JP3876016B2 - Thread trimming method and apparatus for sewing machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thread trimming method and apparatus for performing thread trimming before the start of sewing of a sewing machine, and more particularly to a thread trimming method and apparatus for a sewing machine that can prevent a bird's nest of thread at the start of sewing.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, sewing machines, particularly industrial sewing machines, that are provided with a thread cutting device that automatically cuts upper and lower threads after sewing are frequently used for reasons such as improving sewing efficiency.
[0003]
Such a conventional thread cutting device for a sewing machine cuts an upper thread and a lower thread by, for example, making a movable blade and a fixed blade that can be contacted and separated freely move forward and backward with respect to the vertical movement path of the needle. .
[0004]
Further, in a sewing machine equipped with a conventional thread cutting device, as shown in FIG. 15, an upper thread 3a and a lower thread 3b at the start of sewing are entangled with a stitch 2 formed on, for example, a fabric 1 as a sewing product. Therefore, there is a problem that both the upper thread 3a and the lower thread 3b at the start of sewing are in a so-called bird's nest 4 state.
[0005]
In order to cope with such a problem, a wiper clamp that holds and captures the upper thread 3a at a position between the needle and the fabric 1 is provided, and this wiper clamp holds the wiper clamp at the start of sewing. It can be considered that the upper end 3a is cut by a sewing material presser having a knife for cutting the yarn end.
[0006]
That is, the sewing operation for sewing the upper thread 3a hung on the needle and the lower thread 3b entangled with the upper thread 3a into the fabric 1a is finished, and the upper and lower threads 3 are cut using a thread cutting device under the needle plate. After that, the upper thread 3a located between the cloth 1 and the needle located above the needle plate is captured and held by the wiper clamp, and when the sewing operation is started in this state, the needle moves up and down. The fabric 1 is fed to form the seam 2 on the fabric 1a, and the fabric 1 is fed about 3 to 4 stitches at the start of sewing of the upper thread 3a held by the wiper clamp (progressed). ) A configuration in which cutting is performed with a knife provided on the sewing material presser at the position is conceivable.
[0007]
[Problems to be solved by the invention]
However, in the case of the configuration in which the upper thread 3a is held by the wiper clamp, as shown in FIG. 16, the upper thread 3a at the start of sewing is cut to prevent bird's nest by the upper thread 3a at the start of sewing. Although the lower thread 3b at the start of sewing is not cut, the lower thread 3b at the start of sewing is sewn into the seam 2, and the lower thread 3b at the start of sewing becomes the bird's nest 4a. There is a problem that the quality of the sewing product may be deteriorated.
[0008]
The present invention has been made in view of these points, and provides a thread trimming method and apparatus for a sewing machine that can improve the quality of a sewing product by preventing the formation of a bird's nest by a thread at the start of sewing. Objective.
[0009]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the thread trimming method of the sewing machine according to claim 1 of the present invention is characterized in that an upper thread located above a needle plate is captured before the start of sewing and the thread end thereof is captured. In this state, the sewing machine is driven by one stitch, the lower thread end is positioned above the needle plate, the lower thread located above the needle plate is captured, and the thread end is already held. The upper end of the upper thread and the lower thread are held together and sewing is started in this state, and the thread ends of the upper thread and the lower thread at the start of sewing are cut in conjunction with the sewing operation.
[0010]
The thread trimming device of the sewing machine according to claim 2 of the present invention is characterized in that the sewing material presser having a knife for cutting the thread and the thread positioned above the needle plate can be held. The thread holding means and the thread holding means are driven before sewing is started, the upper thread located above the needle plate is captured and the thread end is held by the thread holding means, and the sewing machine is driven by one stitch in this state. Then, the thread end of the lower thread is positioned above the needle plate, and after the driving of the sewing machine for one stitch is finished, the thread holding means is driven to catch the lower thread positioned above the needle plate, and the thread The yarn holding means and the control means for driving the sewing machine are provided so that the yarn holding means holds the end together with the yarn end of the upper yarn already holding the end.
[0011]
Further, the thread trimming device for a sewing machine according to the third aspect of the present invention is characterized in that, in the second aspect, the control means is the first after the yarn holding means holds the upper thread and the lower thread. The feed pitch of the first stitch Than normal seam spacing The point is to control it small.
