Reverse stitching device, sewing machine and reverse stitching method

Abstract

The present invention relates to a reverse stitching device, a sewing machine, and a reverse stitching method. The reverse stitching device is used to sew a garment body with a shoulder seam to a collar strip, and the reverse stitching device includes a sewing assembly, a reverse stitching assembly, and a control assembly. The sewing assembly is used to sew the garment body to the collar strip; the reverse stitching assembly includes a reverse stitching drive and a material shifting member connected to the reverse stitching drive; the control assembly is electrically connected to the sewing assembly and the reverse stitching assembly, and is used to control the reverse stitching drive to drive the material shifting member to rotate so as to shift the shoulder seam in the direction of the sewing material movement. The reverse stitching process of the present invention does not require the machine to stop, and can achieve automatic reverse stitching, significantly improving work efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of sewing equipment, in particular to a reverse stitching device, a sewing machine and a reverse stitching method. Background Art

[0002] When the collar machine is making a round neck, the body of the garment is placed above the collar strip, and the shoulder seam of the garment is on the upper surface of the garment. However, according to the garment craftsmanship requirements, the shoulder seam needs to be reversed to the back panel, so one of the two shoulder seams on the garment needs to be reversed when entering the presser foot.

[0003] In traditional technology, in order to perform reverse sewing, when the shoulder seam is about to enter the presser foot, the machine needs to be stopped first, the presser foot needs to be lifted, and the worker uses hands or other tools to reverse the shoulder seam in the direction of fabric advance, and then starts the spindle motor to start sewing.

[0004] However, the current sewing device has the problems of wasting manpower and low working efficiency. Summary of the Invention

[0005] Based on this, it is necessary to provide a reverse sewing device, a sewing machine and a reverse sewing method to address the above technical problems. The reverse sewing process does not require stopping the machine for processing, and can achieve automatic reverse sewing, which greatly improves work efficiency.

[0006] The present disclosure provides a reverse sewing device for sewing a garment body with a shoulder seam to a collar strip, the reverse sewing device comprising:

[0007] Sewing assembly, used to sew the body of the garment to the collar strip;

[0008] A reverse stitch assembly, the reverse stitch assembly comprising a reverse stitch driving member and a material shifting member drivingly connected to the reverse stitch driving member; and

[0009] The control component is electrically connected to the sewing component and the reverse stitching component, and is used to control the reverse stitching drive member to drive the material shifting member to rotate so as to shift the shoulder seam in the direction of sewing material movement.

[0010] The reverse stitching device provided in the embodiment of the present invention has a control component electrically connected to the sewing component for sensing the number of sewing needles of the sewing component. The control component is electrically connected to the reverse stitching component for determining, according to the number of sewing needles, the timing for the reverse stitching driving member to drive the material shifting member to rotate so as to shift the shoulder seam in the direction of movement of the sewing material. The control effect is good, and automatic reverse stitching can be achieved without stopping the machine during the reverse stitching process.

[0011] In one embodiment, the control component includes a sensor, an operating panel connected to the sensor, and a control module electrically connected to the sensor and the operating panel. The sensor and the sewing component are correspondingly arranged to sense the number of sewing needles, and the operating panel is used to set a first preset number of needles; the control module is used to control the reverse sewing drive member to drive the material shifting member to rotate forward to approach the material pressing position when the sensed number of sewing needles reaches the first preset number of needles.

[0012] In this configuration, the control module is electrically connected to the sensor and the operation panel, and is configured to compare the sewing stitch count sensed by the sensor with a first preset stitch count set on the operation panel. When the sewing stitch count equals the first preset stitch count, the control module controls the reverse stitching drive member to drive the material shifting member to rotate forward, so that the material shifting member approaches the material pressing position, thereby shifting the shoulder seam in the reverse direction of the sewing material.

[0013] In one embodiment, the operation panel is used to set a second preset number of stitches; the control module is used to control the reverse stitch drive to drive the material shifting member to rotate in the opposite direction to move away from the material pressing position when the sensed number of sewing stitches reaches the second preset number of stitches.

[0014] In this configuration, the control module is electrically connected to the sensor and the operation panel, and then compares the sewing stitch count sensed by the sensor with a second preset stitch count set on the operation panel. When the sewing stitch count equals the second preset stitch count, the control module controls the backstitch drive to drive the material shifting member to rotate in the opposite direction, thereby raising the material shifting member and moving it away from the material pressing position.

