GB2059455A - Improvements in or relating to looms with stationary weft supply - Google Patents

Abstract

A weft inserter 50 and receiver 10 which meet in the shed and transfer the weft from one to the other have their gripper operated electromagnetically. As the inserter 50 starts its insertion movement spring loaded pivoted jaws 56, 58, which are held open by a stationary cam acting on a follower 80, close to grip the weft and the jaw 56 is held in its closed position, against the action of its spring by a catch 70. The receiver 10 has a fixed jaw 18 and a pivoted spring loaded jaw 22 that is held in its open position, against the action of its spring, by a catch 34. At the transfer position a first electromagnet is operated to release the catch 34 of the receiver 10 so that its pivoted jaw is moved by its spring to grip the weft, still held by the inserter, against the fixed jaw 18. A second electromagnet is then operated to release the catch 70 of the inserter 50 so that the jaw 56 is moved by its spring to the open position to release the weft for withdrawal from the shed by the receiver 10. <IMAGE>

Description

SPECIFICATION Improvements in or relating to looms with stationary weft supply The invention is concerned with looms having a stationary weft supply and more particularly to gripper type looms of the kind in which there are two grippers carried by respective rapiers, one of which known as the giver gripper carries a weft yarn from one end of the loom to a changeover position near to the centre of the reedspace, and the other known as the taker gripper, accepts the weft yarn from the giver at the changeover position, and carries it to the other end of the loom. The rapiers on which the grippers are mounted may be either rigid rapiers which are reciprocated along a rectilinear path, or flexible band type rapiers, which are wrapped around driving wheels at the end of the loom, and unwrap from those wheels as they are projected towards the centre of the reedspace.The present invention has in fact been developed in association with rigid rapiers, driven by a rack-and-pinion driving mechanism, but it is to be understood that the invention could be used with grippers fitted to any kind of rapier so long as the grippers carry out the weft transfer function at the changeover position.

The primary object of the invention is to provide a method and means of actuating the grippers for weft changeover, which does not have any deleterious effect on the warp threads, and it is a further object of the invention to provide grippers which operate in a reliable manner, so as to avoid the incidence of weft failure.

According to one aspect of the invention the jaws of a gripper in a giver and taker type gripper loom are caused to open or close as part of the weft changeover operation by energisation of an electro-magnet disposed outside the warp shed activating a catch on the gripper. At the changeover position, it is usually necessary to activate the gripper jaws of one or both grippers.

Thus, if the taker has selt-activating spring-loaded jaws which are merely forced apart by the weft sufficiently to allow the weft to be caught by the taker, then the jaws of the giver must be activated to release the weft. Alternatively, it may be necessary to activate the giver jaws to release the weft and the taker jaws to grip the weft. The problem of gripper jaw activation at weft changeover is that the grippers are near to the centre of the reedspace at the time of the changeover and hence in the warp shed. Some gripper looms are provided with a stationary cam on the sley which activates the gripper jaws each time the gripper moves over the cam, but in that case, some of the lower warp yarns are nipped between the cam and the part of the gripper which is moved by the cam and this has a deleterious effect on the warp.It has also been proposed to move a jaw operating member from a position outside the warp shed through the top sheet of warp threads (passing between two of the warp threads) to engage with a part of the gripper for activating the jaws. Again, this mechanism is likely to damage some of the warp threads. The principal advantage of the present invention is that there is no nipping or rubbing of the warp threads, because no mechanical action takes place through either of the warp sheets.

Preferably both the giver and the taker grippers have jaws activated electro-magnetically, and it is further preferred that they are activated successively, the taker gripper gripping the weft thread before the giver gripper releases it, so that for a short period during changeover the weft thread is held in both grippers. This ensures that the weft thread is always under control during changeover. It is further preferred that the taker gripper arrives at the inward limit of its movement before the giver gripper arrives at the inward limit of its movement, so that the taker gripper is stationary relatively to the loom sley at the instant when the giver gripper presents the weft to the jaws of the taker gripper.

It is further preferred that the electro-magnet(s) is or are energised in synchronism with the loom cycle.

According to a second aspect of the invention a gripper for use in a gripper type loom has an articulated jaw biased into one of its open and closed positions, and catch means for retaining the articulated jaw in the other of its open and closed positions against the biasing force, the catch means being adapted to be released by magnetic means located outside the gripper to allow the articulated jaw to move under the biasing into the open or closed position. Thus, if the articulated jaw is biased into the closed position, then the catch means holds it in the open position until released by the magnet, when the jaw will be allowed to move into the closed position.

