Seam starting control method based on presser foot lifting feeding

Abstract

The invention provides a sewing starting control method based on presser foot lifting feeding. The sewing starting control method comprises the following steps that an electric control unit, a presser foot rod, a presser foot and a presser foot lifting mechanism are arranged in a sewing machine; after the sewing material to be sewn is placed, the presser foot is put down, and the electric control unit receives a thick material sewing starting signal; before a feeding tooth sinks downwards into a needle plate during sewing of a first needle, an electric control unit controls a presser foot lifting driving source to act, the presser foot lifting driving source drives a presser foot rod and a presser foot to move upwards through a presser foot lifting transmission unit, the presser foot is lifted to the sewing target height, and the upwarp angle of the presser foot relative to the horizontal plane is reduced; at the moment, the presser foot is still pressed and attached to the sewing starting part of the to-be-sewn sewing material, and the horizontal component force of the pressure applied to the sewing starting part of the to-be-sewn sewing material by the presser foot is not larger than the maximum static friction force between the sewing starting part of the to-be-sewn sewing material and the sewing machine needle plate; in this way, after the feeding teeth sink downwards into the needle plate in the first stitch starting process, the undesirable phenomenon that the sewing starting part of the sewing material to be sewn is pushed away by the presser foot is avoided, and sewing starting material pushing is effectively avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of sewing machines, and particularly to a starting seam control method based on feeding with the presser foot lifted. Background Art

[0002] When a flat sewing machine sews thick materials such as down jackets and cotton-padded clothes, the starting seam process requires that the starting seam point of the thick material be placed in front of the sewing needle, that is, the starting seam part of the thick material sewing needs to be close to directly below the sewing needle. As Figure 1 shown, at this time, the sewing needle is at the upper stop position, and the presser foot is in the lifted state; then, the presser foot is lowered, and the sewing needle moves downward to pierce the material, as Figure 2 shown, and the starting seam sewing begins. However, during this starting seam process, there is an easy occurrence of a starting seam material pushing phenomenon where the sewing material is pushed away from the sewing needle direction when the presser foot is lowered, or the sewing material is pushed away from the sewing needle direction when sewing the first stitch. The starting seam material pushing phenomenon will cause the thick material to not be sewn normally. At this time, the operator needs to manually push the thick material between the presser foot and the needle plate. However, it is impossible to control the strength well when manually pushing the material, which not only increases the operation difficulty but also easily causes broken needles during starting seam. Summary of the Invention

[0003] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a starting seam control method based on feeding with the presser foot lifted to avoid the starting seam material pushing phenomenon.

[0004] To achieve the above purpose, the present invention provides a starting seam control method based on feeding with the presser foot lifted, and the starting seam control method includes the following steps:

[0005] S1. Configure an electronic control unit, a presser foot lever that is supported in the sewing machine housing so as to be movable up and down, a presser foot installed at the lower end of the presser foot lever, and a presser foot lifting mechanism in the sewing machine. The presser foot lifting mechanism includes a presser foot lifting drive source and a presser foot transmission unit. The presser foot lifting drive source is connected to the presser foot lever through the presser foot transmission unit, and the presser foot lifting drive source is communicatively connected to the electronic control unit;

[0006] S2. Place the sewing material to be sewn. At this time, the presser foot is lifted, the sewing needle in the sewing machine is at the upper stop position, and the feed dog in the sewing machine protrudes from the needle plate;

[0007] S3. Place the sewing material to be sewn in place. The starting seam part of the sewing material to be sewn is close to directly below the sewing needle of the sewing machine and the two are distributed successively along the feeding direction of the sewing machine;

[0008] S4. Lower the presser foot, and the electronic control unit receives the thick material starting seam signal;

[0009] S5. Before the feed dog sinks downward into the needle plate at the first stitch of starting sewing, the electronic control unit controls the presser foot lifting drive source to act. The presser foot lifting drive source drives the presser foot bar and the presser foot to move upward through the presser foot transmission unit, lifts the presser foot to the starting sewing target height, and reduces the upward warping angle of the presser foot relative to the horizontal plane. At this time, the presser foot still presses against the starting sewing part of the material to be sewn, and the horizontal component of the pressure exerted by the presser foot on the starting sewing part of the material to be sewn is not greater than the maximum static friction between the starting sewing part of the material to be sewn and the sewing machine needle plate.

[0010] S6. After sewing the set number of stitches at the start of sewing, the electronic control unit controls the presser foot lifting drive source to reset, the presser foot bar and the presser foot move downward, and the presser foot returns to the lowered state.

[0011] S7. The sewing machine continues sewing.

[0012] Further, in step S5, the electronic control unit also obtains the thickness of the starting sewing part of the material to be sewn, and the electronic control unit controls the action amplitude of the presser foot lifting drive source according to the thickness of the starting sewing part of the material to be sewn, so that the starting sewing target height is adapted to the thickness of the starting sewing part of the material to be sewn.

[0013] Further, in step S1, a material thickness detection sensor is also configured in the sewing machine. The material thickness detection sensor is used to detect the thickness of the material under the presser foot, and the material thickness detection sensor is communicatively connected to the electronic control unit.

[0014] In step S5, the electronic control unit obtains the thickness of the starting sewing part of the material to be sewn according to the feedback of the material thickness detection sensor.

