EP2194176B1

EP2194176B1 - Pile fabric loom having pile warp tension adjuster

Info

Publication number: EP2194176B1
Application number: EP20090177193
Authority: EP
Inventors: Yoshimi Iwano; Yasutaka Murakami; Yosuke Sakai
Original assignee: Toyota Industries Corp
Current assignee: Toyota Industries Corp
Priority date: 2008-12-08
Filing date: 2009-11-26
Publication date: 2013-06-05
Anticipated expiration: 2029-11-26
Also published as: EP2194176A3; EP2194176A2; JP2010133065A; JP4840735B2; CN101748552B; CN101748552A

Description

BACKGROUND OF THE INVENTION

The present invention relates to a pile fabric loom having a pile warp tension adjuster according to the preamble of claim 1, the features of which are known from document EP 1 154 057 A2 .
In a pile fabric loom, tension of pile warp changes and there are three main factors of tension changes. The first factor is shedding motion of the pile warp and the second factor is relative displacement between the beat-up position and the cloth fell position in the pile motion and the third factor is fast pick that is beaten up after loose pick filling for forming a pile. Although the tension changes due to the first and second factors vary occurs moderately, the tension change due to the third factor takes place momentarily and, therefore, influences the pile warp formation significantly.
To absorb such tension changes of the pile warp, various types of pile warp tension adjusters have been proposed. Japanese Unexamined Patent Application Publication No. 2004-11065 discloses a pile fabric loom, wherein a downwardly-extending tension lever is fixed to a support shaft that is located below a pile warp beam, a terry motion roll is fixed to the lower end of the tension lever, and the terry motion roll includes a bar extending in the direction of weaving width of the loom and a tubular spring member made of a metal sheet provided on the bar. The support shaft of the tension lever is connected to a servomotor or any other drive mechanism through gears and provides the terry motion roll with positive easing motion thereby to absorb the tension change due to the aforementioned second factor. Due to the inertia of the terry motion roll during the positive easing motion, delayed and/or overrunning movement of the terry motion roll occurs, so that tension of the pile warp changes rapidly. In the pile fabric loom according to the Publication No. 2004-11065, however, the terry motion roll itself is elastically deformed thereby to change the length of the path of the pile warp, which prevents the tension of the pile warp from changing rapidly.
Japanese Unexamined Patent Application Publication No. 52-124970 discloses an apparatus, wherein a downwardly-extending support arm is fixed to a mounting shaft that is located below a pile warp beam, a terry motion roller is mounted to the lower end of the support arm, and a leaf spring with a guide roller and a rigid guide bar is mounted to a support member fixed to the mounting shaft. Pile warp yarns turned around the guide roller are guided by the guide bar and reach the terry motion roller. The mounting shaft is positively rotated in synchronization with the relative displacement between the beat-up position for forming a pile and the cloth fell position, and provides the guide roller, the guide bar and the terry motion roller with positive easing motion. Thus, the tension change due to the second factor is absorbed. In the Publication No. 52-124970 , when the loom is operated at a high speed, rapid movement of the cloth fell position in absorbing the tension change due to the second factor causes an impact to the terry motion roller. According to the Publication No. 52-124970 , the impact to the terry motion roller is lessened by the deflection of the guide bar supported by the leaf spring.
Japanese Unexamined Patent Application Publication No. 10-60753 discloses an apparatus, wherein a fixed guide roller and a terry motion roller to which positive easing motion is provided are located below the pile warp beam, and a rigid guide bar is located between the guide roller and the terry motion roller. The guide bar is held at one end of a leaf spring which is fixed to the frame of the loom, and is operable to be displaced when the tension is applied to the pile warp. Although not described in the Publication No. 10-60753 , it is considered that the tension changes of the pile warp due to the first through third factors are absorbed by the positive easing motion of the terry motion roller and the negative easing motion due to the elastic displacement of the guide bar (actually the leaf spring).
In the pile fabric loom disclosed in the Publication No. 2004-11065 , since the terry motion roll formed by the tubular leaf spring is accelerated or decelerated by positive easing motion, the leaf spring for use needs a high strength and a large weight. If such a leaf spring is used, the inertia of the leaf spring is increased. The increased inertial force acting on the leaf spring causes an abnormal deformation to the leaf spring, and abnormal operation such as overrunning occurs easily. Consequently, absorption of the tension change due to the second factor is not accomplished sufficiently and, therefore, the pile warp tension is not sufficiently stabilized. Especially large change of pile warp tension occurring momentarily during fast picking for forming a pile due to the third factor cannot be absorbed because of the abnormal change of the leaf spring caused by the inertia. As a result, the tension of the pile warp is not kept stabilized. In addition, the abnormal change of the leaf spring due to the inertia causes a tight pick of pile easily, which deteriorates the quality of the woven cloth. Further, since area of contact of the pile warp with the terry motion roll is small, the pile warp tends to be easily spaced away or brought into contact with the terry motion roll due to the tension change, so that rolling of the pile warp occurs easily. Such rolling of the pile warp makes it difficult to absorb the tension changes due to the first through third factors.
In the apparatus of the Publication No. 52-124970 , the terry motion roller is formed by a rigid roller, the function of the leaf spring of the terry motion roll of the Publication No. 2004-11065 is separated from the terry motion roller, and a guide bar mounted on the distal end of the leaf spring is provided independently at a position adjacent to the guide roller. However, the terry motion roller, the guide bar and the guide roller are formed so as to accomplish positive easing motion. Therefore, a large inertial force acts on the guide bar having a large mass. As in the case of the Publication No. 2004-11065 , the tension change of the pile warp fails to be absorbed sufficiently and, therefore, the quality of the woven cloth deteriorates. In addition, because the area of contact of the pile warp with the guide bar is small, rolling of the pile warp occurs and the absorption of the tension change deteriorates as in the case of the Publication No. 2004-11065 .
The guide bar of the Publication No. 10-60753 which is formed so as to absorb the tension change of the pile warp by negative easing motion solves the problem of the inertial force which is caused by positive easing motion as in the case of the Publications Nos. 2004-11065 and 52-124970 . However, the guide bar formed of rigid body has a large mass. Therefore, when the momentary tension acts on the pile warp as in the case of the tension change due to the third factor, the guide bar is displaced due to its own inertial force without responding to the tension change. As a result, the function of absorbing the tension change deteriorates. In addition, since the area of contact of the pile warp with the guide bar is small, rolling of the pile warp occurs and function of absorbing the tension change deteriorates as in the case of the Publications Nos. 2004-11065 and 52-124970 .
The present invention is directed to a pile fabric loom having a pile warp tension adjuster, wherein the tension change of pile warp yarn, including a momentarily increasing tension occurring during fast picking for forming a pile, is absorbed sufficiently and a stabilized warp yarn tension is maintained.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a pile fabric loom that includes a frame, a pile warp beam, a terry motion roller and a pile warp tension adjuster. The pile warp beam is supported by the frame. The terry motion roller serves to guide pile warp yarns let off from the pile warp beam toward cloth fell. The pile warp tension adjuster is operable to adjust tension of the pile warp yarns. The pile warp tension adjuster has a leaf spring that is located along a path of the pile warp yarns extending from the pile warp beam to the terry motion roller. The leaf spring extends in longitudinal direction of the loom. The leaf spring has in the longitudinal direction of the loom a first end and a second end. The first end is fixed to the frame. The surface of the second end is in contact with the pile warp yarns. The leaf spring is elastically deformable by the tension of the pile warp yarns. The pile warp tension adjuster further has a guide plate as defined in claim 1.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