[0012]
Then, by operating the thread trimming device of the sewing machine according to the sewing thread trimming method of the present invention, it is possible to cut the upper thread and the lower thread at the start of sewing, The quality of the sewn product can be improved by preventing the bird's nest caused by the lower thread. Further, by controlling the feed pitch of the first stitch after the upper and lower threads are held by the thread holding means to be small, the interval between the first stitches can be reduced and the quality of the sewing product can be further improved. .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to embodiments shown in the drawings. In addition, about the structure which is the same as that of the conventional thing mentioned above, or equivalent, the same code | symbol is attached | subjected in drawing, and the description is abbreviate | omitted.
[0014]
1 to 3 show a main part of an example of an embodiment of a thread trimming device for a sewing machine according to the present invention to which the thread trimming method of the sewing machine according to the present invention is applied. FIG. 1 is a perspective view of the main part. And the figure 2 Is a plan view of the sewing product presser, and FIG. 3 is a block diagram of the control means.
[0015]
As shown in FIG. 1, a thread trimming device (hereinafter simply referred to as a thread trimming device) 5 of a sewing machine according to the present embodiment includes an upper thread 3a hung on a needle 6 and a lower thread entangled with the upper thread 3a. 3b is sewn into, for example, the fabric 1 as a substantially sheet-like sewing product, and a series of stitches is completed, and the thread 3 (the thread 3 is a generic term for the upper thread 3a and the lower thread 3b) is placed under the needle plate 7. It is provided in a general sewing machine 8 that cuts at a point.
[0016]
The thread trimming device 5 includes a thread holding means 9 capable of holding the thread 3, a sewing material presser 10 capable of cutting the thread 3 at the start of sewing, which is located on the side of the needle 6 of the fabric 1 in accordance with a sewing operation, and sewing. Control means 11 for controlling the operation of the thread holding means 9 and the operation of the sewing machine 8 in association with each other so as to cut the starting thread 3 is provided.
[0017]
The thread holding means 9 pays the thread 3 positioned above the needle plate 7, more specifically, the thread 3 positioned between the needle 6 positioned above the needle plate 7 and stopped and the fabric 1. A wiper 12 to be captured and a clamp 13 for holding the yarn 3 captured by the wiper 12 are provided.
[0018]
The wiper 12 is supported at the base end thereof by a rotating shaft 14 disposed on a sewing machine body 8a that can be driven by an actuator (not shown) such as a solenoid, and a hook 12a at the front end (free end) The thread 3 located above the needle plate 7 is captured, and the thread end of the thread 3 can be guided to a suction hole 15 described later of the clamp 13. That is, the hook 12 a of the wiper 12 can reciprocate at least between the suction hole 15 of the clamp 13 and the thread 3 located above the needle plate 7.
[0019]
The clamp 13 has a clamp body 13a formed in a substantially cylindrical shape as a whole. A suction hole 15 that sucks the yarn end side of the yarn 3 captured by the hook 12a of the wiper 12 is formed at one end of the clamp body 13a. A negative pressure path 16 communicating with the suction hole 15 and communicating with a negative pressure source (not shown) is formed inside the clamp body 13a. A spherical ball body 17 is disposed in the negative pressure path 16. The ball body 17 is attached to the tip of the output shaft 18a of the clamping cylinder 18 disposed at the other end of the clamp body 13a. The ball body 17 advances and retracts the output shaft 18a of the clamping cylinder 18. By doing so, the suction hole 15 is contacted and separated from the opposite side of the suction hole 15.
[0020]
That is, the clamp 13 sucks the yarn end of the yarn 3 carried by the hook 12 a at the tip of the wiper 12 into the negative pressure path 16 and sucks the yarn 3 sucked into the negative pressure path 16 into the suction hole 15. And the ball body 17 so that the yarn end of the yarn 3 can be held.
[0021]
The sewing product presser 10 can press the fabric 1 placed on the upper surface of the needle plate 7 from above, and the sewing product presser 10 cuts the thread 3 as shown in FIG. A scalpel 19 is provided. Then, when the fabric 1 is fed and advanced by a sewing operation in which the upper thread 3a hung on the needle 6 of the sewing machine 8 and the lower thread 3b entangled with the upper thread 3a are sewn into the cloth 1, the cloth 1 is formed. At the position where the seam 2 approaches the knife 19 of the work clamp 10 and the cloth 1 has advanced about 3 to 4 stitches as will be described later, the thread 3 at the start of sewing located on the needle 6 side of the cloth 1 is attached to the cloth 1. The upper part can be cut.