[0015] Further, a starting sewing control mapping table is pre-stored in the electronic control unit. The starting sewing control mapping table includes multiple groups of mapping relationships. Each group of mapping relationships includes the thickness of the starting sewing part of the material to be sewn, the starting sewing target height, and the output value of the presser foot lifting drive source that correspond one by one.

[0016] In step S5, after the electronic control unit obtains the thickness of the starting sewing part of the material to be sewn, it controls the action amplitude of the presser foot lifting drive source according to the mapping relationship where the thickness of the starting sewing part of the material to be sewn is located.

[0017] Further, in step S5, when the presser foot is lifted to the starting sewing target height, the upward warping angle of the presser foot relative to the horizontal plane is 0° to 30°.

[0018] Further, the presser foot lifting transmission unit includes a driving cam, a first swing rod having a fixed rotation fulcrum, a driving ball rotatably mounted at one end of the first swing rod, a first connecting rod, a second swing rod having a fixed rotation fulcrum, a second connecting rod, a third swing rod having a fixed rotation fulcrum, a presser foot lifting plate, and a presser foot pressing block fixed to the upper end of the presser foot rod. The driving cam is connected to the presser foot driving source. The driving ball is in contact and cooperation with the outer peripheral surface of the driving cam. Two ends of the first connecting rod are respectively hinged to the other end of the first swing rod and one end of the second swing rod. Two ends of the second connecting rod are respectively hinged to the other end of the second swing rod and one end of the third swing rod. The other end of the third swing rod is hinged to the upper end of the presser foot lifting plate. The presser foot lifting plate is provided with a lifting hook portion. The presser foot pressing block is provided with a connecting protrusion portion. The connecting protrusion portion is engaged with the lifting hook portion.

[0019] Further, the presser foot driving source is a motor.

[0020] As described above, the starting seam control method based on presser foot lifting for feeding in the present invention has the following beneficial effects:

[0021] When starting to sew thick materials in this application, before the feed dog sinks into the needle plate when sewing the first stitch at the start of sewing, the presser foot is lifted to the starting seam target height by controlling the action of the presser foot driving source. The starting seam target height satisfies the following conditions: reducing the upward tilt angle of the presser foot relative to the horizontal plane, the presser foot still pressing against the starting part of the material to be sewn, and the horizontal component force of the pressure exerted by the presser foot on the starting part of the material to be sewn not being greater than the maximum static friction force between the starting part of the material to be sewn and the sewing machine needle plate. In this way, after the feed dog sinks into the needle plate when sewing the first stitch, even without the holding force of the feed dog on the starting part of the material to be sewn, there will be no bad phenomenon that the starting part of the material to be sewn is pushed away by the presser foot, effectively avoiding starting seam material pushing and ensuring normal sewing. Description of the Drawings

[0022] Figure 1 It is a schematic diagram of the placement of the starting part of thick materials on the sewing machine needle plate when starting to sew thick materials.

[0023] Figure 2 It is a schematic diagram of the state of the presser foot pushing the material when starting to sew in the prior art.

[0024] Figure 3 It is a control block diagram of the starting seam control method based on presser foot lifting for feeding in this application.

[0025] Figure 4 It is a connection schematic diagram of the presser foot rod, the presser foot and the presser foot lifting mechanism in this application.

[0026] Figure 5 It is a connection block diagram of the sewing material thickness detection sensor, the presser foot driving source and the electronic control unit in this application.

[0027] Figure 6 Schematic diagram of the movement trajectory of the feed dog in this application.

[0028] Figure 7 Schematic diagram showing that the feed dog does not sink downward into the needle plate when starting to sew the first stitch in this application.

[0029] Figure 8 Schematic diagram after the feed dog sinks downward into the needle plate when starting to sew the first stitch in this application. The feed dog is omitted in this figure.

[0030] Figure 9 It is Figure 8 Force analysis diagram of the presser foot.

[0031] Figure 10 It is Figure 8 Force analysis diagram of the starting sewing part of the sewing material to be sewn.

[0032] Figure 11 Schematic diagram of the starting sewing process of the sewing material to be sewn in this application.

[0033] Figure 12 Control block diagram of the over-bar control method based on lifting the presser foot for feeding in this application.

[0034] Figure 13 Schematic diagram of the state when passing over a bar during sewing.

[0035] Figure 14 It is Figure 13 Schematic diagram of the state of the presser foot on the bar position.

[0036] Figure 15 Force analysis diagram of the presser foot and the bar position of the sewing material to be sewn when passing over a bar during sewing in this application.

[0037] Figure 16 Schematic diagram of the over-bar process of the sewing material to be sewn in this application.

[0038] Description of component numbers

[0039] 10 Presser foot lever

[0040] 20 Presser foot

[0041] 30 Presser foot lifting drive source

[0042] 40 Presser foot lifting transmission unit

[0043] 41 Driving cam

[0044] 42 First swing rod

[0045] 43 Driving ball

[0046] 44 First connecting rod

[0047] 45 The second swing rod

[0048] 46 The second connecting rod

[0049] 47 The third swing rod

[0050] 48 The presser foot lifting plate

[0051] 49 The presser foot pressing block

[0052] 50 The needle plate

[0053] 61 The starting sewing part

[0054] 62 The rib position

[0055] 70 The feed dog Specific embodiments

[0056] The following specific embodiments illustrate the implementation manners 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.

