Sewing path capable of improving stretch rate, lockstitch sewing machine, and sewing process based on lockstitch sewing machine

Abstract

A sewing path capable of improving the stretch rate, which is applied to the sewing process of a lockstitch sewing machine. The lockstitch sewing machine comprises a feed dog (9), a dog carrier (14), a feed electric motor (5), a feed transmission mechanism (6), a dog-lifting electric motor (7), a dog-lifting transmission mechanism (8), a spindle electric motor (1), a spindle (2), a spindle transmission mechanism (3), a sewing needle (4), and a control system, wherein the feed dog (9) is arranged on the dog carrier (14), and the feed electric motor (5) is connected to the dog carrier (14) by means of the feed transmission mechanism (6) and is configured to drive the dog carrier (14) to move back and forth; the dog-lifting electric motor (7) is connected to the dog carrier (14) by means of the dog-lifting transmission mechanism (8) and is configured to drive the dog carrier (14) to move up and down; and the spindle electric motor (1) drives, by means of the spindle (2) and the spindle transmission mechanism (3), the sewing needle (4) to move up and down. Further provided are a lockstitch sewing machine, and a sewing process based on a lockstitch sewing machine. By means of the coordinated movement of the spindle electric motor, the dog-lifting electric motor and the feed electric motor, a new movement path is realized, thereby achieving a higher stretch rate, and effectively broadening the adaptability to different types of sewing materials.

Description

A sewing trajectory for improving stretchability, a flatbed sewing machine, and a flatbed sewing machine sewing process. Technical Field

[0001] This invention relates to the field of elastic fabric sewing equipment technology, and in particular to a sewing trajectory that improves the stretch rate, a flatbed sewing machine, and a flatbed sewing machine sewing process. Background Technology

[0002] The use of elastic seam fabric is becoming increasingly common in the market. After sewing, elastic seam fabric not only needs to maintain a normal stitch, but also needs to be able to stretch a longer distance (referred to as elongation) without the bottom and top threads breaking. Current flatbed sewing machines, without external force, cannot meet the maximum elongation requirement of elastic seam fabric without thread breakage. Operators need to pre-stretch the elastic fabric before sewing. This not only increases the difficulty of sewing but also makes it difficult to ensure that the elongation is uniform.

[0003] The reasons for the low elongation of existing elastic seam materials are as follows:

[0004] Figure 1 shows a schematic diagram of the lockstitch pattern formed by the elastic fabric 11 through a flat sewing machine. The lockstitch consists of two threads (bottom thread 13 and top thread 12) interlaced within the elastic fabric 11. The upper and lower ends of the elastic fabric 11 have the same shape, resulting in a tighter seam. The straight lockstitch is the most commonly used stitch. Due to the tight seam, the amount of top thread incorporated within one stitch length L is m1 + m2 + m3, and the amount of bottom thread is d1 + d2 + d3. m2 is located on the upper surface 1101 of the elastic fabric, and d2 is located on the lower surface 1102. Because the amount of bottom thread 13 and top thread 12 used is relatively small, their tensile strength and elasticity are relatively poor. When the bottom thread 13 or top thread 12 is sewn with non-elastic cotton thread to sew the elastic fabric 11, the low elongation of the bottom thread 13 and top thread 12 limits the elongation of the overall fabric after sewing, reducing the sewing effect; if the elastic fabric 11 is stretched too hard, the lockstrap track may break.

[0005] To address the problems in the existing technology, as shown in Figures 2 and 3, the operator needs to pre-stretch the elastic fabric 11 before sewing. When the elastic fabric 11 is stretched for sewing, the set stitch length L1 must be greater than L. This ensures that the elastic fabric 11 shrinks after sewing, and the stitch length returns to L. The lockstitch formed when stretching the elastic fabric is shown in Figure 2. Taking the top thread 12 as an example, the length of the top thread 12 in the elastic fabric 11 remains basically unchanged, that is, m1 and m3. However, since the stitch length L1 is greater than L, the amount of top thread m4 integrated into the upper surface of the elastic fabric 11 within one stitch length L1 is greater than m2. Correspondingly, the amount of bottom thread d4 integrated within one stitch length L1 is greater than d2. After sewing is completed, as shown in Figure 3, the elastic fabric 11 is de-stretched. The stretched elastic fabric 11 will shrink due to its own rebound. At this time, the stitch length on the elastic fabric 11 changes from L1 back to L, and the stitch length decreases. Since the bobbin thread 13 and the top thread 12 are inelastic, the lengths of the top thread 12 and bobbin thread 13 incorporated in one stitch length remain unchanged at m4 and d4, respectively. Compared with the amount of top thread m1+m2+m3 and bobbin thread d1+d2+d3 incorporated in the stitch length L in Figure 1, the amount of top thread m1+m4+m3 and bobbin thread d1+d4+d3 incorporated in the stitch length L in Figures 2 and 3 is greater, so the stretching rate is also greater.

