JPH0346713Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a sewing machine equipped with a device that controls the rotation of a feeding body to feed and feed the required length of needle thread from a bobbin for each stitch formation. The present invention is characterized in that when the cloth is taken out of the sewing machine seam after being sewn, the needle thread is let out from the bobbin winding.

Conventionally, in sewing machines that are not equipped with a thread cutting device that cuts the sewing thread connected to the fabric at the bottom of the fabric, when the fabric is removed from the seam section of the sewing machine after sewing, the resistance of the bobbin winding and the thread path between the threads is used to cut the fabric. Since the seams are stretched, the seams tend to be pulled, especially in the case of thin fabrics, which has the disadvantage of deteriorating the quality of the seams.

With this device, when the presser foot is raised to take out the fabric from the seam of the sewing machine, the needle thread is pulled in the direction in which it is fed out, and while a predetermined tension is generated, the needle thread is actively removed from the bobbin winding by the feeding device. It is an object of the present invention to solve the above-mentioned drawbacks of the conventional method.

Examples of this invention will be described below with reference to the drawings.

About the configuration of the mechanical part The sewing machine 1 has a well-known main shaft (not shown) that rotates in conjunction with a drive motor (not shown), and a needle 2 with an upper thread T fixed at the lower end and moves up and down in conjunction with the main shaft. The needle bar 3 supports the needle thread T between the needle bar 3, the bobbin 4 as a needle thread supply source, and the needle 2, and reciprocates between two predetermined positions in conjunction with the main shaft so as to tension and relax the needle thread T. The needle bar 3 is equipped with a thread take-up device (not shown) that operates in conjunction with the thread take-up lever 5 and a thread trimming signal that is generated as needed to cut the needle thread T connected to the fabric below the bed. stitch width and feed dog (not shown)
This is a known method in which the amount of feed and the direction thereof are controlled based on information stored in a storage device in advance.

As shown in Fig. 1, the upper thread T is
From there, the thread is stretched over the thread take-up lever 5 via the thread guide 6, thread presser device 7, feeding device 8, thread guide 9, and tension detection device 10.

The thread presser 7 includes a pair of dish-shaped holders 11,
11 and an electromagnet (thread presser solenoid) 12, and when the electromagnet 12 is energized, both holders 11, 11
The holding bodies 11, 11 are brought into pressure contact with each other, and the pressure contact between the two holding bodies 11, 11 is released by de-energizing them.

The feeding device 8 consists of a driving roller 14 fixed to the output shaft of a stepping motor (hereinafter referred to as feeding motor) 13, and a driven roller 17 supported at one end of a swinging arm 16 that can swing freely around a shaft 15. Therefore, the driven roller 17 is always pressed against the driving roller 14 by the acting force of the coil spring 18 stretched between the swinging arm 16 and the machine frame.

The tension detection device 10 includes a thread guide section 1 that is arranged at a distance between the feeding device 8 and the thread take-up thread 5 on the upper thread path.
9, 19 and the upper thread T between both thread guide parts 19, 19
, a sensing arm 20 that always contacts with a weak elastic force so as to curve its path, and a tension detection switch that generates a thread tension signal when the sensing arm 20 is displaced to a predetermined position against the elastic force. It consists of 21.

Regarding the electric circuit Although the position detection device 22 is not shown, it consists of a rotary plate fixed to the main shaft and a detector for detecting it, and as shown in FIG. A high level signal (hereinafter referred to as H) is generated by detecting the rotation angle of the corresponding main shaft, and a low level signal (hereinafter referred to as L) is generated in other cases.

Although not shown, the fabric thickness detection device 23 includes a movable part that rotates forward and backward in conjunction with the vertical movement of a presser foot that supports a presser foot at its lower end, and a voltage (fabric thickness signal D) corresponding to the rotational position of the movable part. It consists of a volume that generates.

Although not shown, the presser foot lift switch 24 is fixedly disposed within the movement path of the presser bar, and generates an H signal when the presser bar is raised to a predetermined position.

The memory circuit 25 stores information about the swing width of the needle bar 3 for each stitch (stitch width signal Y) and information about the horizontal movement amount of the cloth feed dog (feed amount signal X). The information is from the position detection device 22
At the rising edge of the output, the information corresponding to the next stitch is read out via the pattern control circuit 26, and these pieces of information are sent to the latch circuit 27 as the stitch width signal Y and the feed amount signal X, and at the same time, the stitch width signal Y is also sent to the latch circuit 28, and the feed amount signal X is also sent to the latch circuit 29. Note that the latch circuit 28 is connected to the position detection device 2.
The latch circuit 2 is operated via the one-shot MS ₁ and the inverter 1 in relation to the rise of the output of the latching circuit 2.
7 and 29 operate in conjunction with the fall of the position detection device 22, and each latch circuit outputs the input as it is by operation.

