EP3106554B1

EP3106554B1 - Method for controlling shed opening of pile warp yarns in pile fabric loom

Info

Publication number: EP3106554B1
Application number: EP16172375.4A
Authority: EP
Inventors: Yosuke Sakai; Hiromasa Sugiyama; Yoshimi Iwano
Original assignee: Toyota Industries Corp
Current assignee: Toyota Industries Corp
Priority date: 2015-06-15
Filing date: 2016-06-01
Publication date: 2018-05-09
Anticipated expiration: 2036-06-01
Also published as: JP6269587B2; EP3106554A3; JP2017002449A; CN106245200A; EP3106554A2; CN106245200B

Description

BACKGROUND OF THE INVENTION

The present invention relates to a method for controlling the shed opening of pile warp yarns in a pile fabric loom that has a plurality of heald frames each having its own drive device and forms piles by forward and backward movement of cloth fell.
Japanese Patent Application Publication No. 2001-131845 discloses a method for controlling the tension of pile warp yarns in a pile fabric loom. According to the method, the tension of pile warp yarns in forming piles is set lower than that in normal weaving to control the tension of pile warp yarns appropriately so that piles of a desired length are formed without failure of weft insertion by inappropriate shed opening of warp yarns. In the pile fabric loom in which the method according to the above Publication is performed, a tension roller is provided in a pile warp let-off device and driven by an AC servo motor. The AC servo motor varies its output in response to an electrical signal received during the beating a weft yarn to form piles. The tension roller is moved by the AC servo motor in such direction that decreases the tension of pile warp yarns, with the result that the tension of pile warp yarns is set lower than normal during the beating of a weft yarn.
In the middle of the pile warp yarn shed opening operation, friction occurring among pile warp yarns, ground warp yarns and component parts of the loom such as a reed and a heald, causes the pile warp yarns adjacent to the passage of a weft yarn to be tensioned inadequately, so that failure of shed opening occurs. According to the method of the above Publication, while the shed opening of pile warp yarns is being increased, the AC servo motor drives the tension roller so that the tension of the pile warp yarns is higher than that during other than increasing the shed opening of the pile warp yarns. Thus, the pile warp yarns forming a shed are tensioned adequately, with the result that the separation of pile warp yarns is improved.
Japanese Patent Application Publication No. H10-130988 discloses an apparatus and method for controlling the shed opening in a pile fabric loom. According to the method, beating of a weft yarn to cloth fell is made fast so as to stabilize weft beating up operation when loom weaving operation is changed from pile weaving to border weaving and weft density in the woven fabric is increased accordingly. The pile fabric loom according to the above Publication includes a loom control computer, a patterning controller, and a shed opening controller having a shed opening curve generating circuit, a control circuit, and a drive circuit.
During weaving operation, the pattern controller transmits pattern data to the loom control computer. The loom control computer transmits data on weft yarn density included in the pattern data to the shed opening curve generating circuit. The shed opening curve generating circuit generates a changed shed opening curve in response to a signal for change of weft yarn density so that weft yarn is stably beaten and the fabric has clear boundary between weaves whose weft yarn densities are different from each other. In changing of the shed opening curve, cross points, dwell angles on the upper and lower sides, and shed opening amounts are changed selectively.
