JP2008220597A - Driving device of sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve both of an operation of a needle and a looper necessary for ravel prevention of a double chain stitch and of operations of a looper thread guide hook and a thread cutter hook related thereto in a simple constitution of a control system. <P>SOLUTION: This sewing machine 1 for double chain stitch having the looper thread guide hook 5 and the thread cutter hook 6 is so formed that, a sequence control part 7 attached to a sewing machine motor 2, or a drive source of a sewing machine main spindle 10, gives operation commands to the looper thread guide hook 5 and the thread cutter hook 6, and operates the looper thread guide hook 5 and the thread cutter hook 6 in connection with the rotation of the sewing machine main spindle 10 generated by the driving control of the sewing motor 2 to achieve the ravel prevention. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention implements a fraying prevention method for preventing the occurrence of fraying peculiar to the stitches of the double chain stitch formed by this sewing machine by including it in a double chain stitch sewing machine (including a flat stitch sewing machine). The present invention relates to a driving device for a sewing machine that can be used.

  FIG. 4 is a plan view of a double chain stitch seam formed by a double chain stitch machine or a flat stitch machine as viewed from the back side of the fabric. This seam has a shape shown in which the loops of the needle threads 8a and 8b and the looper thread 9 are entangled by other thread looping, and the end of the looper thread 9 cut at the end of the sewing is indicated by an arrow in the figure. When pulled as shown, the looper thread 9 is pulled out from the final loops 8c and 8d of the needle threads 8a and 8b, and such a slipping has a characteristic that it sequentially shifts toward the sewing start side.

  While this characteristic is useful for unraveling seams when sewing mistakes occur, it causes a problem that the seams are prone to fraying when using a sewn product, and therefore fraying to prevent this type of fraying from occurring. Various stopping methods have been proposed. As one of them, the applicant of the present invention provides a looper thread hook that holds the looper thread held by the looper, and stops the sewing operation by moving the looper to the left just before the end of the sewing, so that the loop of the needle thread is put together with the looper. A method has been proposed in which a looper thread that has been passed is held by a looper thread hook and a needle thread and a looper thread are cut after sewing one or more stitches in this state (see, for example, Patent Document 1).

  Further, the applicant of the present invention is inserted into the loop of the needle thread through which the looper is passed from the right side, catches the looper thread held at the tip of the looper by the hook at the tip, and the looper held by the looper thread hook by the halfway hook. A thread trimming hook that catches the thread together with the needle thread, pulls them back and cuts them together, and cuts the needle thread and looper thread after the execution of one or more stitches as described above is performed by the operation of this thread trimming hook. A method has also been proposed (see, for example, Patent Document 2).

  FIG. 5 is a plan view of a seam formed by performing these fraying prevention methods. According to the fraying prevention method described in Patent Documents 1 and 2, the looper thread 9 captured by the looper thread hook is the last of the needle threads 8a and 8b formed before the sewing is stopped, as shown in the figure. Seams entangled in the form of other thread lacing around the loops 8c and 8d are formed. The looper yarn 9 entangled in this way does not come out of the final loops 8c and 8d even if the end of the looper yarn 9 is pulled as indicated by an arrow, and reliably prevents fraying of the seam at the generation stage. In addition to providing a reliable fray-preventing effect, the stitches at the end of the stitch have no change in appearance from the other parts, and the appearance does not deteriorate.

Further, when the yarn is cut by the thread trimming hook described in Patent Document 2, the protruding ends of the looper yarn 9 from the final loops 8c and 8d are shortly aligned as shown by a two-dot chain line in FIG. This eliminates the need for handling the yarn ends.
Japanese Patent No. 2879399 JP 2006-314762 A

  As described above, the fraying prevention method proposed in Patent Documents 1 and 2 is an excellent method that can surely prevent fraying that occurs at the end of sewing at the seam of the double chain stitch. For this purpose, it is necessary to operate the aforementioned looper thread hook and thread trimming hook in relation to the vertical movement of the needle holding the needle thread and the forward / backward movement of the looper holding the looper thread.

