GB2085039A

GB2085039A - Shuttleless looms

Info

Publication number: GB2085039A
Application number: GB8129793A
Authority: GB
Original assignee: Kombinat Textima VEB
Current assignee: Kombinat Textima VEB
Priority date: 1980-10-03
Filing date: 1981-10-02
Publication date: 1982-04-21
Also published as: CH655139A5; CS244526B1; CS682381A1; DE3127542A1; FR2491508A1; BE890586A; DD153398A1; NL8103725A

Abstract

A rapier or tape loom has a weft insertion assembly including a gripper member 5; 6 which is connected to a drive 1; 2 constituted by a linear motor (polysolenoid) which is controllable via a respective electronic control system 25; 26. The drive may also drive the pile wires of a pile fabric loom. <IMAGE>

Description

SPECIFICATION A gripper loom This invention relates to a gripper loom having at least one weft insertion assembly which is disposed outside the shed and has a gripper member connected to a drive for reciprocating said gripper member horizontally transversely of the web of fabric.

The term "gripper member" used herein is intended to denote an elongate member, such as a rod or tube, of rigid or flexible construction.

Mechanical drives for gripper members are known in which the gripper members are driven rectilinearly by means of a crank drive, levers and linkages (Federal German Patent Specification 1 059 849). Mechanical gripper member drives are also known in which a cam couple gear transmission drives a gearwheel forwards and backwards (Federal German Auslegeschrift 1 535 491). The gearwheel engages in a rack connected to the gripper member body, constructed as a hollow body.

An electro-mechanical drive for a gripper member is also known (Federal German Offenlegungsschrift 2 707 687), in which a disc rotor motor is used for each of the oppositely moved gripper members. Each disc rotor motor directly drives a pinion which meshes with teeth of the gripper members.

The disc rotor motors are controlled by a common process computer in accordance with a stored programme. The process computer has a feedback via associated control circuits to the disc rotor motor and the loom drive.

All these methods share the feature that the required rectilinear motion of the gripper member in the shed can be produced only indirectly by means of variously expensive mechanisms, i.e. the driving force does not act directly on the gripper member.

As a result, in these drives considerable masses must be accelerated and decelerated. For this reason such systems are liable to additional costs and increased wear. Consequently, the reliability of such gripper member drives is substantially reduced.

Federal German Offenlegungsschrift 2 420 433 discloses a gripper shuttle loom in which the shuttle, which runs through the shed to insert the weft, is actuated by asynchronous linear motors disposed on both sides of the shed. The shuttle is guided inside the shed by guide plates disposed on the slay.

Such gripper shuttle drive has the disadvantage that when the shuttle has been "picket", its movement can no longer be influenced inside the shed. Another disadvantage is the jerky acceleration and braking of the shuttle which cause the risk of frequent yarn breakages.

Furthermore, the weft reservoir in the shuttle means that relatively considerable masses must be accelerated and decelerated, and this overheats the weft insertion assembly; the loss of mass of the shuttle due to the constantly reduced weft yarn store causes different shuttle velocities, which are not the optimum ones for treating the weft most gently. If the linear motor is to operate directly to accelerate and brake the shuttle, the shuttle must completely enter the air gap of the linear motor. This produces unfavourable constructional conditions for both the linear motor and the shuttle.

It is an object of the invention to simplify the gripper member drive and enhance its reliability.

The invention aims at providing means for driving the gripper members directly in accordance with a controlled sequence of motion.

Accordingly, the present invention consists in a gripper loom having at least one weft insertion assembly which is disposed outside the shed and has a gripper member (as herein defined) connected to a drive for reciprocating said gripper member horizontally transversely of the web of fabric, characterised in that a linear motor is provided for driving the or each gripper member and that the respective linear motor is controllable via an electronic control system. In an advantageous embodiment of the invention the linear motor is a polysolenoid-like linear motor with a stator having an opening of circular, oval, square or oblong shape, at least one gripper member having a cross-section adapted to the shape of the stator opening being drivable therein.

Conveniently, two or more gripper members extend through the stator of the linear motor and are drivable thereby.