Fig. 1 is a schematic view showing a pile fabric loom according to a preferred embodiment of the present invention;
Fig. 2 is a side view showing a pile warp tension adjuster of the pile fabric loom of Fig. 1;
Fig. 3 is an exploded perspective view showing the pile warp tension adjuster of Fig. 2; and
Fig. 4 is an exploded view showing the pile warp tension adjuster as taken along the line 4-4 of Fig. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following will describe the pile fabric loom according to the preferred embodiment of the present invention with reference to Figs. 1 through 4. The pile fabric loom will be referred to merely as a loom hereinafter. It is noted that the right-hand side and the left-hand side of the loom as viewed in Fig. 1 correspond to the front direction and the rear direction of the loom (the longitudinal direction), respectively. Referring to Fig. 1 showing schematically the loom in its side view, the loom has a ground warp beam indicated generally by reference numeral 1. The ground warp beam 1 is driven to rotate by a let-off motor Mg connected electrically to first let-off controller C1. Ground warp yarns T which are let off from the ground warp beam 1 by the operation of the let-off motor Mg and moved past an arched back guide plate 2 and a tension roller 3 and passed through the heddles 4 and the reed 5. The woven cloth W is taken up around the cloth roller 10 via an expansion bar 6, a surface roller 7, guide rollers 8 and 9.
The frame 11 of the loom supports the back guide plate 2 through a bracket (not shown) fixed to the frame 11 by bolts (not shown) and also supports a support shaft 12 rotatably. An upper arm 13 is fixed to the support shaft 12 and the tension roller 3 is rotatably supported by the upper arm 13 at the upper end thereof. The tension roller 3 is urged by any suitable urging mechanism (not shown) and absorbs tension change of the ground warp yarns T due to shedding motion by negative easing motion. The lower arm 14 is fixed to the support shaft 12 and a rod 15 is connected rotatably to the lower end of the lower arm 14.
A load cell 16 is mounted on the rod 15 for detecting the tension of ground warp yarns T acting on the tension roller 3, and connected electrically to the first let-off controller C1. The first let-off controller C1 is operable to control the speed of the let-off motor Mg based on a preset reference tension and information of warp yarn tension detected by the load cell 16.
A pile warp beam 17 is located above the ground warp beam 1. The pile warp beam 17 is driven to rotate by a let-off motor Mp connected electrically to the second let-off controller C2. The pile warp yarns Tp that are let off from the pile warp beam 17 and moved past a guide roller 18, a pile warp tension adjuster 19 and a terry motion roller 20 are passed through the heddles 4 and the reed 5. The pile warp tension adjuster 19 is operable to adjust the tension of pile warp yarns Tp.
The guide roller 18 is fixed to the frame 11 at a position below the pile warp beam 17. The guide roller 18 has a pair of elements (not shown) to be detected at the ends thereof where the pile warp yarns Tp are not guided. A pair of proximity switches 21 (only one being shown) is located in facing relation to the above paired elements to be detected. The paired proximity switches 21 serve to detect the rotation of the guide roller 18 and also to send the detection signal to the second let-off controller C2.
The tension adjuster 19 is located below and adjacent to the guide roller 18, and will be described with reference to Figs. 2 through 4, in which the tension adjuster 19 is shown enlarged. As shown in the exploded views of Figs. 3 and 4, the tension adjuster 19 includes a support shaft 22, a spacer 23, a guide plate 24, a leaf spring 25, a nut bar 26 and a fixed bar 27. The guide plate 24 is divided into a plurality of plate members.
The support shaft 22 extends in the direction of weaving width of the loom and is supported at the opposite ends thereof in the frame 11 by a holder 28 (refer to Fig. 3) and a bolt 29. A plurality of retainer rings 30 is fixedly fitted on the support shaft 22 by any suitable means. A hook-shaped retainer bracket 31 having a vertical portion 32 is fixed to each retainer ring 30 by means of bolts (not shown) passed through bolt holes 33 bored through the vertical portion 32 of the retainer bracket 31 and bolt holes 30A bored through the retainer ring 30.
The retainer bracket 31 has a horizontal portion 34 that is connected perpendicularly to the vertical portion 32 and has therethrough a bolt hole 36 for receiving therethrough a bolt 35. The spacer 23 which is formed by a bar having a rectangular cross section extends in the direction of weaving width. The spacer 23 has therethrough a plurality of vertical bolt holes 37. The bolt holes 37 correspond to the respective bolt holes 36 of the horizontal portions 34 of the retainer brackets 31.
