Sewing starting control method based on adjustment of pressure of presser foot

Abstract

The invention provides a sewing starting control method based on presser foot pressure adjustment, which comprises the following steps: an electric control unit and a presser foot pressure adjustment mechanism are arranged in a sewing machine, and the presser foot pressure adjustment mechanism comprises a pressure adjustment driving source, a pressure adjustment transmission unit, a pressure adjustment rod and a pressure adjustment spring; a sewing material to be sewn is placed, and the sewing starting part of the sewing material to be sewn is close to the position under a sewing machine needle; the electric control unit controls the pressure adjusting driving source to act after receiving the thick material seam starting signal, and the pressure applied to the presser foot rod and the presser foot by the pressure adjusting spring is adjusted to the seam starting target presser foot pressure; the horizontal component force of the pressure applied by the presser foot to the sewing starting part of the sewing material to be sewn is not larger than the maximum static friction force between the sewing starting part of the sewing material to be sewn and the sewing machine needle plate, the purpose that the sewing starting part of the sewing material to be sewn cannot be pushed away by the presser foot is achieved, sewing starting material pushing is effectively avoided, and normal sewing is guaranteed. After the set number of stitches is full, the electric control unit controls the pressure adjusting driving source to reset and the pressure adjusting rod to reset; the sewing machine continues sewing.

Description

Technical Field

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

[0002] When a flat sewing machine sews thick materials such as down jackets and cotton-padded clothes, the starting sewing process requires the starting point of the thick material to be placed in front of the sewing needle, that is, the starting sewing part of the thick material needs to be closely adjacent to the directly below of 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 raised state; then, the presser foot is lowered, and the sewing needle moves downward to pierce the material, as Figure 2 shown, and the starting sewing begins. However, during this starting sewing process, there is an easy occurrence of a starting 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 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 into the space between the presser foot and the needle plate. However, it is impossible to control the force well when manually pushing the material, which not only increases the operation difficulty but also easily causes broken needles during starting sewing. 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 sewing control method based on adjusting the pressure of a presser foot to avoid the starting material pushing phenomenon.

[0004] To achieve the above purpose, the present invention provides a starting sewing control method based on adjusting the pressure of a presser foot. The starting sewing control method includes the following steps:

[0005] S1. Configure an electronic control unit, a presser foot bar 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 bar, and a presser foot pressure adjustment mechanism in the sewing machine. The presser foot pressure adjustment mechanism includes a pressure adjustment driving source, a pressure adjustment transmission unit, a pressure adjustment rod that is supported in the sewing machine housing so as to be movable up and down, and a pressure adjustment spring. The pressure adjustment driving source is in transmission connection with the pressure adjustment rod through the pressure adjustment transmission unit. The upper and lower ends of the pressure adjustment spring are respectively connected to the pressure adjustment rod and the presser foot bar. The pressure adjustment driving source is in communication connection with the electronic control unit;

[0006] S2. Place the sewing material to be sewn. At this time, the presser foot is raised, 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 sewing part of the sewing material to be sewn is closely adjacent to the directly below of the sewing needle in 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 starting sewing signal of the thick material;

[0009] S5. Before the feed dog sinks downward into the needle plate when starting to sew the first stitch, the electronic control unit controls the pressure regulating drive source to act. The pressure regulating drive source drives the pressure regulating rod to move through the pressure regulating transmission unit, and adjusts the pressure exerted by the pressure regulating spring on the presser foot rod and the presser foot to the starting sewing target presser foot pressure.

[0010] Under the action of the starting sewing target presser foot pressure, the presser foot 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 force between the starting sewing part of the material to be sewn and the sewing machine needle plate.

[0011] S6. After sewing the set number of stitches at the start, the electronic control unit controls the pressure regulating drive source to reset, and the pressure regulating rod resets.

[0012] S7. The sewing machine continues to sew.

[0013] 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 pressure regulating drive source according to the thickness of the starting sewing part of the material to be sewn, so that the magnitude of the starting sewing target presser foot pressure is adapted to the thickness of the starting sewing part of the material to be sewn.

[0014] 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.

[0015] 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.

[0016] 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 presser foot pressure, and the output value of the pressure regulating drive source that correspond to each other.

[0017] 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 pressure regulating drive source according to the mapping relationship where the thickness of the starting sewing part of the material to be sewn is located.

[0018] Further, the starting sewing target presser foot pressure is: (F + G * μ / (1 / tanβ - μ)) / 2;

[0019] In the formula, F is the minimum presser foot pressure value and is a set value, G is the gravity of the starting sewing part of the sewing material to be sewn, μ is the friction coefficient between the starting sewing part of the sewing material to be sewn and the sewing machine needle plate, and β is the angle between the pressure applied by the presser foot to the starting sewing part of the sewing material to be sewn and the horizontal plane.