In the pile fabric loom, piles are formed by repeating of loose picking in which an inserted weft yarn is beaten at a cloth fell that is frontward of normal cloth fell position and fast picking in which an inserted weft yarn is beaten at the normal cloth fell position. Since pile warp yarns are tensioned in the loose picking by movement of the cloth fell, the loose picking does not influence the shed opening of the pile weft yarns. However, since the cloth fell is moved backward in the fast picking, the pile weft yarn may be loosened. As a result, weft insertion may fail because of the inadequate shed opening of the pile warp yarns.
The above Publication No. 2001-131845 describes a configuration in which the tension roller that controls the tension of the pile warp yarns is operated by the AC servo motor and the tension of the pile warp yarns is positively increased during the increase of the shed opening of the pile warp yarns. However, as indicated in the above Publication, the friction occurring among parts such as reed, healds, droppers, pile warp yarns and ground warp yarns is large, and the distance between the tension roller and cloth fell is long. In the pile fabric loom in which the pile warp yarns tension is lower than the ground warp yarn tension, tension is not effectively transmitted.
The tension is not sufficiently transmitted to the pile warp yarns at the cloth fell position by positive operation of the tension roller and, therefore, the problem with loosening of the pile warp yarns due to the movement of the cloth fell is not solved. Especially, because the movement of cloth fell and shed opening of the pile warp yarns in the fast picking are performed in a very short time, the tension of the pile warp yarns cannot be successfully controlled by the tension roller in the high-speed operation of the pile fabric loom.
In the above Publication No. H10-130988 , the shed opening curve is changed only when the warp yarn density is changed, or when the loom weaving operation is changed from pile weaving to border weaving. The above Publication provides no indication about the elimination of loosening of the pile warp yarns in the fast picking that is repeated for every several picking cycle to form piles.
The present invention is directed to providing a method for suppressing the decrease of tension of pile warp yarns in a fast picking in a pile fabric loom.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, there is provided a method for controlling shed opening of pile warp yarns in a pile fabric loom. The pile fabric loom includes a plurality of heald frames through which the pile warp yarns are passed, and a plurality of drive devices driving the respective heald frames and forms piles by forward and rearward movement of cloth fell. The method is characterized by setting a shed opening amount of the pile warp yarns at a start of weft insertion in fast picking larger than a shed opening amount of the pile warp yarns at a start of weft insertion in loose picking.
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 in which a method according to a first embodiment of the present invention is performed;
FIG. 2 is a chart showing shed opening curve of pile warp yarns in the pile fabric loom of FIG. 1;
FIGS. 3A, 3B, and 3C are schematic views showing loose picking and fast picking in the pile fabric loom of FIG. 1;
FIG. 4 is a chart showing shed opening curve of pile warp yarns in a pile fabric loom in which a method according to a second embodiment of the present invention is performed;
FIG. 5 is a chart showing shed opening curve of pile warp yarns in a pile fabric loom in which a method according to a third embodiment of the present invention is performed; and
FIG. 6 is a chart showing shed opening curve of pile warp yarns in a pile fabric loom in which a method according to another embodiment of the present invention is performed.

