GB2198459A - Improvements in and relating to carpet looms - Google Patents

Abstract

A carpet weaving loom of the Axminster Gripper type having at least one sensing means comprising a sensor 24 and emitter 26 and which traverses the loom in synchronisation with a knife holder 14 and which determines sequentially, for each yarn carrier, the presence or absence of a yarn 8 held by the associated gripper 4. Counting means are provided which determines the position of the sensing means during each transverse stroke of the knife holder. The counting means controls the sensing means so that the presence or absence of yarn held by a gripper is only determined for a given number of yarn carriers. The sensing means and counting means transmit signals to a data collection unit designed to indicate the location of any missing yarn ends. <IMAGE>

Description

IMPROVEMENTS IN AND RELATING TO CARPET LOOMS This invention relates to carpet weaving looms and more particularly to Axminster gripper looms.

Axminster Gripper looms have a plurality of vertically disposed yarn carriers arranged parallel to each other across the loom. Each yarn carrier is equipped with a number of yarn stations which carry yarns supplied from behind the carrier. Each carrier has a rotatable gripper associated with it. At its first position each gripper grips a yarn held at a station of the associated carrier. Relative movement between the carrier and the gripper forms the length of yarn required and a knife blade supported in a knife holder traverses the loom servering the yarns adjacent to the carriers. A series of knives may be provided depending on the width of the loom. The grippers then rotate to their second position where the portion of yarn held by each gripper is inserted into the carpet backing to form a complete row of tufts.

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

Production of a complete length of carpet on a loom of the type described is dependent on the availability of a continuous supply of yarn at each station of the carriers. The absence of yarn at a station may be due for example to a knot in the yarn, preventing it from passing through the station or the yarn supply to the station may unexpectedly run out. This will result in a missing tuft in the carpet which can only be repaired manually. Equally, even with a continuous supply of yarn at each station, a faulty gripper which fails to grasp the yarn end from the station of its associated carrier will have the same effect.Without some means of detection of missing yarns between each carrier and its associated gripper, each length of carpet produced will have to be checked for any missing tufts and repaired by hand if gaps are found, a labour extensive, lengthy and correspondingly expensive process.

A method of detecting missing yarn ends which has been proposed is to provide an emitter and receiver of radiant energy arranged to traverse the loom in conjunction with the knife holder. The detection of energy by the receiver indicates the presence of a yarn between a gripper and a station of its associated carrier . This method while successful at registering the absence of yarn ends fails to provide information as to the location of the corresponding missing tuft within the length of carpet produced.

One proposal which overcomes this difficulty has been to provide a second emitter and receiver which also traverse the loom in synchronization with the knife blade and which determine the presence or absence of the grippers. This arrangement allows the location of any missing tufts to be accurately determined facilitating mending. However, this arrangement has the disadvantage that it is not suitable for broad looms where more than one knife blade is required. The number of blades across a loom depends on the loom width and the length of stroke the knife holder makes. When a plurality of knife blades is required each blade will be associated with one section of the loom and each section will contain the same number of carriers.

A stroke of the knife holder on a broad loom causes each knife blade to cut the yarns within its associated section but also results in an overlap wherein each knife blade traverses part of the adjacent section.

This overlap is necessary to ensure that every yarn within a section is cut. The arrangement described above if used on broad looms would cause the yarn stations at the beginning of each section to be checked twice for the presence or otherwise of a gripper and the presence or otherwise of a yarn.

According to the present invention a carpet weaving loom of the type described has at least one sensing means which traverses the loom in synchronization with a knife holder and which determines sequentially for each yarn station, the presence or absence of a yarn held by a gripper and counting means which determines the position of the sensing means during each traverse stroke of the knife holder and which controls the sensing means so that the presence or absence of a yarn held by a gripper is only determined for a given number of yarn stations, the sensing means and counting means transmitting signals to a data collection unit designed to indicate the location of any missing yarn ends.

The advantage of this arrangement is that it may be used equally successfully on narrow width or broad width looms to locate exactly the position of any missing tufts within the carpet thereby speeding up the repair process and saving both time and expense.