Preferably, in the or each linear motor at least one rod or one such runner of aluminium or copper is drivable, and the free end of such runner has a connection to at least one gripper member.

Advantageously, disposed on both sides of the gripper loom is a polysolenoid-like linear motor which is drivably connected to the gripper member extending respectively therethrough as far as the centre of the shed, each linear motor being controlled by an electronic control system.

In one embodiment of the invention disposed on only one side of the gripper loom is a polysolenoid-like linear motor, by means of which the gripper member extending therethrough is movable through the whole shed.

Preferably, the gripper member is constituted by a rigid tube of aluminium or copper or by a flexible spiral hose of aluminium, copper or a copper braiding.

Conveniently, the flexible gripper member which emerges from the linear motor at its end remote from the shed is guided arcuately.

Advantageously, associated with at least one gripper member of the or each linear motor is a path-measuring device which is connected to the inputs of the electronic control system for transmission of pulses of the gripper member motion.

Since the gripper members are driven directly by the linear motor, there is no need for additional mechanical elements which are subject to rapid wear in other constructions. A substantially simplified gripper member shape can be used instead of the prior art expensive special shapes.

The gripper member drive of the invention uses substantially less material, has a smaller mass and takes up less space, requires less energy and is cheaper to manufacture. Another advantageous feature is the very simple mounting and exchangeability of the drive system and parts thereof. In contrast with mechanical methods using gear transmissions, the gripper members can be positioned relatively accurately on both sides by means of the path-measuring device and control system. As a result the invention can be used for all known weft insertion methods based on the gripper principle, in which the yarn is inserted by constraint.

The electronic control system enables the speed of the gripper members to be controlled steplessly.

In contrast with many mechanical drives, the nature of the drive of the invention permits a gripper motion which tends towards zero outside the shed, this being advantageous as regards the space occupied.

The monitoring of the correct motion of the gripper member in time, combined with warning of malfunction, which results in the immediate stoppage of the gripper loom, prevents destruction to the gripper members, the slay and the textile material.

Also advantageously the acceleration and braking of the gripper members is effected via a field of force, resulting in a substantially reduced degree of wear in comparison with known mechanical drives.

For the purpose of weft searching, advantageously the gripper members are not introduced into the web. In prior mechanical drives this requires a relatively expensive synchronous clutch. In contrast, in the case of a drive using tubular linear motors, it is enough simply to interrupt the starting pulse in known manner, so that the weft-introducing members are not moved into the shed.

In an advantageous embodiment of the invention, each electronic control system comprises a starting unit for the linear motors, a synchronisation logic for the linear motors and a main drive of a braking unit for the linear motors, a common reversing logic of the linear motors, a common creep speed operation unit of the linear motors, and a power unit for each linear motor: the input of the starting unit is connected to the pulse transmitting system of the main drive shaft, its output being connected to the power unit of the linear motor; the first input of the synchronisation logic is connected to the pathmeasuring system, its second input being connected to the pulse transmitting system, a first output to the braking unit, and a second output to the main drive of the loom; a first input of the braking unit is connected to the synchronisation logic, a second input to the creep speed operation unit, its first output to the power unit, and its second output to the reversing logic; the first output of the creep speed operation unit extends to the associated braking unit, its second output extending to the power unit; the reversing logic is connected via an input to the associated braking unit and via an output to the associated power unit; and the power unit has a first input for the starting unit, a second input for the braking unit, a third input for the creep speed operation unit, a fourth input for the reversing logic, and an output for the linear motor.

According to an optional feature of the invention, the starting unit comprises a starting logic and an interruptor for the starting logic.

According to a further optional feature of the invention, the synchronisation logic comprises a fixed value memory, a comparator and an evaluation logic which are connected via the outputs, the synchronisation logic also having a pulse counter; and an input of the evaluation logic is connected to the pulse transmitting system, an output of the evaluation logic is connected to the main drive, an input of the pulse counter to the path-measuring system and its output to the comparator.

