STITCH FORMING TOOL ASSEMBLY FOR A SEWING DEVICE AND SEWING DEVICE HAVING SUCH ASSEMBLY - Patent application

Abstract

A stitch-forming assembly (6) for a sewing device is used to create a double chainstitch (7). A sewing needle (8) of the assembly (6) is drivable up and down in a needle stitch direction (z) perpendicular to the material to be sewn and is designed to guide a needle thread (10). A looper (12) of the assembly (6) is designed to guide a looper thread (18) and for oscillatory movement in an oscillatory movement plane (xz). The oscillatory movement plane is stretched along the double chainstitch (7) by the needle stitch direction (z) and by the sewing direction (x). The movement path of the looper (12) is entirely within the oscillatory movement plane (xz) during the entire double chainstitch. This results in a stitch-forming tool assembly in which the looper drive is particularly simplified.

Description

[Technical field]

[0001] This patent application claims priority from German patent application DE102019219814.7, the contents of which are incorporated herein by reference.

[0002] The present invention relates to a stitch forming tool assembly for a sewing machine that produces a double chainstitch seam. The present invention further relates to a sewing machine having such an assembly. [Background technology]

[0003] A double chainstitch sewing machine is known from DE 10 20 05 13 A device for adjusting a sewing machine looper is known from DE 10 20 05 13 A device for straightening thread loops in a double chainstitch sewing machine is disclosed in DE 10 20 05 13 A device for removing loopers in a ... [Prior art documents] [Patent documents]

[0004] [Patent Document 1] DD111102 A1 [Patent Document 2] DE2901582C2 [Patent Document 3] DE104963C [Patent Document 4] DE3935779C1 [Patent Document 5] US6095069 [Patent Document 6] DE667052C Summary of the Invention [Problem to be solved by the invention]

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to further develop a stitch-forming tool assembly of the type described above, in particular so that the looper drive is simplified. [Means for solving the problem]

[0006] This object is achieved according to the invention by a stitch forming tool assembly having the features set out in claim 1.

[0007] According to the present invention, it has been found that it is not absolutely necessary to provide a looper movement path in a double chainstitch sewing device in which the looper performs an avoidance movement relative to the sewing needle perpendicular to the plane of the looper's oscillation movement. US Pat. No. 5,399,433 and US Pat. No. 5,499,433 show prior art looper drives with correspondingly complex designs which provide such an elliptical avoidance movement path. Correspondingly complex drives can be omitted in the assembly according to the present invention.

[0008] In the assembly according to the invention, the sewing direction is in the plane of the oscillating movement of the looper, which is also referred to as an in-line system. The looper does not perform a deflection movement perpendicular to the plane of the oscillating movement. The stitch forming tool assembly may be constructed so that it does not require spreader fingers for spreading the thread loops and correspondingly for facilitating threading into the thread loops. Such spreader fingers, which may be omitted here, are known by prior use evident from chain stitch sewing machines of the type Pfaff 5626.

[0009] The central longitudinal axis of the needle is spaced from the needle tip of the needle, and this spacing from the needle tip allows for orientation of the needle relative to the looper, which facilitates unhindered relative movement of these stitch forming components during a stitch forming sequence.

[0010] In the assembly according to the invention, the needle can also be designed so that it moves in just one direction only, namely the needle stitch direction, up and down, ie so that it does not perform an evasive movement relative to the looper.

[0011] This is particularly true for claims 1 This applies to designs that comply with the following:

[0012] Claim 2 The sewing device according to has those advantages already explained above in relation to the stitch-forming tool assembly. The sewing device may comprise a sewing machine or a sewing automat, for which the stitch-forming tool assembly forms a component. The sewing device may also comprise a robot that can control / adjust the sewing head with the stitch-forming tool assembly to move in multiple degrees of freedom, so that even sewing material of complex geometry can be provided with defined seams, in particular seams that extend three-dimensionally in space. The sewing device may thus be a sewing robot, the sewing head of which is movable by multiple degrees of freedom in translation or rotation, or it may be a sewing machine.