[0006] As mentioned above, pre-stretching the elastic fabric before sewing can ensure the stretch rate of the elastic fabric after sewing, but it will increase the sewing difficulty for the operator and make it difficult to guarantee the same stretch rate.

[0007] Therefore, it is necessary to design a sewing trajectory, flatbed sewing machine, and flatbed sewing process that improves the stretch rate. When sewing elastic fabric, the elastic fabric can be stretched to ensure that when the elastic fabric shrinks to the predetermined stitch length after sewing, more top and bottom threads are incorporated, thereby improving the stretch rate of the elastic fabric. Summary of the Invention

[0008] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a sewing track, a flat sewing machine, and a flat sewing machine sewing process that improves the stretch rate, in order to solve the problem that in the prior art, sewing elastic fabric requires the operator to pre-stretch the elastic fabric, which increases the sewing difficulty for the operator and makes it difficult to ensure the same stretch rate.

[0009] To achieve the above and other related objectives, this invention provides a sewing trajectory that improves stretchability, applied in the sewing process of a flatbed sewing machine. The flatbed sewing machine includes a feed dog, a feed dog holder, a feed motor, a feed transmission mechanism, a lifter motor, a lifter transmission mechanism, a main shaft motor, a main shaft, a main shaft transmission mechanism, a needle, and a control system. The feed dog is mounted on the feed dog holder. The feed motor is connected to the feed dog holder via the feed transmission mechanism and drives the feed dog holder to move back and forth. The lifter motor is connected to the feed dog holder via the lifter transmission mechanism and drives the feed dog holder to move up and down. The main shaft motor drives the needle to move up and down via the main shaft and the main shaft transmission mechanism. The control system is connected to the feed motor, the lifter motor, and the main shaft motor. The control system adjusts the swing angle of the feed motor and the lifter motor relative to the main shaft. The feed motor and the lifter motor cooperate to form the movement trajectory of the feed dog, which stretches the elastic fabric as it moves along the trajectory.

[0010] Preferably, the movement trajectory of the feed dog includes an initial position, a feed dog protruding from the needle plate position, a feed dog at its highest point, and a feed dog returning to a position flush with the needle plate. With the cooperation of the lifting motor and the feeding motor, the feed dog moves sequentially from the initial position to the feed dog protruding from the needle plate position, the feed dog at its highest point, and then back to the position flush with the needle plate, finally returning to the initial position, completing one feed dog movement cycle. The feed dog does not contact the elastic fabric during its movement from the initial position to the feed dog protruding from the needle plate position. During its movement from the feed dog protruding from the needle plate position through the feed dog at its highest point to its return to the position flush with the needle plate, the elastic fabric is first stretched, and then transported. The feed dog does not contact the elastic fabric during its return from the position flush with the needle plate to the initial position.

[0011] Preferably, the distance the feed tooth moves horizontally from its initial position to the position where the feed tooth protrudes from the needle plate is not less than 0.1 times the distance the feed tooth moves horizontally from its initial position to the position where the feed tooth falls back to the level position with the needle plate.

[0012] Preferably, the teeth at both ends of the feed tooth are the first tooth and the last tooth, respectively; when the feed tooth moves from the initial position to the position where the feed tooth protrudes from the needle plate, the first tooth protrudes from the needle plate first and contacts the elastic fabric, and the last tooth protrudes from the needle plate last and contacts the elastic fabric.

[0013] Preferably, during the time from the first tooth protruding from the pin plate to the last tooth protruding from the pin plate, the horizontal height of the first tooth is greater than the horizontal height of the last tooth.

