GB1559861A

GB1559861A - Sewing machine having a thred severer

Info

Publication number: GB1559861A
Application number: GB3610376A
Authority: GB
Original assignee: Union Special GmbH
Current assignee: Union Special GmbH
Priority date: 1975-09-02
Filing date: 1976-09-01
Publication date: 1980-01-30
Also published as: IT1071427B; JPS5231153A; DE2538916A1; DE2538916C2; JPS619080B2

Description

(54) A SEWING MACHINE HAVING A THREAD SEVERER (71) We, UNION SPECIAL GMBH (formerly UNION SPECIAL MASCHINENFABRIK GESELLSCHAFT MIT BESCHRANKTER HAF TuNG) a German Company, of 33 Schwabstrasse, 7 Stuttgart 1, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to a sewing machine having a thread severer.

A chain-stitch sewing machine having a thread severer with a thread catcher which is movable between a looper and a workpiece support and which cooperates with a knife and a thread clamp is known from, for example, German Patent Specifications 1,485,424 and 1,685,067. This is a so-called flat bed machine.

In such a machine, the machine bed incorporates a relatively large interior space in which in use, the looper carries out a swinging movement for the purpose of receiving a thread loop. The path of movement of the looper extends below the stitch plate immediately in the region of the path of the needle. When the looper is in one position a space is provided for a thread severer to enter this region.

In another type of sewing machine having support arm acting as a workpiece support, the looper is movable linearly parallel to the support owing to the small amount of space available. There is then generally an absence of free space above the looper for access of the thread catcher when collecting a thread. Furthermore, it is also difficult to fit within a narrow support arm an actuator for a thread catcher such as that illustrated in, for example, German Patent Specification 1 A85,424.

An aim of the present invention is to provide a sewing machine with a threadseverer whose thread catcher, together with knife and thread clamp is when in operation, on the one hand, located outside the looper path and, on the other hand, located at a distance from the stitch-fonning location which ensures that the clamped thread is of satisfactory length for a new seam.

According to the present invention, there is provided a sewing machine having a support arm acting as a workpiece support, a looper arranged to perform a motion combining displacement parallel to an axis which lies at right angles to a workpiece feed direction and lies parallel to the workpiece support and rotation about said axis, and a thread catcher which is movable during a severing operation between the looper and the workpiece support and which cooperates with a knife and a thread clamp, for severing the thread, a guide connected to the thread catcher being arranged to control movement relative to the thread catcher of a carrier carrying the knife and the thread clamp and to guide the thread catcher for movement parallel to said axis of displacement of the looper during the severing operation and away from said axis when moving into an inoperative position, The use of guide members in cooperation with the guide for the thread catcher and the carrier holding the knife and the clamp, renders it possible, in the limited space available in a support arm sewing machine, to impart to the thread catcher a substantially rectilinear movement parallel to the axis of displacement of the looper necessary for collecting the threads and, nevertheless, to bring the thread catcher into an inoperative position at a distance outside the path of the looper which is correct for the required initial length of thread.

In a preferred embodiment, the guide for the thread catcher is in the form of a slide which has angled guideways and which cooperates with guide members secured relative to the machine housing. The guideways may comprise angled slots which are engaged by screw bolts.

The invention is described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a plan view of a portion of a sewing machine bed wherein a thread severer is shown in a withdrawn inoperative position, a workpiece support of the machine being omitted for the sake of clarity; Fig. 2 is a section, taken on the line A-B, through the portion shown in Fig. 1; and Fig. 3 is a further view of the portion illustrated in Fig. 1 with the thread severer shown in an extended operative position.

As illustrated a machine bed 1 merges into an arm-shaped machine portion 2 where in a looper 3 is arranged below a stitching plate 4 which is secured in a workpiece support 5. The looper 3 is movable forwards, i.e. towards the bottom of Fig. 1, as illustrated and backwards, i.e. towards the top of Fig. 1 parallel to an axis which lies perpendicular to a workpiece feed direction and lies parallel to the support 5, being secured to a holder 6 which is carried by a rod 7 movable longitudinally of the portion 2. In addition to effecting longitudinal movements, the rod 7 effects rotary movements about its axis in order to impart to the looper the required movements for evading a machine needle (not illustrated) movable along a path 8: The looper 3 is thus arranged to perform a motion combining displacement parallel to and rotation about the axis of the rod 7.A feed device provided in the machine bed for the purpose of moving the workpiece is not shown.

A thread severer comprises a thread catcher 11, a knife 12, and a thread clamp 13. The thread catcher 11 is connected to a guide in the form of a slide 14. A movable carrier 15 for the knife 12 and the thread clamp 13 cooperates with the slide 14 and guides the thread catcher.

The carrier 15 is urged towards a stop 17 by means of a spring 16 but is normally drawn into an inoperative position by the slide 14 against the force of the spring. For this purpose, the slide 14 is provided with a shoulder 18 which coperates with a projection 19 on the carrier 15.

The slide 14 is mounted on a cover 23 by means of screws 22 which engage within angled guide slots 21 in the slide 14.

Furthermore, the slide 14 has an opening 24 in which the end of a drive lever 25 is located. The drive lever 25 is mounted at 26 and is connected by way of a guide bar 27 to a rod 28 which leads to a drive unit (not illustrated) such as an electro-magnet.

