Mechanism and its working method for simultaneously controlling needle pitch and presser foot lifting by stepper motor

Abstract

This invention relates to a mechanism and its working method for simultaneously controlling the stitch pitch and lifting the presser foot using a stepper motor. It addresses the problems of low precision, difficulty in adjusting the stitch pitch, and cost savings. The technical solution of this invention includes: a stitch pitch drive wheel and a presser foot lifting cam assembly are provided at the output shaft end of the stepper motor; a stitch pitch driven wheel is provided on the stitch pitch cam shaft; a U-shaped groove is provided on the extension line of the center hole of the stitch pitch driven wheel; two fan-shaped notches are fixed symmetrically on both sides of the U-shaped groove; a stitch pitch cam connecting rod connects the stitch pitch driven wheel and the stitch pitch adjustment frame; a knee control rod is provided on the left side of the stepper motor output shaft; the top of the knee control rod is connected to a knee control lifting lever; a presser foot lifting sliding block is provided on the hexagonal head screw of the lifting clamp; the presser foot lifting sliding block has a square notch; and circular through holes are arranged on both sides of the notch; the small hole end of the Z-shaped presser foot lifting cam rod is fixed to the presser foot lifting sliding block by a pin; one end of the pin is fixed with an E-type retaining spring.

Description

Technical Field

[0001] This invention relates to the field of sewing machine technology, specifically to a mechanism and its working method that uses a stepper motor to simultaneously control the stitch length and the lifting of the presser foot. Background Technology

[0002] Most current double-needle machines rely on manual adjustment of the needle spacing using a needle spacing knob or are controlled by a single stepper motor. This results in low precision and difficulty in adjusting the needle spacing. Furthermore, the separate control of the needle spacing adjustment and presser foot lifting by the stepper motor and electromagnet increases costs and wastes resources.

[0003] Due to the different feeding method, the double-needle sewing machine is difficult to apply. Unlike ordinary single-needle flat sewing machines, the double-needle machine feeds the needle bar and the feed dog simultaneously. The adjustment of the stitch length is not only the range of motion of the feed dog, but also the swing amplitude of the needle bar. This increases the difficulty of adjusting the accuracy and stability of the stitch length. Summary of the Invention

[0004] In view of this, in order to solve the problems of low accuracy, difficulty in adjustment and cost saving in needle spacing adjustment, the present invention provides a mechanism and its working method that simultaneously controls needle spacing and presser foot lifting by a stepper motor. The operation process is to control the needle spacing drive wheel and the presser foot lifting cam to rotate and drive the connecting rod through the forward and reverse rotation of the stepper motor to realize the needle spacing adjustment and presser foot lifting functions.

[0005] To address the problems existing in the prior art, the technical solution of this invention is: a mechanism that simultaneously controls the stitch pitch and the lifting of the presser foot using a stepper motor, comprising a stepper motor, a knee control lever, a knee control lifting lever, and a presser foot assembly. The upper part of the knee control lever is fixedly connected to the knee control lifting lever, and the knee control lifting lever is connected to the left ear of the knee control linkage of the presser foot assembly to realize the up-and-down movement of the presser foot assembly; characterized in that:

[0006] The output shaft of the stepper motor is sequentially fitted with a needle pitch drive wheel, a lifting cam, and a lifting cam cover plate;

[0007] The middle part of the knee control rod is tightened by the left and right lifting clamps. The bottom of the left lifting clamp is movably connected to the lifting sliding block by the hexagonal head screw. The lifting sliding block slides up and down along the hexagonal head screw. The lifting cam rod includes a Z-shaped rod integrally set on the ring. The lifting cam cover plate is fixed on the ring of the lifting cam rod. The upper end of the Z-shaped rod of the lifting cam rod is locked in the U-shaped groove of the lifting sliding block. The lifting cam rod rotates to drive the lifting sliding block to move up and down.

[0008] A needle pitch camshaft is arranged parallel to the output shaft of the stepper motor. The needle pitch driven wheel is fixed on the needle pitch camshaft and cooperates with the needle pitch driving wheel. One end of the needle pitch cam connecting rod is fixed to the needle pitch driven wheel, and the other end is fixed to one side of the needle pitch adjustment frame.