According to a preferred feature of this second aspect of the invention a giver gripper has a pair of weft gripping jaws both of which are articulated on the gripper body, the first being biased into the closed position and the second being biased into the open position, there being catch means adapted to hold the second jaw in the closed position, the catch means being arranged to be released by co-operating magnetic means on the loom so that the second jaw is allowed to open when the catch is released by the magnetic means.

Preferably the first jaw has a cam follower adapted when engaged by a cam on the loom, to cause the first jaw to move into the open position.

It is also preferred that the first jaw has a lost motion connection with the second jaw whereby the later part of movement of the first jaw in the opening direction causes the second jaw to be moved into its closed position and engages the catch means with the second jaw. The catch means is preferably self-latching, and may take the form of a spring-loaded catch which allows a neb of the second jaw to pass it in the closing direction of movement of the second jaw, but then engages with the neb and prevents return movement of the second jaw towards the open position.

Either or both of the jaws of the giver gripper may be biased by gravity or by spring loading.

There may be stop means on the gripper engageable by the first jaw to prevent the latter moving with the second jaw when the second jaw moves to its open position, but the stop means should be located so that it permits a small increment of movement of the first jaw with the second jaw to ensure that the stop does not prevent firm closure of the jaws in the closed position.

A giver gripper constructed in accordance with the preferred form of the second aspect of the invention outlined above is adapted to operate as follows:- Assuming that its jaws are in the closed position gripping a weft yarn; at the changeover position (when the weft has already been presented to the taker gripper) the catch is released by the electro-magnetic appertaining to the giver gripper and the second jaw moves to its open position; the first jaw is effectively prevented from following the first jaw by its engagement with the stop, so that the jaws open and release the weft; when the follower engages with the cam towards the outer end of the gripper movement, the first jaw is moved into an open position and during the latter part of this motion it moves the second jaw into the closed position (where it is retained by the catch); and when the gripper follower moves off the cam on the next inward movement of the gripper, the first jaw is allowed to move into the closed position to grip another weft yarn in the then closed jaws.

According to another preferred feature of the second aspect of the invention a taker gripper has a stationary jaw and a pivoted jaw the latter being resiliently loaded into the closed position but having a follower adapted to engage with a stationary cam on the loom to move the jaw to the open position, there being a catch adapted to retain the pivoted jaw in the open position and being further adapted to be released by magnetic means on the loom sley. The catch may be selflatching as described above with reference to the giver gripper.

A taker gripper constructed in accordance with the preferred form of the second aspect of the invention outlined above is adapted to operate as follows: Assuming that its pivoted jaw is in the open position and held in that position by the catch, the taker gripper moves to the changeover position, where the giver gripper places the weft yarn between its jaws; the electro-magnet associated with the taker gripper is then energised, releasing the catch, and allowing the pivoted jaw to move into the closed position, so that it grips the weft yarn; the taker gripper then moves outwardly of the loom, and when it arrives outside the warp shed, a cam engages with the follower and moves the pivoted jaw into the open position, releasing the weft yarn, and causing the catch to engage with the pivoted jaw; when the taker gripper next moves inwardly, although its follower becomes disengaged from the cam, the jaw is held in the open position by the catch.

A giver and taker type gripper loom in accordance with the invention, will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a side view of taker gripper; and Figure 2 is a side view of a giver gripper.

The loom is generally of known construction, involving rigid rapiers one at each side of the loom, driven by a rack-and-pinion motion, so that at each pick of the loom, the two rapiers move inwardly towards each other and then outwardly away from each other. At the giver gripper end of the loom, there is a stationary weft supply, including a weft selector and presentation mechanism, whereby a selected weft yarn can be placed in the path of the inwardly moving gripper, so that that weft yarn is carried into the warp shed by the giver gripper. The taker gripper is adapted to receive the weft thread from the giver gripper at the changeover position near to the centre of the reedspace, and to carry the weft thread out at the taker end of the loom. These general features of the loom have only been briefly described, because they do not form part of the present invention.

Referring to Figure 1, there is shown a taker gripper 10, having a body 12 mounted at the inner end a rigid rapier 14. The taker gripper has a bottom jaw 16 formed integral with the body 12, and therefore rigid with the body. As illustrated, the bottom jaw 1 6 has a pointed snout 18, and a jaw pad 20, located in a recess immediately to the rear of the snout 1 8.

An articulated top jaw 22 is pivoted on the gripper body 12 at 24, and at its frond end, is equipped with a pad 26, engageable in the closed position with the pad 20 of the stationary lower jaw 16. The top jaw 22 has a tail 28 at the rear extremity of which there is laterally projecting neb 30, and the top jaw 22 is biased by spring loading such as a torsion spring, into the closed position.

