Control method for preventing needle breakage of sewing machine

Abstract

The invention relates to the technical field of sewing machines, in particular to a control method for preventing needle breakage of a sewing machine, which comprises the following steps of: setting a thin material mode with a thin material forward and backstitch non-switching angle interval and a thick material mode with a thick material forward and backstitch non-switching angle interval; the height from the machine needle corresponding to the starting angle of the thick material forward and backstitch non-switching angle interval to the upper surface of the needle plate is greater than the height from the machine needle corresponding to the starting angle of the thin material forward and backstitch non-switching angle interval to the upper surface of the needle plate; the termination angle of the thick-material forward and backstitch non-switching angle interval and the termination angle of the thin-material forward and backstitch non-switching angle interval correspond to the situation that feeding teeth sink below a needle plate, a cloth thickness threshold value is set, and when the thickness of sewn cloth does not exceed the cloth thickness threshold value, forward and backstitch switching operation is carried out based on a thin-material mode; and when the thickness of the sewn cloth exceeds a cloth thickness threshold value, forward and reverse sewing switching operation is carried out based on the thick material mode. Needle breakage is prevented when thick materials are sewed, multi-stitch one-needle sewing is avoided when thin materials are sewed, and forward and reverse stitch switching response is fast.

Description

Technical Field

[0001] The invention relates to the technical field of sewing machines, and in particular to a control method for preventing needle breakage of a sewing machine. Background Art

[0002] The sewing machine will have multiple forward and reverse stitching processes for local reinforcement during the sewing process. When the sewing machine performs forward and reverse stitching to reinforce thick materials, the instantaneous movement of the feed dog when switching between forward and reverse stitching may cause the needle to break, affecting the sewing effect.

[0003] See also Figure 1 In the standard sewing mode of the prior art, the motion trajectory of the feed dog 1 is an elliptical shape. When receiving the forward and reverse sewing switching instruction, the feed dog 1 will move instantly. Figure 1-1 As shown in 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 certain 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 switch direction to reverse sewing.

[0004] See also Figure 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 height of the upper surface of the needle plate 2, the feed dog 1 also moves from top to bottom to the height of the upper surface of the needle plate 2. Therefore, in a sewing cycle, the needle 3 may penetrate the fabric 4 but the feed dog 1 may be above the needle plate 2, such as Figure 3 As shown. If the forward and reverse stitch switching signal is triggered at this time, the feed dog 1 will move with the fabric 4 and pull off the needle 3 that has penetrated the fabric 4. Therefore, in the sewing control program, the forward and reverse stitch switching signal cannot be triggered for a short period of time before the needle 3 penetrates the needle plate 2 to prevent the needle from breaking when switching between forward and reverse stitches. The spindle angle range corresponding to this short period of time when the forward and reverse stitch switching signal cannot be triggered is the forward and reverse stitch non-switching angle interval. When the spindle is at the starting angle of the forward and reverse stitch non-switching angle interval, the needle 3 has a certain height from the upper surface of the needle plate 2; as the spindle rotates within the forward and reverse stitch non-switching angle interval, the height of the needle 3 from the upper surface of the needle plate 2 gradually decreases, and the feed dog 1 moves synchronously from top to bottom during this process; when the spindle rotates to the end angle of the forward and reverse stitch non-switching angle interval, the feed dog 1 sinks below the needle plate 2. When receiving the forward and reverse sewing switching instruction, if the spindle angle is in the forward and reverse sewing non-switching angle range, the forward and reverse sewing switching signal will not be triggered. After the spindle rotates to the end angle of the forward and reverse sewing non-switching angle range, the forward and reverse sewing switching signal will be triggered to switch to the forward and reverse sewing. At this time, the feed dog 1 has sunk below the needle plate 2, and the feed dog 1 will not move with the fabric 4 and pull off the needle 3 that has pierced the fabric 4.

