Control method for preventing needle breakage in sewing machine

Abstract

The present invention relates to the technical field of sewing machines, and in particular, to a control method for preventing needle breakage in a sewing machine. A thin material mode having a thin-material forward / reverse sewing non-switching angle range, and a thick material mode having a thick-material forward / reverse sewing non-switching angle range are set, wherein the height of a needle from the upper surface of a throat plate corresponding to the starting angle of the thick-material forward / reverse sewing non-switching angle range is greater than the height of the needle from the upper surface of the throat plate corresponding to the starting angle of the thin-material forward / reverse sewing non-switching angle range; and the ending angles of the thick-material and thin-material forward / reverse sewing non-switching angle ranges both correspond to a feed dog being lowered below the throat plate; and a fabric thickness threshold is set, wherein when the thickness of a sewn fabric does not exceed the fabric thickness threshold, a forward and reverse sewing switching operation is performed on the basis of the thin material mode, and when the thickness of the sewn fabric exceeds the fabric thickness threshold, the forward and reverse sewing switching operation is performed on the basis of the thick material mode. The present invention prevents needle breakage during sewing on thick materials, avoids an extra stitch during sewing on thin materials, and ensures a fast response during switching between forward and reverse sewing.

Description

Control method for preventing needle breakage of sewing machine TECHNICAL FIELD

[0001] The present application relates to the field of sewing machines, and particularly relates to a control method for preventing needle breakage of a sewing machine. BACKGROUND

[0002] During sewing, a sewing machine will perform a process of local reinforcement by multiple forward and reverse sewing. When the sewing machine performs forward and reverse sewing reinforcement on thick material, the instant movement of the feed dog during forward and reverse sewing switching will cause the needle to break, affecting the sewing effect.

[0003] Referring to FIG. 1, in the standard sewing mode of the prior art, the movement trajectory of the feed dog 1 is an oval shape. When a forward and reverse sewing switching instruction is received, the feed dog 1 will have an instant movement. As shown in FIGS. 1-1 and 1-2, during forward sewing, if the forward and reverse sewing switching signal is triggered when the feed dog 1 moves a distance a from the starting position A of a needle, the feed dog 1 will move to a distance a from the end position B of the needle in the next moment, and then reverse to perform reverse sewing.

[0004] Referring to FIG. 2, during sewing, there is a certain synchronization relationship between the needle 3 and the feed dog 1: when the lower edge of the needle hole of the needle 3 moves from top to bottom to the upper surface height of the needle plate 2, the feed dog 1 also moves from top to bottom to the upper surface height of the needle plate 2. Thus, during a sewing cycle, the needle 3 will pierce the fabric 4, but the feed dog 1 will be located above the needle plate 2, as shown in FIG. 3. If the forward and reverse sewing switching signal is triggered at this time, the feed dog 1 will move with the fabric 4 and pull the needle 3 that pierces the fabric 4 to break. Therefore, in the sewing control program, the needle 3 cannot trigger the forward and reverse sewing switching signal for a short period of time before piercing the needle plate 2, in order to prevent the needle from breaking during forward and reverse sewing switching. The range of the main shaft angle corresponding to this short period of time during which the forward and reverse sewing switching signal cannot be triggered is the forward and reverse sewing non-switching angle interval. When the main shaft is located at the starting angle of the forward and reverse sewing non-switching angle interval, the needle 3 has a certain height from the upper surface of the needle plate 2; as the main shaft rotates within the forward and reverse sewing non-switching angle interval, the height of the needle 3 from the upper surface of the needle plate 2 gradually decreases, and during this process, the feed dog 1 moves from top to bottom synchronously; when the main shaft rotates to the terminal angle of the forward and reverse sewing non-switching angle interval, the feed dog 1 sinks below the needle plate 2. When the forward and reverse sewing switching instruction is received, if the main shaft angle is located within the forward and reverse sewing non-switching angle interval, the forward and reverse sewing switching signal will not be triggered, and the forward and reverse sewing switching signal will be triggered after the main shaft rotates to the terminal angle of the forward and reverse sewing non-switching angle interval, so that the forward and reverse sewing switching is performed. At this time, the feed dog 1 has sunk below the needle plate 2, so the feed dog 1 will not move with the fabric 4 to pull the needle 3 that pierces the fabric 4 to break.

