JPS644479B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thread cutting device with thread retention, in particular a thread cutting device adapted to be attached to the casing or some other part of a sewing machine.

a disc adapted to be attached to a fabric presser bar of a sewing machine and having a circular cutting edge; and a frusto-conical member coaxially mounted on a screw that fixes the fabric presser leg to the fabric presser bar of the sewing machine. A thread cutting device is disclosed in particular in French Patent No. 1 158 669, in which the conical member is pressed against the cutting disk by means of a spring.

This known device has the disadvantage that it can only hold the thread sufficiently close to the axis of the screw, and there is a risk of injury due to contact with the circular cutting edge of the disc, which is usually not sufficiently protected. ing.

In order to eliminate this disadvantage, the device according to the invention comprises a mandrel with a head having a substantially circular cutting edge on the side facing the mandrel, and a first slider member fitted on the mandrel. , a second slider member provided on the first slider member, each of the slider members abutting the head of the mandrel on either side of a substantially circular cutting edge, the substantially circular cutting edge being disposed on the first slider member. It is characterized by projecting into a substantially annular chamber defined by the outer surface of the member and the inner surface of the second slider member.

Embodiments of the device according to the invention will be further described with reference to the accompanying drawings.

As shown in FIG. 1, the present thread cutting device includes a mandrel 1 having a thread 2 at one end and a head 3 having a knurled outer periphery 4 at the other end. On the surface of the head 3 facing the lower side of the head, i.e. towards the axle 1, a groove is formed at the intersection of the outer periphery 7 of the circular groove 8 provided in this surface and the frusto-conical part 6 of the head. A circular cutting edge 5 is provided.
A first slider member 9 is fitted to the mandrel 1,
The end of the slider member adjacent the head 3 has a frusto-conical portion spaced from the head 3 and shaped to fit into a groove 8 formed in the head 3 adjacent the inner periphery of the head. It has 10. Nevertheless, this truncated conical part 1
0 remains at a distance from the outer periphery 7 of the groove 8 and also from the circular cutting edge.

When the mandrel 1 is screwed deeply into a support, such as the leg or rod of a fabric holder of a sewing machine, the slide member 9 is pressed against the bottom of the groove 8 of the head 3. A second slider member 12 is fitted onto the slider member 9 so as to be coaxial with the mandrel 1, and the end of the slider facing the head 3 abuts against the frustoconical portion 6 of the head 3 and is connected to the spring 14. Therefore, it is pressed against the relevant part.

In a sewing machine, for example, if one wishes to cut a thread at the end of a sewing process, the user can pull a section of the thread and move this tensioned section transversely to the axis of the mandrel 1 to cut the thread. 3 and the end 13 of the slider member 12. Thus, this tensioned thread is forced against the action of the spring 14 on the slider member 12.
is displaced to take a position between the frusto-conical part 10 and the circular cutting edge 5, and the circular cutting edge 5 cuts the thread. The user then pulls the part of the thread that is attached to the sewn fabric while the other part of the thread is attached to the frusto-conical part 6.
and the end 13 of the slider member 12.

The slider member 9 is placed in the groove 8 in order to remove any remaining thread strands that are taken into the annular chamber defined by the outer surface of the first slider member 9 and the inner surface of the second slider member 12. It is attached to the mandrel 1 with an axial play between the bottom and a retaining ring 15 provided for holding the slider member 9 on the mandrel 1. Similarly, the slider member 12 is attached to the slider member 9 with axial play.

This axial play of the slider member 12 on the slider member 9 is achieved by providing the slider member 12 with an inner circular rib 18 which, against the action of the spring 14, It can be moved on the cylindrical part 19 of the first slider member 9 before the frustoconical part 10 of the gap. The ribs 18 form a partition that prevents threads or lint from entering the chamber 20 for the spring 14.

In the embodiment shown in FIG. 2, a nut 16 is provided for adjusting the tension of the spring 14. Mandrel 1
The end of the slide member 9 opposite to the end abutting the head 3 has a thread 17 into which a nut 16 can be screwed against the action of the spring 14. Preferably, the nut 16 has six flats and is adapted to be screwed onto the slider member 9 by rotating the slider 12 about its axis. Slider member 12
A portion of the inner surface of the nut 16 has a shape that corresponds to the six flat surfaces of the nut 16 depending on its height. Since the slider member 12 can be disassembled,
An axial play is provided in the slider member 9 in order to allow removal of the strand of thread that remains trapped in the annular chamber defined by the outer surface of the slider member 9 and the inner surface of the slider member 12. There is no longer a need to provide one.

In the embodiment shown in FIG. 4, the face of the head 3 facing towards the mandrel 1 has a circular cutting edge 5, which cuts the circumferential edge of the head 3 facing towards the mandrel 1. Trough-shaped circular groove 2 provided in the conical head extension 6
1 and the outer circumferential edge 7 of a circular groove 8 provided in the face of the head 3 facing towards the axle 1. First slider member 9
is fitted in the mandrel 1, the end of the slider member facing towards the head 3 forming a gap and having a truncated head shaped to fit into a groove 8 formed in the head 3. It has a conical portion 10. This conical portion is remote from the outer periphery 7 of the groove 8 and from the cutting edge 5. The first slider member 9 is held in position by a ring 15 fitted in a circumferential groove in the mandrel 1.

The second slider member 12 is fitted into the slider member 9 coaxially with the mandrel 1, and the end of the slider member facing towards the head 3 has a trough-shaped circular groove 2.
1 and is pressed against the bottom by a spring 14.