DETAILED DESCRIPTION OF THE EMBODIMENTS

First embodiment

The following will describe a pile fabric loom in which a method for controlling the shedding of pile warp yarns according to a first embodiment is performed with reference of FIGS. 1 through 3. Referring to FIG. 1, the right and the left of FIG. 1 correspond to the front and the rear of the pile fabric loom, respectively. The upper and the lower sides of FIG. 1 correspond to the upper and the lower sides of the pile fabric loom, respectively. In FIG. 1 showing the pile fabric loom in side view, a ground warp beam 1 is driven by a ground warp let-off motor M2 that is electrically connected to a ground warp let-off controller C2. Ground warp yarns TG that are let-off from the ground warp beam 1 with the rotation of the ground warp let-off motor M2 are moved through an arched back guide plate 2 and a tension roller 3 and passed through a plurality of heald frames 4A, 4B, 4C, 4D and a reed 5. Woven cloth W is moved through an expansion bar 6, a surface roller 7, and guide rollers 8, 9 and taken up by a cross roller 10.
A frame 11 of the loom supports the back guide plate 2 and rotatably supports a tension pipe 12 having an urging mechanism providing urging force to the tension roller 3. An upper support arm 13 is fixedly mounted to the tension pipe 12 and rotatably supports at the upper end thereof the tension roller 3. Tension variation of the ground warp yarn TG caused by shedding of warp yarns is absorbed by negative easing motion of the tension roller 3 urged by the urging mechanism of the tension pipe 12. A downwardly extending lever 14 is fixed to the urging mechanism of the tension pipe 12. A rod 15 is pivotally connected to the lower end of the lever 14.
A load cell 16 is mounted to the rod 15 for detecting the tension of ground warp yarns TG acting on the tension roller 3, and electrically connected to the ground warp let-off controller C2. The ground warp let-off controller C2 controls the speed of the ground warp let-off motor M2 based on a predetermined reference tension value and data of warp yarn tension detected by the load cell 16. A pile warp beam 17 is disposed above the ground warp beam 1. The pile warp beam 17 is driven by a pile warp let-off motor M3 that is electrically connected to the pile warp let-off controller C3. The pile warp yarns TP that are let off from the pile warp beam 17 are moved through a turning roller 18, a tensioning member 19 and a terry motion roller 20 and passed through the heald frames 4A, 4B, 4C, 4D and the reed 5.
The turning roller 18 is rotatably supported by a shaft 22 that is fixed to the frame 11 and having a load cell 21. The load cell 21 detects the tension of the pile warp yarns TP and transmits to the pile warp let-off controller C3 signal of the detected tension. The turning roller 18 has at the opposite ends thereof that are not in contact with the pile warp yarns TP a pair of elements (not shown) to be detected. A pair of proximity switches 23 (only one being shown) is disposed in facing relation to the above paired elements to be detected. The paired proximity switches 23 detect the rotation of the turning roller 18 and also transmit signals to the pile warp let-off controller C3. The pile warp let-off controller C3 controls the speed of the warp let-off motor M3 based on the comparison of a predetermined reference tension value and data of warp yarn tension detected by the load cell 21, and rotational signals detected by the proximity switches 23.
The tensioning member 19 is supported by a leaf spring 24 fixed to the frame 11. Tension variation of the pile warp yarns TP due to movement of the warp yarn shed opening is absorbed by negative easing motion of the tensioning member 19 due to the deflection of the leaf spring 24. In order to form piles securely in the pile fabric loom, the tension of the pile warp yarns TP is set lower than that of the ground warp yarns TG. The terry motion roller 20 is rotatably supported by the end of the upper arm of a rocking lever 26 which is pivotally supported on a shaft 25. The lower arm of the rocking lever 26 is pivotally connected to the rod 15.
A forked intermediate lever 27 is rotatably mounted on a shaft 28 at an intermediate position as viewed in the front-and-rear direction of the pile fabric loom. A pile motion mechanism 29 is disposed above the intermediate lever 27. The pile motion mechanism 29 has therein a drive unit (not shown) including a ball screw mechanism or a cam mechanism that is driven by its own drive motor or a loom drive motor M1. When the pile motion mechanism 29 is operated, a drive lever 31 that is fixed on a drive shaft 30 is reciprocally pivoted.
