Presser foot lifting method

Abstract

The invention relates to a presser foot lifting method, which comprises the following steps of: a, acquiring an area where a rotor of a main shaft motor is located when the main shaft motor stops, and dividing the rotating track of the rotor into at least two areas along the rotating direction of the rotor; b, according to the area where the rotor is located and the lifting comparison table, a presser foot lifting motor is controlled to drive the presser foot to be lifted, the areas in the lifting comparison table are the areas divided by the rotation track of the rotor in the rotation direction of the rotor, and the areas correspond to different lifting heights. According to the method, the lifting height, the area where the rotor is located and the position of a machine needle are associated by obtaining the area where the rotor is located when the spindle motor stops and matching with a lifting comparison table, and the lifting height of a presser foot driven by a presser foot lifting motor is also different according to different areas where the rotor is located when the spindle motor stops, different positions of the machine needle and different lifting heights of the presser foot driven by the presser foot lifting motor when the spindle motor stops. Therefore, the lifting height of the presser foot is automatically changed along with the change of the position of the needle, and the situation that the presser foot is interfered with the needle due to the overlarge lifting height is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of overlock sewing machines, and particularly to a method for lifting a presser foot. Background Art

[0002] When lifting the presser foot of an overlock sewing machine, the sewing needle is usually adjusted to the needle stop position first, that is, the curved needle and the needle clamp head are adjusted to the highest position, so as to avoid the situation that the curved needle or the needle clamp head is too low when lifting the presser foot, resulting in collision interference between the presser foot and the curved needle or the needle clamp head when lifting the presser foot.

[0003] However, if due to the operator's omission or some other reasons, the operator fails to adjust the sewing needle to the needle stop position when lifting the presser foot, and at this time the curved needle or the needle clamp head happens to stop at a lower position, collision interference may occur between the presser foot and the curved needle or the needle clamp head after the presser foot height is increased. Summary of the Invention

[0004] Based on this, in view of the problem that there is collision interference between the presser foot and the curved needle or the needle clamp head when lifting the presser foot of the current overlock sewing machine, it is necessary to provide a method for lifting the presser foot.

[0005] The present application provides a method for lifting a presser foot, including the steps of:

[0006] a. Obtain the area where the rotor of the main shaft motor is located when the main shaft motor stops, wherein the rotation trajectory of the rotor is divided into at least two areas along its rotation direction;

[0007] b. Control the presser foot lifting motor to drive the presser foot to lift by means of the area where the rotor is located and the lift ratio table, wherein the areas in the lift ratio table are the areas into which the rotation trajectory of the rotor is divided along its rotation direction, and different areas correspond to different lift heights.

[0008] In one embodiment, in the lift ratio table of step b:

[0009] The area includes a needle stop area and an avoidance area; in the needle stop area, the presser foot lifting motor drives the presser foot to lift by a first lift height; in the avoidance area, the presser foot lifting motor drives the presser foot to lift by a second lift height; the first lift height is greater than the second lift height.

[0010] In one embodiment, the rotor of the main shaft motor further has a needle stop position, and in the lift ratio table of step b:

[0011] The needle stop position is located in the needle stop area; when the rotor rotates to the needle stop position, the curved needle and the needle clamp head are at the highest point.

[0012] In one embodiment, the rotation trajectory of the rotor is evenly divided into 24 intervals along its rotation direction, and in the lift ratio table of step b:

[0013] Each of the said regions corresponds to at least one of the said intervals. Wherein, the needle stop position is zero point, the 1st and the 19th - 24th intervals correspond to the needle stop region, and the 2nd - 18th intervals correspond to the avoidance region.

[0014] In one embodiment, in the lifting comparison table of step b:

[0015] The avoidance region includes a bent needle avoidance region and a needle chuck avoidance region, and the two correspond to different lifting heights; the region where the rotor is located when the bent needle is at the lowest point is the bent needle avoidance region, and the region where the rotor is located when the needle chuck is at the lowest point is the needle chuck avoidance region.

[0016] In one embodiment, in the lifting comparison table of step b:

[0017] The avoidance region includes two bent needle avoidance regions and one needle chuck avoidance region, and the needle chuck avoidance region is located between the two bent needle avoidance regions.