[0020] Further, the pressure adjustment transmission unit includes an adjustment crank, a first connecting rod, a first swing rod with a fixed rotation fulcrum, a second connecting rod, a second swing rod with a fixed rotation fulcrum, a third connecting rod, a third swing rod with a fixed rotation fulcrum, a transmission slider, and a slider seat. The adjustment crank is connected to the pressure adjustment driving source and is driven by the pressure adjustment driving source to rotate. The two ends of the first connecting rod are respectively hinged to the adjustment crank and the first swing rod. The two ends of the second connecting rod are respectively hinged to the first swing rod and the second swing rod. The two ends of the third connecting rod are respectively hinged to the second swing rod and the third swing rod. The transmission slider is hinged to the third swing rod. A horizontal chute that slidably cooperates with the transmission slider is provided in the slider seat. The transmission slider abuts against the upper and lower chute walls of the horizontal chute. The slider seat is fixed on the pressure adjustment rod.

[0021] Further, the pressure adjustment driving source is a motor.

[0022] Further, a spring guide rod is inserted into the pressure adjustment rod. The pressure adjustment spring is sleeved on the spring guide rod and its upper end abuts against the pressure adjustment rod. A pressure block is fixed on the presser foot rod. The lower end of the pressure adjustment spring is sleeved on the top of the presser foot rod and abuts against the pressure block.

[0023] As described above, the starting sewing control method based on adjusting the presser foot pressure involved in the present invention has the following beneficial effects:

[0024] Based on the setting of the presser foot pressure adjustment mechanism in the sewing machine, the present application can adjust the presser foot pressure. Thus, when starting sewing, the present application adjusts the pressure applied by the pressure adjustment spring to the presser foot rod and the presser foot by controlling the action of the pressure adjustment driving source, that is, adjusts the pressure applied by the presser foot to the starting sewing part of the sewing material to be sewn after the presser foot is lowered, so that the horizontal component of this pressure is less than or equal to the maximum static friction force between the starting sewing part of the sewing material to be sewn and the sewing machine needle plate, achieving the purpose that the starting sewing part of the sewing material to be sewn will not be pushed away by the presser foot, effectively avoiding starting sewing material pushing and ensuring normal sewing. Description of the Drawings

[0025] Figure 1 It is a schematic diagram of the placement of the starting sewing part of thick material on the sewing machine needle plate when starting sewing thick material.

[0026] Figure 2 It is a schematic diagram of the state of the presser foot pushing the material when starting sewing in the prior art.

[0027] Figure 3This is the control block diagram of the starting seam control method based on adjusting the presser foot pressure in this application.

[0028] Figure 4 This is the connection schematic diagram of the presser foot lever, presser foot and presser foot pressure adjusting mechanism in this application.

[0029] Figure 5 This is the connection block diagram of the sewing material thickness detection sensor and the pressure adjusting drive source with the electronic control unit in this application.

[0030] Figure 6 This is the force analysis diagram of the starting seam part of the sewing material to be sewn after the feed dog sinks into the needle plate during the starting seam of thick materials in this application.

[0031] Figure 7 This is the schematic diagram of the movement track of the feed dog in this application.

[0032] Figure 8 This is the state schematic diagram of the starting seam part of the sewing material to be sewn during the downward movement of the sewing needle at the time of the first starting seam in this application.

[0033] Figure 9 This is the control block diagram of the over-bar control method based on adjusting the presser foot pressure in this application.

[0034] Figure 10 This is the state schematic diagram during the over-bar in the middle of sewing.

[0035] Figure 11 For Figure 10 This is the state schematic diagram of the presser foot on the bar position.

[0036] Figure 12 This is the force analysis diagram of the bar position of the sewing material to be sewn during the over-bar in the middle of sewing in this application.

[0037] Description of component labels

[0038] 11 Starting seam part

[0039] 12 Bar position

[0040] 20 Presser foot lever

[0041] 30 Presser foot

[0042] 40 Pressure adjusting drive source

[0043] 50 Pressure adjusting rod

[0044] 60 Pressure adjusting spring

[0045] 70 Pressure adjusting transmission unit

[0046] 71 Adjusting crank

[0047] 72 First connecting rod

[0048] 73 First swing rod

[0049] 74 Second connecting rod

[0050] 75 Second swing rod

[0051] 76 Third connecting rod

[0052] 77 Third swing rod

[0053] 78 Transmission slider

[0054] 79 Slider seat

[0055] 710 Mounting plate

[0056] 80 Pressing block

[0057] 90 Needle plate

[0058] 110 Feed tooth Specific implementation manner

[0059] 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.

[0060] 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 limiting 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 narration 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 in which the present invention can be implemented.

[0061] It should also be noted that when an element is referred to as "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 "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.

[0062] In addition, the descriptions involving "first", "second", etc. in this application are for descriptive purposes only, 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. In addition, 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.

[0063] This application provides a sewing machine with adjustable presser foot pressure, and the type of this sewing machine is a flat sewing machine. Based on the characteristic of adjustable presser foot pressure of the sewing machine, this application also provides a starting seam control method based on adjusting the presser foot pressure, and a seam crossing control method based on adjusting the presser foot pressure, that is, the sewing machine with adjustable presser foot pressure can be used for starting seam control and seam crossing control at the same time.

