JPS6157038B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Technical Field] The present invention provides a needle thread supply device for a sewing machine that feeds a needle thread of a length necessary for forming one stitch from a bobbin winder to a thread take-up every time one stitch is formed. It is related to.

[Prior art]

FIG. 1 is a perspective view of the main parts of a needle thread feeding device of a sewing machine equipped with a conventional automatic thread tension device. A needle 2 through which the thread T is threaded is fixed at the lower end, a needle bar 3 that moves up and down in conjunction with the main shaft, and a needle thread T between the needle 2 and a bobbin spool 4 as a needle thread supply source are supported. It is equipped with a take-up lever 5 that reciprocates between two positions in conjunction with the main shaft so that the needle thread T is tensioned and relaxed, and the positional relationship between the needle bar 3 and take-up 5 with respect to the rotation angle of the main shaft is set. has been done.

The first holding means 6 and the second holding means 7 are attached to the balance 5.
The first solenoid 8 and the second solenoid 9 are arranged separately on the needle thread path between the bobbin spool 4 and the bobbin thread take-up 4 in the upper thread supply direction from the bobbin spool 4 to the thread take-up take-up 5. It consists of a pair of holding plates 10 and 11, which clamp the upper thread T so that it cannot move, and are released so that the upper thread T can move when it is not energized.

The auxiliary thread take-up 12 is linked to an eccentric cam 13 that rotates in conjunction with the main shaft, and can swing a certain amount around a shaft 14, and its free end is connected to the upper thread path between the two holding means 6 and 7. When the needle 2 is positioned below the bed surface, the upper thread path between the holding means 6 and 7 is increased, and the upper thread T is tensioned by the thread take-up 5. Sometimes this is associated with the movement of the needle 2 and the thread take-up 5 in such a way that the required amount of thread is supplied per stitch.

Further, the rotating body 15 is arranged between the holding means 6 and 7 so that it can rotate in proportion to the distance traveled when the needle thread T is moved along its path.

When sewing with a sewing machine, the required amount of needle thread must be supplied correctly for each stitch depending on the sewing pitch, fabric thickness, etc. However, with conventional needle thread supply devices, The rotating body 15
An encoder 16 and the like are attached coaxially with the sewing machine, but this has the disadvantage that it is too expensive to be used in the needle thread supply device of a sewing machine.

[Summary of the invention]

This invention was made to improve this drawback.The number of pulses corresponding to the required amount of thread for each stitch is stored in advance as a table in a storage device, and based on the required amount of thread, By reading out the number of pulses corresponding to the required amount of thread from the table and inputting it to the counter as the output of the first setting device, the sewing machine can efficiently supply the upper thread without using an encoder or the like. A needle thread supply device is provided.

[Embodiments of the invention]

FIG. 2 is a perspective view showing an upper thread supply device including an automatic thread tension device which is an embodiment of the present invention;
FIG. 3 is a motion diagram of the same, and FIG. 4 is a block diagram of the same signal system, and 1 to 16 are the same as the conventional device.

In the figure, reference numeral 17 denotes a main shaft of the sewing machine 1, and a disk 19 having slits 18 formed at equal intervals around the circumference is fixed to the main shaft 17. This disk 19
A sensor 20 for detecting the presence or absence of the slit 18 is disposed at a position where the slit 18 is sandwiched, and a spindle pulse generator 21 is constituted by this sensor 20 and the disk 19. One pulse is generated each time it is rotated by a certain angle.

The auxiliary thread take-up 12 is reciprocated in conjunction with the rotation of the main shaft 17, and the upper thread is paid out, as in the conventional case. This device is different from the conventional device in that an encoder, etc., which is attached coaxially with the rotating body 15 and used for detecting the amount of yarn in the conventional device, is not attached.

With this configuration, in order for the sewing machine 1 to operate and the upper thread T to be supplied, the auxiliary thread take-up 1 must be
2 is reciprocated and the upper thread is paid out. After the auxiliary take-up 12 begins to move forward, the number of pulses generated in the main shaft pulse generator 21 is counted, and the first solenoid 8 and the second solenoid are It is easy to understand by referring to the motion diagram shown in FIG.

Now, there is no problem if the payout curve 22 formed as the auxiliary balance moves is a straight line on the motion diagram, but as shown in Fig. 4, it is a curve that cannot be easily approximated by a formula. , the number of pulses and the yarn amount are not treated as having a directly proportional relationship.