[0009] The needle-pitch drive wheel has a circular structure with an arc-shaped notch on the circle, and a cylindrical head for driving is provided at the end of the arc-shaped notch; the needle-pitch driven wheel has a "U"-shaped groove that mates with the cylindrical head and an arc-shaped surface that mates with the arc-shaped notch.

[0010] The aforementioned lifting cam and lifting cam cover plate are provided with one large and two small round holes in corresponding positions; the lifting cam and lifting cam cover plate are connected to the output shaft of the stepper motor through the large round hole and fixedly connected through the two small round holes.

[0011] The aforementioned lifting and sliding block has a U-shaped groove on one side and a hole for inserting an internal hexagonal head screw from top to bottom on the other side. A pin hole is provided in the middle of the two sides of the U-shaped groove, and a pin is inserted into the pin hole. After the pin passes through the pin hole, it is fixed by an E-type retaining spring.

[0012] The left and right lifting clamps are respectively provided with cylindrical arc surfaces on their opposite surfaces, which are fixed to the knee control rod.

[0013] The aforementioned stitch cam connecting rod is a "Z"-shaped rod, with both ends fixed to the stitch driven wheel and the stitch adjustment frame respectively via shaft screws.

[0014] The aforementioned lifting cam is provided with a step, which is used to engage with the ring of the lifting cam rod.

[0015] The aforementioned left lifting clamp is provided with a threaded through hole running from top to bottom, and an internal hexagonal head screw is fixed in the through hole of the left lifting clamp.

[0016] The aforementioned camshaft is fixed to the housing.

[0017] The working method of the mechanism that simultaneously controls the needle pitch and presser foot lifting by a stepper motor is as follows:

[0018] 1) When the machine is working normally, the presser foot is lowered, and the stepper motor rotates in the forward direction, driving the needle pitch drive wheel to rotate. The cylindrical head of the needle pitch drive wheel and the "U" groove on the needle pitch driven wheel 3 cooperate. Whenever the needle pitch drive wheel rotates by a corresponding angle, it will drive the needle pitch driven wheel to rotate by a corresponding angle. At the same time, the needle pitch cam connecting rod that cooperates with it will make up, down and left and right circular motions, thereby driving the needle pitch adjustment frame to rotate by a certain angle to achieve the adjustment of the needle pitch size.

[0019] 2) During the needle spacing adjustment process, the lifting cam rod drives the lifting sliding block to move. The highest position of the lifting sliding block at the hexagonal head screw is always lower than the fixed position of the left lifting clamp when the current presser foot falls. Therefore, the presser foot is always in contact with the needle plate during this process.

[0020] 3) When the presser foot needs to be lifted, the stepper motor starts to reverse, the cylindrical head of the needle pitch drive wheel separates from the "U" groove on the needle pitch driven wheel, and at the same time the arc surface of the arc notch of the needle pitch drive wheel meshes with the arc surface of the needle pitch driven wheel, the relative position of the needle pitch driven wheel is restricted. When the needle pitch drive wheel continues to rotate, the needle pitch driven wheel is relatively stationary. At this time, the lifting cam rotates and drives the lifting cam rod to move, thereby driving the lifting sliding block to move upward along the internal hexagonal cylindrical head screw. When the upper surface of the lifting sliding block coincides with the lower surface of the left lifting clamp block, it drives it to move upward, then drives the knee control rod to move upward and pushes the knee control lifting lever to rotate, finally lifting the presser foot in the presser foot assembly;

[0021] 4) When sewing needs to be started again, the presser foot falls down. At this time, the stepper motor rotates forward, and the lifting cam rotates, which drives the lifting cam rod to move. This causes the lifting sliding block to move downward along the internal hexagonal cylindrical head screw. The lifting sliding block and the left lifting clamp block separate, and the presser foot in the presser foot assembly falls down. At the same time, the cylindrical head of the stitch length drive wheel engages with the "U" groove on the stitch length driven wheel.

[0022] 5) Steps 1), 2), 3) and 4) constitute a complete motion process. Repeating steps 1)-4) will allow you to control the stitch length and lift the presser foot.

[0023] Compared with the prior art, the advantages of the present invention are as follows:

[0024] 1. This invention uses a cylindrical head of the needle pitch driving wheel and a U-shaped groove of the needle pitch driven wheel in a tangential fit to make the needle pitch setting more precise;

[0025] 2. This invention uses a single stepper motor to simultaneously control the needle pitch adjustment and presser foot lifting, thus eliminating the expensive cost of using an additional stepper motor or electromagnet and saving costs.

