JPH0613780U - Sewing machine thread drawing device - Google Patents

Abstract

(57) [Summary] [Purpose] When sewing thread on a sewing machine, an appropriate amount of thread can be pulled out regardless of the thickness of the thread and the thickness of the sewing material. [Structure] A rotary shaft 1 that reciprocally rotates in relation to a sewing machine mechanism.
And a moving knife 21 that has thread catching portions 21a and 21b at its tip and is fixed to the rotating shaft to reciprocally rotate, and a thread at a thread cutting position when the moving knife returns in cooperation with the moving knife. In a thread cutting device for a sewing machine, which comprises a fixed knife 22 for cutting a thread, a thread pulling piece 8 having a thread catching portion 8a at a position facing the thread catching portion of the moving knife along the lower surface of the moving knife, and a moving knife of the moving knife. The interlocking means 3, 5, 6, 8c for interlocking the thread withdrawing piece with the moving knife during the forward movement, and the interlocking operation between the thread withdrawing piece and the interlocking means immediately before the moving knife moves back to release the thread withdrawing piece. It is composed of thread pulling piece rotating means 7, 7a, 8d, 10, 11 for rotating the yarns beyond the thread cutting position.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to the withdrawal of a thread when the thread is pulled out and cut in a thread trimming operation of a lockstitch sewing machine.

[0002]

[Prior art]

 FIG. 4 is a plan view of a thread cutting device of a conventional sewing machine. In FIG. 4, 20 is a hook, 21 is a moving knife, and 22 is a fixed knife. Reference numeral 21a is a lower thread catching portion provided at the tip of the moving knife, 21b is an upper thread catching portion, and 21c is a pivot of the moving knife.

The above-described conventional thread cutting device for a sewing machine having the above-described configuration operates as follows. When sewing of the sewing machine is completed, a thread trimming signal is sent from a control unit (not shown) to release the thread tension that gives tension to the upper thread, weaken the thread clamping pressure of the upper thread residual adjustment thread tension, and reciprocally rotate. The moving knife starts the thread cutting operation by the moving thread cutting drive mechanism. That is, the moving knife rotates counterclockwise around the fulcrum 21c, the tip of the moving knife advances to the maximum advancing position, and after reaching this position, the moving knife starts rotating clockwise and the yarn path When the bobbin thread is caught by the bobbin thread catching portion 21a at the top and is further rotated clockwise while catching the needle thread by the needle thread catching portion 21b, when the thread cutting position at the tip of the fixed knife is reached. In addition, the moving knife cooperates with the fixed knife to cut both the upper thread and the lower thread.

[0004]

[Problems to be solved by the device]

 However, the above-mentioned conventional technique has the following problems. At the time of thread trimming, in order to pull out the upper thread necessary for sewing, the thread tension applying tension to the upper thread is released, and the upper thread is pulled out by the moving knife 21. The amount of the upper thread pulled out is determined by changing the thread clamping pressure of the upper thread residual adjustment thread tension provided separately from the thread tension. That is, since the length is determined by the friction between the thread and the thread tension, if the thread clamping pressure of the upper thread residual amount adjusting thread tension is weak, the upper thread residual quantity is large, and if it is strong, it is short. Therefore, if the thread becomes thicker, friction will occur between the upper thread and the upper thread residue adjusting thread tension even if the thread clamping pressure of the upper thread residual adjusting thread tension is weakened, and a sufficient amount of the upper thread remaining can be obtained. There are things you can't do. Further, if the thickness of the sewn product becomes large, friction occurs between the upper thread and the sewn product, and even if the thread tension is released, the upper thread catching section 21b of the moving knife 21 catches the upper thread and returns to rotate. However, there was a problem in that the necessary and sufficient needle thread could not be pulled out only by doing this.

The present invention has been made in view of the above problems, and provides a thread withdrawing device for a sewing machine that can withdraw an appropriate amount of the upper thread regardless of the thickness of the upper thread and the thickness of the sewn product. The purpose is.