[0005] See also Figure 4, the forward and reverse stitching non-switching angle range set in the prior art is about 20°-90°, corresponding to the maximum height of the needle 3 from the upper surface of the needle plate 2 of about 6 mm, which is a fixed value and does not change due to changes in the fabric 4. Therefore, when the thickness of the fabric 4 is greater than the fixed value, the needle 3 will penetrate the fabric 4 before the spindle angle enters the forward and reverse stitching non-switching angle range. In the case where the forward and reverse stitching switching signal is triggered before the spindle angle enters the forward and reverse stitching non-switching angle range, the feed dog 1 will still move with the fabric 4 and pull the needle 3 that has penetrated the fabric 4 apart.

[0006] If the set forward and reverse sewing non-switching angle range is increased, the starting angle of the forward and reverse sewing non-switching angle range is made smaller, so as to increase the corresponding maximum height of the needle 3 from the upper surface of the needle plate 2, and obtain a larger forward and reverse sewing non-switching angle range corresponding to the maximum height m of the needle 3 from the upper surface of the needle plate 2, then when the needle 3 moves from top to bottom to the height m, the forward and reverse sewing switching signal cannot be triggered. Although this can reduce needle breakage caused by forward and reverse sewing switching, when sewing thin materials with thin thickness, the forward and reverse sewing switching signal cannot be triggered when the needle 3 is at a position higher than the thin material, and reverse sewing will be performed after one more stitch. At the same time, the response of the forward and reverse sewing switching is also reduced, affecting the customer's sewing experience. Summary of the invention

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

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions:

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

[0010] Preferably, the end angle of the non-switching angle interval for forward and reverse sewing of thick materials is the same as the end angle of the non-switching angle interval for forward and reverse sewing of thin materials.

[0011] Preferably, the control module stores the thin material mode's thin material forward and reverse sewing non-switching angle interval, the thick material mode's thick material forward and reverse sewing non-switching angle interval, and the fabric thickness threshold. When the thickness of the sewn fabric does not exceed the fabric thickness threshold, 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; when the sewn fabric thickness exceeds the fabric thickness threshold, 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.

[0012] Preferably, a detection sensor is provided for detecting the thickness of the fabric being sewn, and the detection sensor is communicatively connected with the control module. The control module selects the thin material mode or the thick material mode according to the fabric thickness detected by the detection sensor to control the triggering of the forward and reverse sewing switching signal.

[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 invention has significant improvements:

[0015] The control method for preventing the sewing machine from breaking needles of the present invention selects the thin material mode or the thick material mode to perform the forward and reverse stitching switching operation according to different thicknesses of the sewing fabrics, thereby adjusting the angle at which the forward and reverse stitching switching signal is triggered to prevent the forward and reverse stitching switching from causing the machine needle to break. When the thick material mode is selected for sewing thick materials, although the machine needle penetrates the fabric at a higher position, the height of the machine needle from the upper surface of the needle plate corresponding to the starting angle of the forward and reverse stitching non-switching angle interval for thick materials increases corresponding to the increase in fabric thickness. Therefore, when the forward and reverse stitching switching instruction is received, the spindle angle is already in the forward and reverse stitching non-switching angle interval for thick materials and the forward and reverse stitching switching signal cannot be triggered. The forward and reverse stitching switching will not be performed immediately, but the forward and reverse stitching switching signal will be triggered to perform the forward and reverse stitching switching after the spindle angle reaches the end angle of the forward and reverse stitching non-switching angle interval for thick materials and the feed dog sinks below the needle plate. Therefore, the needle breakage caused by the forward and reverse stitching switching when sewing thick materials can be avoided. When sewing thin materials, select the thin material mode. Since the starting angle of the non-switching angle interval for forward and reverse stitching of thin materials corresponds to a lower height of the needle from the upper surface of the needle plate, when the needle receives the forward and reverse stitch switching command at a lower position from the needle plate, the spindle angle is located in the non-switching angle interval for forward and reverse stitching of thin materials and the forward and reverse stitch switching signal cannot be triggered. The forward and reverse stitch switching will not be performed immediately, but the spindle angle will reach the end angle of the non-switching angle interval for forward and reverse stitching of thin materials and the feed dog will sink below the needle plate before the forward and reverse stitch switching signal is triggered to perform the forward and reverse stitch switching. This can avoid the situation where reverse stitching is performed after sewing one more stitch because the needle cannot trigger the forward and reverse stitch switching signal when it is at a higher position from the thin material. It can also avoid the broken needle caused by the forward and reverse stitch switching when sewing thin materials, and ensure the fast response of the forward and reverse stitch switching. This broadens the adaptability to fabrics of different thicknesses. Without changing the structure of the entire machine, it can adapt to the sewing of different types of fabrics by only changing the control program. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the motion state of the feed dog when switching between forward and reverse stitching in the prior art, wherein Figure 1-1 For the positive seam, Figure 1-2 For reverse stitching.

