阅读说明：本技术 一种感应器切换控制方法 (Inductor switching control method ) 是由 符志诚 朱良华 徐永明 于 2019-03-13 设计创作，主要内容包括：本发明提供一种感应器切换控制方法,包括以下步骤：设置都用于检测缝料前边缘的第二感应器和第三感应器；电控模块中预设有参数阈值；缝纫机缝纫时,电控模块获取缝纫机的运行状态参数,运行状态参数用于表征缝纫机运行时的针距大小或缝纫速度的大小；当电控模块判断运行状态参数小于参数阈值时,电控模块根据第三感应器的反馈信号控制前剪线下刀时间T；当电控模块判断运行状态参数大于等于参数阈值时,电控模块根据第二感应器的反馈信号控制前剪线下刀时间T。本申请在缝纫机低速、小针距缝纫的情况下选择第三感应器控制前剪线,在缝纫机高速、大针距缝纫的情况下选择第二感应器控制前剪线,在实现短线头的剪线效果时有效避免砍布现象。(The invention provides a sensor switching control method, which comprises the following steps: arranging a second sensor and a third sensor which are used for detecting the front edge of the sewing material; a parameter threshold value is preset in the electric control module; when the sewing machine sews, the electric control module obtains the operation state parameter of the sewing machine, and the operation state parameter is used for representing the needle pitch or the sewing speed when the sewing machine operates; when the electric control module judges that the running state parameter is smaller than the parameter threshold value, the electric control module controls the front trimming cutting time T according to the feedback signal of the third sensor; and when the electric control module judges that the running state parameter is more than or equal to the parameter threshold value, the electric control module controls the front trimming cutting time T according to the feedback signal of the second sensor. This application selects the preceding trimming of third inductor control under the condition of sewing machine low-speed, little gauge needle sewing, selects the preceding trimming of second inductor control under the condition of sewing machine high-speed, big gauge needle sewing, effectively avoids cutting cloth phenomenon when realizing the trimming effect of stub.)

1. A method for controlling sensor switching, comprising: the method comprises the following steps:

s1, arranging a second sensor and a third sensor which are used for detecting the front edge of the sewing material, wherein the second sensor and the third sensor are connected with an electric control module in the sewing machine, and the second sensor, the third sensor and a thread trimming cutter assembly in the sewing machine are sequentially arranged from back to front along the forward cloth feeding direction of the sewing machine;

s2, presetting a parameter threshold in an electric control module of the sewing machine;

s3, when the sewing machine sews, the electric control module obtains the running state parameters of the sewing machine, the running state parameters are used for representing the needle pitch size or the sewing speed size when the sewing machine runs, the electric control module compares the running state parameters with the parameter threshold value and controls the front trimming thread feeding time T according to the comparison result:

when the electric control module judges that the running state parameter is smaller than the parameter threshold value, the electric control module shields the feedback signal of the second sensor, and the electric control module controls the front trimming cutting time T according to the feedback signal of the third sensor;

when the electric control module judges that the running state parameter is larger than or equal to the parameter threshold value, the electric control module shields the feedback signal of the third sensor, and the electric control module controls the front trimming cutting time T according to the feedback signal of the second sensor.

2. The inductor switching control method according to claim 1, wherein: the operation state parameter is a needle pitch parameter U, and the parameter threshold is a needle pitch threshold X1; the stitch length parameter U is set by a user via an operation panel on the sewing machine before the sewing machine starts sewing.

3. The inductor switching control method according to claim 1, wherein: the operation state parameter is a needle pitch parameter U, and the parameter threshold is a needle pitch threshold X1; when the sewing machine sews, the stitch length parameter U is automatically obtained by the electric control module.

4. The inductor switching control method according to claim 3, wherein: the automatic acquisition mode of the needle pitch parameter U by the electronic control module is as follows: and the electronic control module automatically calculates a needle pitch parameter U according to the voltage value V of the second inductor and the rotating speed S of a main motor of the sewing machine when the front edge of the sewing material passes through the second inductor, wherein the U is f (V, S).

5. The inductor switching control method according to claim 1, wherein: the running state parameter is a motor rotating speed parameter W, and the parameter threshold is a sewing speed threshold X2; and the electric control module acquires the rotating speed S of the main motor of the sewing machine when the front edge of the sewing material passes through the second sensor and marks the rotating speed S of the main motor of the sewing machine as the motor rotating speed parameter W.