[0064] As Figure 4 shown, the sewing machine with adjustable presser foot pressure 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 lever 20 that is supported in the sewing machine housing so as to be movable up and down through a bushing, a presser foot 30 installed at the lower end of the presser foot lever 20, and a presser foot pressure adjusting mechanism. The presser foot pressure adjusting mechanism includes a pressure adjusting drive source 40, a pressure adjusting transmission unit 70, a pressure regulating lever 50 that is supported in the sewing machine housing so as to be movable up and down through a bushing, and a pressure regulating spring 60 that extends vertically. The pressure adjusting drive source 40 is in transmission connection with the pressure regulating lever 50 through the pressure adjusting transmission unit 70 to drive the pressure regulating lever 50 to move up or down. The pressure regulating lever 50 and the presser foot lever 20 are vertically distributed and coaxial. The upper and lower ends of the pressure regulating spring 60 are respectively connected to the pressure regulating lever 50 and the presser foot lever 20. Thus, when the pressure adjusting drive source 40 drives the pressure regulating lever 50 to move down through the pressure adjusting transmission unit 70, the compression amount of the pressure regulating spring 60 increases, and the pressure (i.e., the presser foot pressure) exerted by the pressure regulating spring 60 on the presser foot lever 20 and the presser foot 30 increases, so the pressure exerted by the presser foot 30 on the sewing material after the presser foot 30 presses against the sewing material also increases accordingly; conversely, when the pressure adjusting drive source 40 drives the pressure regulating lever 50 to move up through the pressure adjusting transmission unit 70, the compression amount of the pressure regulating spring 60 decreases, and the pressure (i.e., the presser foot pressure) exerted by the pressure regulating spring 60 on the presser foot lever 20 and the presser foot 30 decreases, so the pressure exerted by the presser foot 30 on the sewing material after the presser foot 30 presses against the sewing material also decreases accordingly. Therefore, by adjusting the output of the pressure adjusting drive source 40, the pressure exerted by the pressure regulating spring 60 on the presser foot lever 20 and the presser foot 30 can be adjusted, that is, the presser foot pressure can be adjusted. In addition, as Figure 5 shown, in the sewing machine, the pressure adjusting drive source 40 is in communication connection with the electronic control unit, and the output of the pressure adjusting drive source 40 is controlled by the electronic control unit.

[0065] AsFigure 3 As shown in the figure, the starting sewing control method based on adjusting the presser foot pressure involved in the present application successively includes the following steps:

[0066] Step S1: Configure the sewing machine with adjustable presser foot pressure. Then, the sewing machine is at least equipped with an electronic control unit, a presser foot lever 20, a presser foot 30, and a presser foot pressure adjusting mechanism. In addition, as Figure 8 shown, the sewing machine also has a needle plate 90 fixed to the sewing machine table board, a tooth carrier, a feed dog 110 fixed on the tooth carrier, a feed lifting 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 90. The feed lifting mechanism is connected to the tooth carrier and drives the tooth carrier and the feed dog 110 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 110 is an ellipse, as Figure 7 shown; when the feed dog 110 emerges upward from the tooth groove of the needle plate 90, the feed dog 110 contacts the sewing material. Under the action of the feed dog 110, 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 towards 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.

[0067] Step 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 emerges from the needle plate.

[0068] Step S3: After the sewing material to be sewn is placed in place, the presser foot 30 is still in the lifted state. The sewing material to be sewn is thick material. According to the starting sewing process requirements of the thick material, the starting sewing part 11 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 directions, as Figure 1 shown. Then, the starting sewing part 11 of the sewing material to be sewn and the sewing needle of the sewing machine are distributed successively in the front and back directions along the feeding direction of the sewing machine. In addition, the starting sewing part 11 of the thick material has been folded multiple times to form a thick stem start. That is, the front end face of the starting sewing part 11 facing the sewing needle is a shape similar to a circle.

[0069] Step S4: Sewing starts, and the presser foot 30 is lowered. The electronic control unit receives the thick material starting sewing signal. After the presser foot 30 is lowered, the presser foot 30 presses against the starting sewing part 11 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 110, the feed dog 110 is in the Figure 7At the position of point A on its movement trajectory as shown, the feed dog 110 is in a state of protruding from the tooth groove of the needle plate 90 at this time. Therefore, after placing the sewing material to be sewn and lowering the presser foot 30, as Figure 8 shown, the feed dog 110 has a certain fixing effect on the sewing material to be sewn, reliably restricting the sewing material to be sewn from being pushed backward. The thick material start sewing signal can be manually input.

[0070] Step S5: Before the feed dog sinks downward into the needle plate when sewing the first stitch, the electronic control unit controls the pressure regulating drive source 40 to act. The pressure regulating drive source 40 drives the pressure regulating rod 50 to move through the pressure regulating transmission unit 70, and adjusts the pressure applied by the pressure regulating spring 60 to the presser foot rod 20 and the presser foot 30 to the start sewing target presser foot pressure. Therefore, it can be that before starting to sew the first stitch, the electronic control unit has controlled the pressure regulating drive source 40 to act and has adjusted the pressure to the start sewing target presser foot pressure; it can also be that during the process of the sewing needle moving downward when starting to sew the first stitch and before the feed dog 110 sinks downward into the needle plate 90, the electronic control unit controls the pressure regulating drive source 40 to act and adjusts the pressure to the start sewing target presser foot pressure. Usually, after the sewing machine is powered on and started, its initial presser foot pressure is the normal presser foot pressure corresponding to normal sewing. The start sewing target presser foot pressure required in this application is less than the normal presser foot pressure. In this step S5, the pressure regulating drive source 40 drives the pressure regulating rod 50 to move upward through the pressure regulating transmission unit 70, and reduces the presser foot pressure from the normal presser foot pressure to the start sewing target presser foot pressure.

