rotatable, or may be driven, or may be free to rotate with the passage of fabric therepast. The framework may also support the winding-on mechanism and may be rotatable about a substantially vertical axis with the operation of the circular knitting machine.

In an example of the invention to be described below, the sensing means comprises a movable bar resting upon the bale under gravity and mounted to permit the bar to move outwardly of the fabric bale as the diameter of the bale increases. The angular amount of said pivotal movement is sensed, amplified as necessary, and caused to operate the control means to vary the operation of the motor so that the speed of rotation of the roller is reduced progressively to maintain the peripheral speed of the bale at the same or substantially the same rate and thus the tension in the fabric at a substantially constant level. However, changes occur in the rate of production of the fabric, notably a slowing or cessation of fabric production due to the need to inspect or correct faults in the knitting operation.

This would initially result in an increase in tension in the fabric about to be wound on to the bale, but it is arranged that any incipient increase in tension is sufficient to prevent the torque motor from maintaining the speed of rotation of the bale roller, which will slow down, thereby returning the tension in the fabric to the desired level.

There will now be described one example of apparatus according to the invention. It will be understood that the description, which is to be read with reference to the drawings is given by way of example only and not by way of limitation.

In the drawings: Figure 1 is an end view of the apparatus with parts removed for clarity; and Figure 2 is a side view thereof, partly in crosssection.

The Figures show an apparatus comprising a framework incorporating two end panels 2, and a bale roller 4 mounted therebetween for rotation about a horizontal axis. The apparatus is mounted for bodily rotation about a central vertical axis in synchronisation with the operation of a circular knitting machine (not shown) below which it is mounted.

The bale roller 4 is driven through a drive belt 6 from a torque motor 8 having a gear mechanism 10, mounted upon one of the end panels 2. In the present example, the torque motor has a voltage range of between 45 and 8 volts, with operating speeds between approximately 55 to 1100 rpm.

The total gear ratio is 108:1. Power is supplied to the motor through a slip ring arrangement indicated at 12.

Fabric F is produced in the conventional manner at the annular operating locality of the knitting machine and comprises a sleeve which is to be flattened into a double-thickness length prior to being wound onto the roller 4. To achieve this, the fabric is drawn over a tensioning and spreading device of conventional design (not shown) and is received in flat form by guide means comprising two pairs of rods 14, 16, secured between brackets 18 on the end panels 2. The upper pair of rods, 14, contact the sleeve of fabric initially and are spaced apart more widely than the lower pair 1 6. The fabric is thus formed into a double-thickness length of a predetermined width which is maintained, because of its contact with the rods 14, 1 6, and because of the conditions of constant tension which use of the invention maintains.

Assuming that the rate of production of the fabric from the knitting machine is constant, in order to maintain conditions of constant tension in the fabric throughout the formation of a bale B, it is necessary to decrease the speed of rotation of the roller 4 at a rate relative to the increasing diameter of the bale so as to maintain the peripheral speed of the bale at a constant level so that the outermost turn of fabric at any moment in the formation of the bale is at the same tension as its underlying turns.

In the present example, the sensing means to detect the increase in the diameter of the bale is provided by a bar 20 resting upon the peripheral surface of the bale and comprising, as shown in Figure 2, a substantially U-shaped member mounted for pivotal movement about a horizontal axis so that the bar is capable of movement between the position 20' in which the bale diameter is at its smallest (B') and the position 20" in which the bale is completed, B" (Figure 1.).

For convenience in the present example, the bar 20 is shown mounted upon a first one of the pair of rods 16 between which the sleeve of fabric F is received.

Thus while the other rod 16 is securely mounted in the brackets 18, the first rod is capable of limited pivotal movement in response to movement of the bar 20. One end of the first rod 16 is mounted with respect to an arrangement of gear wheels (22, 24) which amplify the pivotal movement of the rod 16 (about 50 ) so that a shaft 26 connected to a control box 28 rotates through at least 1 800 during the build-up of a bale B.

This movement is received by the control box 28 and operates a variable control device progressively to vary the operating voltage of the torque motor 8, so that the rotation of the roller 4 is decelerated as the diameter of the bale increases. Thus the peripheral speed of the bale is maintained constant or substantially constant while the knitting machine is operating at a constant knitting rate. However, there may be variations in the knitting rate and these are taken into account by the torque motor, which under conditions of high torque (raised tension) produces a lower speed of rotation in the bale roller and in the event of low torque conditions (lowered tension in the fabric) produces a higher rotation speed in the roller. Thus the invention ensures that the fabric is would onto the bale at a constant tension.

Various modifications may be made within the scope of the invention as defined by the following

Claims

claims. CLAIMS

1. A fabric winding-on mechanism for use in a knitting machine comprising guide means to receive the fabric, and a bale-forming roller, said roller being driven by a variable torque motor, the motor having low torque characteristics at relatively high rotational wind-on speeds of said roller and high torque characteristics atrelatively low rotational wind-on speeds thereof, there being provided sensing means capable of following the progressive increase in the diameter of a bale formed on the roller and control means capable of continuously varying the torque characteristics of the motor in accord with a signal produced by the sensing means and in response to incipient changes in the tension in the fabric.

2. A mechanism as claimed in claim 1 wherein the sensing means comprises a movable bar resting upon the bale under gravity and mounted to permit the bar to move outwardly of the fabric bale as the diameter of the bale increases.

3. A mechanism as claimed in claim 2, wherein the control means is operated in response to the amount of said movement to vary the operation of the motor so that the speed of rotation of the roller is reduced progressively to maintain the peripheral speed of the bale at the same or substantially the same rate and thus the tension in the fabric at a substantially constant level.

4. A mechanism as claimed in either one of claims 2 and 3 wherein the guide means comprises two or more rods past which the fabric travels, one of said rods being mounted for limited rotational movement, the moveable bar being mounted upon said rod in order to partake of its outward movement in a pivotal manner about the axis of said rod.

5. A mechanism as claimed in claim 4 wherein a further one of said rods is fixedly secured in a framework of the machine.

6. A mechanism as claimed in claim 1, wherein the guide means comprises at least two rods past which the fabric travels, at least one of said rods being fully rotatable.

7. A mechanism as claimed in claim 6, wherein said fully rotatable rod(s) is/are driven by suitable drive means.

8. A fabric wind-on mechanism for use in a knitting machine, constructed and arranged substantially as hereinbefore described with reference to and as shown in the drawings.