[0022]
The control means 11 is disposed at a desired position of the sewing machine body 8a. This control means 11 is for controlling the operation of each part of the thread holding means 9 and the sewing machine 8, and as shown in FIG. 3, a memory formed by at least a CPU 20 and an appropriate capacity ROM, RAM or the like. 21 and various drivers (controllers) 22 for driving the yarn holding means 9 and each part of the sewing machine 8.
[0023]
In the memory 21, a data storage area 21a for storing at least various types of input data and detection signals, a program storage area 21b for storing various programs, and control commands for each part of the thread trimming device 5 and the sewing machine 8 are stored. An output data storage area 21c for storing various output data such as is provided. The program storage area 21b captures at least the thread trimming program for carrying out the thread trimming method of the present invention, that is, the upper thread 3a positioned above the needle plate 7 before the start of sewing, and the thread. In this state, the sewing machine 8 is driven by one stitch so that the thread end of the lower thread 3b is positioned above the needle plate 7, and the lower thread 3b positioned above the needle plate 7 is captured. The thread end is held together with the thread end of the upper thread 3a already held, and sewing is started in this state, and the thread end of the thread 3 at the start of sewing of the upper thread 3a and the lower thread 3b is interlocked with the sewing operation. And the feed pitch of the first first fabric 1 after the thread holding means 9 holds the upper thread 3a and the lower thread 3b, that is, the first stitch 2 when the sewing operation is started. The interval L (see FIG. 11) of And programs that may have been stored.
[0024]
Next, the operation of the above-described sewing thread trimming device will be described with reference to FIGS.
[0025]
FIG. 4 is a flowchart showing an example of the embodiment of the thread trimming method of the sewing machine according to the present invention, and FIGS. 5 to 9 show the thread trimming of the sewing machine according to the present invention to which the thread trimming method of the sewing machine according to the present invention is applied. FIG. 5 is an explanatory view showing the operation state of the apparatus in order, FIG. 5 is an explanatory view showing a state where sewing is finished and the upper and lower threads are cut under the needle plate, and FIG. 6 is an explanatory view showing a state where the clamp holds the upper thread. 7 is an explanatory view showing a state in which the sewing machine is driven by one stitch and the lower thread is positioned above the needle plate, FIG. 8 is an explanatory view showing a state in which the hook of the wiper has caught the lower thread, and FIG. FIG. 10 is an explanatory view showing a state in which the upper and lower threads are held together, FIG. 10 is an explanatory view showing a state immediately before cutting of the thread at the start of sewing accompanying the sewing operation, and FIG. 11 is cutting the thread at the start of sewing. It is explanatory drawing which expands and shows the sewing state after having performed.
[0026]
For the sake of explanation, the flowchart shown in FIG. 4 will be mainly used, and description will be made with reference to FIGS.
[0027]
The thread trimming operation at the start of sewing in the sewing machine 8 provided with the thread trimming device 5 of the present embodiment is first started by the operator performing initial setting in step ST10. The initial setting in this step ST10 includes at least set values such as the type and thickness of the fabric 1 as a sewing product, the set values such as the type and count of the material of the thread 3 (upper thread 3a and lower thread 3b) to be used, thread Necessary for performing sewing such as the set value of the interval L (see FIG. 11) of the stitches 2 as the feed pitch of the first first fabric 1 after the holding means 9 holds both the upper thread 3a and the lower thread 3b. Various types of input data are performed by operating desired input devices (not shown) such as touch keys, dials, and keyboards. The various input data that has been input is stored in the data storage area 21 a of the memory 21 of the control means 11. Further, the CPU 20 of the control means 11 appropriately controls various drivers 22 for driving the yarn holding means 9 and each part of the sewing machine 8 based on the input data inputted and various programs stored in advance. Are calculated and stored in the output data storage area 21 c of the memory 21. Various output data stored in the output data storage area 20c are sequentially output along with the sewing operation.
[0028]
Next, in step ST20, it is determined whether an activation command signal for the sewing machine 8 has been input. This activation command signal is input by, for example, an operation in which an operator steps on a foot pedal (not shown). If the determination in step ST20 is NO (no input), the current state is maintained until the start command signal is input. If the determination in step ST20 is YES (input), the next step Proceeding to ST30, an upper thread holding operation for cutting the thread 3 at the start of sewing is started.