[0057] It should be noted that the structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those skilled in the art to understand and read, and are not used to limit the limited conditions for the implementation of the present invention. Therefore, they do not have technical essence. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of description and are not used to limit the scope for the implementation of the present invention. The change or adjustment of their relative relationships, without substantial change in the technical content, should also be regarded as the scope for the implementation of the present invention.

[0058] It should also be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or it can also be indirectly connected to the other element through an intermediate element.

[0059] In addition, the descriptions involving "first", "second", etc. in this application are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. Additionally, the technical solutions between various embodiments may be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0060] This application provides a sewing machine capable of automatically lifting and lowering the presser foot, and the type of this sewing machine is a flat sewing machine. Based on the characteristic that the sewing machine can automatically lift and lower the presser foot, this application also provides a starting seam control method based on feeding with the presser foot lifted and a crossing control method based on feeding with the presser foot lifted, that is, the sewing machine capable of automatically lifting and lowering the presser foot can be used for starting seam control and crossing control simultaneously.

[0061] As Figure 4 shown, the sewing machine capable of automatically lifting and lowering the presser foot includes a sewing machine housing and a sewing machine table board that are both fixedly arranged, an electronic control unit installed in the sewing machine housing, a presser foot bar 10 that is supported in the sewing machine housing so as to be movable up and down through a bushing, a presser foot 20 installed at the lower end of the presser foot bar 10, and a presser foot lifting mechanism. The presser foot lifting mechanism includes a presser foot driving source 30 and a presser foot transmission unit 40, and the presser foot driving source 30 is connected to the presser foot bar 10 through the presser foot transmission unit 40. When the sewing machine does not lift or lower the presser foot, the presser foot driving source 30 is in an initial state of inaction. At this time, the presser foot 20 is in a lowered state. When the presser foot driving source 30 acts, the presser foot driving source 30 drives the presser foot bar 10 to move upward through the presser foot transmission unit 40, and the presser foot 20 moves upward together with the presser foot bar 10 to achieve automatic lifting of the presser foot. When the output value of the presser foot driving source 30 is different, the distances by which the presser foot bar 10 and the presser foot 20 move upward are different, corresponding to different presser foot lifting heights. In addition, as Figure 5 shown, the presser foot driving source 30 is communicatively connected to the electronic control unit, and the output value of the presser foot driving source 30 is controlled by the electronic control unit.

[0062] Furthermore, a presser foot spring coaxially arranged with the presser foot bar 10 is also configured in the sewing machine. The presser foot spring abuts above the presser foot bar 10 and exerts a downward acting force (i.e., presser foot pressure) on the presser foot bar 10 and the presser foot 20. Thus, after the presser foot 20 is lowered, under the action of the presser foot pressure exerted by the presser foot spring, the presser foot 20 presses against the sewing material.

[0063] As Figure 3 shown, the starting seam control method based on feeding with the presser foot lifted involved in this application successively includes the following steps.

[0064] Step S1. Configure the sewing machine with an automatically liftable presser foot. Then, the sewing machine is at least configured with an electronic control unit, a presser foot lever 10, a presser foot 20, and a presser foot lifting mechanism. In addition, as Figure 7 shown, the sewing machine also has a needle plate 50 fixed to the sewing machine table board, a tooth carrier, a feed dog 70 fixed on the tooth carrier, a feed lifting dog mechanism, a needle bar, a sewing needle installed at the lower end of the needle bar, and a needle bar mechanism. Among them, a tooth groove is provided in the needle plate 50. The feed lifting dog mechanism is connected to the tooth carrier and drives the tooth carrier and the feed dog 70 to perform a combined motion of reciprocating up and down (i.e., vertical motion) and reciprocating back and forth (i.e., horizontal motion). Then, the motion trajectory of the feed dog 70 is an ellipse, as Figure 6 shown; when the feed dog 70 emerges upward from the tooth groove of the needle plate 50, the feed dog 70 contacts the sewing material. Under the action of the feed dog 70, the sewing material is driven to move forward in the horizontal direction. Then, the feeding direction of the sewing machine is the forward direction, that is, the leftward direction facing the left side of the paper surface in the Figure 6 and Figure 7 views. The needle bar mechanism is connected to the needle bar and drives the needle bar and the sewing needle to perform reciprocating up and down motion. Then, the stroke of the sewing needle has a highest point and a lowest point. The highest point of the stroke of the sewing needle is its upper stop position, and the lowest point of the stroke of the sewing needle is its lower stop position.

[0065] S2. Place the sewing material to be sewn. At this time, the presser foot 20 is lifted, the sewing needle in the sewing machine is at the upper stop position, and the feed dog 70 in the sewing machine emerges from the needle plate 50.

[0066] S3. Place the sewing material to be sewn in place. At this time, the presser foot 20 is still in the lifted state. At the same time, the sewing material to be sewn is thick material. According to the starting sewing process requirements of the thick material, the starting sewing part 61 of the sewing material to be sewn needs to be closely adjacent to the rear side directly below the sewing needle of the sewing machine in the front and back direction, as Figure 1 shown. Then, the starting sewing part 61 of the sewing material to be sewn and the sewing needle of the sewing machine are distributed successively in the front and back direction along the feeding direction of the sewing machine. In addition, the starting sewing part 61 of the thick material forms a thick stem head after being folded multiple times. That is, the front end face of the starting sewing part 61 facing the sewing needle is in a shape similar to a circle.

