JPH0572239B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for extracting an empty thread ring formed on a throat plate pawl connected to an end of a work cloth from the throat plate pawl in an overlock sewing machine. The present invention relates to an empty ring extracting device for.

[Prior art] Generally, in an overlock sewing machine, an empty thread ring (hereinafter referred to as an empty ring) is formed between the end of the work cloth that has been sewn and the throat plate pawl. It is necessary to cut the work cloth and sew the empty ring connected to the needle and looper into the seam in the next sewing process (back-tuck). This work is usually performed as follows.

First, pull out the hollow ring formed on the throat plate claw connected to the end of the work cloth from the throat plate claw, pass the hollow ring through the needle drop hole, and turn the work cloth towards you to stretch the hollow ring. The hollow ring is held in a hollow ring holder provided in front of the needle drop point, and the stretched hollow ring is cut. At this time, the hollow ring connected from the needle and the looper is held in an elongated state between the needle drop hole and the hollow ring holder. By placing the work cloth on top of this empty ring and starting sewing, the remaining yarn of the empty ring is sewn into the seam when sewing the next work cloth.

[Problems to be Solved by the Invention] Conventionally, the work of extracting the empty ring formed on the throat plate claw from the throat plate claw was done manually, and this also caused the problem that the throat plate claw was small. The work was very tedious.

However, this thread ring forming part is a place where there is a lot of thread waste and cotton dust. Therefore, if a device that automatically extracts the empty ring is simply provided, the operation of this device may be hindered by thread waste or the like.
In such a case, the movable part may interfere with the stitch formation of the needle and may even damage the mechanism.

[Means for Solving the Problems] The present invention employs the following means to solve the above problems. That is, the gist of the present invention is to provide a needle that is moved up and down by a drive mechanism, and a needle plate claw that extends in the cloth feeding direction at a position corresponding to the needle and forms a needle drop hole that opens toward the cloth feeding side. an overlock sewing machine, comprising: a pull-out body that moves from a retracted position that does not interfere with stitch formation of the needle to a pull-out position that pulls out the empty ring on the throat plate claw, and extracts the empty ring formed on the throat plate claw; The empty ring extractor is provided with a position detecting section that detects the position of the extracting body, and when the position detecting section detects that the extracting body is not in the retracted position, the drive mechanism is activated. An empty ring extraction device for an overlock sewing machine is characterized in that it is configured to prohibit operation.

[Function] The empty ring extracting device of the present invention allows the empty ring formed on the throat plate pawl to be pulled out by moving the extractor body provided near the throat plate pawl in the cloth feeding direction along the throat plate pawl. When the needle is drawn out, the position of the needle is detected by the position detection unit, and if the needle is not in the retracted position, it is assumed that the movement of the needle is blocked by thread waste, etc., and the vertical movement of the needle is stopped. prevent damage to the mechanism.

[Embodiment] An embodiment in which the present invention is embodied in a two-needle overlock sewing machine will be described below with reference to FIGS. 1 to 5.

As shown in FIG. 1, two needles 1a and 1b are provided on a frame (not shown) of an overlock sewing machine so as to be movable up and down. A cloth support plate 2 whose upper surface is a work cloth support surface is attached to the machine frame, and a throat plate 3 is attached to one side of the cloth support plate 2. This throat plate 3 includes first and second throat plate claws 4 extending in the cloth feeding direction.
5 are formed in parallel, and at the side of the first throat plate claw 4 and between both throat plate claws 4 and 5, needles extending in the cloth feeding direction and in the same direction correspond to the needles 1a and 1b, respectively. First and second needle holes 6, 7 are formed which are open to the needle hole.

A base 8 is fixed to the machine frame on the cloth feeding side of the throat plate 3, and its upper surface is arranged substantially on the same plane as the work cloth support surface. An empty ring holding plate 10 located on the upper surface of the base 8 is screwed to the tip of a bolt 9 inserted from the back side of the base 8, and is urged downward by a spring 11. The ring holding plate 10, the base 8, and the like constitute a ring holder 12. A cutter blade 14 for cutting the hollow ring 13 (see FIG. 3) is fixed inside the base 8 with a screw 15. The cutting edge 14a of the cutter blade 14 is hidden behind the ring holding plate 10 as shown in FIG. In addition, the base 8
The opposite ends of the front and left sides of FIG. 1 of each of the presser plates 10 and 10 are obliquely cut out to form an empty ring introducing groove 16.