The guide plate 24 includes plural plate members made of rigid material and aligned in the direction of weaving width. The guide plate 24 is formed so that its distal end 38 extending in the rear direction of the loom (or to the left side in Fig. 1) is curved downward, as shown in Fig. 4. That is, the guide plate 24 is curved convexly toward the leaf spring 25. As shown in Figs. 3 and 4, the guide plate 24 is formed so that the proximal end 39 of each plate member of the guide plate 24 on the side of the front of the loom (or the end on the right side in Fig. 1) has at positions corresponding to the bolt holes 36, 37 three grooves 40. Each groove 40 has a size that is large enough for the bolt 35 to be received through the groove 40.
The leaf spring 25 is located along the path of the pile warp yarns Tp. The leaf spring 25 is formed by a thin elastic member having substantially the same length as the spacer 23 extending in the direction of weaving width for a length corresponding to the width of the sheet of pile warp yarns Tp guided by the guide roller 18. The leaf spring 25 is located with its short side length extending in the longitudinal direction of the loom. As viewed in the crosswise direction of the loom, the leaf spring 25 is longer than the guide plate 24. As shown in Fig. 4, the distal end 41 of the leaf spring 25 extending in the rear direction of the loom (or to the left side in Fig. 4) is formed so as to be bent downward in the form of a hook. The leaf spring 25 has at the proximal end 42 thereof at positions corresponding to the bolt holes 36, 37 a plurality of grooves 43, as in the case of the guide plate 24. Each groove 43 has a size that is large enough for the bolt 35 to be received through the groove 43. The guide plate 24 is spaced away from at least a side of the distal end 41 of the leaf spring 25 in a direction in which the leaf spring 25 is deformed elastically by tension of the pile warp yarns Tp.
The nut bar 26 is formed by a bar having substantially the same length as the leaf spring 25 extending in the direction of weaving width and a quadrangular cross section. The nut bar 26 has therethrough at positions corresponding to the bolt holes 36 and 37 a plurality of screw holes 44 for receiving therethrough each bolt. The fixed bar 27 having a bottom 45 is formed by a tubular bar having therein a plurality of hollow portions. The fixed bar 27 has a relatively small front hollow portion 46 formed on the front side and a relatively large hollow portion 47 formed on the rear side, respectively. As shown in Fig. 4, the hollow portions 46 and 47 have different height dimensions as measured from the bottom 45. The hollow portion 46 has a space that is large enough to receive therein the nut bar 26. The bottom 45 has a dovetail groove 48 formed therethrough in the direction of weaving width of the loom at position corresponding to the screw holes 44. Each dovetail groove 48 is formed large enough to receive therein the bolts 35. The fixed bar 27 has on the top surface thereof for the hollow portion 47 a guide surface 49 that is curved downward.
The tension adjuster 19 may be assembled, for example, in the following manner. Firstly, the spacer 23, the proximal end 39 of the guide plate 24, the proximal end 42 of the leaf spring 25 and the bottom 45 of the fixed bar 27 are set one on another on the horizontal portion 34 of the retainer bracket 31 and the nut bar 26 is inserted into the hollow portion 46 of the fixed bar 27. Subsequently, the bolt holes 36, 37, the grooves 40, 43, the dovetail groove 48 and the screw hole 44 are aligned with each other and the bolt 35 is inserted through the aligned holes and grooves and screwed securely into the screw hole 44 of the nut bar 26. Thus, the tension adjuster 19 is assembled into a unit. Then, the bolt holes 33 in the vertical portion 32 of the retainer bracket 31 are aligned with the bolt holes 30A of the retainer ring 30, and bolts (not shown) are inserted through the aligned holes and tightened, thus the tension adjuster 19 being mounted on the support shaft 22. The tension adjuster 19 is operable by negative easing motion using the deflection of the leaf spring 25 to absorb tension change of pile warp yarn Tp due to warp shedding motion and also tension change caused by fast pick for forming a pile.
As shown in Fig. 2, a horizontally extending lever 50 is fixed to the support shaft 22, and another lever 52 having a load cell 51 is connected at one end thereof to the lever 50 and fixed at the other end thereof to the frame 11. The load cell 51 is operable to detect the tension of pile warp yarn Tp in response to a variation of load acting on the support shaft 22 through the leaf spring 25 and to generate a detection signal to the second let-off controller C2. The second let-off controller C2 controls the speed of the let-off motor Mp based on the comparison of the tension detection information obtained from the load cell 51 with the preset reference tension and on the rotation detection signal obtained from the proximity switch 21 (refer to Fig. 1).