[0026] 3. This invention cleverly utilizes the corresponding angles of the forward and reverse rotation of the motor. When the motor rotates forward, the cylindrical head of the needle pitch drive wheel cuts into the "U-shaped groove" of the needle pitch driven wheel, causing it to rotate and drive the needle pitch switcher to rotate. Each rotation corresponds to a different angle, adjusting the needle pitch accordingly. When the motor rotates in reverse, the cylindrical head of the needle pitch drive wheel disengages from the "U-shaped groove." At this time, the needle pitch driven wheel remains relatively stationary due to the cooperation of the arc-shaped notch. At the same time, the motor continues to rotate in the corresponding angle, and the lifting cam rotates along with it, causing the presser foot to lift to the corresponding height. This use of tangential cooperation and dual positioning and guidance of the cylinder makes the structure simpler and more accurate.

[0027] 4. This invention has a simple structure, realizes arbitrary adjustment of the needle pitch and presser foot height, and adds electronic needle pitch adjustment function and electronic presser foot height adjustment function, making it more accurate and easier to operate. All adjustments are made through the operation screen parameters, and the appearance is aesthetically pleasing. Attached Figure Description

[0028] Figure 1 This is a structural diagram of the present invention;

[0029] Figure 2 The needle spacing state reference diagram is used in this invention;

[0030] Figure 3 The reference diagram shows the lifting state of the pressure foot in this invention;

[0031] Figure 4 This is a schematic diagram showing the connection between the driven wheel and the driving wheel of the needle pitch.

[0032] Figure descriptions: 1-Stepper motor, 2-Pitch drive wheel, 3-Pitch driven wheel, 4-Pitch camshaft, 5-Pitch cam connecting rod, 6-Shaft screw, 7-Pitch adjustment bracket, 8-Lifting cam, 9-Lifting cam rod, 10-Lifting cam cover plate, 11-Hex socket head cap screw, 12-Pin, 13-Left lifting clamp, 14-Right lifting clamp; 15-Lifting sliding block, 16-E-type retaining ring, 17-Knee control lever, 18-Knee control lifting lever, 19-Pressure foot assembly; 20-Cylindrical head, 21-Arc-shaped notch, 22-“U”-shaped groove, 23-Arc-shaped surface. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0034] This invention provides a mechanism for simultaneously controlling the stitch pitch and presser foot lifting using a stepper motor, comprising a stepper motor 1, a stitch pitch drive wheel 2, a stitch pitch driven wheel 3, a stitch pitch camshaft 4, a stitch pitch cam connecting rod 5, a shaft screw 6, a stitch pitch adjustment bracket 7, a presser foot lifting cam 8, a presser foot lifting cam rod 9, a presser foot lifting cam cover plate 10, a hexagon socket head cap screw 11, a pin shaft 12, a left lifting clamp 13, a right lifting clamp 14; a presser foot lifting sliding block 15, an E-type retaining ring 16, a knee control lever 17, a knee control lifting lever 18, and a presser foot assembly 19. Figure 1 As shown.

[0035] The aforementioned knee control lever 17 is connected to the left hole of the knee control lifting lever 18 via a shaft screw. The lower hole of the knee control lifting lever 18 is connected to the presser foot assembly 19. The presser foot assembly 19 moves up and down via the left ear of the knee control linkage.

[0036] The aforementioned needle pitch drive wheel 2 has a circular structure with an arc-shaped notch 21 on the circle. The end of the arc-shaped notch has a cylindrical head 20 for driving (the stepper motor required for forward needle pitch adjustment rotates approximately 50 degrees, while at this time the lifting sliding block and the lifting clamping block are separated at an angle of 100 degrees, therefore the presser foot must be in contact with the needle plate). The needle pitch driven wheel 3 has a U-shaped groove 22 that mates with the cylindrical head 20, and an arc-shaped surface 23 that mates with the arc-shaped notch, as shown below. Figure 4 As shown.

[0037] The aforementioned lifting cam 8 and lifting cam cover plate 10 are provided with one large and two small round holes in corresponding positions; the lifting cam 8 is provided with a step, which is engaged with the ring of the lifting cam rod 9, and the lifting cam cover plate 10 is also engaged with the ring of the lifting cam rod 9.