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

[0018] Figure 3 It is a schematic diagram of the prior art in which the needle penetrates the fabric but the feed dog is located above the needle plate.

[0019] Figure 4 It is a schematic diagram of the angle range in which the forward and reverse stitching does not switch in the prior art.

[0020] Figure 5 It is a schematic diagram of the non-switching angle interval of forward and reverse sewing in the control method for preventing needle breakage of a sewing machine according to an embodiment of the present invention.

[0021] Figure 6 It is a control logic diagram of a control method for preventing needle breakage of a sewing machine according to an embodiment of the present invention.

[0022] The reference numerals are described as follows:

[0023] 1 feed dog

[0024] 2 Needle plate

[0025] 3 Needle

[0026] 4. Fabric DETAILED DESCRIPTION

[0027] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. These embodiments are only used to illustrate the present invention, but not to limit the present invention.

[0028] In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are 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 cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0029] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0031] like Figure 5 and Figure 6 The figure shows an embodiment of the control method for preventing needle breakage of a sewing machine provided by the present invention.

[0032] See also Figure 5, the control method for preventing the sewing machine from breaking needles in this embodiment sets a thin material mode and a thick material mode. The thin material mode has an angle interval in which forward and reverse sewing of thin materials is not switched, and the thick material mode has an angle interval in which forward and reverse sewing of thick materials is not switched. When the spindle angle is within the angle interval in which forward and reverse sewing of thin materials is not switched / the angle interval in which forward and reverse sewing of thick materials is not switched, the forward and reverse sewing switching signal cannot be triggered. The height of the needle from the upper surface of the needle plate corresponding to the starting angle of the angle interval in which forward and reverse sewing of thick materials is not switched is greater than the height of the needle from the upper surface of the needle plate corresponding to the starting angle of the angle interval in which forward and reverse sewing of thin materials is not switched. The end angle of the angle interval in which forward and reverse sewing of thick materials is not switched and the end angle of the angle interval in which forward and reverse sewing of thin materials is not switched both correspond to the feed dog sinking below the needle plate. Preferably, the end angle of the angle interval in which forward and reverse sewing of thick materials is not switched is the same as the end angle of the angle interval in which forward and reverse sewing of thin materials is not switched. That is, the angle interval in which forward and reverse sewing of thick materials is not switched is greater than the angle interval in which forward and reverse sewing of thin materials is not switched. When the spindle angle is at the starting angle of the non-switching angle range for forward and reverse stitching of thin materials / the non-switching angle range for forward and reverse stitching of thick materials, the needle is at 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 non-switching angle range for forward and reverse stitching of thick materials is higher 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 stitching of thin materials. When the spindle angle reaches the ending angle of the non-switching angle range for forward and reverse stitching of thin materials / the non-switching angle range for forward and reverse stitching of thick materials, the feed dog sinks below the needle plate, and at this time, the forward and reverse stitching switching signal is triggered to switch to forward and reverse stitching, and the movement of the feed dog will not move the fabric and cause the needle that has been inserted into the fabric to be pulled off.

[0033] The control method for preventing needle breakage of a sewing machine in the present embodiment also sets a fabric thickness threshold. When the thickness of the sewing fabric 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 within the angle range where forward and reverse sewing of thin materials is not switched; when the thickness of the sewing fabric 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 within the angle range where forward and reverse sewing of thick materials is not switched.

