JP3674128B2 - Sewing machine with automatic thread trimmer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sewing machine with an automatic thread trimmer configured to cut both upper and lower threads.
[0002]
[Prior art]
For example, in a lockstitch sewing machine, the upper and lower threads are separated along with the movement of the movable blade, and then the movable blade is moved backward to capture the upper and lower threads and draw them toward the fixed blade. An automatic thread trimming device configured to cut between the fixed blade and the movable blade is provided. In this configuration, the return timing of the movable blade is determined by the upward movement of the balance from the lowest point to the highest point, and the upper thread ring that intersects the lower thread is tightened, and the upper and lower threads are connected to the work cloth. The timing at which the contact is formed is set, and the upper and lower threads are captured and cut while the balance is raised.
[0003]
[Problems to be solved by the invention]
However, in conventional sewing machines, when both the upper and lower threads are captured and cut, the thread trimming operation ends and the sewing motor does not stop immediately due to inertia even if the machine motor is de-energized. The work cloth is stuck and the work cloth cannot be removed. For this reason, conventionally, a clutch mechanism is provided between the sewing needle and the drive shaft (spindle shaft) of the sewing needle, and when the sewing needle and the spindle are separated by this clutch mechanism, the lowering position of the sewing needle at the end of the thread trimming operation is determined. Adjustments were made, and there were problems such as a complicated configuration and high cost.
[0004]
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide a sewing machine with an automatic thread trimming device that can finish the thread trimming operation with the sewing needle and the needle plate sufficiently separated without providing a clutch mechanism. Is to provide.
[0005]
[Means for Solving the Problems]
In order to achieve the above-described object, the sewing machine with an automatic thread trimming device according to claim 1 of the present invention works by tightening the upper thread ring intersecting the lower thread by operating the balance in synchronization with the vertical movement of the sewing needle. A sewing machine with an automatic thread trimmer that forms upper and lower thread threads on the cloth and cuts both the upper and lower threads in synchronization with the operation of the balance, and has a movable blade and a fixed blade located below the needle plate. Thread cutting means for moving the upper and lower threads toward the upper and lower threads, a moving cam surface that rotates in synchronization with the lower shaft and moves the movable blade of the thread cutting means, and a stop cam surface for stopping the lower shaft And a driving means for engaging the cam follower of the thread cutting means with the thread trimming cam. When sewing with the sewing machine is finished, the driving means is driven when the sewing needle is raised, and the thread trimming cam is moved. Engage the cam surface with the cam follower of the thread cutting means , After cutting the upper and lower yarn by the movable blade and the fixed blade, to stop the lower shaft is brought into contact with the cam follower of the stop cam surface and the thread cutting means.
[0006]
In the sewing machine with an automatic thread trimmer according to claim 2, the stop cam surface of the thread trimmer cam is formed at a right angle or an acute angle with respect to the rotation direction of the thread trimmer cam.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to an electronically controlled lock stitch machine will be described with reference to the drawings.
[0008]
In FIG. 2, a leg column 2 is erected at the right end of the bed 1 having the needle plate 1 a, and an arm 3 is provided at the upper end of the leg 2. The arm portion 3 extends in the horizontal direction so as to face the bed portion 1, and a main shaft (not shown) is accommodated therein. The main shaft is connected to a sewing machine motor (not shown), and is driven to rotate by the sewing machine motor to drive the balance 17 and the needle bar 11.
[0009]
The solid line MB in FIG. 1 is a balance 17 using the rotational phase angle of the main shaft as a parameter, the solid line MA is a needle bar 11, and the solid line MC is a motion curve indicating the displacement of the movable blade 64c.
[0010]
As shown in FIGS. 3, 4, 5, and 6, the bed portion 1 accommodates a support plate 40. 5 is a front view, and FIG. 6 is a bottom view.
