Shedding system

Abstract: A shedding system is disclosed having a plurality of heddles (1) supported at one end thereof connected to top ends of piston rods (8) of a plurality of pneumatic cylinders. Driven by the pneumatic cylinders, the heddles (1) are moved vertically upwardly and downwardly to shift the threads passing through the heddles (1) so as to form the shed. A method of joining a fabric by a woven seam is also disclosed which uses the above-mentioned system to form the shed in an array of the threads of an interweaving piece.

Description: The present invention relates to a system for forming the shed in a seam weaving portion for joining the ends of a fabric and to a method of forming a woven seam using the system. As known in the art, the ends of a fabric are joined together to form an endless fabric or the peripheral edge of a fabric is joined to that of another fabric to form a larger piece of fabric. In most of the conventional methods, the ends of the fabric or the peripheral edges are overlapped with each other and then sewn together or bonded together. However, the above-mentioned conventional method of joining together fabric can not be employed for papermaking fabrics, such as a sheet forming fabric. This is because such papermaking fabrics require a uniform structure and a uniform filtration space. Otherwise, the resultant paper product formed on the fabric is nonuniform in thickness and causes undesirable marking to occur. In addition, fabrics for use in the manufacture of nonwoven fabrics must have a uniform structure in view of touch, laminatability and uniformity. Further, the above-mentioned conventional method can not be used for fabrics which are for covering the sludge in a pressure dewatering process. This is because leakage of the sludge occurs due to the presence of a nonuniform filtering area in adjoining ends of a fabric to face each other, removing transversal or weft threads in one of the joining ends over a seam width to leave longitudinal or warp threads alone, introducing the warp threads into a fabric structure of the other joining end, and cutting and removing parallel warp threads of the other joining end. However, this method is not practically available unless the fabric is a coarse mesh. In this connection, it has been considered to join the ends of a fabric by weaving, in adjoining portions, a fabric which is similar in structure to the main body of the fabric. According to this prior method, threads which serve as warp threads corresponding to weft threads of the main body of the fabric are separated vertically upwardly to form the shed in a seam weaving portion. On the other hand, threads in both ends of the fabric to be joined are introduced into the shed as weft threads. Thus, a woven seam is formed. However, in order to effectively and mechanically perform the shed formation for weaving, there exists no other means superior to the known Jacquard device. However, the Jacquard device generally used in seaming machines requires longitudinal needles, transversal needles, knives, pattern cards, cylinders for receiving the pattern cards and inevitably has a large size. It is therefore inappropriate to use the Jacquard device in forming a woven seam which is narrow. In sheet forming fabric, a wide variety of fabric structures are used and multi-layer fabrics have recently been put into use. In this connection, the number of heddles inevitably increases. This results in further increase in size of the shedding system. Thus, such a conventional shedding system is not satisfactory for use in a seam weaving operation. In addition, the Jacquard device has heddles each of which is supported at both upper and lower end thereof and moved for the shed formation. With this structure, it is impossible to separately pick up an individual one of the heddles. When a large number of the heddles are arranged in a seam weaving portion which is narrow, it is difficult to thread the heddles surrounded by a mass of heddle supporting members standing together closely. If a thread is snapped during the seam weaving operation, it is extremely difficult to find the particular heddle in question and to thread the particular heddle for recovery. In particular, the Jacquard device encounters difficulty in treating multi-layer fabrics, such as double-layer fabrics and triple-layer fabrics, which have recently been put into use. As is known in the art the term "shed" means the path through and perpendicular to the warp in a loom. The shed is formed by raising some warp threads by means of their harness while others are left down. The shuttle press through the shed to insert the filling. The term "shedding" means the operation of forming a shed in the weaving process. Also as is known in the textile art, the heddle is a cord, round steel wire, or thin flat steel strip, or equivalent with loop or eye near the center through which one or more warp threads pass on the loom so that their movement may be controlled in weaving. The heddles conventionally are held at both ends by the harness frame. They control the weave pattern and shed as the harnesses are raised and lowered during weaving. As a result of a study to overcome the above-mentioned disadvantages, it was determined that the shedding system used in seaming machines must be modified in order to improve the