The loom drive motor M1 is controlled by the loom controller C1 connected to a rotary encoder 32 that detects angular position of the loom. The loom controller C1 and the pile warp let-off controller C3 are connected to a patterning controller 33. Data of pile weave patterns is set in the patterning controller 33. The patterning controller 33 transmits signal of a pile weave pattern to the loom controller C1 and the pile warp let-off controller C3 at each predetermined angular position of the loom in one picking cycle. Therefore, the loom controller C1 operates the pile motion mechanism 29 in accordance with the pile weave pattern transmitted by the patterning controller 33.
The drive lever 31 of the pile motion mechanism 29 transmits the reciprocal pivotal movement to the intermediate lever 27 through a rod 35 connected to one arm 34 of the intermediate lever 27. The intermediate lever 27 transmits the rocking motion (or terry motion) to the tension roller 3 and the terry motion roller 20 through the rod 15 connected to the other arm 36 of the intermediate lever 27. The expansion bar 6 which guides the woven cloth W at the front of the loom is supported by the upper end of a rocking lever 38 which is pivotally supported on a shaft 37. The lower end of the rocking lever 38 is connected to the arm 36 of the intermediate lever 27 through a rod 39.
Thus, the reciprocal pivotal movement of the intermediate lever 27 is transmitted to the rocking lever 38 through the rod 39 thereby to swing the rocking lever 38. The intermediate lever 27 transmits the rocking motion (or terry motion) in the same direction as the tension roller 3 and the terry motion roller 20. The terry motion based on the weave pattern causes the tension roller 3, the terry motion roller 20 and the expansion bar 6 to swing frontward of the loom, or rightward in FIG. 1, during loose picking in the pile weaving operation, thereby moving the cloth fell W1 to the position indicated by phantom line, The terry motion causes the tension roller 3, the terry motion roller 20 and the expansion bar 6 to swing backward, or leftward in FIG. 1, during fast picking in the pile weaving operation, thereby moving the cloth fell W1 to the normal position indicated by solid line.
The heald frames 4A, 4B, 4C, 4D through which pile warp yarns TP are passed are driven by a shedding motion device 40. The shedding motion device 40 includes a plurality of shedding motors M4, M5, M6, M7 that are connected to the heald frames 4A, 4B, 4C, 4D, respectively and serve as a heald frame drive system. The speeds of the shedding motors M4, M5, M6, M7 are independently controllable and, therefore, the heald frames 4A, 4B, 4C, 4D can perform shedding operation independently. Although the present embodiment employs four heald frames, six or more heald frames may be used.
The shedding motion device 40 is electrically connected to a shedding motion controller C4 that is in turn electrically connected to the loom controller C1 for mutual communication. The shedding motion controller C4 has therein data of shedding patterns for the ground warp yarns TG and the pile warp yarns TP based on weave patterns set in the patterning controller 33. The shedding motion controller C4 generates drive signals to the shedding motors M4, M5, M6, M7 in accordance with the shedding patterns.
The following will describe the shedding pattern of the pile warp yarns TP set in the shedding motion controller C4 with referring to FIG. 2. The following description will focus on weaving a three-pick pile fabric, or weaving by two times of loose picking followed by one time of fast picking. According to the present invention, however, three or more times of loose picking may be followed by a fast picking.
FIG. 2 shows a shed opening diagram of shed opening of the pile warp yarns TP in which loose picking 1 and loose picking 2 are followed by fast picking. Referring to the diagram in FIG. 2, the pile warn yarns TP are fully opened at the maximum shed opening position between the fast picking and the loose picking 1 and the weft insertion is continuously performed twice. For the loose picking 2 immediately before the fast picking, the pile warn yarns TP are opened for one time of weft insertion. The shed opening curve of the loose picking 2 has a dwell angle α at the maximum shed opening position on the upper and lower sides, respectively. The shed opening curve of the fast picking has a dwell angle β at the maximum shed opening position on the upper and lower sides, respectively.
