Classifications

• • D—TEXTILES; PAPER
  • D05—SEWING; EMBROIDERING; TUFTING
  • D05B—SEWING
  • D05B65/00—Devices for severing the needle or lower thread
• • D—TEXTILES; PAPER
  • D05—SEWING; EMBROIDERING; TUFTING
  • D05B—SEWING
  • D05B57/00—Loop takers, e.g. loopers
• • D—TEXTILES; PAPER
  • D05—SEWING; EMBROIDERING; TUFTING
  • D05D—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES D05B AND D05C, RELATING TO SEWING, EMBROIDERING AND TUFTING
  • D05D2207/00—Use of special elements
  • D05D2207/02—Pneumatic or hydraulic devices
  • D05D2207/04—Suction or blowing devices

Definitions

• a device for shortening the end of the needle thread is provided at the start of sewing.
• This additional device has a thread catcher arm that runs into a catch hook and is fastened to a carrier wheel of the thread cutting device that rotates about a vertical axis and carries two cutting knives.
• a spring-loaded thread clamp is arranged on the underside of the throat plate, which is normally open and closed by a cam surface formed on the thread catcher arm can be.
• the carrier wheel is given a rotary movement which is opposite to the rotary movement occurring at the start of a thread cutting process.
• the invention has for its object to provide a method and an apparatus for shortening the end of the needle thread at the start of sewing, which can be implemented with little technical effort.
• the task is characterized by the characteristic features of the
• the position of the recess or hole is selected so that the thread catching position of the thread catcher for thread cutting at the seam end and for shortening the needle thread end at the beginning of the seam is the same.
• the drive mechanism of the thread cutting device contains a control cam that can be driven by the sewing machine, it is expedient in the event that the thread catcher is to be held in an intermediate position by a locking member that can be engaged and disengaged, to form one of the gear members resiliently, e.g. B. in the form of a telescopic handlebar according to claim 19.
• the thread cutting device which has a drive mechanism provided with a control cam, is assigned a needle thread clamp
• Fig. 12 is an enlarged view of a thread clamp
• the thread cutting device 22 described above differs from the thread cutting device disclosed in the aforementioned DE 3244996 C2 only in that the leaf spring 44 and the pneumatic cylinder 48 with the stop plate 50 are additionally arranged in it.
• the sewing machine executes the second stitch formation cycle.
• the pneumatic cylinder 34 remains pressurized, whereby the joint 47 is held in contact with the stop plate 50 and the thread catcher 23 in the thread clamping position. Since the needle thread end NE is held in place during the second stitch formation process, the looper can pull out a complete needle thread loop, guide it around the bobbin housing and thereby grasp the free end of the looper thread G. The subsequent upward movement of the thread transmitter 5 then the needle thread loop is pulled back and the first thread linkage of the needle and looper thread in the material is tightened.
• the sewing machine is briefly stopped again and then the pneumatic cylinder 48 is reversed, which consequently pulls the stop plate 50 out of the pivot path of the joint 47.
• the piston, not shown, of the pneumatic cylinder 34 which is still acted upon, is moved back into its end position and the thread catcher 23 is pivoted back into its starting position according to FIGS. 2 and 3.
• part of the needle thread end NE is cut off by the interaction of the cutting edge 43 and the edge 39.
• the shortened needle thread end at the beginning of the seam after thread cutting has the same length as the thread ends that remain on the material after thread cutting at the seam end.
• a locking piece 71 is fastened, which is designed and arranged in such a way that it forms an axially acting movement lock for the control lever 66 only in its rest position remote from the control cam 61, but from that into the working position pivoted control lever 66 can be driven under.
• a transversely projecting pin 78 is arranged which extends through an elongated hole 79 in the sleeve 75.
• a compression spring 80 arranged in the sleeve 75 holds the stop piece 76 in the starting position shown in FIG. 5, in which the pin 78 bears against the left end of the elongated hole 79.
• the thread catcher 23 can be used in both different cutting processes, that is to say both when cutting the thread at the end of a seam and when shortening it
• the compressed air stream emerging from the end piece 82 now presses the loop leg NV on the supply side after the drop from the thread guide plate 18 in the direction of the front of the gripper 15, the intensity of the compressed air flow being selected so large that the loop leg NV on the supply side in the region of the movement path of the thread catcher 23 in essentially occupies the same position as at the time when both loop legs NN and NV still rest against the thread guide plate 18.
• the electromagnet assigned to the thread cutting device 60 is briefly switched on again and immediately afterwards the drive motor of the sewing machine.
• a sloping section of the control cam 62 moves the shaft 64 to the left from the starting position according to FIG. 5 via the control lever 66.
• This movement is transmitted via the telescopic link 73 to the angle lever 29 and, as a result, the thread catcher 23 is moved from its initial position into the thread catching position shown in FIGS. 10 and 11.
• the compressed air stream emerging from the end piece ensures that both loop legs NN and NV lie on the side of the thread catcher 23 on which the barb 36 is located.
• the pneumatic cylinder 48 is acted upon and the stop plate 50 is moved into an upper position in which it is then in the pivoting path of the joint 47.
• the control groove 62 is designed such that it has moved the thread catcher 23 back towards its starting position at the time of the top dead center of the thread transmitter 5. Due to the return movement of the thread catcher 23, the needle thread end NE is taken along by the barb 36 and pulled under the leaf spring 44.