The needle swing motor 30 is used to operate the needle bar swing mechanism, and is driven by a swing width signal Y via a motor control circuit 32 and a motor drive circuit 31. The feed motor 33 is used to operate the cloth feed mechanism, and is driven by a feed amount signal X via a motor control circuit 35 and a motor drive circuit 34.

The setting device 36 sets the needle thread payout amount required for each stitch formation based on the latch circuit 27 and each signal X, Y, and D inputted through the latch circuit 37 which is activated at the same time. For example, the third
The configuration is as shown in the figure. That is, a value k1·P is obtained by multiplying the square root P of the sum of the square value of the feed amount signal X and the square value of the swing width signal Y by a coefficient k1, and a value k2D is obtained by multiplying the material thickness signal D by a coefficient k2. Add "k"
1P+k2D'' and add the coefficient k3 to this to obtain the needle thread length L required to form one stitch, and based on this value, the signal l corresponding to the rotation angle of the motor 13 calculated by the feed-out rotation amount calculator. Latch circuit 3
8 as one input.

The motor drive circuit 40 includes gate circuits _G1 to L
When receiving a signal from the gate circuit G1, the fall of the output of the one-shot MS ₂ is detected and the payout motor 13 is rotated by the amount of input data from the latch circuit 38, and when receiving an H signal from the gate circuit _G1 , the oscillator It acts to rotate the feeding motor 13 in accordance with the output pulse of 39.

The solenoid operating circuit receives an H signal from the gate circuit _G2 to energize the thread presser solenoid 12, and receives an L signal to demagnetize the thread presser solenoid 12.

This invention has the above structure, and its operation will be explained next.

In the sewing state, since the presser foot is lowered, the presser foot lift switch 24 is at "L", which opens the gate _G2 , so that the output of the position detection device 22 of the thread presser solenoid 12 becomes H. When the output becomes L, it is demagnetized.

Next, of the amplitude signal Y and the feed amount signal X read out from the memory circuit 25 to control the needle bar swing mechanism and the cloth feed mechanism, the feed amount signal An amplitude signal Y is output from the latch circuit 29 in connection with the downward movement, thereby operating the feed motor 33, and an amplitude signal Y is output from the latch circuit 29 in connection with the rise of the output of the position detection device 22.
8 and the needle swing motor 30 is operated.
Further, in connection with the fall of the output of the position detection device 22, the feed amount signal X and the amplitude signal Y are activated by the latch circuit 27.
Based on these and the material thickness signal D, the required length of the needle thread is calculated in the setting device 36, and the calculated data is once latched in the latch circuit 38, and the falling edge of the one shot MS ₂ is caught. This is output to the motor drive circuit, and the feeding motor 13 rotates clockwise in FIG. 1 by an angle corresponding to this. That is, the feed motor 13 is the feed motor 33.
At the same time, the thread presser solenoid 12
is de-energized, so the needle thread T is let out from the bobbin 4 by the length calculated by the setting device 36 by the action of the rollers 14 and 17.

Next, when the output of the position detection device 22 rises, the thread presser solenoid 12 is energized via the gate G ₂ and the solenoid operating circuit 41, and the holders 11 continue to hold the upper thread T so that it cannot pass through. Therefore, when the thread take-up 5 is subsequently raised, the holder 11 and the upper thread T between the stitches are gradually tightened, thereby tightening the stitches with appropriate strength and knotting. Thereafter, the same operation is repeated every time one stitch is formed.

When the sewing machine 1 is stopped at the position where the needle 2 comes out of the cloth after the above sewing and the presser foot is raised, the gate _G2 closes and the gate _G1 opens, so that the thread presser solenoid 12 is demagnetized and the holder 11 , 11 is released, and the tension of the needle thread T between the needle 2 and the bobbin spool 4 is released, and the output of the tension detection switch 21 becomes L. When the cloth is taken out from this state, the upper thread T connected to the cloth is tensed, and the tension is detected in connection with the fact that the tension causes the detection arm 20 to move to the solid line position in FIG. 1 against the elastic force. When the output of the switch 21 becomes H, this causes the feeding motor 13 to respond to the output of the oscillator 39.
continues to rotate, and while tension is applied to the upper thread T, the upper thread T is let out from the bobbin winder 4.