In one embodiment of the invention the braking unit has an operating logic and a braking logic, the operating logic comprising a working memory, a fixed value memory, a comparator and an evaluation logic; the output of the working memory and the output of the fixed value memory are connected to the comparator, the output of the comparator being connected to the evaluation logic; the output of the working memory is connected to the pulse counter of the synchronisation logic, the output of the evaluation logic being connected to the working memory of the brake logic; and the brake logic also comprises the comparator and the brake control system; a further input of the working memory is connected to the creep speed operation logic, the output of the working memory to the comparator, an input of the comparator to the pulse counter, an output of the comparator to the reversing logic and the braking control device; and the output of the braking control device extends to the power unit of the linear motor.

In one embodiment of the invention the creep speed operation unit comprises a creep speed unit logic, a fixed value memory, an input unit and a frequency transformer; and an output of the creep speed operation logic is connected to the fixed value memory, its outputs to the associated working memory, a further input of the creep speed operation logic to the input unit, the output of the input unit to the frequency transformer, and its output to the power unit of the linear motor.

Preferably, the reversing logic is connected via its inputs to the associated braking unit and via its outputs to the associated power unit of the respective linear motor.

Conveniently, the gripper members are brakable in the centre of the shed or outside the shed by direct current, the movement of each gripper member being limited by a respective abutment.

Advantageously, the magnetic return of the or each linear motor is constructed as a fixed iron rod which is disposed outside the shed and which extends into the linear motor and on which the gripper member slides.

The iron rod forming the magnetic return may be mounted at one end on the loom frame and at the other end in the linear motor.

One advantageous feature of the invention in the case of a flexible gripper member drive is that the magnetic return of the or each linear motor is constructed as a fixed iron rod which is straight where it extends into the linear motor but is curved outside the linear motor and on which a gripper member of flexible aluminium or copper spiral hose or flexible copper wire braiding slides outside the shed, while inside the shed the flexible gripper is guided by rectilinearly disposed guide plates.

The gripper member may be made up of telescopic individual elements, the individual elements sliding on the magnetic return and also the return itself being at least twice as long as the linear motor, and the remaining individual element being at least as long as the linear motor.

Finally, according to another optional feature of the invention the cooling air of each linear motor can be branched to clean the gripper heads.

In order that the invention may be more readily understood, reference is made to the accompanying drawings which illustrates diagrammatically and by way of example embodiments thereof, and in which: Fig. 1 shows the gripper member drive with the electronic control system, Fig. 2 is a block circuit diagram of the electronic control system of the weft insertion system, Fig. 3 shows a further embodiment of the gripper member drive, Fig. 4 shows a linear motor with double runner, Fig. 5 shows a flexible gripper member drive with a tubular linear motor, and Fig. 6 shows a gripper drive with telescopic gripper members.

To make the drawing clearer, the known parts of conventional gripper member drives are not shown in the gripper member drive illustrated in Fig. 1. Attached to the loom frame on both sides of the gripper loom outside the shed is a known asynchronous cylindrical linear motor (polysolenoid), in the embodiment illustrated a tubular linear motor 1; 2. The tubular linear motor 1; 2 has in known manner a cylindrical stator 3; 4.

In the gripper drive illustrated in Fig. 1 the opening of the stator 3; 4 has a circular shape. However, it can alternatively have an oval, square or oblong shape. In the simplest case the runner of each tubular linear motor 1; 2 is a copper or aluminium tube (Fig. 1) which also acts as a rigid gripper member 5; 6 and slides over a magnetic return 7; 8 which has a large mass and is therefore stationary. Bearing blocks 9; 10 fix the magnetic return 7; 8, consisting of an iron rod, on the loom frame side. The magnetic return 7; 8 is retained inside the linear motor 1; 2 by bearings 11'; 12'.

At their shed-side ends, the gripper members 5; 6 each carry a gripper head 13; 14, each member carrying a rebound disc 1 5; 1 6 at their ends remote from the shed. The length of the gripper members 5; 6 with the gripper heads 13; 14 is such that on the one hand, when the weft is inserted, yarn transfer can take place in the shed via the gripper heads 13; 14, the rebound discs 1 5; 1 6 not yet abutting the stator 3; 4 of the respective tubular linear motor 1 and 2, and on the other hand, during the change of shed the gripper heads 13; 14 have completely left the shed.