Preferably a sensing means is provided for each section which traverses its section in synchronization with the associated knife blade and with the sensing means and knife blades in the other sections.

Conveniently a single counting means is connected to the knife holder of a section at one end of the loom and determines the position of the sensing means associated with that section and therefore the position of the sensing means in all the other sections by counting the number of the carrier which the sensing means is checking for the presence of a yarn held by the corresponding gripper, the counting means sending a signal to the data collection unit indicating the location of the sensing means so that when all the carriers in the section have been checked, the data collection unit renders all the sensing means inoperative until the loom begins its next traverse stroke.

The preferred arrangement therefore has the additional advantage that only a single counting means is necessary no matter how many knife blades there are across the loom and the counting means may be easily attached to an existing loom.

A currently preferred counting means has a fixed member and a sliding member which is connected to the knife holder of the end section of the loom so that it moves in synchronization with the knife blade and sensing means of that section, relative movement between the fixed member and sliding member enabling the number of the carrier which the sensing means is checking to be determined and transmitted to the data collection unit.

The data collection unit may be arranged to indicate the sections and position within the sections of any missing tufts for each row of pile.

Preferably control means are provided to stop the loom if a given number of yarns are absent in a single traverse stroke of the loom. Preferably the control means may also stop the loom if, at a particular location, yarn is absent for a given number of rows of pile.

The invention will now be described by way of example only with reference to the accompanying figures in which:- Figure 1 is a side view of part of a loom according to the invention; Figure 2 is a view in the direction of arrow I of figure 1; and Figure 3 is a view in the direction of arrow II of figure 1 with the grippers and carriers omitted.

Referring to Figure 1, the loom is of conventional construction having a plurality of vertically disposed yarn carriers aligned parallel to each other across the loom, one of which is shown at 2. Each carrier has associated with it a gripper, 4, the grippers being mounted in front of the carriers and also aligned across the loom. The number of carriers per inch across the loom width is called the pitch, for example in a twelve foot wide loom with a pitch of 7 there are one thousand and eight carriers and associated grippers.

Each carrier has a number of yarn stations 6 disposed vertically one above the other, usually eight although twelve and sixteen are known. The yarn stations 6 are each supplied with yarns 8 from bobbins or the like mounted behind the carriers, the yarns being held in position by small leaf springs 10 within the body of the carrier.

Usually each station carries a different colour or shade of yarn and selection of a colour required to form the carpet pattern is made by means of a jacquard linked to each of the carriers by a thin wire. The carriers are raised so that the required colours are in a common position. In Figure 1 the second yarn from the top 8' has been selected.

The gripper grasps the yarn end in the selected station and the carrier is then moved away from the gripper to the position shown in Figure 1, forming the required length of tufts of pile 12 to be woven into the carpet.

The cutting assembly, generally shown at 14 is then caused to move down onto the yarn stretching between the carriers and the grippers so as to cut the tufts 12.

Subsequently, the carriers are lowered to their set position ready for re-selection for the next pile row.

The cutting assembly comprises firstly a knife slide rail 16 to which is fixedly mounted a knife comb 18. The comb has hound toothed serrations cut into one edge with the number of serrations per inch equal to the pitch of the loom. Each serration aligns with one of the yarns stretched between the carriers and grippers. The cutting assembly secondly comprises knife blades 20 aligned parallel to each other and slideably mounted on the knife slide rail by knife holders 22. These blades traverse the face of the comb and co-operate with it to sever the yarns located in the serrations. This operation is shown in side view in Figure 3.

The number of knife blades is dependent on the loom width and the length of stroke the slide arrangement makes which is a matter of preference. For example four and sixteen blades can be used on a twelve foot wide loom. If sixteen blades were used then for a pitch of seven each would cut sixty three yarns. If we consider the loom as divided into sections defined by the stroke of a knife blade, then each section in the example above would comprise 63 carriers and associated grippers. For a narrow loom only one knife blade will be required and the loom may be considered as a single section.