seam weaving speed and to form a woven seam of a wide variety of fabric structures. According to this invention, there is provided a shedding system in a seaming machine comprising a plurality of heddles, characterized in that, each heddle is supported at only one end, and has an eye at the other end, in that each heddle is individually coupled to a piston rod of a plurality of pneumatic cylinders, and in that it further comprises a plurality of electromagnetic valves individually connected to said, pneumatic cylinder, and a control unit for producing a signal to operate said electromagnetic valves, said heddles being moved vertically upwardly and downwardly by stroke movement of said pneumatic cylinders to thereby form a shed in an array of threads, said threads individually passing through eyes of said heddles. In a more detailed aspect, the shedding system of the invention also includes a cooling fan for cooling the electromagnetic valves and a control unit having a memory for memorizing a fabric structure. Each of the heddles used in the present invention is a solid body formed of metal or plastics. The heddles can be molded into a shape having an arcuate section or an undulating section. Any suitable metal or plastic having the properties necessary to perform this function can be used to make the heddle. Another object of the invention is to provide a method of joining the ends of a fabric woven seam to form an endless fabric using the shedding system of the present invention. According to the present invention therefore there is provided a method of joining the ends of a fabric by a woven seam to form an endless fabric, comprising the steps of: (a) preparing an interweaving piece which is made of the same kind of fabric as said fabric to be joined and which has a width corresponding to that of said woven seam and a length longer than the transversal width of said fabric to be joined, said interweaving piece having one longitudinal end area with a fabric structure left therein and a remaining area containing weft threads alone with warp threads removed therefrom, (b) removing weft threads in both end zones of said fabric over width substantially equal to that of said woven seam to form interweaving portions comprising warp threads alone, (c) holding said interweaving portions on a weaving table so that said interweaving portions are faced to each other at a distance equal to the width of said woven seam from each other to define a space therebetween, and placing said interweaving piece in said space so that said fabric structure left at said one longitudinal end area is positioned at one transversal end of said interweaving portions, (d) making said weft threads of said interweaving piece pass through eyes of a plurality of heddles of a shedding system as claimed in any one of the preceding claims, (e) attaching weights to other ends of said weft threads of said interweaving piece to apply tensile force to said weft threads, (f) operating electromagnetic valves connected to said pneumatic cylinders by a signal from a control unit, (g) moving said heddles vertically upwardly and downwardly by stroke movement of said pneumatic cylinders to thereby form the shed in a array of said weft threads passing through said eyes of said heddles, and (h) introducing said warp threads of said interweaving portions into the shed to form said woven seam. In another embodiment of the invention, the method of joining the ends of a fabric by a woven seam to form an endless fabric is carried out are described above, except that the warp threads, instead of the weft threads, of the interweaving piece are passed through eyes of the plurality of heddles. In all other respects, this second embodiment is the same as the first method described above. According to a more detailed aspect of the invention, and in both method embodiments described above the threads of the interweaving portions to be introduced into the shed have a crimp similar to that of the original threads which are introduced into the shed when the fabric to be joined is initially woven. Still further, the woven seam can be made to have a fabric structure similar to that of the other portion of the fabric by the use of a memory which is included in the control unit of the shedding system and which is for memorizing the fabric structure. In yet another aspect of the invention, weighted strings are connected to the weft threads of the interweaving piece passing through the eyes of the heddles to apply tensile force to the weft threads during the weaving operation of the fabric structure. The present invention will be further described by way of example with reference to the accompanying drawings, wherein Fig. 1 is a perspective view of a shedding system of the invention; Fig. 2 is a schematic view of a pneumatic cylinder connected to the heddle; Fig. 3 is a schematic plan view of an interweaving piece; Fig. 4 is a partial perspective view of the weaving apparatus of the invention illustrating the interweaving piece held on a weaving table; Fig. 5 is a partial perspective view of the weaving apparatus of the invention showing how the seam weaving method is carried out; and Fig. 6 is a plan view showing the top ends of warp threads interwoven according to the invention. This invention is characterized in that the heddles are supported at