[0014] Preferably, during the time from the first tooth protruding from the needle plate to the last tooth protruding from the needle plate, the distance the first tooth moves in the horizontal direction is not less than 0.1 times the needle distance.

[0015] To achieve the above or other objectives, the present invention also discloses a flat sewing machine that operates according to the above-described sewing trajectory that increases the elongation rate, thereby sewing elastic fabric.

[0016] To achieve the above or other objectives, the present invention also discloses a sewing process using a flatbed sewing machine, which is used to sew elastic fabric; the steps are as follows:

[0017] S1: Place the elastic fabric onto the needle plate of the flat sewing machine and input the sewing trajectory parameters of the elastic fabric through the control system;

[0018] S2: The control system acquires the spindle angle;

[0019] S3: The control system determines the swing angle of the feed motor and the lifting motor relative to the main shaft based on the sewing trajectory parameters of the elastic fabric input in step S1.

[0020] S4: The control system starts the feeding motor and the lifting motor to rotate the corresponding swing angle.

[0021] S5: The control system acquires the angle of the main shaft in real time. When the angle of the main shaft changes, repeat steps S2-S4 to adjust the swing angle between the feeding motor, the lifting motor and the main shaft in real time so that the movement trajectory of the feeding teeth and the main shaft conforms to the sewing trajectory of the elastic fabric, and completes the sewing of the elastic fabric by the flat sewing machine.

[0022] Preferably, in step S5, when the angle of the main shaft changes, the flat sewing machine is in normal sewing state, and the swing angle between the feed motor, the lifting motor and the main shaft changes in real time; when the angle of the main shaft does not change, the flat sewing machine is in a stopped state.

[0023] As described above, the sewing track for improving elongation, the flatbed sewing machine, and the flatbed sewing machine sewing process of the present invention have the following beneficial effects:

[0024] This invention relates to a sewing trajectory for improving stretchability, a flatbed sewing machine, and a flatbed sewing machine sewing process. Through the coordinated movement of the main shaft motor, the feed motor, and the feed motor, a novel motion trajectory is achieved. Compared to the conventional elliptical trajectory, this trajectory achieves a higher stretchability when sewing elastic fabrics, effectively broadening its adaptability to different types of fabrics. The mechanical structure of the flatbed sewing machine remains unchanged; only the control logic in the control system is modified to adapt to different types of fabrics. This solves the problem in existing technologies where operators need to stretch the elastic fabric when sewing, which increases the difficulty of sewing and results in uneven stretchability due to manual stretching. Attached Figure Description

[0025] Figure 1 is a schematic diagram of the operation of elastic seam material when sewing without stretching in the prior art of the present invention;

[0026] Figure 2 is a schematic diagram of the operation of elastic sewing material during stretching and sewing in the prior art of the present invention;

[0027] Figure 3 is a schematic diagram of the shrinkage of elastic sewing material after sewing in the prior art of the present invention;

[0028] Figure 4 is a partial structural schematic diagram of the flat sewing machine in this invention;

[0029] Figure 5 is a schematic diagram of the start of stretching of the elastic fabric by the feed dog in the sewing trajectory of the present invention to improve the stretch rate.

[0030] Figure 6 is a schematic diagram of the end of the stretching of the elastic fabric by the feed dog in the sewing trajectory of the present invention to improve the stretch rate.

[0031] Figure 7 is a schematic diagram showing that the feed dog moves obliquely upward when stretching the elastic fabric in the sewing trajectory of the present invention to improve the stretch rate.

[0032] Figure 8 shows one embodiment of the sewing trajectory for improving elongation according to the present invention;

[0033] Figure 9 is a schematic diagram of the process of sewing elastic fabric using a flat sewing machine according to the present invention.