[0005] Referring to FIG. 4, the non-switching angle interval of the forward and reverse stitching in the prior art is about 20°-90°, and the maximum height of the needle 3 from the upper surface of the needle plate 2 is about 6mm, which is a fixed value and does not change with the change of the cloth 4. Thus, when the thickness of the cloth 4 is greater than the fixed value, the needle 3 will be inserted into the cloth 4 before the main shaft angle enters the non-switching angle interval of the forward and reverse stitching, and the feeding tooth 1 will still move with the cloth 4 to pull the needle 3 inserted into the cloth 4 when the forward and reverse stitching switching signal is triggered before the main shaft angle enters the non-switching angle interval of the forward and reverse stitching.

[0006] If the non-switching angle interval of the forward and reverse stitching is increased, the starting angle of the non-switching angle interval of the forward and reverse stitching is smaller, the maximum height of the needle 3 from the upper surface of the needle plate 2 is increased, and the maximum height m of the needle 3 from the upper surface of the needle plate 2 corresponding to the non-switching angle interval of the forward and reverse stitching is obtained, the needle 3 cannot trigger the forward and reverse stitching switching signal when it moves from top to bottom to the height m. Although this can reduce the needle breakage caused by the forward and reverse stitching switching, when sewing thin materials with small thickness, the needle 3 cannot trigger the forward and reverse stitching switching signal when it is at a position far from the thin material, and the forward and reverse stitching switching response is reduced, which affects the sewing experience of the customer. SUMMARY

[0007] In view of the above defects of the prior art, the technical problem to be solved by the present application is to provide a control method for preventing needle breakage of a sewing machine, which can adapt to different thicknesses of cloth to realize forward and reverse stitching switching and prevent needle breakage.

[0008] To solve the above technical problems, the present application adopts the following technical solutions:

[0009] The present application provides a control method for preventing needle breakage of a sewing machine, which sets a thin material mode with a non-switching angle interval of forward and reverse stitching of thin material and a thick material mode with a non-switching angle interval of forward and reverse stitching of thick material, the height of the needle from the upper surface of the needle plate corresponding to the starting angle of the non-switching angle interval of forward and reverse stitching of thick material is greater than the height of the needle from the upper surface of the needle plate corresponding to the starting angle of the non-switching angle interval of forward and reverse stitching of thin material, the ending angle of the non-switching angle interval of forward and reverse stitching of thick material and the ending angle of the non-switching angle interval of forward and reverse stitching of thin material both correspond to the sinking of the feeding tooth below the needle plate, a cloth thickness threshold is set, when the thickness of the cloth being sewn does not exceed the cloth thickness threshold, the forward and reverse stitching switching operation is performed based on the thin material mode; when the thickness of the cloth being sewn exceeds the cloth thickness threshold, the forward and reverse stitching switching operation is performed based on the thick material mode.

[0010] Preferably, the ending angle of the non-switching angle interval of forward and reverse stitching of thick material and the ending angle of the non-switching angle interval of forward and reverse stitching of thin material are the same.

[0011] Preferably, the thin material positive and reverse stitch non-switching angle interval of the thin material mode, the thick material positive and reverse stitch non-switching angle interval of the thick material mode and the cloth thickness threshold value are stored in the control module, when the thickness of the sewing cloth does not exceed the cloth thickness threshold value, the control module selects the thin material mode and controls the triggering of the positive and reverse stitch switching signal according to the thin material positive and reverse stitch non-switching angle interval; when the thickness of the sewing cloth exceeds the cloth thickness threshold value, the control module selects the thick material mode and controls the triggering of the positive and reverse stitch switching signal according to the thick material positive and reverse stitch non-switching angle interval.