[0071] After adjusting the presser foot pressure to the start sewing target presser foot pressure, the presser foot 30 still presses against the start sewing part 11 of the sewing material to be sewn. As Figure 6 shown, under the action of the start sewing target presser foot pressure applied by the pressure regulating spring 60 to the presser foot rod 20 and the presser foot 30, the presser foot 30 applies pressure to the start sewing part 11 of the sewing material to be sewn. Under the action of only the presser foot 30 applying pressure to the start sewing part 11 of the sewing material to be sewn, that is, when sewing the first stitch later, after the feed dog 110 sinks downward into the needle plate 90, the force conditions of the presser foot 30 and the start sewing part 11 of the sewing material to be sewn are as Figure 6As shown in the figure. The force conditions of the presser foot 30 are as follows: the vertically downward presser foot pressure F1 applied by the pressure regulating spring 60, the horizontal force F2 applied by the sewing machine housing, and the supporting force F3 applied by the starting sewing part 11 of the sewing material to be sewn; the force conditions of the starting sewing part 11 of the sewing material to be sewn are as follows: the gravity G, the pressure F4 applied by the presser foot 30, the vertically upward supporting force F5 applied by the needle plate 90, and the frictional force F6 between the needle plate 90. The maximum value of the frictional force F6 is the maximum static frictional force between the starting sewing part 11 and the needle plate 90. The supporting force F3 received by the presser foot 30 and the pressure F4 received by the starting sewing part 11 are a pair of action and reaction forces, and their magnitudes are determined by the presser foot pressure F1 applied by the pressure regulating spring 60. In particular, when starting to sew thick materials in this application, the presser foot pressure F1 applied by the pressure regulating spring 60 is adjusted to the required starting sewing target presser foot pressure, which should satisfy that the horizontal component force F41 of the pressure F4 applied by the presser foot 30 to the starting sewing part 11 of the sewing material to be sewn is not greater than the maximum static frictional force between the starting sewing part 11 of the sewing material to be sewn and the sewing machine needle plate 90. In this way, when starting to sew the first stitch subsequently, after the feed dog 110 moves forward slightly and then sinks into the needle plate 90, only the presser foot 30 applies pressure to the starting sewing part 11 of the sewing material to be sewn. However, at this time, since the horizontal component force F41 of the pressure F4 applied by the presser foot 30 to the starting sewing part 11 of the sewing material to be sewn is not greater than the maximum static frictional force between the starting sewing part 11 of the sewing material to be sewn and the sewing machine needle plate 90, the presser foot 30 will not push the starting sewing part 11 of the sewing material to be sewn backward away from the sewing needle, achieving the purpose that the starting sewing part 11 of the sewing material to be sewn will not be pushed away by the presser foot 30, effectively avoiding pushing the material at the start of sewing and ensuring normal sewing.

[0072] Step S6: Start sewing.

[0073] The electronic control unit determines whether the set number of stitches for starting sewing is reached; when it is determined that the set number of stitches N for starting sewing has not been reached, the electronic control unit controls the pressure regulating drive source 40 not to act and maintains the current starting sewing target presser foot pressure; when it is determined that the set number of stitches N for starting sewing has been reached, the electronic control unit controls the pressure regulating drive source 40 to reset, the pressure regulating rod 50 moves downward and resets, and then the presser foot pressure of the sewing machine returns to the initial presser foot pressure. In this embodiment, it is the normal presser foot pressure corresponding to normal sewing, which meets the requirements for the presser foot pressure in normal sewing. Preferably, the set number of stitches for starting sewing is determined according to actual needs and is 1 - 3 stitches.

[0074] Step S7: The sewing machine continues to sew.

[0075] Therefore, the starting seam control method based on adjusting the presser foot pressure involved in the present application controls the magnitude of the presser foot pressure during the starting seam of thick materials, so that the horizontal component of the pressure exerted by the presser foot 30 on the starting seam portion 11 of the material to be sewn is less than or equal to the maximum static friction force between the starting seam portion 11 of the material to be sewn and the sewing machine needle plate 90, so that the starting seam portion 11 of the material to be sewn will not be pushed backward by the presser foot 30, and reliably keeps the starting seam portion 11 of the material to be sewn at the position close to the rear side of the sewing needle as required by the thick material starting seam process, enabling the material to be fed normally during the thick material starting seam, improving the reliability of the thick material starting seam, and further enhancing the competitiveness of the sewing machine product.