  The present invention has been made in view of such circumstances, and the operation of the needle and looper necessary for preventing fraying of the stitches of the double chain stitch, and the looper threading hook and thread trimming hook related thereto are related. It is an object of the present invention to provide a sewing machine drive device that can realize the operation with a simple control system configuration.

  According to a first aspect of the present invention, there is provided a sewing machine drive device comprising: the looper on a sewing machine that forms a double chain stitch by a vertical movement of a needle and a horizontal movement of a looper that are generated in synchronization with each other by transmission from a sewing machine motor. A looper thread hook that holds the looper thread held on the looper thread, a looper thread held on the looper thread hook and a thread trimming hook that catches and cuts the needle thread held on the needle, Before the end of sewing for forming the sewing machine, the operation of one or more stitches of the needle and the looper is performed in combination with the operations of the looper thread hook and the thread trimming hook so as to realize fraying prevention at the sewing end portion. The looper thread hook is attached to a sequence control unit which is attached to the sewing machine motor and performs drive, stop control and speed control operations of the sewing machine motor. Characterized in that are recorded a control procedure for operating the fine thread cutting hook.

  In the sewing machine drive device according to the second invention of the present invention, the control procedure in the first invention is a procedure in which the operating speed of one or more stitches of the needle and looper is changed according to the operating speed before the end of the sewing. It is characterized by including.

  In the sewing machine driving device according to the present invention, the operation of the looper yarn hooking hook and the thread trimming hook provided for preventing fraying is provided with the sequence control unit attached to the sewing machine motor in which the control program for the sewing operation is written. Since it is also used as a control means for control, a fraying prevention method can be realized with a simple configuration.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. FIG. 1 is a schematic block diagram of a sewing machine provided with a drive device according to the present invention.

  The illustrated sewing machine 1 includes a sewing machine main shaft 10 that rotates by belt transmission from a sewing machine motor 2, and a needle bar drive shaft 11 that rotates by belt transmission from the sewing machine main shaft 10. The sewing machine main shaft 10 is rotatably supported inside the sewing machine bed 12 and is configured to be transmitted to a looper drive mechanism 3 built in the front end of the sewing machine bed 12. The needle bar drive shaft 11 is installed inside a sewing machine arm 13 extending in parallel above the sewing machine bed 12, and is configured to transmit to a needle bar drive mechanism 4 provided at the tip of the sewing machine arm 13. Yes.

  The looper drive mechanism 3 is a mechanism for moving the looper 30 provided inside the sewing machine bed 12 to the left and to the right according to the rotational transmission from the sewing machine main shaft 10. The needle bar drive mechanism 4 is a mechanism that moves up and down according to the rotational transmission from the needle bar drive shaft 11 together with the needle 40 attached to the lower end of the needle bar 41 suspended from the tip of the sewing machine arm 13. These mechanisms 3 and 4 are all known mechanisms, and are schematically shown as functional blocks at respective positions in FIG.

  A looper thread hook 5 and a thread trimming hook 6 are arranged in the vicinity of the looper driving mechanism 3 inside the sewing machine bed 12. As disclosed in Patent Document 1 or Patent Document 2 described above, the looper thread hook 5 and the thread trimming hook 6 advance and retract independently from each other with respect to the intersection of the looper 30 and the needle 40 inside the sewing machine bed 12. In FIG. 1, the hooks are schematically shown as functional blocks together with air cylinders serving as respective drive sources. In FIG. 1, the looper thread hook 5 and the thread trimmer hook 6 are shown on the opposite side of the looper drive mechanism 3 across the vertical movement position of the needle 40. The actual arrangement of the thread trimming hook 6 is not shown.

  A sequence control unit 7 is attached to the sewing machine motor 2 as a driving source of the sewing machine 1 as described above. The sequence control unit 7 includes a CPU, a ROM, and a RAM, and is a control unit that performs a control operation for driving the sewing machine motor 2 by an operation of the CPU according to a control program written in advance in the ROM.

  The output of the sequence control unit 7 is given to the sewing machine motor 2 to be controlled through the motor drive circuit 20, and the sewing machine motor 2 is operated by the operation of the motor drive circuit 20 according to the operation command given from the sequence control unit 7. It is configured to be driven and stopped and to increase / decrease the rotational speed.