[0038] The output shaft of the aforementioned stepper motor 1 is sequentially fitted with a pitch drive wheel 2, a lifting cam 8, and a lifting cam cover plate 10. The lifting cam cover plate 10 is fixed to the corresponding through hole of the lifting cam 8 by screws. The lifting cam 8 and the lifting cam cover plate 10 are connected to the output shaft of the stepper motor 1 through a large round hole and fixedly connected through two small round holes. A pitch camshaft 4 is arranged parallel to the right side of the output shaft of the stepper motor 1 at the same horizontal level. The pitch driven wheel 3 is fixed on the pitch camshaft 4 and cooperates with the pitch drive wheel 2. When the cylindrical head on the needle pitch drive wheel 2 is in action, it rotates tangentially with the "U"-shaped groove on the needle pitch driven wheel 3. At the same time, the arc surface of the needle pitch drive wheel 2 and the arc notch of the needle pitch driven wheel 3 are used in conjunction. The needle pitch camshaft 4 is fixed on the machine housing. The needle pitch cam connecting rod 5 is a "Z"-shaped rod, and its two ends are fixed to the needle pitch driven wheel 3 and the needle pitch adjusting bracket 7 respectively through the shaft screw 6. A "U"-shaped long groove is provided on the extension line of the center hole of the needle pitch driven wheel 3, and two fan-shaped notches are fixed on both sides of the "U"-shaped long groove and are symmetrical.

[0039] The left lifting clamp 13 and the right lifting clamp 14 are respectively provided with cylindrical arc surfaces on their opposite surfaces, which are fixed to the knee control rod 17. One side of the left lifting clamp 13 is provided with a threaded through hole from top to bottom, and the internal hexagonal head screw 11 is fixed in the through hole of the left lifting clamp 13. The lifting sliding block 15 is provided on the internal hexagonal head screw 11 at the bottom of the left lifting clamp 13 and slides up and down along the internal hexagonal head screw 11 to lift the cam rod 9. The structure includes a Z-shaped rod integrally set on a ring, a lifting cam cover plate 10 fixed on the ring of the lifting cam rod 9, the upper end of the Z-shaped rod of the lifting cam rod 9 is engaged in the U-shaped groove of the lifting sliding block 15, and the lifting sliding block 15 is moved up and down by the rotation of the lifting cam rod 9; a pin hole is provided in the middle of the two sides of the U-shaped groove on one side of the lifting sliding block 15, and a pin shaft 12 is inserted in the pin hole. After the pin shaft 12 passes through the pin hole, it is fixed by an E-type retaining spring 16.

[0040] The present invention provides a method for operating a mechanism that simultaneously controls the needle pitch and the lifting of the presser foot using a stepper motor. The steps are as follows:

[0041] 1) Initially, the machine operates normally. The pressure foot is lowered, as... Figure 2 As shown, the stepper motor 1 rotates in the forward direction, driving the needle pitch drive wheel 2 to rotate. The cylindrical head 20 of the needle pitch drive wheel 2 and the "U"-shaped groove 22 on the needle pitch driven wheel 3 cooperate. At the same time, the arc-shaped notch 21 of the needle pitch drive wheel 2 touches the arc-shaped surface 23 of the needle pitch driven wheel 3. Whenever the needle pitch drive wheel 2 rotates by a corresponding angle, it will drive the needle pitch driven wheel 3 to rotate by a corresponding angle. At the same time, the needle pitch cam connecting rod 5 that cooperates with it will perform up-down and left-right circular motion, thereby driving the needle pitch adjustment frame 7 to rotate by a certain angle to achieve the adjustment of the needle pitch size.

[0042] 2) During the needle spacing adjustment process, the lifting cam rod 9 drives the lifting sliding block 15 to move. The highest position of the lifting sliding block 15 at the internal hexagonal head screw 11 is always lower than the fixed position of the left lifting clamp 13 when the current presser foot falls. Therefore, the presser foot is always in contact with the needle plate during this process.