[0067] Step S4. Start sewing, lower the presser foot 20, and the electronic control unit receives the thick material starting sewing signal; the thick material starting sewing signal can be manually input. After the presser foot 20 is lowered, the presser foot 20 presses against the starting sewing part 61 of the sewing material to be sewn, but the sewing needle is at the upper stop position. Based on the linkage relationship between the sewing needle and the feed dog 70, the feed dog 70 is at the Figure 6 A point position of its motion trajectory shown in the figure. Then, at this time, the feed dog 70 is in a state of emerging from the tooth groove of the needle plate 50. Therefore, after placing the sewing material to be sewn and after lowering the presser foot 20, as Figure 7As shown, the feed dog 70 projects upward from the needle plate 50 and acts on the bottom of the starting sewing position 61 of the sewing material to be sewn. The feed dog 70 has a certain fixing effect on the starting sewing position 61 of the sewing material to be sewn, and reliably restricts the sewing material to be sewn from being pushed backward by the presser foot 20.

[0068] Step S5: Before the feed dog 70 sinks downward into the needle plate 50 when sewing the first stitch at the start of sewing, the electronic control unit controls the presser foot driving source 30 to act. The presser foot driving source 30 drives the presser foot lever 10 and the presser foot 20 to move upward through the presser foot transmission unit 40, and raises the presser foot 20 to the target starting sewing height, reducing the upward tilt angle θ of the presser foot 20 relative to the horizontal plane. Therefore, it can be that before starting to sew the first stitch, the electronic control unit has controlled the presser foot driving source 30 to act and has raised the presser foot 20 to the target starting sewing height; or it can be that during the process of the sewing machine needle moving downward when starting to sew the first stitch and before the feed dog 70 sinks downward into the needle plate 50, the electronic control unit controls the presser foot driving source 30 to act and raises the presser foot 20 to the target starting sewing height. When the present application raises the presser foot 20 to the target starting sewing height, as Figure 7 and Figure 8 shown, the presser foot 20 still presses against the starting sewing position 61 of the sewing material to be sewn, then the presser foot 20 exerts pressure on the starting sewing position 61 of the sewing material to be sewn.

[0069] When subsequently sewing the first stitch at the start of sewing, the feed dog 70 moves forward slightly and then sinks downward into the needle plate 50. Before the feed dog 70 sinks downward into the needle plate 50, as Figure 7 shown, since the feed dog 70 has a certain fixing effect on the starting sewing position 61 of the sewing material to be sewn, the sewing material to be sewn will not be pushed backward by the presser foot 20. After the feed dog 70 sinks downward into the needle plate 50, as Figure 8 shown, only the presser foot 20 exerts pressure on the starting sewing position 61 of the sewing material to be sewn; at this time, the force condition of the presser foot 20 is: as Figure 9 shown, the presser foot pressure F1 exerted by the presser foot spring, the horizontal force F2 exerted by the sewing machine housing, and the supporting force F3 exerted by the starting sewing position 61 of the sewing material to be sewn. The presser foot pressure F1 is the driving force for the presser foot 20 to hold down the sewing material; the force condition of the starting sewing position 61 of the sewing material to be sewn is: as Figure 10As shown in the figure, there are gravity G, the pressure F4 applied by the presser foot 20, the vertically upward supporting force F5 applied by the needle plate 50, and the frictional force F6 between the presser foot 20 and the needle plate 50. The maximum value of the frictional force F6 is the maximum static frictional force between the starting sewing part 61 and the needle plate 50. Among them, the supporting force F3 received by the presser foot 20 and the pressure F4 received by the starting sewing part 61 are a pair of action and reaction forces, and their magnitudes are determined by the presser foot pressure F1 applied by the presser foot spring. The specific relationship is: F4 = F3 = F1 / sinβ; the horizontal component force F41 of F4 is: F41 = F4 * cosβ = F1 / tanβ, where β is the angle between the pressure applied by the presser foot 20 to the starting sewing part 61 of the sewing material to be sewn and the horizontal plane, and β = 90° - θ.

[0070] Specifically, in this application, the electric control unit controls the lifting presser foot drive source 30 to act, lifts the presser foot 20 to the required starting sewing target height. At this starting sewing target height, the upward tilt angle θ of the presser foot 20 should satisfy: the horizontal component force F41 of the pressure F4 applied by the presser foot 20 to the starting sewing part 61 of the sewing material to be sewn is not greater than the maximum static frictional force F6 between the starting sewing part 61 of the sewing material to be sewn and the sewing machine needle plate 50. In this way, after the feed dog 70 sinks downward into the needle plate 50 when sewing the first stitch at the start, the presser foot 20 will not push the starting sewing part 61 of the sewing material to be sewn backward away from the sewing needle, achieving the purpose that the starting sewing part 61 of the sewing material to be sewn will not be pushed away by the presser foot 20, effectively avoiding pushing the material at the start of sewing and ensuring normal sewing.

[0071] Step S6: Start sewing; the electric control unit judges whether the set number of stitches for starting sewing is reached; when it is judged that the set number of stitches N for starting sewing is not reached, the electric control unit controls the lifting presser foot drive source 30 not to act and maintains the current starting sewing target height at which the presser foot 20 is lifted; when it is judged that the set number of stitches N for starting sewing is reached, it means that the sewing material to be sewn has completely entered under the presser foot 20. At this time, there is no need to specifically lift the presser foot 20, so the electric control unit controls the lifting presser foot drive source 30 to reset, and the presser foot 20 returns to the normal lowered state, meeting the requirements for the presser foot pressure during normal sewing. Preferably, the set number of stitches for starting sewing is determined according to actual needs and is 1 - 3 stitches.