[0029]
At the start of the operation for cutting the thread 3 at the start of sewing, as shown in FIG. 5, the sewing machine 8 has finished sewing and stopped with the upper and lower threads 3 cut under the needle plate 7. The needle 6 is positioned above the needle plate 7 and stops, and only the upper thread 3a is located above the needle plate 7, more specifically, between the needle 6 and the fabric 1 that is the sewing product. . Further, in the clamp 13 constituting the yarn holding means 9, no negative pressure is supplied to the negative pressure path 16, the clamping cylinder 18 is driven positively, and the output shaft 18a of the clamping cylinder 18 contracts to the retracted end. And the ball body 17 is separated from the suction hole 15. Furthermore, in the wiper 12 constituting the yarn holding means 9, the hook 12 a is closest to the suction hole 15 of the clamp 13.
[0030]
Next, in step ST30, an upper thread holding operation for cutting the thread 3 at the start of sewing is performed. In this upper thread holding operation, the wiper 12 of the thread holding means 9 is driven in step ST31, negative pressure is supplied to the negative pressure path 16 of the clamp 13 of the thread holding means 9 in step ST32, and the thread holding means 9 is set in step ST33. This is performed by reversely driving the clamping cylinder 18 and stopping the supply of the negative pressure to the negative pressure path 16 of the clamp 13 of the yarn holding means 9 in step ST34. When the upper yarn holding operation is completed, the next step ST40 is performed. Proceed to
[0031]
The upper thread holding operation will be further described.
[0032]
The drive of the wiper 12 in the step ST31 is arranged in the sewing machine body 8a that drives an actuator (not shown) based on a control command sent from the control means 11 and supports the base end of the wiper 12. This is done by rotating the rotating shaft 14.
[0033]
That is, the wiper 12 is driven by moving the hook 12a of the wiper 12 from the standby position indicated by the solid line in FIG. 5 to the operating position indicated by the imaginary line in FIG. Then, it is performed by returning to the standby position.
[0034]
The hook 12a of the wiper 12 wipes off the upper thread 3a located above the needle plate 7 while the wiper 12 moves from the standby position toward the operating position, and the wiper 12 moves from the operating position toward the standby position. In the middle of returning, the upper thread 3a located above the needle plate 7 is hooked and captured, and when the hook 12a of the wiper 12 returns to the standby position, the thread end of the upper thread 3a is detached from the fabric 1 and the clamp 13 Located in the vicinity of the suction hole 15.
[0035]
In step ST32, the negative pressure is supplied to the negative pressure path 16 of the clamp 13 of the yarn holding means 9 based on a control command sent from the control means 11, for example, the negative pressure path 16 is a negative pressure source such as a vacuum pump. When directly connected to (not shown), the negative pressure source is driven, and the negative pressure path 16 is connected to a chamber (not shown) via a control valve (not shown). In this case, the control valve is opened.
[0036]
When negative pressure is supplied to the negative pressure path 16 of the clamp 13 of the thread holding means 9, the thread end of the upper thread 3a located near the suction hole 15 is sucked by the hook 12a of the wiper 12 in step ST31. It passes through the hole 15 and is sucked into the negative pressure path 16.
[0037]
In the reverse drive of the clamping cylinder 18 of the yarn holding means 9 in the step ST33, the tip of the output shaft 18a of the clamping cylinder 18 located at the retracted end is extended based on a control command sent from the control means 11. This is done by driving toward the forward end.
[0038]
When the clamping cylinder 18 is reversely driven, the output shaft 18a of the clamping cylinder 18 located at the retracted end reaches the forward end, and when the tip of the output shaft 18a reaches the forward end, the tip of the output shaft 18a. Is attached to the suction hole 15 via the upper thread 3 a, and as a result, the thread end of the upper thread 3 a is held by the clamp 13.
[0039]
Stopping the supply of negative pressure to the negative pressure path 16 of the clamp 13 of the yarn holding means 9 in step ST34 is opposite to supplying negative pressure to the negative pressure path 16 of the clamp 13 of the thread holding means 9 in step ST32. It is performed with the operation.
[0040]
When the supply of the negative pressure to the negative pressure path 16 of the clamp 13 of the thread holding means 9 is stopped, there is no force to suck the upper thread 3a into the negative pressure path 16, but the thread of the upper thread 3a Clamp 13 The state held in is continued.
