EP0879909B1

EP0879909B1 - Loom having linear motor-driven shedding motion mechanism

Info

Publication number: EP0879909B1
Application number: EP19980108242
Authority: EP
Inventors: Tatsuya Uematsu; Masaki Takasan; Yochi Saito
Original assignee: Toyota Industries Corp
Current assignee: Toyota Industries Corp
Priority date: 1997-05-08
Filing date: 1998-05-06
Publication date: 2002-09-04
Anticipated expiration: 2018-05-06
Also published as: DE69807572T2; EP1215318A2; DE69807572D1; EP0879909A1; JPH10310949A

Description

The present invention relates to a loom having a plurality of linear motor-driven shedding motion mechanisms so configured as to maintain the conventional arraying pitch between heald frames.

Description of the Related Art

A conventional shedding motion of a loom is performed by fixing wires etc. on heald frames and converting the power of an ordinary motor, etc. to a vertical movement using a mechanical mechanism. In such a mechanical mechanism, cams, etc. are used to convert the rotary movement of motors, etc. to a vertical movement. However, once the vertical movement has been adjusted, the control of the shedding motion is fixed. Accordingly, the conventional method causes inconvenience when changing the kind of cloth to be woven, since it is not easy to modify the requirements of the shedding motion.
Today, thanks to the advancements in electronic control technology, the shedding motion of a loom can be controlled by a computer, the speed and timing of the vertical movements of the heald frames can be freely modified, and thereby a loom which can weave various kinds of cloth easily, can be implemented.
Under these circumstances, it was proposed that the heald frames of a loom should be driven using linear motors, and that the shedding motion could be easily controlled using a computer. The details of a shedding motion mechanism using such linear motors are described, for example, in Japanese Patent Publication (Tokkouhei) No. 4-70414. The proposed shedding motion mechanism using linear motors is described below.
Figs.1A and 1B explain a conventional linear motor-driven shedding motion mechanism.
In Fig.1A, movement elements 44-1 and 44-2 for linear motors are provided on sidestays 43-1 and 43-2 on each side of a heald frame 42. Particularly, the movement elements 44-1 and 44-2 are provided on the side of the sidestays 43-1 and 43-2 facing the guide frames 41-1 and 41-2. The guide frames 41-1 and 41-2 are provided with grooves, and the heald frame 42 is set in the grooves. At the bottom of the grooves, stators 45-1 and 45-2 are provided facing the movement elements 44-1 and 44-2 provided on the heald frame 42. The stators 45-1 and 45-2 are provided with coils to generate a magnetic field. The movement elements 44-1 and 44-2 attached to the sidestays 43-1 and 43-2 of the heald frame 42 are made of aluminum.
When a current is passed through the coils of the stators 45-1 and 45-2, eddy currents are generated in the movement elements 44-1 and 44-2, the movement elements 44-1 and 44-2 receive motive power by controlling the current in the coils, and the heald frame 24 starts moving vertically.
Fig.1B explains an alternative configuration of the conventional linear motor-driven shedding motion mechanism.
In this configuration too, a heald frame 46 and guide frames 47-1 and 47-2 being the basic components of the shedding motion mechanism are provided. A part of each of the sidestays 43-1 and 43-2 of the heald frame 46 is set in grooves provided in the guide frames 47-1 and 47-2 to provide vertical movement.
The difference in configuration from Fig.1A is that in place of forming a linear motor by providing the heald frame 46, and the guide frames 47-1 and 47-2 with stators and movement elements, linear motors 48-1 and 48-2 are added as shown in Fig.1B. The movement elements of the linear motors 48-1 and 48-2 are attached to supports 49-1 and 49-2, and when the linear motors 48-1 and 48-2 operate, the supports 49-1 and 49-2 move vertically. By mounting these supports 49-1 and 49-2 onto the heald frame 46, the heald frame 46 also shifts vertically to perform the shedding motion. In this case, the linear motors 48-1 and 48-2 are typically cylinder type linear motors.
Generally speaking, when weaving cloth, the number of the heald frames provided in a loom is from 4 to 16. It is in order to weave various kinds of patterns into a piece of cloth that a plurality of heald frames are provided. In the case of weaving a piece of cloth which is broad in width, one set of warp threads have to be supported by two heald frames; since the tension of a warp thread becomes high.
In this way, a plurality of heald frames have to be used arrayed in parallel in an actual loom, and the pitch between the heald frames is usually set to be approximately 15mm. The angle formed between the warp threads when one heald frame shifts upward and the other heald frame shifts downward, is approximately 30 to 35 degrees. This angle is set so that a weft thread may pass through between upper sheds and lower sheds easily. When 16 heald frames are provided, the stroke (length of a vertical movement) of a heald frame located nearest to the front of the loom is approximately 50mm, and the stroke of a heald frame located farthest from the front of the loom is approximately 140mm. However, when the stroke becomes 140mm, the propulsive force of the motors for driving the heald frame reaches its limit. In this case, if the stroke needs to be further extended, motors of disproportionately large size becomes necessary. If the pitch between heald frames become wider, the stroke of the heald frame located farthest from the front of the loom becomes too long, and thereby motors with an enormously large propulsive force become necessary, which is not practical.
Therefore, it is necessary to maintain the pitch between heald frames at approximately 15mm. On the other hand, when configuring a shedding motion mechanism using such linear motors as described above, the maximum thickness of the motors is considered to be over 30 millimeters, even if a linear motor exclusively used for a shedding motion mechanism is developed. Also, when the pitch of heald frames is extended to over 30 millimeters, matching the thickness of the linear motors, the stroke of a heald frame located the farthest from the front of a loom out of a plurality of heald frames becomes far longer than 140mm, then a larger propulsive force becomes necessary, and then larger linear motors become necessary, which creates a vicious circle. Accordingly, such a configuration that the pitch between heald frames may be maintained at approximately 15mm under the conditions of using linear motors with a thickness of over 30 millimeters, becomes necessary.
The post-published document EP 0 795 635 A1 discloses a configuration similar to Fig. 1B wherein a plurality of heald frames is vertically supported by linear motors. The linear motors of adjacent heald frames are horizontally shifted.

