JPS6025151B2 - Sewing machine needle thread supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a needle thread supply device for a sewing machine that allows needle thread of a required length to be fed out from a needle thread supply source in advance for each stitch formation, and particularly to The purpose is to improve the quality of the product by making the amount accurate and making the thread kneading constant for each seam.

Embodiments of the present invention will be described below with reference to the drawings.

About the configuration The sewing machine has a main shaft (
(not shown) is provided inside.

A needle bar 2 fixes a needle 3 having a needle thread T and moves up and down in conjunction with the main shaft. The thread take-up 4 supports the needle thread T between the bobbin 5 as a needle thread supply source and the needle 3, and moves around the main shaft to tension and relax the needle thread T, and moves the needle thread top dead center to 000 as shown in FIG. It reciprocates between two positions according to the balance curve. The shafts 6 and 7 are spaced apart from each other on one side and the other across the needle thread path between the thread take-up 4 and the spool 5, and are supported on the machine frame so as to be rotatable about mutually parallel axes.

A first roller 8 and a third roller 9 having the same diameter are fixed to one end corresponding to each of the shafts 6 and 7, and sprockets 10 and 11 having the same diameter are fixed to the other end. The motor 12 has a sprocket 13 on its output shaft and always rotates counterclockwise in FIG. across. The oscillating body 15 is supported on the machine frame so as to be able to oscillate about an axis 16 parallel to the axis 7 at the intermediate portion on the axis 7 side of the needle thread path, and a coil spring 3 stretched between the oscillating body 15 and the iso frame.
4, it always receives rotational force in the clockwise direction. A second roller 17 corresponding to the rollers 8 and 9 is rotatably supported at one end of this rocking body 15, and a needle thread T is attached to a receiving portion 18 fixedly arranged on the shaft 6 side of the needle thread path at the end of the rocker. A presser portion 19 is provided which faces each other with the two sides in between. The receiving portion 18 and the holding portion 19 constitute a holding means. The electromagnetic solenoid 20 has an outer frame rotatably supported on the machine frame about a shaft 21 parallel to the shaft 16, and also rotatably connects the protruding end of the armature 22 to the rocking body 15. Note that 23, 24, and 25 are thread guides, and there is always a needle thread T between thread guides 23 and 24.
The lever 4 acts to pull upward and bend the lever.
A thread take-up spring 26 is arranged which has an elastic force weaker than the maximum tension of the needle thread T when the needle thread is tensioned by the operation of the thread guide 2.
A base tension 27 is disposed between the needle thread T and the bobbin spool 5, which always provides a weak constant resistance to the needle thread T.

Next, the electric circuit will be explained.

The position detection device 28 is arranged in relation to the main shaft, and detects the rotation angle of the main shaft (115° in the embodiment) at which the thread take-up descends and the needle thread T begins to loosen after the stitch knotting is completed, and generates a position signal. do.

The reference timer 29 always generates pulses of a constant frequency. Counter 30 counts pulses from reference timer 29 and is reset by the output of position detection device 28. The setting device 31 is composed of sensors corresponding to cloth thickness, needle swing, cloth feed pitch, etc., and uses a digital code to send a setting signal corresponding to the length of time proportional to the length of needle thread T required for forming one stitch. Occur. Comparison circuit 32 compares the outputs of counter 30 and setting device 31, and generates a match signal when both match. The flip-flop FF is of the RS type, and is set by the position signal from the position detection device 28 to output a high level (H) signal from the Q terminal, and lowers the Q terminal output in relation to the match signal from the comparator circuit 32. Inverted to level (L). The excitation circuit 33 receives the input of the sun and turns the solenoid 2 on.
0 is energized, and upon receiving the L input, the solenoid 20 is closed so as to be deenergized. Regarding the operation, as shown in FIG. 4a, the oscillating body 15 is rotated clockwise by the elastic restoring force of the coil spring 34, so that the needle thread T passes between the presser part 19 and the receiving part 18. The second roller 17 is in pressure contact with the third roller 9 while being impossibly supported.

When the sewing machine is turned on from this state, the motor 12 starts and the sprockets IQ and 1 are connected via the timing belt 14.
1 and 13 rotate counterclockwise, the first and third rollers 8 and 9 rotate in the counterclockwise direction, and the second roller 17 rotates clockwise at the same circumferential speed. Further, the reference timer 29 operates simultaneously with the motor 12 and outputs pulses of a constant frequency. Next, when sewing conditions such as cloth thickness, pitch, stitch width, etc. are input to the setting device 31, a setting signal having a value corresponding to the setting conditions is outputted from the setting device 31. When the sewing machine 1 is driven, the thread take-up 4 descends from the top dead center and the needle thread T on the side of the take-up 4 relative to the holding means 18 and 19 begins to loosen.
A position signal is generated from the position detection device 28 and sent to the counter 30.
and set the FF. As a result, the excitation circuit 33 is opened and the solenoid 20 is energized, and as shown in FIG.
As shown in , since the oscillator 15 is rotated in the direction of the rebound indicator, the presser foot 19 separates from the receiving portion 18 and releases the needle thread T, and at the same time, the second roller 17 separates from the third roller 9 and moves toward the first roller. The needle thread T is brought into pressure contact with the roller 8, and the needle thread T is let out from the bobbin 5 by the cooperation of both rollers 8 and 17. At the same time as the solenoid 20 is energized, the pulses output from the reference timer 29 are counted by the counter 301, and the counted value is compared with the setting value of the setting device 31 in the comparison circuit 32. When both outputs match, the pulse from the comparison circuit 32 is The match signal resets the FF, closes the excitation circuit 33, and demagnetizes the solenoid 20.