one end thereof and are independent from one another. With this structure, it is possible to separately pick up a desired single one of the heddles among a mass of the heddles. Accordingly, even if a large number of the heddles are arranged in a narrow limited area, the threading operation is not impeded by other heddles at all. In the case when a thread is snapped in operation of the weaving operation, recovery is readily performed because the particular heddle in question can be easily selected from the mass of heddles in the apparatus. Specifically, the heddles are swingable because they are supported at only one end thereof. Therefore, the mass of the heddles can be manually pushed aside to select the particular heddle in question for recovery. Alternatively, the particular heddle in question can be automatically protruded vertically upwardly or downwardly. Referring now to the drawings, Fig.1 is a perspective view of a shedding system according to this invention. Each heddle 1 has an eye 5 and is connected to a piston rod of each pneumatic cylinder and are positioned in the vicinity of an end of a case 7. However, the pneumatic cylinders may be positioned at a center of the case. The case 7 may be a box or a frame. The control unit, not shown, consists of a computer and a memory. The memory stores the data of fabric pattern or structure of the area to be shedded. The computer reads the prescribed data stored in the memory and produces the signals each of which designates each of magnetic valves 3 being opened or closed. The control unit may be positioned inside or outside the case 7. Such a control unit is well known in the art, and any suitable control unit can be used for the purposes of the present invention. The electromagnetic valves 3 are individually connected to the pneumatic cylinders and drive the pneumatic cylinders in response to a signal from the conventional control unit (not shown). Cooling fans 4 are for removing heat generated by operation of the pneumatic cylinders. The cooling fans may be arranged at a side surface. A mobile guide 6 is attached to the case. The case is mounted through the guide on a guide rail of a weaving table to be movable along the weaving table. Fig. 2 shows the pneumatic cylinder connected to the heddle. The heddle is coupled to a piston rod 8 of the pneumatic cylinder. Fig. 3 shows an interweaving piece 9. The interweaving piece has at one end thereof a fabric structure comprising weft threads 10 and warp threads 11. In a remaining portion of the interweaving piece all warp threads are removed to leave the weft threads 10 with a crimp. The interweaving piece has a width corresponding to that of a woven seam and a length longer than the transversal width of the fabric to be joined. Fig. 4 shows the interweaving piece held on a weaving table 18. The fabric structure remaining in the interweaving piece is fixed to the weaving table. The weft threads with a crimp are extended through the eyes of the heddles and subjected to tensile force by weights 12 connected to one ends of the weft threads. The case 7 is mounted on the mobile guide rail of the weaving table. Fig. 5 is a view illustrating the seam weaving method according to this invention. In a seam weaving portion, end portions 14 of the fabric to be joined are arranged to face each other on the weaving table 13. The interweaving piece comprising the weft threads is placed between the end portions. The case 7 is mounted on the guide rail of the weaving table. The weft threads of the interweaving piece are made to pass through the eyes of the heddles. The weft threads are removed from the end portions of the fabric to be joined over the width equal to that of the woven seam to leave the warp threads with a crimp. When the heddles are moved by the pneumatic cylinders, the weft threads passing through the heddles are shifted to form the shed, like the warp threads in an ordinary weaving process. Like ordinary weft threads, the warp threads of the end portions of the fabric are successively introduced into the shed to form a fabric structure. At this time, the movement of the heddles is controlled so as to form the fabric structure similar to that of the main body of the fabric. As is clear from a woven seam illustrated at the leftmost portion in Fig. 5, the weft threads 10 of the interweaving piece serve as the warp threads in the seam weaving operation while the warp threads 15 of the end portions of the fabric serve as the weft threads. Fig. 6 shows the top ends of the warp threads which are interwoven. The top ends of the warp threads face each other with the weft threads interposed therebetween. The facing positions are dispersed to form no linear alignment. With this structure, any problems of marking are prevented. Thus, a fabric structure completely similar to that of the main body of the fabric is formed. In the conventional Jacquard device, the heddles are supported at both upper and lower ends thereof. Accordingly, the heddles can not be manually pushed aside. On the other hand, it is possible to make a particular heddle be upwardly protruded among a mass of the heddles. However, the particular heddle is not swingable because it is supported at both upper and lower ends. Furthermore, the supporting members of the other heddles closely stand and surround the particular heddle. As