The gripper heads 13; 1 4 are so constructed geometrically that when the rebound discs 1 5; 1 6 abut the stator 3; 4 respectively of the particular tubular linear motor 1 and 2, they are not destroyed. Disposed above each linear motor 1 and 2 respectively is an air cooling means 17; 18 which on the one hand cools the corresponding tubular linear motor 1; 2, and on the other hand cleans the particular gripper head 13; 14 via an air branching 1 9 and 20 respectively.

To recognise the position of the gripper members 5; 6, use is made of path-measuring devices 21; 22, which are installed on guide pins 11; 1 2 at the shed-side end of the magnetic returns 7; 8. The path-measuring devices 21; 22 comprise in known manner optical-electronic devices which, when the gripper member 5; 6 move, produce pulses which can be fed via inputs 23; 24 to an electronic control system 25 and 26 respectively. In a known manner which is therefore not illustrated, the slay and the shedopening members are moved by a main drive 27, a cage rotor motor.The main driving shaft 28 carries a code disc 29 which is scanned in known manner by a pulse-transmitting system 30, for example an inductive initiator or a photoelectric cell, and therefore reports the slay position or the opening condition of the shed via a lead 31 to inputs 32; 33 and 34; 35 respectively of electronic control system 25; 26. Each electronic control system 25; 26 has an output 36; 37 to the main drive 27 of the gripper loom and also an output 38; 39 to the tubular linear motor 1 and 2 respectively. As a result, the electronic control system 25 is associated with the weft insertion system illustrated on the left-hand side of Fig. 1, the electronic control system 26 being associated with the right-hand weft insertion system. The construction of the electronic control system 25 corresponds to that of the electronic control system 26.

For certain functions, the electronic systems 25 and 26 use common units. Since the construction of the electronic control system 25 corresponds to that of the electronic control system 26, hereinafter only the electronic control system 25 will be described. Each electronic control system 25 and 26 respectively comprises a starting unit 40, a synchronisation logic 41, a braking unit 42, a common reversing logic 43, a common creep speed operation unit 44, and a power unit 45. The starting unit 40 has an input 32 (33), which is connected to the pulse transmitting system 30 of the main driving shaft 28. The starting unit 40 has an output 46 which extends to the input 46' of the power unit 45 of the tubular linear motor 1 (2).

The starting unit 40 (Fig. 2) consists of a starting logic 47 and an interruptor 48 for the starting logic 47. The synchronisation logic 41 (Fig. 2) has an input 34 (35) which is connected to the pulse transmitting system 30 of the main driving shaft 28. The synchronisation logic 41 has a further input 23 (24) which extends to the pathmeasuring device 21 (22). A first output 36 of the synchronisation logic 41 is connected to the main drive 27, a second output 49 being connected to the braking unit 42. The synchronisation logic 41 comprises a fixed value memory 50, a comparator 51, an evaluation logic 52 and a pulse counter 53.

The fixed value memory 50 is connected via output 54 to the comparator 51, the comparator 51 being connected via output 55 to the evaluation logic 52. The output 36 (37) makes the connection between the evaluation logic 52 and the main drive 27. The input 34 connects the pulse transmitting system 30 to the evaluation logic 52. The path-measuring device 21 (22) is connected to the pulse counter 53 via the input 23 (24). Output 56 of the pulse counter 53 branches to the output 49, which extends to the braking unit 42. The other branch of the output 56 extends to the input 57 of the comparator 51. The braking unit 42 comprises an operating logic and a braking logic. The operating logic has a working memory 58, a fixed value memory 59, a comparator 60 and an evaluation logic 61. The braking logic consists of a working memory 62, a comparator 63 and a braking control device 64.

Input 65 of the working memory 58 is connected to the synchronisation logic 41, output 66 of the working memory 58 being connected to the comparator 60. Similarly, output 67 of the fixed value memory 59 is connected to the comparator 60.

