Variable speed control method for rotating shuttle

Abstract

The invention provides a rotating shuttle variable speed control method. The method sequentially comprises the following steps that a main driving source for driving thorn cloth and a thread hooking driving source for driving thread hooking are arranged in a sewing machine; the operation rule of the main driving source and the operation rule of the thread hooking driving source are set in the main control unit, so that the rotating speed ratio of the main shaft to the rotating shuttle is 1: 1; within the range that the rotating shuttle rotates by one circle, the rotating speed of the rotating shuttle sequentially comprises a first acceleration area, a speed reduction area and a second acceleration area, and the rotating angles of the rotating shuttle comprise the rotating shuttle starting point rotating angle 0 degree, the rotating shuttle thread-off rotating angle gamma and the rotating shuttle end point rotating angle 360 degrees; within the range that the main shaft rotates by one circle, the rotating angles of the main shaft comprise the main shaft starting point rotating angle 0 degree, the main shaft off-line rotating angle phi and the main shaft end point rotating angle 360 degrees, and the rotating shuttle off-line rotating angle gamma is larger than or equal to the main shaft off-line rotating angle phi. The working load of the rotating shuttle can be reduced, and the service life of the rotating shuttle is greatly prolonged; the matching time sequence of the rotating shuttle and the machine needle can be automatically adjusted, and the thin and thick material adaptability of the sewing machine is improved.

Description

Technical Field

[0001] The invention relates to the technical field of sewing machines, and in particular to a rotary hook speed change control method. Background Art

[0002] In the existing sewing machine, the cloth-piercing mechanism and the thread-hooking mechanism share a driving source, which is the main motor of the sewing machine. Figure 1 As shown, the main shaft 10 in the sewing machine is connected to the main motor and driven to rotate by the main motor; the piercing mechanism 20 is connected to the left end of the main shaft 10, and the main motor drives the piercing mechanism 20 to operate through the main shaft 10, driving the needle 21 at the end of the piercing mechanism 20 to move up and down; at the same time, the main shaft 10 is connected to the thread hooking mechanism 30 through a set of first gear sets 100, a vertical shaft 200 extending up and down, and a set of second gear sets 300. The main shaft 10 drives the thread hooking mechanism 30 to operate through the first gear set 100, the vertical shaft 200 and the second gear set 300, driving the lower shaft 32 of the thread hooking mechanism 30 and the rotary hook 31 fixed at the left end of the lower shaft 32 to rotate. In addition, the speed ratio of the piercing mechanism 20 to the thread hooking mechanism 30 is 1:2, that is, the main shaft 10 rotates one circle, the needle 21 reciprocates up and down once, and the lower shaft 32 and the rotary hook 31 rotate two circles, or in other words, the speed ratio of the main shaft 10 to the lower shaft 32 is 1:2.

[0003] During the operation of the above-mentioned existing sewing machine, the thread hooking process of the thread hooking mechanism is roughly divided into three processes: starting to hook the thread, expanding the thread loop, and de-threading. Figure 2a As shown, when the hook tip 311 of the rotary hook 31 coincides with the needle 21, the thread is hooked, and the rotation angle of the main shaft at this time is recorded as 0°; then, the needle 21 is in an upward movement state; as the needle 21 moves upward, the rotary hook 31 continuously expands the thread loop, as shown in FIG. Figure 2b to Figure 2d As shown, until the thread loop is expanded to the maximum; then, the needle 21 continues to move upward, the rotary hook 31 continues to rotate, and the thread loop is removed from the rotary hook 31, as shown in FIG. Figure 2e During the operation of the sewing machine, the rotary hook always rotates with the rotation of the main shaft; therefore, except for the above-mentioned thread hooking process, the rotary hook still rotates with the rotation of the main shaft, but the rotary hook does not participate in the formation of the stitch, that is, except for the above-mentioned thread hooking process, the rotary hook is in an idle state.

[0004] Furthermore, let the rotation angle of the main shaft be X, and the rotation angle of the rotary hook be Y. Then the function of the rotation angle Y of the rotary hook with respect to the rotation angle X of the main shaft is f(X). The function f(X) is a linear function, such as Figure 3 As shown in the figure, the rotation angle Y of the rotary hook and the rotation angle X of the main shaft satisfy the linear correspondence of 2:1. When the main shaft rotates 360° once, the rotary hook rotates twice 720°. Figure 4As shown in the figure, within the range of 720° of two rotations of the rotary hook, the working range of the rotary hook includes the effective working area P1 and the idle area P2. The effective working area P1 is the working angle of the rotary hook in the thread hooking process. The starting point and the end point of the effective working area P1 correspond to the start of thread hooking and thread de-threading, respectively. Obviously, the effective working area P1 of the rotary hook only occupies about 1 / 3 of its working range.

