Messer

Abstract

Knife (4), in particular upper knife, for a sewing or overlocking machine (1), wherein the knife has a direction of movement (Z) and a cutting edge (41) whose edge preferably runs at an angle (α) to the direction of movement (Z), characterized in that the cutting edge (41) is toothed.

Description

[0001] The invention relates to a knife, in particular an upper knife, for a sewing or overlocking machine according to the preamble of claim 1. Furthermore, the invention relates to a sewing or overlocking machine with such a knife.

[0002] In some sewing machines, such as overlock or serger machines, the material being worked, for example fabric, is cut simultaneously when a seam is created. Such machines typically require two blades: an upper blade and a lower blade. The upper blade is usually movable, while the lower blade is stationary. The upper blade moves up and down in one direction, cutting the fabric, which is sheared between the upper blade and the lower blade (or counter blade). Such a machine is known, for example, from DE 11 2018 001 564 B4.

[0003] Typically, the cutting edges of sewing machines are angled relative to the fabric feed direction, i.e., the sewing direction. This means the cutting edge is not parallel to the needle plate of the sewing machine and parallel to the sewing direction. As a result, the fabric is sometimes pressed against the sewing direction during the sewing process. This effect usually worsens as the cutting edge wears down, even with heavy fabrics. In such a case, the needle, which passes through the fabric or material being sewn during the cutting process, can break.

[0004] The object of the present invention is therefore to create a knife of the type mentioned above with which the disadvantages described above can be avoided, particularly in sewing machines or overlock machines suitable for household use. It is also intended to create a sewing machine or overlock machine suitable for household use with which these disadvantages can be avoided.

[0005] This problem is solved by a knife with the features of claim 1 and a sewing or overlocking machine with the features of claim 5. Advantageous embodiments are found in the respective dependent claims.

[0006] According to the invention, a knife, in particular an upper knife, for a sewing or overlocking machine is proposed, which has a direction of movement and a cutting edge that is toothed according to the invention. The edge of the cutting edge preferably runs at an angle to the direction of movement. In principle, the angle can be any desired degree. Preferably, it is an acute angle, i.e., an angle greater than 0° and less than 45°; other angles are of course also conceivable.

[0007] The serrated cutting edge ensures that the material being processed, whether it be a fabric such as a woven or non-woven material, or another flexible sheet material, is held firmly by the blade during cutting and not shifted against the sewing direction. This is particularly effective when there is an angle between the cutting edge and the sewing direction, as it suppresses the tendency of the material to be pushed back against the sewing direction.

[0008] The serration of the cutting edge can be achieved in various ways. According to a preferred embodiment, the cutting edge has serrations formed by parallel, preferably V-shaped, grooves across its width. Such V-shaped grooves or furrows can, for example, be machined into a smooth cutting edge using an abrasive. Preferably, these grooves or furrows extend parallel to each other across the entire width or a substantial portion of the cutting edge.

[0009] Different knife types are also conceivable with the cutting edge according to the invention. A preferred embodiment provides that the knife is designed as a hook knife, with the cutting edge then arranged on a head section of the knife. Preferably, the knife has a coupling section opposite a head section in the direction of movement (Z) for mechanical coupling with the knife drive of a sewing machine or overlock machine. The coupling section can, for example, have an opening through which a coupling element such as a screw or the like can be passed.

[0010] The invention further relates to a sewing or overlocking machine with a stitch plate for supporting a material to be sewn or overlocked, in particular a fabric, at least one feed dog arranged in the area of ​​the stitch plate for advancing the material to be processed in a sewing direction, at least one sewing needle, a presser foot for pressing the material to be processed against the stitch plate and / or the feed dog, and a knife movable in one direction of movement for cutting the material to be processed during the sewing or overlocking process. The knife is a movable knife designed as described above.

[0011] In the simplest case, the direction of movement can be perpendicular to the sewing direction. Of course, configurations are also conceivable in which the angle between the knife's direction of movement and the sewing direction is not 90°.

[0012] Preferably, a stationary counter-blade is arranged within the effective range of the movable blade. Effective range means that the cutting edge of the movable blade, during the execution of the movement in the direction of movement, passes by the cutting edge of the counter-blade at least temporarily and at least partially.

[0013] The invention is described below with reference to the Fig. 1-4 explained in more detail. Fig. Figure 1 shows a perspective view of a sewing or overlocking machine according to the present invention. Fig. Figure 2 shows a perspective view of the front of a movable knife according to the invention, Fig. 3 - shows a close-up of detail A from Fig. 2, Fig. Figure 4 shows a top view of the back of a movable knife according to the invention.