Output 68 of the comparator 60 extends to evaluation logic 61. Output 69 of the evaluation logic 61 is connected to the working memory 62, a further output 70 being connected to comparator 63, and an input 71 of the working memory 62 being connected to a creep speed operation logic 72. Input 73 of the comparator 63 extends to the pulse counter 53, an output 74 extending to the reversing logic 43 and the braking control device 64. Output 76 of the braking control device 64 is connected to input 76' of the power unit 45 of the linear motor 1 (2).

A common creep speed operation unit 44 is associated with the two electronic control systems 25; 26.

The creep speed operation unit 44 comprises the creep speed operation logic 72, fixed value memory 77, input unit 78 and frequency transformer 79. Input 80 of the creep speed operation logic 72 is connected to the fixed value memory 77, a further input 81 being connected to the input unit 78. Output 82 of the creep speed operation logic 72 extends to the working memory 62. Output 84 of the input unit 78 is connected to the frequency transformer 79, its output 85 being connected to the input 85' of the associated power unit 45 of the corresponding linear motor 1.

A common reversing logic 43 is also associated with the electronic control systems 25; 26. Via inputs 86 the reversing logic 43 is connected to the associated braking unit 42 and via output 87 to input 87' of the power unit 45 of the linear motor 1.

In a further embodiment (Fig. 3) a rod 88 is drivable in the tubular linear motor 2. The tubular rod 88 slides on the magnetic return 8. The rod 88 has a joint 88a which makes a connection with one or more gripper members 6. For this construction a different type of linear motor, for example a flat design is suitable, which moves an appropriately constructed runner of aluminium or copper.

A further embodiment is illustrated in Fig. 4. A double runner variant of a tubular linear motor 89 drives two aluminium or copper tube gripper members 90; 91 by the field of magnetic force of a double runner stator 92. A magnetic return 93; 94 is fixed in its longitudinal axis by retaining rods 95; 96 firmly clamped on abutments 103; 104 and joints 97; 98. The gripper members 90; 91 are also guided outside the shed in bearings 99; 100 and are connected via a rigid but adjustable connection 101 outside the shed. The connection 101 also acts as an abutment which abuts an abutment 102 of the double runner stator 92 or adjustable abutments 103; 1 04.

In another embodiment (Fig. 5) the tubular linear motor 2 directly drives a gripper member 105 constructed as a flexible tube, for example, a copper wire braiding, or a copper or aluminium spiral hose. An iron return 106 extends straight into the tubular linear motor 2, but outside the tubular linear motor 2 is constructed as a bent iron rod 107 which is connected to the loom frame or the foundation 108. An abutment 109 is disposed at the end of the iron rod 1 07. The flexible gripper member 105 slides on the return 106 outside the shed. Inside the shed the gripper member 105 is guided straight by means of known guide plates 110 which are attached to the slay 111.Also disposed on the gripper head 112 is an abutment 113 which limits the travel of the gripper member 105 outside the shed by a second abutment 114.

In the embodiment of the gripper member drive illustrated in Fig. 6, a telescopic gripper member 11 5 is driven inside the tubular linear motor 1. The gripper member 1 5 consists of a number of tubular individual elements 1 117 of aluminium or copper which are telescopically connected. The individual element 1 17 guided on the magnetic return 11 8 is twice as long as the tubular linear motor 1. The magnetic return 11 8, consisting of an iron rod, is of equal length. The remaining individual elements are at least as long as the tubular linear motor 1. The individual element 117 has an abutment 119. When the individual elements 1 16; 117 are moved into the shed, the abutment 119 abuts the tubular linear motor 1. When the individual elements 1 16; 117 move out of the shed, the abutment 11 9 abuts guide 120. While half the length of the individual element 117 remains in the tubular linear motor 1, the full length of the remaining individual elements 11 6 remains in the tubular linear motor 1. The return 118 is guided in front of the tubular linear motor 1 by a pin 120'. The individual element 11 7 is slotted appropriately. Instead of the tubular linear motors 1; 2 disposed on the loom frame on both sides outside the shed, only one tubular linear motor 1 or 2 or 89 may be used.