[0005] In summary, the existing sewing machines have the following defects:

[0006] 1. The design of the speed ratio of the main shaft 10 to the lower shaft 32 is 1:2, which requires the rotary hook to run at a high speed. For example, if the normal speed of the main shaft is 5000r / min, the speed of the rotary hook needs to reach 10000r / min. The high speed of the rotary hook makes the inside of the rotary hook easy to wear, which shortens the service life of the rotary hook.

[0007] 2. The effective working area of ​​the rotary hook only occupies about 1 / 3 of its working range, which is inefficient.

[0008] 3. The coordination relationship between the rotary hook and the needle is determined by the assembly state and cannot be adjusted independently. It needs to be manually adjusted by professionals by disassembling parts. As a result, customers cannot easily adjust the speed of the coordination timing between the rotary hook and the needle, and cannot adapt to the sewing needs of different fabrics.

[0009] 4. A first gear set and a second gear set are arranged between the driving source and the line hooking mechanism for power transmission, which has a complex structure, is easy to wear between the gears, and generates a lot of noise during operation. Summary of the invention

[0010] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a method for controlling the speed change of a rotary hook, so as to effectively reduce the rotation speed of the rotary hook.

[0011] To achieve the above object, the present invention provides a method for controlling a rotating hook speed change, the method comprising the following steps in sequence:

[0012] S1, a main driving source, a main shaft drivingly connected to the main driving source, a cloth-piercing mechanism drivingly connected to the main shaft, a thread-hooking driving source independent of the main driving source, a rotary hook drivingly connected to the thread-hooking driving source, and a main control unit are arranged in a sewing machine, wherein the main driving source and the thread-hooking driving source are both connected to the main control unit for communication;

[0013] S2. Setting the operation rules of the main driving source and the thread hooking driving source in the main control unit so that the rotation rules of the main shaft and the rotating hook meet the following conditions:

[0014] A1, the speed ratio of the main shaft to the rotary hook is 1:1;

[0015] A2. Within the range of one rotation of the rotary hook, the rotary hook is operated at a variable speed, and the rotation angle of the rotary hook includes the rotary hook starting angle 0°, the rotary hook off-line angle γ, the rotary hook working area end angle θ and the rotary hook end angle 360°, and the rotary hook working area end angle θ> the rotary hook off-line angle γ;

[0016] A3. Within the range of one rotation of the spindle, the spindle rotation angle includes the spindle starting angle 0°, the spindle off-line rotation angle φ, the spindle working area control angle α and the spindle end angle 360°, and the spindle working area control angle α> the spindle off-line rotation angle φ; and

[0017] A4. The function f(x) of the rotation angle of the rotary hook with respect to the rotation angle of the main shaft is a periodic function with a period of 360°, and the slope of the periodic function f(x) at the starting point is consistent with its slope at the end point. The function f(x) has an off-line control point and a sewing working area control point. The coordinates of the off-line control point are (φ, γ), the rotary hook off-line angle γ ≥ the main shaft off-line angle φ, the coordinates of the sewing working area control point are (α, θ), and the rotary hook working area end point angle θ > the main shaft working area control angle α.

[0018] Furthermore, in the condition A2, the variable speed operation rule of the rotary hook is:

[0019] Within the range of one rotation of the rotary hook, the rotation speed area of ​​the rotary hook includes a first forward acceleration zone, a first forward deceleration zone and a second forward acceleration zone connected in sequence, the starting speed value of the first forward acceleration zone is the same as the end speed value of the second forward acceleration zone, the rear section of the first forward acceleration zone and the front section of the first forward deceleration zone constitute a high-speed operation zone, and the rotation angle of the rotary hook corresponding to the end point of the high-speed operation zone is smaller than the end point rotation angle θ of the rotary hook working zone.

[0020] Furthermore, in the condition A2, the variable speed operation rule of the rotary hook is:

[0021] Within the range of one rotation of the rotary hook, the rotation speed area of ​​the rotary hook includes a high-speed operation area, a second forward rotation deceleration area, a reverse acceleration area, a reverse deceleration area, and a third forward rotation acceleration area that are connected in sequence. The starting speed value of the high-speed operation area is the same as the end speed value of the third forward rotation acceleration area. The rotation angle of the rotary hook corresponding to the end point of the high-speed operation area is smaller than the end point rotation angle θ of the rotary hook working area.

[0022] Furthermore, in the condition A2, the variable speed operation rule of the rotary hook is:

[0023] Within the range of one rotation of the rotary hook, the rotation speed area of ​​the rotary hook includes a fourth forward acceleration zone, a third forward deceleration zone, a low-speed operation zone, and a fifth forward acceleration zone which are connected in sequence. The starting speed value of the fourth forward acceleration zone is the same as the end speed value of the fifth forward acceleration zone. The rear end portion of the fourth forward acceleration zone and the front end portion of the third forward deceleration zone constitute a high-speed operation zone. The rotation angle of the rotary hook corresponding to the end point of the high-speed operation zone is smaller than the end point rotation angle θ of the rotary hook working zone.