As shown in Figs. 1 and 2, a swing lever 54 having an upper arm 55 is rotatably supported by the shaft 53 and has at the distal end of the upper arm 55 a holding portion 56 having a U-shaped cross section. The holding portion 56 has an arched surface whose radius of curvature is slightly smaller than the radius of the terry motion roller 20 for snap-fitting of the terry motion roller 20 in the holding portion 56 of the swing lever 54. Such snap-fitting facilitates mounting and removing of the terry motion roller 20. The terry motion roller 20 is vertically spaced away far from the leaf spring 25, so that piecing operation and loom exchange operation can be easily performed. The lower arm 57 of the swing lever 54 has at the distal end thereof an elongated hole 58 and is connected rotatably to the rod 15 by a bolt 59 passed through the elongated hole 58.
As shown in Fig. 1, a forked intermediate lever 60 is pivotally mounted on the shaft 60 at an intermediate position as viewed in the longitudinal direction of the loom, and a pile motion mechanism 62 is located above the forked intermediate lever 60. Although the internal structure of the pile motion mechanism 62 is not shown, a drive unit formed by a ball screw mechanism or cam mechanism driven by its own drive motor or a loom drive motor Mo is provided in the pile motion mechanism 62. When such drive unit is operated, a drive lever 64 mounted on a drive shaft 63 that is connected to the drive unit is pivoted alternately.
The operation of the loom drive motor Mo is controlled by the loom controller Cd connected to a rotary encoder 65 that detects the angular position of the main shaft of the loom. The loom controller Cd and the second let-off controller C2 are connected to a patterning controller 66 in which pile weaving pattern is set. The patterning controller 66 sends a pile weaving pattern information to the loom controller Cd and the second let-off controller C2 at each predetermined angular position of the loom in one picking cycle. Therefore, the loom controller Cd controls the operation of the pile motion mechanism 62 based on the weaving pattern information provided from the patterning controller 66. In addition, the second let-off controller C2 controls the operation of the let-off motor Mp based on the weaving pattern information provided from the patterning controller 66.
The drive lever 64 transmits the alternate pivotal movement to the forked intermediate lever 60 through a rod 68 connected to one arm 67 of the forked intermediate lever 60. The forked intermediate lever 60 transmits the swing motion (or terry motion) to the tension roller 3 and the terry motion roller 20 through the rod 15 connected to the other arm 69 of the forked intermediate lever 60. The expansion bar 6 which guides a woven cloth W at the front of the loom is supported by the upper end of the swing lever 71 which is rotatably supported by the shaft 70. The lower end of the swing lever 71 is connected to the other arm 69 of the intermediate lever 60 through the rod 72.
Therefore, alternate pivotal movement of the intermediate lever 60 causes the swing lever 71 to swing through the rod 72 thereby to transmit to the expansion bar 6 the terry motion in the same direction as the tension roller 3 and the terry motion roller 20. The terry motion based on the weaving pattern causes the tension roller 3, the terry motion roller 20 and the expansion bar 6 to swing toward the front of the loom, or rightward in Fig. 1, during loose picking in the pile weaving operation thereby to move the cloth fell W1 to the position indicated by the dashed line in Fig. 1. The terry motion based on the weaving pattern also causes the tension roller 3, the terry motion roller 20 and the expansion bar 6 to swing toward the rear of the loom, or leftward in Fig. 1, during fast picking and border weaving in the pile weaving operation thereby to move the cloth fell W1 to the position indicated by the solid line in Fig. 1.
The following will explain the operation of the pile fabric loom of the above-described embodiment. The pile warp yarns Tp let off from the pile warp beam 17 are passed around the guide roller 18, moved past the guide surface 49 of the fixed bar 27 while being in contact therewith, and then moved past the leaf spring 25 while being in contact with the surface of the distal end 41 of the leaf spring 25. The leaf spring 25 is bent by the tension of the pile warp yarns Tp from the position of the dashed line (the position where the pile warp yarns Tp have no tension) to the position of the solid line, as shown in Fig. 2, which allows the pile warp yarns Tp to be in contact with the leaf spring 25 over a wide range. Bending of the leaf spring 25 causes a predetermined tension to the pile warp yarns Tp. The pile warp yarns Tp having moved past the leaf spring 25 are guided by the terry motion roller 20 and reaches the cloth fell W1 through the heddles 4 and the reed 5.