[0076] Further, as Figure 4 shown, the pressure adjustment transmission unit 70 includes an adjustment crank 71, a first connecting rod 72, a mounting plate 710 fixed inside the sewing machine housing, a first swing rod 73 hinged to the mounting plate 710 by a screw extending left and right, a second connecting rod 74, a second swing rod 75 hinged to the sewing machine housing by a screw extending front and back, a third connecting rod 76, a third swing rod 77 hinged to the sewing machine housing by a screw extending front and back, a transmission slider 78, and a slider seat 79. The first swing rod 73, the second swing rod 75, and the third swing rod 77 each have their own fixed rotation fulcrums. The adjustment crank 71 is connected to the pressure adjustment driving source 40 and driven by the pressure adjustment driving source 40 to rotate. The two ends of the first connecting rod 72 are respectively hinged to the adjustment crank 71 and the first swing rod 73. The lower end and the upper end of the second connecting rod 74 are respectively hinged to the first swing rod 73 and the second swing rod 75. The two ends of the third connecting rod 76 are respectively hinged to the right end of the second swing rod 75 and the third swing rod 77. The transmission slider 78 is hinged to the left end of the third swing rod 77. A horizontal chute that slidably cooperates with the transmission slider 78 is provided in the slider seat 79. The horizontal chute is a chute extending left and right. The transmission slider 78 abuts against the upper chute wall and the lower chute wall of the horizontal chute. The slider seat 79 is fixed on the pressure regulating rod 50. When the pressure adjustment driving source 40 drives the adjustment crank 71 to rotate, the first swing rod 73 is driven to swing around its fixed rotation fulcrum through the first connecting rod 72, then the second swing rod 75 is driven to swing around its fixed rotation fulcrum through the second connecting rod 74, and then the third swing rod 77 is driven to swing around its fixed rotation fulcrum through the third connecting rod 76. The transmission slider 78 swings synchronously with the left end of the third swing rod 77. The left and right displacement is offset by the left and right movement of the transmission slider 78 in the horizontal chute. Finally, the transmission slider 78 drives the slider seat 79 and the pressure regulating rod 50 to move up or down together to achieve the adjustment of the presser foot pressure.

[0077] Preferably, as Figure 4As shown, a spring guide rod is inserted into the pressure regulating rod 50. That is, a blind hole with an opening facing downward is formed in the lower part of the pressure regulating rod 50, and the upper part of the spring guide rod is inserted into the blind hole of the pressure regulating rod 50; the pressure regulating spring 60 is sleeved on the spring guide rod, and the upper end of the pressure regulating spring 60 abuts against the pressure regulating rod 50; a pressing block 80 is fixed on the pressing foot rod 20, and the lower end of the pressure regulating spring 60 is sleeved on the top of the pressing foot rod 20 and abuts against the pressing block 80. In this way, the pressure regulating spring 60 is reliably connected between the pressure regulating rod 50 and the pressing foot rod 20.

[0078] Furthermore, as Figure 4 shown, the pressure regulating driving source 40 is a motor. At this time, the adjusting crank 71 is directly fixed on the motor shaft of the pressure regulating driving source 40 by screws. Of course, in other embodiments, the pressure regulating driving source 40 can also be a linear motor and a worm and worm gear structure.

[0079] Furthermore, Figure 6 In the view, the magnitude relationship between the forces is: F4 = F3 = F1 / sinβ; the horizontal component F41 of F4 is: F41 = F4*cosβ = F1 / tanβ; F5 = F4*sinβ + G = F1 + G; the maximum static friction force F6 = F5*μ = (F1 + G)*μ; where: G is the gravity of the starting sewing part 11 of the sewing material to be sewn, μ is the friction coefficient between the starting sewing part 11 of the sewing material to be sewn and the sewing machine needle plate 90, and β is the angle between the pressure applied by the pressing foot 30 to the starting sewing part 11 of the sewing material to be sewn and the horizontal plane. When β and μ remain unchanged, by controlling the pressing foot pressure F1 applied by the pressure regulating spring 60 to control the horizontal component F41 of the pressure F4 applied by the pressing foot 30 to the starting sewing part 11, so that F41 is less than or equal to the maximum static friction force F6, the effect of not pushing the material during starting sewing is achieved. In addition, according to the requirement of F41 ≤ F6, there is a maximum value for the pressing foot pressure F1 applied by the pressure regulating spring 60 during starting sewing control.

[0080] Furthermore, the value range of the starting sewing target pressing foot pressure in this application is as follows.

[0081] First of all, there is a maximum value for the starting sewing target pressing foot pressure: according to F41 ≤ F6, it can be obtained that F1 / tanβ ≤ (F1 + G)*μ, then F1 ≤ G*μ / (1 / tanβ - μ), so the maximum value of the starting sewing target pressing foot pressure is G*μ / (1 / tanβ - μ); μ takes the minimum value of the maximum static friction coefficients of various sewing materials and various needle plates 90 under common working conditions; G is related to the sewing material parameters and takes the gravity when the thickness of the sewing material is the smallest; β is related to the thickness of the starting sewing part 11 of the sewing material to be sewn, and the thicker the thickness, the smaller β.