  The sequence control unit 7 is given a detection result of the rotational position of the sewing machine main shaft 10 from a main shaft rotation position detector 14 attached to the sewing machine main shaft 10. This detection result is information indicating the operating positions of the looper driving mechanism 3 and the needle bar driving mechanism 4 that perform the above-described operations in accordance with the rotation of the sewing machine spindle 10, that is, the forward / backward position of the looper 30 and the vertical movement position of the needle 40. Used for driving and stopping control of the sewing machine motor 2.

  The sequence control unit 7 is given a detection result of the rotational position of the sewing machine motor 2 via a motor drive circuit 20 from a motor rotation sensor 21 attached to the sewing machine motor 2. This detection result is used to calculate the rotational speed of the sewing machine motor 2, that is, the operating speed of the sewing machine 1, and the calculated operating speed is used as feedback information when controlling the speed of the sewing machine motor 2. This is used to determine the speed of the fraying stop operation described later.

  Further, a stepping signal and a stepping signal are given to the sequence control unit 7 from a stepping pedal 15 that is stepped on and stepped back for operating the sewing machine 1. These signals are used as trigger signals for driving and stopping the sewing machine motor 2 and fraying prevention operation described later. The depression signal includes the depression amount of the foot pedal 15, and the sewing machine motor 2 is driven at a speed corresponding to the depression amount.

  In the sewing machine driving apparatus according to the present invention, the output of the sequence control unit 7 provided for controlling the driving of the sewing machine motor 2 is supplied to the looper thread hook 5 and the thread trimming hook 6 as separate drive circuits 50 and 60. Is given through. The looper thread hook 5 and the thread trimming hook 6 perform one advance / retreat operation in response to an operation command given from the sequence control unit 7 at a predetermined timing when fraying prevention described later is performed.

  As described above, the looper thread hook 5 and the thread trimming hook 6 include an air cylinder as a drive source, and can be configured to advance and retract according to supply and discharge of the operating pressure to the air cylinder. In this case, the drive circuits 50 and 60 are excitation circuits that excite and demagnetize the solenoid valves provided in the supply and discharge passages for different operating pressures for opening and closing. The looper thread hook 5 and the thread trimming hook 6 can also be configured using other driving sources such as an electromagnetic cylinder.

  The sequence control unit 7 further ends from the start of sewing, such as an air wiper for wiping the cut needle thread onto the sewing bed 12 and a presser foot cylinder for raising and lowering the presser foot that holds the sewing cloth on the sewing bed 12. However, in the following description, the looper thread hook 5 and the thread trimmer that are minimally necessary for preventing fraying can be used. A control operation for the hook 6 will be described.

  Sewing by the sewing machine 1 is executed by depressing the foot pedal 15. In this case, as described above, the sequence control unit 7 performs a control operation of driving the sewing machine motor 2 at a speed corresponding to the depression amount of the foot pedal 15. This control operation is performed by feedback control based on the deviation between the rotational speed of the sewing machine motor 2 calculated using the detection result of the motor rotation sensor 21 and the depression amount of the foot pedal 15, and the looper drive by transmission from the sewing machine spindle 10 is performed. The operation of the mechanism 3 and the operation of the needle bar drive mechanism 4 by transmission from the needle bar drive shaft 11 occur at a speed corresponding to the depression amount of the foot pedal 15, and the forward / backward movement of the looper 30 and the vertical movement of the needle 40 Thus, the fabric fed onto the sewing machine bed 12 is sewn at a desired speed.

  The sequence control unit 7 performs the following fraying prevention operation after the end of the above sewing in order to prevent the fraying from occurring at the sewing end portion. FIG. 2 is a time chart showing the operation content of the sequence controller 7 for preventing fraying.

The sequence control unit 7, after the required sewing is finished with respect to the sewing fabric, not shown, is returned to the neutral state from a state foot pedal 15 depression at T ₁ time of 2, none of the depression signal and stepping-back signal Is not given, a stop command is issued to the sewing machine motor 2 to stop the sewing machine 1 temporarily. This temporary stop is executed with reference to the rotational position of the sewing machine main shaft 10 given from the main shaft rotational position detector 14, with the needle 40 near the top dead center and the looper 30 near the left end.

