EP1630272A2

EP1630272A2 - Weft brake device and method for controlling a weft brake device

Info

Publication number: EP1630272A2
Application number: EP05017592A
Authority: EP
Inventors: Koki Yamazaki; Kazuaki Nozaki; Hideyuki Kontani; Hirohisa Kitamura
Original assignee: Tsudakoma Industrial Co Ltd
Current assignee: Tsudakoma Corp
Priority date: 2004-08-30
Filing date: 2005-08-12
Publication date: 2006-03-01
Anticipated expiration: 2025-08-12
Also published as: KR20060049244A; EP1630272A3; DE602005024648D1; JP2006063498A; EP1630272B1

Abstract

A fluid jet loom (1) performs a weft insertion process in which a retaining pin (8) retracts to release a weft yarn (4) stored in a weft measuring-and-storing device (5), a weft brake device (40) applies a braking force to the weft yarn (4) at a brake start timing (t3, θ3) while the released weft yarn (4) is being inserted into a shed (17) by a jet from a main nozzle (10), and the retaining pin (8) projects to stop the weft yarn (4) and thereby finishes the weft insertion process. A remaining weft-insertion length (L1) to a final weft arrival position is input beforehand to the weft brake device (40) as an input value, and the weft brake device (40) determines the brake start timing (t3, θ3) on the basis of the remaining weft-insertion length (L1) and applies the braking force to the weft yarn (4) at the determined brake start timing (t3, θ3).

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a weft brake device for applying a braking force to a weft yarn at a final stage of weft insertion in a fluid jet loom, and also relates to a method for controlling the weft brake device.

2. Description of the Related Art

Japanese Unexamined Patent Application Publication No. 56-93659 discloses a weft-breakage prevention device for use in a weft measuring-and-storing device of a weft-winding type including a retractable retaining pin. In this weft-breakage prevention device, a brake shoe is disposed near a yarn-winding surface. The brake shoe comes into contact with the yarn-winding surface in synchronization with the rotation of a main shaft of a loom. Thus, a brake is applied to a weft yarn that is being pulled out from the yarn-winding surface, and the weft feed velocity, i.e., the weft-insertion velocity, is reduced accordingly.
In the above-described weft-breakage prevention device, a period in which the brake is applied to the weft yarn is started a short time before the weft yarn release is stopped by the retaining pin. Accordingly, a sudden increase of weft tension caused by the stoppage of the weft yarn is suppressed, and the breakage of the weft yarn is prevented.
In addition, Japanese Patent No. 3278874 discloses a jet loom including a weft brake device. This loom includes a weft measuring-and-storing device of a weft-winding type having a weft-retaining pin and the weft brake device disposed between the weft measuring-and-storing device and a main nozzle. The weft brake device bends a weft yarn by rotating a brake wire, and thereby applies a braking force to the weft yarn in a predetermined time period at the final stage of weft insertion.
In the technique of Japanese Patent No. 3278874, the weft yarn is pulled out from the weft measuring-and-storing device by a jet from the main nozzle, and the amount by which the weft yarn is pulled out is determined on the basis of a ballooning number, i.e., the number of times the weft yarn is detected while it is being released from the weft measuring-and-storing device. When a predetermined time elapses after an amount of weft yarn corresponding to a predetermined ballooning number is released, the braking force is applied to the weft yarn by bending the weft yarn with the brake wire. The predetermined ballooning number is set to a number less than a total ballooning number corresponding to the total amount of weft yarn required for weft insertion.
According to the technique of Japanese Patent No. 3278874, a brake start time of the weft brake device must be adjusted depending on the type and state of the weft yarn, the weaving width, etc. However, it is not easy for an operator who is not experienced to recognize the setting in terms of time, and it takes a relatively long time to adjust the brake start time. In addition, since the extent of actual adjustment corresponding to an input value cannot be realized, the input value may be too high or low relative to a value corresponding to a desired state. Therefore, a process of inputting a value and confirming the state of the loom must be repeated a plurality of times, and accordingly a long adjustment time is required. For this reason, this weft brake device is not convenient to use.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a weft brake device for a fluid jet loom which applies a braking force to a weft yarn after the middle stage of weft insertion and in which a brake start time can be easily set even by an operator who is not experienced.
In order to achieve the above-described object, according to the present invention, a fluid jet loom includes a weft brake device and a weft measuring-and-storing device of a weft-winding type having a retractable retaining pin, the weft brake device being disposed between the weft measuring-and-storing device and a main nozzle for weft insertion and applying a braking force to a weft yarn pulled out from the weft measuring-and-storing device. In a weft insertion process, the retaining pin retracts to release the weft yarn stored in the weft measuring-and-storing device in a wound state, the weft brake device applies the braking force to the weft yarn at a brake start timing while the released weft yarn is being inserted into a shed between warp yarns by a jet from the main nozzle, and the retaining pin projects to stop the weft yarn and thereby finishes the weft insertion process. A remaining weft-insertion length to a final weft arrival position at the time when braking starts is input beforehand to the weft brake device as an input value, and the weft brake device determines the brake start timing on the basis of the input remaining weft-insertion length and applies the braking force to the weft yarn at the determined brake start timing while the fluid jet loom is in operation.
As described above, the remaining weft-insertion length to the final weft arrival position at the time when braking starts is input beforehand as the input value for determining the brake start timing for applying the weft brake, and the brake start timing is determined on the basis of the input remaining weft-insertion length. The "final weft arrival position" refers to a certain position within a specific range. The specific range is a range between the selvedge position at the downstream side in the weft-insertion direction and a final weft arrival end position. Preferably, the final weft arrival position is set to a selvedge position at a downstream side in a weft-insertion direction or a final weft arrival end position. However, the final weft arrival position may also be set to an arbitrary position in this range, for example, a catch-cord position, a filler-head position, or a position of a selvage cutter.
The "remaining weft-insertion length" refers to either (1) distance between the front end position of the weft yarn and the final weft arrival position at the time when braking starts; or (2) remaining release length in the weft measuring-and-storing device at the time when braking starts. The length or distance defined above is input in terms of an actual length value. Alternatively, values reflecting the length, for example, a percentage of the length when a single pick length is 100 may also be input. When the actual length value is input, the weft length for a single pick is necessary. Accordingly, the weft length for a single pick is also input.
In the weft brake device which applies the braking force to the weft yarn, the brake may be applied using a known method, for example, by bending the weft yarn, changing the contact pressure applied to the weft yarn, applying a braking force by an airflow, etc. In the weft brake device, the operation of activating the weft brake may be started in synchronization with a release signal input instead of using the determined brake start timing.
The brake start timing for the weft brake device is determined by one of methods (1) and (2) described below: (1) The brake start timing is determined by calculation based on a formula including an insertion velocity of the weft yarn in a weft insertion period, a value relating to a weft insertion length for each pick, and the remaining weft-insertion length. For example, the weft insertion velocity is determined from the relationship between the weft-insertion timing and the goal arrival timing. Alternatively, the weft insertion velocity is determined from the generation cycle of a weft release signal. To be accurate, the value relating to the weft insertion length for each pick is equal to the release length for each pick in the weft measuring-and-storing device. However, an equivalent value which is less accurate but is more familiar to the operator and more convenient (e.g., a reed width) is used in practice. The weft release signal may be substituted by other detection signals, for example, signals from weft sensors or the like provided in the warp shed. (2) A database including the brake start timing with respect to control conditions of the loom and the remaining weft-insertion length is prepared in advance, and the brake start timing corresponding to the remaining weft-insertion length may be determined by searching the database.
The present invention provides the following advantages. That is, since the remaining weft-insertion length is used as an input value for changing the brake start timing of the weft brake device, the operator can easily recognize the input value and adjust the brake start timing. In addition, the brake start timing of the weft brake is automatically determined by calculation when the remaining weft-insertion length is input. Therefore, the operator can quickly set a desired brake state for the weft yarn. The remaining weft-insertion length used for changing the brake start timing of the weft brake device directly corresponds to the brake period for the weft yarn. Therefore, when, for example, only the weaving width (reed width) is changed, the previous settings can be used without change unless it is necessary to change the brake period. Accordingly, the frequency of changing the setting is reduced compared to that in the known structure. If the brake start timing of the weft brake device is set in terms of time as in the known structure, the brake start time must be set again in accordance with the change in the reed width to obtain a desired brake period. Such a process can be omitted in the structure according to the present invention, and the task required when the reed width is changed is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a system diagram showing a fluid jet loom, a weft brake device, and a brake control unit according to the present invention;
Figs. 2A and 2B are diagrams showing a method for determining a brake start timing in the brake control unit according to the present invention;
Fig. 3 is a block diagram showing the main part of a brake control unit according to a first embodiment of the present invention;
Figs. 4A and 4B are diagrams showing an input unit and a display unit included in the weft brake device according to the present invention;
Fig. 5 is a diagram showing a weft insertion characteristic and signals fed to each component according to the first embodiment of the present invention;
Fig. 6 is a block diagram showing the main part of a brake control unit according to a second embodiment of the present invention;
Fig. 7 is a block diagram showing the main part of a brake control unit according to a third embodiment of the present invention; and
Fig. 8 is a diagram showing the weft insertion characteristics and signals from each part according to the third embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Structures of Fluid Jet Loom 1 and Brake Control Unit 41 of Weft Brake Device 40