[0013] Embodiments of the invention are explained in more detail below with reference to the drawings. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 shows a highly schematic side view of a sewing device in the form of a sewing robot with stitch forming components shown that create a double chain seam. [Diagram 2] In a view rotated by 90° about the z-axis compared to FIG. 1, the stitch-forming parts are shown together with a support for the material to be sewn during the creation of the test seam. [Diagram 3] 3 shows a schematic plan view of a portion of a sewing needle and a looper as viewed from a viewing direction III in FIG. 2. [Figure 4] In an illustration similar to FIG. 2, further instantaneous relative positions of the stitch forming tools with respect to one another are shown during the formation sequence of the double chain stitch of the test seam. [Diagram 5] In an illustration similar to FIG. 2, further instantaneous relative positions of the stitch forming tools with respect to one another are shown during the formation sequence of the double chain stitch of the test seam. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 1 shows very diagrammatically the main components of a sewing device 1 designed as a sewing robot. The sewing device 1 comprises a C-shaped frame 2 having an arm 3, a base plate 4 and a stand 5 connecting the arm 3 to the base plate 4.

[0016] One component of the sewing device 1 is a drive, not shown in more detail, by means of which the frame 2 can be moved in several degrees of freedom, translational or rotational, for example 3, 4, 5 or 6 degrees of freedom. Such drives are known in connection with industrial robots. The sewing device 1 can therefore be designed as a sewing robot.

[0017] Figure 1 further shows a Cartesian xyz coordinate system for ease of layout. The x-axis is perpendicular to the drawing plane of Figure 1 and extends outside it. The y-axis in Figure 1 extends to the right, parallel to the extension of the arm 3 and base plate 4. The z-axis in Figure 1 extends upwards, parallel to the extension of the stand 5. The axial directions x, y and z also apply in the following figures.

[0018] Part of the sewing apparatus 1 is a stitch forming tool assembly 6 which creates a double chain stitch 7, for which a pattern is shown in Figure 2 and in Figures 4 and 5 respectively. The sewing direction extends along the x direction, i.e. perpendicular to the yz plane defined by the C-shape of the frame 2.

[0019] The assembly 6 has a sewing needle 8 which is held by a needle bar 9. The needle bar 9 and with it the sewing needle 8 are movable up and down in the needle stitch direction along a z-axis perpendicular to the material to be sewn, not shown in the drawing. The sewing needle 8 is designed to guide a needle thread 10, also called the upper thread. For this purpose, the sewing needle 8 has an eye 11.

[0020] The stitch forming assembly 6 is supported by a driven looper carrier 13, which is hook-shaped in the side views according to FIGS.

[0021] The looper 12 has a bent design (offset design). In the region of the looper tip 15 and at its opposite end, the threading section 14 of the looper 12 has respective thread passage openings 16, 17 for the looper thread 18, also called the lower thread. The looper 12 is designed to guide the looper thread 18. Based on the drive of the looper carrier 13, which is not shown in more detail, the looper is further designed to oscillate in an oscillating movement plane. The oscillating movement plane coincides with the xz plane, i.e. it is stretched along the double chainstitch 7 by the needle stitch direction on the one hand and by the sewing direction x on the other hand. The movement path of the looper lies entirely in the oscillating movement plane xz during the full double chainstitch, snapshots of which are shown in Figs. 2, 4 and 5. Thus, perpendicular to this oscillating movement plane xz, the looper does not perform any avoidance movements.

[0022] The sewing direction x therefore lies in the plane xz of oscillating movement of the looper 12. The sewing device 1 therefore represents an in-line system.

[0023] The stitch forming assembly 6 does not include spreader fingers, such spreader fingers not present here being known from prior use evident, for example, from chain stitch sewing machines of the type Pfaff 5626.