In that case the gripper member 5 or 6 or 90; 91 extending through the tubular linear motor 1; 2; 89 or the flexible gripper member can be long enough to be moved through the whole shed. The drive of the gripper members 5; 6; 90; 91 or the flexible gripper member 105 of a gripper loom was described hereinbefore. Of course, the drive may also be conceivably used on other textile machines to produce the same sequence of motion. For example, the embodiment illustrated in Fig. 3 is mainly suitable for moving the pile-wire of a pile-wire loom into and out of the shed by linear motors via a joint 88a.

The operation of the gripper member drive will now be described with reference to Figs. 1 and 2: In a manner which is known, and therefore not illustrated, the slay and the shed-opening members are moved by the main drive 27. At the main driving shaft 28 the pulse transmitting system 30 continuously interrogates the position of the code disc 29 and therefore the crank angle of the main drive 27 and the slay position and the opening condition of the shed. At a predetermined crank angle, at which the slay is in its rear position and the shed is opened, and the gripper members 5; 6 are in their outer abutment position, i.e.

outside the shed, the starting unit 40 associated with each tubular linear motor 1; 2 receives a pulse from the pulse transmitting system 30 via the input 32; 33. The amplified pulse is supplied via the power unit 45 to the tubular linear motor 1 and 2 respectively. By their moving field the latter immediately act on the gripper members 5; 6 and move them into the opened shed. This movement can be interrupted by the interruptor 48 of the starting unit.

The movement of the gripper members 5; 6 into the shed generates pulses in the pathmeasuring devices 21; 22. The pulses are counted in the pulse counter 53 of the synchronisation logic 41 and fed via the output 49 to the working memory 58 of the braking unit 42. As a result, the maximum number of pulses-reached during the weft-inserting movement of the gripper members 5; 6 is written into the working memory 58. As a result the working memory 58 receives the particular number of braking pulses which was necessary for the stroke of the gripper members 5; 6 just taking place, having regard to the different frictional values and therefore the differing after-travel paths of the gripper members 5; 6. The fixed value memory 59 contains the optimum number of pulses for weft insertion.Both values are interrogated by the comparator 60 and fed to the evaluation logic 61. If there are differences from the optimum number of pulses, the evaluation logic 61 writes a corrected number of braking pulses into the working memory 62, making optimum braking possible. In this way the weft-insertion system is adapted to many external parameters, such as changed sliding properties due to wear or temperature changes, fluctuations in mains voltage and therefore altered drive speeds, different drawing-off forces of the weft yarn, and the influence of different weft yarn materials on the insertion system. This adaptation enables the gripper heads 13; 1 4 to be positioned precisely in the centre of the shed. The pulses of the pulse counter 53 are also fed via the input 73 to the comparator 63.When the comparator 63 finds that the number of pulses of the pulse counter 53, fed via the input 73, agrees with the number of braking pulses fed via output 70 of the working memory 62, the comparator 63 operates the brake control device 64. The same procedure is of course also followed in the electronic control system 26. As a result, the tubular linear motors 1 and 2 are braked on the principle of direct current braking via the power units 45, and therefore the gripper members 5 and 6 are stopped, each in accordance with the distance they have travelled and their over-run travel.When both gripper members 5; 6 have been positioned and the yarn has been transferred by the gripper heads 13; 1 4, a pulse from the comparator 63, which is fed via input 86 to the reversing logic 43 causes the latter to reverse the tubular linear motors 1; 2 via output 87 and power units 45. As a result, the gripper members 5; 6 are moved out of the shed.

Consequently the path-measuring devices 21; 22 again deliver pulses which are processed in the same manner as in the case of the weft insertion disclosed hereinbefore. When the gripper members 5; 6 reach their end position outside the shed, the braking units 42 start to operate again.

The tubular linear motors are stopped by direct current braking. After the gripper members 5; 6 have emerged from the zone of the slay, the latter can move and-beat up the weft yarn just introduced against the fell. After the beating-up, the new shed is opened and the pulse transmitting system 30 announces to each starting logic 40, as disclosed hereinbefore, the readiness for the insertion of a fresh weft yarn. As a result the weftinserting cycle described above starts all over again.