[0034] Explanation of reference numerals in the attached diagram: 1. Main spindle motor; 2. Main spindle; 3. Main spindle transmission mechanism; 4. Needle; 5. Feed motor; 6. Feed transmission mechanism; 7. Tooth lifting motor; 8. Tooth lifting transmission mechanism; 9. Feed tooth; 901. First tooth; 902. Last tooth; 10. Needle plate; 11. Elastic fabric; 1101. Upper surface of elastic fabric; 1102. Lower surface of elastic fabric; 12. Top thread; 13. Bottom thread; 14. Tooth frame. Detailed Implementation

[0035] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0036] It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings of this specification are merely for illustrative purposes to aid those skilled in the art and are not intended to limit the scope of the invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed in this invention. Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0037] As shown in Figures 1-3 and 4-9, the present invention provides a sewing trajectory that improves the stretch rate, which is applied to the sewing process of a flat sewing machine. The flat sewing machine includes a feed dog 9, a feed dog frame 14, a feed motor 5, a feed transmission mechanism 6, a lifting feed dog motor 7, a lifting feed dog transmission mechanism 8, a main shaft motor 1, a main shaft 2, a main shaft transmission mechanism 3, a needle 4, and a control system. The feed dog 9 is set on the feed dog frame 14, and the feed motor 5 is connected to the feed dog frame 14 through the feed transmission mechanism 6 to drive the feed dog frame 14 to move back and forth. The lifting tooth motor 7 is connected to the tooth frame 14 through the lifting tooth transmission mechanism 8, and is used to drive the tooth frame 14 to move up and down; the main shaft motor 1 drives the needle 4 to move up and down through the main shaft 2 and the main shaft transmission mechanism 3; the control system is connected to the feeding motor 5, the lifting tooth motor 7, and the main shaft motor 1. The control system adjusts the swing angle of the feeding motor 5 and the lifting tooth motor 7 relative to the main shaft 2. The feeding motor 5 and the lifting tooth motor 7 cooperate to form the movement trajectory of the feeding tooth 9. When the feeding tooth 9 moves according to the movement trajectory, it stretches the elastic sewing material 11.

[0038] The sewing trajectory for improving elongation involved in this invention includes a feed motor 5, a tooth-lifting motor 7, a spindle motor 1, and a control system. Each of the feed motor 5, tooth-lifting motor 7, and spindle motor 1 is individually controlled by the control system. This allows for customization of the drive patterns of the feed motor 5 and tooth-lifting motor 7, meaning the running trajectory of the feed tooth 9 can be freely customized. Therefore, by modifying the swing angle motion of the feed motor 5 and tooth-lifting motor 7 through the control system, the speed and direction of the feed tooth 9 when protruding from the needle plate 10 are changed. Combined with the rotation angle of the spindle motor 1, this achieves the effect of the feed tooth 9 stretching the elastic fabric 11 during sewing, ensuring that the elastic fabric 11 has a high elongation rate after sewing.

[0039] Preferably, as shown in Figure 8, the movement trajectory of the feed tooth 9 includes an initial position, a position where the feed tooth 9 protrudes from the needle plate 10, a position where the feed tooth 9 reaches its highest point, and a position where the feed tooth 9 returns to the level with the needle plate 10. With the cooperation of the tooth lifting motor 7 and the feed motor 5, the feed tooth 9 moves sequentially from the initial position to the position where it protrudes from the needle plate 10, to the position where it reaches its highest point, to the position where it returns to the level with the needle plate 10, and finally returns to the initial position from the position where it returns to the level with the needle plate 10. The feed tooth 9 completes one cycle of movement. During its movement from the initial position to the position where it protrudes from the needle plate 10, the feed tooth 9 does not contact the elastic fabric 11. During its movement from the position protruding from the needle plate 10, through its highest point, to its return to the position flush with the needle plate 10, the feed tooth 9 first stretches the elastic fabric 11, then transports it. During its return from the position flush with the needle plate 10 to its initial position, the feed tooth 9 does not contact the elastic fabric 11. In this embodiment, the initial position is point A in Figure 8, the position where the feed tooth 9 protrudes from the needle plate 10 is point B in Figure 8, the highest point of the feed tooth 9 is point C in Figure 8, and the position where the feed tooth 9 returns to the position flush with the needle plate 10 is point D in Figure 8.