[0015] In one embodiment, the backstitch driving member is one of a rotary cylinder, a stepping motor and a servo motor.

[0016] In one embodiment, the material-moving member includes a connecting arm radially extending from the backstitch driving member and a material-pressing arm axially extending from the connecting arm.

[0017] With such arrangement, the backstitch driving member drives the pressing arm to rotate by driving the connecting arm.

[0018] In one embodiment, the sewing assembly includes a sewing drive member and a presser foot, and the sewing drive member is drivingly connected to the presser foot to press the body and the collar for sewing.

[0019] With such arrangement, the sewing drive member is connected to the presser foot drive to press the garment body and the collar strip, thereby preventing the garment body and / or the collar strip from deflecting during sewing.

[0020] According to another aspect of the present application, the present application further provides a sewing machine, comprising:

[0021] sewing machine body; and

[0022] The reverse stitching device as described in any one of the above items is installed on the sewing machine body.

[0023] In this way, the reverse stitching device is installed on the sewing machine body, so that when the sewing machine needs to be stopped during the sewing process, automatic reverse stitching can be achieved, and the degree of automation is high.

[0024] According to another aspect of the present application, the present application further provides a backstitching method, comprising:

[0025] Step S1: Sewing the body with shoulder seams to the collar strips using sewing components;

[0026] Step S2: Control the reverse sewing driving member to drive the material shifting member to rotate to shift the shoulder seam back in the direction of sewing material movement to continue the sewing action.

[0027] With such an arrangement, the tilting direction of the shoulder seam can be changed to be consistent with the movement direction of the sewing material by controlling the reverse sewing drive member to drive the material shifting member to rotate, thereby realizing automatic reverse sewing processing without stopping the machine, with good processing effect and improved work efficiency.

[0028] In one embodiment, step S2 further includes:

[0029] Step S21: Counting the number of sewing needles of the sewing assembly;

[0030] Step S22: Setting the first preset number of stitches M1 through the operation panel;

[0031] Step S23: determining whether the number of sewing stitches N is equal to the first preset number of stitches M1;

[0032] When N is less than M1, execute step S21;

[0033] When N is equal to M1, execute step S24;

[0034] Step S24: controlling the reverse stitching driving member to drive the material shifting member to rotate forward to approach the material pressing position.

[0035] This arrangement is used to determine the timing for the reverse stitching driver to drive the material shifter to rotate so as to shift the shoulder seam in the direction of the material movement according to the number of sewing stitches. When the number of sewing stitches N is equal to the first preset number of stitches M1, the reverse stitching driver drives the material shifter to rotate forward to approach the material pressing position, shifting the shoulder seam in the direction of the material movement to achieve automatic reverse stitching. In one embodiment, step S20 further includes:

[0036] Step S25: Setting a second preset number of needles M2 through the operation panel, wherein the second preset value M2 is greater than the first preset number of needles M1;

[0037] Step S26: Determine whether the number of sewing needles N is greater than M2;

[0038] When N is less than M2, execute step S27;

[0039] When N is greater than or equal to M2, execute step S28;

[0040] Step S27: controlling the material-displacing member to stay at the material-pressing position to keep the shoulder seam in the direction of the sewing movement;

[0041] Step S28: controlling the reverse stitch driving member to drive the material shifting member to rotate in the reverse direction to move away from the material pressing position.

[0042] With this arrangement, when the number of sewing stitches N is greater than or equal to the first preset number of stitches M1 and less than M2, the material shifter stays at the material pressing position, maintaining the tilting direction of the shoulder seam so that the tilting direction of the shoulder seam is consistent with the direction of movement of the sewing material, thereby achieving automatic reverse stitching. When the number of sewing stitches N is greater than or equal to the second preset number of stitches M2, the reverse stitching drive member drives the material shifter to rotate in the opposite direction, away from the material pressing position and back to the initial position. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Schematic diagram of the three-dimensional structure of the sewing machine of the present invention;

[0044] Figure 2 for Figure 1 A large picture is posted at the middle circle A;

[0045] Figure 3 is a flow chart of the reverse stitching method of the present invention;

[0046] Figure 4 This is a flow chart of the forward rotation in the present invention;

[0047] Figure 5 This is a flow chart of reverse rotation in the present invention.

