JPS642707Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a feed frequency control device for a sewing machine.

Prior Art Conventionally, for example, in an overlock sewing machine, the front end and rear end of the work cloth are detected, and after the detection, the required number of stitches are sewn, a cutter is operated to connect the front end and the rear end of the work cloth. A chain cutter device for cutting a chain of threads is employed as necessary. Generally, the stitch number detection means is as shown in FIGS. 7 and 8.
A detected element c such as a permanent magnet piece is attached to a fixed disk b on the sewing machine main shaft a, and a detecting element d such as a Hall element is arranged opposite to the disk b, and one pulse is generated per rotation of the sewing machine main shaft a. A device adapted to generate a signal is employed. However, the state of the stitch number detection means at the time when it starts counting the number of stitches based on detection of the front edge or rear edge of the work cloth is the same number of stitches in the state shown in FIG. 7 and the state shown in FIG. Even if this is done, there will actually be a difference in the amount of cloth feed for one stitch.
That is, in FIG. 7, the detection is performed immediately, and in FIG. 8, the detection is performed approximately after the main shaft a of the sewing machine has rotated once. For this reason, the chain cannot be cut close to the front and rear ends of the work cloth, and the effect of providing the chain cutter device is reduced by half.

Purpose In view of these circumstances, the present invention attempts to provide a sewing machine feed frequency control device that can minimize the difference in cloth feed amount that has conventionally occurred.

Embodiment Below, an embodiment of the present invention will be described in which the present invention is embodied in an overlock sewing machine equipped with a chain cutter device configured to cut a chain of threads connected to the front and rear ends of a work cloth.

In the drawings, a frame 1 of an overlock sewing machine includes a throat plate 2 and a cloth plate 3 that together with the throat plate 2 constitutes a workpiece cloth support surface. needle 4
is attached to the lower end of the needle bar 5, and forms an overlock stitch at the edge of the workpiece cloth 6 in cooperation with an overlooper and an underlooper (not shown).

The presser foot foot 7 is located on the throat plate 2, and is attached to a presser foot support arm 8 linked to a presser foot lifting pedal (not shown). It is always urged downward by a cloth pressing spring (not shown) stretched between the two. The feed dog 9 comes and goes through a feed dog narrow groove 10 formed in the throat plate 2, and works in conjunction with the sewing machine main shaft 11 to convey the work cloth 6 in cooperation with the presser foot 7.
A known four-feed motion is performed in the order indicated by the arrows in the figure.

A U-shaped support 12 is attached to the frame 1 on the cloth feeding side of the throat plate 2, and the support 12 supports a shaft 13 so that it can rotate and move in the axial direction. are doing. Also, the axis 1
3 has a movable blade 14 fixed to one end and a pinion 15 fixed to the other end. The fixed blade 16 is fixed to the frame 1 adjacent to the throat plate 2, and cuts the thread chain in cooperation with the movable blade 14. A coil spring 17 is stretched around the shaft 13 between the support 12 and a collar 18 fixed to the shaft 13, and normally biases the shaft 13 to the right in FIG. Movable blade 14
The fixed blade 16 is pressed against the fixed blade 16 .

The solenoid 19 is attached to the frame 1, and a rack 20 that meshes with the pinion 15 is fixed to its armature 19a. The solenoid 19 is of a type in which the armature 19a is attracted upward when energized, and the armature 19a is always drawn by the coil spring 22 stretched between the collar 21 fixed to the armature 19a and the solenoid body. is prominent. Further, in order to detect the front and rear ends of the workpiece cloth 6, a light emitting element 23a is provided on the frame 1, and a light receiving element 23b is provided on the needle plate 2, slightly on the cloth feeding side of the vertical movement path of the needle 4. installed. A known chain suction pipe 50 is disposed on the fabric delivery side of the movable blade 14, and sucks the chain of yarn cut by the movable blade 14 and the fixed blade 16 into a waste reservoir (not shown). to be discharged.