In the above embodiment, the feed amount signal and swing width signal stored in advance in the storage device are read out every rotation of the main shaft, and these signals control the movement of the feed mechanism and needle bar swing mechanism for each stitch. In a sewing machine that is capable of sewing a predetermined pattern using a sewing machine, each of the above-mentioned signals read out from the storage device or these signals and the fabric outputted from the fabric thickness detection device in response to changes in the vertical position of the presser foot. The thread feed signal was calculated and determined for each stitch formed based on the thread thickness signal, but the thread feed amount and needle swing amount, or the yarn that was experimentally determined in advance for each different condition of fabric thickness and stored in the storage device. Corresponding yarn amount data may be read out from the amount data group based on the feed signal and swing width signal, or these and the cloth thickness signal.

Further, in the above embodiment, a sewing machine is shown in which the feed mechanism and the needle bar swinging mechanism are controlled based on the feed signal and swing width signal stored in the storage device, but the sewing machine controls the feed mechanism and the needle bar swinging mechanism based on the feed signal and swing width signal stored in the storage device. It may be applied to a sewing machine in which the feed amount and needle swing amount are controlled by operation. In this case, the feeding signal may be calculated in the same manner as described above from the detection signals corresponding to the setting modes of the feed amount and needle swing amount, or from these and the detection signal of the material thickness, or may be determined by experiment in advance. Corresponding yarn amount data may be read out from a yarn amount data group that has been determined and stored.

Furthermore, in the above embodiment, the needle bar is applied to a zigzag sewing machine in which the needle bar swings in a direction crossing the cloth feeding direction, but the cloth is moved in the X-Y coordinate axis direction with respect to the needle bar that moves up and down in a fixed position. It may also be applied to a sewing machine that can sew a zigzag stitch pattern.

In this case, as is well known, two independent power sources, such as motors, are provided for moving the cloth in the direction of the X-coordinate axis and the direction of the Y-coordinate axis.
The amount of needle thread required to form one stitch is expressed as the square root of the sum of the square of the amount of fabric movement in the X-coordinate axis and the square of the fabric movement in the Y-coordinate axis, if the fabric thickness is ignored. Therefore, instead of the feed amount signal and swing width signal of this embodiment, signals for controlling the rotation direction and angle of each of the motors may be used.

As described above, this invention consists of a drive roller 14 arranged to engage the needle thread between the needle and the bobbin spool so that the needle thread is fed out from the bobbin spool by rotation, and a drive roller 14 that adjusts the fabric feed pitch, needle swing width, and fabric thickness. A motor 13 that rotates a drive roller in one direction so as to let out an amount of upper thread related to at least one piece of information from a bobbin winder.
A feeding device consisting of a presser foot that can be moved up and down to press and release the cloth on the upper surface of the bed, and a presser foot lifter that detects the rise of the presser foot to a specific position and generates an upper position signal. With the switch,
A tension detection switch is arranged on the needle thread path ahead of the feeding body in the feeding direction and detects the tension of the needle thread and generates a tension signal. With the configuration including control circuits G1 and 40 that control rotation in one direction, the tension applied to the threads connected to the fabric is detected when the fabric is removed from the sewing machine seam after sewing, and the motor rotates in one direction. As a result, the needle thread is actively paid out from the bobbin spool as the fabric is taken out, so that the formed seam connected to the bobbin spool that serves as the needle thread supply source is strongly pulled and hangs. It has the effect of preventing

[Brief explanation of drawings]

FIG. 1 is a front view of the main parts, FIG. 2 is a block diagram of the electric circuit, FIG. 3 is a block diagram showing details of the setting device, and FIG. 4 is a time chart. 1... Sewing machine, 13... Stepping motor (drive device), 14, 17... Roller (feeding body),
21... Tension detection device, 24... Presser foot lift switch.

Claims (1)

[Claims for Utility Model Registration] A drive roller 14 that engages with the upper thread between the needle and the spool and is arranged so that the upper thread is fed out from the spool by rotation, and a drive roller 14 that adjusts the fabric feed pitch, needle swing width, and fabric thickness. In a feeding device comprising a motor 13 that rotates a drive roller in one direction so as to feed out an amount of needle thread related to each piece of information from a bobbin spool, and a motor drive circuit 40 that controls the drive of the motor, a presser foot that can be moved up and down to press and release the presser foot; a presser foot lift switch 24 that detects when the presser foot has risen to a specific position and generates an upper position signal; a tension detection switch 21 disposed on the needle thread path in the direction ahead to detect the tension of the needle thread and generate a tension signal; and a tension detection switch 21 that controls rotation of the motor in one direction while receiving the upper position signal and the tension signal. A needle thread feeding device for a sewing machine, comprising: a control circuit G1 for controlling the motor drive circuit.