Fig. 1 shows an air jet loom as an example of a fluid jet loom 1 according to the present invention. The fluid jet loom 1 performs, for example, two-color weft insertion. Two weft yarns 4 are pulled out from respective feeders 3 supported by respective holders 2, guided to rotating yarn guides 6 included in drum-shaped weft measuring-and-storing devices 5 of a weft-winding type, and are wound around yarn-winding surfaces of drums 7 when the rotating yarn guides 6 rotate while the weft yarns 4 are retained by retaining pins 8 on the yarn-winding surfaces of the drums 7 in the stationary state. Thus, the lengths of the warp yarns 4 are measured, and the warp yarns 4 are stored until weft insertion is performed. The rotating yarn guides 6 are driven by drive motors 34.
In a weft insertion process, the retaining pin 8 corresponding to the weft yarn 4 to be inserted is driven by an operating unit 9 and moves away from the yarn-winding surface of the drum 7. Accordingly, the weft yarn 4 wound around the yarn-winding surface of the drum 7 is released from the drum 7 by an amount necessary for a single weft insertion, and is guided to a main nozzle 10 for weft insertion via guides 36 and a weft brake device 40.
The weft brake device 40 is positioned between the weft measuring-and-storing device 5 and the main nozzle 10. During the weft insertion process, the weft yarn 4 is pulled out from the weft measuring-and-storing device 5 by a jet from the main nozzle 10. The weft brake device 40 includes, for example, a bending-type weft brake 42 and a brake-driving actuator 43 for applying a braking force to the weft yarn 4 being pulled out from the weft measuring-and-storing device 5 at a predetermined brake start timing. The weft brake 42 keeps the weft yarn 4 in a linearly stretched state when no braking force is to be applied to the weft yarns 4. When a braking force is to be applied to the weft yarn 4, the weft brake 42 is rotated by a predetermined angle to bend the weft-insertion path. Accordingly, contact (frictional) resistance between the weft yarn 4 in the bent state and the weft brake 42 is increased, and this resistance functions as the braking force.
In the weft insertion process, the main nozzle 10 corresponding to the weft yarn 4 to be inserted ejects compressed air 15 into a shed 17 between warp yarns 16 in an ejection period (period from an ejection start timing to an ejection end timing). Accordingly, the weft yarn 4 is inserted into the shed 17 along a weft-insertion path in the shed 17 by an amount necessary for a single weft insertion. The compressed air 15 is supplied from a compressed air source 11 via a pressure adjustment valve 14, an air supply pipe 12, and an electromagnetic on-off valve 13 provided in the air supply pipe 12 during the ejection period for weft insertion. The pressure adjustment valve 14 is provided for setting a pressure of the compressed air 15 supplied to the main nozzle 10 to a predetermined value.
While the weft yarn 4 is being inserted, one or more groups of sub nozzles 18 simultaneously eject the compressed air 15 in the weft-insertion direction. Alternatively, the sub nozzles 18 perform relay ejection in accordance with the weft-insertion velocity. Thus, the weft yarn 4 is pushed in the weft-insertion direction in the shed 17. The compressed air 15 is supplied to the sub nozzles 18 from the compressed air source 11 via a pressure adjustment valve 19, air supply pipes 22, and electromagnetic on-off valves 23 provided in the air supply pipes 22. The pressure adjustment valve 19 sets a pressure of the compressed air 15 supplied to the sub nozzles 18 to a predetermined value.
If the weft yarn 4 is normally inserted by the jets from the main nozzle 10 and the sub nozzles 18, the weft yarn 4 is beaten against a cloth fell 21a by a reed 20 and is woven into a cloth 21. Then, the weft yarn 4 is cut by a yarn cutter 25 at the upstream side in the weft-insertion direction. Several catch cords 24 are provided near the selvedge at the downstream side in the weft-insertion direction. After the weft insertion, the weft yarn 4 maintains the stretched state since it is retained by a twisted portion of the catch cords 24. Then, after the weft yarn 4 is woven into the cloth 20, it is cut by a selvage cutter 63. The trimmed selvedge is discarded together with the catch cords 24.
In the weft insertion process, success or failure of the weft insertion is detected by a weft feeler 27. The weft feeler 27 faces the weft-insertion path at a position near the selvedge at the downstream side in the weft-insertion direction, and the weft yarn 4 reaches this position if the weft yarn 4 is normally inserted. The weft feeler 27 detects whether or not the weft yarn 4 has arrived within a predetermined detection (check) period, and thereby determines whether the weft insertion succeeded or failed. The weft feeler 27 outputs a weft arrival signal if the weft insertion is performed normally, and outputs a weft stop signal if the weft insertion fails. The weft arrival signal or the weft stop signal is transmitted to a main controller 32 for each pick. The weft feeler 27 includes a light emitter and a light receiver facing the weft-insertion path (a reed groove of a modified reed). However, the weft feeler 27 may, of course, also be of a reflective or transmissive type.
The release status of the weft yarn 4 is detected by a release sensor 26 at a position near the weft measuring-and-storing device 5. The release sensor 26 includes a light emitter and a light receiver disposed along a release path (balloon-forming path) of the weft yarn 4 so as to face each other in the radial direction of the drum 7. The release sensor 26 detects the passage of the released weft yarn 4 and generates a pulse release signal S7.
The drive motor 34 and the operating unit 9 of the weft measuring-and-storing device 5 is controlled by a length measurement control unit 35 included in a weft-insertion controller 30. The actuator 43 of the weft brake device 40 is controlled by a brake control unit 41 included in the weft-insertion controller 30. The electromagnetic on-off valve 13 corresponding to the main nozzle 10 and the electromagnetic on-off valves 23 corresponding to the sub nozzles 18 are controlled by an ejection control unit 37 included in the weft-insertion controller 30.
The weft-insertion controller 30 controls the insertion of the corresponding components on the basis of a signal representing a rotation angle θ of a main shaft 28 of the fluid jet loom 1 obtained from an angle detector 29 connected to the main shaft 28, an operation signal S1 from the main controller 32, a weft selection signal S8 from a weft-selection signal generator 33, and various input values set by a setter 31 in advance. The weft-insertion controller 30, the setter 31, the main controller 32, and the weft-selection signal generator 33 communicate with one another via a control bus 38. The setter 31 includes a touch-panel input unit 44, a display 45, a central processing unit (CPU) 46, and a memory 47 connected to the CPU 46, which are connected to the control bus 38 via a port 39.