[0024] FIG. 3 shows a schematic plan view of the interrupted section of the threading section 14 of the looper 12 and of the sewing needle 8. The representation according to FIG. 3 is enlarged, especially with regard to the diameter of the sewing needle 8. The direction of view in FIG. 3 is along the central longitudinal axis 19 of the sewing needle 8. Also shown in FIG. 3 is the piercing point of the needle tip 20, which passes through the illustrated plane of FIG. 3. From this illustration it can be seen that in the case of the sewing needle 8, the central longitudinal axis 19 is separated from the needle tip 20 by a distance δy. The sewing needle 8 is therefore not rotationally symmetric in the region of the needle tip 20, which is offset by a distance δy with respect to the axis of symmetry of the needle body, which coincides with the central longitudinal axis 19. As shown in FIG. 3, when the sewing needle 8 is mounted, the needle tip 20 is offset by a distance δy from the central longitudinal axis 19 perpendicular to the plane of oscillatory movement xz. When the threading section 14 of the looper 12 passes the needle tip 20 during stitch formation, the central longitudinal axis 19 is located between the needle tip 20 and the threading section 14 of the looper 12, i.e., between the needle tip 20 and the looper 12, as also shown in FIG.

[0025] This eccentricity of the needle tip 20 makes it easier to guide the sewing needle 8 through the threading section 14, particularly when the needle tip 20 is inserted into the loop of the looper thread 18 as shown in FIG.

[0026] The threading section 14 is guided at a very small distance beyond the tip section of the sewing needle 8. In principle, the two components 8, 12 can also come into contact with each other.

[0027] 2 further shows a support element 21 for the material to be sewn and a presser foot or transport foot for the material to be sewn 22. In the actual sewing operation, the material to be sewn is moved between the support element 21 and the foot 22 in the sewing direction x.

[0028] Figure 4 shows the point in the formation sequence of the double chain stitch when the sewing needle 8 has reached the area of ​​the bottom dead center. At the point in time according to Figure 4, the looper tip 15 is in the area of ​​the right dead center in Figure 4 and has been deflected (bent) to such an extent that, in the projection according to Figure 4, it reaches beyond the section 23 of the needle thread 10 guided outside the eye 11.

[0029] FIG. 5 shows the point in time of the stitch formation sequence at which the threading section 14 is threaded through the needle thread loop that was formed in the meantime in the needle thread section 23 due to the reversal of the movement of the sewing needle 8. The looper thread 18 is also guided through this loop of the needle thread section 23 in the region of the thread passage opening 16 of the threading section 14. During the next threading of the next stitch formation sequence (see FIG. 2), the sewing needle again threads the looper thread 18 over this needle thread loop in the −x direction, and after the retraction of the threading section 14 of the looper 12, the previously formed loop of the needle thread section 23, entangled with the looper thread 18, is released from the threading section 14, as can be seen from FIG. 4. This results in the familiar double loop stitch formation mechanism. The seam 7 that is formed therefore extends in the +x direction.

[0030] The assembly 6 may also be prepared as a conversion kit for a sewing device. [Explanation of symbols]

[0031] 1 Sewing device 6 Stitch Forming Tool Assembly 7 Double chain stitch 8. Sewing Needles 10 Needle thread 12 Looper 18 Looper thread 19 Central Longitudinal Axis 20 Needle Tip x Sewing direction z Needle stitch direction xz vibration moving plane

Claims

1. A stitch forming tool assembly (6) for a sewing device (1) for making a double chain stitch (7), comprising: a sewing needle (8) movable up and down in a needle stitch direction (z) perpendicular to the material to be sewn and designed to guide a needle thread (10); A looper (12) designed to guide a looper thread (18) and to move in an oscillatory motion in a plane of oscillatory motion (xz), The vibration movement plane (xz) is Tensioned by the needle stitch direction (z), and The double chain stitch (7) is tensioned in the sewing direction (x), the path of movement of said looper (12) is entirely within said oscillating movement plane (xz) during the entire double chain stitch; When the sewing needle (8) is placed, a needle tip (20) of the sewing needle (8) is spaced apart from a central longitudinal axis (19) of the sewing needle (8) perpendicular to the vibration movement plane (xz); the sewing needle (8) is designed to move up and down only in the needle stitch direction (z); and When the looper (12) passes the needle tip (20) during stitch formation, the central longitudinal axis (19) is between the needle tip (20) and the looper (12). A stitch forming tool assembly (6).

2. A sewing device having the stitch forming tool assembly of claim 1.

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