[0012] Preferably, a detection sensor for detecting the thickness of the sewing cloth is arranged, the detection sensor is in communication connection with the control module, and the control module selects the thin material mode or the thick material mode to control the triggering of the positive and reverse stitch switching signal according to the thickness of the sewing cloth detected by the detection sensor.

[0013] Preferably, the detection sensor is a displacement sensor, and the displacement sensor is arranged on the presser foot.

[0014] Compared with the prior art, the present application has significant progress:

[0015] The sewing machine needle breakage prevention control method of the present application selects a thin material mode or a thick material mode according to different sewing material thicknesses to perform forward and reverse sewing switching operations, thereby adjusting the angle at which the forward and reverse sewing switching signal is triggered to prevent needle breakage caused by forward and reverse sewing switching. When sewing thick material, the thick material mode is selected. Although the needle pierces the material at a higher position, the height of the needle from the upper surface of the needle plate corresponding to the starting angle of the thick material forward and reverse sewing non-switching angle interval increases with the increase in the thickness of the material. Therefore, when the forward and reverse sewing switching instruction is received, the spindle angle is already in the thick material forward and reverse sewing non-switching angle interval and cannot trigger the forward and reverse sewing switching signal, so the forward and reverse sewing switching is not immediately performed. Instead, the forward and reverse sewing switching signal is triggered to perform forward and reverse sewing switching only after the spindle angle reaches the end angle of the thick material forward and reverse sewing non-switching angle interval and the feed dog sinks below the needle plate, thereby avoiding needle breakage caused by forward and reverse sewing switching when sewing thick material. When sewing thin material, the thin material mode is selected. Since the height of the needle from the upper surface of the needle plate corresponding to the starting angle of the thin material forward and reverse sewing non-switching angle interval is low, when the forward and reverse sewing switching instruction is received at a low position from the needle plate, the spindle angle is already in the thin material forward and reverse sewing non-switching angle interval and cannot trigger the forward and reverse sewing switching signal, so the forward and reverse sewing switching is not immediately performed. Instead, the forward and reverse sewing switching signal is triggered to perform forward and reverse sewing switching only after the spindle angle reaches the end angle of the thin material forward and reverse sewing non-switching angle interval and the feed dog sinks below the needle plate, thereby avoiding the situation that when sewing thin material, the needle cannot trigger the forward and reverse sewing switching signal when it is at a high position from the thin material, and a needle is sewn more than once before reverse sewing. Needle breakage caused by forward and reverse sewing switching when sewing thin material is also avoided, and the response of forward and reverse sewing switching is ensured to be fast. The adaptability to different thicknesses of material is thus widened. Without changing the overall structure of the machine, only the control program needs to be changed to adapt to sewing different types of material. BRIEF DESCRIPTION OF DRAWINGS

[0016] FIG. 1 is a schematic diagram of the movement state of the feed dog during forward and reverse sewing switching in the prior art, in which FIG. 1-1 is forward sewing and FIG. 1-2 is reverse sewing.

[0017] FIG. 2 is a schematic diagram of the synchronization relationship between the needle and the feed dog in the prior art.

[0018] FIG. 3 is a schematic diagram of the needle piercing the material but the feed dog being above the needle plate in the prior art.

[0019] FIG. 4 is a schematic diagram of the forward and reverse sewing non-switching angle interval in the prior art.

[0020] FIG. 5 is a schematic diagram of the forward and reverse sewing non-switching angle interval in the sewing machine needle breakage prevention control method of an embodiment of the present application.

[0021] FIG. 6 is a control logic diagram of the sewing machine needle breakage prevention control method of an embodiment of the present application.

[0022] Wherein, the reference signs are explained as follows: 1 feeding tooth 2 needle plate 3 needle 4 cloth DETAILED DESCRIPTION

[0023] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings. These embodiments are only used to illustrate the present application, but not to limit the present application.

[0024] In the description of the present application, it should be noted that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0025] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0026] In addition, in the description of the present application, unless otherwise specified, the meaning of "multiple" is two or more.