[0072] Step S7: The sewing machine continues to sew.

[0073] In this way, under the control logic of the starting sewing control method based on lifting the presser foot for feeding involved in this application, the thick material goes through four states from starting sewing to normal sewing. The four states are in sequence: as Figure 11As shown in the figure, first, in the initial state before starting sewing, the presser foot 20 is lowered, and the feed dog 70 protrudes from the needle plate 50. At this time, sewing has not started yet; secondly, starting sewing, the presser foot lifting drive source 30 operates, and the presser foot 20 is slightly lifted to the target height for starting sewing; then, after sewing N stitches, the presser foot lifting drive source 30 resets, the presser foot 20 is lowered, and the presser foot 20 presses on the thick stem; finally, after the sewing of the rear stem of starting sewing is completed, the presser foot 20 presses on the sewing material with normal thickness.

[0074] Therefore, for the starting sewing control method based on presser foot lifting for feeding involved in the present application, when starting sewing on thick materials, a signal for slightly lifting the presser foot 20 is given. Before the feed dog 70 starts to move, or at least before the feed dog 70 sinks downward into the needle plate 50, by controlling the output of the presser foot lifting drive source 30, the lifting height of the presser foot 20 is controlled, and the presser foot 20 is lifted to the target height for starting sewing. Thereby, the upward warping angle θ when the presser foot 20 presses on the starting sewing part 61 of the thick material is reduced, and further, the magnitude of the horizontal component force F41 of the pressure F4 exerted by the presser foot 20 on the starting sewing part 61 of the thick material is reduced, so that the horizontal component force F41 is less than or equal to the maximum static friction force between the starting sewing part 61 of the thick material and the sewing machine needle plate 50, so that the starting sewing part 61 of the sewing material to be sewn will not be pushed backward by the presser foot 20, and reliably keeps the starting sewing part 61 of the sewing material to be sewn at the position close to the rear side of the sewing needle as required by the thick material starting sewing process, enabling the sewing material to feed and sew normally when starting sewing on thick materials, improving the reliability of starting sewing on thick materials, and further enhancing the competitiveness of sewing machine products.

[0075] Furthermore, as Figure 4As shown, the presser foot lifting transmission unit 40 includes a driving cam 41, a first swing rod 42 having a fixed rotation fulcrum, a driving ball 43 rotatably mounted at one end of the first swing rod 42, a first connecting rod 44, a second swing rod 45 having a fixed rotation fulcrum, a second connecting rod 46, a third swing rod 47 having a fixed rotation fulcrum, a presser foot lifting plate 48, and a presser foot pressing block 49 fixed to the upper end of the presser foot rod 10. The driving cam 41 is connected to the presser foot driving source 30 and driven to rotate by the presser foot driving source 30. The driving ball 43 is in contact and cooperation with the outer peripheral surface of the driving cam 41. Two ends of the first connecting rod 44 are respectively hinged to the other end of the first swing rod 42 and one end of the second swing rod 45. Two ends of the second connecting rod 46 are respectively hinged to the other end of the second swing rod 45 and one end of the third swing rod 47. The other end of the third swing rod 47 is hinged to the upper end of the presser foot lifting plate 48. A lifting hook portion is provided on the presser foot lifting plate 48, and a connecting protrusion is provided on the presser foot pressing block 49. The connecting protrusion is engaged with the lifting hook portion. When the presser foot driving source 30 drives the driving cam 41 to rotate, the first swing rod 42 is pushed to rotate through the driving ball 43, and then the second swing rod 45 is driven to rotate through the first connecting rod 44, and then the third swing rod 47 is driven to rotate through the second connecting rod 46, so that the presser foot lifting plate 48 moves upward. The presser foot pressing block 49 is driven to move upward through the engagement between the connecting protrusion and the lifting hook portion, and finally the presser foot rod 10 and the presser foot 20 are driven to move upward. Different output values of the presser foot driving source 30 correspond to different lifting heights of the presser foot 20.

[0076] Preferably, the presser foot lifting transmission unit 40 further includes a mounting plate fixed inside the sewing machine housing. The first swing rod 42 is hinged to the mounting plate by a screw extending left and right, and this screw constitutes the fixed rotation fulcrum of the first swing rod 42. The second swing rod 45 and the third swing rod 47 are both hinged to the sewing machine housing by screws extending front and back. In this embodiment, the presser foot driving source 30 is a motor, preferably a stepping motor. The driving cam 41 is directly fixed to the motor shaft of the presser foot driving source 30 by a screw. By controlling the rotation angle of the motor of the presser foot driving source 30, the lifting height of the presser foot 20 is controlled, that is, the motor rotation angle of the presser foot driving source 30 and the lifting height of the presser foot 20 are in one-to-one correspondence. In other embodiments, the presser foot driving source 30 can also be a linear motor and a worm and worm gear transmission structure.