6. The inductor switching control method according to claim 1, wherein: the front trimming cutting time T is a set value prestored in the electric control module.

7. The inductor switching control method according to claim 1, wherein: the front trimming cutting time T is automatically calculated and obtained by an electric control module;

as an electric control module rootWhen the front trimming cutting time T is controlled according to the feedback signal of the second sensor, the calculation mode of the front trimming cutting time T is as follows: t ═ L1/(P × n1) -Tc₁Wherein L1 is the distance between the second sensor and the thread cutting edge of the thread cutting knife assembly, P is the current needle pitch of the sewing machine during sewing, n1 is the current rotating speed of the main motor of the sewing machine when the front edge of the sewing material passes through the second sensor, Tc₁Is the response time of the second inductor;

when the electric control module controls the front trimming cutting time T according to the feedback signal of the third sensor, the calculation mode of the front trimming cutting time T is as follows: t ═ L2/(P × n2) -Tc₂Wherein L2 is the distance from the third sensor to the thread cutting edge of the thread cutting knife assembly, P is the current needle pitch of the sewing machine during sewing, n2 is the current rotating speed of the main motor of the sewing machine when the front edge of the sewing material passes through the third sensor, Tc₂Is the response time of the third inductor.

8. The inductor switching control method according to claim 7, wherein: the electric control module is also prestored with a safe cutting time parameter Ta; when the front trimming cutting time T obtained by automatic calculation of the electronic control module is less than the safe cutting time parameter Ta, the electronic control module controls the trimming cutter assembly to execute the front trimming action according to the front trimming cutting time T; when the electric control module automatically calculates that the obtained front trimming line cutting time T is larger than or equal to the safe cutting time parameter Ta, the electric control module controls the trimming cutter assembly to execute the front trimming line action according to the safe cutting time parameter Ta.

Technical Field

The invention relates to the field of sewing machines, in particular to a sensor switching control method for thread cutting control of a sewing machine.

Background

At present, a plurality of sensors are arranged in a sewing machine, each sensor is connected with an electric control module of the sewing machine, the sensors are used for detecting the edges of sewing materials, and information about whether the sewing materials pass through the sensors or not can be acquired through feedback signals of the sensors so as to carry out a series of automatic control on the sewing machine. The view shown in fig. 1 is provided with four sensors, the four sensors are respectively a first sensor 1, a second sensor 2, a third sensor 3 and a fourth sensor 4, the first sensor 1, the second sensor 2, the third sensor 3 and the fourth sensor 4 are sequentially arranged from back to front along the forward moving direction of the sewing material when the sewing machine sews, so that the sewing material can sequentially pass through the forward moving direction of the sewing material when the sewing machine sews; wherein, the first inductor 1 is used for sewing and presser foot lifting control; the second inductor 2 and the third inductor 3 are used for front trimming control, and the fourth inductor 4 is used for rear trimming control. In addition, in the sewing machine shown in fig. 1, the first sensor 1 and the second sensor 2 are installed on the sewing table 5 of the sewing machine, the third sensor 3 is installed on the needle plate 6 of the sewing machine, and the fourth sensor 4 is installed on the thread trimmer assembly 7, so that the second sensor 2 and the third sensor 3 are both located at the rear side of the thread trimmer assembly 7, and the third sensor 3 is closer to the thread trimmer assembly 7 than the second sensor 2.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a sensor switching control method for automatically selecting a sensor for front trimming control according to an operating state parameter of a sewing machine, thereby preventing a cloth cutting phenomenon during front trimming.

In order to achieve the above object, the present invention provides a method for controlling sensor switching, comprising the following steps:

s1, arranging a second sensor and a third sensor which are used for detecting the front edge of the sewing material, wherein the second sensor and the third sensor are connected with an electric control module in the sewing machine, and the second sensor, the third sensor and a thread trimming cutter assembly in the sewing machine are sequentially arranged from back to front along the forward cloth feeding direction of the sewing machine;

s2, presetting a parameter threshold in an electric control module of the sewing machine;

s3, when the sewing machine sews, the electric control module obtains the running state parameters of the sewing machine, the running state parameters are used for representing the needle pitch size or the sewing speed size when the sewing machine runs, the electric control module compares the running state parameters with the parameter threshold value and controls the front trimming thread feeding time T according to the comparison result:

when the electric control module judges that the running state parameter is smaller than the parameter threshold value, the electric control module shields the feedback signal of the second sensor, and the electric control module controls the front trimming cutting time T according to the feedback signal of the third sensor;

when the electric control module judges that the running state parameter is larger than or equal to the parameter threshold value, the electric control module shields the feedback signal of the third sensor, and the electric control module controls the front trimming cutting time T according to the feedback signal of the second sensor.