In order to detect the presence or absence of a yarn between the station of a carrier and its associated gripper after the yarns have been stretched by the gripper and prior to severing, sensing means are provided, one for each section. The sensing means comprises firstly a receiver 24 mounted on the knife holder 22 in front of the knife blade 20 considered in the direction of movement of the knife blade when cutting the yarns, and secondly an emitter 26 held in a slide 28 so arranged that the emitter and receiver and therefore the knife blade traverse a section together.

The emitter which comprises a light bulb, is positioned to direct a light beam across each of the tensioned yarn lengths held by a gripper as shown in Figure 1. When no yarn is present between the yarn station and the gripper, the receiver which comprises a light sensitive cell will detect the light beam. The position of the emitter and receiver can be seen in greater detail in Figure 3.

In a further embodiment the emitter and receiver may both be mounted on the support member; the emitter positioned to direct energy at the yarn so that, in the presence of a yarn, it would be reflected onto the receiver.

Figure 2 shows a section where yarn is missing between the sixth carrier and gripper pair counted from right to left. The counting means, generally designated by 30(see figure 3 where a part of one section of the loom specifically the section on the end of the loom is also shown) comprises a pitched comb 32, mounted in a slide 34, and a receiver 36 and emitter 38 attached to the slide on either side of the pitched comb. The comb is forced to move in synchronisation with the knife blade 20, by a connection rod 40 between the comb and the knife holder 22 of the knife blade 20. The comb has as many slots as the number of carriers within a section.

The sequence of detection of missing yarn ends is as follows: As the cutting means traverses the loom the receivers 24 which are attached to each knife holder look at each intended yarn location sequentially from right to left across their associated section as described above.

Simultaneously receiver 36 detects and counts the slots in the pitched comb to determine at which of the yarn stations, ends are missing. For example in a twelve foot wide loom with a pitch of 7 and sixteen blades there are sixteen sections each comprising 63 carriers. If we designate the sections A to P from right to left section A is that shown in figure 3 where the yarns have been numbered from 1 to 63 from right to left. In section A receiver 24 detects the presence or otherwise of a yarn stretched between number 1 gripper and carrier, receiver 24 in all the other sections detect the presence or absence of number 1 and at the same time. Simultaneously receiver 36 detects and counts the number 1 slot in the comb, which is numbered from left to right, and transmits a signal to a data collection unit indicating that the sensing means is checking number 1 carrier for a yarn end.

This continues until all 63 yarn stations have been checked for a yarn held by the associated gripper.

When the receiver 36 indicates to the data collection unit that the 63rd gripper and carrier pair has been reached and the presence or otherwise of a yarn end detected, the data collection unit cuts the power to the sensing means in all sections. Therefore, even if the knife blade overshoots the end of its associated section, as it well may in looms of the type described, the yarn stations at the beginning of each section will not be checked twice for the presence or otherwise of a yarn end held by a gripper.

If during a traverse stroke of the loom one or more of the receivers 24 detects a gap(missing yarn end)then an electronic signal is transmitted to the data collection unit causing one or more light bulbs to light up each of which corresponds to a particular section thus indicating to the operater that ends are missing in those sections. At the same time a signal is pulsed from the data collection unit to a print out unit which records in which sections ends were missing. The data collection.

unit also pulses information received from receiver 36 to the print out unit as to the number of the carrier which is being checked thereby enabling the exact position of each missing end to be recorded.

Each row of pile is scanned as the loom moves through the weaving cycle until the length of carpet required is completed. For each length produced the print out unit provides records of missing ends, the exact position of any ends missed and the total number missing.

This provides an invaluable aid in mending the carpet after weaving.

It will be appreciated that both the receivers 24 and receiver 36 and the data collection unit must be capable of receiving and analysing information at very high speed. One advantage of having a single counting means is that only one signal is necessary to indicate the location of all the sensing means on the loom at any time.

Conveniently control means are provided connected to the data collection unit. The control means may be arranged to stop the loom if the number of missing yarn ends in a single row of pile reaches a preset total.

Similarly the control means may also stop the machine if the total number of missing ends at any time during the production of a length of carpet equals another preset number. The control means may be further arranged to allow an end to be missed consecutively at the same location for only a certain number of rows of pile before stopping the loom. All these tolerances may be adjusted up or down.

