GB2096651A

GB2096651A - Gripper Axminster looms

Info

Publication number: GB2096651A
Application number: GB8205286A
Authority: GB
Original assignee: HUDSON IRVIN Ltd; MACKAY HUGH PLC
Current assignee: HUDSON IRVIN Ltd; MACKAY HUGH PLC
Priority date: 1981-03-10
Filing date: 1982-02-23
Publication date: 1982-10-20
Also published as: GB2096651B

Abstract

A gripper Axminster carpet loom includes sensing means (18), preferably a photoelectric device, which traverses the loom ahead of the knife blade (12) and determines sequentially whether or not yarns (4) and grippers (6) are present at each split (2). The sensing means (18) transmits signals to associated electronic control means as to the presence or otherwise of the yarns (4) and grippers (6). Means are provided to keep the sensors fluff-free. <IMAGE>

Description

SPECIFICATION Improvements in and relating to carpet weaving looms This invention relates to looms for weaving carpets, more particularly gripper Axminster carpets.

Gripper Axminster carpets are produced on looms having a plurality of laterally aligned splits or groups of warp threads, the looms including, for each split, a carrier provided with a series of stations or compartments each of which is supplied with pile-yarn from an associated bobbin mounted in a bank or creel frame located behind the carrier. Each carrier has associated therewith a gripper rotatable through a predetermined arc between a first position in which it can take hold of a yarn in a station or compartment of the associated carrier, relative movement between the gripper and the carrier away from one another resulting in the required length of yarn for each tuft being drawn off, a knife blade traversing the loom to sever said tufts adjacent the carriers, and a second position in which the gripper places the tuft of yarn in the carpet backing.The carriers can also be moved relative to the grippers, under the control of a Jacquard, whereby the station or compartment of a carrier with the desired yarn therein is presented to the gripper at each cycle thereof.

Such a loom is of conventional construction and will hereinafter be referred to as 'a loom of the type described'.

The production of a complete carpet on such a loom is dependent, amongst other things, on the continuous supply of pile-yarn to each of the associated stations or compartments of the carriers. The absence of yarn at a station will result in missing tufts in the carpet and will necessitate manual repair of the carpet after its completion.

Clearly this can be a laborious, time-consuming and therefore expensive procedure.

The absence of yarn at a station may result from the associated bobbin or cheese unexpectedly running out of yarn or from the presence of a knot in the yarn, such as that joining the yarn of two cheeses together, which cannot pass through the station of the carrier to enable a tuft to be formed.

Heretofore it has been proposed to attempt to determine the absence of yarn by providing a plurality of mechanical fingers, one for each split, which can be moved up and down as a unit during each cycle of the loom into and out of contact with the yarns as they are formed into tufts. If a yarn is not present, the associated finger, instead of contacting the non-electrically conducting yarn, contacts a metal part of the loom such as the associated gripper and completes an electrical circuit which indicates the absence of the yarn and stops the loom for each missing yarn.

However, such an arrangement has proved to have a number of disadvantages not the least of which is that the presence of the fingers obstructs access to the knife blade, guide rail and associated equipment, while the finger mechanism is not readily programmable, other than by providing control equipment associated with each finger, to given an immediate indication of the presence or otherwise of the yarns.

According to the present invention there is provided a loom of the type described in which, when the required lengths of yarn have been drawn off by relative movement between the grippers and the carriers and said lengths of yarn are under tension, the knife blade traverses the loom to sever sequentially said lengths of yarn and form the tufts, the loom comprising sensing means which, while the yarns are under tension, traverse the loom ahead of the knife blade, considered in the direction of movement of the blade during the severing process, and determines sequentially the presence or otherwise of said yarns, said sensing means transmitting signals to associated electronic control means which are programmed to indicate the absence of yarn between any carrier and its associated gripper.

Conveniently the knife blade is mounted on a support member which also carries the sensing means whereby said knife blade and sensing means traverse the loom together.

A currently preferred sensing means comprises a photoelectric device emitting infra-red radiation which is directed onto the yarns sequentially during a traverse of the loom, said radiation, in the presence of a yarn, being reflected from said yarn back to a receiving portion of the device whereby the presence or otherwise of the yarns can be sequentially determined.