[0006]

[Means for Solving Problems]

 A thread drawing device for a sewing machine according to the present invention includes a rotary shaft that reciprocally rotates in relation to a sewing machine mechanism, a moving knife that has a thread catching portion at its tip and is fixed to the rotary shaft, and reciprocally rotates. In a thread cutting device of a sewing machine, which comprises a fixed knife which cuts a thread at a thread cutting position when the moving knife moves backward in cooperation with the moving knife, the thread cutting device is fitted on the rotary shaft and extends along the lower surface of the moving knife. A thread drawing piece having a thread catching portion at a position facing the moving knife of the moving knife, interlocking means for interlocking the thread drawing piece with the moving knife when the moving knife moves forward, and immediately before returning of the moving woman. And a rotating means for separating the thread pulling piece from the interlocking means and rotating the thread pulling piece beyond the thread cutting position.

[0007]

[Example of device]

 FIG. 1 is an exploded perspective view showing the structure of a thread drawing device of a sewing machine showing an embodiment of the present invention. The same members as those of the conventional thread cutting device in FIG. 4 are designated by the same reference numerals, and the description thereof will be omitted. Reference numeral 1 is a rotating shaft, which can be rotated by a thread cutting drive mechanism (not shown). Reference numeral 2 denotes a cam, the lower end of which is fixed to the machine frame, a hole into which the rotary shaft 1 can be inserted is formed at the center thereof, and a projection 2a is provided near the outer periphery of the upper end surface. . Reference numeral 3 denotes a holding body, which is fixed to the rotating shaft 1 by a ring-shaped fixing portion 3a, rotatably supports the engaging body 5 via a pin 4, and engages a spring 6 with an arm 3b of the holding body 3. It is bridged over the arm 5a of the united body 5. When the rotating shaft 1 rotates counterclockwise and the lower end 5b of the engaging body 5 contacts the protrusion 2a of the cam 2, the engaging body 5 resists the elastic force of the spring 6 around the pin 4. And clockwise to rotate the upper end 5c downward.

Reference numeral 7 is a latch solenoid, the lower end of which is fixed to the machine frame so that the plunger 7a can take two positions of forward and backward. Reference numeral 8 denotes a picker for pulling out the upper thread, which has substantially the same shape as the moving knife 21 and is provided below the moving knife 21 so as to be covered by the moving knife 21, as shown in FIG. Reference numeral 8a is an upper thread catching section which is provided at the tip of the picker 8 and catches the upper thread. The upper thread catching portion 8a is provided at a position corresponding to the upper thread catching portion 21b of the moving knife 21. Reference numeral 8b is a hole at the center of rotation of the picker 8, into which the rotary shaft 1 coupled to the moving knife 21 can be inserted, and the picker 8 is made to play in the thrust direction by the thrust collar 9. It is fitted and supported on the rotating shaft 1. A notch 8c is formed to have a size capable of engaging with the upper end portion 5c of the engaging body 5. Reference numeral 10 denotes a spring, one end of which is bridged to the picker 8 and the other end of which is bridged to a pin 11 fixed to the machine frame to elastically bias the picker 8 clockwise. Reference numeral 8d is an abutting side, and the tip of the advance / retreat portion 7a of the latch solenoid 7 is bent so that it can abut. The needle thread remaining amount adjusting device of the sewing machine configured as described above operates as follows. When the rotary shaft 1 is rotated counterclockwise by the thread cutting drive mechanism that makes a reciprocating rotary motion, the moving knife 21, the holding body 3, and the engaging body 5 fixed to the rotary shaft 1 are rotated together. As a result, the upper end 5c of the engagement body 5 presses the notch 8c of the picker 8 so as to rotate counterclockwise. That is, the moving knife 21 and the picker 8 integrally rotate in the counterclockwise direction. The tip of the moving knife 21 advances to a position just before the maximum advance position, and at this position, the lower end 5b of the engaging body 5 abuts the protrusion 2a of the cam 2. Then, the engagement body 5 rotates clockwise around the pin 4, the upper end 5c of the engagement body 5 rotates downward, and is disengaged from the notch 8c of the picker 8. The picker 8 rapidly rotates clockwise around the hole 8b by the urging force of the spring 10, and the upper thread is caught on the upper thread catching section 8a provided at the tip of the picker 8 on the thread path. In the state of capturing, the contact piece 8d is rotated until it contacts the tip of the plunger 7a of the latch solenoid 7. After the upper thread is sufficiently pulled out by the picker 8 in this way, the moving knife 21 starts to rotate backward in the clockwise direction, the lower thread is caught by the lower thread catching section 21a, and the upper thread is caught by the upper thread catching section 21b. While catching the needle, when it further turns clockwise and reaches the thread cutting position at the tip of the fixed knife, the moving knife cooperates with the fixed knife to cut both the upper thread and the lower thread. And the thread trimming is completed.