Summary of the Invention

It is an object of the present invention to provide a loom having a linear motor-driven shedding motion mechanism so configured as to maintain the conventional pitch between heald frames.
This object is solved by a loom according to claim 1, the invention is further developed by the features defined in subclaim 2.
In a loom having the above-mentioned configuration, since shedding motion mechanism using linear motors having a width thicker than the pitch between heald frames can be used, while maintaining the conventional intervals at which a shedding motion mechanism or heald frames are arrayed, a loom in which the shedding motion can be controlled more easily than with a conventional method, by making the most of the advantages of linear motors, can be implemented.
Since a conventional pitch between shedding motion mechanisms or heald frames can be maintained, the stroke of the vertical movement of a heald frame located the farthest from the front of a loom out of the arrayed heald frames can be reduced to a minimum, and thereby the necessary propulsive force of the linear motors can be reduced to a minimum.

Brief Description of the Drawings

Figs.1A and 1B explain conventional linear motor-driven shedding motion mechanisms.
Figs.2A through 2C show an embodiment of the heald frame arrays of this invention.
Fig.3 shows an comparative example (not claimed) of the arrays in the case of a shedding motion mechanism as shown in Fig.1B.
Figs.4A through 4D show alternatives (not claimed) of the arrays of linear motors for a linear motor-driven shedding motion mechanism having a configuration as shown in Fig.3.