[0082] Secondly, the starting sewing target presser foot pressure cannot be too small. Once the starting sewing target presser foot pressure is too small, there will be a situation where the feeding teeth 110 are not pressed deep enough into the starting sewing part 11 during the starting sewing process, resulting in insufficient feeding force, so that the sewing material to be sewn does not have enough speed to keep up with the movement of the feeding teeth 110, and slipping occurs between the feeding teeth 110 and the sewing material to be sewn. Therefore, there is a minimum value for the starting sewing target presser foot pressure to avoid slipping between the feeding teeth 110 and the sewing material to be sewn due to insufficient feeding force and ensure the sewing quality. To achieve no slipping between the feeding teeth 110 and the sewing material to be sewn, it is necessary to satisfy: f - F4 * cosβ = f - F1 / tanβ ≥ m.a. In the formula, f is the maximum feeding force of the feeding teeth 110. The feeding force of the feeding teeth 110 first increases rapidly, then slowly increases, and finally remains basically unchanged with the increase of the presser foot pressure; a is the maximum acceleration of the feeding teeth 110 in the horizontal direction at the starting sewing speed; m is the mass of the starting sewing part 11 of the sewing material to be sewn. In this way, the minimum value of F1 is obtained, which is the minimum value of the starting sewing target presser foot pressure, and it is defined as the minimum presser foot pressure value F. In this application, the minimum presser foot pressure value F is obtained by directly solving the analytical solution or directly testing method and stored in the electronic control unit in advance, so the minimum presser foot pressure value F is a set value.

[0083] Therefore, in this application, the value range of the starting sewing target presser foot pressure F1 is: F ≤ F1 ≤ G * μ / (1 / tanβ - μ). Preferably, the starting sewing target presser foot pressure F1 in this application takes the middle value of its range, that is, at the thickness of the starting sewing part 11 of a certain sewing material to be sewn, the starting sewing target presser foot pressure F1 is: F1 = (F + G * μ / (1 / tanβ - μ)) / 2.

[0084] Furthermore, as Figure 3 shown, in step S5, the electronic control unit also obtains the thickness of the starting sewing part 11 of the sewing material to be sewn, and the electronic control unit controls the action amplitude of the pressure adjustment driving source 40 according to the thickness of the starting sewing part 11 of the sewing material to be sewn, so that the magnitude of the starting sewing target presser foot pressure is adapted to the thickness of the starting sewing part 11 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 30, 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 11 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 20 and moves synchronously with the presser foot lever 20. Of course, in other embodiments, the thickness of the starting sewing part 11 can also be manually input.

[0085] Furthermore, the electronic control unit pre-stores a seam start control mapping table as shown in Table 1 below. The seam start control mapping table includes multiple sets of mapping relationships, each set of mapping relationships includes a one-to-one corresponding thickness H of the seam start position 11 of the sewing material to be sewn. n , Target presser foot pressure at start of sewing F1 n , and the output value A of the pressure regulating driving source 40 n Thus, in step S5, the electronic control unit obtains the thickness H of the seam starting point 11 of the sewing material to be sewn. n Afterwards, according to the thickness H of the seam starting position 11 of the sewing material to be sewn n The mapping relationship determines the corresponding target presser foot pressure F1 for starting sewing n , so that the thrust provided by the presser foot 30 cannot push away the sewing material to be sewn; according to the target presser foot pressure F1 n The mapping relationship determines the motor rotation angle A of the corresponding pressure regulating driving source 40 n The electronic control unit controls the pressure regulating driving source 40 to output the rotation angle value, and reduces the current presser foot pressure of the sewing machine to the corresponding F1 n .

[0086] Table 1 Seam start control mapping table

[0087]

[0088] In summary, the seam start control method based on adjusting the presser foot pressure involved in the present application changes the presser foot pressure in the seam start stage when sewing thick materials, and automatically adjusts the presser foot pressure in the seam start stage to the target presser foot pressure for seam start, and the target presser foot pressure for seam start is adaptive to the thickness of the seam start part 11 of the sewing material to be sewn, so as to prevent the undesirable phenomenon that the thick material is pushed away by the presser foot 30 when sewing. After the seam start is completed, the current presser foot pressure is automatically restored to a normal value to meet the requirements of normal sewing. The seam start control method broadens the adaptability of the sewing machine to the sewing of thick materials, and is well adapted to the sewing process of sewing thick materials.

[0089] After the sewing machine enters the normal sewing process, the sewing will be over-stitched in the middle of sewing. Figure 10 As shown, when the presser foot 30 passes over the stem 12 of the material to be sewn, the friction coefficient may be reduced due to the stem 12 being too thick or the material being hairy, causing the feed dog 110 to be unable to provide sufficient cloth feeding force, resulting in the feed dog 110 spinning in place and failing to pass through the stem or not passing through the stem smoothly, which in turn causes the stitch length to become denser. At this time, some sewing workers will slightly lift the presser foot 30 with their knees to assist in feeding when passing through the stem, but manual methods will inevitably require a speed reduction, which increases the difficulty of operation and easily reduces the work effect. Based on the feature of the adjustable pressure of the sewing machine presser foot in the present application, the present application can provide a stem passing control method to ensure smooth stem passing.