When the next sewing is started, the plunger 7a of the latch solenoid 7 is advanced by the sewing start signal, and the contact piece 8d of the picker 8 is pressed to rotate counterclockwise. , Returning the picker 8 to the initial position where the moving knife 21 is on standby, retracting the advancing / retreating portion 7a by the thread trimming signal at the start of thread trimming, and rotating the picker 8 clockwise to pull out the upper thread. The range is regulated.

It should be noted that the mounting plate of the latch solenoid 7 is provided with an elongated hole, and the mounting position is changed in the advancing / retracting direction by the fixing pin, so that the picker 8 can also adjust the amount of drawing the upper thread. . Further, by changing the fixed position of the cam 2 about the rotating shaft 1, it is possible to change the position where the picker 8 starts rotating clockwise or not to rotate it.

In the above-described embodiment, the example in which the cam mechanism, the latch solenoid, and the like are used to execute the needle thread withdrawing operation of the picker 8 is not limited to this example. A picker 8 is provided via the clutch mechanism. When the clutch is connected, it interlocks with the moving member 21 to rotate in the counterclockwise direction, disengages the clutch at a predetermined position, and biases the picker 8 by a spring. May be rotated clockwise.

[0012]

[Effect of device]

 As described above, the present invention, as described above, includes a rotary shaft that reciprocally rotates in relation to the sewing machine mechanism, a moving knife that has a thread catching portion at the tip and is fixed to the rotary shaft, and reciprocally rotates. In a thread cutting device of a sewing machine, which comprises a fixed knife which cuts a thread at a thread cutting position when the moving knife returns in cooperation with a female member, the thread cutting device is fitted on the rotary shaft and extends along the lower surface of the moving knife. The thread withdrawing piece having a thread catching portion at a position opposite to the thread catching portion of the moving knife, interlocking means for interlocking the thread withdrawing piece with the moving knife when the moving knife moves forward, and immediately before returning of the moving knife. Since the thread withdrawing piece is separated from the interlocking means and the rotating means for rotating the thread withdrawing piece beyond the thread cutting position is provided, an appropriate amount of thread can be withdrawn regardless of the thickness of the cloth. There is an effect.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a thread cutting device for a sewing machine according to the present invention.

FIG. 2 is a plan view of a thread cutting device for a sewing machine according to the present invention.

FIG. 3 is a view showing an arrow A in a part of FIG.

FIG. 4 is a plan view showing a conventional sewing machine device.

[Explanation of symbols]

 1 Rotating Shaft 2 Cam 2a Projection Part 3 Holding Body 5 Engaging Body 6 Spring 7 Latch Solenoid 8 Picker 8a Needle Thread Trapping Part

Claims (1)

[Scope of utility model registration request] 1. A rotary shaft which reciprocally rotates in relation to a sewing machine mechanism, a moving knife which has a thread catching portion at its tip and is fixed to the rotary shaft to reciprocate, and cooperates with the moving knife. In the thread cutting device of the sewing machine, which comprises a fixed knife that cuts the thread at the thread cutting position when the moving knife returns, the thread catching of the moving knife is inserted into the rotary shaft and follows the lower surface of the moving knife. The thread pulling-out piece having a thread catching portion at a position facing the section, interlocking means for interlocking the thread pulling-out piece with the moving knife when the moving knife moves forward, and the yarn pulling-out piece just before the moving knife returns. A thread drawing device for a sewing machine, which is provided with a rotating means which is separated from the interlocking means and rotates the thread drawing piece beyond the thread cutting position.