Provided that the operation signal S1 is transmitted from the main controller 32, the length measurement controller 35 controls the on/off state, the rotational speed, and the amount of rotation of the drive motor 34 corresponding to the selected weft yarn 4 on the basis of the signal representing the rotation angle θ of the main shaft 28 and the weft selection signal S8 from the weft-selection signal generator 33. In addition, when the weft insertion starts, the length measurement controller 35 controls the operating unit 9 to retract the retaining pin 8 so that the weft yarn 4 is released. Then, after the weft yarn 4 is released by a necessary number of turns, the length measurement controller 35 controls the operating unit 9 to project the retaining pin 8, so that the weft yarn 4 is stopped from being released.
In addition, provided that the operation signal S1 is transmitted from the main controller 32, the brake control unit 41 receives the signal representing the rotation angle θ of the main shaft 28, the weft selection signal S8 from the weft-selection signal generator 33, and a remaining weft-insertion length L1 to a final weft arrival position input form the setter 31, and controls the on/off state, the rotational speed, and the amount of rotation of the actuator 43 of the weft brake device 40 corresponding to the selected weft yarn 4. The remaining weft-insertion length L1 is set as an input value for determining a brake start time of the weft brake device 40, and is input in advance by the setter 31. Thus, the weft brake device 40 determines the brake start timing of the weft brake 42 on the basis of the remaining weft-insertion length L1, and applies a braking force to the weft yarn 4 at the brake start timing during the operation of the fluid jet loom 1.
In addition, provided that the operation signal S1 is transmitted from the main controller 32, the ejection control unit 37 receives the signal corresponding to the rotation angle θ of the main shaft 28, the weft selection signal S8 from the weft-selection signal generator 33, and the ejection period (period from the ejection start timing to the ejection end timing) from the setter 31, and activates the electromagnetic on-off valve 13 corresponding to the selected weft yarn 4 and the electromagnetic on-off valves 23 in ejection periods in accordance with the rotation angle θ of the main shaft 28. Accordingly, the ejection control unit 37 performs simultaneous injection or relay injection of the compressed air 15.
As described above, when the weft insertion is performed in the fluid jet loom 1, the retaining pin 8 is retracted so that the weft yarn 4 wound around the yarn-winding surface of the weft measuring-and-storing device 5 is released, and the released weft yarn 4 is inserted into the shed 17 between the warp yarns 16 by the jet from the weft-insertion main nozzle 10. In this process, the weft brake 42 of the weft brake device 40 applies the braking force to the weft yarn 4 at the determined brake start timing, and the retaining pin 8 projects to stop the weft yarn 4. Accordingly, the weft insertion is finished.
The remaining weft-insertion length L1 to the final weft arrival position at the time when braking starts, which serves as an input value for determining the brake start time of the weft brake 42, is input to the brake control unit 41 of the weft brake device 40 by the setter 31 in advance. The brake control unit 41 determines the brake start timing of the weft brake 42 on the basis of the remaining weft-insertion length L1 input thereto. In addition, during the operation of the fluid jet loom 1, the brake control unit 41 applies the braking force to the weft yarn 4 at the determined brake start timing.
In the above expression "remaining weft-insertion length L1 to the final weft arrival position at the time when braking starts", the "final weft arrival position" refers to a certain position within a specific range. The specific range is a range between the selvedge position at the downstream side in the weft-insertion direction and a final weft arrival end position. Preferably, as shown in Fig. 1, the final weft arrival position is set to the selvedge position p1 at the downstream side in the weft-insertion direction or the final weft arrival end position p2. However, the final weft arrival position may also be set to an arbitrary position in this range, for example, a catch-cord position p3, a filler-head position p4, or a position p5 of the selvage cutter 63. In the example shown in Fig. 1, the final weft arrival position is set to the selvedge position p1 at the downstream side in the weft-insertion direction.
In addition, in the expression "remaining weft-insertion length L1 to the final weft arrival position at the time when braking starts", the "remaining weft-insertion length L1" refers to either (1) length or distance between the front end position of the weft yarn 4 and the final weft arrival position at the time when braking starts; or (2) remaining release length in the weft measuring-and-storing device 5 at the time when braking starts. In Fig. 1, the final weft arrival position is set to the selvedge position p1 at the downstream side in the weft-insertion direction. Accordingly, the "remaining weft-insertion length L1" is set to the distance between the front end position of the weft yarn 4 at the time when braking starts and the final weft arrival position, i.e., the selvedge position p1 at the downstream side in the weft-insertion direction. Therefore, the "weft-insertion length L2" is the length between the selvedge position at the upstream side in the weft-insertion direction and the front end position of the weft yarn 4. The sum of the "remaining weft-insertion length L1" and the "weft-insertion length L2" is equivalent to a value (reed width) L0 corresponding to a weft insertion length for each pick.
The length or distance defined above as (1) and (2) is input by the setter 31 in terms of an actual length value. Alternatively, other values reflecting the length, for example, a percentage of the length when a single pick length is 100 may also be input by the setter 31. When the actual length value is input, the weft length for a single pick is necessary. Accordingly, the weft length for a single pick is also input by the setter 31.
The weft brake device 40 is controlled at the determined set angle (on/off timing) in terms of the rotation angle θ of the main shaft 28 in the fluid jet loom 1 which performs two-color weft insertion. The brake control unit 41 determines the brake start timing t3 or the brake start timing θ3 by calculation based on an equation including the insertion velocity of the weft yarn 4 in the weft insertion period, the reed width L0 which relates to the weft length for a single pick, and the remaining weft-insertion length L1.
The brake start timing t3 represents the brake start timing in terms of time t, and the brake start timing θ3 represents the brake start timing in terms of the rotation angle θ of the main shaft 28. In the following descriptions, timings in terms of time t are indicated by adding the letter 't', and timings in terms of the rotation angle θ of the main shaft 28 are indicated by adding the letter 'θ'.