As an alternative to the spring loading, the weight distribution of the top jaw about its pivotal axis may be such that it is loaded by gravity into the closed position, but it is preferred to provide spring means for this purpose, in order to ensure that there is a firm ciamping action on the weft thread, when the top jaw is in the closed position.

A catch 32 is pivoted on the body 12 at 34, and is generally of beil-cranked formation, one arm 36 thereof extending in a generally horizontal direction, and being made of a metal such that it can be attracted by a magnet. The catch 32 is spring loaded into a latching position illustrated in Figure 1, where its upper end engages with the neb 30 of the top jaw 22 (the latter being in the open position) so that the catch holds the top jaw in the open position.

It will be appreciated, that if the catch 34 is caused to turn in a clockwise direction as illustrated, its upper end will disengage from the neb 30, and this will allow the top jaw to move under its own resilient loading into the closed position. Whenever the top jaw is turned against its own resilient loading towards the open position, the underside of the neb engages with a sloping face 38 at the top of the catch 34, turning the latter slightly in a clockwise direction, to allow the neb 30 to pass, but as soon as the neb 30 is below the top of the catch 34, the latter returns in an anticlockwise direction into the jaw holding position illustrated. In other words, the catch 34 can be regarded as a self-activating latching system for the top jaw, which is adapted to hold the top jaw in the open position against its spring loading.

There is let into the sley of the loom a small electromagnet, at a position which is immediately beneath the arm 36 of the catch 32, when the taker gripper arrives at the changeover position.

The driving mechanism for the rapier 14 is arranged to halt the gripper 12 in the position where the arm 36 is immediately over the electromagnet each time the gripper 12 arrives at the changeover position during the loom cycle. There is also an electrical control circuit synchronised with the loom driving mechanism, and adapted to produce energisation of the electro-magnet which is thus associated with the taker gripper, once in each loom cycle, at a time when the weft yarn has been placed across the then open jaws 1 6 and 22 of the taker, immediately before the taker rapier 14 begins its outward motion. The electrical circuit need not be described in detail, but it should be mentioned that the signal for energisation of the electro-magnet is obtained by discharge of a capacitor at the appropriate time in the loom cycle.

Turning now to Figure 2 of the drawings, there is illustrated a giver gripper 50, having a body 52 secured to the inner end of a tapier 54 which is of similar construction to the rapier 14. It will be appreciated, that the driving mechanism for the rapier 54 is similar to that for the rapier 14, and is adapted to produce rectilinear reciprocation of the rapier 54 to bring the gripper 50 from a position outside the reedspace at the weft supply end of the loom, to the changeover position at approximately the centre of the reedspace.

The giver gripper 50 has a bottom jaw 56 and a co-operating top jaw 58, but unlike the taker gripper both these jaws are articulated. The bottom jaw 56 is pivoted on the giver body 52 at 60 and at its front end, it has a jaw pad 62 for engagement with the weft yarn. As illustrated in Figure 2, the bottom jaw 56 is in a closed position, and it has a tail 64 formed with a neb 66, which can be engaged by the upright portion of a catch 68 pivoted to the gripper body at 70 when the bottom jaw is in the closed position. The catch 68 is identical with the catch 32 described with reference to Figure 1, and is adapted to hold the bottom jaw 56 in the closed position against the action of resilient loading acting on the bottom jaw, which tends to turn that jaw in an anticlockwise direction as illustrated, into an open position where its front end is moved downwardly away from the top jaw.The loading of the bottom jaw 56 may be by means of a spring such as a torsion spring, or by the distribution of the weight of the bottom jaw about its pivotal axis.

The catch 68 has a generally horizontally directed arm 72, and there is a second electromagnet let into the sley of the loom, the arrangement being such, that the arm 72 is immediately over this second electro-magnet, when the gripper 50 is arrested in the changeover position during the loom cycle. The second electro-magnet is also connected in the electrical control circuit, and is adapted to be energised in similar fashion to the first electro-magnet, at an appropriate time in the loom cycle, as will appear hereinafter.