As shown in FIGS. 1 and 2, a rotary solenoid 17 is provided in the machine frame (not shown) near the throat plate 3, and a connecting lever 19 is attached to the drive shaft 18. There is. This connecting lever 19
A pull-out body 21 extending in the cloth feeding direction on the lower surface of the throat plate 3 is supported at its base end on the connecting pin 20 at the tip of the needle plate 3, and the intermediate portion is guided by a guide means (not shown), and the tip of the pull-out body 21 extends in the cloth feeding direction. A pair of first and second extraction portions 22 and 23 are formed to be inserted into the needle drop holes 6 and 7 from below. Then, as shown in FIG. 2, normally the rotary solenoid 17 is demagnetized and the extractor 21 is placed in the retracted position on the cloth feeding side, and when a pedal (not shown) is pressed back, the rotary solenoid 17 is energized. The extracting body 21 is moved to the extracting position on the cloth feeding side. Further, as shown in FIGS. 3a to 3c, hollow rings 13 are inserted into the cloth feeding side surfaces of the first and second extraction parts 22 and 23 from the first needle hole 6 to the second needle. Guide slopes 22a and 23a for guiding to the pit 7 are formed. The guide slopes 22a and 23a are formed to extend from the top to the bottom left in the figure. Note that 24 shown in FIG. 1 and the like is an opening through which a feed dog (not shown) comes and goes.

A Hall element 30 for detecting movement of the extracting body 21 is located on the supporting part 3, facing the side surface of the extracting body 21.
It is fixed by 1. This Hall element 30
When the extracting body 21 is in the retracted position and the magnet 32 embedded in the extracting body 21 is in an opposing position, the output is at a low level, while when the extracting body 21 is not in the retracted position, the output is at a high level. The output of this ball element 30 is connected to a control circuit 40 shown in FIG. 4 by lead wires (not shown).
is input. This control circuit 40 inputs a pre-depression signal of the pedal and a signal from the Hall element 30, and outputs a drive signal to a control unit (not shown) such as a motor that drives the two needles 1a and 1b. , resistors R1 to R4, photocouplers G1 and G2, and an OR gate F. The front pedal depression signal is a signal that becomes high level when the pedal is depressed forward, and becomes low level when the pedal is depressed neutrally or backward. This pedal pre-depression signal is input to the cathode of a photodiode constituting photocoupler G1, while the anode of the photodiode is connected to power supply V1 via resistor R1. The emitter of the phototransistor of this photocoupler G1 is grounded, and the collector is connected to the power supply V2 via a resistor R2 and to the input terminal of the OR gate F. A signal from the Hall element is input to the other input terminal of this OR gate F. Or Gate F
The output terminal of is connected to the cathode of a photodiode constituting photocoupler G2. The anode of this photodiode is connected to the power supply V2 via a resistor R3. The emitter of the phototransistor of this photocoupler G2 is grounded, and the collector is connected to the power supply V1 via a resistor R4.
Outputs a drive signal to the motor control section. If this drive signal is at a high level, the motor will not be driven.
When the level is low, the motor is driven.

Next, the operation of the empty ring extraction device constructed as above will be explained with reference to FIGS. 3 and 5.

Now, during sewing, as shown by solid lines in FIGS. 1 and 2, the rotary solenoid 17
is in a demagnetized state and the extracting body 21 is placed in the retracted position by the action of the return spring,
The first and second extraction parts 22 and 23 are located at the inner part (on the operator side) of the first and second needle drop holes 6 and 7, respectively. At this time, the first and second extraction parts 2
The needles 1a and 1b are moved up and down in front of the needles 2 and 23 to prevent them from colliding with each other. When the sewing is completed, as shown in FIG. 3a, a continuous hollow ring 13 is formed at the end of the work cloth C, and one end of the ring is wrapped between the first and second throat plate claws 4 and 5. There is. Then, when the pedal is pressed backward (point t1 in figure 5),
As the presser foot (not shown) rises, the rotary solenoid 17 is energized. Therefore, as shown in FIGS. 3a and 3b, the extraction body 21 is moved horizontally in the cloth feeding direction, and the first and second extraction parts 22 and 23 at the tips of the extraction body 21 are moved into the first and second needle holes 6. ，
7 to the fabric feed-out side openings (extracting position) of both needle drop holes 6, 7, and press the needle plate claws 4, 5
The empty ring 13 wrapped around is pushed out toward the cloth feeding side (point t2 in the fifth figure).