Method for Obtaining Brake Start Timing t3 or θ3

Figs. 2A and 2B show the principal of operation according to the present invention, more specifically, a method for obtaining the brake start timing t3 or θ3. Fig. 2A shows the relationship among a weft-insertion start timing θ1 (60°), a goal arrival timing θ2 (230°), the reed width L0 (210 cm), the remaining weft-insertion length L1, and the weft-insertion length L2. Fig. 2B is a graph in which the horizontal axis x shows the time t or the rotation angle θ and the vertical axis y shows the insertion length (distance) L of the weft yarn 4.
1) A case is considered in which the weft insertion is started at the weft-insertion start timing θ1 (60°), and the front end of the weft yarn 4 reaches the position corresponding to the reed width L0 (210 cm) at the goal arrival timing θ2 (230°), as shown in Figs. 2A and 2B.
2) When it is assumed that the front end of the weft yarn 4 is inserted at a constant insertion velocity during the weft insertion, the insertion characteristic of the front end of the weft yarn 4 can be expressed by a linear line, more specifically, by a linear function y = ax + b. The coefficient (inclination of the linear line) a represents the insertion velocity of the weft yarn 4 in the shed 17 during the weft insertion. In this linear function, the two coefficients a and b can be determined using an equation of a line that passes through two points (x1, y1) and (x2, y2). This equation is expressed as y = [(y2 - y1) / (x2 - xl)] x (x - x1) + y1.
3) When it is assumed that the rotational speed of the loom is maintained at N = 600 rpm, the goal arrival timing t2 is calculated on the basis of the weft-insertion start timing θ1 and the weft-insertion start timing t1 = 0 ms as t2 = (0.1 ms/360°) × (230° - 60°) = 47.2 ms. Accordingly, by substituting (x1, y1) = (0, 0) and (x2, y2) = (47.2, 210), the linear function is determined as y = 4.449x. Thus, the coefficients a and b are determined as 4.449 and 0, respectively.
4) In order to determine the brake start timing t3 after correction, the linear function y = ax + b is converted to x = (y - b)/a. The weft-insertion length L2 to be substituted for y is obtained as L2 = L0 - L1, and accordingly the brake start timing t3 after correction is calculated as t3 = [(L0 - L1) - b]/a.
5) When the coefficients a and b are substituted into the equation of brake start timing t3 = [(L0 - L1) - b]/a, t3 is obtained as t3 = (L0 - L1)/4.449. Accordingly, when the rotational speed N of the loom is N = 600 rpm, the weft-insertion start timing is θ1 (60°), the goal arrival timing is θ2 (230°), and the reed width is L0 (210 cm), the brake start timing t3 (ms) for the remaining weft-insertion length L1 (cm) is calculated using the weft-insertion start timing θ1 (60°) as the origin (t3 = 0) as below. The weft-insertion length L2 (cm) is also shown as a reference.

L1 (cm) L2 (cm) t3 (ms)

40 170 38.2

30 180 40.5

20 190 42.7

10 200 45.0

0 210 47.2

6) Instead of the calculations in terms of time t, the brake start timing θ3 (°) based on the rotation angle θ of the main shaft 28 may also be determined. When the rotational speed N of the loom is N = 600 rpm, the weft-insertion start timing is θ1 (60°), the goal arrival timing is θ2 (230°), and the reed width is L0 (210 cm), the brake start timing θ3 is obtained from a conversion equation θ3 = (x × 3600°/1s) + 60° as below. The weft-insertion length L2 (cm) is also shown as a reference.