The dwell angle α corresponds to an angular position, or a rotational angle as measured from the position corresponding to the timing R2 when the pile warp yarns TP reach the maximum shed opening position in the loose picking 2 to the position Q that corresponds to the cross timing K plus 180 degrees. The dwell angle β corresponds to an angular position, or a rotational angle as measured from the position corresponding to the timing R1 when the pile warp yarns TP reach the maximum shed opening position in the fast picking to the position Q that corresponds to the cross timing K plus 180 degrees.
In the present embodiment, the timing R1 when the pile warp yarns TP reach the maximum shed opening position in the fast picking is set to occur earlier than the timing R2 when the pile warp yarns TP reach the maximum shed opening position in the loose picking 2. Therefore, it is so controlled that the rotational speeds of the shedding motors M4, M5, M6, M7 during the period from the time when the pile warp yarns TP are closed after the loose picking 2 is completed until the time when the pile warp yarns TP are opened after the loose picking 2 is completed are faster than those of the shedding motors M4, M5, M6, M7 during the period from the time when the loose picking 1 is completed until the time when the pile warp yarns TP make the opening and closing. In the controlling according to which the timing R1 when the pile warp yarns TP reach the maximum shed opening positon in the fast picking is set to occur earlier than the timing R2 when the pile warp yarns TP reach the maximum shed opening position in the loose picking 2, the period L1 from the cross timing K in the fast picking to the timing R1 is shorter than the period L2 from the cross timing K in the loose picking 2 to the timing R2.
The timing R2 in the loose picking 2 and the timing R1 in the fast picking when the pile warp yarns TP reach the maximum shed opening position are made different. Specifically, the timing R1 in the shed opening curve for the fast picking occurs earlier than the timing R2 in the shed opening curve for the loose picking 2. As a result, the shed opening amount H1 of the pile warp yarns TP at a start of weft insertion for the fast picking (for example, at the rotational angel of 20 degrees) can be set larger than the shed opening amount H2 of the pile warp yarns TP at a start of weft insertion for the loose picking 2. The shed opening amounts H1 and H2 represent the shed opening height between the upper and lower pile warp yarns TP. The larger the shed opening amounts H1 and H2 become, the more strongly the pile warp yarns TP are tensioned vertically and hence the easier the separation of the pile warp yarns TP becomes.
The following will describe the operation of the loose picking and the fast picking in the above-described pile fabric loom with reference of FIGS. 3A, 3B, and 3C. Referring to FIG. 3A, the heald frames 4A, 4B, 4C, 4D (not shown in the drawing) are driven by the shedding motors M4, M5, M6, M7 based on the shed opening curve for the loose picking 1 shown in FIG. 2 and perform shed opening operation of the pile warp yarns TP. The cloth fell W1 is moved forward from its normal position with the woven cloth W by terry motion, as indicated by arrow F. First weft yarn Y1 is inserted through a shed of the pile warp yarns TP based on the shed opening curve for the loose picking 1 and beaten. Because of the forward movement of the cloth fell W1, the pile warp yarns TP are tensioned increasingly. As a result, the separation of the pile warp yarns TP is improved. First weft yarn Y1, second weft yarn Y2, and third weft yarn Y3 have been woven in the cloth W and piles P are formed .
In FIG. 3B, the cloth fell W1 remains at the same position moved away from its normal position as in FIG. 3A. The heald frames 4A, 4B, 4C, 4D are driven by the shedding motors M4, M5, M6, M7 based on the shed opening curve for the loose picking 2 shown in FIG. 2 and perform shed opening operation for the pile warp yarns TP. A second weft yarn Y2 is inserted through a shed of the pile warp yarns TP based on the shed opening curve for the loose picking 2 and beaten. Because the cloth fell W1 remains at the position and the pile warp yarns TP are tensioned , good separation of the pile warp yarns TP remains.
FIG. 3C shows a state in which a third weft yarn Y3 is inserted through a shed for the fast picking as indicated by phantom line in the drawing, and beaten as indicated by solid line in the same drawing. In the fast picking, the cloth fell W1 is moved with the woven cloth W backward in the arrow direction R to the normal position by the terry motion and located at the normal position.
