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(11) | EP 0 028 210 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | An improved cutting device of cloth fringes on an overlock-type sewing machine |
| (57) In darn sewing of a cloth fringe on a overlock-type sewing machine, the surplus fringe
section is cut by a heat cutter (12) and removed off the sewing station via an accompanying
pneumatic suction pipe (11) for a simplified construction. |
Background of the invention
[0001] The present invention relates to an improved cutting device of cloth fringes on an overlock-type sewing machine, and more particularly relates to an improved device for beautifully cutting and removing surplus fringe section of a cloth made of synthetic fibers during sewing operation on a machine suited for darn sewing of such cloth fringes, i.e. on a so-called loverlock-type sewing machine.'
[0002] For darn sewing of a cloth on an overlock-type sewing machine, the surplus fringe section of the cloth has to be cut and removed prior to operation by a sewing needle. For this purpose, the sewing machine has to be provided with a cutting device of cloth fringes. Conventionally, such a cutting device is generally provided with a pair of cutting blades, one being swingable and the other stationary.
[0003] Use of such cooperating cutting blades is inevitably accompanied with the following drawbacks.
(1) Movement of the swingable cutting blade is derived from the main drive shaft of the sewing machine and this driving mechanism requires a complicated construction. Further, cooperation of the pair of cutting blades causes early abration of the blades. When the cloth to be cut is made of synthetic fibers, in particular polyester fibers, the blades have to be replaced once in one to two months. Such frequent replacement requires increased manual labour and high technique.
(2) The cut edge of the fringe tends to fray, the superimposed upper and lower fringe tend to separate from each other, and the relatively wide sewn fringe tends to cause discomfort in use of the cloth.
(3) After repeated use, dull edges of the cutting blades tend to cause faulty sewing. Further, any additional element has to be provided in order to remove the cut surplus fringe section off the sewing station.
Summary of the invention
[0004] It is one object of the present invention to provide a cutting device for an overlock-type sewing machine which requires reduced replacement of its operational elements.
[0005] It is another object of the present invention to provide a cutting device for an overlock-type sewing machine which provides fortified sew lines with reduced faults in sewing operation.
[0006] In accordance with the present invention, a heat cutter in the form of a wire is arranged in the travelling course of a cloth fringe on the upstream side of a sewing needle for cutting of the surplus fringe section and accompanied with a pneumatic suction mouth for removal of the cut surplus fringe section.
Description of the drawings
[0007]
Fig. 1 is a perspective view of the conventional cutting device and its related parts on an overlock-type sewing machine,
Fig. 2 is a perspective view of an overlock-type sewing machine provided with the cutting device in accordance with the present invention,
Fig. 3 is a plan view of the cutting device shown in Fig. 2, and
Figs. 4 and 5 are side and front views of the cutting device shown in Fig. 2.
Description of the preferred embodiment.
[0008] One typical example of the sewing station on the conventional overlock-type sewing machine is shown in Fig. 1. The station is provided on a horizontal needle plate C and a cloth forwarding element D arranged on the needle plate C. A-sewing needle A is arranged over the needle plate C for vertical reciprocation. A swingable arm B is arranged near the sewing needle A and operable connected to the main drive shaft (not shown) of the machine for a prescribed swing motion. An upper movable cutter blade K is integrally mounted to the free end of the arm B and a lower stationary cutter blade K' is secured sideways to the needle plate.C for cutting of cloth fringes in cooperation with the movable cutter blade K.
[0009] As already described in detail, this conventional arrangement of the cutting device for an overlock-type sewing machine is accompanied with various drawbacks.
[0010] One embodiment of the cutting device in accordance with the present invention is attacked to an overlock-type sewing machine as shown in Fig. 2, in which the sewing machine is as usual provided, in addition to the above-described elements A, C and D, a cloth pressor E arranged over the cloth forwarding element D, a yarn tension controller F and sewing yarns Y delivered from their supply bobbins. These elements are all mounted on a pedestal G of the machine.
[0011] The cutting device of the present invention is generally indicated with a reference numeral 10. The cutting device 10 includes a substantially vertically arranged suction pipe 11 which is connected to a given pneumatic suction source (not shown) and has a bent top section lla with an open suction mouth llb directed to the sewing station of the machine. The suction mouth llb is spanned by a heat cutter 12 made of a nickel-chrome wire. The suction pipe 11 is adjustably mounted to the pedestal G of the machine by a proper fastener 13.
[0012] The construction of the cutting device 10 is shown in more detail in Figs. 3 through 5. The free end of the bent top section lla is chamfered by a vertical plane with respect to its axis in order to provide the suction mouth llb and the heat cutter 12 is arranged vertically across the suction mouth llb as close to the needle plate C as possible. The side of the free end of the bent top section lla facing a stitch tongue H is closed.
[0013] In connection with the above-described arrangement, it is important that the heat cutter 12 is located on the upstream side of the sewing needle A along the travelling course of the_cloth fringe to be sewn and the suction mouth llb of the suction pipe 11 opens facing the upstream side of the heat cutter 12 as clearly shown in Fig. 3.
[0014] In operation, as the cloth fringe approaches the sewing station, the surplus section of the cloth fringe is continuously separated by contact with the heat cutter 12 . from the remaining section of the cloth fringe to be sewn by the sewing needle A, and the separated section of the cloth fringe is sucked into the suction mouth llb for removal off the station via the suction pipe 11.
[0015] The cutting device of the present invention employs a cutting element, i.e. the heat cutter 12, which requires no replacement of sharpening. Cutting of the cloth fringe by heating causes fusion of the component fibers which well prevents unfavourable displacement between the superimposed cloth fringes and forms a fortified sew line. Close arrangement of the heat cutter to the needle plate allows high tension of the sewing yarn and smaller dimension of the stitch tongue, which assures formation of a further fortified sew line and beautiful appearance of the sewn fringe. The stationary arrangement of the cutting elements, i.e. the heat cutter, results in a remarkably simplified construction when compared with the conventional one employing the movable cutter blade. Further, the arrangement of the suction mouth on the upstream side of the sewing needle reliably prevents reach of the separated surplus fringe section to the sewing point, which otherwise would seriously disturb normal sewing operation.
a heat cutter arranged in the travelling course of a cloth fringe to be sewn on the close upstream side of a sewing needle of said machine across a plane including said cloth fringe, and
a pneumatic suction mouth opening in the close proximity of said heat cutter.