L1 (cm) L2 (cm) θ3(°)

40 170 197.5

30 180 205.8

20 190 213.7

10 200 222.0

0 210 230.0
As shown in Figs. 5 and 8, the actual insertion characteristic of the weft yarn 4 is expressed by a curve close to a quadric curve, and the initial velocity is gradually reduced. Therefore, the brake start timing t3 or θ3 is corrected as necessary by taking the curve (more specifically, a function of second or higher order) into account or by referring to experimental data showing the actual insertion characteristic. Thus, the brake start timing corresponding to the actual insertion characteristic in which the initial velocity is reduced can be obtained.
As described above, the brake control unit 41 of the weft brake device 40 determines the brake start timing t3 (ms) or θ3 (°) using the above equations on the basis of the remaining weft-insertion length L1. In addition, during the operation of the fluid jet loom 1, the brake control unit 41 activates the weft brake 42 of the weft brake device 40 and applies the braking force to the weft yarn 4 at the determined brake start timing t3 (ms) or θ3 (°), so that the weft yarn 4 being inserted is decelerated. The braking force is cleared at a suitable timing after the weft insertion. Thus, the weft yarn 4 receives the braking force when the remaining weft-insertion length becomes L1. Accordingly, even when the retaining pin 8 suddenly retains the weft yarn 4 on the yarn-winding surface of the drum 7 after the brake start timing t3 or θ3, sudden increase of the tension applied to the weft yarn 4 can be suppressed. Accordingly, the breakage of the weft yarn 4 at this time can be reliably prevented.

Embodiments

First Embodiment (Figs. 3, 4, and 5)

Fig. 3 shows a brake control unit 41 according to a first embodiment. In order to control the operation of a weft brake device 40, the brake control unit 41 includes a signal converter 48, a timing signal generator 49, a delay time calculator 51 included in a brake-start-timing determiner 50, a brake-start-timing signal generator 52 included in the brake-start-timing determiner 50, a pulse generator 53 included in the brake-start-timing determiner 50, a pulse generator 54, a gate signal generator 55, a flip-flop 56, a drive circuit 57, and an amplifier circuit 58. These components activate the weft brake 42 of the weft brake device 40 by controlling an actuator 43, such as a stepping motor, in the brake period.
Figs. 4A and 4B show examples of the touch-panel input unit 44 and the display 45, respectively, included in the setter 31. Fig. 4A shows a display screen used to input values, and Fig. 4B shows a screen displayed when the setting of the values is finished. The remaining weft-insertion length L1 corresponds to the position at which the weft brake 42 is activated, and it is therefore shown as "brake position" on the screen.
When values are input using the touch-panel input unit 44 and the display 45, an operator operates the input unit 44 of the setter 31 and displays the screen shown in Fig. 4A on the display 45. The operator touches ten keys/function keys 59 on the screen to set, for example, the reed width L0, which relates to the weft insertion length for each pick, to 210 cm, the remaining weft-insertion length (brake position) L1 to 105 cm, the amount of operation of the weft brake 42 of the weft brake device 40 (rotational stroke) SL to 11 mm, the diameter D of the drum 7 to 700 mm, the brake-control ON timing θ4 to 60°, the brake-control OFF timing θ5 to 250°, the weft-insertion start timing θ1 to 60°, the goal arrival timing θ2 at which the weft yarn 4 reaches the goal to 230°, and the rotational speed N of the loom to 600 rpm.
After the necessary data are input, the reed width L0 (210 cm), which relates to the weft insertion length for each pick, the remaining weft-insertion length (brake position) L1 (105 cm), the amount of operation of the weft brake 42 of the weft brake device 40 (stroke) SL (11 mm), the diameter D of the drum 7 (700 mm), the brake-control ON timing θ4 (60°), and the brake-control OFF timing θ5 (250°) are shown on the screen of Fig. 4B, which is displayed when the setting of the values is finished.
The input data are stored in the memory 47 in the setter 31, transmitted via the port 39 and the control bus 38, converted into suitable signals by the signal converter 48 in the brake control unit 41, and fed to respective sections. The data including the remaining weft-insertion length L1, the reed width L0, the weft-insertion start timing θ1, the goal arrival timing θ2 at which the weft yarn 4 reaches the goal, the rotational speed N of the loom, and the drum diameter D are input to the delay time calculator 51. Provided that a gate signal S9 is obtained from the gate signal generator 55, the delay time calculator 51 performs calculations according to one of above items 5) or 6) derived from items 1) to 4), and thereby determines the brake start timing t3 or θ3. In addition, a delay time Td relative to a reference timing Ts is calculated and transmitted to the brake-start-timing signal generator 52.
The gate signal generator 55 outputs the gate signal S9 when all of the operation signal S1 of the fluid jet loom 1, the weft selection signal S8, and an ON/OFF timing signal S2 are input. Therefore, the brake control unit 41 which is not selected is not activated. The ON/OFF timing signal S2 is output from the timing signal generator 49 on the basis of the brake-control ON timing θ4 (60°) and the brake-control OFF timing θ5 (250°) set by the setter 31, and is at a high level in the period between 60° and 250° in terms of rotation angle θ. The brake-control ON timing θ4 (60°) and the brake-control OFF timing θ5 (250°) are both input. Although the brake-control OFF timing θ5 does not vary, the brake-control ON timing θ4 is corrected in the direction of time delay on the basis of the delay time Td, and accordingly the brake start timing t3 or θ3 is obtained.
Fig. 5 is a graph showing the insertion characteristic of the weft yarn 4 and the above-mentioned signals, where the horizontal axis shows the time t and the vertical axis shows the insertion length L of the weft yarn 4. The ideal insertion characteristic of the weft yarn 4 is linear, as shown in Fig. 2. However, in practice, the insertion characteristic is shown by the two-dot chain curve because of deceleration during the insertion.