Conveniently the photoelectric device emits further infra-red radiation which is directed onto the grippers sequentially during a traverse of the loom and which, in the presence of a gripper, is reflected from said gripper back to a second receiving portion of the device whereby the persence or otherwise of the grippers can be sequentially determined.

Preferably the photoelectric device transmits continuous beams of infra-red radiation one directed onto the yarns and one directed onto the grippers, although the device may be synchronised to transmit concurrently first and second pulses of infra-red radiation for each split during a traverse of the loom, said pulses being directed one onto the yarn and one onto the gripper of a split and, in the presence of said yarn and gripper; each pulse being reflected back to the associated receiving portion of the device prior to emission of the next following pulse.

With such arrangements, the presence of a gripper as determined by the further infra-red radiation provides a stable reference signal for the control means, indicating to said control means that a yarn should be present at that particular split - if, for a given split, reflected radiation is received back at both receiving portions of the photoelectric device, the information that gripper and yarn are both present is stored in the control means; if, on the other hand, the presence of a gripper is indicated, but no reflected signal is detected from the associated yarn, this information is stored in the control means as a missing tuft.

If a gripper is missed out of the loom, the absence of said gripper as determined by the photoelectric device will indicate to the control means that no yarn should be present and that that particular location should be ignored in subsequent computation of the information gathered by the control means.

The control means may be arranged to give a visual read-out after each cycle of the loom of any absent yarns, together with detail of the relevant carriers.

The control means may be arranged to stop the loom after a predetermined number of absent yarns have been detected.

By way of example only an embodiment of the invention will now be described in greater detail with reference to the accompanying drawings of which: Fig. 1 shows part of a loom according to the invention with a tuft about to be severed, and Fig. 2 is a view in the direction of arrow 'A' of Fig. 1.

Referring to the drawings, the basic loom is of relatively standard construction comprising a plurality of horizontally aligned carriers one of which is indicated at 2, there being one carrier per split and typically six carriers per inch across the width of the carpet. Each carrier has for example eight small compartments or stations therein disposed vertically one above the other with each compartment being supplied with yarn from an associated bobbin in a creel frame (not shown) behind the carriers. For convenience only one yarn 4 is shown in the drawings.

In front of the carriers are mounted a plurality of grippers one of which is shown at 6, one gripper being associated with each carrier 2.

Each gripper 6 is pivotal about a-horizontal axis through a predetermined arc of about 1 800 between the upper position shown in Fig. 1 in which a beak member 8 of the gripper can take hold of an associated preselected yarn in the carrier, and a lower position (not shown) in which a tuft of yarn is placed in the carpet backing.

During each cycle of the loom, the beak members 8 of the grippers 6 take hold of the yarn projecting from the associated carrier and draw off the required amount of yarn for each tuft. A Van Dyke comb 10 then drops down over the tensioned yarns with the yarns extending through associated gaps in the comb. A knife blade 12 carried on a knife box 14 slidable along a guide rail 1 6 then traverses the loom, said blade 12 cooperating with the comb to sever through the tensioned yarns and to form the tufts. The grippers 6 then swing down and lay the tufts between the fine chains of the carpet backing or foundation.

Detection of any missing yarns between the carriers 2 and the grippers 6 once the yarns have been tensioned and prior to severing is achieved as follows.

Sensing means in the form of a scanner indicated generally at 1 8 is mounted on the knife box 14 in front of the knife blade 12 considered in the direction of movement of the knife blade during severing of the yarns to form the tufts.

The scanner 1 8 comprises a housing 20 in which are mounted a pair of photoelectric cells 22, 24 one behind the other considered from in front of the loom, each cell including a transmitter 26 and a receiver 28.

The transmitter 26 of the rearmost cell 22 is positioned to direct a continuous, sharply defined beam of infra-red radiation onto the tensioned lengths of yarn adjacent the grippers 6, radiation reflected from the yarns being directed onto the receiver 28 of said cell 22.

