JPS6038150B2 - Sewing machine needle thread supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention uses two holding means that can release the needle thread, and a line drawing body that is arranged on the needle thread path between the two holding means and operates in synchronization with the thread take-up. , the holding means on the supply source side is opened and the holding means on the balance side is closed at a time other than the time when the needle thread is tensioned by the thread take-up, and the needle thread path between both holding means is increased, and the needle thread is drawn out from the supply source; In connection with the predetermined amount of needle thread being dispensed, the holding means on the supply source side is closed to prevent subsequent line drawing, and the holding means on the thread take-up side is opened to allow the fed-out needle thread to be moved to the next rise of the thread take-up. Regarding a needle thread supply device of the type that actively draws out needle thread of the required length from a supply source for each stitch formation by pulling it out from both holding means and supplies it to a thread take-up, it is particularly suitable for sewing machine needles. If the sewing machine is stopped and the presser foot is raised when the sewing machine is located below the top surface of the bed, both holding means remain in the state they were in before the sewing machine stopped, and the sewing machine is stopped when the sewing machine needle is located above the top surface of the bed. It is characterized in that both holding means are opened when the presser foot is raised.

Conventionally, as described in Tsubakinusho No. 57-148837, both holding means are opened by stopping the sewing machine and raising the presser foot, thereby facilitating threading work and taking out the fabric from the seamed part. was developed, but according to this, both holding means would open even when the presser foot was raised with the sewing machine needle stuck into the fabric in order to rotate the fabric during sewing.
There was a drawback that the amount of needle thread for the next first stitch could not be accurately controlled.

there were.

This invention solves the above-mentioned drawbacks of the conventional art by maintaining both holding means in the state before stopping when the sewing machine is stopped with the sewing machine needle located below the top surface of the bed and the presser foot is raised. With the goal.

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

Regarding the configuration of the mechanical part, the sewing machine 1 has a main shaft (not shown) that rotates in conjunction with a drive source, a needle bar 3 that fixes a needle 2 with a needle thread T at its lower end and moves up and down in conjunction with the main shaft, and a needle bar 3 that moves up and down in conjunction with the main shaft. A known thread take-up is provided with a thread take-up 5 that supports the needle thread T between the thread spool 4 and the needle 2 as a thread supply source, and moves around the main shaft to reciprocate between two positions so as to tension and relax the needle thread T. The relationship between the needle 3 and the balance 5 with respect to the rotation angle of the main shaft is as shown in FIG.

The first holding means 6 and the second holding means 7 include a balance 5 and a bobbin 4.
The electromagnet (first solenoid) 8 and the electromagnet (second solenoid) 9 are arranged separately at the front and the front in the needle thread supply direction from the bobbin 4 to the thread take-up lever 5 on the needle thread path between the thread take-up and thread take-up. , a pair of holding plates 10 and 11 that immovably clamp the needle thread T when excited and movably release the needle thread T when de-energized.

The feeding body 12 is an eccentric cam 13 that rotates in conjunction with the main shaft.
The free end of the holding means 6 and 7 is arranged in relation to the needle thread warp so that the needle 2 is lower than the bed surface as shown in FIG. The movement of the needle 2 and the thread take-up lever 5 is adjusted so that the needle thread path between the two holding means 6 and 7 is increased during the period when the needle thread take-up lever 5 is located at the lower stop section (lower stop section), and the thread take-up length is minimized until the thread take-up is tensioned by the thread take-up lever 5. Make it relevant.

Further, the rotating body 15 is rotatable in proportion to the moving distance when the needle thread T moves along its path.
It is placed between 7.

Regarding the electric circuit, the feedout detection device 16 generates one pulse each time the rotating body 15 rotates by a certain angle.

The main shaft detection device 17 is connected to the main shaft or a part linked thereto, and detects a specific rotation angle of the main shaft corresponding to the period when the needle 2 is located below the bed surface, and detects a low level (hereinafter referred to as L). ) generates a position signal. The presser foot lift switch 18 is disposed in relation to the movement path of the known presser foot supporting the presser foot at its lower end, and is used to raise the presser foot to a specific position by appropriate means. ) generates a signal. Drive switch 19 is sewing machine 1
This is installed in the drive circuit (not shown) of the main shaft and generates a day signal when the main shaft is stopped. The counter 20 is reset by a position signal from the spindle detection device 17 and counts pulses from the bareness detection device 16.

The setting device 21 consists of a digital switch that is set using a dial, and is set according to the length of needle thread T required to form one stitch (which varies depending on conditions such as the thickness of the fabric, the width of the needle, and the feed pitch). The length of the needle thread T to be fed out is set, and a different digital code is generated in response to the set length. This digital code is related to the number of clock pulses from the payout detection device 16 which corresponds to the rotation angle of the rotating body 15 which is proportional to the payout amount. A comparison circuit 22 compares the output values of the counter 20 and the setting device 21, and generates a day coincidence signal when the two match. The flip-flop FF is reset by the position signal from the spindle detection device 17, and the Q terminal output is set to L, and the comparison circuit 2
The match signal from 2 inverts the Q terminal output from L to 2. The operating circuits 23 and 24 are connected to energize the first solenoid 8 and second solenoid 9 in response to the H signal, and are closed to demagnetize them in response to the L signal. The timer TM consists of a monostabilized multipipulator,
A pulse is generated by detecting the rise of the L signal (position signal) from the spindle detection device 17.