As shown in Fig. 5, in this example, the reference timing Ts is the same as the weft-insertion start timing t1 or θ1 and the brake-control ON timing θ4 (60°), and the time corresponding to the delay time Td after the weft-insertion start timing t1 or θ1 corresponds to the brake start timing t3 or θ3. The brake start timing t3 or θ3 corresponds to the time at which the front end of the weft yarn 4 is inserted by the weft-insertion length L2 and the remaining weft-insertion length is L1, and to the rising edge of an operation command signal S6. The brake-control OFF timing θ5 (250°) corresponds to the falling edge of the operation command signal S6.
The amount of operation (stroke) SL of the weft brake 42 is transmitted to the drive circuit 57 to determine the stroke of forward and reverse rotation of the actuator 43, such as a pulse motor. Normally, the weft brake 42 rotates forward by a stroke designated by the brake control ON/OFF timing signal S2 in an early stage of the operation period (60° to 250°). Then, the weft brake 42 rotates in the reverse direction in a later stage of the operation period by the same stroke as that of the forward rotation, and thereby returns to the original state.
The data including the brake-control ON timing θ4 and the brake-control OFF timing θ5 are transmitted to the timing signal generator 49. In order to set the brake control period between the brake-control ON timing θ4 and the brake-control OFF timing θ5, the timing signal generator 49 generates the ON/OFF timing signal S2 that is at a high level during this period, and transmits this signal to the pulse generators 53 and 54 and the gate signal generator 55.
The pulse generator 53 generates a pulse signal S4 at the rising edge (60°) of the ON/OFF timing signal S2 representing the brake control period, and thereby activates the brake-start-timing signal generator 52. The brake-start-timing signal generator 52 generates a brake-start-timing signal S3 when the delay time Td elapses, that is, at the brake start timing t3 or θ3, and sets the flip-flop 56. Accordingly, the drive circuit 57 is activated by the operation command signal S6 output from the flip-flop 56. The pulse generator 54 generates a pulse signal S5 at a falling edge (250°) of the ON/OFF timing signal S2 representing the brake control period, and thereby resets the flip-flop 56. Accordingly, the operation command signal S6 activates the drive circuit 57 in a period between the brake start timing t3 or θ3 and the falling edge (250°) of the ON/OFF timing signal S2.
The drive circuit 57 sets the brake state by rotating the motor 34 forward by a stroke designated in an early stage of the brake period, and maintains this state during the brake period. Then, the drive circuit 57 rotates the motor 34 in the reverse direction by the same stroke as that of the forward rotation, and thereby returns the motor 34 to the original state. Accordingly, the weft brake device 40 rotates the weft brake 42 to bend the weft yarn 4 in the period between the brake start timing t3 or θ3 and the falling edge (250°) of the ON/OFF timing signal S2, so that the weft yarn 4 receives the braking force and decelerates. Thus, the weft yarn 4 receives the braking force when the remaining weft-insertion length becomes L1. Accordingly, even when the retaining pin 8 suddenly retains the weft yarn 4 on the yarn-winding surface of the drum 7 after the brake start timing t3 or θ3, sudden increase of the tension applied to the weft yarn 4 can be suppressed. Accordingly, the breakage of the weft yarn 4 at this time can be reliably prevented.
As described above, the brake start timing t3 or θ3 of the weft brake device 40 is determined by calculation based on the equation including the weft-insertion velocity in the weft-insertion period, the value L0 relating to the weft insertion length for each pick, and the remaining weft-insertion length L1. The weft-insertion velocity in the weft insertion period is determined from the relationship between the difference between the weft-insertion start timing t1 or θ1 and the goal arrival timing t2 or θ2 and the value L0 relating to the weft insertion length for each pick. To be accurate, the value L0 relating to the weft insertion length for each pick is equal to the release length for each pick in the weft measuring-and-storing device 5. However, an equivalent value which is less accurate but is more familiar to the operator and more convenient (e.g., a reed width) is used in practice.
Since the remaining weft-insertion length L1 is used as an input value for changing the brake start timing t3 or θ3 of the weft brake device 40, the operator can easily recognize the input value and adjust the brake start timing. In addition, the brake start timing t3 or θ3 of the weft brake 42 is automatically determined by calculation when the remaining weft-insertion length L1 is input. Therefore, the operator can quickly set a desired brake state for the weft yarn 4. Thus, the weft yarn 4 receives the braking force when the remaining weft-insertion length becomes L1. Accordingly, even when the retaining pin 8 suddenly retains the weft yarn 4 on the yarn-winding surface of the drum 7 after the brake start timing t3 or θ3, sudden increase of the tension applied to the weft yarn 4 can be suppressed. Accordingly, the breakage of the weft yarn 4 at this time can be reliably prevented.
The remaining weft-insertion length L1 used for changing the brake start timing t3 or θ3 of the weft brake device 40 directly corresponds to the brake period for the weft yarn 4. Therefore, when, for example, only the weaving width (reed width L0) is changed, the previous settings can be used without change unless it is necessary to change the brake period. Accordingly, the frequency of changing the setting is reduced compared to that in the known structure. If the brake start time of the weft brake device 40 is set in terms of time as in the known structure, the brake start time must be set again in accordance with the change in the reed width to obtain a desired brake period. Such a process can be omitted in the structure according to the present invention, and the task required when the reed width is changed is reduced.