The top jaw 58 of the giver gripper 50 is pivoted to the gripper body at 74, and at its front end is provided with a pad 76 which engages with the pad 62 on the bottom jaw 56, when the top jaw is in the closed position as illu6trated. Apart from the opening of the jaws 56 and 58 which can take place due to downward movement of the front end of the jaw 56, it is also possible to open the two jaws on the giver gripper, by turning the top jaw 58 in a clockwise direction about its axis 74.Thus, even if the bottom jaw 56 is in the closed position, if the top jaw is turned to the open position, it is possible to use the giver gripper, to seize a selected weft yarn between its jaws, on the inward movement of the rapier 54 during the loom cycle. The top jaw 58 is resiliently loaded by a torsion spring not shown, into the closed position, and it has a lateral extension which projects through an opening 78 in the giver gripper body, there being a cam follower 80 on this extension, located outside the gripper body.The cam follower 80 is aligned with a stationary cam (not shown) on the loom outside the reedspace at the weft supply end of the loom, and the arrangement of this cam is such that as the gripper 50 passes underneath it, the cam follower is depressed, turning the top jaw 58 in a clockwise direction about its pivot, into the open position. The lateral extension which carries the cam follower 80 overlies the tail 64 of the bottom jaw 56, and its construction is such, that even when the bottom jaw 56 is in its open position, where its tail 64 is raised from the position illustrated, and the top jaw in its closed position, there is still a gap between the tail 64 and the lateral extension on the top jaw. Thus, during an initial part of the opening movement of the top jaw, there is no contact between the lateral extension and the tail 64, but during the later part of this opening movement, the lateral extension on the top jaw presses on the tail of the bottom jaw, and turns the bottom jaw against its spring loadong, into the closed position, where its tail is latched by the catch 68. A fixed stop is provided on the body 52, for engagement by the top jaw to restrict turning motion of the top jaw in an anticlockwise direction, and this stop is arranged to permit a very slight motion of the top jaw downwardly with the bottom jaw, when the bottom jaw is opening, but the stop does not allow the top jaw to follow the bottom jaw down into its open position.The reason why this stop permits a slight downward motion of the top jaw, is to ensure that the two jaws are firmly held together, when the bottom jaw is in the raised closed position, and the top jaw is turned under its spring loading into the closed position. Effectively however, the top jaw is prevented from turning by any substantial amount in an anticlockwise direction, beyond the closed position illustrated.

The complete cycle of operation of the loom can now be described. At the commencement of the cycle, it is assumed that the giver gripper 50 has already gripped a weft yarn in the jaws 56 and 58, and is entering the shed at the weft supply end. The jaws 56 and 58 are then in the position shown in Figure 2, that is to say the bottom jaw is locked by the catch 68 in the closed position, and the top jaw is spring loaded against the bottom jaw. At the same time, the taker gripper 10 will be entering the shed from the opposite end of the loom.

The driving mechanisms of the two rapiers are such, that the taker gripper 10 reaches its inward limit of movement at the changeover position before the giver gripper 50 arrives at the inward limit of its motion, and the arm 36 of the catch 32 is located over the first electromagnet in the loom sley.

Immediately after this, the giver gripper 50 arrives at the inner limit of its motion, with the jaws 56 and 58 still closed and at this point in the loom cycle, the jaws of the giver gripper hold the weft yarn in the then open jaws 16 and 22 of the taker gripper. It is significant that the taker gripper has already been arrested relatively to the sley when the giver gripper arrivers, as this assists in the proper positioning of the weft yarn between the jaws of the taker gripper.

The first electro-magnet is energised, tripping the catch 32 on the taker gripper, and as a result, the jaw 22 closes on to the jaw 16, nipping the weft yarn in the jaws of the taker gripper. At this point in the loom cycle therefore, the weft yarn is held by both grippers, and again it is a significant feature of the invention that this takes place, as it ensures that the weft yarn is at no time out of control.

The second electro-magnet is then energised, tripping the catch 68, and releasing the bottom jaw 56 of the giver gripper. That jaw then turns into the open position, thus releasing the hold of the giver gripper on the weft yarn. As previously explained, the top jaw 58 does not follow the bottom jaw 56 substantially, in its downward motion.

Both grippers then begin to move out of the warp shed, and since the giver gripper has completely released its hold on the weft yarn, the weft is pulled by the taker gripper out of the opposite end of the shed from that which it entered.

When the giver gripper arrives outside the warp shed at the weft supply end of the loom, the stationary cam actuates the top jaw 58, which is turned into a fuily open position, and as previously explained, this has the effect of turning the bottom jaw 56 up into the closed position, where it is latched by the catch 68. At the other end of the loom, a stationary cam actuates the top jaw 22 of the taker gripper 10, moving that jaw into the open position and latching it on the catch 32, thus releasing the weft.