[0040] As shown in Figure 8, in this embodiment, the movement trajectory of the feed tooth 9 presents a triangular shape. The three corners of the triangle are not sharp angles but rounded transitions, making the feed tooth 9 run more smoothly along the trajectory and effectively reducing the difficulty of electronic control. To better understand the movement trajectory of the feed tooth 9, a detailed description of the movement trajectory of the feed tooth 9 is provided below:

[0041] Phase 1: Point A → Point B. Point A is the inflection point in the horizontal direction of movement, therefore its horizontal velocity at point A is 0. During the movement from point A to point B, the feed motor 5 and the lifting motor 7 are activated. The feed tooth 9 moves to the left and simultaneously moves upwards. When the feed tooth 9 reaches point B, its teeth just protrude from the needle plate 10 and contact the elastic fabric 11. Since the feed tooth 9 remains below the needle plate 10 throughout its movement from point A to point B, it does not contact the elastic fabric 11 and therefore does not participate in feeding. During the movement from point A to point B, the feed tooth 9 moves a distance S1 to the left in the horizontal direction.

[0042] The second stage: point B → point C. The period between point B and point C is further divided into the stretching of the elastic material (stage 11) and the transportation of the elastic material (stage 11).

[0043] The stretching of the elastic fabric 11 stage is as follows: When the feed tooth 9 reaches point B, the teeth of the feed tooth 9 just protrude from the needle plate 10 and contact the elastic fabric 11. The control system controls the tooth lifting motor 7 and the feed motor 5 to deflect the corresponding swing angle. As shown in Figure 5, the feed tooth 9 is pushed out of the needle plate 10 to the left in an upward-sloping state with the left side higher than the right side. That is, the first tooth 901 at the left end of the feed tooth 9 contacts the elastic fabric 11 first. Since the feed tooth 9 has a horizontal leftward velocity, the horizontal velocity of the elastic fabric 11 at the first tooth 901 is greater than the horizontal velocity of the elastic fabric 11 at the last tooth 902. The first tooth 901 will push the elastic fabric 11 to the left. The feed tooth 9 continues to move, and the second tooth, the third tooth, and so on, gradually contact the elastic material 11. When the last tooth 902 on the right end of the feed tooth 9 contacts the elastic material 11 (as shown in Figure 6), the horizontal velocity of the elastic material 11 at the first tooth 901 is the same as the horizontal velocity of the elastic material 11 at the last tooth 902, and the elastic material 11 will stop stretching. That is, the stretching phase of the elastic material 11 lasts from the moment the first tooth 901 contacts the elastic material 11 until the moment the last tooth 902 contacts the elastic material 11; the length of stretching of the elastic material 11 is proportional to the speed of the feed tooth 9 moving to the left.

[0044] The process of conveying the elastic seam material 11 is as follows: When the last tooth 902 of the feed tooth 9 contacts the elastic seam material 11, the feed tooth 9 drives the elastic seam material 11 to move to the left and upward, thereby conveying the elastic seam material 11.

[0045] Phase 3: Point C → Point D. When feed tooth 9 reaches point C, it begins to decelerate and move downwards. When feed tooth 9 descends to point D, it stops conveying the elastic fabric 11. Therefore, during the process from point C to point D, feed tooth 9 will still convey the elastic fabric 11, but it will decelerate and move downwards. During the entire feeding cycle, the horizontal distance moved by feed tooth 9 is S2, that is, the horizontal distance from point A to point D is S2.

[0046] Phase 4: Point D → Point A. When the feed tooth 9 descends to point D, that is, when the feed tooth 9 disengages from the elastic fabric 11, the feed tooth 9 does not participate in feeding the fabric when it returns from point D to point A. Therefore, during the process from point D to point A, the deflection angle and running speed of the feed tooth 9 do not affect the stretching and transportation of the elastic fabric 11. It is only necessary to ensure that the feed tooth 9 can return to point A and that its horizontal speed is 0 at the corner of point A.

[0047] Preferably, as shown in Figure 8, the distance the feed tooth 9 moves horizontally from its initial position to the position where the feed tooth 9 protrudes from the needle plate 10 is not less than 0.1 times the distance the feed tooth 9 moves horizontally from its initial position to the position where the feed tooth 9 falls back to the position flush with the needle plate 10.