A pulley 24 as a rotating body is attached to the end of the sewing machine main shaft 11, and five detected elements 25 made of permanent magnets etc. are mounted around the pulley 24.
are fixed at approximately equal intervals. Note that the rotating body is not limited to the pulley 24, and any form of rotating body may be used as long as it is fixed to the sewing machine main shaft 11 or a shaft interlocking therewith. Further, a mounting body 27 fixed to the frame 1 with screws 26 extends at a position facing the pulley 24, and this mounting body 27 has a single piece that cooperates with the five detected elements. A detection element 28 such as a Hall element is provided.
The detected element 25 and the detection element 28 are located in an area (indicated by X in FIG. 5) corresponding to the entire area (indicated by X in FIG. In other words, it is provided in the area where the work cloth 6 is actually transferred. Note that the area indicated by Y in FIG. 5 corresponds to an area where the feed dog 9 is below the upper surface of the throat plate 2 (area indicated by Y in FIG. 4) and the work cloth 6 is not transferred. ing.

In FIG. 6, the cloth edge detection circuit 23 includes the light emitting element 23a and the light receiving element 23b, and when the front edge of the work cloth 6 is detected, its output changes from a low level voltage signal to a high level voltage signal. When the rear end of the work cloth 6 is detected, the voltage signal changes from a high level to a low level. The first monostable multivibrator 29 generates an output signal in response to the rise of the output of the cloth edge detection circuit 23, and the second monostable multivibrator 30 is connected to the cloth edge detection circuit via an inverter 31. 23, and its cloth edge detection circuit 23
Generates an output signal in response to the falling edge of the output.

The OR circuit 32 receives the outputs of the first and second monostable multivibrators 29 and 30 as inputs. The flip-flop circuit 33 is a NAND circuit 3
The NAND circuit 34 receives the output of the OR circuit 32 and the output of the NAND circuit 35, and the NAND circuit 35 receives the output of the OR circuit 32 and the output of the NAND circuit 35.
, the output of the reset circuit 36 when the power is turned on, and the output of the third monostable multivibrator 37 are input. The AND circuit 38 receives as inputs the output of the NAND circuit 34 of the flip-flop circuit 33 and the output generated by the detection element 28 which is waveform-shaped by a waveform shaping circuit 39. The frequency divider 40 divides the number of output pulses from the AND circuit 38 into 5 pulse signals, which are generated from the detection element 28 during one revolution of the sewing machine main shaft 11, into one feed count signal. one part
The output of this frequency divider 40 is sent to a binary counter 41 for counting the number of feeds.
is applied as an input. The binary counter 41 has an OR circuit 42 between the output of the reset circuit 36 and the output of the monostable multivibrator 37.
It is applied as a reset signal via.

A front end feed frequency setting device 43 sets the number of feeds from when the front end of the work cloth 6 is detected until the solenoid 19 is energized and the movable blade 14 is operated. is after the rear end of the work cloth 6 is detected and then the solenoid 19
This is to set the number of feeds until the movable blade 14 is activated. The selection circuit 45 is
When the front end of the workpiece cloth 6 is detected by the output signal from the cloth edge detection circuit 23, the front end feed number setter 43 is selected, and when the rear end of the workpiece cloth 6 is detected, the rear end feed number setter 43 is selected. Select 44.

The comparator circuit 46 generates an output signal when the number of feeds set by the feed count setter 43 or 44 selected by the selection circuit 45 and the count number of the binary counter 41 match by one. It is supplied to the fourth monostable multivibrator 47 in the next stage and the third monostable multivibrator 37. The drive circuit 48 controls the solenoid 1 based on the output of the fourth monostable multivibrator 47.
9 is driven for a certain period of time.