[0034] Therefore, the control method for preventing the sewing machine from breaking needles in this embodiment can select the thin material mode or the thick material mode to perform the forward and reverse stitching switching operation according to different sewing fabric thicknesses, thereby adjusting the angle at which the forward and reverse stitching switching signal is triggered to prevent the forward and reverse stitching switching from causing the machine needle to break. When the sewing thickness exceeds the threshold value of the fabric thickness, the thick material mode is selected. Although the machine needle penetrates the fabric at a higher position, the height of the machine needle from the upper surface of the needle plate corresponding to the starting angle of the forward and reverse stitching non-switching angle interval of the thick material increases corresponding to the increase in fabric thickness. Therefore, when the forward and reverse stitching switching instruction is received, the spindle angle is already in the forward and reverse stitching non-switching angle interval of the thick material and the forward and reverse stitching switching signal cannot be triggered. The forward and reverse stitching switching will not be performed immediately, but the forward and reverse stitching switching signal will be triggered to perform the forward and reverse stitching switching after the spindle angle reaches the end angle of the forward and reverse stitching non-switching angle interval of the thick material and the feed dog sinks below the needle plate. Therefore, the needle breakage caused by the forward and reverse stitching switching during the sewing of thick materials can be avoided. When sewing thin materials whose thickness does not exceed the threshold of fabric thickness, the thin material mode is selected. Since the starting angle of the non-switching angle interval for forward and reverse sewing of thin materials corresponds to a lower height of the needle from the upper surface of the needle plate, when the needle receives the forward and reverse sewing switching instruction at a lower position from the needle plate, the forward and reverse sewing switching signal cannot be triggered because the spindle angle is within the non-switching angle interval for forward and reverse sewing of thin materials. The forward and reverse sewing switching will not be performed immediately, but the forward and reverse sewing switching signal will be triggered only after the spindle angle reaches the end angle of the non-switching angle interval for forward and reverse sewing of thin materials and the feed dog sinks below the needle plate. This can avoid the situation where reverse sewing is performed after sewing one more stitch because the needle cannot trigger the forward and reverse sewing switching signal when it is at a higher position from the thin material. It can also avoid the broken needle caused by the forward and reverse sewing switching when sewing thin materials, and ensure the fast response of the forward and reverse sewing switching. This broadens the adaptability to fabrics of different thicknesses. Without changing the structure of the whole machine, it can adapt to the sewing of different types of fabrics by only changing the control program.

[0035] In the control method for preventing needle breakage of a sewing machine of the present embodiment, the control module stores the non-switching angle interval of the thin material forward and reverse sewing of the thin material mode, the non-switching angle interval of the thick material forward and reverse sewing of the thick material mode, and the threshold value of the thickness of the fabric, and the control module is the existing electric control structure of the existing sewing machine. When the thickness of the sewn fabric does not exceed the threshold value of the thickness of the fabric, the control module selects the thin material mode and controls the triggering of the forward and reverse sewing switching signal according to the non-switching angle interval of the thin material forward and reverse sewing, that is, when the control module receives the forward and reverse sewing switching instruction: if the spindle angle is not within the non-switching angle interval of the thin material forward and reverse sewing, the control module triggers the forward and reverse sewing switching signal; if the spindle angle is within the non-switching angle interval of the thin material forward and reverse sewing, the control module does not trigger the forward and reverse sewing switching signal until the spindle angle reaches the end angle of the non-switching angle interval of the thin material forward and reverse sewing, and then the control module triggers the forward and reverse sewing switching signal. When the thickness of the sewn fabric exceeds the fabric thickness threshold, the control module selects the thick material mode and controls the triggering of the forward and reverse sewing switching signal according to the angle range for thick material forward and reverse sewing without switching, that is, when the control module receives the forward and reverse sewing switching instruction: if the spindle angle is not within the angle range for thick material forward and reverse sewing without switching, the control module triggers the forward and reverse sewing switching signal; if the spindle angle is within the angle range for thick material forward and reverse sewing without switching, the control module does not trigger the forward and reverse sewing switching signal until the spindle angle reaches the end angle of the angle range for thick material forward and reverse sewing without switching, and then the control module triggers the forward and reverse sewing switching signal again.