Therefore, in the present invention, for example, in a sewing machine that uses the microcomputer 23 as a calculation system, the number of pulses corresponding to the thread amount is
The idea is to store it in advance as a table in a storage device.

Furthermore, regarding the cloth to be sewn,
Based on the required amount of thread determined from the sewing pitch and fabric thickness,
The number of pulses corresponding to this required yarn amount is read from the above table, and the value is set by the first setting device 2.
It is sufficient if it is used as the set input of the counter 25 as the output of the counter 25.

In this manner, during sewing, first, an output corresponding to the needle thread amount is set and inputted to the counter 25 from the first setting device 24.

When sewing machine 1 is started, balance 5
When the upper thread T, which is closer to the needle than the second holding means 7, is lowered from the top dead center, the counter 25 is reset by the fall of the signal from the spindle position detector 26, and the flip-flop FF 27 is reset. is cleared, the operating circuit 28 is closed,
The first solenoid 8 is demagnetized, the upper thread T is released from being held by the first holding means 6, the operating circuit 29 is opened, and the second solenoid 9 is energized.
The second holding means 7 holds the upper thread T so that it does not pass through.

Immediately after this, the auxiliary thread take-up 12 is moved forward about the shaft 14, and the upper thread T between the two holding members 6 and 7 is bent and its supply route is gradually increased, which corresponds to the increased route. The needle thread T having a length of

When the upper thread T is paid out in this manner, the pulses generated from the spindle pulse generator 21 are counted by the counter 25, and when the counted value by the counter 25 matches the output of the first setting device 24, the A coincidence signal is issued, which sets the FF 27 and inverts the Q terminal output from L to H, so the first solenoid 8 is energized and the first holding means 6 prevents the upper thread T from passing. being held,
Thereafter, the upper thread T is prevented from being fed out, and the second solenoid 9 is demagnetized and the second holding means 7 is released so that the upper thread T is passed through.

In this way, based on the required yarn amount, the number of pulses corresponding to this required yarn amount is read from the above table, and the value is set and inputted to the counter 25 as the output of the first setting device 24, and is input to the auxiliary balance 12. The number of pulses generated by the pulse generator 21 corresponding to the length of the needle thread to be fed out is inputted to the counter 25, and when matched with the number of pulses output from the first setting device 24, the number of pulses is generated. The needle thread is clamped and released at the timing shown in FIG. 3 by both holding devices 6 and 7, which act in response to the signal from the machine. Even if the type of thread or fabric changes, it can be reliably supplied.

[Effects of the Invention] As described above, the present invention includes the first holding means and the second holding means.
A holding means is used, and the timing at which the upper thread is pinched and released by the first holding means and the time at which the upper thread is pinched by the second holding means is determined in accordance with the predicted amount of needle thread to be fed out for each stitch when the needle thread is let out. By determining the release timing, the upper thread of the sewing machine can be reliably supplied without using an encoder or the like, and it can be carried out at low cost.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a needle thread supply device of a conventional sewing machine, FIG. 2 is a perspective view showing a needle thread supply device of a sewing machine to which an embodiment of the present invention is applied, and FIG. 3 is a motion diagram of the same. , FIG. 4 is a block diagram of the same signal system. In the figure, 6 is a first holding means, 7 is a second holding member, 12 is an auxiliary balance, 17 is a main shaft, 21 is a main shaft pulse generator, 23 is a microcomputer,
24 is a first setting device, 25 is a counter, and 26 is a spindle position detection device. Note that the same reference numerals in each figure represent the same or corresponding parts.

Claims (1)

[Claims] 1. A main shaft position detection device that detects the angular position of the main shaft of the sewing machine, a main shaft pulse generator that generates pulses in conjunction with the main shaft, an auxiliary thread take-up that unwinds the needle thread in synchronization with the rotation of the main shaft, and this auxiliary thread take-up. A calculation system includes a first setting device in which the number of pulses generated while the needle thread is being let out by a thread take-up and the amount of needle thread for each stitch are stored in advance as a table, and the sewing pitch of the fabric to be sewn. The number of pulses corresponding to the upper thread amount determined from the material thickness is read from the above table and set as the output of the first setting device. The number of pulses generated while being fed out is counted by the spindle position detection device and the spindle pulse generator, and when this number of pulses is matched with the set number of pulses, the number of pulses is The thread is held in place
An upper thread supply device for a sewing machine, characterized in that the upper thread holding means is released.