Thread selecting device

Abstract: In the thread selecting device, a link is connected to an arm, moving up and down in synchronism with the action of a weaving machine, and the link pivots when the arm moves up and down. Pivoting links lift a plurality of threads via a plurality of knives, the thread lift distance varying according to the pivot angle of the arm. By providing a mechanism which moves the connection point between the arm and the link along an arc having a radius equal to the length of the arm, the lift distance of the thread may be varied without varying the lift position of the thread.

Description: FIELD OF THE INVENTION This invention relates to an improvement of a thread selecting device such as a jacquard used in a weaving machine. BACKGROUND OF THE INVENTION When a weaving machine forms a pattern, openings are for example formed in threads, and transverse threads are passed through the openings. To form openings, threads are held in raised positions, for which purpose a thread selecting device such as a jacquard which selects specific threads from a plurality of threads according to the pattern, and lifts them up, is installed above the weaving machine. The thread selecting device works in synchronism with the operating cycles of the weaving machine, for example via a link mechanism. The link mechanism raises a bar via an eccentric arm and an oscillating link connected to the arm. A plurality of knives connected to the bar individually lift needles connected to the threads. The raised needles are selectively held in their raised positions via hooks in response to solenoids. The threads are selected by selecting energizing solenoids. The openings in the threads vary depending on the weaving machine, and even for the same weaving machine, the required openings also vary according to thread type and stress setting for the threads used in a cloth. The thread openings correspond to the lifting distances of the needles, i.e. to the rising/falling distance of the knives. Such a thread selecting device for weaving machines is known from the prior art document WO 94/25654. Said thread selecting device comprising a first arm moving up and down in synchronism with an action of said weaving machine, said arm having a length, a first link connected to said first arm at a first connection point and pivoting about a predetermined point according to the moving up and down of said first arm, first means for moving said first connection point along a first arc, a second link connected to a second arm and pivoting about a predetermined point, and a knife which is raised and lowered according to the pivoting of said first link and said second link. Each joint with a link arm may for example comprise an oblong hole and a link pin passing through the hole, this link pin being fixed by a bolt in one of a plurality of positions permitted by the oblong hole. When the fixing position is varied, the distance between the link pin and link pivot point varies, and the angular range through which the link pivots, varies. In this way, the rising/falling distance of the knife is varied. When the fixing position of the link pin is shifted, however, the link pivot angle varies for the same position of the eccentric arm. As a result the raised position of the knife, i.e. the lift position of the needle, also varies, however if the position of the hook does not change, it is difficult for the hook to attach the needle when the needle lift position largely varies. The needle lift position may be corrected by providing a length adjusting mechanism on the bar, however the correction must be performed each time the lift distance changes, and if such a mechanism is provided, the construction of the thread selecting device is rendered more complex. It is an objective of the present invention to provide a thread selecting device for a weaving machine as indicated above being simple in construction. It is therefore an object of this invention to make it unnecessary to correct a needle lift position when the thread lift. distance changes. It is a further object of this invention to vary a thread lift distance by a simple construction. In order to achieve the above objects, this invention provides a thread selecting device for a weaving machine according to claim 1. The device comprises a first arm moving up and down in synchronism with an action of the weaving machine, this arm having a length, a first link connected to the first arm at a first connection point and pivoting about a predetermined point according to the moving up and down of the first arm, and a knife which is raised and lowered according to the pivoting of the first link. Further provided is a first mechanism for moving the first connection point along a first arc having a radius equal to the length of the first arm. It is preferable that the first connection point is a first pin attached to the first arm, and the first mechanism comprises a first oblong hole formed along the first arc in the first link so as to guide the first pin along the first arc and a first fixing mechanism for selectively fixing the first pin in a plurality of positions along the first oblong hole. It is also preferable that the device further comprises a second link connected to the first link via a second arm, the second link pivoting about a predetermined point according to the pivoting of the first link, a knife which is raised and lowered according to the pivoting