[0048] Description of Figure Numbers:

[0049] 100. Garment body; 110. Shoulder seam; 10. Sewing assembly; 20. Reverse stitch assembly; 21. Reverse stitch drive; 22. Material shifter; 221. Connecting arm; 222. Material pressing arm; 30. Sewing machine body. DETAILED DESCRIPTION

[0050] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0051] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0052] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0053] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0054] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0055] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0056] According to the garment craftsmanship requirements, the shoulder seams 110 need to be reversed toward the back panel, so one of the two shoulder seams 110 on the garment body 100 needs to be reversed when entering the presser foot.

[0057] In the conventional technology, in order to perform reverse sewing, when the shoulder seam 110 is about to enter the presser foot, the machine needs to be stopped first, the presser foot needs to be lifted, and the worker uses hands or other tools to reverse the shoulder seam 110 in the direction of fabric advance, and then starts the spindle motor to run sewing, which wastes manpower and has low work efficiency.

[0058] See also Figures 1 to 5 The present invention provides a reverse sewing device, a sewing machine and a reverse sewing method. The reverse sewing process does not require stopping the machine for processing, and can realize automatic reverse sewing, thereby greatly improving work efficiency.

[0059] Combine Figure 1 and Figure 2 As shown, the present application provides a sewing machine, which includes a sewing machine body 30 and a reverse stitching device, which is installed on the sewing machine body 30.

[0060] Specifically, the reverse stitching device is installed on the sewing machine body 30, so that when the sewing machine needs to be stopped during the sewing process, automatic reverse stitching can be achieved, which has a high degree of automation.

[0061] The present application further provides a reverse sewing device, which is used to sew a body 100 with a shoulder seam 110 to a collar strip. The reverse sewing device includes a sewing assembly 10, a reverse sewing assembly 20 and a control assembly. The sewing assembly 10 is used to sew the body 100 to the collar strip; the reverse sewing assembly 20 includes a reverse sewing drive 21 and a material shifting member 22 driven and connected to the reverse sewing drive 21; the control assembly is electrically connected to the sewing assembly 10 and the reverse sewing assembly 20, and is used to control the reverse sewing drive 21 to drive the material shifting member 22 to rotate so as to shift the shoulder seam 110 in the direction of sewing material movement.

[0062] The reverse stitching device provided in the embodiment of the present disclosure has a control component electrically connected to the sewing component 10 for sensing the number of sewing stitches of the sewing component 10, and a control component electrically connected to the reverse stitching component 20 for determining, based on the number of sewing stitches, the timing for the reverse stitching driving component 21 to drive the material shifting component 22 to rotate so as to shift the shoulder seam 110 in the direction of movement of the sewing material. The control effect is good, and automatic reverse stitching can be achieved without stopping the machine during the reverse stitching process.

[0063] In some embodiments, the control component includes a sensor (not shown in the figure), an operating panel connected to the sensor (not shown in the figure), and a control module (not shown in the figure) electrically connected to the sensor and the operating panel. The sensor is corresponding to the sewing component 10 and is used to sense the number of sewing needles. The operating panel is used to set a first preset number of needles; the control module is used to control the reverse sewing drive 21 to drive the material shifting member 22 to rotate forward to approach the material pressing position when the sensed number of sewing needles reaches the first preset number of needles.

[0064] It can be understood that the control module is electrically connected to the sensor and the operation panel, and is used to compare the number of sewing stitches sensed by the sensor with the first preset number of sewing stitches set by the operation panel. When the number of sewing stitches is equal to the first preset number of sewing stitches, the control module controls the reverse stitching drive member 21 to drive the material picking member 22 to rotate forward (to Figure 1 For example, that is, clockwise rotation), the material shifting member 22 is used to move closer to the material pressing position to shift the shoulder seam 110 in the direction of sewing material movement. It should be explained that the material pressing position in this embodiment refers to a certain position on the workbench of the sewing machine body 30. When the garment body 100 moves to the material pressing position, the reverse sewing driving member 21 drives the material shifting member 22 to rotate forward to shift the shoulder seam 110 in the direction of sewing material movement, and the shoulder seam 110 is pressed at the material pressing position by the material shifting member 22.

[0065] Furthermore, the operation panel can also set a second preset number of needles; the control module is used to control the reverse stitching drive 21 to drive the material-dispensing member 22 to rotate in the opposite direction to move away from the material pressing position when the number of sewing needles sensed by the sensor reaches the second preset number of needles. It can be understood that the control module is electrically connected to the sensor and the operation panel, and then compares the number of sewing needles sensed by the sensor with the second preset number of needles set by the operation panel. When the number of sewing needles is equal to the second preset number of needles, the control module controls the reverse stitching drive 21 to drive the material-dispensing member 22 to rotate in the opposite direction (to move away from the material pressing position). Figure 1 For example, that is, counterclockwise rotation), it is used to lift the material diverter 22 to move the material diverter 22 away from the material pressing position.