[0018] In one embodiment, the rotor of the main shaft motor also has a needle stop position; when the rotor rotates to the needle stop position, the bent needle and the needle chuck are located at the end far from the presser foot; the rotation trajectory of the rotor is evenly divided into 24 intervals along its rotation direction. In the lifting comparison table of step b:

[0019] Each of the said regions corresponds to at least one of the said intervals. Wherein, the needle stop position is zero point, the 1st and the 19th - 24th intervals correspond to the needle stop region, the 2nd - 4th and 8th - 18th intervals correspond to the bent needle avoidance region, and the 5th - 7th intervals correspond to the needle chuck avoidance region.

[0020] In one embodiment, in the lifting comparison table of step b:

[0021] The lifting height corresponding to the bent needle avoidance region is greater than the lifting height corresponding to the needle chuck avoidance region.

[0022] In one embodiment, in the lifting comparison table of step b:

[0023] The lifting height corresponding to the bent needle avoidance region is 7 mm, the lifting height corresponding to the needle chuck avoidance region is 6 mm, and the lifting height corresponding to the needle stop region is 10 mm.

[0024] In one embodiment, the main shaft motor is a Hall motor or a servo motor.

[0025] The above presser foot lifting method obtains the area where the rotor is located when the main shaft motor stops, and combines with the lifting comparison table to associate the lifting height, the area where the rotor is located, and the position of the sewing needle (the positions of the bent needle and the needle clamp head). According to the different areas where the rotor is located when the main shaft motor stops, the position of the sewing needle is different, and the lifting height of the presser foot driven by the presser foot lifting motor is also different, so that the lifting height of the presser foot automatically changes with the change of the position of the sewing needle, thereby avoiding the situation of interference between the presser foot and the sewing needle caused by too large a lifting height of the presser foot. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic flow chart of the presser foot lifting method of the present application;

[0027] Figure 2 It is the lifting comparison table in the presser foot lifting method of the present application;

[0028] Figure 3 It is an enlarged structural schematic diagram of the position of the sewing needle of the overlock sewing machine;

[0029] Figure 4 It is a three-dimensional structural schematic diagram of the handwheel and the main shaft motor part of the overlock sewing machine;

[0030] Figure 5 It is a schematic diagram in which the rotor trajectory of the main shaft motor in the presser foot lifting method of the present application is evenly divided into 24 intervals.

[0031] Reference numerals: 11, main shaft motor; 12, bent needle; 13, needle clamp head; 14, handwheel; 21, presser foot lifting motor; 22, presser foot. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention will be given with reference to the accompanying drawings. Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0033] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the present invention.

[0034] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying 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 of such features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0035] In the present invention, unless otherwise clearly specified and defined, the terms "mounted", "connected", "coupled", "fixed", etc. shall be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0037] It should 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 can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are only for the purpose of illustration and do not represent the only implementation.

[0038] Please refer to Figures 1 to 4 As shown, the present application provides a presser foot lifting method, including the steps:

[0039] S100. Obtain the area where the rotor of the main shaft motor 11 is located when the main shaft motor 11 stops. Among them, the rotation trajectory of the rotor is divided into at least two areas along its rotation direction;

[0040] S200. Control the lifting presser foot motor 21 to drive the presser foot 22 to lift by means of the area where the rotor is located and the lift ratio table. Among them, the areas in the lift ratio table are the areas divided by the rotation trajectory of the rotor along its rotation direction, and different areas correspond to different lifting heights.

[0041] The rotation of the rotor of the main shaft motor 11 can drive the sewing needle (curved needle 12 and needle clamp 13) to perform periodic cyclic activities. Therefore, the position information of the sewing needle is related to the position of the rotor on its own rotation trajectory.

[0042] In the present application, by obtaining the area where the rotor is located when the main shaft motor 11 stops and cooperating with the lift ratio table, the three factors of the lifting height, the area where the rotor is located, and the position of the sewing needle (the positions of the curved needle 12 and the needle clamp 13) are associated. According to the different areas where the rotor is located when the main shaft motor 11 stops, the position of the sewing needle is different, and the lifting height of the lifting presser foot motor 21 driving the presser foot 22 is also different, so that the lifting height of the presser foot 22 automatically changes with the change of the position of the sewing needle, thereby avoiding the situation of interference between the presser foot 22 and the sewing needle caused by too large a lifting height of the presser foot 22.

