JPH0733743Y2 - Sewing machine with automatic thread trimmer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a sewing machine having an automatic thread cutting device in which thread cutting is performed by pressing a thread cutting switch.

[Prior Art] In a conventional household sewing machine, a thread trimming operation member and a reverse operation member for performing reverse feed sewing are arranged close to the machine frame of the sewing machine, and the reverse operation member is operated at the end of sewing or the like. Then, tie-off sewing was performed, and then thread trimming was performed to complete the sewing work.

[Problems to be solved by the invention] In such a sewing machine, since both operation members are close to each other, when the thread cutting operation member is erroneously touched when operating the reverse operation member, the sewing machine is driven. As the thread trimming device operates, the needles that move up and down engage with the thread trimming member that operates, causing breakage of the needle or damage to the blade portion of the thread trimming member, and stitches being interrupted midway. There were drawbacks such as deterioration of the quality of sewn products. Also, when the thread cutting operation member is operated while operating the operation member such as the controller for driving the sewing machine, the needle breakage or the thread cutting blade portion is similarly damaged.

[Means for Solving the Problem] Thread cutting means for cutting a sewing thread connected to a seam under the cloth, operating means for electrically operating the thread cutting means, and moving the cloth in the forward or reverse direction. Feed dog,
Reverse operation means for reversing the feed direction by the feed dog by operation provided on the machine frame on the front side of the sewing machine, and operation provided on the machine frame on the machine front side close to the reverse operation means above to operate the operation means. To generate a signal for operating the sewing machine motor, operating means for operating the sewing machine motor, rotation detecting means for detecting rotation of the sewing machine motor, and the operation for operating the thread cutting operation means. And a control means for inhibiting the operation of the operating means when the means is operated or when the detecting means detects the rotation of the sewing machine motor.

[Operation] According to the present invention, since the thread trimming switch is arranged above the operation portion of the reverse lever, when performing reverse stitching at the end of sewing, the thread trimming can be smoothly performed without greatly moving the hand. Even if the thread trimming switch is accidentally touched during operation of the feed dial, etc., the controller sends the thread trimming solenoid to the thread trimming solenoid when the motor is rotating, the bobbin is rotating, and the controller switch is on. Since the signal of is off, the thread trimming solenoid is not driven and thread trimming is not performed.

[Embodiment] Referring to FIG. 1, in a sewing machine having an automatic thread trimmer according to an embodiment of the present invention, a sewing machine arm 2 on a bed 1 is provided.
A needle bar 4 to which a needle 3 is attached is provided on the head of the, and a presser bar holding thread guide 5 is provided on the needle bar 4. Further, a thread tension device 6 is provided on a side portion of the presser bar holding thread guide 5, a balance 7 is mounted on an upper portion of the presser bar holding thread guide 5, and a thread guide 8 is provided on a side portion thereof. Further, a reverse lever 9 for reverse stitching is attached to the front surface of the vertical body portion of the sewing machine arm 2 in the vicinity of the bed 1, and further, a thread trimming switch 10 is attached to an upper portion of the reverse lever 9, and further, the thread trimming switch 10 A feed dial 11 capable of adjusting the feed pitch of the cloth feed movement of the feed dog is mounted on the upper part of the. Belt cover on the side of the vertical body of the sewing machine arm 2.
12 is mounted, and a flywheel 13 is projected from the belt cover 12.

Referring to FIG. 2 and FIG. 3, a picture of scissors is drawn on the operating portion 14 of the thread trimming switch 10, and this operating portion 14 serves as the operating axes of the two switches 16a and 16b mounted on the thread trimming board 15. Engaged. The thread trimming board 15 is fixed to the thread trimming board case 17 with a screw 18, and the thread trimming board case 17 is screwed.
It is fixed to the sewing machine arm 2 by 19. The operation surface of the operation portion 14 of the thread trimming switch 10 is formed substantially flush with the front surface of the vertical trunk portion of the sewing machine arm 2.

In the sewing machine of this embodiment configured as described above, since reverse stitching is always performed at the end of sewing, the thread trimming switch 10 is provided above the reverse lever 9 so that the thread trimming switch does not have to be largely moved after reverse stitching. You can press 10, and thread cutting can be performed smoothly.