[0077] Further, F41 = F4 * cosβ = F1 / tanβ = F1 / tan(90° - θ), the maximum static friction force F6 = F5 * μ = (F1 + G) * μ, where G is the gravity of the starting sewing part 61 of the sewing material to be sewn, and μ is the friction coefficient between the starting sewing part 61 of the sewing material to be sewn and the sewing machine needle plate 50. Thus, the maximum value of the upward tilt angle θ of the presser foot 20 is determined. In this application, the maximum value of the upward tilt angle θ of the presser foot 20 is 30°. In addition, in order to meet the requirement of normal feeding, the presser foot 20 needs to provide a downward pressure, and it is required that the lifting height of the presser foot 20 cannot be higher than the thickness of the starting sewing part 61, so the upward tilt angle θ cannot be less than 0°. Therefore, in the above step S5, when the presser foot 20 is lifted to the starting sewing target height, the upward tilt angle θ of the presser foot 20 relative to the horizontal plane is 0° to 30°.

[0078] Further, for different thicknesses of the starting sewing part 61 of the sewing material to be sewn, there are corresponding different starting sewing target heights for the lifting of the presser foot 20, and thus corresponding different outputs of the lift-presser foot drive source 30. The starting sewing target height matching the thickness of the starting sewing part 61 of the sewing material to be sewn can be determined by a three-dimensional model or obtained through experiments. Therefore, as Figure 3 shown, in step S5, the electronic control unit also obtains the thickness of the starting sewing part 61 of the sewing material to be sewn, and the electronic control unit controls the action amplitude of the lift-presser foot drive source 30 according to the thickness of the starting sewing part 61 of the sewing material to be sewn, so that the starting sewing target height is adapted to the thickness of the starting sewing part 61 of the sewing material to be sewn. Preferably, a sewing material thickness detection sensor is also configured in the sewing machine. The sewing material thickness detection sensor is used to detect the thickness of the sewing material under the presser foot 20, and the sewing material thickness detection sensor is communicatively connected to the electronic control unit; in step S5, the electronic control unit obtains the thickness of the starting sewing part 61 of the sewing material to be sewn according to the feedback of the sewing material thickness detection sensor. The sewing material thickness detection sensor can be a laser sensor, a Hall sensor, a displacement sensor, or a camera, etc. Among them, the Hall sensor or the displacement sensor is installed on the presser foot lever 10 and moves synchronously with the presser foot lever 10. Of course, in other embodiments, the thickness of the starting sewing part 61 can also be manually input.

[0079] Further, a starting sewing control mapping table as shown in Table 1 below is pre-stored in the electronic control unit. The starting sewing control mapping table includes multiple groups of mapping relationships, and each group of mapping relationships includes the thickness T n of the starting sewing part 61 of the sewing material to be sewn, the starting sewing target height H n , and the output value A n of the lift-presser foot drive source 30 that correspond one by one. Thus, in step S5, after the electronic control unit obtains the thickness T n of the starting sewing part 61 of the sewing material to be sewn, it determines the corresponding starting sewing target height H n according to the mapping relationship where the thickness T n, so that the thrust provided by the presser foot 20 cannot push away the sewing material to be sewn, but will not hinder the feeding; according to the starting sewing target height H n The corresponding motor rotation angle A of the presser foot lifting drive source 30 is determined according to the mapping relationship where it is located n , the electronic control unit controls the presser foot lifting drive source 30 to output this rotation angle value, and lifts the presser foot 20 to the corresponding starting sewing target height H n .

[0080] Table 1 Starting Sewing Control Mapping Table

[0081] The thickness of the starting sewing part 61 of the sewing material to be sewn The target height of starting sewing The motor rotation angle of the presser foot lifting drive source 30 <![CDATA[T1]]> <![CDATA[H1]]> <![CDATA[A1]]> … … … <![CDATA[T n > <![CDATA[H n > <![CDATA[A n >

[0082] In summary, the starting sewing control method based on presser foot lifting for feeding in this application, when starting to sew thick materials, slightly lifts the presser foot 20 to the starting sewing target height, and the starting sewing target height adapts to the thickness of the starting sewing part 61 of the sewing material to be sewn, preventing the bad phenomenon that the thick material is pushed away by the presser foot 20 during starting sewing. After the starting sewing is completed, the presser foot 20 is automatically lowered to meet the requirements of normal sewing. This starting sewing control method broadens the adaptability of the sewing machine to sewing thick materials and well adapts to the sewing process of starting to sew thick materials.

[0083] After the sewing machine enters the normal sewing process, there will be a situation of sewing over a ridge during the sewing process. Specifically: as Figure 13 shown, when the presser foot 20 passes over the ridge position 62 of the sewing material to be sewn, due to reasons such as the ridge position 62 being too thick or the sewing material being hairy, which reduces the friction coefficient, the feed dog 70 cannot provide sufficient feeding force, resulting in the situation of spinning in place and not being able to pass through smoothly or having a rough passing over the ridge during passing over the ridge, and then resulting in a denser stitch pitch. At this time, some operators will slightly lift the presser foot with their knees to assist in feeding during passing over the ridge, but using the manual method will inevitably require reducing the speed, which not only increases the operation difficulty but also easily reduces the work effect. Based on the characteristic of the automatic presser foot lifting of the sewing machine in this application, this application can provide a control method for passing over the ridge to ensure a smooth passing over the ridge.

[0084] As Figure 12 shown, the control method for passing over the ridge based on presser foot lifting for feeding provided in this application successively includes the following steps.