[0043] The lifting height corresponding to each area in the lift ratio table is determined by the lower one of the positions of the curved needle 12 and the needle clamp 13 after the rotor stops at the corresponding position. As long as the lifting height is less than the height of the lower one, the situation of interference after the presser foot 22 is lifted can be avoided.

[0044] Specifically, when the main shaft motor 11 stops, the main shaft motor 11 can identify the area where the rotor stops; and since the main shaft motor 11 is electrically connected to the lifting presser foot motor 21, the main shaft motor 11 can transmit this signal to the lifting presser foot motor 21, and the lifting presser foot motor 21 drives the presser foot 22 to lift according to the preset lifting height in the lift ratio table.

[0045] Of course, in some other embodiments, the identification of the rotor stop position and the signal transmission between the main shaft motor 11 and the presser foot lifting motor 21 can also be achieved by other common methods, as long as the area where the rotor of the main shaft motor 11 is located when the main shaft motor 11 stops can be obtained and the signal can be transmitted to the presser foot lifting motor 21. The present application does not make further limitations here.

[0046] Please refer to Figure 2 and Figure 5 As shown, in some embodiments, in the lifting comparison table of step S200: the area includes a needle stop area and an avoidance area; in the needle stop area, the presser foot lifting motor 21 drives the presser foot 22 to lift by a first lifting height; in the avoidance area, the presser foot lifting motor 21 drives the presser foot 22 to lift by a second lifting height; the first lifting height is greater than the second lifting height.

[0047] The rotor of the main shaft motor 11 also has a needle stop position. In the lifting comparison table of step S200: the needle stop position is located within the needle stop area; when the rotor rotates to the needle stop position, the curved needle 12 and the needle clamp head 13 are at the highest points.

[0048] Since the needle stop position is located within the needle stop area, when the rotor is within the needle stop area, the positions of the curved needle 12 and the needle clamp head 13 are relatively high, and even if the lifting height of the presser foot 22 is relatively large, there will be no interference with the curved needle 12 and the needle clamp head 13; conversely, when the rotor is within the avoidance area, the positions of the curved needle 12 and the needle clamp head 13 are relatively low. By restricting the first lifting height to be greater than the second lifting height, it is possible to prevent the presser foot 22 from lifting excessively, thereby avoiding the situation of interference with the curved needle 12 or the needle clamp head 13.

[0049] In addition, after the main shaft motor 11 stops, the position of the main shaft motor 11 can be actively adjusted by rotating the handwheel 14. By actively adjusting the rotor into the needle stop area, a relatively high lifting height can be obtained when lifting the presser foot 22 to meet the normal requirements for lifting the presser foot.

[0050] In some embodiments, if the main shaft motor 11 is a Hall motor, the needle stop position can be determined by the cooperation of the magnet on the handwheel 14 and the needle stop Hall plate on the main shaft motor 11.

[0051] In some other embodiments, if the main shaft motor 11 is a servo motor, the needle stop position can be directly determined by the encoder connected to the servo motor.

[0052] Please refer to Figure 2 and Figure 5 As shown, in some embodiments, the rotation trajectory of the rotor is divided into 24 intervals along its rotation direction. In the lifting comparison table of step S200: each area corresponds to at least one interval, where the needle stop position is zero, the 1st and the 19th - 24th intervals correspond to the needle stop area, and the 2nd - 18th intervals correspond to the avoidance area.

[0053] By equally dividing the rotation trajectory of the rotor into a certain number of intervals along its rotation direction and corresponding each area in the lift ratio table to the intervals, the needle stop area and the avoidance area can be divided relatively accurately. Of course, it can be understood that the more the number of equally divided intervals, the more precise the area division can be obtained.

[0054] Taking the Hall motor with 8 poles of the main shaft motor 11 as an example, it has 3 Hall elements and 8 permanent magnets. Therefore, after the rotor rotates, 24 equally divided intervals can be formed. Usually, 24 equally divided intervals can already meet the requirement of clearly dividing the needle stop area and the avoidance area.