Referring to FIG. 4, in the control circuit of the sewing machine having the automatic thread trimming device according to the first embodiment of the present invention, the thread trimming switch 10 is connected to the input side of the control device 20, and the input side of the control device 20 is connected. A speed controller 21, a spindle detection device 22, a bobbin winding switch 23 (a switch for winding a bobbin on a bobbin), and a motor rotation detector 24 are connected. And
A stop solenoid 26 (which stops the main shaft of the sewing machine by the operation of the solenoid) is connected to the output side of the control device 20 via a stop solenoid drive device 25, and a thread cutting solenoid 28 is connected via a thread cutting solenoid drive device 27. Further, the motor 30 is connected via the motor drive device 29.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG. First, when the thread trimming switch 10 is turned on, the control device 20 confirms this, and then determines whether the thread winding switch 23 is off (step 1). When the control device 20 confirms that the bobbin winder switch 23 is off, the control device 20 further determines whether the speed controller 21 is off (step 2). If this off confirmation is made, the control device 20 further determines that the motor rotation detector is on. It is determined whether the output of 24 is 0 (step 3). When the control device 20 confirms 0, it is judged whether the thread trimming switch 10 is continuously turned on (step 4). If it is continuously turned on, the control device 20 sends a signal to the thread trimming solenoid drive device 27. And the thread cutting solenoid 28 is driven to perform the thread cutting operation. If the thread trimming switch 10 is off in step 4, the thread trimming switch 10 is turned on and the thread trimming operation is performed again through steps 1 to 4. In step 1, if the thread winding switch 23 is turned on, the thread winding operation is in progress (step 5). Therefore, after the thread winding operation is completed (step 6), the thread cutting switch is turned on and the steps 1 to 4 are performed. After that, the thread cutting operation is performed. Further, in steps 2 and 3, if the speed controller 21 and the motor rotation detector 24 are on and the output is not 0, no output is output to the thread cutting solenoid 28 until the speed is turned off and 0. No action is taken.

In this embodiment, as described above, the control device 20 confirms whether the output of the bobbin switch 23 and the speed controller 21 are both off, and the output of the motor rotation detector 24 is 0, and outputs of those devices are checked. If is on and not 0, thread trimmer solenoid drive 27 until off and 0
The signal to is stopped. Therefore, by mistake, the thread trimming switch
Even if you press 10, the thread trimming operation is not performed while the sewing machine is rotating.

In the above description, the operation unit of the thread trimming switch 10
Since the operation surface of 14 is formed substantially on the same surface as the front surface of the vertical trunk portion of the sewing machine arm 2, it is easy to operate without touching the operation surface of the operation portion 14 when operating the feed dial 11.

Further, since the operating portion 14 is adapted to be engaged with the operating shafts of the two switches 16a and 16b, either one of them is inevitable depending on the difference in the pushing method of the operating portion 14 (the difference when pushing from the right angle or the tilt direction). One switch can be turned on and thread trimming switch 10
The operability is high for the operator as compared with the case where only one switch is used.

[Effect of the Invention] As described above, according to the present invention, the thread cutting operation is not performed even if the thread cutting operation means is operated by mistake while the sewing machine is being driven. Therefore, the needle is broken or the thread cutting mechanism is damaged. It is possible to prevent accidents such as the above, and it is possible to reliably and continuously form the seams, and it is possible to improve the quality of the sewn product. Further, since the reverse operating means for the stop stitching performed immediately before the end of sewing and the thread trimming operating means for thread trimming performed immediately after the end of sewing are arranged close to each other above, the operation can be continuously performed with one hand. Therefore, the effect of improving the working efficiency is obtained, and since the operation of the actuating means is prohibited even if the operating means is operated by mistake when the reverse operating means is operated, the effect of preventing malfunction can be obtained.

[Brief description of drawings]

1 is a front view of a sewing machine having an automatic thread trimming device according to an embodiment of the present invention, FIG. 2 is a side sectional view of the thread trimming switch of FIG. 1, and FIG. 3 is a thread trimming switch of FIG. FIG. 4 is an exploded perspective view, FIG. 4 is a block diagram of a control circuit of a sewing machine having the automatic thread trimming device of FIG. 1, and FIG. 5 is a flow chart for explaining the operation of the control circuit of FIG. 10 ...... Thread trimming switch, 20 ...... Control device, 21 ...... Speed controller, 22 ...... Spindle detection device, 23 ...... Thread winding switch, 24 ...... Motor rotation detector, 25 ...... Stop solenoid drive device, 26 ... … Stop solenoid, 27 …… Thread trimming solenoid drive, 28 …… Thread trimming solenoid, 29 …… Motor drive, 30 …… Motor.

Claims (1)

[Scope of utility model registration request] 1. A thread cutting means for cutting a sewing thread connected to a seam under a cloth, an operating means for electrically operating the thread cutting means, and a feed dog for moving the cloth in a forward or reverse direction. Reverse operation means for reversing the feed direction by the feed dog by operation provided on the machine frame on the front side of the sewing machine, and operation means for operating the operation means provided on the machine frame on the machine front side close to the reverse operation means above. To generate a signal for operating the sewing machine motor, operating means for operating the sewing machine motor, rotation detecting means for detecting rotation of the sewing machine motor, and the operation for operating the thread cutting operation means. Control means for prohibiting the operation of the operating means when the means is operated or when the detecting means detects the rotation of the sewing machine motor. That sewing machine.