[0024] Furthermore, the off-line rotation angle φ of the spindle is 110°≤φ≤225°.

[0025] Furthermore, the rotation angle value of the hook thread derailment angle γ is: 180°+μ≤γ≤230°+μ, where μ is the angle between the hook tip and the root of the thread receiving groove in the hook.

[0026] Furthermore, the wire hook driving source is a motor, an encoder is provided in the motor, the encoder includes a signal generating unit, a signal identification unit and a signal conversion unit, the signal generating unit is fixed on the motor shaft of the wire hook driving source, the signal identification unit is matched with the signal generating unit, the signal identification unit is connected to the signal conversion unit, and the signal conversion unit is connected to the main control unit.

[0027] Furthermore, the sewing machine is also provided with a rotatable lower shaft, the thread hooking driving source is a motor, one end of the lower shaft is connected to the motor shaft of the thread hooking driving source, and the rotary hook is fixed to the other end of the lower shaft.

[0028] Furthermore, the cloth-piercing mechanism includes a needle bar crank fixed on the main shaft, a needle bar connecting rod, a needle bar installed in a sewing machine housing so as to be movably installed up and down, a connecting column fixed on the needle bar, and a needle installed at the lower end of the needle bar, the needle bar crank is provided with an eccentric shaft section, and the two ends of the needle bar connecting rod are rotatably connected to the eccentric shaft section and the connecting column respectively.

[0029] As described above, the rotary hook speed change control method according to the present invention has the following beneficial effects:

[0030] In the present application, an independent thread hook driving source is used to drive the rotary hook to rotate, and the coordination of the rotary hook and the machine needle is achieved by speed control of the rotary hook, and finally the speed ratio of the main shaft and the rotary hook is 1:1. In this way, the rotation speed of the rotary hook can be reduced, which greatly reduces the workload of the rotary hook and greatly prolongs the service life of the rotary hook; and the thread hook driving source for driving the thread hook and the main driving source for driving the piercing cloth are two independently controlled driving sources, so the main control unit can adjust the action timing of the control thread hook driving source and the main driving source, and then can conveniently and autonomously adjust the coordination timing of the rotary hook and the machine needle, greatly improving the adaptability of the sewing machine to thin and thick materials and adapting to the sewing needs of different fabrics. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of an existing sewing machine.

[0032] Figure 2a to Figure 2e for Figure 1 Schematic diagram of the thread hooking process of the sewing machine.

[0033] Figure 3 for Figure 1 The relationship between the rotation angle Y of the middle hook and the rotation angle X of the main shaft.

[0034] Figure 4 for Figure 1 Schematic diagram of the working area of ​​the middle hook.

[0035] Figure 5 It is a structural schematic diagram of the sewing machine in this application.

[0036] Figure 6 This is a speed curve diagram of the first speed control method of the rotary hook in this application.

[0037] Figure 7 for Figure 6 The corresponding relationship curve between the hook angle Y and the spindle angle X.

[0038] Figure 8 This is a speed curve diagram of the second speed control method of the rotary hook in this application.

[0039] Fig. 9 for Figure 8 The corresponding relationship curve between the hook angle Y and the spindle angle X.

[0040] Fig.10 This is a speed curve diagram of the third speed control method of the rotary hook in this application.

[0041] Fig.11 for Fig.10 The corresponding relationship curve between the hook angle Y and the spindle angle X.

[0042] Fig.12 It is a schematic diagram of the structure of the rotary hook.

[0043] Fig.13 Schematic diagram of the structure of the encoder in this application.

[0044] Fig.14 This is a block diagram of the control principle between the main control unit and the hook line driving source in this application.

[0045] Fig.15 Schematic diagram of the recovery height △D.

[0046] Component number description

[0047] 10 Spindle

[0048] 20. Cloth-piercing mechanism

[0049] 21 Needle

[0050] 22 Needle bar crank

[0051] 23 Needle bar connecting rod

[0052] 24 Needle bar

[0053] 25 Connecting column

[0054] 30 Wire hook mechanism

[0055] 31 Hook

[0056] 311 shuttle tip

[0057] 312 Root of the cable trough

[0058] 32 Lower shaft

[0059] 40 Hook line drive source

[0060] 50 Encoder

[0061] 51 Signal generating unit

[0062] 52 signal recognition unit

[0063] 53 Signal conversion unit DETAILED DESCRIPTION

[0064] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0065] It should be noted that the structures, proportions, sizes, etc. drawn in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change of the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0066] It should also be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may 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 may be directly connected to the other element or may be indirectly connected to the other element through an intermediate element.