Next, the effect will be explained. Now, when power is applied to the electric control circuit shown in FIG. 6 prior to the start of sewing, the flip-flop circuit 33 and the binary counter 41 are reset by a reset pulse generated by the reset circuit 36 when the power is turned on. At this time, since the solenoid 19 is energized, its armature 19a protrudes due to the action of the coil spring 22, and the shaft 13 is rotated clockwise in FIG. 1 via the rack 20 and pinion 15, causing the movable blade 14 to rise. in a rotated position.

In this state, the workpiece cloth 6 is fed between the presser foot 7 and the feed dog 9, and the sewing machine is driven (this driving may be performed automatically based on the detection of the workpiece cloth, or by depressing the foot pedal). (There are various methods such as A sewing machine signal is generated. Moreover, the pulse signal is generated in accordance with the timing when the feed dog 9 protrudes above the throat plate 2 and the workpiece cloth 6 is actually fed. However, since the flip-flop circuit 33 has been reset at this time, the AND circuit 38 does not generate an output signal.

When the work cloth 6 moves forward and its front end blocks the light from the light emitting element 23a to the light receiving element 23b, the output of the cloth edge detection circuit 23 changes from a low level voltage signal to a high level voltage signal. An output is generated from one monostable multivibrator 29, and a flip-flop circuit 33 is set. At the moment of this set, the pulse output from the detection element 28 comes to appear as it is from the AND circuit 38, and the pulse output is divided into one-fifth of the number of pulses by the frequency divider 40 and is outputted to the binary counter 41. is applied to Suppose that the positional relationship between the instantaneously detected element 25 and the detecting element 28 of the set of flip-flop circuits 33 is the fifth one.
Assuming that the feed dog 9 is in the upward stroke and has fed approximately three-fifths of the feed pitch of one stitch, the feed dog 9 is in the upward stroke.
Two pulses are generated from the detection element 28 before the remaining two-fifths of the feed stroke is completed and the needle plate 2 descends from the upper surface of the throat plate 2, and in the next feed stroke, the feed dog 6 is raised to approximately two-thirds. At the end of the feeding stroke, the detection element 28
One pulse is supplied to the binary counter 41 from the time frequency divider 40 where the third pulse is generated. In this way, the counter 41 has
Regardless of the position of the instantaneous feed dog 9 in the set of the flip-flop circuit 33, one pulse signal is supplied to the binary counter 41 for each substantial feed operation by the feed dog 9. Become.

As a result, as the front end of the workpiece cloth 6 is detected, the number of feeds set by the front end feed number setter 43 via the selection circuit 45 based on the output from the cloth edge detection circuit 23 matches the content of the binary counter 41. An output is generated from the time comparator circuit 46, which energizes the solenoid 19 and attracts its armature 19a against the action of the coil spring 22. The thread chain connected to the front end of the work cloth 6 is cut by the movable blade 14 and the fixed blade 16 at a position close to the front edge of the work cloth 6.
Further, when the comparator circuit 46 outputs, a reset pulse is generated from the third monostable multivibrator 37, and the binary counter 41 and flip-flop circuit 33 are reset, and the circuit shown in FIG. The situation will be similar to that of

After the required sewing is completed, the solenoid 19 is energized based on the detection of the rear end of the workpiece cloth 6 to cut the thread chain, which is substantially the same as the case at the front end of the workpiece cloth 6. However, at this time, when an output appears from the cloth edge detection circuit 23 based on detection of the trailing edge of the workpiece cloth 6, the flip-flop circuit 33 is set via the second monostable multivibrator 30, and at the same time the selection circuit 45 is set. Selection of the trailing end feed number setting device 44 is performed via.

In the above embodiment, the number of detected elements is 5.
However, the larger the number, the smaller the difference in the actual cloth feed amount when the number of feeds is set to be the same. Further, in the above embodiment, five detected elements 25 are provided on the pulley 24 as a rotating body, and one detection element 28 is provided on the mounting body 27. (b) Providing a plurality of detection elements on the rotating body and providing one detected element on the mounting body; (c) Various modifications can be considered, such as providing one detection element on the rotating body and providing a plurality of detected elements on the mounting body.