• the stop plate 50 located in the swivel path of the joint 47 has the effect that the thread catcher 23 cannot yet be fully retracted into its starting position at this time, but instead remains in the position shown in FIG. 12 in the same way as in the first exemplary embodiment and the needle thread end NE is clamped holds.
• the control lever 66 Since the control lever 66 is in positive connection with the control cam 61 during the engagement of the roller pin 65 in the control groove 62, the control lever 66 is pushed back into its initial position despite the stop plate 50 standing in the pivoting path of the joint 47.
• the rod 77 moves with the stop piece 76 relative to the held sleeve 75, whereby the compression spring 80 is tensioned.
• the control segment 63 pivots the pawl 69, as a result of which the switch-on lever (not shown) is released and returns to its starting position.
• the spring 70 can push the control lever 66 away from the control cam 61, so that the roller pin 65 is lifted out of the control groove 62.
• the tensioned compression spring 80 holds the control lever 66 in lateral contact with the locking piece 71.
• the gripper 15 pulls the end of the needle thread under the needle plate 14, as in the first exemplary embodiment, whereupon the thread loop dissolves and then only the portion of the needle thread that is in contact with the thread catcher 23 that previously held the loop leg NV on the supply side formed.
• the sewing machine is stopped briefly and the pneumatic cylinder 34 is reversed.
• the thread catcher 23 is moved back into its starting position, taking the needle thread end NE with it.
• the thread catcher 23 is completely moved back into the starting position without interruption and part of the needle thread end NE is cut off in the process. Because of the particularly short distance between the cutting edge 92 and the stitch hole 51, a particularly short needle thread end is achieved on the material to be sewn.
• Embodiment 4 The sewing machine shown in FIG. 13 is constructed identically to the sewing machine of the first embodiment, which is why the same reference numerals are used for the same components.
• the thread catcher 101 is only moved from its starting position into the thread catching position when the thread guide plate 18 has already removed from the two legs NN and NV of the needle thread loop or the legs NN and NV have fallen off the thread guide plate 18 are. This point in time is important because, in the case of a double lockstitch gripper rotating twice around a horizontal axis, the loop leg NN on the material side on the front of the bobbin case 20 and the loop leg NV on the back of the
• Bobbin case carrier 19 are moved past and both legs NN and NV after falling from the thread guide plate 18 thus run at different angles to the tap hole 51 of the throat plate 14.
• the thread catcher 101 with its separating tip 102 can be safely moved between the two loop legs NN and NV, the loop leg NN on the sewing material side being gripped by the barb 103 and fed to the cutting knife 113 when the thread catcher 101 is moved back, and the loop leg NV on the supply side can be kept away from the cutting knife 113 .
• the spring 70 acts as a compression spring and shifts the shaft 64 into the right end position shown in FIG. 18, in which the roller bolt 65 faces the control groove 62 when the sewing machine is in the needle low position.
• the trigger lever 67 is a Assigned spring-loaded switch lever, not shown, which can be actuated by an electromagnet, also not shown.
• a transversely projecting pin 78 is arranged in the stop piece 76 and extends through an elongated hole 79a in the sleeve 75.
• the elongated hole 79a is designed to be considerably longer than the corresponding elongated hole 79 in the second exemplary embodiment according to FIG. 5.
• a compression spring 80 arranged in the sleeve 75 holds the stop piece 76 in the starting position shown in FIG. 18, in which the pin 78 on left end of the elongated hole 79a abuts.
• the thread cutting device 140 is an additional one
• the needle 4 pulls a part of the loose needle thread end NE through the stitch hole 51 and the bore 108 of the thread catcher 101, whereupon the needle thread end NE is gripped by the hook tip 17 and completely pulled under the needle plate 14 , wherein the now freely hanging needle thread end NE runs through the bore 108.
• the stop plate 158 of the pneumatic cylinder 156 which is in the raised position, means that the thread catcher 101 cannot yet be fully retracted into its starting position at this point, but instead remains in a position corresponding to FIG. 12, in which its front section 111 is below the end piece the leaf spring 152 is located, together with it forms the thread clamp 153 and the edge 107 is still at a distance from the cutting edge of the cutting knife 151.
• the needle thread end NE coming from the tap hole 51 runs between the end of the leaf spring 152 and the front section 111 of the thread catcher 101 and is clamped between them. The needle thread end NE then runs from this clamping point below the
• the sewing machine executes the second stitch formation cycle. Since the needle thread end NE is held here, the hook 15 can guide a complete needle thread loop around the bobbin case and thereby grasp the free end of the hook thread G. By the subsequent upward movement of the thread transmitter 5 is then

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Sewing Machines And Sewing (AREA)

Priority Applications (3)

Applications Claiming Priority (4)

Publications (1)

Family

ID=25898917

Family Applications (1)

Country Status (6)

Cited By (2)

Families Citing this family (3)

Citations (5)

• 1991
  • 1991-06-01 DE DE4118008A patent/DE4118008A1/de active Granted
  • 1991-11-21 WO PCT/EP1991/002200 patent/WO1992009735A1/de active Application Filing
  • 1991-11-21 KR KR1019930701444A patent/KR100186838B1/ko not_active Expired - Fee Related
  • 1991-11-21 JP JP4500027A patent/JPH06503008A/ja active Pending
  • 1991-11-25 ES ES09102616A patent/ES2051177B1/es not_active Expired - Lifetime
  • 1991-11-28 IT ITTO910922A patent/IT1250228B/it active IP Right Grant

Patent Citations (5)

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