Timer TM2 consists of a capacitor C and a resistor R.
The comparator P is operable to receive a pulse from the timer TM via the intensifier B and output an H signal until a certain period of time has elapsed since then. Note that G, to G6 are AND gate circuits, 1 is an inverter, and presser foot lift switch 18, drive switch 19, and gate G constitute a presser foot detection device 25, which detects the presser foot when the sewing machine is stopped. Generates a thread loosening signal when it rises to a specific position.

Next, these effects will be explained. When the presser foot is lowered and the sewing machine 1 is driven, the output of the presser foot detection device 25 becomes L, so the gates ○3 and G4 are opened and the output state of the flip-flop FF is output as is.

On the other hand, in conjunction with the main shaft, the needle bar 3, the thread take-up lever 5, and the ejecting body 12
reciprocates along the needle birch curve, the balance curve, and the steering curve shown in FIG. The forward movement of the line drawing body 12 in the counterclockwise direction in FIG. Since the flip-flop FF is reset by the H signal from the circuit 17 and its Q terminal output is L, the output of the gate G3 is L and the output of the gate G4 is 1. Furthermore, when the main shaft is rotating at a predetermined speed or higher, the output of the comparator P becomes 0 as described later, so at the above-mentioned main shaft rotation angle position, the first solenoid 8 is demagnetized and the second solenoid 9 is energized. Therefore, the needle thread T is drawn from the bobbin 4 between the holding means 6 and 7 by the length of the needle thread path increased by the forward movement of the line drawing body 12. As the needle thread T is unwound from the bobbin 4 in this way, the rotating body 15 rotates, and as a result, the line detection device 16 generates a number of clock pulses proportional to the rotation angle. This clock pulse is counted by the counter 20, and the count value is -
input to the other input section. When the calculated value of the counter 20 matches the output of the setting device 21, the comparison circuit 22 outputs a day matching signal, which causes the Q of the flip-flop FF to be
Since the terminal output is reversed from the aforementioned L to day, the first solenoid 8 is energized and the second solenoid 9 is demagnetized. Therefore, after the needle thread T of a predetermined length is fed from the bobbin 4 between the two holding means 6 and 7 by the forward movement of the feeding body 12, the second holding means 6 holds the needle thread T so that it cannot pass through. The second holding means 7 releases the needle thread T so that it can pass therethrough. If the needle thread T of the planned length is exposed during the forward movement of the line drawing body 12, the subsequent exposed body 12
During the forward movement, the needle thread T loosened between the needle 2 and the second holding means 7 is pulled back between the holding means 6 and 7. Further, the protruding body 12 returns to its original position until the needle thread T is next tensioned by the thread take-up 5. Therefore, during the next period of tensioning the needle thread by the thread take-up lever 5, the needle thread T fed in between the two holding means 6 and 7 is pulled out as the thread take-up 5 rises, and the first holding means 6 and between the stitches are The needle thread T is tensioned, and the stitch is tightened and knotted with a predetermined strength. When the sewing machine 1 is stopped and the presser foot is raised, the output of the presser foot detection device 25 becomes 1 and the gate G2 is opened. The output of the detection device 17 is L
Since gates ○3 and G4 are held open, even if the sewing machine is stopped, if line drawing body 1
2, even if the needle thread T is inserted between both holding means 6 and 7 due to an amount from the outside, the needle thread T of a predetermined length set by the setting device 21 is inserted between both holding means 6 and 7. 6,7
If the output of the flip-flop FF is reversed when the needle is inserted in the middle, the outputs of the gates G3 and G4 are also reversed, so that the first holding means 6 prevents the needle thread from becoming tacky, and the cloth is again removed. If you lower the presser foot and start the sewing machine, it will continue to start from that state.

That is, in the lower stop section, even if an external force is applied to the needle thread T with the sewing machine stopped and the presser foot raised, there is no effect on the bare needle thread for each stitch formation. On the other hand, if the sewing machine is stopped during the upper stop section where the needle 2 is positioned above the bed surface and the presser foot is raised to a predetermined position, the output of gate G2 becomes 1, and the output of gate G3 becomes When G4 is closed, these outputs become L and both solenoids 8
.

As mentioned above, while the sewing machine is running, both solenoids 8,
9 is controlled, but when the sewing machine is stopped, the timer TM,
Since the input of the comparator P does not change, the output of the comparator P becomes L after a predetermined time period determined by the time constant of the timer TM2 has elapsed.

