Carrying gripper for looms

Abstract

 A carrying gripper presenting a gripper body (3) in turn presenting, on one side, a deflecting seat (5) for a weft yarn (11), and, on the opposite side, a gripping element (6) for maintaining crosswise to the gripper body the yarn portion extending between the deflecting seat and the gripping element. To ensure the yarn portion between the deflecting seat and the gripping element is maintained correctly positioned at all times, the deflecting seat (15) is defined, in the traveling direction of the carrying gripper, by an edge (17b) having a tangent perpendicular to the direction of the yarn upstream from the gripper. The seat is formed by a recess (8) in turn formed in a tab (7) of the gripper metal, which tab is so bent that the recess correctly guides the weft during exchange, and keeps the yarn taut even when the increase in length of the yarn is such as to cause it to slip out of the seat.

Description

[0001] The present invention relates to a carrying gripper for looms.

[0002] As is known, on modern looms, the weft yarn is inserted inside the shed, formed by the heddles, using a carrying and a drawing gripper, which travel back and forth inside the shed in a crosswise direction to the warp yarns; the carrying gripper picking up the weft yarn from the reel and carrying it roughly halfway along the shed to the so-called "exchange point", and a hook portion of the drawing gripper picking up the yarn from the carrying gripper at the exchange point and drawing it to the end of the shed where it is released from the drawing gripper.

[0003] The carrying gripper is elongated in shape and presents, on one longitudinal side, a seat for deflecting the yarn wound off the reel, and, on the other longitudinal side, a gripping element for retaining the yarn as the carrying gripper travels from one end of the loom to the exchange point. Before being gripped, the yarn therefore extends crosswise to the carrying gripper, and, as the gripper travels along the shed, the yarn extends substantially lengthwise of the gripper between this and the reel, and is deflected by said seat to the gripping element in a crosswise direction to the gripper to enable it to be picked up by the drawing gripper at the exchange point.

[0004] To ensure troublefree engagement of the yarn by the hook portion of the drawing gripper at the exchange Point, the yarn portion between the deflecting seat and the gripping element must be maintained sufficiently straight and taut at all times. When the tension of the yarn slackens, however, due to inversion of the carrying gripper or other reasons, the yarn slips out of the seat and normally assumes a compressed, e.g. coiled, configuration. As a result, at the exchange point, where the carrying gripper is decelerated and arrested sharply, the yarn portion between the reel and the gripper continues traveling by force of inertia, thus impairing the straightness and hence correct engagement by the drawing gripper of the crosswise portion of the yarn.

[0005] Yarn exchange is especially critical on modern looms in view of the high output rates and operating speeds involved.

[0006] By way of a solution to the problem, a brake is currently provided downstream from the reel, for tensioning and keeping the yarn taut in the correct exchange position. Such constant tensioning of the yarn, however, results in added stress and increases the likelihood of the yarn breaking.

[0007] It is an object of the present invention to provide a straightforward, low-cost carrying gripper designed to overcome the aforementioned drawbacks, and which in particular provides for maintaining the yarn in the correct position for pickup by the drawing gripper despite sharp deceleration during exchange and without excessively tensioning the yarn.

[0008] According to the present invention, there is provided a carrying gripper for looms, comprising a gripper body in turn presenting, on one side, a seat for a weft yarn, and, on the opposite side, a gripping element for maintaining crosswise to said gripper body the weft yarn portion extending between said seat and said gripping element; characterized in that said seat is defined, in the traveling direction of said carrying gripper, by an edge having a tangent crosswise to the direction of the yarn upstream from the carrying gripper.

[0009] More specifically, the edge defining the seat is perpendicular to the direction of the yarn upstream from the carrying gripper, so as to form a stop for arresting the yarn as it increases in length by force of inertia upon sharp deceleration of the carrying gripper and in particular when the yarn is exchanged.

[0010] According to a preferred embodiment, the seat is located at the end of a shaped recess in a tab on the gripper body, the recess presenting an inlet portion and a curved portion narrowing from the inlet portion towards the yarn deflecting seat.

[0011] The tab is formed by a projecting sheet metal portion of the gripper body, which is so bent that a guide portion, whose bottom edge defines the curved portion of the recess, projects downwards and outwards of the carrying gripper. As such, the bottom edge of the guide portion is so oriented as to feed the yarn towards the inlet of the hook portion of the drawing gripper even in the event of the yarn so increasing in length as to slip out of the deflecting seat and along the guide portion.

[0012] A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

Figures 1, 2 and 3 show side views of the carrying gripper according to the present invention in three different operating positions;

Figure 4 shows a partial top plan view of the Figure 1 gripper;

Figure 5 shows a cross section of the gripper along line V-V in Figure 3.

[0013] Number 1 in Figures 1 to 3 indicates a carrying gripper for a known loom (not shown) and designed to cooperate with a drawing gripper 2. Carrying gripper 1 comprises an elongated gripper body 3 formed by blanking and bending sheet metal and which, close to one end 4, presents a yarn deflecting seat 5 and a gripping element 6.

[0014] More specifically, close to end 4, gripper body 3 presents a curved tab 7 projecting from bottom 15 of the gripper and bent upwards at roughly a right angle (Figure 5 section).