Description of the Preferred Embodiments

Figs.2A through 2C show an embodiment of the heald frame arrays of this invention.
Fig.2A shows an example of the configuration in the case where heald frames are arrayed diagonally displaced. In Fig.2A each heald frame 2 is mounted on a guide frame 5 so as to move vertically, in each end of the heald frame 2 movement elements 4 for forming linear motors are provided, and the movement elements 4 together with stators 3 provided in the guide frame 5 compose a linear motor 1. The difference in configuration between a linear motor shown in Fig.2A and a linear motor shown in Fig.1A, is that in the configuration shown in Fig.2A, the front or rear of a sidestay is used as the effective area for generating propulsive force of the movement elements 4 of a linear motor. Since by adopting such a configuration a wide effective area for generating propulsive force of a linear motor can be secured, the size of the linear motor can be reduced to a minimum. However, even if such a configuration is adopted, the maximum thickness of the linear motor is considered to be over 30 millimeters. That is, since the propulsive force of a linear motor is determined by the width of the effective area for generating propulsive force, and the thickness is not related with the propulsive force closely, the linear motor can be made thinner. However, when the linear motor becomes too thin, a generated magnetic field saturates the yoke of the linear motor, the propulsive force is reduced, and thereby the coreloss becomes high due to hysteresis. When the coreloss becomes high, the power efficiency of the linear motor falls, and the linear motor becomes heated, which is not desirable.
Thus, in Fig.2A, to keep the pitch between heald frames 2 approximately 15mm while using linear motors 1 with a thickness of over 30 millimeters, shedding motion mechanisms comprising a linear motor 1, a heald frame 2 and a guide frame 5 are arrayed shifted a little horizontally from each other. According to this configuration, since linear motors 1 comprising movement elements 4 and stators 3 do not interfere with each other, the pitch between heald frames 2 can be made narrower.
Fig.2B shows an alternative heald frame arrangement for preventing linear motors from interfering with each other. In this case, heald frames 2 with different horizontal lengths for each shedding motion mechanism are arrayed. In this way, the pitch between heald frames can also be made narrow, since linear motors 1 do not interfere with each other. However, in the case of Fig.2B, the farther from the front of a loom that a heald frame is located, the longer the horizontal length of the heald frame becomes. Accordingly, the farther from the front of a loom a heald frame is located, the larger the size of linear motors for driving the heald frame tends to become. Further, the farther from the front of a loom a heald frame is located, the longer the stroke of the vertical movement of the heald frame is required to be. Accordingly, the farther from the front of a loom a heald frame is located, the more necessary it becomes to use linear motors with a larger propulsive force. For this reason, in contrast with Fig.2B, if the horizontally longest heald frame and the horizontally shortest heald frame are located at the front and the back of the loom, respectively, the necessary propulsive force of the linear motors can be reduced to a minimum, since the stroke of the horizontally longest heald frame 2 can be made shorter.
Fig.2C shows an alternative of a heald frame arrangement for arraying shedding motion mechanisms with different horizontal lengths, comprising heald frames 2, guide frames 5 and linear motors 1. According to the configuration shown in Fig.2C, a shedding motion mechanism with a plurality of heald frames 2 can be configured without significantly extending the horizontal length, by preparing only two kinds of heald frames with different horizontal lengths. That is, even if many heald frames 2 are used, the overall horizontal length of all of the heald frames is no longer than the horizontal length of the heald frame with the longest horizontal length. Since the horizontal length of the shedding motion mechanism to be used to actually weave cloth does not change even if the number of heald frames 2 increases, the size of heald frames 2 can be reduced to a minimum.
Fig.3 shows an comparative example (not claimed) of the arrays in the case of a shedding motion mechanism as shown in Fig.1B.
Although the number of linear motors mounted on one heald frame is two in Fig.1B, in Fig.3 four linear motors are mounted on one heald frame 11. By doubling the number of linear motors for driving one heald frame 11 from two to four, the propulsive force needed for each linear motor can be halved, and the size can also be halved. As described with reference to Fig.1B, when linear motors 14 are driven with the heald frame 11 supported from the bottom, the heald frame 11 is so mounted as to be able to vertically slide in a guide 13 provided on a guide frame 12. Movement elements 14b of the linear motors 14 are connected to the bottom of the heald frame 11, and are so structured as to move vertically by the force received from the stators 14a.
By increasing the number of linear motors 14 mounted on one heald frame 11, the size of each linear motor 14 is reduced, and the positions of linear motors 14 to be mounted on two adjacent heald frames are so shifted that heald frames 11 may be closely arrayed with each other. That is, linear motors 14 drawn with solid lines and linear motors 16 drawn with broken lines in the front view of Fig.3 are linear motors for driving a heald frame located nearest to the front and linear motors for driving a heald frame located immediately behind the heald frame nearest to the front, respectively. As clearly seen from Fig.3, the linear motors 16 for driving the second nearest to the front heald frame are so located as to avoid the linear motors 14 for driving the nearest to the front heald frame.