[0055] Of course, the main shaft motor 11 can also select Hall motors or servo motors with other pole numbers, and the corresponding number of intervals can also be changed according to different motor properties, as long as it is ensured that each area in the lift ratio table can correspond to the intervals.

[0056] Among them, when the main shaft motor 11 is a servo motor, the division between each area and the needle stop position are controlled by the encoder signal connected to the servo motor, and more precise control can be achieved.

[0057] Please refer to Figure 2 As shown, in some embodiments, in the lift ratio table of step S200: the avoidance area includes a loop needle avoidance area and a needle clamp head avoidance area, and the two correspond to different lift heights; the area where the rotor is located when the loop needle 12 is at the lowest point is the loop needle avoidance area, and the area where the rotor is located when the needle clamp head 13 is at the lowest point is the needle clamp head avoidance area.

[0058] It can be understood that the movement trajectory of the loop needle 12 is roughly elliptical, while the movement trajectory of the needle clamp head 13 is reciprocating up and down. The movement trajectories of the two are not related, so the positions of the rotor when the two move to the lowest point are also different. By dividing the avoidance area into a loop needle avoidance area and a needle clamp head avoidance area and presetting the lift heights respectively in the lift ratio table, it can ensure that the presser foot 22 will not interfere with the loop needle 12 and the needle clamp head 13 when lifting, and at the same time, increase the lift height of the presser foot 22 as much as possible when the rotor is in the avoidance area.

[0059] Please refer to Figure 2 and Figure 5 As shown, in some embodiments, in the lift ratio table of step S200: the avoidance area includes two loop needle avoidance areas and one needle clamp head avoidance area, and the needle clamp head avoidance area is located between the two loop needle avoidance areas.

[0060] Of course, according to the different structures of the overlock sewing machine, the number and distribution methods of the loop needle avoidance area and the needle clamp head avoidance area may be different, and the present application does not make further limitations here.

[0061] Please refer to Figure 2 and Figure 5 As shown, in some embodiments, the rotor of the main shaft motor 11 further has a needle stop position; when the rotor rotates to the needle stop position, the bent needle 12 and the needle clamp head 13 are located at one end far from the presser foot 22; the rotation trajectory of the rotor is divided into 24 intervals along its rotation direction. In the lift comparison table of step S200: each area corresponds to at least one interval, where the needle stop position is the zero point, the 1st and 19th - 24th intervals correspond to the needle stop area, the 2nd - 4th and 8th - 18th intervals correspond to the bent needle avoidance area, and the 5th - 7th intervals correspond to the needle clamp head avoidance area.

[0062] Of course, depending on the different structures of the overlock sewing machine, the number and distribution method of the intervals corresponding to each area may be different, and the present application does not make further limitations here.

[0063] Please refer to Figure 2 As shown, in some embodiments, in the lift comparison table of step S200: the lift height corresponding to the bent needle avoidance area is greater than the lift height corresponding to the needle clamp head avoidance area.

[0064] Generally, the lowest position of the bent needle 12 is higher than the lowest position of the needle clamp head 13. Therefore, designing the corresponding lift heights in the lift comparison table in this way can, while ensuring that the presser foot 22 does not interfere with the bent needle 12 and the needle clamp head 13 when lifting, increase the lift height of the presser foot 22 as much as possible when the rotor is in the bent needle avoidance area and the needle clamp head avoidance area.

[0065] Please refer to Figure 2 As shown, in some embodiments, in the lift comparison table of step S200: the lift height corresponding to the bent needle avoidance area is 7 mm, the lift height corresponding to the needle clamp head avoidance area is 6 mm, and the lift height corresponding to the needle stop area is 10 mm.

[0066] In some other embodiments, the lift heights corresponding to each area in the lift comparison table can also be other values, as long as it can be ensured that when the main shaft motor 11 rotates the rotor to be in this area, the presser foot 22 will not interfere with the bent needle 12 and the needle clamp head 13 after lifting the corresponding height according to the lift comparison table. The present application does not make further limitations here.