[0036] In this embodiment, preferably, a detection sensor is provided for detecting the thickness of the fabric to be sewn. The detection sensor is communicatively connected with the control module. The detection sensor transmits the detected fabric thickness information to the control module. The control module receives the information to obtain the fabric thickness. The control module selects the thin material mode or the thick material mode to control the triggering of the forward and reverse stitching switching signal according to the fabric thickness detected by the detection sensor. Therefore, by setting up a detection sensor to identify the fabric thickness, it is possible to realize adaptive adjustment corresponding to fabrics of different thicknesses during the sewing process to select the corresponding thin material mode or thick material mode to control the response of the forward and reverse stitching switching, so that the intelligence level of the sewing machine is further improved. Preferably, the detection sensor is a displacement sensor, which can be set on the presser foot to realize automatic sensing of the thickness of the fabric.

[0037] In summary, see Figure 6 The control logic of the sewing machine needle breakage prevention control method of this embodiment includes the following steps.

[0038] Step S1, setting sewing parameters, storing the sewing parameters in the control module, the sewing parameters including the non-switching angle interval of thin material forward and reverse sewing in the thin material mode, the non-switching angle interval of thick material forward and reverse sewing in the thick material mode, and the fabric thickness threshold.

[0039] Step S2, confirmation mode: the fabric thickness is detected by the detection sensor and transmitted to the control module, and the control module determines whether the fabric thickness is within the fabric thickness threshold: if so, execute steps S3-S4; if not, execute steps S5-S6.

[0040] Step S3, selecting the thin material mode.

[0041] Step S4, obtaining the non-switching angle interval for forward and reverse sewing of thin materials as the non-switching angle interval.

[0042] Step S5, selecting thick material mode.

[0043] Step S6, obtaining the non-switching angle interval for forward and reverse sewing of thick materials as the non-switching angle interval.

[0044] Step S7, whether the control module receives the forward and reverse sewing switching instruction: if so, execute step S8; if not, execute step S11.

[0045] Step S8, the control module determines whether the spindle angle is within the non-switching angle range: if so, execute step S9; if not, execute step S10.

[0046] Step S9: The main shaft rotates until the main shaft angle reaches the end angle of the non-switching angle range.

[0047] Step S10: The control module triggers a forward-reverse sewing switching signal to switch between forward and reverse sewing.

[0048] Step S11, continue sewing.

[0049] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

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 interval for forward and reverse sewing of thin materials and a thick material mode with a non-switching angle interval for forward and reverse sewing of thick materials are set, the height of the needle from the upper surface of the needle plate corresponding to the starting angle of the non-switching angle interval 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 interval for forward and reverse sewing of thin materials, the ending angle of the non-switching angle interval for forward and reverse sewing of thick materials and the ending angle of the non-switching angle interval for forward and reverse sewing of thin materials both correspond to the feed dog sinking below the needle plate, a fabric thickness threshold is set, when the thickness of the sewn fabric does not exceed the fabric thickness threshold, the forward and reverse sewing switching operation is performed based on the thin material mode; when the thickness of the sewn fabric exceeds the fabric thickness threshold, the forward and reverse sewing switching operation is performed based on the thick material mode.

2. The control method for preventing needle breakage of a sewing machine according to claim 1, characterized in that: The end angle of the non-switching angle interval for forward and reverse sewing of thick materials is the same as the end angle of the non-switching angle interval for forward and reverse sewing of thin materials.

3. The control method for preventing needle breakage of a sewing machine according to claim 1, characterized in that: The control module stores the thin material mode's angle interval for non-switching forward and reverse sewing, the thick material mode's angle interval for non-switching forward and reverse sewing, and the fabric thickness threshold. When the thickness of the sewn fabric does not exceed the fabric thickness threshold, 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; when the thickness of the sewn fabric exceeds the fabric thickness threshold, 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.

4. The control method for preventing needle breakage of a sewing machine according to claim 3, characterized in that: A detection sensor is provided for detecting the thickness of the fabric to be sewn. The detection sensor is in communication connection with the control module. The control module selects the thin material mode or the thick material mode to control the triggering of the forward and reverse sewing switching signal according to the fabric thickness detected by the detection sensor.

5. The control method for preventing needle breakage of a sewing machine according to claim 4, characterized in that: The detection sensor is a displacement sensor, and the displacement sensor is arranged on the presser foot.

Images