[0048] In this embodiment, the horizontal distance traveled by the feed tooth 9 from its initial position to the position where it protrudes from the needle plate 10 is the horizontal displacement S1 from point A to point B; the horizontal distance traveled by the feed tooth 9 from its initial position to its position where it returns to the level with the needle plate 10 is the horizontal displacement S2 from point A to point D. That is, S1 ≥ 0.1 * S2. The purpose of setting S1 ≥ 0.1 * S2 is that, since the feed tooth 9 has sufficient speed at point B and its speed at point A is 0, meaning that the feed tooth 9 needs to accelerate between points A and B, a certain distance needs to be left so that the feed tooth 9 can accelerate slowly with a low acceleration to reduce the difficulty of electronic control, thus avoiding sudden starts and stops.

[0049] Preferably, as shown in Figures 5-7, the tooth at the left end of the feed tooth 9 is the first tooth 901, and the tooth at the right end is the last tooth 902; when the feed tooth 9 moves from the initial position to the position where the feed tooth 9 protrudes from the needle plate 10, the first tooth 901 protrudes from the needle plate 10 first and contacts the elastic sewing material 11, and the last tooth 902 protrudes from the needle plate 10 last and contacts the elastic sewing material 11.

[0050] In this embodiment, when the first tooth 901 protrudes from the needle plate 10 and contacts the elastic fabric 11, the first tooth 901 has a horizontal velocity to the left. Therefore, the elastic fabric 11 at the first tooth 901 has a horizontal velocity to the left compared to the elastic fabric 11 on the right side, and the elastic fabric 11 is stretched to the left until the last tooth 902 contacts the elastic fabric 11, at which point the stretching of the elastic fabric 11 stops. At this time, the elastic fabric 11 at the first tooth 901 and the elastic fabric 11 at the last tooth 902 have the same horizontal velocity to the left. Therefore, to ensure that the elastic fabric 11 can be stretched, the horizontal height of the first tooth 901 is greater than the horizontal height of the last tooth 902 during the time from when the first tooth 901 protrudes from the needle plate 10 to when the last tooth 902 protrudes from the needle plate 10. That is, the feed tooth 9 runs in an upward sloping state with the left side higher than the right side when it protrudes from the needle plate 10 at point B.

[0051] The feed tooth 9 protrudes from point B onto the needle plate 10 in an upward sloping direction, higher on the left and lower on the right, as shown in Figure 7. The distance between the first tooth 901 and the horizontal reference plane is H1, and the distance between the last tooth 902 and the horizontal reference plane is H2. During the stretching of the elastic sewing material 11, H1 must always be greater than H2. The horizontal reference plane can be set to a horizontal plane 50mm away from the upper surface of the needle plate 10. The angle between the top surface of the feed tooth 9 and the horizontal plane is β (counterclockwise is positive; a positive value indicates the top surface of the tooth is sloping downwards, and a negative value indicates the top surface of the tooth is sloping upwards). The left end of the feed tooth 9 is connected to the feed motor 5 as the feed end, and the right end of the feed tooth 9 is connected to the lifting motor 7 as the lifting end. The feed tooth 9 protrudes from the needle plate 10 in an upward sloping direction, higher on the left and lower on the right, meaning the feed end is higher than the lifting end.

[0052] Preferably, as shown in Figures 1-3, 5, and 6, the distance the first tooth 901 moves horizontally from the time the first tooth 901 protrudes from the needle plate 10 to the time the last tooth 902 protrudes from the needle plate 10 is not less than 0.1 times the stitch pitch. In this embodiment, the time interval from the time the first tooth 901 protrudes from the needle plate 10 to the time the last tooth 902 protrudes from the needle plate 10 is T, and the distance the first tooth 901 moves horizontally is a, that is, a needs to be not less than 0.1 times the stitch pitch; the purpose is that when a is less than 0.1 times the stitch pitch, the length of the elastic sewing material 11 stretched by the feed tooth 9 is insufficient. When the elastic sewing material 11 shrinks, the length of the top thread 12 and the bottom thread 13 integrated into the elastic sewing material 11 is short, and the stretching rate does not meet the requirements.

[0053] To achieve the above or other objectives, the present invention also discloses a flat sewing machine that operates according to the above-described sewing trajectory for increasing the elongation rate, thereby sewing the elastic fabric 11.