[0027] As shown in FIGS. 5 and 6, an embodiment of the control method for preventing needle breakage of the sewing machine provided by the present application is provided.

[0028] Referring to FIG. 5, the control method of the sewing machine for preventing needle breakage in the embodiment sets a thin material mode and a thick material mode, the thin material mode has a thin material forward and reverse sewing non-switching angle interval, and the thick material mode has a thick material forward and reverse sewing non-switching angle interval. When the spindle angle is in the thin material forward and reverse sewing non-switching angle interval / thick material forward and reverse sewing non-switching angle interval, the forward and reverse sewing switching signal cannot be triggered. The starting angle of the thick material forward and reverse sewing non-switching angle interval corresponds to a height of the needle from the upper surface of the needle plate that is greater than the height of the needle from the upper surface of the needle plate corresponding to the starting angle of the thin material forward and reverse sewing non-switching angle interval. The ending angle of the thick material forward and reverse sewing non-switching angle interval and the ending angle of the thin material forward and reverse sewing non-switching angle interval both correspond to the feeding tooth sinking below the needle plate. Preferably, the ending angle of the thick material forward and reverse sewing non-switching angle interval and the ending angle of the thin material forward and reverse sewing non-switching angle interval are the same. That is, the thick material forward and reverse sewing non-switching angle interval is greater than the thin material forward and reverse sewing non-switching angle interval. When the spindle angle is at the starting angle of the thin material forward and reverse sewing non-switching angle interval / thick material forward and reverse sewing non-switching angle interval, the needle has a certain height from the upper surface of the needle plate, and the height of the needle from the upper surface of the needle plate corresponding to the starting angle of the thick material forward and reverse sewing non-switching angle interval is higher than the height of the needle from the upper surface of the needle plate corresponding to the starting angle of the thin material forward and reverse sewing non-switching angle interval. When the spindle angle reaches the ending angle of the thin material forward and reverse sewing non-switching angle interval / thick material forward and reverse sewing non-switching angle interval, the feeding tooth sinks below the needle plate. At this time, the forward and reverse sewing switching signal is triggered to switch the forward and reverse sewing, and the movement of the feeding tooth does not cause the needle that has penetrated into the fabric to be pulled off.

[0029] The control method of the sewing machine for preventing needle breakage in the embodiment also sets a fabric thickness threshold. When the thickness of the fabric being sewn does not exceed the fabric thickness threshold, the forward and reverse sewing switching operation is performed based on the thin material mode, that is, the forward and reverse sewing switching signal is not triggered in the thin material forward and reverse sewing non-switching angle interval. When the thickness of the fabric being sewn exceeds the fabric thickness threshold, the forward and reverse sewing switching operation is performed based on the thick material mode, that is, the forward and reverse sewing switching signal is not triggered in the thick material forward and reverse sewing non-switching angle interval.