The slide 14 is movable forwards, from an inoperative position, shown in Fig. 1, into an operative position shown in Fig. 3 when the looper 3 is in a foremost extended position. When the looper is in this position, it is possible to extend the thread catcher 11 between the looper and the workpiece support, the thread catcher initially moving laterally of the portion 2 by virtue of the arrangement of the slots 21 and then moving forwardly above the looper 3. into the operative position. The carrier 15 follows this forwards movement of the slide 14 under the action of the spring 16 until it strikes against the stop 17. The carrier 15 is guided in its movement by the engagement of a screw 31 within a slot 30 which is arranged so that the carrier 15 also effects a lateral movement.

The knife 12, clamp 13 and catcher 11 are thus aligned longitudinally of the portion 2 with the catcher 11 positioned to collect the thread from the looper 3. The catcher 11 is now withdrawn bringing the thread against the knife 12 and the clamp 13.

Further rearwards movement of the catcher 11 by withdrawing the slide 14 causes the carrier 15 also to be withdrawn, the thread severer thus returning to its inoperative position.

WHAT WE CLAIM IS: 1. A sewing machine having a support arm acting as a workpiece support, a looper arranged to perform a motion combining displacement parallel to an axis which lies at right angles to a workpiece feed direction and lies parallel to the workpiece support and rotation about said axis, and a thread catcher which is movable during a severing operation between the looper and the workpiece support and which cooperates with a knife and a thread clamp, for severing the thread, a guide connected to the thread catcher being arranged to control movement relative to the thread catcher of a carrier carrying the knife and the thread clamp and to guide the thread catcher for movement parallel to said axis of displacement of

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. may comprise angled slots which are engaged by screw bolts. The invention is described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a plan view of a portion of a sewing machine bed wherein a thread severer is shown in a withdrawn inoperative position, a workpiece support of the machine being omitted for the sake of clarity; Fig. 2 is a section, taken on the line A-B, through the portion shown in Fig. 1; and Fig. 3 is a further view of the portion illustrated in Fig. 1 with the thread severer shown in an extended operative position. As illustrated a machine bed 1 merges into an arm-shaped machine portion 2 where in a looper 3 is arranged below a stitching plate 4 which is secured in a workpiece support 5. The looper 3 is movable forwards, i.e. towards the bottom of Fig. 1, as illustrated and backwards, i.e. towards the top of Fig. 1 parallel to an axis which lies perpendicular to a workpiece feed direction and lies parallel to the support 5, being secured to a holder 6 which is carried by a rod 7 movable longitudinally of the portion 2. In addition to effecting longitudinal movements, the rod 7 effects rotary movements about its axis in order to impart to the looper the required movements for evading a machine needle (not illustrated) movable along a path 8: The looper 3 is thus arranged to perform a motion combining displacement parallel to and rotation about the axis of the rod 7.A feed device provided in the machine bed for the purpose of moving the workpiece is not shown. A thread severer comprises a thread catcher 11, a knife 12, and a thread clamp 13. The thread catcher 11 is connected to a guide in the form of a slide 14. A movable carrier 15 for the knife 12 and the thread clamp 13 cooperates with the slide 14 and guides the thread catcher. The carrier 15 is urged towards a stop 17 by means of a spring 16 but is normally drawn into an inoperative position by the slide 14 against the force of the spring. For this purpose, the slide 14 is provided with a shoulder 18 which coperates with a projection 19 on the carrier 15. The slide 14 is mounted on a cover 23 by means of screws 22 which engage within angled guide slots 21 in the slide 14. Furthermore, the slide 14 has an opening 24 in which the end of a drive lever 25 is located. The drive lever 25 is mounted at 26 and is connected by way of a guide bar 27 to a rod 28 which leads to a drive unit (not illustrated) such as an electro-magnet. The slide 14 is movable forwards, from an inoperative position, shown in Fig. 1, into an operative position shown in Fig. 3 when the looper 3 is in a foremost extended position. When the looper is in this position, it is possible to extend the thread catcher 11 between the looper and the workpiece support, the thread catcher initially moving laterally of the portion 2 by virtue of the arrangement of the slots 21 and then moving forwardly above the looper 3. into the operative position. The carrier 15 follows this forwards movement of the slide 14 under the action of the spring 16 until it strikes against the stop 17. The carrier 15 is guided in its movement by the engagement of a screw 31 within a slot 30 which is arranged so that the carrier 15 also effects a lateral movement. The knife 12, clamp 13 and catcher 11 are thus aligned longitudinally of the portion 2 with the catcher 11 positioned to collect the thread from the looper 3. The catcher 11 is now withdrawn bringing the thread against the knife 12 and the clamp 13. Further rearwards movement of the catcher 11 by withdrawing the slide 14 causes the carrier 15 also to be withdrawn, the thread severer thus returning to its inoperative position. WHAT WE CLAIM IS:

1. A sewing machine having a support arm acting as a workpiece support, a looper arranged to perform a motion combining displacement parallel to an axis which lies at right angles to a workpiece feed direction and lies parallel to the workpiece support and rotation about said axis, and a thread catcher which is movable during a severing operation between the looper and the workpiece support and which cooperates with a knife and a thread clamp, for severing the thread, a guide connected to the thread catcher being arranged to control movement relative to the thread catcher of a carrier carrying the knife and the thread clamp and to guide the thread catcher for movement parallel to said axis of displacement of

the looper during the severing operation and away from said axis when moving into an inoperative position.

2. A machine as claimed in Claim 1, wherein the guide member is in the form of a slide which has angled guideways arranged to cooperate with guide members for guiding the movement of the thread catcher.

3. A machine as claimed in Claim 2, in which the guideways comprise angled slots and the guide members comprise bolts engaged within the slots.

4. A sewing machine constructed and arranged substantially as herein particularly described with reference to and as illustrated in the accompanying drawings.