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
  • D05B65/00—Devices for severing the needle or lower thread
  • D05B65/02—Devices for severing the needle or lower thread controlled by the sewing mechanisms

Definitions

• the invention relates to a method and a device for cutting the needle and the looper thread on lockstitch sewing machines with gripper rotating in a horizontal plane and a feed device with a needle or top feed device by means of a thread cutting device, and a sewing machine for carrying out the method.
• DE 197 22 395 C1 discloses a method and an apparatus for severing the needle and the looper thread of the same type lockstitch sewing machines, wherein at the beginning of a thread cutting process provided with a cutting edge yarn catcher from a rest position to a reversal position and both a knife, as well as a clamp for the looper thread in a stitch hole of the throat plate adjacent cutting or receiving position are brought.
• For detecting the looper thread and the leg of the needle thread leading leg of the thread catcher is moved in a first step in an intermediate position in which the needle thread loop is pulled up to this.
• the thread catcher In a second step, the thread catcher is moved back to its rest position, during which movement of the thread catcher first withdrawn thread from the looper thread and inserted into the thread clamp. Thereafter, in the interaction of the thread catcher with the movable knife of the needle and the looper thread in the vicinity of the stitch hole are severed. Subsequently, the thread clamp and the knife are also moved back into their rest position, wherein the thread clamp subtracts further looper thread from the thread supply.
• the short length of the yarn side yarn ends is achieved primarily by not only the yarn catcher is brought from a rest position to a reversal position and from there back to the rest position, but also the knife from a remote from the stitch hole rest position in a stitch hole adjacent cutting position
• This also has a about a gripper shaft directed parallel shaft pivoting motion sensor, on its underside in the region of its front end a barb-shaped yarn thread catching part and a cutting edge part are formed.
• the movement of the knife is movable from its rest position along a trajectory extending through the needle path center in a reversal position.
• During the return movement of the movement knife to the rest position of the thread catching part first expands the needle thread loop formed by the gripper and then cuts through the needle and the hook thread in cooperation with a cutting blade, at the front end of a cutting edge portion is formed.
• it is also necessary to move the cutting blade from its rest position to its cutting position before performing the cutting process.
• the invention is therefore based on the object for lockstitch sewing machines with rotating in a horizontal plane gripper and a feed device with a needle or top feed device to provide a method for severing needle and looper thread, in conjunction with a simple trained, a thread catcher and having a knife having thread cutting device optimally short thread-side yarn ends results, but only requires the movement of either the thread catcher or the knife.
• the material to be moved by the feed by an amount and in this position of the material at ineffective feed device at least one further stitch (knotting stitch) to form it is first achieved that the seam formed despite the very It is very difficult to put up with short yarn ends on the thread side.
• the further measure to move the thread catcher from a laterally located behind the needle rest position along a running between the tap hole and the side wall of the gripper trajectory in a motion reversal position in which leading to the fabric leg of the needle thread loop together with the looper thread through the on Thread catcher trained barbs are detected the ability to guide the detected threads in the field of stitch pattern and cut there.
• the counter knife cooperating with the formed on the thread catcher cutting edges counter knife can be attached directly to the feed dog and thus arranged stationary, so that for between the Cutting edges of the thread catcher and the counter knife relative movement to be achieved, the movement of the yarn catcher is sufficient, and thus a drive for moving the counter knife is not required.
• a structurally favorable and space-saving solution for the movement of the thread catcher is achieved when it is pivotable about an axis parallel to the gripper shaft, and the trajectory of the catcher tip between the cam of the needle plate on the one hand and the needle hole of the feed dog on the other hand.
• the thread catcher can be made relatively flat and move within a horizontal plane above the gripper from its rest position to the reverse position and from there back to its rest position.
• a compact design for the thread catcher is achieved when the barbs is formed by a provided on its outer side surface incision, which is downstream of the tip of the thread catcher and the thread catcher on its upper side a tip also subordinate groove for receiving the to be separated Has threads that opens into the incision.
• the regions of needle and hook thread to be severed can be received within the groove and separated by cutting edges formed at the outlet of the groove without the aid of a movable counter knife.
• the thread supply-side ends characterized in that they lead from the interface first to the incision and thence along the underside of the thread catcher to the respective thread supply, sufficient to form the initial stitches of the next sewing cycle sufficient length.