Further, the operating state parameter is a needle pitch parameter U, and the parameter threshold is a needle pitch threshold X1; the stitch length parameter U is set by a user via an operation panel on the sewing machine before the sewing machine starts sewing.

Further, the operating state parameter is a needle pitch parameter U, and the parameter threshold is a needle pitch threshold X1; when the sewing machine sews, the stitch length parameter U is automatically obtained by the electric control module.

Further, the manner of automatically acquiring the needle pitch parameter U by the electronic control module is as follows: and the electronic control module automatically calculates a needle pitch parameter U according to the voltage value V of the second inductor and the rotating speed S of a main motor of the sewing machine when the front edge of the sewing material passes through the second inductor, wherein the U is f (V, S).

Further, the running state parameter is a motor rotating speed parameter W, and the parameter threshold is a sewing speed threshold X2; and the electric control module acquires the rotating speed S of the main motor of the sewing machine when the front edge of the sewing material passes through the second sensor and marks the rotating speed S of the main motor of the sewing machine as the motor rotating speed parameter W.

Further, the front trimming cutting time T is a set value prestored in the electric control module.

Further, the front trimming cutting time T is automatically calculated and obtained by an electric control module;

when the electric control module controls the front trimming cutting time T according to the feedback signal of the second sensor, the calculation mode of the front trimming cutting time T is as follows: t ═ L1/(P × n1) -Tc₁Wherein L1 is the distance between the second sensor and the thread cutting edge of the thread cutting knife assembly, P is the current needle pitch of the sewing machine during sewing, n1 is the current rotating speed of the main motor of the sewing machine when the front edge of the sewing material passes through the second sensor, Tc₁Is the response time of the second inductor;

when the electric control module controls the front trimming cutting time T according to the feedback signal of the third sensor, the calculation mode of the front trimming cutting time T is as follows: t ═ L2/(P × n2) -Tc₂Wherein L2 is the distance from the third sensor to the thread cutting edge of the thread cutting knife assembly, P is the current needle pitch of the sewing machine during sewing, n2 is the current rotating speed of the main motor of the sewing machine when the front edge of the sewing material passes through the third sensor, Tc₂Is the response time of the third inductor.

Further, a safe cutting time parameter Ta is prestored in the electric control module; when the front trimming cutting time T obtained by automatic calculation of the electronic control module is less than the safe cutting time parameter Ta, the electronic control module controls the trimming cutter assembly to execute the front trimming action according to the front trimming cutting time T; when the electric control module automatically calculates that the obtained front trimming line cutting time T is larger than or equal to the safe cutting time parameter Ta, the electric control module controls the trimming cutter assembly to execute the front trimming line action according to the safe cutting time parameter Ta.

As described above, the inductor switching control method according to the present invention has the following advantageous effects:

this application can select second inductor or third inductor as preceding trimming control usefulness according to sewing machine's running state autonomous identification, select the trimming before third inductor control under the sewing machine low-speed, the condition of little gauge needle sewing, select the trimming before the second inductor control under the sewing machine high-speed, the sewing machine condition of big gauge needle sewing to effectively avoid cutting cloth phenomenon when realizing the trimming effect of short thread end, trimming effect and sewing quality before guaranteeing.

Drawings

Fig. 1 is a schematic view of a sewing machine according to the present application.

Fig. 2 is a schematic structural view of an upper operation panel of the sewing machine according to the present application.

Fig. 3 is a schematic diagram of a first embodiment of a method for controlling switching of inductors in the present application.

Fig. 4 is a schematic diagram of a second embodiment of a method for controlling switching of inductors in the present application.

Fig. 5 is a schematic diagram of a third embodiment of a method for controlling switching of inductors in the present application.

Description of the element reference numerals

1 first inductor

2 second inductor

3 third inductor

4 fourth inductor

5-seam table

6 needle plate

7 trimming knife assembly

8 emitting assembly

9 operating panel

91 first function key

92 display screen

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

It should be understood that the structures, proportions, and dimensions shown in the drawings and described herein are for illustrative purposes only and are not intended to limit the scope of the present invention, which is defined by the claims, but rather by the claims. In addition, the terms such as "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for convenience of description only and are not intended to limit the scope of the present invention, and changes or modifications of the relative relationship thereof may be made without substantial technical changes and modifications.