The transmitter 26 of the front cell 24 is positioned to direct a further continuous, sharply defined beam of infra-red radiation onto the beaks 8 of the grippers 6, radiation reflected from the beaks 8 being directed onto the associated receiver 28 of the cell 24.

For a 36 inch wide carpet having 6 splits per inch and in which the knife box traverses the loom in 0.5 seconds, it will be appreciated that the receivers 28 of the cells 22 and 24 must be capable of receiving and analysing information once every 1/600 seconds -- i.e. once for every split during a cycle of the loom.

The arrangement is such that, as the scanner 1 8 passes each split, the presence of a gripper is determined by reception back at the receiver 28 of the cell 24 of radiation reflected from the gripper.

This indicates to control electronics associated with the scanner that a yarn should be present at that particular split. Thus, if the presence of a yarn is detected by the receiver 28 of the cell 22 at the same time es the associated gripper signal is received at the cell 24, the memory of the control equipment stores the information; if no yarn signal is detected, the memory stores the information as a missing tuft.

If a gripper is deliberately left out of the loom at a particular split and no reflected radiation is therefore returned to the receiver 28 of the cell 24 at that split, the control equipment is programmed to realise that no yarn should be present at that split and that the split can be ignored in subsequent computation of the gathered information.

If a gripper is inadvertently out of position at any given split, due possibly to deformation of the gripper beak to one side or other of its correct position or due to breakage of the gripper or jamming of the gripper, the control electronics are arranged to determine at the end of a scan that the full complement of gripper signals has not been received by the scanner, which information is indicated by the control equipment.

The information gathered by the scanner during each traverse of the loom - i.e. whether or not any yarn is absent and, if so, the location of the missing yarn with reference to the number of the split in question -- is available for visual display on a display unit (not shown) connected to the scanner.

Conveniently the scanner and associated electronic equipment for translating and transmitting the information gained by the scanner are interconnected with the loom control mechanism to switch off the loom, with the grippers down, once a predetermined number of absent yarns have been detected.

Clearly the number of tufts that must be missing from a carpet before the loom is stopped can be chosen to suit requirements and in particular to combine economy of production (including minimum down-time of the ioom) with quality of the end product. It is to be noted that the above-detailed known arrangement for locating absent yarns stopped the loom for every missing tuft.

The radiation emitted by the cells 22, 24 is chosen to be capable of reflection by all the colours of yarn in a given carpet, sufficient radiation being reflected from the darker colours to ensure a detectable signal at the receiver 28 of the cell 22.

Conveniently means are provided on the loom to ensure that the cells 22, 24 are kept clean and free of fluff. Such means may comprise, for example, a source of compressed air directing a constant blast or intermittent blasts of air onto said cells, or may comprise a wiping mechanism.

Thus there is provided sensing means on a loom which determines sequentially the presence or otherwise of yarn prior to the formation of a tuft and which enables said information to be displayed to an operator. It will be appreciated that the described arrangement can detect an absent yarn even if there is yarn visible at the carrier but where the yarn is not under tension between the carrier and the gripper as can happen, as mentioned above, when a knot in the yarn prevents it being pulled out the carrier.

Further the presence of a scanner does not obstruct access to the knife blade, guide rail and associated equipment as occurred in the abovementioned known arrangement.

Claims

1. A carpet weaving loom of the type described in which, when the required lengths of yarn have been drawn off by relative movement between the grippers and the carriers and said yarns are under tension, the knife blade traverses the loom to sever sequentially said lengths of yarn and form the tufts, the loom comprising sensing means which, while the yarns are under tension, traverse the loom ahead of the knife blade, considered in the direction of movement of the blade during the severing process, and determines sequentially the presence or otherwise of said yarns, said sensing means transmitting signals to associated electronic control means which are programmed to indicate the absence of yarn between any carrier and its associated gripper.

2. A loom as claimed in claim 1 in which the knife blade is mounted on a support member which also carries the sensing means whereby said knife blade and sensing means traverse the loom together.

3. A loom as claimed in claim 1 or claim 2 in which the sensing means comprises a photoelectric device emitting infra-red radiation which is directed onto the yarns sequentially during a traverse of the loom, said radiation, in the presence of a yarn, being reflected from said yarn back to a receiving portion of the device whereby the presence or otherwise of the yarns can be sequentially determined.