When the pile fabric loom is operated by starting the loom drive motor Mo with pile warp yarns Tp so set in the loom, the pile weaving operation and border weaving operation are repeated according to a predetermined picking cycle based on the pattern signal from the patterning controller 66 together with the shedding motion of the pile warp yarns Tp. In the pile weaving operation, the tension roller 3, the terry motion roller 20 and the expansion bar 6 are swung to the positions of the dashed lines of Fig. 1 by the operation of the pile motion mechanism 62 and the cloth fell W1 is moved to the position of the dashed line of Fig. 1, so that a loose pick is inserted into a shed. During fast picking following the loose picking, the tension roller 3, the terry motion roller 20 and the expansion bar 6 are swung to the positions of the solid lines of Fig. 1 by the operation of the pile motion mechanism 62. Therefore, fast picking is performed with the cloth fell W1 moved to the position of the solid line to form a pile in the woven cloth W.
The pile warp yarns Tp are moved in the longitudinal direction of the loom in accordance with the displacement of the cloth fell W1 in changing between fast picking and loose picking thereby to cause tension change. However, such tension change is absorbed by the positive easing motion of the terry motion roller 20 operating in conjunction with the pile motion mechanism 62. During the fast picking, the cloth fell W1 is displaced from the position of the dashed line to the position of the solid line in Fig. 1 for forming a pile, and strong beating is performed by the reed 5. Thus, a large tension change occurs in the pile warp yarns Tp momentarily. However, when a large tension acts on the pile warp yarns Tp momentarily, the leaf spring 25 is bent momentarily thereby to absorb the tension change occurring in the pile warp yarns Tp momentarily.
The leaf spring 25, which is formed so as to accomplish negative easing motion, does not require so much strength as compared to the case where positive easing motion is accomplished, so that thin and light material may be used for the leaf spring 25 and abnormal change due to the inertia of the leaf spring 25 itself is prevented. The bending of the leaf spring 25 occurs in quick response to the momentary tension change of pile warp yarns Tp during the fast picking, so that the tension of pile warp yarns Tp is maintained properly. In addition, a problem due to tight pick of pile is prevented, so that the quality of woven cloth is improved, The leaf spring 25 bent momentarily due to the tension change of pile warp yarns Tp during fast picking returns to its initial position gradually by the subsequent letting off of the pile warp yarns Tp. The leaf spring 25 also serves to absorb moderate tension change of pile warp yarns Tp due to the shedding motion.
The pile warp yarns Tp after being moved around the guide roller 18 are kept in contact with the guide surface 49 of the fixed bar 27 and the leaf spring 25 over a large area so as to reduce as much as possible the area where the pile warp yarns Tp are placed in free state. Therefore, rolling of pile warp yarns Tp caused by the above-described three types of tension changes is prevented, and overlapping and entanglement of pile warp yarns Tp are also prevented, with the result that the pile warp yarns Tp are placed under a stabilized tension.
It is necessary to apply a higher tension to pile warp yarns Tp during the border weaving operation than during the pile weaving operation. In addition, the time during which the pile weaving operation is changed to the border weaving operation within a normal weaving cycle during normal-speed operation of the pile fabric loom is extremely short. The leaf spring 25 which is bent by the tension of the pile warp yarns Tp in changing to the border weaving operation to a predetermined extent is gradually brought into contact with the curved surface of the guide plate 24. The leaf spring 25 is elastically deformable only at a limited region thereof in the longitudinal direction of the loom which is out of contact with the guide plate 24. Thus, the spring constant of the leaf spring 25 is increased smoothly and rapidly. Consequently, the tension of pile warp yarns Tp is increased to a necessary level in a short time, and pile fabric having clear boundary between the pile weave and the border weave is woven, accordingly. Since the guide plate 24 is formed in a curved surface, the leaf spring 25 is brought into contact with the guide plate 24 over a large area, so that vibration which may be caused by contact over a small area between the guide plate 24 and the leaf spring 25 is prevented and, therefore, the contact and entanglement between the pile warp yarns Tp are prevented.
The above-described embodiment of the present invention offers the following advantageous effects.