a result, threading or recovery operation is extremely difficult. Thus, in the Jacquard device, it is impossible to arrange a concentrated mass of the individual heddles in a narrow area. The following describes the seam weaving method according to this invention. At both ends of a fabric to be joined the weft threads are removed from end zones over a predetermined width to prepare interweaving portions exclusively comprising warp threads with a crimp. The interweaving portions with the warp threads alone are folded back and placed on a weaving table to face each other with a predetermined distance left therebetween. An interweaving piece is made of the same kind of fabric as the fabric to be joined and has a width corresponding to that of a woven seam and a length longer than the transversal width of the fabric to be joined. The interweaving piece has a fabric structure at one end thereof with warp threads retained therein while a remaining area of the interweaving piece contains only weft threads with a crimp with warp threads removed therefrom. The interweaving piece is fixedly located in a space defined between the interweaving portions facing each other so that the one end with the fabric structure is positioned at a seam weaving starting side and the weft threads are parallel to the weaving table. The weft threads of the interweaving piece are made to pass through the eyes of the heddles. The weft threads are subjected to tensile force which is produced by weights attached to one end of the weft threads. The heddles are individually connected to pneumatic cylinders. The heddles are supported at one ends coupled to the top ends of piston rods of the pneumatic cylinders. Electromagnetic valves of the pneumatic cylinders are operated in response to a signal delivered from a control unit and move the heddles vertically upwardly and downwardly. Consequently, the weft threads of the interweaving piece passing through the heddles are shifted vertically upwardly and downwardly to form the shed. The warp threads of both end portions of the fabric to be joined are introduced into the shed. Thus, seam weaving operation is carried out to integrally join the both end portions by forming a fabric. As described, a woven seam has a structure similar to the other portion of the fabric. In this seam weaving operation, the weft threads of the interweaving piece are shifted by heddles to form the shed while the warp threads of the main body of the fabric are introduced into the shed. In comparison, when the original fabric is woven, the warp threads are shifted by heddles to form the shed while the weft threads are introduced into the shed. In the foregoing description, the interweaving piece is prepared by removing the warp thread to leave the weft threads alone. Alternatively, seam weaving operation can also be carried out with the interweaving piece prepared by removing the warp threads to leave the weft threads alone. In this case, the warp threads are removed from the both ends of the fabric to be joined over the width corresponding to that of the woven seam to form the interweaving portion comprising the weft threads alone. Use may also be made of a combination of an interweaving piece prepared by the weft threads alone and interweaving portions formed by the warp threads alone. Since the fabric is formed by warp threads and weft threads, the seam weaving operation can be carried out whichever thread is introduced into the shed. The pneumatic cylinders to be used have a diameter between 2.5mm-5mm. The pneumatic cylinders are driven by electromagnetic valves which are operated in response to a signal from a control unit having a memory for memorizing a structure of a woven seam. Since heat is generated during the operation of the pneumatic cylinder, it is preferable to provide a cooling device such as a fan. Example 1 The system in Fig. 1 according to this invention was used to join the fabric consisting of single warp threads and double weft threads as shown in Table 1. A woven seam was formed by 150mm per hour. As compared with a conventional manual seam weaving in which a woven seam was formed by 60mm per hour, the efficiency is almost three time high. Warp Thread Diameter (mm) 0.62 Number (per inch) 45 Upper Weft Thread Diameter (mm) 0.58 Number (per inch) 16 Lower Weft Thread Diameter (mm) 0.58 Number (per inch) 16 In the shedding system according to this invention, the heddles are connected in one-to-one correspondence to pneumatic cylinders and moved thereby. Since the pneumatic cylinders are very small, a large number of the pneumatic cylinders can be arranged in a seam weaving portion which is narrow. The pneumatic cylinders are driven by electromagnetic valves to cause stroke movement. Accordingly, the shedding system is very compact and can be arranged in the upper or the lower portion of the seam weaving portion. According to this invention, the heddles are supported at one ends thereof so that shedding system for seam weaving operation is small-sized and recovery of a thread snapping accident is facilitated. It is possible to readily and accurately form a woven seam having a desired structure. Further variations and modifications of the invention will be apparent to those skilled in the art from the foregoing and are intended to be encompassed by the claims appended hereto.