The application relates to a sewing machine, which is provided with an electric control module, a thread cutting knife component 7 used for executing thread cutting action and an operation panel 9, wherein a thread cutting driving source and the operation panel 9 in the thread cutting knife component 7 are connected with the electric control module. As shown in fig. 1, a first sensor 1, a second sensor 2, a third sensor 3 and a fourth sensor 4 are further arranged in the sewing machine, and the first sensor 1, the second sensor 2, the third sensor 3 and the fourth sensor 4 are all connected with an electric control module, wherein the first sensor 1 is used for sewing and presser foot lifting control, the second sensor 2 and the third sensor 3 are used for front thread trimming control, and the fourth sensor 4 is used for rear thread trimming control; based on this, the first inductor 1, the second inductor 2, the third inductor 3 and the thread trimmer assembly 7 are sequentially arranged from back to front along the direction of forward cloth feeding of the sewing machine, and the fourth inductor 4 is arranged at the thread trimmer assembly 7. Still install emission subassembly 8 on sewing machine's the casing, emission source and first inductor 1, second inductor 2, third inductor 3 and fourth inductor 4 correlation from top to bottom in the emission subassembly 8, emission subassembly 8 links to each other with electronic control module, and electronic control module realizes opening or closing of first inductor 1, second inductor 2, third inductor 3 and fourth inductor 4 through opening or closing of emission source in the control emission subassembly 8. In another embodiment, the first inductor 1, the second inductor 2, the third inductor 3, and the fourth inductor 4 may also be single-reflection inductors, that is, one inductor has both a transmitting end and a receiving end, and no correlation is required, so that the influence of ambient light is avoided, and the cost is also reduced.

In the sewing process of the sewing machine, when the output signal of the second sensor 2 is from the existence to the nonexistence, the electric control module can judge that the front edge of the sewing material reaches the second sensor 2, namely the front edge of the sewing material passes through the second sensor 2; similarly, when the output signal of the third sensor 3 is from the presence to the absence, the electronic control module can judge that the front edge of the sewing material reaches the third sensor 3, namely, the front edge of the sewing material passes through the third sensor 3. Therefore, the electronic control module can judge whether the front edge of the sewing material passes through the second sensor 2 or the third sensor 3 according to the feedback signal of the second sensor 2 or the third sensor 3, so as to control the front trimming line cutting time T.

The invention provides a sensor switching control method, which is characterized in that a second sensor 2 or a third sensor 3 is automatically identified and selected according to the current running state of a sewing machine during front trimming control, preferably: the third sensor 3 is selected to control front trimming under the condition that the sewing machine sews at low speed and with small stitch distance, and the second sensor 2 is selected to control front trimming under the condition that the sewing machine sews at high speed and with large stitch distance. Specifically, as shown in fig. 3 to 5, the inductor switching control method according to the present application includes the following steps:

step S1, the second sensor 2 and the third sensor 3 are arranged, the third sensor 3 is closer to the thread cutting edge of the thread cutting knife assembly 7 than the second sensor 2, the second sensor 2 is installed on the sewing table 5 of the sewing machine, and the third sensor 3 is installed on the needle plate 6 of the sewing machine.

And step S2, presetting parameter threshold values in an electric control module of the sewing machine.

Step S3, when the sewing machine sews, the electric control module obtains the running state parameter of the sewing machine, the running state parameter is used for representing the needle pitch size or the sewing speed size when the sewing machine runs, the electric control module compares the running state parameter with the parameter threshold value and controls the front trimming cutting time T according to the comparison result:

when the electric control module judges that the operating state parameter is smaller than the parameter threshold value, the electric control module judges that the sewing machine is in a low-speed or small-needle-pitch operating state, the electric control module shields the feedback signal of the second inductor 2, and the electric control module controls the front trimming and feeding time T according to the feedback signal of the third inductor 3; in this case, when the electronic control module determines that the front edge of the sewn material passes through the third sensor 3 according to the feedback signal of the third sensor 3, the electronic control module starts timing, and controls the thread trimmer assembly 7 to perform a front thread trimming operation after the front thread trimming cutting time T is timed out, so as to cut off the front thread braid at the front edge of the sewn material, where the front thread trimming cutting time T is the first front thread trimming time T1 matched with the third sensor 3.