of the second link and a second mechanism for moving a second connection point connecting the second arm and the first link along a second arc having a radius equal to the length of the second arm. It is also preferable that the second connection point is a second pin attached to the second arm, and the second mechanism comprises a second oblong hole formed along the second arc in the first link so as to guide the second pin along the second arc and a second fixing mechanism for selectively fixing the second pin in a plurality of positions along the second oblong hole. The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an enlarged lateral view of a part of a link mechanism according to this invention. Fig. 2 is an enlarged vertical sectional view of a link and eccentric arm according to this invention. Fig. 3 is a schematic front view of a jacquard and a weaving machine to which this invention is applied. Fig. 4 is a lateral view of the link mechanism and a jacquard according to this invention. Fig. 5 is a front view of a knife, needle and hook for the purpose of describing thread selection by the jacquard. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to Fig. 3 of the drawings, a thread selecting device operates in synchronism with the rotation of a main shaft 30 of a weaving machine. The rotation of the shaft 30 causes an eccentric arm 32 of the jacquard 2 shown in Fig. 4 to move up and down via a shaft 34. In the jacquard 2, the up/down motion of the arm 32 is transmitted via a link pin 51, a first link 33, an arm 36 and a second link 35 to bars 37 and 38 so as to move the bars up and down together. A plurality of knives 7A are connected to the bars 37, 38 via a link member 39, these knives rising and falling together with the bars 37, 38. Another link mechanism of similar construction is provided in parallel with this link mechanism in order to raise and lower knives 7B. The difference of these link mechanisms is that the eccentric position of the eccentric arm is shifted by 180° with respect to each other so that the knives 7A, 7B rise and fall alternately due to the rotation of the shaft 34. The knives 7A, 7B respectively push up needles 4A, 4B as shown in Fig. 5. One thread 8 is connected to the two needles 4A, 4B via a pulley 41. A hook 6A engages with the needle 4A pushed up by the knife 7A according to the energization of a solenoid, and the needle 4A is thereby held in its raised position. When the other needle 4B is then pushed up by the knife 7B, both the needles are in their raised positions, so the thread 8 connected to the lower ends of the needles 4A, 4B is lifted up. As the thread 8 is lifted up, an opening is formed in the thread 8, and a transverse thread is passed through the opening. However when a solenoid 5 is not energized, a hook 40 does not engage with the needle 4A, and the needle 4A descends together with the knife 7A as it descends. In other words, when the needle 4B rises, the needle 4A descends instead and the thread 8 is not lifted. Hence, by selectively energizing the solenoids 5, desired threads 8 are selected so as to weave a desired pattern. The above is a summary of the jacquard 2 which applies this invention. Next, the features of this invention will be described with reference to Fig. 1 and Fig. 2 of the drawings. The first link 33 is supported free to pivot about a point 53, the arm 32 being connected to the link 33 via the link pin 51. The arm 36 is connected via a link pin 61, the arm 36 being connected to the second link 35. The link pin 51 is supported free to rotate about the upper end of the arm 32, and passes through an arc-shaped oblong hole 60 formed in the first link 33. The center line of the hole 60 is set so that it coincides with the path of the radius R 1 of the arm 32 in the lowered position. A plurality of pairs of bolt holes 62 are formed around the hole 60. A flange 51A is formed an end of the link pin 51, the link pin 51 being fixed in any desired position along the hole 60 by bolts 55 which screw into bolt holes 62 through the flange 51A as shown in Fig. 2. The link pin 61 is supported free to rotate about one end of the arm 36, and passes through an arc-shaped oblong hole 66 formed in the first link 33. The center line of the hole 66 is set so that it coincides with the path of the radius R 2 of the arm 36 in the raised position of the knife 7A. A plurality of pairs of bolt holes 64 are formed around the hole 66. A flange 61A is formed at an end of the link pin 61, the link pin 61 being fixed in any desired position along the hole 66 by bolts 63 which screw into bolt holes 64 through the flange 61A as shown in Fig. 2. In this thread selecting device, in the lowered position of the arm 32, the first link 33 has rotated to its extreme anticlockwise position, the second link has rotated to its extreme clockwise position, and the knife 7A is in its raised position. When it is desired for example to increase the rising/falling distance of the knife 7A, the bolt 55 is removed, the link pin 51 is moved to the right of Fig. 1 along the hole 60, and is then again fixed to the link 33 by the bolt 55. The distance between the point 53 and the link pin 51 is then shorter, and the pivot angle of the first link 33 for the same up/down position of the arm 32, increases. The rising/falling distance of the knife 7A therefore increases. Even when the fixing position of the link pin 51 varies, the link pin 51 moves along an arc