[0030] Therefore, the needle breaking prevention control method of the sewing machine can select the thin material mode or the thick material mode according to different sewing material thicknesses to perform the forward and reverse sewing switching operation, so as to adjust the angle of the forward and reverse sewing switching signal trigger and prevent the needle breaking caused by the forward and reverse sewing switching. When sewing the thick material whose thickness exceeds the cloth thickness threshold value, the thick material mode is selected. Although the needle pierces into the cloth at a higher position, since the starting angle of the forward and reverse sewing non-switching angle interval corresponding to the height of the needle from the upper surface of the needle plate increases correspondingly with the increase of the cloth thickness, when the forward and reverse sewing switching instruction is received, the spindle angle is located in the forward and reverse sewing non-switching angle interval of the thick material, so the forward and reverse sewing switching signal cannot be triggered, the forward and reverse sewing switching is not immediately performed, and the forward and reverse sewing switching signal is triggered to perform the forward and reverse sewing switching only when the spindle angle reaches the ending angle of the forward and reverse sewing non-switching angle interval of the thick material and the feed dog sinks below the needle plate. Therefore, the needle breaking caused by the forward and reverse sewing switching during the sewing of the thick material can be avoided. When sewing the thin material whose thickness does not exceed the cloth thickness threshold value, the thin material mode is selected. Since the starting angle of the forward and reverse sewing non-switching angle interval corresponding to the height of the needle from the upper surface of the needle plate is low, when the forward and reverse sewing switching instruction is received, the forward and reverse sewing switching signal cannot be triggered because the spindle angle is located in the forward and reverse sewing non-switching angle interval of the thin material, the forward and reverse sewing switching is not immediately performed, and the forward and reverse sewing switching signal is triggered to perform the forward and reverse sewing switching only when the spindle angle reaches the ending angle of the forward and reverse sewing non-switching angle interval of the thin material and the feed dog sinks below the needle plate. Therefore, the situation that the sewing of the thin material causes the forward and reverse sewing switching to occur after the needle is sewn for one more time because the forward and reverse sewing switching signal cannot be triggered when the needle is at a higher position from the thin material can be avoided, the needle breaking caused by the forward and reverse sewing switching during the sewing of the thin material can be avoided, and the response of the forward and reverse sewing switching can be ensured. Therefore, the adaptability to different thicknesses of cloth is widened, and the sewing of different types of cloth can be adapted by only changing the control program without changing the structure of the whole machine.

[0031] The control method of the sewing machine needle breakage prevention of the embodiment stores the thin material forward and reverse sewing non-switching angle interval of the thin material mode, the thick material forward and reverse sewing non-switching angle interval of the thick material mode and the cloth thickness threshold value in the control module, and the control module is the existing electric control structure of the existing sewing machine. When the thickness of the cloth being sewn does not exceed the cloth thickness threshold value, the control module selects the thin material mode and controls the triggering of the forward and reverse sewing switching signal according to the thin material forward and reverse sewing non-switching angle interval, that is, when the control module receives the forward and reverse sewing switching instruction: if the spindle angle is not in the thin material forward and reverse sewing non-switching angle interval, the control module triggers the forward and reverse sewing switching signal; if the spindle angle is in the thin material forward and reverse sewing non-switching angle interval, the control module does not trigger the forward and reverse sewing switching signal, and after the spindle angle reaches the terminal angle of the thin material forward and reverse sewing non-switching angle interval, the control module triggers the forward and reverse sewing switching signal again. When the thickness of the cloth being sewn exceeds the cloth thickness threshold value, the control module selects the thick material mode and controls the triggering of the forward and reverse sewing switching signal according to the thick material forward and reverse sewing non-switching angle interval, that is, when the control module receives the forward and reverse sewing switching instruction: if the spindle angle is not in the thick material forward and reverse sewing non-switching angle interval, the control module triggers the forward and reverse sewing switching signal; if the spindle angle is in the thick material forward and reverse sewing non-switching angle interval, the control module does not trigger the forward and reverse sewing switching signal, and after the spindle angle reaches the terminal angle of the thick material forward and reverse sewing non-switching angle interval, the control module triggers the forward and reverse sewing switching signal again.

[0032] In the embodiment, preferably, a detection sensor for detecting the thickness of the cloth being sewn is arranged, the detection sensor is in communication connection with the control module, the detection sensor sends the detected cloth thickness information to the control module, and the control module receives the information to obtain the cloth thickness. The control module selects the thin material mode or the thick material mode according to the cloth thickness detected by the detection sensor to control the triggering of the forward and reverse sewing switching signal. In this way, by arranging the detection sensor to identify the cloth thickness, the corresponding thin material mode or thick material mode can be adaptively selected to control the response of the forward and reverse sewing switching during the sewing process, so that the intelligent level of the sewing machine is further improved. Preferably, the detection sensor is a displacement sensor, which can be arranged on the presser foot to automatically sense the thickness of the cloth.

[0033] In summary, referring to FIG. 6, the control logic of the control method of the sewing machine needle breakage prevention of the embodiment includes the following steps.