[0067] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0068] The present invention provides a rotary hook speed change control method for a sewing machine, the rotary hook speed change control method comprising the following steps in sequence:

[0069] Step S1: Figure 5 As shown, the sewing machine is equipped with a main driving source, a main shaft 10 drivingly connected to the main driving source, a piercing mechanism 20 drivingly connected to the main shaft 10, a thread hooking driving source 40 independent of the main driving source, a rotary hook 31 drivingly connected to the thread hooking driving source 40, and a main control unit. The main shaft 10 extends straightly to the left and right, and the main driving source and the thread hooking driving source 40 are both connected to the main control unit for communication. When the sewing machine is running, the main driving source drives the main shaft 10 to rotate, thereby driving the needle 21 in the piercing mechanism 20 to move up and down to perform the piercing action; the thread hooking driving source 40 drives the rotary hook 31 to rotate to perform the thread hooking action.

[0070] Step S2: Based on the fact that the main driving source and the thread hooking driving source 40 are two independent driving sources, the operation rules of the main driving source and the thread hooking driving source 40 can be set in the main control unit so that the rotation rules of the main shaft 10 and the rotation rules of the rotary hook 31 simultaneously meet the following conditions:

[0071] Condition A1: The speed ratio of the main shaft 10 and the rotary hook 31 is 1:1; that is, in one complete working cycle, the main shaft 10 and the rotary hook 31 both rotate one circle, and the rotation period of the main shaft 10 is 360°, and the rotation period of the rotary hook 31 is also 360°.

[0072] Condition A2: Based on the fact that the rotary hook 31 is driven to rotate by the independent thread hook driving source 40, within the range of 360° of one rotation of the rotary hook 31, the rotary hook 31 is set to operate at a variable speed, such as Figure 6 or Figure 8 or Fig.10 and, within the range of 360° rotation of the rotary hook 31, as shown; Figure 7 or Fig. 9 or Fig.11 As shown, the rotation angle of the rotary hook 31 includes the rotary hook starting angle 0°, the rotary hook off-line angle γ, the rotary hook working area end angle θ and the rotary hook end angle 360°, and the rotary hook working area end angle θ> the rotary hook off-line angle γ. In a single cycle of the rotary hook 31 rotating one circle, the corresponding relationship between the speed range and the rotation angle of the rotary hook 31 is: the starting point of the speed range corresponds to the rotary hook starting angle 0°, and the end point of the speed range corresponds to the rotary hook end angle 360°.

[0073] Condition A3: Figure 7 or Fig. 9 or Fig.11 As shown, within the range of 360° rotation of the spindle 10, the rotation angle of the spindle 10 includes the spindle starting angle 0°, the spindle off-line angle φ, the spindle working area control angle α and the spindle terminal angle 360°, and the spindle working area control angle α is greater than the spindle off-line angle φ; the spindle starting angle 0° is equal to the shuttle starting angle 0°, and the spindle terminal angle 360° is equal to the shuttle terminal angle 360°.

[0074] Condition A4: Let the function of the rotation angle Y of the rotary hook 31 with respect to the rotation angle X of the main shaft 10 be f(x). Then the function f(x) is a periodic function with a period of 360°, such as Figure 7 or Fig. 9 or Fig.11As shown, the curve law of each working cycle is the same. In addition, the function curve of the periodic function f(x) will pass through the following four fixed points: the starting control point A, the off-line control point B (i.e., the point where the rotary hook 31 starts to off-line), the sewing work area control point D (i.e., the point where the rotary hook 31 ends off-line) and the end control point C. The coordinates of the periodic function f(x) at the starting control point A are (0°, 0°), corresponding to the spindle starting angle 0° of the main shaft 10 and the rotary hook starting angle 0° of the rotary hook 31. The coordinates of the periodic function f(x) at the off-line control point B are (φ, γ), corresponding to the spindle off-line angle φ of the main shaft 10 and the rotary hook off-line angle γ of the rotary hook 31, and the rotary hook off-line angle γ ≥ the spindle off-line angle φ, then the rotary hook 31 starts to off-line when it runs to the rotary hook off-line angle γ. The coordinates of the periodic function f(x) at the control point D of the sewing work area are (α, θ), corresponding to the spindle work area control angle α of the main shaft 10 and the end point angle θ of the hook work area of ​​the hook 31. The end point angle θ of the hook work area is greater than the spindle work area control angle α. Then, the hook 31 stops de-threading when it runs to the end point angle θ of the hook work area. The coordinates of the periodic function f(x) at the end control point C are (360°, 360°), corresponding to the spindle end point angle 360° of the main shaft 10 and the end point angle 360° of the hook 31. Moreover, the slope of the periodic function f(x) at the starting point (i.e., the starting control point A) is consistent with its slope at the end point (i.e., the end control point C), which is recorded as f ( ' X＝0) =f ( ' X＝360) .