If the heald frames 4A, 4B, 4C, 4D are operated for shedding in the fast picking according to the shed opening curve for the loose picking 2 shown in FIG. 2, the cloth fell W1 is moved backward and then the tension of the pile warp yarns TP is decreased. In the pile fabric loom having the tensioning member 19, the path for adjusting the tension of the pile warp yarns TP is long and subjected to a large resistance, so that the pile warp yarns TP cannot be tensioned quickly and the pile warp yarns TP are loosened significantly. Such decrease of the tension causes the pile warp yarns TP to droop as indicated by phantom line in FIG. 3C thereby to decrease the shed opening. Insufficient shed opening may cause mispick of the third weft yarn Y3.
In the present embodiment, as shown in FIG. 2, the timing R2 in the loose picking 2 and the timing R1 in the fast picking when the pile warp yarns TP reach the maximum shed opening position are different with regard to the respective cross timing K, and the shedding operation of the heald frames 4A, 4B, 4C, 4D for the fast picking is performed based on the shed opening curve in which the timing R1 occurs earlier than the timing R2. As a result, the shed opening amount H1 of the pile warp yarns TP at a start of the weft insertion for the fast picking can be set larger than the shed opening amount H2 of the pile warp yarns TP at a start of the weft insertion for the loose picking 2, so that shown in FIG. 3C, the pile warp yarns TP can be opened without being loosed. The third weft yarn Y3 is inserted into a normal shed of pile warp yarns TP and beaten to form new piles P1.
In the first embodiment, loosening of the pile warp yarns TP due to the movement of the cloth fell W1 in the fast picking is absorbed by increasing the shed opening amount of the pile warp yarns TP from H2 to H1, so that the decrease of the tension of the pile warp yarns TP in the fast picking can be prevented and weft insertion can be stabilized. Because increasing of the shed opening amount of pile warp yarns TP is accomplished directly tensioning the pile warp yarns TP adjacent to the cloth fell W1, the tension control against loosening of pile warp yarns TP can be performed rapidly, which helps to operate the pile fabric loom at an increased speed.
According to the present embodiment, loosening of the pile warp yarns TP may be prevented successfully with a simplified controlling merely by making a shed opening curve in which the timing R1 in the fast picking when the pile warp yarns TP reach the maximum shed opening position is set to occur earlier than the timing R2 in the loose picking 2 when the pile warp yarns TP reach the maximum shed opening position. Therefore, the configuration to control the pile warp yarns TP can be simplified. In the configuration in which the heald frames 4A, 4B, 4C, 4D are driven by the respective independent shedding motors M4, M5, M6, M7, the heald frames 4A, 4B, 4C, 4D are driven freely and accurately based on a predetermined shed opening curve. As a result, tension loosening of the pile warp yarns TP can be suppressed securely.
In case of occurrence of mispick of weft yarn in a pile fabric loom, the first, the second, and the third weft yarns Y1, Y2, Y3 that are inserted for the loose picking and the fast picking need to be removed from the woven cloth W. Remedy against the mispick involves troublesome repairing work, cost for mispicked weft yarn, and formation of unwanted weaving bar in the woven fabric. In the present embodiment, occurrence of mispick caused by poor shed opening of pile weft yarns can be prevented, which helps to reduce troublesome repairing operation, waste of weft yarns, formation of weaving bar, and irregularity of density in woven fabric.
Tension of the pile warp yarns TP tends to be increased by forward movement of the cloth fell W1 and decreased by backward movement of the cloth fell W1. According to the present embodiment in which the tension of the pile warp yarns TP is increased only in the fast picking and the tension of the pile warp yarns TP in the loose picking is set suitable for forming piles, there is no fear of an increase of the tension of the pile warp yarns in the loose picking that eliminates piles woven by the fast picking, so that piles with uneven height may be prevented. In the first embodiment according to which the timing R2 in the loose picking 2 when the pile warp yarns TP reach the maximum shed opening position occurs later than the timing R1 in the fast picking when the pile warp yarns TP reach the maximum shed opening position, the increase of the tension of the pile warp yarns TP that eliminates the piles can be prevented. Unlike the second embodiment which is be described later herein, the cross timing K in the loose picking 2 and the fast picking can be the same. Therefore, there is no fear that the weave of the fabric is influenced by variation of beating force in the loose picking 2 and the fast picking.