4. A loom as claimed in claim 3 in which the photoelectric device emits further infra-red radiation which is directed onto the grippers sequentially during a traverse of the loom and which, in the presence of a gripper, is reflected from said gripper back to a second receiving portion of the device whereby the presence or otherwise of the grippers can be sequentially determined.

5. A loom as claimed in claim 4 in which the photoelectric device transmits continuous beams of infra-red radiation one directed onto the yarns and one directed onto the grippers.

6. A loom as claimed in claim 4 in which the photoelectric device is synchronised to transmit concurrently first and second pulses of infra-red radiation for each split during a traverse of the loom, said pulses being directed one onto the yarn and one onto the gripper of a split and, in the presence of said yarn and gripper, each pulse being reflected back to the associated receiving portion of the device prior to emission of the next following pulse.

7. A loom as claimed in any one of claims 1 to 6 in which the control means are arranged to give a visual read-out after each cycle of the loom of any absent yarns, together with detail of the relevant carriers.

8. A loom as claimed in any one of claims 1 to 7 in which the control means are arranged stop the loom after a predetermined number of absent yarns have been detected.

9. A loom as claimed in any one of claims 1 to 8 and including means for ensuring that the sensing means are kept clean and free of fluff.

10. A carpet weaving loom substantially as described with reference to and as illustrated by the accompanying drawing.

10. A loom as claimed in claim 9 in which the cleaning means comprise a source of compressed air directing a constant blast or intermittent blasts of air onto the sensing means.

11. A carpet weaving loom substantially as described with reference to and as illustrated by the accompanying drawings.

Print claims as originally filed and new claims 1 to 10 filed on 18 May 1982.

1. A carpet weaving loom of the type described in which, when the required lengths of yarn have been drawn off by relative movement between the grippers and the carriers and said yarns are under tension, the knife blade traverses the loom to sever sequentially said lengths of yarn and form the tufts, the loom comprising sensing means which, while the yarns are under tension, traverse the loom ahead of the knife blade, considered in the direction of movement of the blade during the severing process, and determines sequentially, for each split, the presence or otherwise of a gripper and the presence or otherwise of a yarn, said sensing means transmitting signals, one associated with each gripper and one associated with each yarn, to associated electronic control means which are programmed to indicate, for each split, the absence of a gripper and/or the absence of yarn between the carrier and its associated gripper.

3. A loom as claimed in claim 1 or claim 2 in which the sensing means comprises a photoelectric device having a first source of infrared radiation which is directed onto the grippers sequentially during a traverse of the loom, said radiation, in the presence of a gripper, being reflected from said gripper back to a first receiving portion of the device whereby the presence or otherwise of the grippers can be sequentially determined, the photoelectric device having a further source of infra-red radiation which is directed onto the yarns sequentially during a traverse of the loom and which, in the presence of a yarn, is reflected from said yarn back to a further receiving portion of the device whereby the presence or otherwise of the yarns can be sequentially determined.

4. A loom as claimed in claim 3 in which the photoelectric device transmits continuous beams of infra-red radiation one directed onto the grippers and one directed onto the yarns.

5. A loom as claimed in claim 3 in which the photoelectric device is synchronised to transmit concurrently first and second pulses of infra-red radiation for each split during a traverse of the loom, said pulses being directed one onto the gripper and one onto the yarn of a split and, in the presence of said gripper and yarn, each pulse being reflected back to the associated receiving portion of the device prior to emission of the next following pulse.

6. A loom as claimed in any one of claims 1 to 5 in which the control means are arranged to give a visual read-out after each cycle of the loom of any absent grippers and/or yarns, together with detail of the relevant carriers.

7. A loom as claimed in any one of the claims 1 to 6 in which the control means are arranged to stop the loom after a predetermined number of absent yarns have been detected.

8. A loom as claimed in any one of claims 1 to 7 and including means for ensuring that the sensing means are kept clean and free of fluff.

9. A loom as claimed in claim 8 in which the cleaning means comprise a source of compressed air directing a constant blast or intermittent blasts of air onto the sensing means.