[0011]
The sewing machine body is provided with a thread trimming switch (not shown). When this thread trimming switch is operated, a thread trimming signal is output from a thread trimming signal generator (not shown), and the solenoid 50 shown in FIG. 8 constituting the driving means is energized. As a result, the adsorbing portion 46 a of the rotating member 46 is attracted to the core 50 a of the solenoid 50 against the spring force of the torsion spring 48, so that the rotating member 46 rotates in the arrow B direction around the pin 47. It has become. Then, the state shown in FIG. 8 is changed to the state shown in FIG.
[0012]
A lower shaft 51 is rotatably provided in the bed portion 1, a gear pulley (not shown) is fixed to the right end portion of the lower shaft 51, and a thread trimming cam 53 is fixed to the left end portion of the lower shaft 51, and The gear pulley is connected to a sewing motor (not shown) via a toothed belt (not shown). When the sewing motor is driven, the lower shaft 51 rotates via the toothed belt and the gear pulley, and the yarn is integrally formed with the lower shaft 51. The cutting cam 53 rotates.
[0013]
Further, as shown in FIG. 6, the support plate 40 is provided with a pin 59, and an urging lever 60 is rotatably attached to the pin 59. A torsion spring 59a is fitted to the outer peripheral surface of the pin 59, and the biasing lever 60 is biased in the direction of arrow K by the spring force of the torsion spring 59a. A pin 58 b is provided at the tip of the intermediate lever 58. A long hole 60a is formed on the proximal end side of the urging lever 60, and the pin 58b of the intermediate lever 58 is inserted into the long hole 60a.
[0014]
The support plate 40 is provided with pins 57 as shown in FIGS. An intermediate lever 58 is rotatably attached to the pin 57, and a spring 58c is fitted to the outer peripheral surface of the pin 57. The intermediate lever 58 is biased upward by the spring force of the spring 58c. The intermediate lever 58 is provided with a cam follower 58a. A cam groove is formed on the outer peripheral surface of the thread trimming cam 53, and a developed view of the cam groove is a first cam region 53a that is skewed with respect to an arrow N in the traveling direction of the thread trimming cam 53, as shown in FIG. A second cam region 53b to be a part, a third cam region 53c for restoring the cam follower 58a, and a fourth cam region 53d that is perpendicular to the traveling direction arrow N of the thread trimming cam 53. Therefore, the first cam region 53a, the second cam region 53b, and the third cam region 53c constitute a moving cam surface, and the fourth cam region 53d constitutes a stop cam surface.
[0015]
When the solenoid 50 is energized from the state of FIG. 8, the suction portion 46 a of the rotating member 46 is sucked by the core 50 a of the solenoid 50, and the rotating member 46 rotates in the arrow B direction, the pressing portion of the rotating member 46. The intermediate lever 58 is pressed by 46b. This is the state of FIG. As a result, the cam follower 58 a of the intermediate lever 58 is inserted into the cam groove of the thread trimming cam 53.
[0016]
As shown in FIG. 3, a resin member 62 made of a resin such as polyacetal is fixed to the upper surface of the support plate 40, and a sliding guide hole 63 is formed in the resin member 62 and the support plate 40. A sliding member 64 is placed on the upper surface of the resin member 62. Two pins 64 a and 64 b are fixed to the sliding member 64, and these two pins 64 a and 64 b are inserted into the sliding guide hole 63. The sliding member 64 is formed by connecting two plate members via a spacer, and the two pins 64a and 64b are guided by the sliding guide hole 63, whereby an arrow along the sliding guide hole 63 is provided. Move forward and backward in the M direction and in the opposite arrow M direction. Reference numeral 65 denotes a pressing member screwed to the support plate 40. The pressing member 65 is in contact with the upper surface of the sliding member 64 and prevents the sliding member 64 from being lifted when sliding.
[0017]
As shown in FIG. 6, one pin 64 a of the sliding member 64 is engaged with the long hole 60 b of the biasing lever 60. When the cam follower 58a of the intermediate lever 58 is inserted into the cam groove of the thread trimming cam 53, the cam follower 58a is pressed by the first cam region 53a of the thread trimming cam 53 of FIG. It rotates in the direction of arrow L about the center.
