GB2231341A

GB2231341A - Yarn stop-motion device

Info

Publication number: GB2231341A
Application number: GB8910606A
Authority: GB
Inventors: Donald Stinson
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-05-09
Filing date: 1989-05-09
Publication date: 1990-11-14
Also published as: GB8910606D0

Abstract

A stop motion device for detecting the presence of a moving yarn or yarns e.g. in a knitting machine has a movable guide 16 displaceable on a lever 12 between a raised position in which yarn is stationary ready for use and a generally horizontal position in which moving yarn is fed to a yarn-consuming machine. The level 12 is spring-biased towards the raised position, the tension of feeding yarn displacing the lever to the horizontal position against the spring-biasing. A switch is actuated by displacement of the guide 12 from the horizontal position, to stop the yarn-consuming machine. A further switch in series may allow the stop motion to function only at selected periods during the machine cycle, eg when all of a plurality of yarns are being fed simultaneously. <IMAGE>

Description

Stop Motion Device The present invention relates to a stop motion device for a yarn-consuming machine particularly, but not exclusively, a knitting machine.

The term stop motion as applied to a knitting machine relates to an electrical or mechanical device designed automatically to arrest machine operation upon the occurrence of a mechanical fault such as a yarn break, press off or the like. Typically a stop motion device is placed close to the yarn supply point so that in the event of yarn failure as much time as possible is allowed for stopping the machine.

In one known stop motion device, after passing through a yarn tensioner, yarn passes over a lightly-loaded lever which will fall in the event of absence of yarn, or if the input tension is too light to hold the lever in a vertical position. Fall of the lever completes an electrical or mechanical circuit which energises a solenoid (or a lever) to operate a switch to stop the machine drive. If there is a snatch from the yarn cone or the input tension becomes excessive for any reason, such as blocked or damaged guides, the lever is pulled down which completes the circuit to operate the solenoid. The electrical power supply is passed through a transformer so that the stop motion device operates on a low voltage, typically 24 volts, and hence is not dangerous.

A problem associated with known stop motion devices is that although they detect the presence of yarn they do not detect whether or not that yarn is moving. Hence, should the passage of the yarn from the cone to the knitting needles be arrested for any reason, the stop motion device does not operate. This creates special difficulty in the knitting of hosiery, particularly when two or more yarns are fed through a common feeder. In this instance typically four yarns are fed to the knitting needles simultaneously when the leg and/or foot portions are knitted. Should one (or more) of the four yarns be arrested, the knitting machine continues to knit but produces a substandard article which is visibly "stripped".

On the older type of machine, which perhaps required 3 mins to knit a sock, there was no real difficulty in that the fault would be noticed by the machine operator and corrected. More modern machines however knit a sock in about 40 seconds so that by the time the operator notices the fault 4 or 5 substandard socks could have been knitted.

An object of the present invention is to provide a stop motion device for detecting the presence of a moving yarn.

In accordance with the present invention there is provided a stop motion device for detecting the presence of a moving yarn comprising a movable yarn guide displaceable between a first position in which yarn is held ready for use and a second position in which yarn is fed passed the movable guide to a yarn-consuming machine, means for loading'the guide towards said first position, the tension of feeding yarn displacing the guide from said first to said second position, and a control circuit including a switch, actuation of which is arranged to stop the yarn-consuming machine in response to displacement of the movable guide from said second to said first position.

The movable guide may be a poteye connected to one end of a pivotable lever such as the limb of a microswitch or a make-and-break switch. In a preferred embodiment of the invention, when the guide is in said second position it lies horizontally or substantially so, a force such as a spring or a solenoid normally loading the lever away from said second position into the first position above said second position. Yarn is led upwardly through the poteye and then downwardly towards the yarn-consuming machine.

Hence, when yarn is present at the poteye, the lever occupies the first position but when yarn is being fed through the poteye, the yarn tension is sufficient to displace the lever downwardly into the second position.

Conveniently a fixed guide, such as a poteye, is provided on either side of the movable guide, conveniently in a horizontal plane beneath the movable guide. In this way, when the movable guide lies in the second position, a generally horizontal yarn path is facilitated.