A fresh weft yarn is then selected by the weft selection mechanism, and presented in the path of movement of the giver gripper 50. The latter then begins to move inwardly, so that the newly selected weft yarn is placed between its open jaws 56 and 58, and as the follower 80 moves on the cam, the jaw 58 closes on to the jaw 56, nipping the fresh weft yarn. This is the position at which the cycle just described commenced and a fresh loom cycle then begins.

Claims (23)

1. A method of weaving in a giver and taker type gripper loom, in which the jaws of a gripper are caused to open and close, as part of the weft change over operation, by energisation of electromagnet means disposed outside the warp shed, the electro-magnet means activating a catch on the gripper.

2. A method of weaving as claimed in Claim 1, in which both the giver and taker grippers are activated by the electro-magnet means.

3. A method of weaving as claimed in Claim 2, in which the giver and taker grippers are activated by separate electro-magnets and the grippers are activated successively, so that the taker gripper grips the weft thread before the giver gripper releases it, so that for a short period during changeover, the weft thread is held in both grippers.

4. A method of weaving as claimed in any one of Claims 1 to 3, in which the taker gripper arrives at the inward limit of its movement before the giver gripper arrives at the inward limit of its movement, so that the taker gripper is stationary relatively to the loom sley at the instant when the giver gripper presents the weft to the jaws of the taker gripper.

5. A method of weaving as claimed in any one of Claims 1 to 4, in which the electro-magnetic means are energised in synchronism with the loom cycle.

6. A method of weaving in a giver and taker type gripper loom substantially as herein described with reference to the accompanying drawings.

7. A gripper for use in a giver and taker type gripper loom having an articulated jaw biased into one of its open and closed positions, and catch means for retaining the articulated jaw in the other of its open and closed positions against the biasing force, the catch means being adapted to be released by magnetic means located outside the gripper to allow the articulated jaw to move under the biasing into the open or closed position.

8. A giver gripper for use in a gripper type loom having a pair of weft gripping jaws both of which are articulated on the gripper body, the first being biased into the closed position and the second being biased into the open position, there being catch means adapted to hold the second jaw in the closed position, the catch means being arranged to be released by co-operating magnetic means on the loom so that the second jaw is allowed to open when the catch is released by the magnetic means.

9. A giver gripper as claimed in Claim 8, in which the first jaw has a cam follower adapted when engaged by a cam on the loom, to cause the first jaw to move into the open position.

10. A giver gripper as claimed in Claim 8 or Claim 9, in which the first jaw has a lost motion connection with the second jaw whereby the later part of movement of the first jaw in the opening direction causes the second jaw to be moved into its closed position and engages the catch means with the second jaw.

11. A giver gripper as claimed in any one of Claims 8 to 10, in which the catch means is self latching.

12. A giver gripper as claimed in Claim 11, in which the catch means takes the form of a springloaded catch which allows a neb of the second jaw to pass it in the closing direction of movement of the second jaw, but then engages with the neb and prevents return movement of the second jaw towards the open position.

13. A giver gripper as claimed in any one of Claims 8 to 12, in which either or both of the jaws are biased by gravity or by spring loading.

14. A giver gripper as claimed in any one of Claims 8 to 13, in which there are stop means on the gripper engageable by the first jaw to prevent the latter moving with the second jaw when the second jaw moves to its open position, but the stop means is located so that it permits a small increment of movement of the first jaw with the second jaw to ensure that the stop does not prevent firm closure of the jaws in the closed position.

1 5. A giver gripper for use in a gripper type loom constructed, arranged and adapted to operate substantially as herein described with reference to Figure 2 of the accompanying drawings.

1 6. A taker gripper for use in a gripper type loom having a stationary jaw and a pivoted jaw the latter being resiliently loaded into the closed position but having a follower adapted to engage with a stationary cam on the loom to move the jaw to the open position, there being a catch adapted to retain the pivoted jaw in the open position and being further adapted to be released by magnetic means on the loom sley.

17. A taker gripper as claimed in Claim 16, in which the catch is self latching.

18. A taker gripper as claimed in Claim 17, in which the catch means takes the form of a springloaded catch which allows a neb of the second jaw to pass it in the closing direction of movement of the second jaw, but then engages with the neb and prevents return movement of the second jaw towards the open position.

19. A taker gripper for use in a gripper type loom constructed, arranged and adapted to operate substantially as herein described with reference to Figure 1 of the accompanying drawings.

20. A loom having a gripper as claimed in Claim 7.

21. A loom having a giver gripper as claimed in any one of Claims 8 to 15.

22. A loom having a taker gripper as claimed in any one of Claims 16 to 19.

23. A loom having a giver gripper as claimed in any one of Claims 8 to 15 and a taker gripper as claimed in any one of Claims 16 to 19.