[0075] The sewing work area control point D refers to the end point of the hook 31 participating in sewing within the range of 360° rotation of the hook 31. That is to say, when the hook driving source 40 drives the hook 31 to rotate to the end point angle θ of the hook work area corresponding to the sewing work area control point D, the hook 31 just ends the thread break and the sewing is completed. Therefore, within the range of 360° rotation of the hook 31, [0°, θ] is the effective working area P1 of the hook 31, and [θ, 360°] is the idle area P2 of the hook 31. The hook 31 does not participate in sewing in the idle area P2.

[0076] By setting the above conditions 1 to 4, the sewing machine can complete normal sewing when the speed ratio of the main shaft 10 to the rotary hook 31 is 1:1. In this application, an independent thread hooking drive source 40 is used to drive the rotary hook 31 to rotate, and the coordination of the rotary hook 31 and the machine needle 21 is realized by the speed control of the rotary hook 31, and finally the speed ratio of the main shaft 10 and the rotary hook 31 is 1:1, so that the main shaft 10 and the rotary hook 31 rotate one circle in one working cycle. In this way, the average speed of the rotary hook 31 can be reduced, which greatly reduces the workload of the rotary hook 31 and greatly prolongs the service life of the rotary hook 31; and the thread hooking drive source 40 for driving the thread hook and the main drive source for driving the piercing cloth are two independently controlled drive sources, so the main control unit can adjust the action timing of the thread hooking drive source 40 and the main drive source, and then can conveniently and autonomously adjust the coordination timing of the rotary hook 31 and the machine needle 21, greatly improving the adaptability of the sewing machine to thin and thick materials and adapting to the sewing needs of different fabrics.

[0077] Furthermore, in this embodiment, the preferred range of the spindle off-line rotation angle φ is: 110°≤φ≤225°.

[0078] Furthermore, if Fig.12 As shown, the included angle between the hook tip 311 and the thread receiving groove root 312 of the rotary hook 31 is μ, and the value of the included angle μ depends on the model of the rotary hook 31. During the operation of the rotary hook 31, the rotary hook 31 rotates from the initial thread hooking angle 0° to the rotary hook thread-off angle γ, the angle rotated by the hook tip 311 of the rotary hook 31 is γ, and the angle rotated by the thread receiving groove root 312 of the rotary hook 31 is β, then β=γ-μ; the preferred range of β is 180°≤β≤230°, and the preferred range of the angle value corresponding to the rotary hook thread-off angle γ is: 180°+μ≤γ≤230°+μ.

[0079] Furthermore, in the above condition A2, there are multiple ways to change the speed of the rotary hook 31 so that the rotation angle of the rotary hook 31 meets the requirements of the rotary hook off-line angle γ and the rotary hook working area end angle θ. The following provides three preferred ways of changing the speed of the rotary hook 31.

[0080] Method 1: The variable speed operation rule of the rotary hook 31 in the above condition A2 is: Figure 6As shown, within the range of 360° of one rotation of the rotary hook 31, the speed region of the rotary hook 31 includes the first forward acceleration zone W1, the first forward deceleration zone W2, and the second forward acceleration zone W3 connected in sequence. The starting speed value of the first forward acceleration zone W1 is the same as the ending speed value of the second forward acceleration zone W3. The rotation direction of the rotary hook 31 in the entire cycle is the forward direction. The rear section of the first forward acceleration zone W1 and the front section of the first forward deceleration zone W2 constitute the high-speed operation zone H. The rotation angle of the rotary hook 31 corresponding to the end point of the high-speed operation zone H is smaller than the end point angle θ of the rotary hook working zone. The starting point of the first forward acceleration zone W1 corresponds to the starting angle of the rotary hook 0°, and the end point of the second forward acceleration zone W3 corresponds to the end point angle of the rotary hook 360°. The function curve of the fitted periodic function f(x) is shown as follows: Figure 7 As shown, the slope of the periodic function f(x) in the interval [0°, φ] is larger, and the slope of the periodic function f(x) in the interval [φ, 360°] is smaller.

[0081] Take the case where the main shaft 10 rotates at 5000 rpm as an example (under this condition, the rotary hook in the conventional machine is maintained at a constant speed of 10000 rpm). Figure 6 As shown, the rotary hook 31 has the highest speed at the connection of the first forward acceleration zone W1 and the first forward deceleration zone W2, and the highest speed of the rotary hook 31 is less than 10000rpm; the average speed of the rotary hook 31 is maintained at about 5000rpm; the rotary hook 31 has the lowest speed at the connection of the first forward deceleration zone W2 and the second forward acceleration zone W3, and the lowest speed of the rotary hook 31 is significantly lower than the average speed of 5000rpm. Obviously, the highest speed of the rotary hook 31 is significantly lower than 10000rpm, which is greatly reduced, thereby greatly extending the service life of the rotary hook 31.