[0043] 3) When it is necessary to lift the presser foot, such as Figure 3 As shown, the stepper motor 1 starts to reverse, the cylindrical head of the needle pitch drive wheel 2 separates from the "U" groove on the needle pitch driven wheel 3, and at the same time the arc surface of the arc notch 21 of the needle pitch drive wheel 2 meshes with the arc surface of the needle pitch driven wheel 3, the relative position of the needle pitch driven wheel 3 is restricted, and when the needle pitch drive wheel 2 continues to rotate, the needle pitch driven wheel 3 is relatively stationary. At this time, the lifting cam 8 rotates and drives the lifting cam rod 9 to move, thereby driving the lifting sliding block 15 to move upward along the internal hexagonal cylindrical head screw 11. When the upper surface of the lifting sliding block 15 coincides with the lower surface of the left lifting clamp 13, it drives it to move upward, and then drives the knee control rod 17 to move upward and push the knee control lifting lever 18 to rotate, finally lifting the presser foot in the presser foot assembly 19;

[0044] 4) When sewing needs to be started again, the presser foot falls down. At this time, the stepper motor 1 rotates forward, and the lifting cam 8 rotates to drive the lifting cam rod 9 to move, thereby driving the lifting sliding block 15 to move downward along the internal hexagonal cylindrical head screw 11. The lifting sliding block 15 and the left lifting clamp 13 separate, and the presser foot in the presser foot assembly 19 falls down. At the same time, the cylindrical head of the stitch pitch drive wheel 2 engages with the "U" groove 22 on the stitch pitch driven wheel 3.

[0045] 5) Steps 1), 2), 3) and 4) constitute a complete motion process. Repeating steps 1)-4) will allow you to control the stitch length and lift the presser foot.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention.