When the electric control module judges that the operating state parameter is more than or equal to the parameter threshold value, the electric control module judges that the sewing machine is in a high-speed or large-needle-pitch operating state, the electric control module shields a feedback signal of the third inductor 3, and the electric control module controls the front trimming and feeding time T according to the feedback signal of the second inductor 2; in this case, when the electronic control module determines that the front edge of the sewn material passes through the second sensor 2 according to the feedback signal of the second sensor 2, the electronic control module starts to time, and controls the thread trimmer assembly 7 to perform a front thread trimming operation after the front thread trimming cutting time T is timed out, so as to cut off the front thread braid at the front edge of the sewn material, where the front thread trimming cutting time T is the second front thread trimming time T2 matched with the second sensor 2.

This application can select second inductor 2 or third inductor 3 as preceding trimming control usefulness according to sewing machine's running state autonomous identification, at sewing machine low-speed, the trimming before selecting third inductor 3 control under the condition of little gauge sewing, at sewing machine high-speed, the trimming before selecting second inductor 2 control under the condition of big gauge sewing, thereby effectively avoid cutting cloth phenomenon when realizing the trimming effect of stub, trimming effect and sewing quality before guaranteeing.

In the step S3, the operation state parameter is used to represent the needle pitch size or the sewing speed when the sewing machine operates, so the operation state parameter can be a needle pitch parameter U, the parameter threshold is a needle pitch threshold X1, and is matched with the type of the needle pitch parameter U, and the needle pitch parameter U is the actual needle pitch value when the sewing machine sews; or, the running state parameter may be a motor rotation speed parameter W, and the motor rotation speed parameter W may directly represent the sewing speed, and then the parameter threshold is a sewing speed threshold X2, which is matched with the type of the motor rotation speed parameter W, and the motor rotation speed parameter W is the actual rotation speed of the main motor when the sewing machine sews.

Further, when the operating state parameter is the needle pitch parameter U, the electronic control module obtains the needle pitch parameter U in the following two ways. Firstly, before the sewing machine starts to sew, a stitch length parameter U is set by a user through an operation panel 9 on the sewing machine; the structure of the operation panel 9 is as shown in fig. 2, the operation panel 9 is provided with a first function key 91 and a display screen 92, a user enters a setting mode of a needle pitch parameter U after pressing the function key, the size of the needle pitch of the sewing machine during sewing can be set or adjusted, after subsequent sewing machine starts sewing, the electric control module can obtain the needle pitch parameter U set by the user according to feedback of the operation panel 9, the electric control module controls the sewing machine to operate according to the needle pitch parameter U, automatically matches and calculates the needle pitch parameter U and a needle pitch threshold value X1, and the second inductor 2 or the third inductor 3 is selected when front thread cutting is determined according to a matching result. In the second mode, the stitch length parameter U is automatically obtained by the electronic control module, namely the electronic control module automatically samples the actual stitch length value when the sewing machine sews; specifically, the operating panel 9 is provided with a second function key (P key) and a third function key (a < key) to enter a needle pitch automatic sampling mode, the electronic control module samples a voltage value V of the second sensor 2 and a rotating speed S of the main motor of the sewing machine when the front edge of the sewing material passes through the second sensor 2, the electronic control module automatically calculates a needle pitch parameter U according to f (V, S), the U is f (V, S), and f (V, S) is a function of the voltage value V of the second sensor 2 and the rotating speed S of the main motor of the sewing machine when the front edge of the sewing material passes through the second sensor 2. Preferably, when the second sensor 2 is covered by the seam material, the time for the second sensor 2 to detect the seam material is different, and further the voltage value V of the second sensor 2 is different, so that the electronic control module obtains the voltage compensation value V1 of the second sensor 2 according to the voltage value V of the second sensor 2; similarly, since the preset needle pitch value and the actual needle pitch value of the sewing machine during operation have deviation, the electronic control module obtains the rotation speed compensation value S1 of the main motor of the sewing machine at the moment according to the rotation speed S of the main motor when the front edge of the sewing material passes through the second inductor 2, and the needle pitch parameter U is obtained by the electronic control module through calculation according to the voltage compensation value V1 and the rotation speed compensation value S1: u is L K V1S 1/N, where L is the distance between the second inductor 2 and the third inductor 3, K is the conversion constant of the number of signal pulses and the number of pins of the main motor, and N is the number of signals of the main motor.