[0090] likeFigure 9 As shown, the method for controlling the pressure drop based on adjusting the presser foot pressure provided in the present application includes the following steps in sequence.

[0091] Step P1, the electronic control unit receives a signal of passing the sewing seam; for example: the electronic control unit determines that there is a sewing seam position 12 according to the feedback of the sewing material thickness detection sensor, and the sewing seam needs to be passed.

[0092] Step P2, the electronic control unit controls the pressure regulating driving source 40 to operate, and the pressure regulating driving source 40 drives the pressure regulating rod 50 to move upward through the pressure regulating transmission unit 70, and adjusts the pressure applied by the pressure regulating spring 60 to the presser foot rod 20 and the presser foot 30 from the normal presser foot pressure to the target presser foot pressure. At this time, the force conditions of the presser foot 30 and the sewing material 12 are as follows: Figure 12 As shown in the figure; the force conditions of the presser foot 30 are: the vertical downward presser foot pressure F1 applied by the pressure-adjusting spring 60 (that is, the target presser foot pressure), the horizontal force F2 applied by the sewing machine housing, and the supporting force F3 applied by the stem 12 of the material to be sewn; the force conditions of the stem 12 of the material to be sewn are: gravity G, the pressure F4 applied by the presser foot 30, the vertical upward supporting force F5 applied by the needle plate 90, and the cloth feeding force F7; the supporting force F3 applied to the presser foot 30 and the pressure F4 applied to the stem 12 are a pair of action and reaction forces. In particular, the target presser foot pressure for passing the sewing thread should satisfy the following requirement: the horizontal component F41 of the pressure F4 applied by the presser foot 30 on the thread position 12 of the sewing material is not greater than the cloth feeding force F7, so as to reduce the resistance of the raised corner part of the presser foot 30 to the cloth feeding by reducing the presser foot pressure without increasing the cloth feeding force F7, so that the thread position 12 can be smoothly fed into the space between the presser foot 30 and the needle plate 90, thereby achieving smooth passing of the thread position.

[0093] Step P3, the sewing machine continues to sew until the presser foot 30 climbs up to the stem position 12 of the sewing material to be sewn, and the presser foot 30 is just above the stem position 12. Figure 11 As shown, it is determined that the upper stem is finished.

[0094] Step P4, the electronic control unit controls the pressure regulating driving source 40 to reset, the pressure regulating rod 50 moves downward and resets, and the presser foot pressure of the sewing machine returns to the normal presser foot pressure.

[0095] Step P5: The sewing machine continues to sew.

[0096] Furthermore, by controlling the target pressure of the presser foot passing the stem, the horizontal component F41 of the pressure F4 applied by the presser foot 30 to the stem position 12 of the sewing material to be sewn is less than or equal to the cloth feeding force F7, so that the target pressure of the presser foot passing the stem has a maximum value. At the same time, in order to prevent the feed dog 110 and the sewing material from slipping, the target pressure of the presser foot passing the stem cannot be too small, and the target pressure of the presser foot passing the stem has a minimum value. The range of the target pressure of the presser foot passing the stem in this application is as follows.

[0097] First, according to F41 ≤ F7, it is determined that there is a maximum value for the over-stem target presser foot pressure: F41 = F4 * cosβ = F1 / tanβ, F1 / tanβ ≤ F7, F1 ≤ F7 * tanβ, so the maximum value of the over-stem target presser foot pressure is F7 * tanβ.

[0098] Secondly, in order to ensure no slippage between the feed dog 110 and the sewing material to be sewn, it is necessary to satisfy: f - F4 * cosβ = f - F1 / tanβ ≥ m.a. Where f is the maximum cloth feeding force of the feed dog 110, which has a non-linear positive correlation with the presser foot pressure F1. The cloth feeding force of the feed dog 110 first increases rapidly, then slowly increases, and finally remains basically unchanged as the presser foot pressure increases; a is the maximum acceleration of the feed dog 110 in the horizontal direction at the over-stem rotation speed; m is the mass of the sewing material stem position 12 to be sewn. In this way, the minimum value X of F1 is obtained, which is the minimum value X of the over-stem target presser foot pressure. In this application, the minimum value X of the over-stem target presser foot pressure is pre-stored in the electronic control unit and is a set value.

[0099] In this way, the value range of the over-stem target presser foot pressure is: X ≤ F1 ≤ F7 * tanβ.

[0100] The over-stem target presser foot pressure is preferably taken as the intermediate value within its value range. That is, at the thickness of a certain sewing material stem position 12 to be sewn, the over-stem target presser foot pressure F1 is: F1 = (X + F7 * tanβ) / 2.

[0101] Furthermore, as Figure 9 shown, in step P1, after receiving the over-stem signal, the electronic control unit obtains the thickness of the sewing material stem position 12 to be sewn according to the feedback of the sewing material thickness detection sensor, and controls the action amplitude of the pressure adjustment drive source 40 according to the thickness of this stem position 12, so that the magnitude of the over-stem target presser foot pressure is adapted to the thickness of the sewing material stem position 12 to be sewn. Of course, in other embodiments, the thickness of the stem position 12 can also be manually input.