Thereafter, when the work cloth C is pulled toward the front side (worker's side) and the empty ring is stretched, the empty ring is guided by the guide slope 22a of the first extraction part 22 and the opening of the second needle drop hole 7. position near the area. In this state, release the pedal and press the rotary solenoid 1.
When the operation of 7 is turned off, the extraction body 21 retreats to the cloth feeding side (retreat position) (point t3 in figure 5).
By further pulling the work cloth C toward the front side when the extractor body 21 retreats, the empty ring is positioned at the front side of the needle drop hole 7 and biased toward the second throat plate claw 5 side. This action is due to the action of the guide slope 23a of the second extraction portion 23. As described above, the empty ring 13 can be pulled out from both throat plate claws 3 and 4 without requiring any manual work by simply depressing the pedal.

Then, as shown in FIG. 3c, the groove 16 of the hollow ring holder 12 is
When the hollow ring 13 is drawn into the holder, it is cut by the cutter blade 14 and separated from the work cloth C.
The remaining yarn from the needle and the looper is stretched and remains in a single thread-like state until it is transferred to the empty loop holder 12.
sandwiched between. If the next work cloth is sewn in this state, the remaining threads of the empty loop will be surely sewn into the seams of the next work cloth (t4 to t5 in Fig. 5).

However, if thread waste or the like accumulates in the needle drop holes 6, 7, etc., the extractor 21 will not operate normally. For example, after extracting the empty ring 13, the extracted body 2
1 gets caught in thread waste or the like, the extractor 21 cannot return to the retracted position (point t6 in figure 5).
In such a case, the output signal of the Hall element 30 remains at a high level, so even if the pedal is depressed forward, the two needles 1a, 1 are controlled by the action of the control circuit 40.
The drive signal to the control unit for the motor etc. that drives b remains at high level, and the motor is not driven.
That is, when the pedal is pressed forward, the front pedal pressing signal becomes a low level, the photodiode of the photocoupler G1 lights up, the phototransistor is turned on, and one input terminal of the OR gate F becomes a low level. At this time, when the extraction body 21 is in the retracted position, the output signal of the Hall element 30 becomes a low level, and the output signal of the OR gate F becomes a low level, lighting up the photodiode of the photocoupler G2 and turning on the phototransistor. The drive signal is set to low level and the motor is driven. However, if the extraction body is not in the retracted position and the signal from the Hall element 30 is at a high level, the output of the OR gate F will be at a high level, the photodiode of the photocoupler G2 will not light up, the phototransistor will be turned off, and the drive signal will be It becomes high level and the motor is not driven.

Since the present embodiment is configured as described above, the motor is not driven when the extraction body 21 is not in the retracted position. Therefore, the extractor body 21 and the needle 1
a and 1b will not come into contact with each other, and the mechanism will not be damaged.

It should be noted that other driving means such as a linear solenoid or an air cylinder may be used as a means for driving the movement of the extracting body 21, or the extracting body 21 may be moved manually by connecting the pedal and the extracting body 21 with a wire. You can also do this.
Further, in this embodiment, the case where two needles are used has been described, but the present invention may be applied to an overlock sewing machine having one needle or a plurality of three or more needles. Furthermore, in this embodiment, the Hall element 30
Although the position of the extraction body 21 is detected using the magnet 32, a micro switch or the like may also be used.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to easily and reliably extract the hollow ring formed on the throat plate claw connected to the end of the work cloth, and also to When the body does not operate normally due to thread waste, etc., the needle is prohibited from moving up and down, which provides an excellent effect in that the mechanism will not be damaged.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing one embodiment of the present invention;
The figure is a longitudinal cross-sectional view of the main part, FIGS. 3 a to 3 c are plan views of the main part explaining its operation, FIG. 4 is a circuit diagram of its control circuit, and FIG. 5 is a timing chart explaining its action. . 1a, 1b...needle, 4...first needle plate claw, 5...
...Second throat plate pawl, 6...First needle hole, 7...Second needle hole, 13...Empty ring, 21...Extraction body, 30...Hall element, 32...Magnet , 40...
...control circuit.

Claims (1)

[Scope of Claims] 1. A needle that is moved up and down by a drive mechanism; A needle plate claw that extends in the cloth feeding direction at a position corresponding to the needle and forms a needle drop hole that opens toward the cloth feeding side; moving from a retracted position where the needle does not interfere with stitch formation to an ejection position where the empty ring on the throat plate claw is extracted;
An empty ring extracting device for an overlock sewing machine, comprising a extracting body for extracting an empty ring formed on the throat plate pawl, further comprising a position detecting section for detecting the position of the extracting body, and the position detecting section. An empty ring extraction device for an overlock sewing machine, characterized in that the ring extraction device for an overlock sewing machine is configured to prohibit operation of the drive mechanism when it is detected that the extraction body is not in the retracted position.