(1) Abnormal change of warp yarn tension due to the inertia of the leaf spring 25 itself is prevented. In addition, change of the tension occurring momentarily during fast picking is absorbed effectively.
(2) Combining the leaf spring 25 which eases the tension of pile warp yarns Tp by negative easing motion and the terry motion roller 20 which eases the tension of pile warp yarns Tp by positive easing motion, change of warp yarn tension due to the aforementioned three factors is absorbed effectively. Therefore, the pile warp yarns Tp are kept under a steady tension.
(3) The provision of the guide plate 24 in the tension adjuster 19 is effective to increase the tension of pile warp yarns Tp in a short time in changing from the pile weaving operation to the border weaving operation.
(4) The provision of the guide roller 18 enhances the degree of freedom of mounting position of the leaf spring 25, which makes it possible to ensure a large vertical space between the leaf spring 25 and the terry motion roller 20. Such space facilitates piecing operation and loom exchange operation.
(5) The leaf spring 25 which is fixed to the frame 11 is not required to have a high mechanical strength, so that the inertia of the leaf spring 25 itself can be reduced significantly. In addition, the pile warp yarns Tp are guided in contact with a large surface area of the leaf spring 25, area of contact of the pile warp Tp with the leaf spring 25 is increased. The combination of the reduced inertia force of the leaf spring 25 and the increased contact area of the pile warp yarns Tp is effective to absorb the tension change of the pile warp yarns Tp. The elasticity of the leaf spring 25 that responds to a momentary increase of tension of pile warp yarns Tp during fast picking is improved. Such absorption of the tension change of pile warp yarns Tp functions properly in a pile fabric loom operating at a higher speed.
(6) During border weaving or ground weaving which needs a high tension to pile warp yarns Tp, the contact length of the displaced leaf spring 25 with the guide plate 24 at a region adjacent to their proximal ends is increased, so that the elastically operating length of the leaf spring 25 is reduced, with the result that the spring constant of the leaf spring 25 is increased. Therefore, the tension of pile warp yarns Tp can be increased rapidly to a preset tension. In addition, the guide plate 24 which is formed with a curved surface is prevented from contacting with the leaf spring 25 at a concentrated area, which helps to prevent the leaf spring 25 from generating vibration and noise and also from damage due to contact with the guide plate 24.
(7) The pile warp tension adjuster 19 has a fixed bar 27 which is fixed to the frame 11 and holds the leaf spring 25 at its proximal end 42. The distal end 41 of the leaf spring 25 is formed with a curved surface. This structure facilitates mounting and removing of the leaf spring 25. In addition, the curved surface of the leaf spring 25 allows smooth contact of pile warp yarns Tp with the leaf spring 25.
(8) The guide plate 24 is divided into plural plate members which are located in the direction of weaving width of the loom. As compared to the case where the guide plate is formed by a single plate, the guide plate 24 of the present embodiment is advantageous in that a guide plate with high accuracy is manufactured easily. In addition, divided structure facilitates mounting and removing of the guide plate 24.