[0085] Step P1, the electronic control unit receives the signal for passing over the ridge; for example: the electronic control unit judges that there is a ridge position 62 according to the feedback of the sewing material thickness detection sensor and needs to pass over the ridge.

[0086] Step P2, the electronic control unit controls the presser foot lifting drive source 30 to act, and the presser foot lifting drive source 30 drives the presser foot 20 to move upward through the presser foot transmission unit 40, and lifts the presser foot 20 to the passing over the ridge target height. At this time, the force condition of the presser foot 20 is: as Figure 15As shown, the vertical downward pressure F1 of the presser foot spring, the horizontal force F2 applied by the sewing machine housing, and the supporting force F3 applied by the stem 62 of the sewing material to be sewn; the force condition of the stem 62 of the sewing material to be sewn is: Figure 15 As shown, gravity G, pressure F4 applied by presser foot 20, vertical support force F5 applied by needle plate 50, and cloth feeding force F7. The support force F3 applied by presser foot 20 and the pressure F4 applied by stem 62 form a pair of action and reaction forces. In particular, the target height of stem passing should satisfy: reducing the upward angle θ when presser foot 20 presses against stem 62 of sewing material to be sewn, thereby reducing the magnitude of horizontal component force F41 of pressure F4 applied by presser foot 20 to stem 62 of sewing material to be sewn, so that the horizontal component force F41 is less than or equal to cloth feeding force F7, improving the smoothness of feeding, and making stem 62 smoothly fed between presser foot 20 and needle plate 50, so as to achieve smooth stem passing.

[0087] Step P3, the sewing machine continues to sew until the presser foot 20 climbs up to the stem position 62 of the sewing material to be sewn, and the presser foot 20 is directly above the stem position 62. Figure 14 As shown, it is judged that the upper stem is finished.

[0088] Step P4, the electronic control unit controls the presser foot lifting driving source 30 to reset, and the presser foot 20 returns to the normal lowered state, meeting the requirements of normal sewing for the presser foot pressure.

[0089] Step P5: The sewing machine continues to sew.

[0090] Thus, under the control logic of the method for controlling the material passing through the sewing stem based on the presser foot lifting feeding involved in the present application, the material passes through the sewing stem to the normal sewing process through four states, and the four states are: Figure 16 As shown, first, when the sewing process starts, the presser foot 20 is put down; secondly, when the presser foot 20 is on the sewing machine, the presser foot lifting driving source 30 is activated, and the presser foot 20 is slightly lifted to the target height of the sewing process; then, the presser foot 20 is pressed on the sewing position 62, the sewing process ends, the presser foot lifting driving source 30 is reset, and the presser foot 20 is put down; finally, when the sewing process ends, the presser foot 20 is pressed on the sewing material of normal thickness.

[0091] Furthermore, when the presser foot 20 is lifted to the target height over the stem, the upward angle θ of the presser foot 20 relative to the horizontal plane is 0°~30°, which can not only enable the presser foot 20 to provide downward pressure to meet normal feeding, but also reduce the obstruction of the presser foot 20 to the stem position 62, so that the stem position 62 can be smoothly fed between the presser foot 20 and the needle plate 50.

[0092] Furthermore, for different thicknesses of the sewing material 62, there are corresponding different target heights of the presser foot 20 to be lifted, and thus corresponding different outputs of the presser foot lifting driving source 30. The target height of the sewing material 62 to be sewn that matches the thickness of the sewing material 62 can be determined by a three-dimensional model or obtained by experiments. Figure 12As shown, in step P2, the electronic control unit obtains the thickness of the rib position 62 of the sewing material to be sewn according to the feedback of the sewing material thickness detection sensor, and the electronic control unit controls the action amplitude of the presser foot lifting drive source 30 according to the thickness of the rib position 62 of the sewing material to be sewn, so that the target height for passing over the rib is adapted to the thickness of the rib position 62 of the sewing material to be sewn.

[0093] Further, a rib-passing control mapping table as shown in Table 2 below is pre-stored in the electronic control unit. The rib-passing control mapping table includes multiple groups of mapping relationships, and each group of mapping relationships includes the thickness T of the rib position 62 of the sewing material to be sewn in one-to-one correspondence n , the target height H for passing over the rib n , and the output value A of the presser foot lifting drive source 30 n . Thus, in step P2, after the electronic control unit obtains the thickness T of the rib position 62 of the sewing material to be sewn n , according to the thickness T of the rib position 62 of the sewing material to be sewn n , it determines the corresponding target height H for passing over the rib according to the mapping relationship where it is located n , and determines the corresponding motor rotation angle A of the presser foot lifting drive source 30 according to the mapping relationship where the target height H for passing over the rib is located n . The electronic control unit controls the presser foot lifting drive source 30 to output this rotation angle value, and lifts the presser foot 20 to the corresponding target height H for passing over the rib n to smoothly pass over the rib. n

[0094] Table 2 Rib-passing control mapping table

[0095] The thickness of the rib position 62 of the sewing material to be sewn The target height of passing over the rib The motor rotation angle of the presser foot lifting drive source 30 <![CDATA[T1]]> <![CDATA[H1]]> <![CDATA[A1 <!-- 8 -->]]> … … … <![CDATA[T n > <![CDATA[H n > <![CDATA[A n >

[0096] In summary, the rib-passing control method based on presser foot lifting for feeding in the present application lifts the presser foot 20 to the target height for passing over the rib during rib-passing sewing, reduces the upward tilt angle θ of the presser foot 20, thereby reducing the resistance of the presser foot 20 to the rib position 62, ensuring normal feeding and sewing during rib-passing, and thus enhancing the competitiveness of the sewing machine product. After passing over the rib, the presser foot 20 is automatically lowered again to meet the requirements of normal sewing.