[0054] To achieve the above or other objectives, as shown in Figure 9, the present invention also discloses a sewing process using a flatbed sewing machine, which is used to sew the elastic fabric 11; the steps are as follows:

[0055] S1: Place the elastic sewing material 11 onto the needle plate 10 of the flat sewing machine, and input the sewing trajectory parameters of the elastic sewing material 11 through the control system;

[0056] S2: The control system acquires the angle of spindle 2;

[0057] S3: The control system determines the swing angle of the feed motor 5 and the lifting motor 7 relative to the main shaft 2 based on the sewing trajectory parameters of the elastic sewing material 11 input in step S1.

[0058] S4: The control system starts the feeding motor 5 and the tooth lifting motor 7 to rotate the corresponding swing angle.

[0059] S5: The control system acquires the angle of the main shaft 2 in real time. When the angle of the main shaft 2 changes, repeat steps S2-S4 to adjust the swing angle between the feeding motor 5, the lifting tooth motor 7 and the main shaft 2 in real time so that the movement trajectory of the feeding tooth 9 and the main shaft 2 conforms to the sewing trajectory of the elastic fabric 11, and completes the sewing of the elastic fabric 11 by the flat sewing machine.

[0060] Preferably, in step S1, the sewing trajectory parameters of the elastic sewing material 11 include the stitch length L1, the horizontal distance S1 from point A to point B, the horizontal distance S2 from point A to point D, the time interval T between the first tooth 901 protruding from the needle plate 10 and the last tooth 902 protruding from the needle plate 10, and the distance a that the first tooth 901 moves horizontally within time T, etc. All of the above parameters can be adjusted by the control system by adjusting the feeding motor 5, the tooth lifting motor 7, and the spindle motor 1.

[0061] Preferably, in step S2, the angle of the spindle 2 can be acquired in real time by a sensor, and the sensor feeds back the angle of the spindle 2 to the control system. The acquisition of the spindle 2 angle is existing technology and will not be described again here.

[0062] Preferably, in step S5, when the angle of the main shaft 2 changes, the flat sewing machine is in normal sewing state, and the swing angle between the feed motor 5, the tooth lifting motor 7 and the main shaft 2 changes in real time; when the angle of the main shaft 2 does not change, the flat sewing machine is in a stopped state.

[0063] The present invention relates to a sewing trajectory for improving stretch rate, a flatbed sewing machine, and a flatbed sewing machine sewing process. Through the coordinated movement of the main shaft motor 1, the lifting tooth motor 7, and the feeding motor 5, a novel motion trajectory is achieved. Compared with the conventional elliptical trajectory, when sewing elastic fabric 11, a higher stretch rate can be achieved, which can effectively broaden the adaptability to different types of fabrics and further enhance the competitiveness of the product. It solves the problem in the prior art that when sewing elastic fabric 11, the operator needs to pull the elastic fabric 11 apart, which increases the sewing difficulty for the operator and results in uneven stretch rate when manually stretching the elastic fabric 11.

[0064] Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0065] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A sewing trajectory with improved stretch rate, applied in the sewing process of a flat sewing machine; the flat sewing machine includes a feed dog (9), a feed dog holder (14), a feed motor (5), a feed transmission mechanism (6), a lift-up motor (7), a lift-up transmission mechanism (8), a main shaft motor (1), a main shaft (2), a main shaft transmission mechanism (3), a needle (4), and a control system, wherein the feed dog (9) is mounted on the feed dog holder (14), the feed motor (5) is connected to the feed dog holder (14) through the feed transmission mechanism (6) and is used to drive the feed dog holder (14) to move back and forth; the lift-up motor (7) is connected to the feed dog holder (14) through the lift-up transmission mechanism (8) and is used to drive the feed dog holder (14) to move up and down; the main shaft motor (1) drives the needle (4) to move up and down through the main shaft (2) and the main shaft transmission mechanism (3); characterized in that: The control system is connected to the feeding motor (5), the lifting motor (7), and the main shaft motor (1). The control system adjusts the swing angle of the feeding motor (5) and the lifting motor (7) relative to the main shaft (2). The feeding motor (5) and the lifting motor (7) cooperate to form the motion trajectory of the feeding tooth (9). When the feeding tooth (9) moves according to the motion trajectory, it stretches the elastic sewing material (11).