If desired, the stop motion device may be functional for only a part of the machine cycle. For example, on a hosiery knitting machine where say four yarns are fed through a common feeder, the stop motion device may be arranged to function only at the or each period when all four yarns should be feeding yarn to the needles to knit for example the foot portion. Conveniently this is achieved by connecting a further switch in electrical series relationship with the switch of the stop motion device, the further switch being closed only for selected periods when all four yarns should be feeding.

If desired, the stop motion device of the invention may be used in combination with other types of stop motion device which are used in their normal manner to detect other known mechanical faults.

The present invention is further described hereinafter, by way of example, with reference to the accompanying drawing, the single figure of which illustrates, in diagrammatic form, a stop motion device according to the invention.

The stop motion device illustrated in Figure 1 is in an in-use position in which yarn is being fed from a yarn cone 10 to a yarn-consuming machine (not shown). The device consists of a lever 12 pivotted at 14 and occupying a generally horizontal position. The free end of the lever carries a poteye 16 through which the yarn passes, upwardly from the yarn cone and downwardly towards the yarn-consuming machine. The generally horizontal yarn path is facilitated by two fixed poteyes 18, 20 lying generally horizontally below the poteye 16, yarn passing upwardly through the poteye 20 and downwardly through the poteye 18.

The lever 12 is biased upwardly (diagrammatically anti-clockwise as viewed) towards a "ready for use" position (not shown). Biasing is achieved either by a separate spring or by utilizing the internal spring 22 of a solenoid (not shown). When the yarn is present in the yarn path but in a stationary condition, the lever 12 is biased towards the "ready for use" position. However, as the yarn commences to move and tension builds up in the yarn, the lever 12 becomes loaded and is pivotted clockwise against the resilient loading to occupy the position illustrated.

Should, for example, the yarn cease moving for any reason, the spring returns the lever 12 to the "ready for use" position.

Claims

Claims

1A stop motion device for detecting the presence of a moving yarn comprising a movable yarn guide displaceable between a first position in which yarn is held ready for use and a second position in which yarn is fed past the movable guide to a yarn-consuming machine, means for loading the guide towards said first position, the tension of feeding yarn displacing the guide from said first to said second position, and a control circuit including a switch, actuation of which is arranged to stop the yarn-consuming machine in response to displacement of the movable guide from said second to said first position.
2 A stop motion device as claimed in claim 1 in which the movable guide comprises a poteye connected to one end of a pivotable lever such as the limb of a microswitch or a make and-break switch.
3 A stop motion device as claimed in claim 2 in which, when the guide is in said second position, it lies horizontally or substantially so, a force such as a spring or a solenoid normally loading the lever away from said second position into the first position above said second position.
4 A stop motion device as claimed in claim 2 or 3 in which yarn is led upwardly, through the poteye and then downwardly towards the yarn-consuming machine, so that when yarn is present at the poteye, the lever occupies the first position but when yarn is being fed through the poteye, the yarn tension is sufficient to displace the lever downwardly into the second position.
5 A stop motion device as claimed in claim 3 or 4 in which a fixed guide, such as a poteye, is provided on either side of the movable guide, conveniently in a horizontal plane beneath the movable guide, so that when the movable guide lies in the second position, a generally horizontal yarn path is facilitated.
6 A stop motion device as claimed in any one of claims 1 to

5 in which the stop motion device is functional for only a part of the cycle of the yarn-consuming machine.
7 A stop motion device as claimed in claim 6 in which when a plurality of yarns are fed through a common feeder, the stop motion device functions only at the or each period when all yarns should be feeding yarn to the yarn-consuming machine.
8 A stop motion device as claimed in claim 7 in which a further switch is connected in electrical series relationship with the switch of the stop motion device, the further switch being closed only for selected periods when the plurality of yarns should be feeding.
9 A stop motion device as claimed in any one of the preceding claims when used in combination with other types of stop motion device which are used in their normal manner to detect other known mechanical faults.
10 A stop motion device substantially as herein described with reference to and as illustrated in the accompanying drawing.