To check the synchronisation between the crank rotation of the main drive 27 and the drive of the gripper members 5; 6, predetermined parts of the travel covered by the gripper members 5; 6 are monitored by means of the path-measuring devices 21; 22. This is done by feeding the pulses of the pulse counter 53 to the comparator 51. The comparator 51 makes sure that the actual number of pulses agrees with the required number of pulses stored in the fixed value memory 50. At predetermined times, the evaluation logic 52 interrogates the comparator 51. At predetermined crank angles of the main drive 27, the interrogation times are determined by the pulse transmitting system 30 by pulses which are fed via inputs 34; 35 of the evaluation logic 52 to the associated synchronisation logic 41.If malfunctioning makes synchronous running uncertain, the evaluation logic 52 feeds via its output 36 or 37 to the main drive 27 a stop pulse, which stops the main drive 27 and uncouples the gripper loom from the main driving motor. When the synchronisation unit 41 has obtained a given number of pulses from the path-measuring device 21 or 22, the unit 41 actuates the braking unit 42 via output 49, so that the tubular linear motors 1; 2 are stopped by direct current braking. If both the gripper members 5; 6 are in the shed and transfer has taken place, the reversing logic operates as disclosed hereinbefore.

If the gripper loom is to operate in the creep speed mode, this is done via the input unit 78.

Creep speed operation is produced by frequency transformation by means of the frequency transformer 79 which is connected to the power units 45. Since in creep speed operation the number of braking pulses required to initiate braking differs from normal operation, the fixed value memory 77 comes into operation. The braking operation is then controlled via the creep speed operation logic 72, via its outputs 82; 83.

The subsequent braking operation and the reversal of the tubular linear motors 1; 2 was already disclosed. No particular features need be disclosed as regards the operation of the embodiments of the linear motor and associated runners disclosed in Figs. 3 to 6. If only one linear motor is used, use is made of only one of the electronic control systems 25 or 26 disclosed.

Claims

1. A gripper loom having at least one weft insertion assembly which is disposed outside the shed and has a gripper member (as herein defined) connected to a drive for reciprocating said gripper member horizontally transversely of the web of fabric, characterised in that a linear motor is provided for driving the or each gripper member and that the respective linear motor is controllable via an electronic control system.

2. A gripper loom as claimed in claim 1, wherein the linear motor is a polysolenoid-like linear motor with a stator having an opening of circular, oval, square or oblong shape, at least one gripper member having a cross-section adapted to the shape of the stator opening being drivable therein.

3. A gripper loom as claimed in claim 2, wherein two or more gripper members extend through the stator of the linear motor and are drivable thereby.

4. A gripper loom as claimed in any of claims 1 to 3, wherein in the or each linear motor at least one rod or one such runner of aluminium or copper is drivable, and the free end of such runner has a connection to at least one gripper member.

5. A gripper loom as claimed in any of claims 1 to 3, wherein disposed on both sides of said loom is a polysolenoid-like linear motor which is drivably connected to the gripper member extending respectively therethrough as far as the centre of the shed, each linear motor being controllable by an electronic control system.

6. A gripper loom as claimed in any of claims 1 to 3, wherein disposed on only one side of said loom is a polysolenoid-like linear motor by means of which the gripper member extending therethrough is movabie through the whole shed.

7. A gripper loom as claimed in any of claims 1 to 6, wherein the gripper member is constituted by a rigid tube of aluminium or copper or by a flexible spiral hose of aluminium, copper or a copper braiding.

8. A gripper loom as claimed in claim 7, wherein the flexible gripper member which emerges from the linear motor at its end remote from the shed is guided arcuately.

9. A gripper loom as claimed in any of claims 1 to 5, wherein associated with at least one gripper member of the or each linear motor is a pathmeasuring device which is connected to the inputs of the electronic control system for transmission of pulses of the gripper member motion.