Then the sequence control unit 7 waits until foot pedal 15 is depressed flashing operation, depressing-back operation at T ₂ the time of FIG. 2 is made, for implementing the fray stop as a trigger that is given stepped-back signal The following operations are performed. Needless to say, when the sewing is temporarily interrupted, the next step pedal 15 is resumed in response to the depression operation.

In FIG. 2, the foot pedal 15 is maintained in a neutral state from the time T _{1 to the} time T _2. However, maintaining such a neutral state is not an essential operation. 15 may be operated so as to shift from the depressed state to the depressed state through the neutral state. In this case, the sequence control unit 7 once realizes a state in which the hands 2 and 2 are in the vicinity of the top dead center and the looper 1 is in the vicinity of the leftward end, and starts the following operation.

In order to prevent fraying, the sequence control unit 7 first issues an operation command to the looper thread hook 5 to move the looper thread hook 5 forward and backward so that the looper thread held by the looper 30 at the left end is removed. Capture and hold. Then the sequence control unit 7, the T ₃ time points 2, issues an operation command to the sewing machine motor 2 with reference to the rotational position of the main shaft 10 provided from the spindle rotation position detector 14, by the looper thread hanging hook 5 While holding the looper thread, one or more stitches are sewn, the needles 2 and 2 return to the vicinity of the top dead center, and the looper 1 returns to the vicinity of the leftward end to stop the sewing machine 1 again.

  After this re-stop, the sequence control unit 7 issues an operation command to the thread trimming hook 6 and causes the thread trimming hook 6 to move forward and backward. By this advance / retreat operation, the thread trimming hook 6 catches at least the looper thread held by the looper thread hook 5 and the needle thread through which the looper 30 located at the leftward end is inserted, and pulls it back to retract and cut it. At the same time, the cut looper yarn is held on the side continuous with the looper 30.

  As a result of the series of operations of the sequence control unit 7 as shown in FIG. 5, the looper thread 9 is placed in the final loops 8c and 8d of the needle threads 8a and 8b formed before the sewing is stopped, as shown in FIG. As a result, a seam entangled with each other is formed, and fraying of the seam can be reliably prevented at the generation stage. The positional relationship among the looper 30, the needle 40, the looper thread hook 5 and the thread trimmer hook 6 during the above operations is described in the above-mentioned Patent Documents 1 and 2 by the applicant of the present application, and detailed description thereof is omitted. .

  In the sewing machine driving device according to the present invention, one or more stitches performed by operating the looper 30 and the needle 40 to prevent fraying, and the looper thread hook 5 and the thread before and after the sewing are performed. The forward / backward movement of the cutting hook 6 is executed by the sequence control unit 7 attached to the sewing machine motor 2 as a drive source for the looper 30 and the needle 40.

  This is done by writing a program for executing the above control operation in the ROM of the sequence control unit 7 and assigning the looper thread hook 5 and the thread trimming hook 6 to the output port of the sequence control unit 7. Achieved. The operation signal of the foot pedal 15 given as an input to the sequence control unit 7 and the detection signals of the spindle rotation position detector 14 and the motor rotation sensor 21 are sewing motors for sewing that are the original purposes of the sequence control unit 7. 2 is a signal necessary for driving, stopping, and speed control, and it is not necessary to add new detection means for realizing fraying prevention.

  In the fraying prevention operation described above, the speed of the sewing operation performed with the looper thread held by the looper thread hook 5 is preferably changed according to the speed during normal sewing. FIG. 3 is a flowchart showing the operation content of the sequence control unit 7 for such speed change.

  The operation shown in this figure is started on the condition that the foot pedal 15 is returned from the depressed state to the neutral state after the sewing operation is finished, and the sewing machine 1 is temporarily stopped. It is determined whether or not a stepping operation is performed (step 1). If the stepping operation is not performed (step 1: NO), the presence / absence of the stepping operation is determined (step 2). If the stepping operation is not performed (step 2: NO), the stepping operation is performed. stand by.

