GB2035388A

GB2035388A - A safety device for knitting machines

Info

Publication number: GB2035388A
Application number: GB7931649A
Authority: GB
Original assignee: Atelier de Construction Steiger SA
Current assignee: Atelier de Construction Steiger SA
Priority date: 1978-09-15
Filing date: 1979-09-12
Publication date: 1980-06-18
Also published as: IT1123160B; GB2035388B; ES484184A1; DE2840338A1; IT7922528V0; BE878342A; FR2436208A1; IT7925729A0

Abstract

A safety device is provided for a flat knitting machine for monitoring the knitting (7) produced on the machine and the needles (6) of the machine comprises a movable sensor (18) which also comprises a thread guide that is mounted to move on a thread guide holder (14). The sensor (18) can be moved out of a normal operating position by striking against an obstacle in its path to actuate a cut-off contact (16, 17) to stop further operation of the machine. <IMAGE>

Description

SPECIFICATION A safety device for knitting machines The present invention relates to a safety device for a knitting machine.

Safety devices for knitting machines are known and include so-called needle monitors for stopping the knitting machine immediately and automatically in the case of bulging of the knitting, which may result for example if a hook of the machine breaks or in the case of a knot in the knitting yarn. These known safety devices operate by use of a scanning needle, which travels directly above the knitting with a carriage of the machine and which is deflected when it strikes against broken or jammed machine needles or locates slipped stitches and thus actuates a switch which stops the knitting machine by way of a relay.

As will be described hereafter with reference to figure 1, which illustrates the known state of the art, the utilisation of a separate scanning needle is only successful where the usual scanning path is free from obstacles. This is not the case for example if so-called insertion thread guides are used and the latter follow the shape of the knitted article. These insertion thread guides are located in the vicinity of the scanning path and thus make the use of a scanning needle impossible. Insertion thread guides are necessary for the production of certain articles, such as for example orthopaedic stockings and socks or the like.

The object of the invention is to provide a safety device which can be used on all flat knitting machines, in particular which can be used when knitting with insertion thread guides.

According to the present invention there is provided a safety device for a flat knitting machine for monitoring the knitting produced on the machine and the needles of the machine, comprising a movable sensor, which can be moved out of a normal operating position by striking against an obstacle to actuate a cut-off contact and thereby stop operation of the knitting machine, the sensor itself comprising a thread guide for the knitting machine and is mounted to move on a thread guide holder.

It can thus be seen that the thread guide arrangement which is movable in itself and consists of the thread guide and thread guide holder, also has the direct function of needle monitor and that when it strikes against the knitting it deflects in a corresponding manner, thus closing the circuit of the cut-off relay, so that a separate scanning needle can be dispensed with.

Preferably, the thread guide is mounted to move in its longitudinal direction on the thread guide holder, against the action of a return spring.

The present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows the arrangements of a known needle monitor; Figure 2 shows one embodiment of a safety device according to the present invention in side view and partly in section; and Figure 3 is a front view of the device shown in figure 2 in partial cross-section.

According to figure 1, in a known arrangement a needle monitor 1 with its scanning needle 2 is mounted on a carriage 3 of a knitting machine so that the scanning needle 2 travels directly over a needle bed 6 of the machine and the knitting 7 being produced thereon. When using a normal thread guide 4 (drawn in dot-dash lines), the use of the scanning needle 2 causes no problems, however when one uses an insertion thread guide 5 (drawn in full line), which for reasons relating to knitting technology is located directly above the knitting 7, then it is in the scanning region of the scanning needle 2 and therefore makes use of the latter impossible. In this case, it was hitherto necessary to dispense with the scanning needle 2 so that there was no safety mechanism to stop the machine when a bulge in the knitting occurred.