Slider portion 1 in contact with the bottom of the gutter-shaped circular groove 21
It is desirable that the edges of the ends of the grooves 2 and 2 are chamfered to improve contact with the grooves 21. More preferably, the chamfering of the edge of this end face of the slider member 12 corresponds to the curved surface of the bottom of the groove 21.

In this way, the thread introduced into the device between the head 3 and the second slider member 12 is connected to the bottom of the groove 21 of the head 3 and the chamfered abutment end 13 of the slider 12. When held between them and pulled, the thread slides in the direction of the groove 8 over the frustoconical part 10 of the throat of the slider member 9. As a result, the thread passes over the cutting blade 5 under force, and the cutting blade 5 cuts the thread here. Part of the thread is pulled out of the device,
The remaining portion is held between the groove 21 of the head 3 and the abutment end 13 of the slider 12.

As is clear from the figure, the circular groove 21 makes it particularly easy for the thread to break at the cutting edge 5, and the contact between the bottom of the circular groove 21 and the chamfered edge of the end 13 of the slider 12 makes it easy to cut the thread at any time. The cut thread is held securely.

[Brief explanation of drawings]

FIG. 1 is an axial sectional view, FIG. 2 is an axial sectional view of the first variant, FIG. 3 is a front view of the end of the first variant, and FIG. 4 is an axial sectional view of the second variant. It is a diagram. 1... Mandrel, 3... Head, 5... Cutting blade, 9...
...first slider member, 12...second slider member.

Claims (1)

Claims: 1. A mandrel 1 with a head 3 having a substantially circular cutting edge 5 on the face facing the mandrel 1;
It consists of a first slider member 9 fitted into the first slider member 9 and a second slider member 12 provided on the first slider member 9, both slider members respectively touching the head of the mandrel 1 on either side of the substantially circular cutting edge 5. 3 and that the substantially circular cutting edge 5 projects into a substantially annular chamber defined by the outer surface of the first slider member 9 and the inner surface of the second slider member 12. A thread cutting device with characteristic thread retention. 2 A head 3 in which the cutting edge 5 is inclined in the direction of the mandrel 1
periphery 6 of the head 3 facing towards the mandrel 1
The device according to claim 1, characterized in that the circular groove (8) is formed at the intersection with the outer circumferential edge (7) of the circular groove (8) provided on the surface. 3. The end of the first slider member 9 which abuts the head 3 of the mandrel 1 is shaped so as to constitute a bottom part which allows it to enter into the groove 8 along the inner peripheral edge 11 of the groove 8; 3. Device according to claim 1, characterized in that said end of the groove is spaced apart from the outer periphery of the groove. 4 The end of the first slider member 9 is a truncated conical portion 1
0, and the thread introduced into the chamber defined by the outer surface of the first slider member 9 and the inner surface of the second slider member 12 passes over the frustoconical part 10 of the slider 9. Device according to claims 1 to 3, characterized in that it is adapted to slide and pass over the cutting blade (5). 5 The end of the second slider member 12 rests against the inclined peripheral edge 6 of the head 3 of the axle and with the outer peripheral edge 7 of the circular groove 8 provided in the face of the head 3 facing towards the axle 1. At a point beyond the cutting edge 5 formed at the intersection with the peripheral edge 6, the spring 1
4 against said circumferential edge 6 and which, in use, is introduced between the inclined circumferential edge 6 of the head 3 of the mandrel 1 and the abutment surface 13 of the second slider member 12 against said circumferential edge 6. is held in that position, while the other part of the thread passes over the cutting blade 5 and is cut, leaving the outer surface of the first slider member 9 and the inner surface of the second slider member 12 5. Device according to claim 1, characterized in that it is withdrawn from the device through a chamber thus constituted. 6. The free end of the mandrel 1 is provided with a thread, which thread portion cooperates with a thread formed on the support member, such that the free end of the first slider member abuts the support member during use. An apparatus according to claims 1 to 5, characterized in that: 7. The device according to claims 1 to 6, wherein the support member is a fabric presser bar of a sewing machine, and the device is for ensuring that the fabric presser foot is securely fixed to the bar. . 8. Claims 1 to 5, characterized in that the first slider member 9 is attached to the mandrel 1 with axial play between the bottom of the circular groove 8 and the retaining ring 15. The device described above. 9 In order to ensure a constant axial play with respect to the second slider member 12 and to prevent threads or lint from entering the chamber 20 of the spring 14, the second slider member 12 is connected to the first In front of the frustoconical part 10 of the cylindrical interlocking part 19 of the slider member 9, a circular inner rib 18 is placed in contact with the interlocking part 19.
An apparatus according to any one of claims 1 to 5, characterized in that it has: 10 The cutting edge 5 connects the inner edge of the trough-shaped circular groove 21 in the frustoconical extension 6 of the peripheral edge of the head 3 facing towards the mandrel 1 and the head facing towards the mandrel 1. 3. The device according to claim 1, wherein the circular groove 8 is formed at the intersection with the outer circumferential edge 7 of the circular groove 8 provided on the surface of the holder. 11. The device according to claim 10, characterized in that the second slider member 12 is brought into contact with the bottom of the trough-shaped circular groove 21 by the action of a spring 14. 12. The device according to claim 11, characterized in that the edge of the end of the slider member 12 that contacts the bottom of the trough-shaped circular groove 21 is chamfered. 13. The device according to claim 12, characterized in that the chamfering of the edge of the end of the slider member 12 that contacts the bottom of the trough-shaped circular groove 21 corresponds to the curved surface of the bottom of the groove.