Cam for sewing machines, in particular for buttonhole machines

Abstract

 A cam for sewing machines, in particular for chainstitch buttonhole sewing machines, intended to control the transverse motion of the bed and comprising a cam holder carrying at least three cam disks (1,2,3), with a part of the cam path of the bed transverse motion provided on the periphery of each of them. The angular positions of at least two of said cam disks (2,3) are adjustable.

Description

Field of the invention

[0001] The invention relates to a cam for sewing machines, in particular for chainstitch buttonhole sewing machines, intended to control the transverse motion of the bed and comprising a cam holder.

Background art

[0002] The transverse motion of the bed of a buttonhole sewing machine is presently controlled by interchangeable cams with various rigidly predetermined path shapes, the control cam actually in use being mounted on a cam holder while the other cams are stored outside the machine. To change the parameters of the buttonhole to be sewn, the control cam is replaced by the adequate one from those stored. As a rule, each buttonhole sewing machine is supplied with a set of sixteen interchangeable cams for basic shapes and sizes of buttonholes.

[0003] In another well-known solution, the interchangeable cams are replaced by interchangeable disks which are not so complicated in the production and therefore cheaper.

[0004] The drawback of the two above mentioned solutions consists in a considerably high number of interchangeable cams or disks needed with the correspondingly high requirements placed upon the production and storage of interchangeable cams or disks, on the time-consuming and in technical respect exacting adjustment of the machines in current factory use, and especially in the impossibility of setting the buttonhole parameters, in particular the lengths of the buttonhole, to other values than predetermined by the set of interchangeable cams or disks available.

Principle of the invention

[0005] The above drawbacks of the background art have been eliminated by the cam for sewing machines according to the invention whose principle consists in that the cam holder carries at least three cam disks, with a part of the cam path of the bed transverse motion provided on the periphery of each of them, and that the angular positions of at least two of said cam disks are adjustable.

[0006] In addition to permitting to dispense with the large number of cams or disks and with carrying out the exchange operations, the chief advantage of the invention consists in the possibility of stepless adjustment of the sizes (lengths) of the buttonhole to be sewn.

[0007] In one variant of the solution, each of the disk cam whose angular position is adjustable is coupled with adjustment means of its own.

[0008] The adjustment procedure is simplified if the adjustment means is common to the adjustable disk cams. Unless stated otherwise, the term

adjustable cam disk" as hereinafter used is intended to mean

cam disk with adjustable angular position".

[0009] Preferably, the adjustable cam disks are at least on a part of their inner periphery fitted with an inner gearing, each adjustable cam disk meshing with a gear wheel related thereto. Besides, the gear wheels mesh with each other and one of them is coupled with an adjustment means. In case of two cam disks, this arrangement provides for the opposite sense of rotation of the cam disks.

[0010] The adjustable cam disks are seated on one side of a non-adjustable cam disk which simplifies the cam design and permits to make the non-adjustable cam disk of full material.

[0011] To increase the range of sewn buttonholes, the non-adjustable cam disk is fitted with an interchangeable segment having provided thereon at least a part of the cam path of the non-adjustable cam disk used for stitching the buttonhole eye.

[0012] A further increase in the length range of sewn buttonholes can be achieved by inserting between the non-adjustable cam disk and its adjoining adjustable cam disk at least one rotatably mounted auxiliary overlapping disk coupled with the non-adjustable cam disk and coupled in motion with one of the adjustable cam disks.

[0013] To achieve a simple and reliable in function coupling of the auxiliary overlapping disk with the non-adjustable cam disk and with the adjustable cam disk, the auxiliary overlapping disk is fitted with two grooves into the second of which there is inserted a limiting pin fixed in the non-adjustable cam disk while into the first of them there is introduced a drive pin fixed in one of the adjustable cam disks.

Description of drawings

[0014] Examples of embodiment of the cam for sewing machines according to the invention are schematically shown in Figs. 1 to 5 of the accompanying drawings in which show Fig. 1 view on the cam in exploded state, Fig. 2 view on the cam with auxiliary overlapping disk in exploded state, Fig. 3a axonometric view on the cam shown in Fig. 2, Fig 3b view from below on the cam shown in Fig. 2, Fig. 4a axonometric view on the cam shown in Fig. 1, Fig. 4b view on the interchangeable segments and Fig. 5 axonometric view on the cam shown in Fig. 1 in partial section.

Specific description

[0015] The cam for sewing machines, in particular for chainstitch buttonhole sewing machines, is in a well-known manner coupled with the bed of the sewing machine and serves to control the bed transverse path. The cam comprises a non-adjustable cam disk 1 with a part of the cam path 11 provided on its periphery. A part of the non-adjustable cam disk 1 is made as a cylindrical support 12 having provided therein recesses 13, 14 for gear wheels. A part of the cam path 11 of the non-adjustable cam disk 1 is made on an interchangeable segment 15 which is fixed to the non-adjustable cam disk 1. The cam path 11 on the interchangeable segment 15 serves to produce the buttonhole eye.

[0016] In the embodiment shown in Fig. 1, 4a, 5 the cylindrical support 12 and the ring-shaped section 16 of the non-adjustable cam disk 1 carry respectively a first adjustable cam disk 2 and a second adjustable cam disk 3 fitted with the parts 21, 31 of the cam path on their outer peripheries and with inner gearings 22, 32 on a part of their inner peripheries. Gear wheels 4, 5 are rotatably mounted in the recesses 13, 14 of the cylindrical support 12 of the non-adjustable cam disk 1, and each of them meshes with the inner gearing of one of the adjustable cam disks 2, 3. At the same time, the gear wheels 4, 5 mesh with each other.