[0066] Optionally, the reverse stitching drive member 21 in this embodiment is one of a rotary cylinder, a stepping motor and a servo motor. The reverse stitching drive member 21 is used to drive the material picking member 22 to rotate, and can be adaptively selected according to different requirements such as actual adjustment speed and operation stability.

[0067] Preferably, the material shifting member 22 includes a connecting arm 221 extending radially from the reverse stitching driving member 21 and a material pressing arm 222 extending axially from the connecting arm 221. Specifically, the reverse stitching driving member 21 drives the connecting arm 221 to drive the material pressing arm 222 to rotate, and the connecting arm 221 and the material pressing arm 222 are integrally connected in an L-shape.

[0068] In other embodiments, the pressing arm 222 may also be a sheet-like structure with a certain degree of deformation, as long as it can change the tilting direction of the shoulder seam 110. In addition, the sheet-like pressing arm 222 will not damage the fabric when tilting the shoulder seam 110 in the direction of sewing movement.

[0069] In some embodiments, the sewing assembly 10 includes a sewing drive and a presser foot, wherein the sewing drive is drivably connected to the presser foot to press the garment body 100 and the collar strip to perform sewing. Specifically, the garment body 100 and / or the collar strip can be prevented from deflecting during sewing.

[0070] According to another aspect of this application, please refer to Figure 3 , the present application further provides a backstitching method, comprising:

[0071] Step S1: Using the sewing assembly 10, sewing the body 100 with the shoulder seam 110 to the collar strip;

[0072] Step S2: Control the reverse sewing driving member 21 to drive the material shifting member 22 to rotate to shift the shoulder seam 110 back to the direction of sewing material movement to continue the sewing action.

[0073] It should be noted that before sewing, due to the garment process, the tilting direction of the shoulder seam 110 is opposite to the direction of movement of the sewing material. During sewing, the reverse sewing method can change the tilting direction of the shoulder seam 110 to be consistent with the direction of movement of the sewing material by controlling the reverse sewing drive member 21 to drive the material shifting member 22 to rotate, thereby achieving automatic reverse sewing without stopping the machine, achieving good processing effect and improving work efficiency.

[0074] Please refer to Figure 4 In some embodiments, step S2 further includes:

[0075] Step S21: Counting the number of sewing needles of the sewing assembly 10;

[0076] Step S22: Setting the first preset number of stitches M1 through the operation panel;

[0077] Step S23: determining whether the number of sewing stitches N is equal to the first preset number of stitches M1;

[0078] When N is less than M1, execute step S21;

[0079] When N is equal to M1, execute step S24;

[0080] Step S24: controlling the reverse stitching driving member 21 to drive the material shifting member 22 to rotate forward to approach the material pressing position.

[0081] It is worth mentioning that the control component is used to determine the timing for the reverse stitch driving member 21 to drive the material shifting member 22 to rotate so as to shift the shoulder seam 110 in the direction of the material movement according to the number of sewing stitches. Specifically, the sewing assembly 10 is used to sew the garment body 100 with the collar strip. During the sewing process, the sensor is used to sense the number of sewing stitches N. When it is detected that the number of sewing stitches N is equal to the first preset number of stitches M1, the reverse stitch driving member 21 drives the material shifting member 22 to rotate forward to approach the material pressing position, shifting the shoulder seam 110 in the direction of the material movement (to Figure 1 For example, the movement direction of the sewing material is from right to left), and then the sewing assembly 10 performs automatic backstitching on the basis of the material shifting member 22 pressing the shoulder seam 110, and the backstitching effect is good, and there is no need to stop the machine for manual operation.

[0082] Please refer to Figure 5 Furthermore, step S20 further includes:

[0083] Step S25: Setting a second preset number of needles M2 through the operation panel, wherein the second preset value M2 is greater than the first preset number of needles M1;

[0084] Step S26: Determine whether the number of sewing needles N is greater than M2;

[0085] When N is less than M2 (at this time, M1<N<M2 is satisfied), step S27 is executed;

[0086] When N is greater than or equal to M2, execute step S28;

[0087] Step S27: Controlling the material-displacing member 22 to stay at the material-pressing position to keep the shoulder seam 110 tilted in the direction of sewing movement;

[0088] Step S28: controlling the reverse stitching driving member 21 to drive the material shifting member 22 to rotate in the reverse direction to move away from the material pressing position.