[0015] Tab 7 presents a recess 8 forming seat 5, and, according to the present invention, recess 8 is so shaped as to define a wide lead-in portion 9 for assisting initial pickup of yarn 11 close to the end of the loom (not shown). Blending with lead-in portion 9, recess 8 presents a curved portion 12 narrowing as of lead-in portion 9 and with its convexity facing bottom 15 of gripper body 3. Curved portion 12 terminates at seat 5 where it forms two opposite edges 17a and 17b which, as shown particularly in Figure 4, present a tangent substantially perpendicular to the longitudinal direction of gripper body 3 and hence to the direction of yarn 11 upstream from gripper 1.

[0016] As shown, particularly in Figures 4 and 5, tab 7 is so bent as to form a curved first portion 18 extending from bottom 15 of gripper 1 and oppositely curved in relation to hook portion 19 of drawing gripper 2 so as to correctly guide gripper 2 during exchange; and a top portion 21 bent upwards in relation to curved portion 18.

[0017] As illustrated, curved portion 12 of recess 8 defines the bottom of a portion 22 of curved portion 18, so that portion 22 is substantially semicircular and extends from top portion 21 towards bottom 15 and outwards of carrying gripper 1 so as to appropriately orient its bottom edge 23 as explained in more detail later on.

[0018] Gripping element 6 of carrying gripper 1 is formed in known manner on the opposite longitudinal side of the gripper to that presenting tab 7, and more specifically on the underside with respect to bottom 15 of gripper body 3. Gripping element 6 substantially comprises a locating wall 24, and an elastic element 25 fitted to gripper body 3 and pressing elastically against locating wall 24. An appropriately shaped lead-in element 27 is provided in known manner for assisting insertion of the yarn between wall 24 and elastic element 25.

[0019] Also illustrated are a brake 29, and a reel 28 from which yarn 11 is unwound.

[0020] In actual use, gripper 1 therefore picks up yarn 11 at one end of the loom by means of lead-in portion 9 of recess 8 and lead-in element 27; and, as gripper 1 moves forward, yarn 11 is guided inside recess 8 into the correct position inside seat 5.

[0021] At this stage, yarn 11 rests against edge 17a where it is bent crosswise through gripper body 3 (Figure 4) up to gripping element 6; and even if the yarn continues moving forward by force of inertia when gripper 1 is decelerated sharply to a halt during exchange, the yarn portion between seat 5 and gripping element 6 remains correctly positioned. This is achieved by virtue of edge 17b being substantially perpendicular to the portion of yarn 11 extending upstream from seat 5, so that, on edge 17b first being contacted, the extra length of yarn is absorbed predominantly upstream from seat 5 as shown in Figure 2, so that the yarn portion between seat 5 and gripping element 6 remains substantially unaffected, and yarn 11 is correctly positioned for pickup by hook portion 19 of drawing gripper 2.

[0022] As such, the loom may be operated with a very low tension of yarn 11, thus reducing the probability of the yarn breaking, and also eliminating the need for painstaking, time-consuming adjustment of brake 29.

[0023] Even in the event of yarn 11 increasing in length to such an extent that edge 17b is no longer capable of retaining it inside seat 5, the shape and orientation of edge 23 are such as to guide the yarn into a position adjacent to the inlet of hook portion 19 of drawing gripper 2 and so still assist exchange by preventing an increase in the length of the yarn portion between recess 8 and gripping element 6 (Figure 3).

[0024] Clearly, changes may be made to the gripper as described and illustrated herein without, however, departing from the scope of the present invention.

Claims

1. A carrying gripper for looms, comprising a gripper body in turn presenting, on one side, a seat for a weft yarn, and, on the opposite side, a gripping element for maintaining crosswise to said gripper body the weft yarn portion extending between said seat and said gripping element; characterized in that said seat is defined, in the traveling direction of said carrying gripper, by an edge having a tangent crosswise to the direction of the yarn upstream from the carrying gripper.

2. A carrying gripper as claimed in Claim 1, characterized in that said edge presents a tangent substantially perpendicular to said direction of the yarn upstream from the carrying gripper.

3. A carrying gripper as claimed in Claim 1 or 2, characterized in that said seat is formed by a recess formed in said gripper body and presenting a wide inlet portion blending with a curved portion narrowing as of said inlet portion and towards said seat.

4. A carrying gripper as claimed in Claim 3, characterized in that said curved portion presents its convexity facing the bottom surface of the carrying gripper.

5. A carrying gripper as claimed in one of the foregoing Claims, characterized in that said gripper body is made of bent sheet metal; and said recess is formed in a tab of the sheet metal of said gripper body; said tab being bent roughly at a right angle in relation to the bottom side of said gripper body.

6. A carrying gripper as claimed in Claimed 5 and cooperating with a drawing gripper presenting a hooked end portion; characterized in that said tab comprises a curved portion presenting a curvature substantially opposite that of the hooked end portion of said drawing gripper.

7. A carrying gripper as claimed in Claim 5 or 6, characterized in that said tab comprises a guide portion defined at the bottom by said recess by means of a curved guide edge with its convexity facing said bottom side; said guide portion projecting towards said bottom side and outwards of the carrying gripper.

8. A carrying gripper as claimed in Claim 7, characterized in that said guide portion is formed in said curved portion and blends at the top with a portion bent upwards in relation to said curved portion.

Drawing