[0102] Preferably, the electronic control unit pre-stores an over-stem control mapping table as shown in Table 2 below. The over-stem control mapping table includes multiple groups of mapping relationships, and each group of mapping relationships includes the thickness W n of the sewing material stem position 12 to be sewn, the over-stem target presser foot pressure F1 n and the output value A n of the pressure adjustment drive source 40 that correspond one by one. In this way, after the electronic control unit obtains the thickness W n of the sewing material stem position 12 to be sewn, it determines the corresponding over-stem target presser foot pressure F1 n according to the mapping relationship where the thickness W n is located, and according to the over-stem target presser foot pressure F1 nThe mapping relationship determines the motor rotation angle A of the corresponding pressure regulating driving source 40 n The electronic control unit controls the pressure regulating driving source 40 to output the rotation angle value, and adjusts the current presser foot pressure of the sewing machine to the corresponding F1 n .

[0103] Table 2 Overshoot control mapping table

[0104]

[0105] Therefore, the present application relates to a method for controlling the sewing process based on adjusting the presser foot pressure. When sewing ...

[0106] In addition, the seam start control mapping table and the stem pass control mapping table can be combined into one control mapping table.

[0107] In summary, the present invention effectively overcomes various shortcomings of the prior art and has high industrial utilization value.

[0108] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may 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 a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A seam control method based on adjusting the pressure of the presser foot, 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 sewing machine housing, a presser foot installed at the lower end of the presser foot rod, and a presser foot pressure regulating mechanism, wherein the presser foot pressure regulating mechanism comprises a pressure regulating driving source, a pressure regulating transmission unit, a pressure regulating rod movably supported in the sewing machine housing, and a pressure regulating spring, wherein the pressure regulating driving source is connected to the pressure regulating rod through the pressure regulating transmission unit, the upper and lower ends of the pressure regulating spring are connected to the pressure regulating rod and the presser foot rod respectively, and the pressure regulating driving source is connected to the electronic control unit for communication; 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 at the beginning of sewing the first stitch, the electronic control unit controls the pressure regulating driving source to move, and the pressure regulating driving source drives the pressure regulating rod to move through the pressure regulating transmission unit, so as to adjust the pressure applied by the pressure regulating spring to the presser foot rod and the presser foot to the target presser foot pressure at the beginning of sewing; Under the action of the seam start target presser foot pressure, the presser foot is pressed against the seam start position of the sewing material to be sewn, and the horizontal component of the pressure applied by the presser foot to the seam start position of the sewing material to be sewn is not greater than the maximum static friction between the seam start position of the sewing material to be sewn and the sewing machine needle plate; S6, after the set number of stitches is completed, the electronic control unit controls the pressure regulating driving source to reset, and the pressure regulating rod to reset; S7: the sewing machine continues sewing.

2. The seam start control method based on adjusting the presser foot pressure 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 action amplitude of the pressure-adjusting driving source according to the thickness of the seam starting part of the sewing material to be sewn, so that the size of the seam starting target presser foot pressure 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 adjusting the presser foot pressure 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 adjusting the presser foot pressure 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 presser foot pressure, and the output value of the pressure regulating driving 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, it controls the action amplitude of the pressure regulating driving source 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 adjusting the presser foot pressure according to claim 1 or 2, characterized in that: The target presser foot pressure at the start of seaming is: (F+G*μ / (1 / tanβ-μ)) / 2; Wherein, F is the minimum presser foot pressure value and is the set value, G is the gravity of the seam starting part of the sewing material to be sewn, μ is the friction coefficient between the seam starting part of the sewing material to be sewn and the sewing machine needle plate, and β is the angle between the pressure applied by the presser foot on the seam starting part of the sewing material to be sewn and the horizontal plane.

6. The seam start control method based on adjusting the presser foot pressure according to claim 1, characterized in that: The pressure regulating transmission unit includes an adjusting crank, a first connecting rod, a first rocker arm with a fixed rotating fulcrum, a second connecting rod, a second rocker arm with a fixed rotating fulcrum, a third connecting rod, a third rocker arm with a fixed rotating fulcrum, a transmission slider, and a slider seat. The adjusting crank is connected to a pressure regulating driving source and is driven to rotate by the pressure regulating driving source. The two ends of the first connecting rod are respectively hinged to the adjusting crank and the first rocker arm, the two ends of the second connecting rod are respectively hinged to the first rocker arm and the second rocker arm, the two ends of the third connecting rod are respectively hinged to the second rocker arm and the third rocker arm, the transmission slider is hinged to the third rocker arm, a horizontal sliding groove that slidably cooperates with the transmission slider is provided in the slider seat, the transmission slider is abutted against the upper groove wall and the lower groove wall of the horizontal sliding groove, and the slider seat is fixed on the pressure regulating rod.

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

8. The seam start control method based on adjusting the presser foot pressure according to claim 1, characterized in that: A spring guide rod is inserted in the pressure regulating rod, the pressure regulating spring is sleeved on the spring guide rod, and the upper end thereof abuts against the pressure regulating rod; a pressure block is fixed on the presser foot rod, the lower end of the pressure regulating spring is sleeved on the top of the presser foot rod, and abuts against the pressure block.

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