According to the embodiment of the invention illustrated in figures 2 and 3, a block-like carriage 12 with a thread guide holder 14 is mounted to move on a thread guide rail 8, in which holder 14 the thread guide 18 is mounted to move in its longitudinal direction over a limited distance. For this purpose, the thread guide 18 comprises a slot 11, in which a pin 10 attached to the thread guide holder 14 engages, so that the length of the slot 11 determines the possible movement. A return spring 15 located between the contact surfaces of the thread guide holder 14 and of the thread guide 18, which spring acts as a compression spring, normally keeps the thread guide 18 in its lower vertical operative position illustrated in figures 2 and 3.

A wire 20 which is electrically earthed, is attached to the thread guide holder 14 by means of a screw 19, the end of which wire adjacent the thread guide 18, passes into a piece of wire 16 which is not electrically insulated and is bent at right-angles to the longitudinal direction of the thread guide 18. The other end of the wire 20 is connected electrically to a sliding contact 13, which is installed in the carriage 12 and is in contact with a contact rail 9 which is likewise electrically earthed and mounted on the thread guide rail 8. Attached to the thread guide 18 is a contact pin 17, which in the operative position of the thread guide 18, extends in the horizontal direction, at a slight distance below the piece of wire 16 and at right-angles to the latter.This contact pin 17 and the piece of wire 16 form the contacts of a switch located in the excitation circuit of a cut-off relay (not shown) which operates as a cut-off contact. This cut-off relay is electrically connected to the contact rail 9 and, by way of earth, i.e. by way of the electrically conducting metal parts of the apparatus, to the contact pin 17.

When the thread guide 18 moving directly above the needle bed 6 and the knitting 7, which guide is preferably an insertion thread guide, strikes against the knitting which is bulging, then it is subjected to a vertical force component, which moves the latter upwards against the action of the spring 15, in the direction of the arrow in figure 2, so that the contact pin 17 comes into contact with the piece of wire 16, due to which the cut-off relay stops the knitting machine.

In another embodiment which is not shown, the thread guide 18 may also be mounted pivotally on the thread guide holder 14, so that when it strikes against an obstacle, it is deflected rearwards or laterally, preferably once more against the action of a return spring and thus actuates a cut-off contact for the purpose of stopping the knitting machine. It is also possible that when it strikes an obstacle, the thread guide is moved out of an engaged position, so that in this case a return spring can be dispensed with.

The cut-off contact may have any suitable construction. The safety device described according to the invention can be used in principle on flat knitting machines of any type.

Claims

CLAIMS:

1. A safety device for a flat knitting machine for monitoring the knitting produced on the machine and the needles of the machine, comprising a movable sensor, which can be moved out of a normal operating position by striking against an obstacle to actuate a cut-off contact and thereby stop operation of the knitting machine, the sensor itself comprising thread guide for the knitting machine and is mounted to move on a thread guide holder.

2. A safety device according to Claim 1, in which the thread guide is able to move against the action of a return spring, which attempts to keep the latter in the normal operating position.

3. A safety device according to Claim 1 or 2, in which the thread guide is mounted to move in its longitudinal direction on the thread guide holder.

4. A safety device according to Claim 3, in which a slot is provided in either the thread guide or the thread guide holder and a pin engaging in this slot is provided in either the thread guide holder or the thread guide respectively.

5. A safety device according to Claim 1 or 2, in which the thread guide is pivotally mounted on the thread guide holder.

6. A safety device according to any one of the preceding Claims, in which the cut-off contact comprises a contact pin attached to the thread guide and a piece of wire attached in an electrically insulated mannerto the thread guide holder, which piece of wire can come into electrical contact with the contact pin when the thread guide is moved and which piece of wire is connected in an electrically conducting manner to a sliding contact that is installed in a carriage of the machine supporting the thread guide holder and that is able to move along a thread guide rail, the piece of wire being in electrical contact also with a contact rail that is attached in an insulated manner to the thread guide rail and connected to a cut-off relay.

7. A safety device for a flat knitting machine substantially as hereinbefore described with referpence to Figures 2 and 3 of the accompanying drawings.