Further, for the front trimming cutting time T: the front trimming cutting time T includes a first front trimming time T1 for the electric control module to select the cutting time control when the third sensor 3 performs front trimming and a second front trimming time T2 for the electric control module to select the cutting time control when the second sensor 2 performs front trimming. The first front trimming time T1 and the second front trimming time T2 may be set values pre-stored in the electronic control module; alternatively, the first front trimming time T1 and the second front trimming time T2 may be automatically calculated and obtained by the electronic control module. Specifically speaking, when the sewing machine operates at a low speed and with a small needle pitch, the electric control module controls the front trimming cutting time T according to the feedback signal of the third sensor 3, namely: when the motor module judges that the front edge of the sewn material passes through the third sensor 3 according to the feedback signal of the third sensor 3, timing is started, and the thread trimming cutter assembly 7 is controlled to execute the front thread trimming action immediately after the first front thread trimming time T1 is timed out, wherein the calculation mode of the first front thread trimming time T1 is preferably: t1 ═ L2/(P × n2) -Tc₂Wherein, L2 is the distance between the third sensor 3 and the thread cutting edge of the thread cutting knife component 7, P is the current needle pitch when the sewing machine sews, namely the size of the needle pitch parameter U, n2 is the current rotating speed of the main motor in the sewing machine when the front edge of the sewing material passes through the third sensor 3, Tc₂Is the response time of the third inductor 3. When the sewing machine operates at high speed and large needle pitch, the electric control module controls the front trimming cutting time T according to the feedback signal of the second sensor 2, namely: when the motor module judges that the front edge of the sewn material passes through the second sensor 2 according to the feedback signal of the second sensor 2, timing is started, and the thread trimming cutter assembly 7 is controlled to execute the front thread trimming action immediately after the second front thread trimming time T2 is timed out, wherein the calculation mode of the second front thread trimming time T2 is preferably that T2 is L1/(P*n1)-Tc₁Wherein, L1 is the distance between the second sensor 2 and the thread cutting edge of the thread cutting knife component 7, P is the current needle pitch when the sewing machine sews, namely the size of the needle pitch parameter U, n1 is the current rotating speed of the main motor in the sewing machine when the front edge of the sewing material passes through the second sensor 2, Tc₁Is the response time of the second inductor 2.

Further, safety parameters are also prestored in the electric control module, and the safety parameters are preferably safety down cutting time parameters Ta; the safety lower cutter time parameter Ta includes a first safety lower cutter time parameter Ta1 matched with the third sensor 3 and a second safety lower cutter time parameter Ta2 matched with the second sensor 2, the first safety lower cutter time parameter Ta1 represents the time required for the front edge of the sewing material to pass through the third sensor 3 to the thread trimmer assembly 7, and the second safety lower cutter time parameter Ta2 represents the time required for the front edge of the sewing material to pass through the second sensor 2 to the thread trimmer assembly 7. When the sewing machine runs at a low speed and a small stitch length, the electric control module selects the third sensor 3 for front trimming control, and when the first front trimming time T1 obtained by automatic calculation of the electric control module is smaller than a first safe lower cutter time parameter Ta1, the electric control module controls the trimming cutter assembly 7 to execute front trimming action according to the first front trimming time T1; when the first front trimming time T1 obtained by the automatic calculation of the electronic control module is greater than or equal to the first safe cutting time parameter Ta1, the electronic control module controls the trimming cutter assembly 7 to execute the front trimming action according to the first safe cutting time parameter Ta 1. When the sewing machine runs at high speed and large needle pitch, the electric control module selects the second sensor 2 for front trimming control, and when the second front trimming time T2 obtained by automatic calculation of the electric control module is smaller than the second safe lower cutting time parameter Ta2, the electric control module controls the trimming cutter assembly 7 to execute front trimming action according to the second front trimming time T2; when the second front trimming time T2 obtained by the automatic calculation of the electronic control module is greater than or equal to the second safe cutting time parameter Ta2, the electronic control module controls the trimming cutter assembly 7 to execute the front trimming action according to the second safe cutting time parameter Ta 2. Of course, in other embodiments, the safety parameter may be the number of needles required for the material to pass through the sensor to the thread trimmer assembly 7.

Several preferred embodiments of the sensor switching control method are exemplified below.

As shown in fig. 3, an embodiment of the sensor switching control method includes the following steps:

step A1, the needle pitch threshold X1 is prestored in the electric control module.

Step A2, before sewing, the user sets the needle pitch parameter U through the operation panel 9 of the sewing machine.