Note that this invention is not limited to the chain cutter device described above, but also a tape cutter device that cuts the tape to be sewn onto a workpiece fabric adjacent to the front and rear ends of the workpiece cloth, or a tape cutter device that automatically drives the sewing machine after the required number of feeds. It can be widely applied to sewing machines, such as devices designed to stop the machine.

Effects As described in detail above, the present invention has the main shaft 11 of the sewing machine.
Alternatively, a mounting part body 27 placed in a stationary state is provided at a position facing the rotating body 24 attached to a shaft that rotates in conjunction with the main shaft 11 of the sewing machine, and the inside of the mounting part body 24 and the rotating body 24 are provided. A detected element 25 is provided on one of them, a detection element 28 is provided on the other,
One of the detected element 25 and the detection element 28 is provided, and the other is provided with a plurality of them at approximately equal intervals, and these elements are spread over approximately the entire area where the feed dog 9 protrudes above the work cloth support surface. This is because the multiple signals generated from the detection element 28 during one rotation of the sewing machine main shaft 11 are used as feed count signals for one feed, and when the signals for the required feed count are received, the functions of the sewing machine are controlled. When the number of times of cloth feeding is set to a certain value, a substantially constant cloth feeding amount can always be ensured without causing a difference in the actual cloth feeding amount as in the conventional method.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the overlock sewing machine with the chain cutter device attached, Fig. 2 is a sectional view taken along the - line in Fig. 1, Fig. 3 is an explanatory diagram showing the operation of the feed dog 9, Fig. 4 5 is a front view of a detection means for generating a feed count signal, FIG. 5 is a right side view of the detection means, and FIG. 6 is an electric control circuit diagram. 7 and 8 are explanatory diagrams corresponding to FIG. 5 showing a conventional example. In addition, in the figure, 1 is the frame, 2 is the throat plate, 4 is the needle, and 6
is the work cloth, 7 is the presser foot, 9 is the feed dog, 11 is the sewing machine main shaft, 12 is the support, 13 is the shaft, 14 is the movable blade, 15 is the pinion, 16 is the fixed blade, 19 is the solenoid, and 19a is the armature. , 20 is easy,
23 is a cloth edge detection circuit, 23a is a light emitting element, 23b
2 is a light receiving element, 24 is a pulley, 27 is a mounting body, 2
8 is a detection element, 33 is a flip-flop circuit, 3
6 is a reset circuit, 38 is an AND circuit, 40 is a frequency divider, 41 is a binary counter, 43 is a front end feed number setter, 44 is a rear end feed number setter, 45 is a selection circuit, 46 is a comparison circuit, 48 is the drive circuit.

Claims (1)

[Claims for Utility Model Registration] A sewing machine including a presser foot 7 disposed on a work cloth support surface, and a sewing machine that retracts from the work cloth support surface and works in cooperation with the work cloth foot 7 to transfer the work cloth 6. In a sewing machine equipped with a feed dog 9 that performs a known four-feed motion in conjunction with the main shaft 11, the sewing machine main shaft 11 or its sewing machine main shaft 1
A rotating body 2 attached to a shaft that rotates in conjunction with 1.
4, a mounting body 27 placed in a stationary state at a position facing the rotating body 24, and a detected element 25 on one of the mounting body 27 and the rotating body 24, and a detected element 25 on the other. Detection element 2
8 are provided, one of the detected element 25 and the detection element 28 is provided, and the other is provided with a plurality of them at approximately equal intervals;
The above-mentioned feed dog 9 is provided corresponding to substantially the entire area protruding above the work cloth support surface, and the above-mentioned detection element 28 detects a plurality of noises generated during one rotation of the sewing machine main shaft 11. A feed number control device characterized in that the signal is a feed number signal for one feed, and feed number control circuits 40, 41, etc. are provided for controlling the functions of the sewing machine when a signal for a required number of feeds is received.