[0067] Please refer to Figure 3 As shown, in some embodiments, a cam 23 is connected to the presser foot lifting motor 21. According to the different areas where the rotor is located, the rotation angle of the output shaft of the presser foot lifting motor 21 is different, and the height of the presser foot 22 lifted by the cam 23 through the corresponding transmission structure is also different.

[0068] In some other embodiments, the presser foot lifting motor 21 may also be drivingly connected to the presser foot 22 through other transmission structures, as long as the presser foot lifting motor 21 can drive the presser foot 22 to lift the corresponding lifting height according to the area where the rotor is located.

[0069] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0070] The above-described embodiments only represent several implementation manners of the present invention, and the description thereof is relatively specific and detailed, but it should not be understood as a limitation to the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A presser foot lifting method, characterized in that, it includes the steps of: a. Obtain the area where the rotor of the main shaft motor is located when the main shaft motor stops, wherein the rotation trajectory of the rotor is divided into at least two areas along its rotation direction; b. Control the presser foot lifting motor to drive the presser foot to lift by means of the area where the rotor is located and the lift ratio table, wherein the areas in the lift ratio table are the areas divided by the rotation trajectory of the rotor along its rotation direction, and different areas correspond to different lift heights.

2. The presser foot lifting method according to claim 1, characterized in that, in the lift ratio table of step b: the areas include a needle stop area and an avoidance area; in the needle stop area, the presser foot lifting motor drives the presser foot to lift by a first lift height; in the avoidance area, the presser foot lifting motor drives the presser foot to lift by a second lift height; the first lift height is greater than the second lift height.

3. The presser foot lifting method according to claim 2, characterized in that, the rotor of the main shaft motor further has a needle stop position, and in the lift ratio table of step b: the needle stop position is located in the needle stop area; when the rotor rotates to the needle stop position, the curved needle and the needle clamp head are at the highest point.

4. The presser foot lifting method according to claim 3, characterized in that, the rotation trajectory of the rotor is evenly divided into 24 intervals along its rotation direction, and in the lift ratio table of step b: each area corresponds to at least one interval, wherein the needle stop position is zero, the 1st and 19th - 24th intervals correspond to the needle stop area, and the 2nd - 18th intervals correspond to the avoidance area.

5. The presser foot lifting method according to claim 2, characterized in that, in the lift ratio table of step b: the avoidance area includes a curved needle avoidance area and a needle clamp head avoidance area, and the two correspond to different lift heights; the area where the rotor is located when the curved needle is at the lowest point is the curved needle avoidance area, and the area where the rotor is located when the needle clamp head is at the lowest point is the needle clamp head avoidance area.

6. The presser foot lifting method according to claim 5, characterized in that, in the lift ratio table of step b: the avoidance area includes two curved needle avoidance areas and one needle clamp head avoidance area, and the needle clamp head avoidance area is located between the two curved needle avoidance areas.

7. The presser foot lifting method according to claim 6, characterized in that, the rotor of the main shaft motor further has a needle stop position; when the rotor rotates to the needle stop position, the curved needle and the needle clamp head are at the end far from the presser foot; the rotation trajectory of the rotor is evenly divided into 24 intervals along its rotation direction, and in the lift ratio table of step b: each area corresponds to at least one interval, wherein the needle stop position is zero, the 1st and 19th - 24th intervals correspond to the needle stop area, the 2nd - 4th and 8th - 18th intervals correspond to the curved needle avoidance area, and the 5th - 7th intervals correspond to the needle clamp head avoidance area.

8. The presser foot lifting method according to claim 5, characterized in that, in the lift ratio table of step b: The lifting height corresponding to the bent needle avoidance area is greater than the lifting height corresponding to the needle chuck avoidance area.

9. The presser foot lifting method according to claim 8, characterized in that in the lifting comparison table of step b: the lifting height corresponding to the bent needle avoidance area is 7 mm, the lifting height corresponding to the needle chuck avoidance area is 6 mm, and the lifting height corresponding to the needle stop area is 10 mm.

10. The presser foot lifting method according to claim 1, characterized in that the main shaft motor is a Hall motor or a servo motor.

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