As a result, gates G5 and G6 are closed, and both solenoids 8 and 9 are demagnetized, thereby preventing overheating while the sewing machine is stopped. As described above, this invention uses two holding means that can pinch and release the needle thread, and a thread remover that is placed on the needle thread path between the two holding means and operates in synchronization with the thread take-up. In a needle thread supply device that actively draws out a needle of the required length from a supply source for each stitch formation and supplies it to a thread take-up, when the sewing machine is stopped and the presser foot is raised, the sewing machine needle When the sewing machine is located above the top surface, both holding means are opened, and at other times, both holding means are left in the same state as before the sewing machine stopped. Even if the presser foot is raised to rotate the fabric around the needle with the needle stuck into the fabric, both holding means remain in the state they were in before they stopped, so the needle thread is removed from the next first stitch. The amount of line drawing can be accurately controlled, improving the quality of sewing, and both holding means open when the needle is pulled out of the fabric, making it easier to remove the fabric from the seam and thread the thread. There is. In each of the above embodiments, basic data regarding the length of needle thread required for tying each stitch is set by manual operation of a digital switch. Based on the data detected by a known detection means to determine the set position of the needle swing mechanism or the momentum of the needle swing mechanism or cloth feeding mechanism, pre-stored yarn amount data is read out from the storage device, and this data is used as the basis for the unreeling length. Alternatively, data calculated based on the detected data may be input to the comparator circuit 22 as basic data for the feeding length, or data stored in the storage device may be used to block the needle swinging mechanism. In a sewing machine of a type that operates a fabric feeding mechanism, the comparator circuit 18 simply reads out the pre-stored thread amount data using the stored data, or uses the data calculated by using the stored data as the basic data for the unreeling length. It is also possible to input the .

Furthermore, in addition to data related to needle swing and fabric feed, the data corresponds to detection data from a fabric thickness detection means that uses a potentiometer to detect changes in the position of the presser foot due to fabric thickness, and the type of fabric thread and weaving method. The feeding amount may be set by combining data obtained through experiments in advance. Further, in the above embodiment, the feeding body 12 swings in conjunction with the cam body 13, but as shown in the first embodiment of Tokuiso Sho 57-82712, the feeding body 12 is attached to the outer periphery facing the needle thread path. The bare body on which the cam surface is formed may be rotated.

In the above embodiment, the L signal (position signal) from the spindle detection device
The timing at which this occurs coincides with the lower stop section where the needle is located below the top surface of the bed, and the signal is used to control both holding means and to distinguish between the upper stop section and the lower stop section of the sewing machine.
A device (second spindle detection device) may be separately provided for generating a (second) position signal for reversing the state of the holding means prior to line setting of the needle thread.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the main parts, FIG. 2 is a block diagram of the electric circuit, and FIGS. 3 and 4 are time charts. Sai' Figure Sai 3 Figure Sai 2 Figure Sai 4 Figure

Claims (1)

[Claims] 1. Disposed on the needle thread path between the thread take-up and the needle thread supply source so as to be spaced apart from each other in the front and back of the needle thread supply direction, and to make it impossible to pass the needle thread by action and to allow the needle thread to pass by non-action. First and second holding means 6, 7 act on the needle thread to
The needle thread path between both holding means is changed so that the length of the path is always increased by a certain distance at times other than when the needle thread is tensioned by the thread take-up, and becomes the shortest by the time the needle thread is tensioned to its maximum by the thread take-up. Feeding bodies 1 and 2 that operate in synchronization with the thread take-up, and engagement with the needle thread associated with the feeding body or in front of the feeding body in the needle thread supply direction, increasing the length of the needle thread path between the two holding means. a feed-out detection device 16 that is displaced in proportion to the operation of the feed-out body or the length of the needle thread fed out by the feed-out body, and generates a yarn amount detection signal corresponding to the amount of displacement;
A first position signal is generated by detecting a specific rotation angle of the main shaft, which is arranged in relation to the main shaft and corresponds to the time when the sewing machine needle is located below the top surface of the bed, and a specific rotation of the main shaft corresponding to the time when the needle thread is relaxed by the thread take-up. A main shaft detection device 17 that detects a corner and generates a second position signal, and a setting device that can generate a setting signal corresponding to the length of needle thread required to form one stitch in response to different sewing conditions. 21, a comparison circuit 22 which compares the thread amount detection signal and the setting signal and generates a matching signal when they match; A presser foot that can be moved and locked, a presser foot detection device 25 that generates a thread loosening signal in connection with the rise of the presser foot when the sewing machine is stopped, and a presser foot detecting device 25 that is always located before the feeding body in the needle thread supply direction. The first holding means is activated and the second holding means is deactivated, and in relation to the second position signal, the activated and non-activated states of both the holding means are reversed during the period from the generation of the second position signal to the generation of the coincidence signal. The outputs of the first control circuit FF, the spindle detection device, and the presser foot detection device are input, and the thread loosening signal is enabled at times other than when the first position signal is generated, and the thread loosening signal is activated when the first position signal is generated. A second control circuit G_2, G_ has a gate G_2 that disables the signal, and disables both holding means in priority to control by the first control circuit when the thread loosening signal is enabled.
3, G_4, and a needle thread supply device for a sewing machine.