The operator of the loom according to the present invention may therefore arrange the control perameters to compromise between the desirability of minimum down time and required quality of the finished length of carpet.

Whether or not the control means are used during the production of a length of carpet, the operator will be provided with a print out recording the exact position of each missing end on completion of weaving which will greatly facilitate mending. One of the main problems with a Gripper Axminster loom is when one end of a particular colour is required repeatedly and a fault will then result in a line of missing tufts down the length of the carpet.

By setting the control means to only allow yarn to be missed at the same location for a small number of rows of pile the operator can prevent this occurring. This is a great advantage if the quality of carpet required is such that a few random missing tufts will not be significant and the operator does not intend to repair the carpet on completion of weaving.

Claims (16)

1. A carpet weaving loom of the type described having at least one sensing means which traverses the loan in synchronisation with a knife holder and determines sequentially for each yarn carrier, the presence or absence of a yarn held by the associated gripper and counting means which determine the position of the sensing means during each transverse stroke of the knife holder and which controls the sensing means so that the presence or absence of a yarn held by a gripper is only determined for a given number of yarn carriers, the sensing means and counting means transmitting signals to a data collection unit designed to indicate the location of any missing yarn wends.

2. A carpet weaving loom as claimed in Claim 1 wherein the counting means determines the position of the sensing means by counting the number of carriers which the sensing means has checked.

3 A carpet weaving loom as claimed in either Claim 1 or 2 wherein the sensing means sends a signal to the data collection unit indicating the position of the sensing means, the data collection unit rendering the sensing means inoperative when the given number of yarn carriers have been checked for the presence or absence of a yarn held by the associated grippers.

4. A carpet weaving loom as claimed in any preceding claim having a plurality of knife blades each of which is supported in a knife holder and each of which cuts the yarns in a respective section of the loom.

5. A carpet weaving loom as claimed in Claim 4 wherein each knife holder has an associated sensing means.

6. A carper weaving loom as claimed in Claim 5 wherein the counting means determines the position of only one of the sensing means.

7. A carpet weaving loom as claimed in either Claim 5 or 6 wherein the data collection unit renders all the sensing means inoperative when the given number of yarn carriers have been checked for the presence or absence of a yarn held by the associated grippers.

8. A carpet weaving loom as claimed in any preceding claim wherein the counting means comprises a fixed member and a sliding member connected to a knife holder so that it moves in synchronisation with the sensing means associated with that holder, relative movement between the fixed member and sliding member enabling the position of the sensing means to be determined.

9. A carpet weaving loom as claimed in any preceding claim wherein the data collection unit is arranged to indicate the position of any missing tufts for each row of pile.

10. A carpet weaving loom as claimed in any preceding claim wherein control means are provided to stop the loom if a given number of yarns ar absent in a single transverse stroke of the loom.

11. A carpet weaving loom as claimed in any preceding claim wherein control means are provided to stop the loom if, at a particular yarn carrier, the absence of yarn is detected for a given number of rows of pile.

12. A carpet weaving loom as claimed in any preceding claim wherein the sensing means comprise an emitter of radiant energy and a receiver for the energy, energy from the emitter traversing the intended location of the length of yarn between the carrier and gripper and passing to the receiver thereby allowing the presence or absence of a yarn end to be determined.

13. A carpet weaving loom as claimed in Claim 12 wherein the emitter of radiant energy is mounted on the associated knife holder and the receiver for that energy is mounted in a slide so arranged that the emitter and receiver traverse the loom in synchronisation with each other.

14. A carpet weaving loom as claimed in Claim 12 wherein the emitter and receiver are both mounted on the knife holder, the emitter positioned to direct energy at the intended location of the yarn so that, in the presence of a yarn, it will be reflected on to the receiver.

15. A carpet weaving loom as claimed in'any of Claims 8 to 14 wherein the sliding member of the counting means comprises a pitched comb mounted in the fixed member, the receiver and emitter of radiant energy being attached to the fixed member on either side of the pitched comb and the spacing between the slots of the pitched comb being equal to the spacing between the yarn carriers of the loom.

16. A carpet weaving loom substantially as herein described with reference to the accompanying figures.