Step A3, starting sewing, wherein the sewing machine runs at a stitch length of a stitch length parameter U; the electronic control module obtains a current needle pitch parameter U of the sewing machine, judges whether the needle pitch parameter U is smaller than a needle pitch threshold value X1 prestored in the electronic control module, and controls the following steps according to a judgment result:

if yes, the sewing machine is in a small-needle-pitch running state, and the electric control module shields the feedback signal of the second sensor 2; during front trimming, after the electric control module judges that the front edge of the sewing material reaches the position of the third inductor 3 according to the feedback signal of the third inductor 3, the electric control module automatically calculates the first front trimming time T1, wherein T1 is L2/(P x n2) -Tc₂Meanwhile, the electronic control module starts to time and controls the thread trimming cutter assembly 7 to execute the front thread trimming action after the first front thread trimming time T1 is timed out, and the front thread trimming is finished;

if not, the sewing machine is in a large-needle-pitch running state, and the electric control module shields the feedback signal of the third sensor 3; during front trimming, when the electric control module judges that the front edge of the sewing material reaches the position of the second sensor 2 according to the feedback signal of the second sensor 2, the electric control module automatically calculates the second front trimming time T2, wherein T2 is L1/(P n1) -Tc₁And simultaneously, the electronic control module starts to time and controls the thread trimming cutter assembly 7 to execute the front thread trimming action after the second front thread trimming time T2 is timed out, so that the front thread trimming is finished.

As shown in fig. 4, an embodiment of a method for controlling sensor switching includes the following steps:

and step B1, pre-storing a needle pitch threshold X1, a first safe cutting time parameter Ta1 and a second safe cutting time parameter Ta2 in the electric control module.

Step B2, before sewing, the user sets the needle pitch parameter U through the operation panel 9 of the sewing machine.

Step B3, starting sewing, wherein the sewing machine operates according to the stitch length of the stitch length parameter U; the electronic control module obtains a current needle pitch parameter U of the sewing machine, judges whether the needle pitch parameter U is smaller than a needle pitch threshold value X1 prestored in the electronic control module, and controls the following steps according to a judgment result:

if yes, the sewing machine is in a small-needle-pitch running state, and the electric control module shields the feedback signal of the second sensor 2; during front trimming, after the electric control module judges that the front edge of the sewing material reaches the position of the third inductor 3 according to the feedback signal of the third inductor 3, the electric control module automatically calculates the first front trimming time T1, wherein T1 is L2/(P x n2) -Tc₂Meanwhile, the electronic control module starts timing and compares the calculated first front trimming time T1 with a first safe cutting time parameter Ta1 prestored in the electronic control module, and when the first front trimming time T1 is smaller than the first safe cutting time parameter Ta1, the trimming cutter assembly 7 is controlled to execute front trimming actions after the first front trimming time T1 is timed; when the first front trimming time T1 is greater than or equal to the first safe cutting time parameter Ta1, controlling the trimming cutter assembly 7 to execute a front trimming action after the first safe cutting time parameter Ta1 is timed out, and ending the front trimming;

if not, the sewing machine is in a large-needle-pitch running state, and the electric control module shields the feedback signal of the third sensor 3; during front trimming, when the electric control module judges that the front edge of the sewing material reaches the position of the second sensor 2 according to the feedback signal of the second sensor 2, the electric control module automatically calculates the second front trimming time T2, wherein T2 is L1/(P n1) -Tc₁Meanwhile, the electronic control module starts to time and compares the calculated second front trimming time T2 with a second safe cutting time parameter Ta2 prestored in the electronic control module, and when the second front trimming time T2 is smaller than the second safe cutting time parameter Ta2, the trimming cutter assembly 7 is controlled to execute the front trimming action after the second front trimming time T2 is timed; when the second front trimming time T2 is greater than or equal to the second safe cutting time parameter Ta2, the second safe cutting time parameter Ta2 is timed to be over, and the trimming cutter assembly 7 is controlled to perform the front trimming operation, so that the front trimming operation is finished.

As shown in fig. 5, a third embodiment of the inductor switching control method includes the following steps:

and step C1, pre-storing a sewing speed threshold value X2, a first safe cutting time parameter Ta1 and a second safe cutting time parameter Ta2 in the electric control module.