Second embodiment

The following will describe a second embodiment according to the present invention with reference to FIG. 4. The second embodiment differs from the first embodiment in that the shed opening curve in the loose picking and the shed opening curve in the fast picking are made different. The same reference numerals will be used to denote those components or elements which correspond to the counterparts of the first embodiment and the description thereof will not be reiterated.
FIG. 4 shows a shed opening curve for weaving a three-pick pile fabric, or weaving by the loose picking 1, and the loose picking 2 followed by the fast picking. The timings R1 of the loose picking 2 and the fast picking, at which the maximum shed opening positions are reached, are set the same.
The cross timing K2 in the fast picking is set earlier than the cross timing K1 in the loose picking 2. Thus, the shedding motors M4, M5, M6, M7 driving the heald frames 4A, 4B, 4C, 4D are controlled so that the rotational speeds thereof during the shed closing period of the pile warp yarns TP, or the period from the time of the maximum shed opening in the loose picking 2 to the cross timing K2 in the fast picking are increased. Furthermore, the shedding motors M4, M5, M6, M7 are controlled so that the rotational speeds thereof during the shed opening period or the period from the cross timing K2 in the fast picking to the timing R in the fast picking at which the maximum shed opening position is reached, are decreased.
Since the cross timing K2 in the fast picking is set earlier than the cross timing K1 in the loose picking 2, the shed opening curve in the fast picking is different from that in the shed opening curve in the loose picking 2. Therefore, the shed opening amount H3 of the pile warp yarns TP at a start of the weft insertion for the fast picking is made larger than the shed opening amount H4 of the pile warp yarns TP at a start of the weft insertion for the loose picking 2. The method of the second embodiment in which the shed opening curve for the fast picking is made different from that for the loose picking 2 by changing the cross timing K2 is simplified and has the same effects as the method of the first embodiment. In the second embodiment in which the timing R in the loose picking 2, at which the maximum shed opening position is reached, may be set the same as that in the fast picking, the shed opening speed during the period from the cross timing K2 in the fast picking to the timing R is not increased as compared to the configuration in the first embodiment and, therefore, the tension of the pile warp yarns TP is not increased rapidly.

Third embodiment

The following will describe a third embodiment according to the present invention with reference to FIG. 5. The same reference numerals will be used to denote those components or elements which correspond to the counterparts of the first embodiment and the description thereof will not be reiterated. The third embodiment differs from the first embodiment in that the shed opening curve in the loose pickings 1, 2 and the fast picking are set as a quadratic curve such as sine curve so that no standstill exists at a position around the maximum shed opening on the upper and lower sides.
In the shed opening curve of FIG. 5 having no standstill, a region that corresponds to a predetermined ratio ΔS (for example, three percent) of the stroke S of the maximum shed opening position on the upper and lower sides has very small amplitude and, therefore, is approximated as a standstill. In the loose picking 2, the rotational speeds of the shedding motors M4, M5, M6, M7 are controlled so that the period of the angular position in the region at the predetermined rate ΔS becomes the same as the dwell angle α of FIG. 2. In the fast picking, the rotational speeds of the shedding motors M4, M5, M6, M7 are controlled so that the period of the angular position in the region at the predetermined rate ΔS becomes the same as the dwell angle β of FIG. 2. In the present embodiment, the period of the angular position in the region at the predetermined rate ΔS is regarded as a dwell angle and described as the dwell angle α or the dwell angle β.
In the third embodiment, the shed opening curve having no standstill has the dwell angles α, β that are approximate to each other, so that the shed opening amount H5 at a start of the weft insertion for the fast picking can be larger than the shed opening amount H6 at a start of the weft insertion for the loose picking 2 and decrease of the tension by loosening of the pile warp yarns TP is prevented.
The present invention is not limited to the embodiments described above, but it may be modified into various alternative embodiments as exemplified below.

(1) A dobby machine having electromagnetic devices such as solenoids may be used to drive the respective heald frames 4A, 4B, 4C, 4D.
(2) In the shed opening curve of the loose picking 2 and the fast picking shown in FIG. 6, the timing of the loose picking 2 and the timing of the fast picking (the cross timing K to close the shed of the pile warp yarns TP and the timing R when the pile warp yarns TP reach a maximum shed opening position) may be set the same with each other. The curve A1 in the fast picking may be changed from the curve A2 in the loose picking 2. As compared to the curve A2 during the period L from the cross timing K to close the shed of the pile warp yarns TP to the timing R when the pile warp yarns TP reach the maximum shed opening position in the loose picking 2, the curve A1 during the similar period L from the cross timing K to close the shed of the pile warp yarns TP to the timing R when the pile warp yarns TP reach the maximum shed opening position in the fast picking shows a rapid speed change to increase the shed opening amount H5. Such rapid change of speed as shown by the curve A1 for the fast picking increases the shed opening amount H5 for the fast picking larger than the shed opening amount H6 for the loose picking 2. As a result, the shed opening amount H5 at a start of weft insertion for the fast picking can be increased. In this embodiment, since the cross timings K to close the shed of the pile warp yarns TP and the timings R when the pile warp yarns TP reach the maximum shed opening position in the fast picking and the loose picking 2 can be the same with each other, decrease of tension by loosening of the pile warp yarns TP can be suppressed by a similar weave condition to the prior art.