2. The sewing trajectory for improving elongation according to claim 1, characterized in that: The movement trajectory of the feed tooth (9) includes the initial position, the position where the feed tooth (9) protrudes from the needle plate (10), the highest point of the feed tooth (9), and the position where the feed tooth (9) falls back to the level of the needle plate (10). With the cooperation of the tooth lifting motor (7) and the feed motor (5), the feed tooth (9) moves sequentially from the initial position to the position where the feed tooth (9) protrudes from the needle plate (10), the highest point of the feed tooth (9), the position where the feed tooth (9) falls back to the level of the needle plate (10), and finally returns to the initial position from the position where the feed tooth (9) falls back to the level of the needle plate (10), thus completing one feed tooth (9) movement cycle. During the process of the feed tooth (9) moving from the initial position to the position where the feed tooth (9) protrudes from the needle plate (10), it does not contact the elastic fabric (11); during the process of the feed tooth (9) moving from the position where the feed tooth (9) protrudes from the needle plate (10), passing through the highest point of the feed tooth (9), to the position where the feed tooth (9) falls back to the level with the needle plate (10), the elastic fabric (11) is stretched first, and then the elastic fabric (11) is transported. During the process of the feed tooth (9) falling back to the initial position from the feed tooth (9) to the position flush with the needle plate (10), it does not contact the elastic sewing material (11).

3. The sewing trajectory for improving tensile strength according to claim 2, characterized in that: The distance the feed tooth (9) moves horizontally from its initial position to the position where it protrudes from the needle plate (10) is not less than 0.1 times the distance the feed tooth (9) moves horizontally from its initial position to the position where it falls back to the level with the needle plate (10).

4. The sewing trajectory for improving tensile strength according to claim 2, characterized in that: The teeth at both ends of the feed tooth (9) are the first tooth (901) and the last tooth (902), respectively. When the feed tooth (9) moves from the initial position to the position where the feed tooth (9) protrudes from the needle plate (10), the first tooth (901) protrudes from the needle plate (10) first and contacts the elastic fabric (11), and the last tooth (902) protrudes from the needle plate (10) last and contacts the elastic fabric (11).

5. The sewing trajectory for improving tensile strength according to claim 4, characterized in that: During the time from when the first tooth (901) protrudes from the needle plate (10) to when the last tooth (902) protrudes from the needle plate (10), the horizontal height of the first tooth (901) is greater than the horizontal height of the last tooth (902).

6. The sewing trajectory for improving tensile strength according to claim 4, characterized in that: During the time from the first tooth (901) protruding from the needle plate (10) to the last tooth (902) protruding from the needle plate (10), the distance the first tooth (901) moves in the horizontal direction is not less than 0.1 times the needle distance.

7. A flat sewing machine, characterized in that: The flat sewing machine operates according to the sewing trajectory with increased elongation as described in any one of claims 1-6, thereby sewing the elastic fabric (11).

8. A sewing process using a flatbed sewing machine, wherein the flatbed sewing machine as described in claim 7 is used to sew elastic fabric (11); characterized in that: The steps are as follows: S1: Place the elastic fabric (11) onto the needle plate (10) of the flat sewing machine and input the sewing trajectory parameters of the elastic fabric (11) through the control system; S2: The control system acquires the angle of the spindle (2); S3: The control system determines the swing angle of the feed motor (5) and the lifting motor (7) relative to the main shaft (2) based on the sewing trajectory parameters of the elastic sewing material (11) input in step S1. S4: The control system starts the feeding motor (5) and the tooth lifting motor (7) to rotate the corresponding swing angle; S5: The control system acquires the angle of the main shaft (2) in real time. When the angle of the main shaft (2) changes, repeat steps S2-S4 to adjust the swing angle between the feeding motor (5), the lifting motor (7) and the main shaft (2) in real time so that the movement trajectory of the feeding tooth (9) and the main shaft (2) conforms to the sewing trajectory of the elastic fabric (11) and completes the sewing of the elastic fabric (11) by the flat sewing machine.

9. The sewing process of the flat sewing machine according to claim 8, characterized in that: In step S5, when the angle of the main shaft (2) changes, the flat sewing machine is in normal sewing state, and the swing angle between the feed motor (5), the tooth lifting motor (7) and the main shaft (2) changes in real time; when the angle of the main shaft (2) does not change, the flat sewing machine is in a stopped state.

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