Claims

1. Method of operation of a mechanism for simultaneously controlling the stitch length and the lifting of the presser foot by a stepper motor, characterized in that: The working method is: 1) the machine works normally, the presser foot is lowered, the stepping motor (1) rotates forward to drive the needle spacing driving wheel (2) to rotate, the cylindrical head (20) of the needle spacing driving wheel (2) is matched with the "U"-shaped groove (22) on the needle spacing driven wheel (3), the needle spacing driven wheel (3) is rotated by the needle spacing driving wheel (2) every time the needle spacing driving wheel (2) is rotated by a corresponding angle, at the same time, the needle spacing cam connecting rod (5) is matched with the needle spacing adjusting frame (7) to rotate by a certain angle to realize the adjustment of the size of the needle spacing; 2) during the adjustment of the size of the needle spacing, the lifting and pressing cam rod (9) drives the lifting and pressing sliding block (15) to move, the lifting and pressing sliding block (15) is always lower than the fixed position of the left lifting clamp block (13) at the highest position of the inner hexagonal cylindrical head screw (11) when the presser foot is lowered, so the presser foot is always attached to the needle plate during this process; 3) when the presser foot needs to be lifted, the stepping motor (1) starts to reverse, the cylindrical head of the needle spacing driving wheel (2) is separated from the "U"-shaped groove on the needle spacing driven wheel (3), at the same time, the arc surface of the arc-shaped notch (21) of the needle spacing driving wheel (2) is engaged with the arc surface of the needle spacing driven wheel (3), the relative position of the needle spacing driven wheel (3) is limited, when the needle spacing driving wheel (2) continues to rotate, the needle spacing driven wheel (3) is relatively static, at this time, the lifting and pressing cam (8) rotates to drive the lifting and pressing cam rod (9) to move, so as to drive the lifting and pressing sliding block (15) to move upward along the inner hexagonal cylindrical head screw (11), when the upper surface of the lifting and pressing sliding block (15) and the lower surface of the left lifting clamp block (13) coincide, the left lifting clamp block (13) is driven to move upward, then the knee control rod (17) is driven to move upward to push the knee control lifting lever (18) to rotate, finally the presser foot in the presser foot assembly (19) is lifted; 4) when the sewing needs to start again, the presser foot is lowered, at this time, the stepping motor (1) rotates forward, the lifting and pressing cam (8) rotates to drive the lifting and pressing cam rod (9) to move, so as to drive the lifting and pressing sliding block (15) to move downward along the inner hexagonal cylindrical head screw (11), the lifting and pressing sliding block (15) is separated from the left lifting clamp block (13), the presser foot in the presser foot assembly (19) is lowered, at the same time, the cylindrical head of the needle spacing driving wheel (2) is matched with the "U"-shaped groove (22) on the needle spacing driven wheel (3); 5) steps 1), 2), 3) and 4) are a complete movement process, after that, steps 1)-4) are repeated to realize the control of the needle spacing and the lifting of the presser foot; The mechanism for controlling the needle spacing and the lifting of the presser foot by the stepping motor simultaneously comprises a stepping motor (1), a knee control rod (17), a knee control lifting lever (18) and a presser foot assembly (19), the upper part of the knee control rod (17) is fixedly connected with the knee control lifting lever (18), the knee control lifting lever (18) is connected with the knee control connecting rod left ear of the presser foot assembly (19) to realize the up-down movement of the presser foot assembly (19); the output shaft of the stepping motor (1) is sequentially sleeved with a needle spacing driving wheel (2), a lifting and pressing cam (8) and a lifting and pressing cam cover plate (10). The middle part of the knee lever (17) is fastened by the left lifting clamp block (13) and the right lifting clamp block (14), the bottom of the left lifting clamp block (13) is movably connected with the lifting pressing sliding block (15) through the inner hexagonal cylindrical head screw (11), the lifting pressing sliding block (15) slides up and down along the inner hexagonal cylindrical head screw (11), the structure of the lifting pressing cam lever (9) comprises a Z-shaped rod integrally arranged on a ring, the lifting pressing cam cover plate (10) is fixed on the ring of the lifting pressing cam lever (9), the upper end of the Z-shaped rod of the lifting pressing cam lever (9) is clamped in the U-shaped groove of the lifting pressing sliding block (15), and the lifting pressing sliding block (15) is driven to move up and down by the rotation of the lifting pressing cam lever (9); The needle pitch cam shaft (4) is arranged in parallel with the output shaft of the stepping motor (1), the needle pitch driven wheel (3) is fixed on the needle pitch cam shaft (4) and cooperates with the needle pitch driving wheel (2); one end of the needle pitch cam connecting rod (5) is fixed on the needle pitch driven wheel (3), and the other end is fixed on one side of the needle pitch adjusting frame (7); The structure of the needle pitch driving wheel (2) is circular, the circular shape is provided with an arc-shaped notch (21), and the end of the arc-shaped notch is provided with a cylindrical head (20) for driving; the needle pitch driven wheel (3) is provided with a "U"-shaped groove (22) matched with the cylindrical head (20) and an arc surface (23) matched with the arc-shaped notch; The lifting pressing cam (8) and the lifting pressing cam cover plate (10) are provided with one large circular hole and two small circular holes corresponding in position; the lifting pressing cam (8) and the lifting pressing cam cover plate (10) are connected to the output shaft of the stepping motor (1) through the large circular hole and are fixed through the two small circular holes; One side of the lifting pressing sliding block (15) is provided with a U-shaped groove, and the other side is provided with holes from top to bottom for penetrating the inner hexagonal cylindrical head screw (11); the middle positions of the two side faces of the U-shaped groove are provided with pin holes, and a pin shaft (12) is penetrated in the pin holes and is fixed by an E-shaped clamp spring (16) after penetrating the pin holes; The opposite faces of the left lifting clamp block (13) and the right lifting clamp block (14) are respectively provided with column-shaped arc faces, and the column-shaped arc faces are fixed to the knee lever (17).

2. The method of operating the mechanism for simultaneously controlling the stitch length and the presser foot lifting by the stepper motor according to claim 1, characterized in that: The needle pitch cam connecting rod (5) is a "Z"-shaped rod, and the two ends are respectively fixed to the needle pitch driven wheel (3) and the needle pitch adjusting frame (7) through shaft position screws (6).

3. The method of operating a mechanism for simultaneously controlling stitch length and presser foot lift by a stepper motor according to claim 1 or 2, characterized in that: The lifting pressing cam (8) is provided with a step, and the step is clamped at the ring of the lifting pressing cam lever (9).

4. The method of operating the mechanism for simultaneously controlling the stitch length and the presser foot lifting by the stepper motor according to claim 3, characterized in that: The left lifting clamp block (13) is provided with a threaded through hole from top to bottom, and the inner hexagonal cylindrical head screw (11) is fixed in the through hole of the left lifting clamp block (13).

5. The method of operating the mechanism for simultaneously controlling the stitch length and the presser foot lifting by the stepper motor according to claim 4, characterized in that: The needle pitch cam shaft (4) is fixed on the machine shell.

Images