Claims: A shedding system in a seaming machine, comprising a plurality of heddles (1), characterized in that each heddle (1) is supported at only one end, and has an eye (5) at the other end, in that each heddle (1) is individually coupled to a piston rod (8) of a plurality of pneumatic cylinders, and in that it further comprises a plurality of electromagnetic valves (3) individually connected to said pneumatic cylinder, and a control unit for producing a signal to operate said electromagnetic valves (3), said heddles (1) being moved vertically upwardly and downwardly by stroke movement of said pneumatic cylinders (8) to thereby form a shed in an array of threads, said threads individually passing through eyes (5) of said heddles. A shedding system as claimed in claim 1, further comprising a cooling fan (4) for cooling said electromagnetic valves (3). A shedding system as claimed in claim 1 or 2 wherein said control unit comprises a memory for memorizing a fabric structure. A shedding system as claimed in any one of claims 1 to 3, wherein each of said heddles (1) comprises a solid body formed of metal or plastics. A shedding system as claimed in any one of the preceding claims, wherein said heddles (1) are made of a metal material or a plastic material moulded into a shape having an arcuate section or an undulating section. A method of joining the ends of a fabric by a woven seam to form an endless fabric, comprising the steps of: (a) preparing an interweaving piece (9) which is made of the same kind of fabric as said fabric to be joined and which has a width corresponding to that of said woven seam and a length longer than the transversal width of said fabric to be joined, said interweaving piece having one longitudinal end area with a fabric structure left therein and a remaining area containing weft threads alone with warp threads removed therefrom, (b) removing weft threads in both end zones of said fabric over width substantially equal to that of said woven seam to form interweaving portions comprising warp threads alone, (c) holding said interweaving portions on a weaving table (18) so that said interweaving portions are faced to each other at a distance equal to the width of said woven seam from each other to define a space therebetween, and placing said interweaving piece in said space so that said fabric structure left at said one longitudinal end area is positioned at one transversal end of said interweaving portions, (d) making said weft threads of said interweaving piece pass through eyes (5) of a plurality of heddles (1) of a shedding system or claimed in any one of the preceding claims, (e) attaching weights (12) to other ends of said weft threads of said interweaving piece to apply tensile force to said weft threads, (f) operating electromagnetic valves (3) connected to said pneumatic cylinders by a signal from a control unit, (g) moving said heddles (1) vertically upwardly and downwardly by stroke movement of said pneumatic cylinders to thereby form the shed in a array of said weft threads passing through said eyes (5) of said heddles (1), and (h) introducing said warp threads of said interweaving portions into the shed to form said woven seam. A method of joining the ends of a fabric by a woven seam to form an endless fabric, comprising the steps of: (a) preparing an interweaving piece (9) which is made of the same kind of fabric as said fabric to be joined and which has a width corresponding to that of said woven seam and a length longer than the transversal width of said fabric to be joined, said interweaving piece (9) having one longitudinal end area with a fabric structure left therein and a remaining area containing warp threads alone with weft threads removed therefrom, (b) removing warp threads in both end zones of said fabric over a width substantially equal to that of said woven seam to form interweaving portions comprising weft threads alone, (c) holding said interweaving portions on a weaving table (18) so that said interweaving portions are faced to each other at a distance equal to the width of said woven seam from each other to define a space therebetween, and placing said interweaving piece (9) in said space so that said fabric structure left at said one longitudinal end area is positioned at one transversal end of said interweaving portions, (d) making said warp threads of said interweaving piece pass through eyes (5) of a plurality of heddles (1) of a shedding system as claimed in any one of claims 1 to 5, (e) attaching weights (12) to other ends of said warp threads of said interweaving piece to apply tensile force to said warp threads, (f) operating electromagnetic valves (3) connected to said pneumatic cylinders by a signal from a control unit, (g) moving said heddles (1) vertically upwardly and downwardly by stroke movement of said pneumatic cylinders to thereby form the shed in an array of said warp threads passing through said eyes (5) of said heddles (1), and (h) introducing said weft threads of said interweaving portions into the shed to form said woven seam. A method as claimed in claim 6 or 7 wherein the threads of said interweaving portions to be introduced into the shed have a crimp similar to that of the original threads which are introduced into the shed when said fabric to be joined is initially woven. A method as claimed in any one of claims 6 to 8 wherein said woven seam is made to have a fabric structure similar to that of the other portion of said fabric by the use of a memory which is included in said control unit of said shedding system and which is for memorizing said fabric structure. A method as claimed in any one of claims 6 to 9, wherein weighted strings are connected to said weft threads of said interweaving piece passing through said eyes (5) of said heddles (1) to apply tensile force to said weft threads during weaving operation of said fabric structure.

Inventors: SANO SEIJI, SANO, SEIJI
Applicants: NIPPON FILCON KK, NIPPON FILCON CO., LTD.
Application year: 1992
Main classification: D03C3
IPC codes: D03C13, D06H5, D21F1, D03C3