As a result, the oscillating body 15 is returned to the state shown in FIG. is pulled up, and at the end of the tension of the needle thread T by the thread take-up 4, the stitch of a predetermined thread tension is knotted.As the thread take-up 4 descends from the top dead center, The needle thread warp gradually becomes shorter, but until the second roller comes into pressure contact with the first roller 8, a length of the needle thread T corresponding to the shortening of the needle thread path due to the lowering of the thread take-up lever 4 is taken up. As the spring 26 returns upward due to the elastic force, it is deeply bent upward and taken up as shown in FIG. 4b, so that the balance 4
When the rollers 7 and 8 are in pressure contact with each other as shown in FIG. 4b, the slack of the needle thread T due to the lowering of the needle thread T does not occur closer to the bobbin 5 than the rollers 7 and 8.

Therefore, the length of the needle thread T that is fed out to the thread take-up 4 by both rollers 8 and 17 is always accurately fed out from the bobbin 5. In addition, since the second roller 7 rotates at the same speed as the first roller 8 in conjunction with the third roller 9 even during the period when the needle thread T is not being fed out, the second roller 7 is in pressure contact with the first roller 8. No shock occurs when

As described above, the present invention includes a first roller that is close to the needle thread path between the thread take-up and the needle thread supply source and is rotatable around a fixed rut line, and a fixed roller that is parallel to the rotation axis of the first roller. The oscillator, which can pivot about its axis, and the first roller are located on opposite sides of the needle thread path, and the outer periphery faces the outer periphery of the first roller, and is rotatable at the free end of the oscillator. A supported second roller, a motor that always rotates at a constant speed in conjunction with the first roller or the second roller, and an electric actuator that acts electrically to move the second roller relative to the first roller to swing the swinging body. In a needle thread supply device equipped with an actuating means for forming one stitch, the actuating means is operated for a time proportional to the length of the needle thread required to form one stitch in response to different sewing conditions, and the two rollers are brought together. The needle thread of the required length is fed out from the spool to the thread take-up for each stitch formation.In addition to the motor as the drive source for the roller, it is sufficient to use an inexpensive motor as long as it rotates at a constant cycle. In addition to making the device inexpensive, the rollers that are linked to the outer roller always rotate at a constant speed, and the time that the first roller and second roller are connected is directly proportional to the length of the needle thread that is fed out. Therefore, there are effects such as the ability to easily and accurately control the length of the needle thread.

Note that in this embodiment, the holding part 19 facing the receiving part 18 is formed integrally with the swinging body 15, but the holding part formed separately from the swinging body 15 is provided separately from the solenoid 20 in this embodiment. It may be configured to operate at the same timing as in the example. Further, in this embodiment, a third roller 9 is provided,
Although the rollers 8, 9, and 17 are always rotated at the same circumferential speed by interlocking the second roller 17 with the third roller 9 when the needle thread T is not being fed out, the rollers 8, 9, and 17 may be rotated at the same circumferential speed. good.

Furthermore, in this embodiment, basic data regarding the length of needle thread required to form one stitch is set using a sensor, but data obtained by detecting the setting position of the needle swing adjustment means or feed adjustment means or the needle swing mechanism or From the data that detects the momentum of the cloth feeding mechanism, pre-memorized yarn amount data may be read from the storage device, and this data may be used as the basic data for the unreeling length.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the needle thread supply device, FIG. 2 is a block diagram of the electric circuit, FIG. 3 is a time chart, and FIGS. 4a and 4b are action explanatory views. 4... Balance, 8... First roller, 12
．．・・・． ... Motor, 15 ... Rocking body, 17 ...
・Second roller, 18, 19... Holding means, 20
...Actuation means, 28...Position detection device, 31...Setting device, 30, 32, 33, FF
...control circuit. Sait tzu sai 2 sai 3 sai 4 sai buddha) sai 4 sakume

Claims (1)

[Claims] 1. A first roller that is close to the needle thread path between the thread take-up and the needle thread supply source and is rotatable about a fixed axis; and a first roller that is swingable about a fixed axis that is parallel to the rotating axis of the first roller. a second roller located on the opposite side of the needle thread path from the first roller and rotatably supported at the free end of the swinging body with its outer periphery facing the outer periphery of the first roller; A motor that is linked to the first roller or the second roller and always rotates at a constant speed in one direction, and is placed on the needle thread path between both rollers and the needle thread supply source,
a holding means that acts on the needle thread so that the needle thread cannot pass through the needle thread due to an action and allows the needle thread to pass through the needle thread when the needle thread does not pass; An actuating means that operates electrically so that the holding means is inactive when both rollers are joined and the holding means is activated when both rollers are separated, and the length of needle thread required to form one stitch corresponding to different sewing conditions. A setting device that can generate a setting signal that corresponds to a time that is directly proportional to the time, a position detection device that generates a position signal by detecting a specific angle of the main shaft that corresponds to the time when the needle thread is relaxed due to the operation of the thread take-up, and a position detection device that generates a position signal that a control circuit for causing the actuating means to separate the rollers from each other and to join the rollers in relation to the position signal from its occurrence until a time corresponding to the set signal has elapsed; .