• the tip-side end region of the groove is delimited by a bore passing through the thread catcher, the dividing edges of the thread catcher formed thereby can be produced relatively easily and can also be sharpened slightly.
• a vertical mobility limiting stop is provided on the underside of the throat plate in the region of the trajectory of the yarn catcher.
• Fig. 1 A perspective view of a gripper housing a lockstitch sewing machine with a rotating in a horizontal plane gripper and the thread cutting device;
• Fig. 2 An illustration of the thread catcher, the feed dog, the counter knife and the needle plate;
• Fig. 3 A perspective view of the thread cutting device after the penetration of the catcher tip into the needle thread loop widened by the gripper;
• Fig. 4 An illustration corresponding to Figure 3 shortly before the cutting process.
• a lockstitch sewing machine housing 2 is shown, which can be used in a conventional manner in the base plate of a corresponding sewing machine.
• the gripper 1 is arranged on a shaft (not shown) running parallel to the path of movement of the needle, which in turn is driven via a corresponding gear by a stub shaft 4, which is in driving connection with the machine main shaft.
• the gripper 1 works to form lockstitches with a thread-guiding needle 5, which is received by a needle bar, which is also in a corresponding drive connection with the machine main shaft.
• the circulating in a horizontal plane gripper 1 is provided with a hook tip 6 and has in a known manner to a thread supply receiving coil 7, which is secured by means of a between two cams 8 of a housing 2 attached to the throat plate 9 stopping piece 11 against rotational movement.
• a capsule fan 12 is provided in the housing 2 in a conventional manner, the movements of which are also derived from the stub shaft 4.
• the sewing machine has a feed device with a needle and / or an upper transport device. Accordingly, the also driven by a corresponding gear from the stub shaft 4 feed dog 13 is provided in a conventional manner for the passage of the needle 5 with a stitch hole 13.
• the sewing machine also has, in a manner known per se, a stopping device which makes it possible to stop the machine main shaft in certain angular positions.
• the thread cutting device has a thread catcher 14, which is arranged on a parallel to the gripper shaft shaft 15, which also receives its drive via a corresponding gear from the main machine shaft.
• the thread catcher 14 having a substantially "L" shape in plan view is laterally behind the needle 5 in its rest position and is in a horizontal plane from its rest position along a trajectory extending between the stitch hole 13 and the side wall 16 of the gripper 1 Moving reversible position and pivotable from this along the same trajectory back to the rest position feasible.
• a catcher tip 17 is formed on this, which is a barb 18 downstream.
• an incision 21 is formed on the outer side surface 19 of the suture catcher 14, which is arranged downstream of the catcher tip 17.
• the thread catcher 14 On its upper side 22, the thread catcher 14 for receiving the threads to be separated on a catcher tip 17 downstream groove 23, which opens at one end into the recess 21 and the other end in a thread catcher 14 passing through bore 24.
• the end regions of the groove 23 merging into the bore 24 form a semicircular cutting edge 25 of the thread catcher 14.
• a cooperating with the thread catcher 14 stationary arranged counter knife 26 is provided in the immediate area of the stitch pattern, the cutting edge 27 is directed to achieve a pulling cut at an acute angle to the feed direction of the material.
• the counter knife 26 is arranged on the underside of the feed dog 13 of the sewing machine and firmly connected thereto.
• a stop 28 limiting its vertical mobility arranged at the bottom of the throat plate 9 in the region of the trajectory of the yarn catcher 17 .
• the fabric is moved by the feed device in the feed direction by an amount that is less than the stitch length with which the seam is formed.
• the feed dog 10 is positioned such that its tap hole runs centrally to the movement path of the needle 5.
• feed device at least one further stitch (knotting stitch) is formed, which serves to secure the seam against being pulled.
• the needle thread loop is widened by the gripper during the formation of a partial stitch (cutting stitch), after which the thread catcher 14 from a laterally located behind the needle 5 rest position along a between the stitch hole 13 and the side wall 16 of the gripper extending trajectory is moved in a motion reversal position. While the needle and gripper continue to move during the penetration of the suture catcher 14 into the widened needle thread loop, however, since the needle thread loop is caught by the suture catcher 14 and passed therethrough, the initiated stitch can not be properly completed. The formation of this "stitch" thus serves only to allow the penetration of the catcher tip (17) in the expanded needle thread loop and laterally deflect both their leading to the fabric leg and extending from the gripper to the fabric portion of the looper thread.

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

Applications Claiming Priority (2)

Publications (2)

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• 2008
  • 2008-06-24 DE DE102008030620A patent/DE102008030620B3/de not_active Expired - Fee Related
• 2009
  • 2009-06-16 EP EP09768933A patent/EP2300654B1/fr active Active
  • 2009-06-16 WO PCT/EP2009/004353 patent/WO2009156084A1/fr active Application Filing
  • 2009-06-16 AT AT09768933T patent/ATE540151T1/de active

Non-Patent Citations (1)

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