Step C2, sewing; when the electric control module judges that the front edge of the sewing material reaches the second inductor 2 according to the feedback signal of the second inductor 2, the electric control module acquires the rotating speed S of the main motor of the sewing machine at the moment through sampling the signal of the main motor, marks the rotating speed S of the main motor of the sewing machine as a motor rotating speed parameter W, judges whether the motor rotating speed parameter W is smaller than a sewing speed threshold value X2 or not, and controls the following steps according to the judgment result:

if yes, the sewing machine is in a low-speed running state, and the electric control module shields the feedback signal of the second sensor 2; during front trimming, after the electric control module judges that the front edge of the sewing material reaches the position of the third inductor 3 according to the feedback signal of the third inductor 3, the electric control module automatically calculates the first front trimming time T1, wherein T1 is L2/(P x n2) -Tc₂Meanwhile, the electronic control module starts timing and compares the calculated first front trimming time T1 with a first safe cutting time parameter Ta1 prestored in the electronic control module, and when the first front trimming time T1 is smaller than the first safe cutting time parameter Ta1, the trimming cutter assembly 7 is controlled to execute front trimming actions after the first front trimming time T1 is timed; when the first front trimming time T1 is greater than or equal to the first safe cutting time parameter Ta1, the first safe cutting time parameter Ta1 is timed to be over, and the trimming cutter assembly 7 is controlled to perform the front trimming operation, so that the front trimming operation is finished.

If not, the sewing machine is in a high-speed running state, and the electric control module shields the feedback signal of the third sensor 3; during front trimming, when the electric control module judges that the front edge of the sewing material reaches the position of the second sensor 2 according to the feedback signal of the second sensor 2, the electric control module automatically calculates the second front trimming time T2, wherein T1 is L1/(P n1) -Tc₁And simultaneously, the electronic control module starts to time and compares the calculated second front trimming time T2 with a second safe cutting time parameter Ta2 prestored in the electronic control module, and when the second front trimming time T2 is less than the second safe cutting time parameter Ta2, the second front trimming time is timed to be fullControlling the thread trimmer assembly 7 to perform front thread trimming action after T2; when the second front trimming time T2 is greater than or equal to the second safe cutting time parameter Ta2, the second safe cutting time parameter Ta2 is timed to be over, and the trimming cutter assembly 7 is controlled to perform the front trimming operation, so that the front trimming operation is finished.

The fourth embodiment of the sensor switching control method: the difference between the first embodiment of the sensor switching control method and the second embodiment of the sensor switching control method is that the stitch length parameter U is automatically calculated by the electronic control module, so step a2 in the first embodiment of the sensor switching control method needs to be replaced with: before sewing is started, a user enters a stitch length automatic sampling mode through a second function key and a third function key on an operation panel 9; step a3 in the first embodiment of the sensor switching control method is replaced by: starting the sewing, the electric control module obtains a voltage compensation value V1 of the second inductor 2 and a rotating speed compensation value S1 of a main motor when the front edge of the sewing material passes through the second inductor 2, and automatically calculates a needle pitch parameter U: u is L × K × V1 × S1/N, and it is determined whether the pitch parameter U is smaller than a pitch threshold X1 pre-stored in the electronic control module, and the subsequent control is the same as the embodiment one of the sensor switching control method.

Fifth embodiment of the inductor switching control method: the difference between the second embodiment of the sensor switching control method and the second embodiment of the sensor switching control method is that the gauge parameter U is automatically calculated by the electronic control module, so step B2 in the second embodiment of the sensor switching control method needs to be replaced by: before sewing is started, a user enters a stitch length automatic sampling mode through a second function key and a third function key on an operation panel 9; step B3 in the second embodiment of the sensor switching control method is replaced with: starting the sewing, the electric control module obtains a voltage compensation value V1 of the second inductor 2 and a rotating speed compensation value S1 of a main motor when the front edge of the sewing material passes through the second inductor 2, and automatically calculates a needle pitch parameter U: u is L × K × V1 × S1/N, and it is determined whether the pitch parameter U is smaller than a pitch threshold X1 pre-stored in the electronic control module, and the subsequent control is the same as the embodiment one of the sensor switching control method.

Sixth embodiment of the inductor switching control method: the second inductor 2 or the third inductor 3 is directly set and selected through the operation panel 9, and when the second inductor 2 is selected, the lower cutter control during front trimming is carried out according to the second front trimming time T2; when the third sensor 3 is selected, the lower blade control at the time of front trimming is performed according to the first front trimming time T1.

In conclusion, the present invention effectively overcomes various disadvantages of the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.