[0041]
FIG. 6 shows a state where the upper thread holding operation is finished and the clamp 13 holds the upper thread 3a. Further, the thread trimming device 5 shown in FIG. 1 also shows a state in which the upper thread holding operation is finished and the clamp 13 holds the upper thread 3a.
[0042]
The operation timing and operation time of the wiper 12 in steps ST31 to ST34, the supply timing of the negative pressure to the negative pressure path 16, the operation timing of the clamping cylinder 18, the negative pressure supplied to the negative pressure path 16 The stop timing and the like are the initial settings in step ST10, for example, set by a timer, or set by a thread trimming program stored in the program storage area 21b based on input data. Further, the driving of the wiper 12 in step ST31 and the supply of the negative pressure in step ST32 may be started simultaneously, or the operation order may be reversed.
[0043]
Next, in step ST40, an upper and lower thread holding operation for cutting the thread 3 at the start of sewing is performed. In this vertical thread holding operation, the sewing machine is driven for one stitch in step ST41, the wiper 12 is driven in step ST42, and negative pressure is supplied to the negative pressure path 16 of the clamp 13 of the thread holding means 9 in step ST43. In step ST44, the clamping cylinder 18 of the yarn holding means 9 is positively driven, in step ST45, the clamping cylinder 18 of the yarn holding means 9 is reversely driven, and in step ST46, the negative pressure path 16 of the clamp 13 of the yarn holding means 9 is driven. When the supply of the upper and lower threads is completed, the process proceeds to the next step ST50.
[0044]
The upper and lower thread holding operation will be further described.
[0045]
The driving of the sewing machine 8 for only one stitch in the step ST41 is based on a sewing machine motor (not shown) based on a control command sent from the control means 11 with the clamp 13 shown in FIG. 6 holding the upper thread 3a. And the needle 6 is reciprocated once in the vertical direction once.
[0046]
When the needle 6 reciprocates up and down only once, the tip of the needle 6 passes through the fabric 1 and is positioned below the needle plate 7 due to the lowering of the needle 6. Next, when the needle 6 moves up, the thread end of the lower thread 3b positioned below the needle plate 7 is entangled with the upper thread 3a hung on the needle 6. Next, when the needle 6 rises and returns to the original position and stops, the thread end of the lower thread 3b is entangled with the upper thread and pulled up above the fabric 1. As a result, the lower thread 3b is located above the needle plate 7. Located in. FIG. 7 shows a state where the sewing machine 8 is driven by one stitch and the lower thread 3b is positioned above the needle plate 7.
[0047]
The drive of the wiper 12 in the step ST42 captures the lower thread 3b located above the needle plate 7, and the operation is the same as the drive of the wiper 12 in the step ST31. Therefore, the detailed description about the drive of the wiper 11 in step ST42 is abbreviate | omitted. FIG. 8 shows a state in which the hook 12a of the wiper 12 has captured the lower thread 3b.
[0048]
The supply of the negative pressure to the negative pressure path 16 of the clamp 13 of the yarn holding means 9 in step ST43 is the same as the supply of the negative pressure to the negative pressure path 16 of the clamp 13 of the thread holding means 9 in step ST32. . Therefore, the detailed description about supply of the negative pressure to the negative pressure path 16 of the clamp 13 of the yarn holding means 9 in step ST43 is omitted.
[0049]
The positive drive of the clamping cylinder 18 of the yarn holding means 9 in the step ST44 is based on the control command sent from the control means 11 so that the output shaft 18a of the clamping cylinder 18 located at the forward end is directed toward the backward end. This is done by driving.
[0050]
When the clamping cylinder 18 is positively driven, Progress The output shaft 18a of the clamping cylinder 18 positioned at the end contracts to reach the retracted end, and the ball body 17 attached to the tip of the output shaft 18a is sucked while the tip of the output shaft 18a is positioned at the retracted end. Separate from the hole 15. At this time, since the negative pressure is supplied to the negative pressure path 16 in step ST43, the yarn end of the upper thread 3a already held by the clamp 13 is held in the negative pressure path 16. Can do. Further, when the ball body 17 attached to the tip of the output shaft 18a of the clamping cylinder 18 is separated from the suction hole 15, a negative pressure is applied to the suction hole 15, and the suction hole is hooked by the hook 12a of the wiper 12 in step ST42. The yarn end of the lower yarn 3 b located near 15 passes through the suction hole 15 and is sucked into the negative pressure path 16. That is, both the yarn ends of the upper thread 3 a and the lower thread 3 b can be sucked into the negative pressure path 16.