The present invention has been described in the context of the above embodiment, but it is not limited to that embodiment. It is obvious that the invention may be practiced in various manners as exemplified below.
The distal end 41 of the leaf spring 25 does not necessarily need to be formed with a curved surface.
The guide plate 24 may be formed by a single rigid plate.
The guide plate 24 may be dispensed with.
The guide surface 49 of the fixed bar 27 that guides pile warp yarns Tp may be dispensed with.
If the pile fabric loom is so arranged that the tension change of pile warp yarns Tp due to the reducing diameter of the pile warp beam 17 is absorbed by the leaf spring 25, the guide roller 18 may be dispensed with.
The tension roller 3 may be formed so as to accomplish negative easing motion.
In the above-described embodiment, the relative displacement between the cloth fell W1 and the beating position is accomplished by the displacement of the cloth fell W1. However, such relative displacement may be accomplished by the displacement of the beating position with the cloth fell W1 fixed.
By interposing a spacer between the leaf spring 25 and the guide plate 24 at the position adjacent to the proximal ends thereof, a space may be formed between the leaf spring 25 and the guide plate 24 also at their proximal ends.
A pile fabric loom includes a frame, a pile warp beam, a terry motion roller and a pile warp tension adjuster. The pile warp beam is supported by the frame. The terry motion roller serves to guide pile warp yarns let off from the pile warp beam toward cloth fell. The pile warp tension adjuster is operable to adjust tension of the pile warp yarns. The pile warp tension adjuster has a leaf spring that is located along a path of the pile warp yarns extending from the pile warp beam to the terry motion roller. The leaf spring extends in longitudinal direction of the loom and a first end and a second end. The first end is fixed to the frame. The surface of the second end is in contact with the pile warp yarns. The leaf spring is elastically deformable by the tension of the pile warp yarns.