In this way, when two or more heald frames are arrayed, as shown in the side view of Fig.3, the linear motors for driving the second nearest to the front heald frame are so located as to avoid the linear motors for driving the nearest to the front heald frame, the linear motors for driving the third nearest to the front heald frame are so located as to avoid the linear motors for driving the second nearest to the front heald frame, and so on. By repeating such an array, many heald frames can be arrayed while maintaining a heald frame pitch 15 at approximately 15mm.
Figs.4A through 4D show alternatives (not claimed) of the arrays of linear motors for a linear motor-driven shedding motion mechanism having a configuration as shown in Fig.3.
Fig.4A shows a configuration (not claimed) in which linear motors 30-1 and 30-2 for driving a heald frame are mounted vertically. In this case, the linear motors for driving a heald frame located at the back are so located as to avoid the linear motors for driving a heald frame located at the front. That is, for example, linear motors 31-1 and 31-2, and linear motors 32-1 and 32-2 are for driving the second heald frame and the third heald frame, respectively.
As can be clearly seen from the side view of Fig.4A, heald frames can be closely arrayed with each other by locating the linear motors for driving a heald frame located behind so as to avoid the linear motors for driving a heald frame in front.
Fig.4B shows an example (not claimed) of a shedding motion mechanism in which a configuration of driving a heald frame from the bottom and a configuration of driving a heald frame from the top are alternately arrayed.
As can be clearly seen from the side view of Fig.4B, linear motors 33 are mounted on the bottom of a heald frame located the nearest to the front, and linear motors 34 are mounted on the top of a heald frame located the second nearest to the front. In this way, by alternately mounting linear motors for driving heald frames at the top and then at the bottom, heald frames can be closely located to each other without the linear motors for driving adjacent heald frames interfering with each other.
Fig.4C shows a configuration (not claimed) of arraying the linear motors for driving adjacent heald frames in a zigzag pattern. That is, linear motors 35 for driving a heald frame located the nearest to the front and linear motors 36 for driving a heald frame located the second nearest to the front, are positioned offset from each other both horizontally and vertically, with respect to the floor on which the shedding motion mechanism or a loom consisting of these shedding motion mechanisms are installed. As can be clearly seen from the side view of Fig.4C, linear motors for driving the heald frames located the third nearest to the front and subsequent frames, are arrayed in the same way the first two heald frames. Since by arraying in this way, linear motors can be driven in a position near to each end of a heald frame, heald frames can be stably driven. In the case of Fig.4A, with the linear motors 32-1 and 32-2, there is a possibility that the mounting positions of these linear motors may come near the center of a heald frame. In this case the array tends to be unstable because the horizontally long heald frames are driven only near the center, however, in the configuration shown in Fig.4C, this problem can be avoided.
Fig.4D shows a configuration (not claimed) in which linear motors are mounted both vertically and arrayed in a zigzag pattern. That is, on a heald frame located the nearest to the front, linear motors 37-1 and 37-2 are mounted vertically. On a heald frame located immediately behind the heald frame nearest to the front, linear motors 38-1 and 38-2 are also mounted vertically. However, the respective mounting positions of the linear motors 38-1 and 38-2 are shifted both horizontally and vertically with respect to the floor, from the corresponding mounting position of linear motors 37-1 and 37-2, so that the linear motors 38-1 and 38-2 may not interfere with the linear motors 37-1 and 37-2. Since by arraying in this way, linear motors can be made not to interfere with each other, adjacent heald frames can be closely arrayed. Since in the same way as in Fig.4C, linear motors can be mounted near the end of each heald frame, the heald frames can be stably driven.
According to the present invention, even if in a shedding motion mechanism, rather large linear motors are used to drive heald frames, the pitch between a provided plurality of heald frames can be maintained at a conventional pitch.
Accordingly, the length of the stroke in the shedding motion of a heald frame located the farthest from the front can be maintained at the same level, and thereby the necessary propulsive force and size of the linear motors can be reduced to a minimum.

Claims

A loom comprising an array of a plurality of heald frames (2) respectively vertically driven along guide frames (5) by linear motors (1) each consisting of a stator (3) and a movement-element (4), respectively, wherein one of said stator (3) and said movement-element (4) is provided in a sidestay at an horizontal end of said heald frame (2) and the respectively other of said stator (3) and said movement-element (4) is provided in said guide frame (5),
characterised in that
said heald frames (2) have different horizontal lengths so that said linear motors (1) do not interfere with each other.
A loom according to claim 1,
characterized in that
said heald frames (2) are arrayed horizontally shifted.