10. A gripper loom as claimed in any of claims 1, 5, 6, 7 and 9, wherein each electronic control system comprises a starting unit for the linear motors, a synchronisation logic for the linear motors and a main drive of a braking unit for the linear motors, a common reversing logic of the linear motors, a common creep speed operation unit of the linear motors, and a power unit for each linear motor, an input of the starting unit is connected to a pulse transmitting device of the main drive shaft, its output being connected to the power unit of the linear motor, a first input of the synchronisation logic is connected to a pathmeasuring device, a second input is connected to the pulse transmitting device, a first output is connected to the braking unit, and a second output to the main drive of the loom, a first input of the brake unit is connected to the synchronisation logic, a second input to the creep speed operation unit, its first output to the power unit and its second output to the reversing logic, a first output of the creep speed operation unit extends to the associated braking unit, its second output extends to the power unit, the reversing logic is connected via an input to the associated braking unit and via an output to the associated power unit, and the power unit has a first input for the starting unit, a second input for the braking unit, a third input for the creep speed operation unit, a fourth input for the reversing logic and an output for the linear motor.

11. A gripper loom as claimed in claim 10, wherein the starting unit comprises a starting logic and an interruptor for the starting logic.

12. A gripper loom as claimed in claim 10 or 11, wherein the synchronisation logic comprises a fixed value memory, a comparator and an evaluation logic which are interconnected via outputs of the fixed value memory and of the comparator, the synchronisation logic also having a pulse counter, and an input of the evaluation logic is connected to the pulse transmitting system, an output of the evaluation logic is connected to the main drive, an input of the pulse counter to the path-measuring device and its output to the comparator.

13. A gripper loom as claimed in any of claims 10 to 12, wherein the braking unit has an operating logic and a braking logic, the operating logic comprising a working memory, a fixed value memory, a comparator and an evaluation logic, an output of the working memory and an output of the fixed value memory are connected to the comparator, an output of the comparator being connected to the evaluation logic, an output of the working memory is connected to the pulse counter of the synchronisation logic, an output of the evaluation logic being connected to the working memory of the braking logic, and the braking logic also comprises the comparator and the braking control device, a further input of the working memory is connected to the creep speed operation logic, an output of the working memory to the comparator, an input of the comparator to the pulse counter, an output of the comparator to the reversing logic and the braking control system, and the output of the braking control device extends to the power unit of the linear motor.

14. A gripper loom as claimed in any of claims 10 to 13, wherein the creep speed operation unit comprises a creep speed unit logic, a fixed value memory, an input unit and a frequency transformer, and an output of the creep speed operation logic is connected to the fixed value memory, its outputs to the associated working memory, a further input of the creep speed operation logic to the input unit, the output of the input unit to the frequency transformer, and its output to the power unit of the linear motor.

1 5. A gripper loom as claimed in any of claims 10 to 14, wherein the reversing logic is connected via its inputs to the associated braking unit and via its outputs to the associated power unit of the respective linear motor.

1 6. A gripper loom as claimed in any of claims 1 to 15, wherein the gripper members are brakable in the centre of the shed or outside the shed by direct current, the movement of each gripper member being limited by a respective abutment.

17. A gripper loom as claimed in any of claims 1 to 16, wherein the or each linear motor has a magnetic return which is constructed as a fixed iron rod which is arranged outside the shed and which extends into the linear motor and on which the gripper member slides.

18. A gripper loom as claimed in claim 17, wherein said iron rod is mounted at one end on the loom frame and at the other end in the linear motor.

19. A gripper loom as claimed in claim 17 or 18, wherein the magnetic return of each linear motor is constructed as a fixed iron rod which is straight where it extends into the linear motor but is curved outside the linear motor and on which a flexible gripper member of aluminium or copper spiral hose or flexible copper wire braiding slides outside the shed, while inside the shed the flexible gripper member is guided by rectilinearly disposed guide plates.

20. A gripper loom as claimed in any of claims 1 to 7, wherein the gripper member is made up of telescopic individual elements, the individual elements sliding on the magnetic return and also the magnetic return itself are at least twice as long as the linear motor and the remaining individual elements are at least as long as the linear motor.

21. A gripper loom as claimed in any of claims 1 to 20, wherein the or each linear motor has a means for supplying cooling air to the motor, said means being branchable for supplying part of the cooling air to gripper heads for the purpose of cleaning.

22. A gripper loom, substantially as herein described with reference to and as shown in the accompanying drawings.