[0082] Mode 2: The variable speed operation rule of the rotary hook 31 in the above condition A2 is: Figure 8 As shown, within the range of 360° rotation of the rotary hook 31, the rotation speed area of ​​the rotary hook 31 includes the high-speed operation area H, the second forward deceleration area W4, the reverse acceleration area W5, the reverse deceleration area W6, and the third forward acceleration area W7, which are connected in sequence. The rotation speed of the rotary hook 31 in the high-speed operation area H is maintained at about 10000*(1±25%) rpm. The starting speed value of the high-speed operation area H is the same as the end speed value of the third forward acceleration area W7. The rotation angle of the rotary hook 31 corresponding to the end point of the high-speed operation area H is smaller than the end point rotation angle θ of the rotary hook working area. The rotation direction of the rotary hook 31 in the second forward deceleration area W4 and the third forward acceleration area W7 is the forward direction, and the rotation direction of the rotary hook in the reverse acceleration area W5 and the reverse deceleration area W6 is the reverse direction. Therefore, the function curve of the fitted periodic function f(x) is as follows: Fig. 9As shown, the slope of the periodic function f(x) in the interval [0°, θ] is relatively large. In the interval [θ, 360°], the rotary hook 31 first reverses and then rotates forward to the end point of the rotary hook 360°.

[0083] from Figure 8 It can be seen that the rotary hook 31 has a relatively high rotation speed only in the high-speed operation zone H, and then the rotation speed of the rotary hook 31 gradually decreases and maintains an average rotation speed far less than 10000 rpm, thereby greatly extending the service life of the rotary hook 31.

[0084] Mode 3: The variable speed operation rule of the rotary hook 31 in the above condition A2 is: Fig.10 As shown, within the range of 360° of the rotary hook 31 rotating in one circle, the rotation speed area of ​​the rotary hook 31 includes the fourth forward acceleration zone W8, the third forward deceleration zone W9, the low-speed operation zone L, and the fifth forward acceleration zone W10, which are connected in sequence. The rotation direction of the rotary hook 31 in the entire cycle is the forward direction. The starting speed value of the fourth forward acceleration zone W8 is the same as the terminal speed value of the fifth forward acceleration zone W10. The rear end part of the fourth forward acceleration zone W8 and the front part of the third forward deceleration zone W9 constitute the high-speed operation zone H. The average speed of the rotary hook 31 in the high-speed operation zone H is maintained at about 10000*(1±25%)rpm. The rotation angle of the rotary hook 31 corresponding to the terminal point of the high-speed operation zone H is smaller than the terminal angle θ of the rotary hook working area. The function curve of the fitted periodic function f(x) is as follows: Fig.11 As shown, the slope of the periodic function f(x) in the interval [0°, θ] is relatively large, while the slope of the periodic function f(x) in the interval [θ, 360°] is relatively small and very gentle.

[0085] from Fig.10 It can be seen that the rotary hook 31 has the highest speed at the connection of the fourth forward acceleration zone W8 and the third forward deceleration zone W9, and has the lowest speed at the connection of the low-speed operation zone L and the fifth forward acceleration zone W10. Although the average speed of the rotary hook 31 in the high-speed operation zone H is maintained at about 10,000 rpm, the average speed of the rotary hook 31 in the low-speed operation zone L is maintained at about 1,000 rpm, which is much less than 10,000 rpm, so that the average speed of the rotary hook 31 in the entire cycle is maintained at about 5,000 rpm, thereby greatly extending the service life of the rotary hook 31.

[0086] Furthermore, the hooking line driving source 40 is a motor, and an encoder 50 is provided in the motor; Fig.13As shown, the encoder 50 includes a signal generating unit 51, a signal identifying unit 52 and a signal converting unit 53. The signal generating unit 51 is fixed on the motor shaft of the hooking driving source 40, and generates an angular displacement signal as the motor shaft of the hooking driving source 40 rotates; the signal identifying unit 52 matches the signal generating unit 51, can identify the above angular displacement signal, and transmit the angular displacement signal to the signal converting unit 53; the signal identifying unit 52 is connected to the signal converting unit 53, and the signal converting unit 53 is connected to the main control unit, and the signal converting unit 53 converts the above angular displacement signal into an electrical signal and transmits it to the main control unit. In this way, Fig.14 As shown, the encoder 50 feeds back the current position angle of the rotary hook 31 to the main control unit in real time, and the main control unit determines whether the current position angle of the rotary hook 31 satisfies the preset rotation law. If not, the main control unit outputs a positive voltage or a reverse voltage to the thread hooking drive source 40 through the drive circuit to correct the angle of the thread hooking drive source 40, thereby correcting the current position angle of the rotary hook 31, until the current position angle of the rotary hook 31 satisfies the preset rotation law.