[0089] It should be noted that when the number of sewing stitches N is greater than or equal to the first preset number of stitches M1 and less than M2, the material disengaging member 22 remains at the material pressing position, pressing the shoulder seam 110 and maintaining the tilting direction of the shoulder seam 110, so that the tilting direction of the shoulder seam 110 is consistent with the direction of movement of the sewing material to achieve automatic reverse sewing. When the number of sewing stitches N is greater than or equal to the second preset number of stitches M2, the reverse sewing driving member 21 drives the material disengaging member 22 to rotate in the opposite direction to move away from the material pressing position, and the material disengaging member 22 returns to its initial position.

[0090] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0091] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A backstitching device for sewing a garment body (100) with a shoulder seam (110) to a collar strip, characterized in that: The reverse stitching device comprises: A sewing assembly (10) for sewing the body (100) to the collar strip; A reverse stitch assembly (20), the reverse stitch assembly (20) comprising a reverse stitch driving member (21) and a material shifting member (22) drivingly connected to the reverse stitch driving member (21); and a control assembly, the control assembly being electrically connected to the sewing assembly (10) and the reverse stitching assembly (20), and being used to control the reverse stitching driving member (21) to drive the material shifting member (22) to rotate so as to shift the shoulder seam (110) in the direction of sewing material movement; The control component comprises a sensor, an operating panel connected to the sensor, and a control module electrically connected to the sensor and the operating panel, wherein the sensor and the sewing component (10) are correspondingly arranged to sense the number of sewing needles, and the operating panel is used to set a first preset number of needles; the control module is used to control the reverse stitch driving member (21) to drive the material shifting member (22) to rotate forward to approach the material pressing position when the sensed number of sewing needles reaches the first preset number of needles; The operation panel is used to set a second preset number of stitches; the control module is used to control the reverse stitch driving member (21) to drive the material shifting member (22) to rotate in the reverse direction to move away from the material pressing position when the sensed number of sewing stitches reaches the second preset number of stitches.

2. The reverse stitching device according to claim 1, characterized in that: The reverse stitching driving member (21) is one of a rotary cylinder, a stepping motor and a servo motor.

3. The reverse stitching device according to claim 1, characterized in that The material shifting member (22) comprises a connecting arm (221) extending radially from the backstitch driving member (21) and a material pressing arm (222) extending axially from the connecting arm (221).

4. The reverse stitching device according to claim 1, characterized in that The sewing assembly (10) comprises a sewing drive member and a presser foot, wherein the sewing drive member is drivingly connected to the presser foot and is used to press the garment body (100) and the collar strip for sewing.

5. A sewing machine, characterized in that: include: a sewing machine body (30); and The reverse stitching device according to any one of claims 1 to 4, wherein the reverse stitching device is mounted on the sewing machine body (30).

6. A backstitching method, characterized in that: For sewing a garment body (100) with a shoulder seam (110) to a collar strip by means of a reverse stitching device according to any one of claims 1 to 4, comprising: Step S1: Using a sewing assembly (10), sewing a garment body (100) with a shoulder seam (110) to a collar strip; Step S2: controlling the reverse sewing driving member (21) to drive the material shifting member (22) to rotate so as to shift the shoulder seam (110) in the direction of movement of the sewing material to continue the sewing action.

7. The backstitching method according to claim 6, characterized in that: Step S2 also includes: Step S21: counting the number of sewing needles of the sewing assembly (10); Step S22: Setting the first preset number of stitches M1 through the operation panel; Step S23: determining whether the number of sewing stitches N is equal to the first preset number of stitches M1; When N is less than M1, execute step S21; When N is equal to M1, execute step S24; Step S24: controlling the reverse stitch driving member (21) to drive the material shifting member (22) to rotate forward to approach the material pressing position.

8. The backstitching method according to claim 7, wherein: Step S20 further includes: Step S25: Setting a second preset number of needles M2 through the operation panel, wherein the second preset value M2 is greater than the first preset number of needles M1; Step S26: Determine whether the number of sewing needles N is greater than M2; When N is less than M2, execute step S27; When N is greater than or equal to M2, execute step S28; Step S27: controlling the material-dispensing member (22) to stay at the material-pressing position to keep the shoulder seam (110) tilted in the direction of sewing movement; Step S28: controlling the reverse stitch driving member (21) to drive the material shifting member (22) to rotate in the reverse direction to move away from the material pressing position.

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