There is provided a method for controlling shed opening of pile warp yarns in a pile fabric loom. The pile fabric loom includes a plurality of heald frames through which the pile warp yarns are passed, and a plurality of drive devices driving the respective heald frames and forms piles by forward and rearward movement of cloth fell. The method is characterized by setting a shed opening amount of the pile warp yarns at a start of weft insertion in fast picking larger than a shed opening amount of the pile warp yarns at a start of weft insertion in loose picking.

Claims

A method for controlling shed opening of pile warp yarns (TP) in a pile fabric loom, wherein the pile fabric loom includes a plurality of heald frames (4A, 4B, 4C, 4D) through which the pile warp yarns (TP) are passed, and a plurality of drive devices driving the respective heald frames (4A, 4B, 4C, 4D) and forms piles (P, P1) by forward and rearward movement of cloth fell (W1),
characterized by
setting a shed opening amount (H1, H3, H5) of the pile warp yarns (TP) at a start of weft insertion in fast picking larger than a shed opening amount (H2, H4, H6) of the pile warp yarns (TP) at a start of weft insertion in loose picking.
The method for controlling the shed opening of the pile warp yarns (TP) in the pile fabric loom according to claim 1, characterized by setting timing (R1) when the pile warp yarns (TP) reach a maximum shed opening position in the fast picking earlier than timing (R2) when the pile warp yarns (TP) reach a maximum shed opening position in the loose picking.
The method for controlling the shed opening of the pile warp yarns (TP) in the pile fabric loom according to claim 1, characterized by:
setting timing (R) when the pile warp yarns (TP) reach a maximum shed opening position in the fast picking the same as timing (R) when the pile warp yarns (TP) reach a maximum shed opening position in the loose picking, and

setting cross timing (K2) to close a shed of the pile warp yarns (TP) in the fast picking earlier than cross timing (K1) to close a shed of the pile warp yarns (TP) in the loose picking.
The method for controlling the shed opening of the pile warp yarns (TP) in the pile fabric loom according to any one of claims 1 through 3, characterized in that the plural drive devices include respective shedding motors (M4, M5, M6, M7), wherein each heald frame (4A, 4B, 4C, 4D) is connected to and driven by the corresponding shedding motor (M4, M5, M6, M7).
The method for controlling the shed opening of the pile warp yarns (TP) in the pile fabric loom according to claim 1, characterized by:
setting timing (R) when the pile warp yarns (TP) reach a maximum shed opening position in the fast picking the same as timing (R) when the pile warp yarns (TP) reach a maximum shed opening position in the loose picking;

setting cross timing (K) to close a shed of the pile warp yarns (TP) in the fast picking the same as cross timing (K) to close a shed of the pile warp yarns (TP) in the loose picking; and

changing a shed opening curve (A1) of the pile warp yarns (TP) during a period (L) from the cross timing (K) to close the shed of the pile warp yarns (TP) to the timing (R) when the pile warp yarns (TP) reach the maximum shed opening position in the fast picking from a shed opening curve (A2) of the pile warp yarns (TP) during a period (L) from the cross timing (K) to close the shed of the pile warp yarns (TP) to the timing (R) when the pile warp yarns (TP) reach the maximum shed opening position in the loosing picking so that the shed opening amount (H5) of the pile warp yarns (TP) in the fast picking is larger than the shed opening amount (H6) of the pile warp yarns (TP) in the loose picking.