[0034] Step S1, setting the sewing parameters, storing the sewing parameters in the control module, the sewing parameters including the thin material forward and reverse sewing non-switching angle interval of the thin material mode, the thick material forward and reverse sewing non-switching angle interval of the thick material mode and the cloth thickness threshold value.

[0035] Step S2, confirming mode: the cloth thickness is detected by the detection sensor and sent to the control module, the control module judges whether the cloth thickness is within the cloth thickness threshold: if yes, steps S3-S4 are executed; if no, steps S5-S6 are executed.

[0036] Step S3, selecting thin material mode.

[0037] Step S4, obtaining the non-switching angle interval of the forward and reverse sewing of the thin material as the non-switching angle interval.

[0038] Step S5, selecting thick material mode.

[0039] Step S6, obtaining the non-switching angle interval of the forward and reverse sewing of the thick material as the non-switching angle interval.

[0040] Step S7, whether the control module receives the forward and reverse sewing switching instruction: if yes, step S8 is executed; if no, step S11 is executed.

[0041] Step S8, the control module judges whether the spindle angle is within the non-switching angle interval: if yes, step S9 is executed; if no, step S10 is executed.

[0042] Step S9, the spindle rotates to the end angle of the non-switching angle interval.

[0043] Step S10, the control module triggers the forward and reverse sewing switching signal to switch the forward and reverse sewing.

[0044] Step S11, continue sewing.

[0045] The above is only the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the technical principles of the present application, can make several improvements and replacements, these improvements and replacements should also be considered as the protection scope of the present application.

Claims

1. A control method for preventing needle breakage in a sewing machine, characterized in that, A thin-material mode with a non-switching angle range for forward and reverse sewing of thin materials and a thick-material mode with a non-switching angle range for forward and reverse sewing of thick materials are defined. The height of the needle from the upper surface of the needle plate corresponding to the starting angle of the non-switching angle range for forward and reverse sewing of thick materials is greater than the height of the needle from the upper surface of the needle plate corresponding to the starting angle of the non-switching angle range for forward and reverse sewing of thin materials. The ending angles of both the non-switching angle ranges for forward and reverse sewing of thick materials and thin materials correspond to the feed dog sinking below the needle plate. A fabric thickness threshold is set. When the fabric thickness being sewn does not exceed the fabric thickness threshold, a forward and reverse sewing switching operation is performed based on the thin-material mode; when the fabric thickness being sewn exceeds the fabric thickness threshold, a forward and reverse sewing switching operation is performed based on the thick-material mode.

2. The sewing machine needle breakage prevention control method according to claim 1, characterized in that, The termination angle of the non-switching angle range for the thick material forward and backward seams is the same as the termination angle of the non-switching angle range for the thin material forward and backward seams.

3. The sewing machine needle breakage prevention control method according to claim 1, characterized in that, The control module stores the non-switching angle range for thin fabric forward and backward stitching in the thin fabric mode, the non-switching angle range for thick fabric forward and backward stitching in the thick fabric mode, and the fabric thickness threshold. When the fabric thickness being sewn does not exceed the fabric thickness threshold, the control module selects the thin fabric mode and controls the triggering of the forward and backward stitching switching signal according to the non-switching angle range for thin fabric forward and backward stitching; when the fabric thickness being sewn exceeds the fabric thickness threshold, the control module selects the thick fabric mode and controls the triggering of the forward and backward stitching switching signal according to the non-switching angle range for thick fabric forward and backward stitching.

4. The sewing machine needle breakage prevention control method according to claim 3, characterized in that, A detection sensor is provided to detect the thickness of the fabric being sewn. The detection sensor is communicatively connected to the control module. The control module selects either the thin fabric mode or the thick fabric mode based on the fabric thickness detected by the detection sensor to control the triggering of the forward and reverse sewing switching signal.

5. The sewing machine needle breakage prevention control method according to claim 4, characterized in that, The detection sensor is a displacement sensor, which is mounted on the pressure foot.

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