[0051]
The reverse driving of the clamping cylinder 18 of the yarn holding means 9 in the step ST45 is the same as the reverse driving of the clamping cylinder 18 of the yarn holding means 9 in the step ST33. Therefore, detailed description of the reverse drive of the clamping cylinder 18 of the yarn holding means 9 in step ST45 is omitted.
[0052]
Then, the ball body 17 attached to the tip of the output shaft 18a of the clamping cylinder 18 by the reverse drive of the clamping cylinder 18 of the yarn holding means 9 in step ST45 is sucked through the upper yarn 3a and the lower yarn 3b. As a result, the yarn ends of the upper and lower yarns 3 can be held by the clamp 13. FIG. 9 shows a state in which the clamp 13 holds the upper and lower threads 3 together.
[0053]
In step ST46, the supply of negative pressure to the negative pressure path 16 of the clamp 13 of the yarn holding means 9 is stopped in step ST34. Is the same. Therefore, detailed description of stopping the supply of negative pressure to the negative pressure path 16 of the clamp 13 of the yarn holding means 9 in step ST46 is omitted.
[0054]
Note that the operation timing and operation time of the wiper 12 in steps ST41 to ST46, the supply timing of negative pressure to the negative pressure path 16, the operation timing of forward and reverse operations of the clamping cylinder 18, the negative pressure path The stop timing of the negative pressure supplied to 16 is set in the initial setting in step ST10, for example, by a timer or by a thread trimming program stored in the program storage area 21b based on input data.
[0055]
Next, sewing is started in step ST50. In this sewing operation, a sewing machine motor (not shown) is operated on the basis of a control command sent from the control means 11 with the thread ends of the upper thread 3a and the lower thread 3b held by the clamp 13 of the thread holding means 9. It starts by driving and proceeds to the next step ST60. At this time, the interval L of the first stitch 2 when the sewing operation as the feed pitch of the first first fabric 1 at the start of sewing after the clamp 13 of the yarn holding means 9 holds the yarn 3 is started. It can be made smaller than the interval P of the seam 2.
[0056]
The interval L between the stitches 2 of the first stitch at the start of sewing is an initial setting in step ST10, for example, set by a pitch selection dial or stored in the program storage area 21b based on input data. Set by the cutting program.
[0057]
Next, in step ST60, the thread end of the thread 3 at the start of sewing is cut. When the sewing operation proceeds and the fabric 1 is fed by 3 to 4 stitches, the knife 19 of the sewing product presser 10 positioned on the fabric 1 is clamped by the thread holding means 9. This is done automatically by cutting the yarn 3 held at 13 above the fabric 1.
[0058]
That is, as the needle 6 of the sewing machine 5 moves up and down and the fabric 1 advances, the thread end is held at the clamp 13 of the thread holding means 9 as shown by the arrow B in FIG. 3 gradually approaches the knife 18 of the sewing material presser 10, the thread 3 at the start of sewing comes into contact with the knife 18 at a position where the fabric 1 has advanced, for example, about 3 to 4 stitches, and the thread 3 is cut at the start of sewing. As a result, the thread end of the thread 3 at the start of sewing is separated from the fabric 1 and remains on the clamp 13 of the thread holding means 9, and the thread trimming operation of the thread 3 at the start of sewing is completed. FIG. 11 shows a sewing shape after the thread trimming operation of the thread 3 at the start of sewing is completed.
[0059]
After the thread 3 is cut at the start of sewing, the thread 3 that is not sewn into the cloth 1 and is separated from the cloth 1 and remains on the clamp 13 becomes thread waste, and until the next upper thread holding operation is started. In accordance with a control command sent from the control means 11 at a desired timing, the clamping cylinder 18 is moved forward to be removed from the clamp 13.
[0060]
In step ST70, as is well known, when all desired seams 2 are formed on the fabric 1, the sewing machine motor (not shown) is stopped, and the process proceeds to the next step ST80.
[0061]
Next, in step ST80, as is well known, the upper and lower threads 3 are cut under the needle plate 7, and the process proceeds to the next step ST80.