[0014] The in Fig. The sewing or overlocking machine 1 shown in Figure 1 (hereinafter referred to as "machine") has a stitch plate 2 in which at least one feed dog 3 is arranged and provides for the advancement of a material or fabric (not shown) in a sewing direction X. The material to be processed is pressed against the stitch plate 2 or the feed dog 3 by means of a presser foot 9. In the example shown, two sewing needles 5, 6 are present, through which threads 7, 8 are guided to produce the overlock seam. Furthermore, a movable upper knife 4 is provided, which preferably has a cutting edge at its head 42 and can be moved back and forth in the direction of movement Z to cut the material to be processed during the sewing process. The movable knife 4 interacts with a counter knife or lower knife, which is not shown in this illustration but is preferably fixedly connected to the machine 1.

[0015] The movable knife according to the invention is more precisely in the Fig. 2-4 shown.

[0016] First, this knife preferably comprises a head section 42 on which a cutting edge 41 is arranged. Furthermore, the knife 4 has a coupling section 43 with which the movable knife can be coupled to a corresponding coupling mechanism of the machine 1. For this purpose, for example, an opening 44 on the coupling section 43 can be used, through which a coupling element such as a bolt, pin, or screw can be passed. The coupling mechanism then enables the knife 4 to move back and forth in the direction of movement Z.

[0017] According to the invention, the cutting edge 41 of the knife 4 is designed in a special way, as can be seen in particular in the detailed view of detail A in the Fig. 3 can be extracted.

[0018] It can be seen that the knife 4 has teeth 46 on its cutting edge 41. The edge 47 of the cutting edge is therefore toothed. Preferably, the teeth are formed such that corresponding indentations, grooves, or furrows are introduced into a smooth cutting edge using a grinding tool; these preferably have a V-shape in cross-section. Of course, other geometries are also conceivable. It can be seen that the direction of the edge 47 of the cutting edge 41 has an angle to the sewing direction X. This is visible in the rear view of Fig. Figure 4 shows this in more detail. There, it can be seen that the angle β between the edge of the cutting edge 41 and the sewing direction X is preferably an acute angle, which is therefore less than 45°. Accordingly, the angle between the sewing direction X and the direction of movement Z of the knife is α = 90° - β, provided that the sewing direction X and the direction of movement Z are perpendicular to each other. The counter-knife or lower knife, which is not shown, can have a preferably oppositely inclined cutting edge. It is preferably provided that the edge 47 of the cutting edge 41 has a bevel such that it aligns with the sewing direction X of the stitch plate 2 (compare Figure 4). Fig. 1) approximates.

[0019] The toothing 46 ensures that a material to be processed, such as a fabric, is not pushed against the sewing direction X during sewing and cutting, but is prevented from doing so by the toothed movable knife 4. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 11 2018 001 564 B4

[0002]

Claims

[1] Knife (4), in particular upper knife, for a sewing or overlocking machine (1), wherein the knife has a direction of movement (Z) and a cutting edge (41) whose edge preferably extends at an angle (α) to the direction of movement (Z), characterized by , that the cutting edge (41) is toothed. [2] Knife according to claim 1, characterized by , that the cutting edge has a toothing (46) which is formed by parallel, preferably V-shaped in cross-section, recesses over the width of the cutting edge (41). [3] Knife (4) according to claim 1 or 2, characterized by , that it is designed as a hook knife and the cutting edge (41) is arranged on a head section (42) of the knife (4). [4] Knife (4) according to any of the preceding claims, characterized by , that it has a coupling section (43) opposite a head section (42) in the direction of movement (Z) for mechanical coupling with the knife drive of a sewing machine or overlock machine (1). [5] Sewing or overlocking machine (1) with a stitch plate (2) for supporting a material to be sewn or overlocked, at least one feed dog (3) arranged in the area of ​​the stitch plate (2) for advancing the material to be processed in a sewing direction (X), at least one sewing needle (6, 7), a presser foot (9) for pressing the material to be processed against the stitch plate (2) and / or the feed dog (3) and a knife (4) movable in a direction of movement (Z) for cutting the material to be processed during the sewing or overlocking process, wherein the knife (4) is designed according to one of the preceding claims. [6] Sewing or overlocking machine (1) according to claim 5, characterized by that the direction of movement preferably runs perpendicular to the sewing direction (X). [7] Sewing or overlocking machine (1) according to claim 5 or 6, characterized by , that a fixed counter-blade is arranged in the effective area of ​​the movable blade (4).

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