[0097] In addition, the starting sewing control mapping table and the rib-passing control mapping table can be combined into one control mapping table.

[0098] In summary, the present invention effectively overcomes various disadvantages in the prior art and has high industrial utilization value.

[0099] The above embodiments are only illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A seam control method based on presser foot lifting and feeding, characterized in that: The seam start control method comprises the following steps: S1, configuring an electronic control unit in a sewing machine, a presser foot rod movably supported in a housing of the sewing machine, a presser foot installed at the lower end of the presser foot rod, and a presser foot lifting mechanism, wherein the presser foot lifting mechanism comprises a presser foot lifting driving source and a presser foot lifting transmission unit, wherein the presser foot lifting driving source is connected to the presser foot rod through the presser foot lifting transmission unit, and the presser foot lifting driving source is communicatively connected to the electronic control unit; S2, placing the sewing material to be sewn, at this time, the presser foot is raised, the needle in the sewing machine is located at the upper stop position, and the feed dog in the sewing machine emerges from the needle plate; S3, placing the sewing material to be sewn in place, with the sewing starting point of the sewing material being immediately below the sewing machine needle, and the two being arranged one after the other along the feeding direction of the sewing machine; S4, lowering the presser foot, and the electronic control unit receives a signal for starting to sew thick materials; S5, before the feed dog sinks downward into the needle plate when sewing the first stitch, the electronic control unit controls the presser foot lifting driving source to operate, and the presser foot lifting driving source drives the presser foot rod and the presser foot to move upward through the presser foot lifting transmission unit, so as to lift the presser foot to the target seam starting height and reduce the upward angle of the presser foot relative to the horizontal plane; at this time, the presser foot is still pressed against the seam starting position of the sewing material to be sewn, and the horizontal component of the pressure applied by the presser foot to the seam starting position of the sewing material to be sewn is not greater than the maximum static friction between the seam starting position of the sewing material to be sewn and the sewing machine needle plate; S6, after the set number of stitches is reached, the electronic control unit controls the presser foot lifting driving source to reset, the presser foot rod and the presser foot move down, and the presser foot returns to a lowered state; S7: the sewing machine continues sewing.

2. The seam start control method based on presser foot lifting and feeding according to claim 1, characterized in that: In step S5, the electronic control unit also obtains the thickness of the seam starting part of the sewing material to be sewn, and controls the movement amplitude of the presser foot lifting drive source according to the thickness of the seam starting part of the sewing material to be sewn, so that the seam starting target height is adapted to the thickness of the seam starting part of the sewing material to be sewn.

3. The seam start control method based on presser foot lifting and feeding according to claim 2, characterized in that: In the step S1, the sewing machine is further provided with a sewing material thickness detection sensor, the sewing material thickness detection sensor is used to detect the thickness of the sewing material under the presser foot, and the sewing material thickness detection sensor is communicatively connected with the electronic control unit; In the step S5, the electronic control unit obtains the thickness of the seam starting point of the sewing material to be sewn according to the feedback of the sewing material thickness detection sensor.

4. The seam start control method based on presser foot lifting and feeding according to claim 2, characterized in that: The electronic control unit has a pre-stored seam start control mapping table, which includes a plurality of mapping relationships, each of which includes a one-to-one correspondence of the thickness of the seam start position of the sewing material to be sewn, the seam start target height, and the output value of the presser foot lifting drive source; In the step S5, after the electronic control unit obtains the thickness of the seam starting part of the sewing material to be sewn, the action amplitude of the presser foot lifting driving source is controlled according to the mapping relationship of the thickness of the seam starting part of the sewing material to be sewn.

5. The seam start control method based on presser foot lifting and feeding according to claim 1, characterized in that: In step S5, when the presser foot is lifted to the target seam start height, the upward angle of the presser foot relative to the horizontal plane is 0° to 30°.

6. The seam start control method based on presser foot lifting and feeding according to claim 1, characterized in that: The presser foot lifting transmission unit includes a driving cam, a first rocker rod with a fixed rotating fulcrum, a driving ball rotatably mounted at one end of the first rocker rod, a first connecting rod, a second rocker rod with a fixed rotating fulcrum, a second connecting rod, a third rocker rod with a fixed rotating fulcrum, a presser foot lifting plate, and a presser foot lifting block fixed at the upper end of the presser foot rod. The driving cam is connected to a presser foot lifting driving source, and the driving ball is in contact with the outer circumferential surface of the driving cam. The two ends of the first connecting rod are respectively hinged to the other end of the first rocker rod and one end of the second rocker rod, the two ends of the second connecting rod are respectively hinged to the other end of the second rocker rod and one end of the third rocker rod, and the other end of the third rocker rod is hinged to the upper end of the presser foot lifting plate, a lifting hook is provided on the presser foot lifting plate, and a connecting protrusion is provided on the presser foot lifting block, and the connecting protrusion is engaged with the lifting hook.

7. The seam start control method based on presser foot lifting feeding according to claim 1, 2 or 6, characterized in that: The presser foot lifting driving source is a motor.

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