[0062]
In step ST80, when cutting the upper and lower threads 3 under the needle plate 7, as shown in FIG. 12, the fixed blade 32 of the thread cutting device 30 having a known movable blade 31 and fixed blade 32 is used. The lower thread after cutting under the needle plate 7 as the position where the arrangement position is separated in the direction orthogonal to the movement path NL of the needle 6 shown by the double-pointed arrow in FIG. The thread end 3b is clamped at a position indicated by C in FIG. 12, which is separated in a direction orthogonal to the movement path NL of the needle 6, and is disposed below the needle plate 7 and attached to the shuttle 33. It is preferable that the lower thread 3b wound around the lower thread bobbin 34 is pulled out from the lower thread bobbin 34 for a long time when the lower thread 3b is retained by the thread retaining means 9. The movable blade 31 is configured to advance and retreat between a standby position indicated by a solid line in FIG. 12 and a cutting position indicated by a broken line in FIG. 12, and the upper and lower threads 3 after sewing has been completed. , And is cut at a position indicated by a symbol D in FIG.
[0063]
Next, in step ST90, it is determined whether or not new sewing is performed. If the determination in step ST90 is YES (following new sewing is performed), the process proceeds to the next step ST91, and in step ST91. Then, it is determined whether or not a new initial setting is necessary. If the determination in step ST91 is YES (initial setting is required), for example, if the type of the fabric 1 is changed, the process returns to step ST10, and step ST91. If the determination is NO (initial setting is not required), for example, if the same sewing is continued, the process returns to step ST20.
[0064]
If the determination in step ST90 is NO (no new sewing is performed subsequently), for example, when the sewing machine 8 is stopped for a long time such as when the operator finishes the day's work or the operator rests, the power is turned off. And finish.
[0065]
Thus, according to the thread trimming device 5 of the present embodiment, as shown in FIG. 11, the thread ends of the upper thread 3 a and the lower thread 3 b at the start of sewing are reliably and easily cut from the fabric 1. Can be reliably shortened, so that it is possible to reliably prevent the occurrence of the bird's nest 4 in which both the upper thread 3a and the lower thread 3b at the start of sewing are entangled with the seam 2 at the start of sewing. Quality can be improved reliably. Further, the feed pitch of the first stitch 1 after the yarn holding means 9 holds the upper yarn 3a and the lower yarn 3b, that is, the interval L between the first stitches 2 formed on the fabric 1 is the same as that of the normal stitch 2. Since it can be made smaller than the space | interval P, an external appearance quality improves more and a sewing product quality can be improved more.
[0066]
FIGS. 13 and 14 show another example of the embodiment of the thread trimming device of the sewing machine according to the present invention. The thread trimming device 5a of the present embodiment is mechanically operated without using negative pressure. The thread holding means 9a for holding the thread 3 includes a thread grip 40 for gripping the thread 3 and a thread presser 41 for holding the thread 3 on the thread grip 40. Have.
[0067]
A base end portion of the thread clamp 40 is pivotally supported by a support shaft 42 and is connected to one end of a thread clamp drive link mechanism 44 constituted by a plurality of link plates. The thread clamp drive link mechanism 44 can be driven by a thread clamp drive actuator 45 such as a solenoid. That is, the thread clamp 40 is driven to advance and retreat a plunger (not shown) of the thread clamp drive actuator 45 so that the thread clamp 40 passes under the needle 6 and is in the standby position. And the operation position can be reciprocated.
[0068]
The thread retainer 41 is formed of an elastic body such as a leaf spring, and its tip is disposed so as to abut one surface (upper surface) of the thread clamp 40 with a desired urging force. The proximal end of the thread retainer 41 is attached to the distal end of a thread retainer holder 46 whose proximal end is supported by the support shaft 42. Furthermore, the support shaft 42 is connected to one end of a thread presser drive link mechanism 48 constituted by a plurality of link plates 47. The thread presser drive link mechanism 48 can be driven by a thread presser drive actuator 49 such as a solenoid. That is, the thread retainer 41 can be brought into and out of contact with the thread clamp 40 by driving the plunger (not shown) of the thread retainer driving actuator 49 so as to advance and retreat. Other configurations are the same as those of the thread trimming device 5 of the above-described embodiment.
[0069]
According to the yarn cutting device 5 of the present embodiment having such a configuration, the yarn 3 can be held by a mechanical operation without using a negative pressure, and therefore the yarn holding means 9a holds the yarn 3. Noise can be reduced.
[0070]
The present invention is not limited to the embodiments described above, and can be changed as necessary.