[0017] The second adjustable cam disk 3 is overlapped from above by an overlapping plate 6 fixed to the front of the cylindrical support 12. One of the gear wheels 4, 5 is coupled with a turning means 7 shaped in the illustrated embodiment as a cylinder.

[0018] In a not illustrated example of embodiment, the gear wheels 4, 5 are seated separately from each other, and each of them meshes with an inner gearing of each of the adjustable cam disks 2, 3. Each of the gear wheels 4, 5 meshes with a turning means 7 of its own.

[0019] In the embodiment shown in Fig. 2, 3a, 3b an auxiliary overlapping disk 8 is inserted and on the cylindrical support 12 of the non-adjustable cam disk 1 rotatably mounted between the ring-shaped periphery 16 of the non-adjustable cam disk 1 and its adjoining first adjustable cam disk 2. The auxiliary overlapping disk 8 is equipped with two grooves 81, 82 into the first one 81 of which there is inserted a drive pin 23 fixed in the first adjustable cam disk 2 and into the second one 82 of which there is inserted a limiting pin 17 fixed in the ring-shaped section 16 of the non-adjustable cam disk 1. A part of the cam path 83 is provided on the periphery of the auxiliary overlapping disk 8.

[0020] If the buttonhole length is to be changed, the operator turns the turning means. This motion is transmitted, firstly, to the gear wheel 4 and then to the first adjustable cam disk 2, and, secondly, to the second gear wheel 5 and then to the second adjustable cam disk 3 which thus receives a turning motion in a sense opposite to that of the first adjustable cam disk 2. The change in the mutual position of the cam paths of the non-adjustable cam disk 1 and of the two adjustable cam disks 2, 3 results in the modification of the buttonhole length.

[0021] If the shape of the buttonhole eye is to be changed, the operator exchanges the interchangeable segment 15 situated on the non-adjustable cam disk 1.

[0022] In the embodiment shown in Fig. 2, 3a, 3b the rotation of the adjustable cam disk 2 moves the drive pin 23 in the first groove 81, reaches the end of the groove 81 and then begins to move the auxiliary overlapping disk 8. Simultaneously, the second groove 82 moves in relation to the limiting pin 17 which thus reaches the end of the second groove 82 and also of the adjustable cam disks 2, 3. A subsequent motion is possible only in the reverse direction. The turning movement in one direction increases the buttonhole length, and reduces it in the reverse direction.

[0023] Other embodiments can use a greater number of adjustable cam disks and/or of auxiliary overlapping disks, each of the auxiliary overlapping disks being coupled with the non-adjustable cam disk and coupled in motion with one of the adjustable cam disks.

Claims

1. A cam for sewing machines, in particular for chainstitch buttonhole sewing machines, intended to control the transverse motion of the bed and comprising a cam holder, characterized by that the cam holder carries at least three cam disks (1,2,3), with a part of the cam path of the bed transverse motion provided on the periphery of each of them, and that the angular positions of at least two of said cam disks (2,3) are adjustable.

2. A cam as claimed in Claim 1, characterized by that each of the cam discs (2,3) whose angular positions are adjustable is coupled with an adjusting means (7).

3. A cam as claimed in Claim 2, characterized by that each cam disk is coupled with an adjusting means (7) of its own.

4. A cam as claimed in Claim 2, characterized by that the cam discs (2,3) whose angular positions are adjustable, have one adjusting means (7) in common.

5. A cam as claimed in Claim 4, characterized by that that the cam discs (2,3) whose angular positions are adjustable are at least at a part of their inner periphery equipped with an inner gearing (22, 32), that each of the cam discs (2,3) whose angular positions are adjustable meshes with a gear wheel (4, 5) related thereto, that the gear wheels (4, 5) mesh with each other and that one of them is coupled with the adjusting means (7).

6. A cam as claimed in one of Claims 1 to 5, characterized by that the cam disks (2,3) whose angular positions are adjustable are mounted on the cam disk (1) whose angular position is not adjustable, and more specifically, on one of its sides.

7. A cam as claimed in one of Claims 1 to 6, characterized by that the cam disk (1) whose angular position is not adjustable is fitted with an interchangeable segment (15) having provided thereon at least a part of the cam path of the the cam disk (1) whose angular position is not adjustable serving for the production (stitching) of the buttonhole eye.

8. A cam as claimed in one of Claims 1 to 7, characterized by that between the cam disk (1) whose angular position is not adjustable and its adjoining cam disk (2) whose angular position is adjustable there is inserted at least one auxiliary overlapping disk (8) whose angular position is changeable and that is coupled both with the cam disk (1) whose angular position is not adjustable, and with one (2) of the cam disks whose angular position is adjustable.

9. A cam as claimed in Claim 8, characterized by that the auxiliary overlapping disk (8) is equipped with two grooves (81, 82) and that in the second groove (82) there is inserted a limiting pin (17) fixed in the cam disk (1) whose angular position is not adjustable and that in the first groove (81) there is inserted a drive pin (23) fixed in one of the cam disks (2) whose angular position is adjustable.

Drawing