  If a stepping operation is performed during this standby (step 2: YES), the fraying stop operation is terminated without performing the following processing. In this case, as described above, the normal sewing operation is resumed.

  When the foot pedal 15 is turned back (step 1: YES), the sewing speed before the temporary stop is compared with a predetermined speed N (step 3). The sewing speed is the rotational speed of the sewing machine spindle 10 calculated from the detection result of the spindle rotation position detector 14. The sewing speed before the temporary stop used for the comparison in step 3 is, for example, the sewing machine spindle 10 before the stop. The average value of the rotation speed during several rotations can be used.

  If it is determined by the comparison in step 3 that the sewing speed before the temporary stop exceeds the predetermined speed N (step 3: YES), the sewing speed is set to a speed n sufficiently smaller than the predetermined speed N. When set (step 4), the fraying prevention operation described above is performed under the restriction by the speed n (step 5), and when it is determined that the sewing speed before the temporary stop is equal to or lower than the predetermined speed N (step 3). : NO), the fraying stop operation is performed without limiting the sewing speed (step 5).

  The predetermined speed N used for the comparison in step 3 and the speed n set in step 4 are given as constants written in advance in the RAM of the sequence control unit 7. For example, if the speed N is 1000 rpm and the speed n is 200 rpm, when the sewing speed of the sewing machine 1 before the temporary stop exceeds 1000 rpm, that is, while maintaining a high sewing speed. When the temporary stop is made, the sewing operation for one stitch performed as described above in the subsequent fraying stop operation is performed at a speed limited to 200 rpm.

  When a temporary stop is made while maintaining a high sewing speed, the loop of the needle thread remaining after the needle 40 has moved to the top dead center is in a state in which it has become loose due to the action of inertia. By the operation of the sequence control unit 7 according to the flowchart of FIG. 3, the fraying prevention operation when the needle thread is loosened is performed at a limited speed, and the seam shown in FIG. 5 can be reliably realized. . The sewing operation at the limited speed is an operation for one or several stitches performed with the looper yarn hooking hook 5 holding the looper yarn, and there is no possibility of reducing the efficiency of the entire sewing operation.

  Note that the predetermined speed N that is a threshold value in the comparison in step 3 can be configured to be changed from the outside by operating a variable knob connected to the input side of the sequence control unit 7, for example. In this case, more reliable fraying prevention can be realized by changing the variable knob in accordance with the sewing conditions such as the type of sewing fabric, the hardness of the thread, or the quality of the finished state.

It is a typical block diagram of a sewing machine provided with the drive device concerning the present invention. It is a time chart which shows the operation content of the sequence control part for fraying prevention. It is a flowchart which shows the operation | movement content of the sequence control part for a speed change. It is the top view which looked at the seam of double ring stitch from the back side of cloth. It is a top view of the seam formed by implementation of a fray prevention method.

Explanation of symbols

1 Sewing Machine 2 Sewing Machine Motor 5 Looper Thread Hook 6 Thread Trim Hook 7 Sequence Controller
30 loopers
40 needles

Claims (2)

A looper thread hook that holds the looper thread held by the looper on a sewing machine that forms a double chain stitch seam by the vertical movement of the needle and the left / right movement of the looper that are generated in synchronization with each other by transmission from the sewing machine motor; A looper thread held by the looper thread hook and a thread trimming hook for catching and cutting the needle thread held by the needle, and before the end of sewing for forming the seam, the needle and In the driving device of the sewing machine that operates to achieve one or more looper stitches in combination with the looper thread hook and the thread trimming hook, and realizes fraying prevention at the sewing end.
A control procedure for operating the looper thread hook and the thread trimming hook is recorded in a sequence control unit attached to the sewing machine motor and performing drive, stop control and speed control operations of the sewing motor. Sewing machine drive device.   The sewing machine driving apparatus according to claim 1, wherein the control procedure includes a procedure of changing an operation speed of one or more stitches of the needle and the looper according to an operation speed before the end of the sewing.

Images