corresponding to the radius of the arm 32 in its lowered position. The rotation position of the link 33 in the lowered position of the arm 32 therefore does not change, only the rotation position of the link 33 in the raised position of the arm 32 moving in a clockwise direction. The raised position of the knife 7A does not vary, and the rising/falling distance of the knife 7A increases due to the downward shift of the lowered position of the knife 7A. Consequently, the positional relationship between the needle 4A driven by the knife 7A and the hook 6A driven by the solenoid 5 does not change, and only the lift distance of the thread 8 varies without any effect on the selecting of the needle 4A by the hook 6A. The stop position of the link pin 61 is moved in the same way. For example, when the stop position of the link pin 61 is moved toward the top of Fig. 1, the distance between the point 53 and link pin 61 increases, and the shift distance of the arm 36 for the same range of rotation of the first link 33, increases. The rotation range of the second link 35 therefore also increases, and the rising/falling distance of the knife 7A driven up and down via the link 35 increases. However, as the stop position of the link pin 61 moves along an arc corresponding to the radius of the arm 36 in the raised position of the knife 7A, the rotation angle of the link 35 in the raised position of the knife 7A does not change even when the stop position of the link pin 61 changes, and the rising/falling distance of the knife 7A increases due to the downward movement of the lower position of the knife 7A. Consequently, the positional relationship between the needle 4A driven by the knife 7A and the hook 6A driven by the solenoid 5 does not change, and only the lift distance of the thread 8 varies without any effect on the selecting of the needle 4A by the hook 6A. In the aforesaid thread selecting device, the rising/falling distances of the knife 7A driven by the first link 33 and of the knife 7A driven by the second link must be arranged to be identical. The rising/falling distance of the knife 7A driven by the first link 33 is therefore determined by setting the stop position of the link pin 51, and the stop position of the link pin 61 is determined such that the rising/falling distance of the knife 7A driven by the second link 35 is the same. Accordingly, although this invention has been shown and described in terms of the preferred embodiments thereof, it is not to be considered as limited by any of the perhaps quite fortuitous details of the embodiments, or of the drawings, but only by the terms of the appended claims, which follow.

Claims: A thread selecting device (2) for a weaving machine (3) comprising a first arm (32) moving up and down in synchronism with an action of said weaving machine (3), said arm (32) having a length, a first link (33) connected to said first arm (32) at a first connection point (51) and pivoting about a predetermined point (53) according to the moving up and down of said first arm (32), first means (55, 60, 62) for moving said first connection point (51) along a first arc, a second link (35) connected to a second arm (36) and pivoting about a predetermined point, and a knife (7A) which is raised and lowered according to the pivoting of said first link (33) and said second link (35), characterized in that said first link (33) is connected with said second arm (36) at a second connection point (61), and second means (63, 66, 64) are provided for moving said second connection point (61) along a second arc, said second arm (36) is connecting the first link (33) and the second link (35), and said first arc having a radius (R 1 ) equal to the length of said first arm (32) and said second arc having a radius (R 2 ) equal to the length of said second arm (36), wherein the up and down portion of said first arm (32) is transmitted via a first link pin (51), said first link (33), said second arm (36) and said second link (35) to bars (37, 38) so as to move the bars (37, 38) up and down together with a plurality of knifes (7A) which are connected to said bars (37, 38) via a link member (39), these knifes (7A) rising and falling together with the bars (37, 38). A thread selecting device according to claim 1, characterized in that said first connection point (51) is a first pin (51) attached to said first arm (32), and said first means (55, 60, 62) comprises a first oblong hole (60) formed along said first arc in said first link (33) so as to guide said first pin (51) along said first arc and first fixing means (55, 62) for selectively fixing said first pin (51) in a plurality of positions along said first oblong hole (60). A thread selecting device according to claim 1 or 2, characterized in that said second connection point (61) is a second pin (61) attached to said second arm (36), and said second means (63, 64, 66) comprises a second oblong hole (66) formed along said second arc in said first link (33) so as to guide said second pin (61) along said second arc and second fixing means (63, 64) for selectively fixing said second pin (61) in a plurality of positions along said second oblong hole (66).

Inventors: MUTO SHIGEYUKI, SUNOHARA IKUO, MUTO, SHIGEYUKI, SUNOHARA, IKUO, Muto, Shigeyuki c/o Kayaba Kogyo K. K., Sunohara, Ikuo, c/o Kayaba Kogyo K. K.
Applicants: KAYABA INDUSTRY CO LTD, KAYABA KOGYO KABUSHIKI KAISHA
Application year: 1996
Main classification: D03C3
IPC codes: D03C3