[0087] Furthermore, if Figure 5 As shown, the sewing machine is also provided with a rotatable lower shaft 32, which is parallel to the main shaft 10 and extends straightly from left to right, and the rotary hook 31 and the lower shaft 32 constitute the thread hooking mechanism 30 of the sewing machine. The thread hooking driving source 40 is a motor, preferably a stepping motor, fixed on the sewing machine housing, the right end of the lower shaft 32 is fixedly connected to the motor shaft of the thread hooking driving source 40, and the rotary hook 31 is fixed to the left end of the lower shaft 32. The thread hooking driving source 40 directly drives the lower shaft 32 to rotate, and the rotary hook 31 rotates with the lower shaft 32 to hook the thread. Of course, in other embodiments, the right end of the lower shaft 32 and the motor shaft of the thread hooking driving source 40 can also be connected through a gear mechanism or a synchronous wheel mechanism.

[0088] Furthermore, the preferred structure of the piercing mechanism 20 is as follows: Figure 5 As shown, the piercing mechanism 20 includes a needle bar crank 22 fixed to the left end of the main shaft 10 by screws, a needle bar connecting rod 23, a needle bar 24 installed in the sewing machine housing so as to be movable up and down, a connecting column 25 fixed to the needle bar 24, and a needle 21 installed at the lower end of the needle bar 24. An eccentric shaft section is integrally provided on the left end surface of the needle bar crank 22, and the eccentric shaft section is eccentrically arranged with the main shaft 10. The upper end of the needle bar connecting rod 23 is hinged to the eccentric shaft section, and the lower end of the needle bar connecting rod 23 is hinged to the connecting column 25. The main driving source is a motor, preferably a stepping motor, fixed to the sewing machine housing, and the right end of the main shaft 10 is fixedly connected to the motor shaft of the main driving source. The main driving source directly drives the main shaft 10 to rotate, and the needle bar crank 22 rotates with the main shaft 10, and drives the needle bar 24 to reciprocate up and down through the eccentric shaft section, the needle bar connecting rod 23 and the connecting column 25. The machine needle 21 reciprocates up and down with the needle bar 24 to pierce the cloth.

[0089] Furthermore, the speed of the coordination timing between the rotary hook 31 and the needle 21 is usually expressed by the recovery height △D; the recovery height △D refers to: Fig.15 As shown, the state of the needle 21 when the shuttle tip 311 of the rotary hook 31 coincides with the needle 21 is recorded as state one, and the state of the needle 21 when the needle 21 is at the lowest point during the up and down reciprocating movement is recorded as state two. The height difference of the needle 21 in the vertical direction between state one and state two is the recovery height △D. The smaller the value of the recovery height △D, the faster the timing of the rotary hook 31 relative to the needle 21; the larger the value of the recovery height △D, the slower the timing of the rotary hook 31 relative to the needle 21. The present application adopts an independent hook thread drive source 40 to drive the rotary hook 31 to rotate, so the coordination timing between the rotary hook 31 and the needle 21 is adjustable, or in other words, the size of the recovery height △D can be adjusted by adjusting the speed of the rotary hook 31 drive source relative to the main drive source to meet the sewing requirements of different fabrics.

[0090] In summary, the present invention effectively overcomes various shortcomings of the prior art and has high industrial utilization value.

[0091] 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 method for controlling the speed change of a rotary hook, characterized in that: The rotary hook speed change control method comprises the following steps in sequence: S1, a main driving source, a main shaft (10) drivingly connected to the main driving source, a cloth-piercing mechanism (20) drivingly connected to the main shaft (10), a thread-hooking driving source (40) independent of the main driving source, a rotary hook (31) drivingly connected to the thread-hooking driving source (40), and a main control unit are arranged in a sewing machine, wherein the main driving source and the thread-hooking driving source (40) are both connected to the main control unit for communication; S2. The operation rules of the main driving source and the thread hooking driving source (40) are set in the main control unit so that the rotation rules of the main shaft (10) and the rotation rules of the rotary hook (31) meet the following conditions: A1, the speed ratio of the main shaft (10) and the rotary hook (31) is 1:1; A2. Within the range of one rotation of the rotary hook (31), the rotary hook (31) is operated at a variable speed, and the rotation angles of the rotary hook (31) include a rotary hook starting angle of 0°, a rotary hook off-line angle γ, a rotary hook working area end angle θ, and a rotary hook end angle of 360°, wherein the rotary hook working area end angle θ is greater than the rotary hook off-line angle γ; A3. Within the range of one rotation of the spindle (10), the rotation angle of the spindle (10) includes the spindle starting angle 0°, the spindle off-line angle φ, the spindle working area control angle α and the spindle end angle 360°, and the spindle working area control angle α is greater than the spindle off-line angle φ; and A4. The function f(x) of the rotation angle of the rotary hook (31) with respect to the rotation angle of the spindle (10) is a periodic function with a period of 360°, and the slope of the periodic function f(x) at the starting point is consistent with its slope at the end point. The function f(x) has an off-line control point and a sewing work area control point. The coordinates of the off-line control point are (φ, γ). The off-line rotation angle γ of the rotary hook is ≥ the off-line rotation angle φ of the spindle. The coordinates of the sewing work area control point are (α, θ). The end point rotation angle θ of the rotary hook work area is greater than the control angle α of the spindle work area.