Claims

A pile fabric loom comprising:
a frame (11);

a pile warp beam (17) supported by the frame (11);

a terry motion roller (20) for guiding pile warp yarns (Tp) let off from the pile warp beam (17) toward cloth fell (W1); and

a pile warp tension adjuster (19) being operable to adjust tension of the pile warp yarns (Tp);

characterized in that

the pile warp tension adjuster (19) has a leaf spring (25) that is located along a path of the pile warp yarns (Tp) extending from the pile warp beam (17) to the terry motion roller (20), the leaf spring (25) extending in longitudinal direction of the loom,

wherein the leaf spring (25) has in the longitudinal direction of the loom a first end (42) and a second end (41), the first end (42) being fixed to the frame (11), the surface of the second end (41) being in contact with the pile warp yarns (Tp), wherein the leaf spring (25) is elastically deformable by the tension of the pile warp yarns (Tp), wherein

the pile warp tension adjuster (19) has a guide plate (24) extending in the longitudinal direction of the loom and made of rigid material, wherein the guide plate (24) is spaced away from at least a side of the second end (41) of the leaf spring (25) in a direction in which the leaf spring (25) is deformed elastically by tension of the pile warp yarns (Tp), wherein the guide plate (24) has shorter dimension in the longitudinal direction of the loom than the leaf spring (25), wherein the guide plate (24) is curved perpendicular to the path of the pile warp yarns (Tp).
The pile fabric loom according to claim 1, characterized in that
the guide plate (24) is curved convexly toward the leaf spring (25).
The pile fabric loom according to claim 2, characterized in that
the guide plate (24) is divided into plural plate members which are aligned by the leaf spring (25) in a direction of weaving width of the loom.
The pile fabric loom according to any one of claims 1 through 3, characterized in that
the pile warp tension adjuster (19) has a fixed bar (27) which is fixed to the frame (11) and holds the leaf spring (25) at the first end (42), wherein the second end (41) of the leaf spring (25) is formed with a curved surface.
The pile fabric loom according to claim 4, characterized in that
the fixed bar (27) is located closer to the pile warp beam (17) than the curved surface of the leaf spring (25) and has a guide surface (49) in contact with the pile warp yarns (Tp).
The pile fabric loom according to any one of claims 1 through 5, characterized in that
a ground warp beam (1) is supported by the frame (11) and located below the pile warp beam (17), wherein a guide roller (18) is located below the pile warp beam (17) for guiding the pile warp yarns (Tp) let off from the pile warp beam (17), wherein the terry motion roller (20) is located below the guide roller (18) so as to be vertically spaced away from the guide roller (18) more than a distance between the guide roller (18) and the pile warp beam (17), wherein the leaf spring (25) is located closer to the guide roller (18) than to the terry motion roller (20).
The pile fabric loom according to any one of claims 1 through 6, characterized in that
the leaf spring (25) serves to ease the pile warp yarns (Tp) by negative easing motion, wherein the terry motion roller (20) serves to ease the pile warp yarns (Tp) by positive easing motion.