Second Embodiment (Fig. 6)

Fig. 6 shows a brake control unit 41 according to a second embodiment. The brake control unit 41 shown in Fig. 6 reads out the brake start timing t3 or θ3 corresponding to the remaining weft-insertion length L1 of the weft yarn 4 from a data table (database) stored in advance instead of determining the brake start timing t3 or θ3 by calculation.
As is clear from the above-described calculation for obtaining the brake start timing t3 or θ3, when control conditions of the loom including the rotational speed N of the loom (600 rpm), the weft-insertion start timing θ1 (60°), the goal arrival timing θ2 (230°), and the reed width L0 (210 cm) are determined, a data table (database) of the brake start timing t3 or θ3 corresponding to the remaining weft-insertion length L1 can be set in advance as described in above items 5) and 6). The data table (database) can be corrected as necessary on the basis of the actual weft-insertion characteristic.
As shown in Fig. 6, in order to control the operation of the weft brake device 40, the brake control unit 41 includes a signal converter 48, a timing signal generator 49, a brake-start-timing determiner 50, a drive circuit 57, and an amplifier circuit 58. In order to store and read out the data table (database), the brake-start-timing determiner 50 includes a memory unit 60 and a brake-start-timing extractor 61 instead of the delay time calculator 51, the brake-start-timing signal generator 52, and the pulse generator 53 shown in Fig. 3.
In this embodiment, the memory unit 60 includes multiple data tables (databases) for various control conditions. Although data set in terms of time t described in item 5) may also be used, data set in terms of the rotation angle θ of the main shaft 28 described in item 6) is used in this embodiment.
When values are input, an operator operates the input unit 44 of the setter 31 to display the screen shown in Fig. 4A on the display 45. The operator touches ten keys/function keys 59 on the screen to set, for example, the reed width L0, which relates to the weft insertion length for each pick, to 210 cm, the remaining weft-insertion length (brake position) L1 to 105 cm, the amount of operation of the weft brake 42 of the weft brake device 40 (rotational stroke) SL to 11 mm, the drum diameter D to 700 mm, the brake-control ON timing θ4 to 60°, the brake-control OFF timing θ5 to 250°, the weft-insertion start timing θ1 to 60°, the goal arrival timing θ2 at which the weft yarn 4 reaches the goal to 230°, and the rotational speed N of the loom to 600 rpm.
After the necessary data are input, the reed width L0 (210 cm), which relates to the weft insertion length for each pick, the remaining weft-insertion length (brake position) L1 (105 cm), the amount of operation of the weft brake 42 of the weft brake device 40 (stroke) SL (11 mm), the drum diameter D (700 mm), the brake-control ON timing θ4 (60°), and the brake-control OFF timing θ5 (250°) are shown on the screen of Fig. 4B, which is displayed when the setting of the values is finished.
The input data are stored in the memory 47 in the setter 31, transmitted via the port 39 and the control bus 38, converted into suitable signals by the signal converter 48 in the brake control unit 41, and fed to respective sections. The data including the remaining weft-insertion length L1, the reed width L0, the weft-insertion start timing θ1, the goal arrival timing θ2 at which the weft yarn 4 reaches the goal, the rotational speed N of the loom, and the brake-control ON timing θ4 are input to the brake-start-timing extractor 61.
The brake-start-timing extractor 61 reads out the brake start timing θ3 corresponding to the input data from the database on the basis of the input data, and transmits the brake start timing θ3 to the timing signal generator 49. The amount of operation (stroke) SL of the weft brake 42 is transmitted to the drive circuit 57 to determine the stroke of forward and reverse rotation of the drive motor 34.
The data of the brake-control OFF timing θ5 is transmitted to the timing signal generator 49. In order to set the brake control period between the brake start timing θ3 and the brake-control OFF timing θ5, the timing signal generator 49 generates an operation command signal S6 that is at a high level during this period, and the drive circuit 57 is activated with the operation command signal S6. The drive circuit 57 rotates the actuator 43 forward by a designated stroke in the brake period, and then rotates the actuator 43 in the reverse direction by the same stroke as that of the forward rotation. Accordingly, the actuator 43 returns to the original state.
Accordingly, the weft brake device 40 bends the weft yarn 4 with the weft brake 42 in the period between the brake start timing θ3 and the brake-control OFF timing θ5, so that the weft yarn 4 receives the braking force and decelerates. Thus, the weft yarn 4 receives the braking force when the remaining weft-insertion length becomes L1. Accordingly, even when the retaining pin 8 suddenly retains the weft yarn 4 on the yarn-winding surface of the drum 7, sudden increase of the tension applied to the weft yarn 4 can be suppressed. Accordingly, the breakage of the weft yarn 4 at this time can be reliably prevented.
As described above, the brake control unit 41 according to the second embodiment stores the database including the brake start timing θ3 corresponding to the remaining weft-insertion length L1 and the loom's control conditions which influence the weft-insertion velocity. The brake start timing θ3 corresponding to the input remaining weft-insertion length L1 is searched for, and the brake start timing is determined accordingly. Therefore, compared to the first embodiment in which calculation is performed for each weft insertion, the load placed on the brake-start-timing determiner 50 is reduced and the timing can be determined more quickly.

Third Embodiment (Figs. 7 and 8)

Fig. 7 shows a brake control unit 41 according to a third embodiment. The brake control unit 41 shown in Fig. 7 determines the brake start timing t3 or θ3 by calculation in synchronization with the releasing operation of the weft measuring-and-storing device 5. Accordingly, a brake-start-timing determiner 50 includes a delay time calculator 51 and a brake-start-timing signal generator 52 similar to that shown in Fig. 3, and also includes a release-signal-cycle calculator 62.
Fig. 8 is a graph showing a quadric curve representing the insertion characteristic of the weft yarn 4 and the above-mentioned signals, where the horizontal axis shows the time t and the vertical axis shows the insertion length L of the weft yarn 4. The insertion lengths corresponding to 1, 2, and 3 turns in the weft measuring-and-storing device 5 and those corresponding to 1/4, 3/4, 5/4, 7/4, 9/4, and 11/4 turns are indicated on the axis of insertion length L. The numbers of turns indicated by fractions correspond to a release signal S7 of the weft yarn 4 generated twice in each turn by the release sensor 26, and the denominator corresponds to a shift angle 90° (1/4 of the circumference of the weft-winding surface) between the position of the retaining pin 8 and that of the release sensor 26. When the reed width L0 relating to the weft insertion length for each pick is 210 cm and three turns of weft is released for each pick, the drum diameter D is determined as 700 mm.
During the operation, provided that a gate signal S9 is obtained, the release-signal-cycle calculator 62 receives the pulse release signal S7 of the weft yarn 4 and transmits the signal to the delay time calculator 51. Since multicolor weft insertion is performed, a weft selection signal S8 functions as the input condition. More specifically, if the weft selection signal S8 is not input, that is, if the corresponding weft yarn 4 is not selected, the brake-start-timing determiner 50 is not activated. The release-signal-cycle calculator 62 receives the release signal S7 detected by the release sensor 26 while the gate signal S9 is input, and outputs the signal to the delay time calculator 51.
Similar to the release-signal-cycle calculator 62, provided that the gate signal S9 is obtained, the delay time calculator 51 receives the release signal S7, the remaining weft-insertion length L1, the reed width L0, the drum diameter D, the number of turns n by which the weft is released, and the attachment position information PS of the release sensor 26, and determines a reference pulse number np. In addition, the delay time calculator 51 also calculates the delay time Td and transmits the calculated delay time Td to the brake-start-timing signal generator 52. The reference pulse number np is determined from the number of pulses n of the release signal S7 generated at the time corresponding to a length (distance) of (L0 - L1). In the example of Fig. 8, (L0 - L1) = L2 = 105 cm is satisfied, and accordingly the reference pulse number np is determined as 3. The delay time Td is the time since the pulse corresponding to the reference pulse number np (= 3) is received, that is, since the third pulse is received. From the equation representing the relationship among the weft-insertion velocity v immediately before (weft-insertion velocity v between the second and third pulses (v = L4/T2)), the delay time Td, and the lengths (distances) L2, L4, and L5, the delay time Td is calculated as Td = (L2 - L5) × (T2/L4) = (17.5/35) × T2 = 0.5 × T2.
The brake-start-timing signal generator 52 generates a pulse brake-start-timing signal S3 when the delay time Td elapses after the pulse corresponding to the reference pulse number np = 3, that is, the third pulse is received. The flip-flop 56 is set by the brake-start-timing signal S3, and the drive circuit 57 is activated by an operation command signal S6 output from the flip-flop 56. The pulse generator 54 generates a pulse signal S5 at a falling edge (250°) of the ON/OFF timing signal S2 representing the brake control period, and thereby resets the flip-flop 56. Accordingly, the operation command signal S6 activates the drive circuit 57 in a period between the brake start timing t3 or θ3 and the falling edge (250°) of the ON/OFF timing signal S2.
When the brake control is performed on the basis of the release signal S7 as described above, even if the release status or the insertion status of the weft yarn 4 largely varies each time the weft insertion is performed, the brake control is carried out in accordance with the variation. Therefore, the brake suitable for the release status and the insertion status of the weft yarn 4 can be performed.
As described above, the weft-insertion velocity v is obtained in accordance with the generation cycle of the release signal S7 of the weft yarn 4. However, the weft-insertion velocity v may also be detected each time the weft insertion is performed using another detection signal obtained by detecting the insertion status of the weft yarn 4. For example, the weft-insertion velocity v may be detected using one or more weft sensors disposed in the shed 17 between the weft yarns 16. In addition, although the release sensor 26 which generates the reference timing Ts is disposed near the weft measuring-and-storing device 5, the present invention is not limited to this. For example, signals from the weft sensors disposed in the shed for detecting the weft yarn 4 being inserted may also be used.
In all of the above-described embodiments, the remaining weft-insertion length L1 is determined on the basis of the distance from the front end of the weft yarn 4. However, instead of the remaining weft-insertion length, a remaining weft pull-out length from the weft measuring-and-storing device 5 may also be set. In addition, with regard to the unit of length input to the setter 31, a percentage with respect to the total length may also be set instead of using the unit of actual length (cm or mm). For example, when the total length (reed width L0) is 100, the remaining weft-insertion length L1 may be set to 20 in terms of the ratio between them.
The determined brake start timing t3 or θ3 may include the time or angle for correcting a response delay (circuit delay time between the signal input and the generation of the braking force by the actuator 43 (e.g. a motor)). Alternatively, the circuit may be structured so as to compensate for the response delay. The weft brake device 40 may perform the control in terms of either time or the rotation angle of the main shaft 28.
The present invention may also be applied to water jet looms in addition to air jet loom.