2. The method for controlling the speed change of the rotary hook according to claim 1, characterized in that: In the condition A2, the variable speed operation rule of the rotary hook (31) is: Within the range of one rotation of the rotary hook (31), the rotation speed region of the rotary hook (31) includes a first forward acceleration zone (W1), a first forward deceleration zone (W2) and a second forward acceleration zone (W3) which are connected in sequence, the starting speed value of the first forward acceleration zone (W1) is the same as the ending speed value of the second forward acceleration zone (W3), the rear section of the first forward acceleration zone (W1) and the front section of the first forward deceleration zone (W2) constitute a high-speed operation zone (H), and the rotation angle of the rotary hook (31) corresponding to the end point of the high-speed operation zone (H) is smaller than the end point rotation angle θ of the rotary hook working zone.

3. The method for controlling the speed change of the rotary hook according to claim 1, characterized in that: In the condition A2, the variable speed operation rule of the rotary hook (31) is: Within the range of one rotation of the rotary hook (31), the rotation speed region of the rotary hook (31) includes a high-speed operation zone (H), a second forward rotation speed reduction zone (W4), a reverse rotation acceleration zone (W5), a reverse rotation speed reduction zone (W6), and a third forward rotation acceleration zone (W7) connected in sequence, the starting speed value of the high-speed operation zone (H) is the same as the end speed value of the third forward rotation acceleration zone (W7), and the rotation angle of the rotary hook (31) corresponding to the end point of the high-speed operation zone (H) is smaller than the end point rotation angle θ of the rotary hook working zone.

4. The method for controlling the speed change of the rotary hook according to claim 1, characterized in that: In the condition A2, the variable speed operation rule of the rotary hook (31) is: Within the range of one rotation of the rotary hook (31), the rotation speed region of the rotary hook (31) includes a fourth forward acceleration zone (W8), a third forward deceleration zone (W9), a low-speed operation zone (L), and a fifth forward acceleration zone (W10) which are connected in sequence. The starting speed value of the fourth forward acceleration zone (W8) is the same as the ending speed value of the fifth forward acceleration zone (W10). The rear end portion of the fourth forward acceleration zone (W8) and the front end portion of the third forward deceleration zone (W9) constitute a high-speed operation zone (H). The rotation angle of the rotary hook (31) corresponding to the end point of the high-speed operation zone (H) is smaller than the end point rotation angle θ of the rotary hook working zone.

5. The method for controlling the speed change of the rotary hook according to claim 1, characterized in that: The rotation angle value of the spindle off-line rotation angle φ is: 110°≤φ≤225°.

6. The method for controlling the speed change of the rotary hook according to claim 1, characterized in that: The rotation angle γ of the rotary hook thread derailment is: 180°+μ≤γ≤230°+μ, where μ is the angle between the shuttle tip (311) of the rotary hook (31) and the root (312) of the thread receiving groove.

7. The method for controlling the speed change of the rotary hook according to claim 1, characterized in that: The thread hooking driving source (40) is a motor, an encoder (50) is arranged in the motor, the encoder (50) comprises a signal generating unit (51), a signal identifying unit (52) and a signal converting unit (53), the signal generating unit (51) is fixed on the motor shaft of the thread hooking driving source (40), the signal identifying unit (52) matches the signal generating unit (51), the signal identifying unit (52) is connected to the signal converting unit (53), and the signal converting unit (53) is connected to a main control unit.

8. The method for controlling the speed change of the rotary hook according to claim 1, characterized in that: The sewing machine is also provided with a rotatable lower shaft (32), the thread hooking driving source (40) is a motor, one end of the lower shaft (32) is connected to the motor shaft of the thread hooking driving source (40), and the rotary shuttle (31) is fixed to the other end of the lower shaft (32).

9. The method for controlling the speed change of the rotary hook according to claim 1, characterized in that: The cloth-piercing mechanism (20) comprises a needle bar crank (22) fixed on a main shaft (10), a needle bar connecting rod (23), a needle bar (24) mounted in a sewing machine housing so as to be movable up and down, a connecting column (25) fixed on the needle bar (24), and a needle (21) mounted on the lower end of the needle bar (24); an eccentric shaft section is provided on the needle bar crank (22), and two ends of the needle bar connecting rod (23) are rotatably connected to the eccentric shaft section and the connecting column (25) respectively.

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