[0071]
【The invention's effect】
As described above, according to the thread trimming method and apparatus of the sewing machine of the present invention, the upper and lower threads at the start of sewing are held by the thread holding means, and the upper and lower threads held by the thread holding means are cut by the sewing material presser. This means that the thread at the start of sewing can be cut, so that it is possible to reliably prevent the formation of bird's nest by the thread at the start of sewing and to improve the quality of the sewing product. There is an effect.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a main part of an example of an embodiment of a thread trimming device of a sewing machine according to the present invention to which a thread trimming method of the sewing machine according to the present invention is applied.
FIG. 2 is a plan view of the sewing product presser shown in FIG.
FIG. 3 is a block diagram of the control means of FIG.
FIG. 4 is a flowchart showing an example of an embodiment of a thread cutting method for a sewing machine according to the present invention.
FIG. 5 is an explanatory view showing a state in which sewing in the operating state of the thread trimming device of the sewing machine in FIG. 1 is finished and the upper and lower threads are cut under the needle plate.
6 is an explanatory view showing a state in which the clamp in the middle of the operation following FIG. 5 of the operation state of the thread trimming device of the sewing machine of FIG. 1 holds the upper thread.
7 is an explanatory view showing a state in which the sewing machine in the middle of the operation state following FIG. 6 of the operating state of the thread trimming device of FIG. 1 is driven by one stitch and the lower thread is positioned above the needle plate.
8 is an explanatory diagram showing a state where the hook of the wiper in the middle of the operation state of the thread trimming device of the sewing machine of FIG.
FIG. 9 is an explanatory diagram showing a state in which the clamp in the middle of the operation following the state of FIG. 8 of the operation state of the thread trimming device of the sewing machine of FIG. 1 holds the upper and lower threads together.
FIG. 10 is an explanatory diagram showing a state immediately before the thread is cut at the start of sewing accompanying the sewing operation halfway through the operation state of the thread trimming device of the sewing machine of FIG. 1;
FIG. 11 is an explanatory view showing, in an enlarged manner, a sewing state in which a thread is cut at the start of sewing by the thread trimming device of the sewing machine in FIG. 1;
12 is an explanatory diagram showing an example of a preferable state when cutting the upper and lower threads under the needle plate in the thread trimming device of the sewing machine of FIG. 1;
FIG. 13 is a perspective view showing a main part of another example of the embodiment of the thread trimming device of the sewing machine according to the present invention to which the thread trimming method of the sewing machine according to the present invention is applied.
FIG. 14 is a side view of FIG.
FIG. 15 is an explanatory view showing an enlarged sewing state with a bird's nest generated by upper and lower threads at the start of conventional sewing
FIG. 16 is an explanatory view showing an enlarged sewing state with a bird's nest generated by a lower thread at the start of conventional sewing
[Explanation of symbols]
1 Fabric (as sewing)
2 seams
3 Yarn
3a Upper thread
3b Lower thread
5, 5a Thread trimming device for sewing machine
6 needles
8 Sewing machine
9, 9a Thread holding means
10 Sewing material presser
11 Control means
19 Female (for sewing presser foot)

Claims (3)

  Before the start of sewing, the upper thread positioned above the needle plate is captured and the end of the upper thread is held. In this state, the sewing machine is driven by one stitch to position the lower thread end above the needle plate. The lower thread positioned above the needle plate is captured and held with the upper thread end already holding the thread end. In this state, sewing is started and the upper thread and the upper thread and A thread trimming method for a sewing machine, wherein a thread end of a thread at the start of sewing of a lower thread is cut. Sewing presser with a knife to cut the thread;
Thread holding means capable of holding a thread located above the needle plate;
Before starting the sewing, the thread holding means is driven to catch the upper thread located above the needle plate and the thread end is held by the thread holding means. In this state, the sewing machine is driven by one stitch. The thread end of the thread is positioned above the needle plate, and after the driving of the sewing machine for one stitch is finished, the thread holding means is driven to catch the lower thread positioned above the needle plate and the thread end is Control means for driving the thread holding means and the sewing machine so as to be held by the thread holding means together with the yarn end of the upper thread already held;
A thread trimming device for a sewing machine comprising: The said control means controls the feed pitch of the sewing product of the 1st 1st stitch after the said thread | yarn holding means hold | maintains an upper thread and a lower thread smaller than the space | interval of a normal stitch. Sewing machine thread trimming device.

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