Claims

A method for controlling a weft brake device (40) in a fluid jet loom (1) including the weft brake device (40) and a weft measuring-and-storing device (5) of a weft-winding type having a retractable retaining pin (8), the weft brake device (40) being disposed between the weft measuring-and-storing device (5) and a main nozzle (10) for weft insertion and applying a braking force to a weft yarn (4) pulled out from the weft measuring-and-storing device (5), wherein, in a weft insertion process, the retaining pin (8) retracts to release the weft yarn (4) stored in the weft measuring-and-storing device (5) in a wound state, the weft brake device (40) applies the braking force to the weft yarn (4) at a brake start timing (t3, θ3) while the released weft yarn (4) is being inserted into a shed (17) between warp yarns (16) by a jet from the main nozzle (10), and the retaining pin (8) projects to stop the weft yarn (4) and thereby finishes the weft insertion process, the method being characterized in that:
a remaining weft-insertion length (L1) to a final weft arrival position at the time when braking starts is input beforehand to the weft brake device (40) as an input value, and the weft brake device (40) determines the brake start timing (t3, θ3) on the basis of the input remaining weft-insertion length (L1) and applies the braking force to the weft yarn (4) at the determined brake start timing (t3, θ3) while the fluid jet loom (1) is in operation.
A weft brake device (40) for use in a fluid jet loom (1) including the weft brake device (40) and a weft measuring-and-storing device (5) of a weft-winding type having a retractable retaining pin (8), the weft brake device (40) being disposed between the weft measuring-and-storing device (5) and a main nozzle (10) for weft insertion and applying a braking force to a weft yarn (4) pulled out from the weft measuring-and-storing device (5), wherein, in the weft insertion process, the retaining pin (8) retracts to release the weft yarn (4) stored in the weft measuring-and-storing device (5) in a wound state, the weft brake device (40) applies the braking force to the weft yarn (4) at a brake start timing (t3, θ3) while the released weft yarn (4) is being inserted into a shed (17) between warp yarns (16) by a jet from the main nozzle (10), and the retaining pin (8) projects to stop the weft yarn (4) and thereby finishes the weft insertion process, the weft brake device (40) being characterized by comprising:
a setter (31) for inputting a remaining weft-insertion length (L1) to a final weft arrival position at the time when braking starts as an input value;

a brake-start-timing determiner (50) for determining the brake start timing (t3, θ3) on the basis of the input remaining weft-insertion length (L1) input by the setter (31); and

control means (49, 56, 57) for applying the braking force to the weft yarn (4) at the determined brake start timing (t3, θ3) while the fluid jet loom (1) is in operation.
The weft brake device (40) according to Claim 2, wherein the final weft arrival position is set to a position between a selvedge position at a downstream side in a weft-insertion direction and a final weft arrival end position, and wherein the remaining weft-insertion length (L1) input by the setter (31) is set to a distance between a front end of the weft yarn (4) and the final weft arrival position at the time when braking starts.
The weft brake device (40) according to Claim 2, wherein the final weft arrival position is set to a final weft arrival end position, and wherein the remaining weft-insertion length (L1) input by the setter (31) is set to a remaining release length of the weft measuring-and-storing device (5) at the time when braking starts.
The weft brake device (40) according to one of Claims 2 to 4, wherein the remaining weft-insertion length (L1) input by the setter (31) is set to one of an actual length and a percentage with respect to a weft release length for each pick of weft insertion.
The weft brake device (40) according to one of Claims 2 to 5, wherein the brake-start-timing determiner (50) determines the brake start timing (t3, θ3) by calculation based on a formula including an insertion velocity of the weft yarn (4) in a weft insertion period, a value (L0) relating to a weft insertion length for each pick, and the remaining weft-insertion length (L1).
The weft brake device (40) according to one of Claims 2 to 5, wherein the brake-start-timing determiner (50) includes a memory unit (60) storing a database including the brake start timing (t3, θ3) with respect to control conditions of the fluid jet loom (1) and the remaining weft-insertion length (L1), and wherein the brake-start-timing determiner (50) determines the brake start timing (t3, θ3) corresponding to the control conditions of the fluid jet loom (1) and the remaining weft-insertion length (L1) by searching the memory unit (60).