[0018]
Therefore, the rotational movement of the intermediate lever 58 is transmitted to the urging lever 60 via the pin 58 b of the intermediate lever 58, and the urging lever 60 rotates about the pin 59 in the counter arrow K direction. As a result, the sliding member 64 advances in the direction of arrow M along the sliding guide hole 63, and the tip end portion of the sliding member 64 enters the upper thread ring intersecting the lower thread. Yarn judgment is performed. When the cam follower 58a of the intermediate lever 58 comes into contact with the third cam region 53c from the second cam region 53b of the thread trimming cam 53, the cam follower 58a is pressed following the third cam region 53c of the thread trimming cam 53. 6, the intermediate lever 58 rotates in the counter arrow L direction around the pin 57.
[0019]
As shown in FIG. 4, a movable blade 64c is formed on the upper plate material constituting the sliding member 64, and a thread catching portion 64d is formed on the lower plate material. A fixed blade 66 is formed at the right end of the support plate 40.
[0020]
Therefore, the rotational movement of the intermediate lever 58 is transmitted to the urging lever 60 via the pin 58b of the intermediate lever 58, and the urging lever 60 rotates in the direction of the arrow K around the pin 59 with the help of the spring force of the torsion spring 59a. The sliding member 64 moves backward along the sliding guide hole 63 in the counter arrow M direction. As a result, both the upper and lower threads are captured by the thread capturing portion 64d of the sliding member 64, and the captured upper and lower threads are drawn toward the fixed blade 65, and the movable blade 64c and the fixed blade 66 of the sliding member 64 are brought together. Disconnected between.
[0021]
Next, the operation of the above configuration will be described. When the thread trimming switch is operated, the solenoid 50 is energized in the vicinity of a rotation phase angle of 180 ° in FIGS. 6, 7, and 8, and the suction portion 46 a of the rotating member 46 is attracted to the core 50 a of the solenoid 50. The rotating member 46 rotates in the arrow B direction around the pin 47 against the spring force of the torsion spring 48. Then, the intermediate lever 58 is pressed by the pressing portion 46 b of the rotating member 46, and the cam follower 58 a of the intermediate lever 58 is inserted into the cam groove of the thread trimming cam 53 against the spring force of the spring 58 c.
[0022]
When the cam follower 58a of the intermediate lever 58 comes into contact with the first cam region 53a of the thread trimming cam 53, the cam follower 58a is pressed following the first cam region 53a of the thread trimming cam 53 as the lower shaft 51 rotates. The lever 58 rotates in the arrow L direction. Then, first, the rotational movement of the intermediate lever 58 in the arrow L direction is transmitted to the urging lever 60 via the pin 58b of the intermediate lever 58, and the urging lever 60 rotates in the counter arrow K direction around the pin 59. Move. Next, the rotational movement of the urging lever 60 in the direction opposite to the arrow K is transmitted to the sliding member 64 through the pin 64a, and the sliding member 64 moves along the sliding guide hole 63 as shown in FIG. Advancing in the direction of arrow M, the tip of the sliding member 64 enters the upper thread ring intersecting the lower thread, and the upper and lower threads are separated. This state corresponds to the inclined portion α in the solid line MC of FIG.
[0023]
Next, when the cam follower 58a of the intermediate lever 58 comes into contact with the third cam region 53c from the second cam region 53b of the thread trimming cam 53, the cam follower 58a is pressed following the third cam region 53c. For this reason, in FIG. 6, the intermediate lever 58 rotates about the pin 57 in the counter arrow L direction, the urging lever 60 rotates about the pin 59 in the arrow K direction, and the sliding member 64 slides. It retreats in the opposite arrow M direction along the guide hole 63.
[0024]
Further, when the sliding member 64 moves back in the opposite arrow M direction along the sliding guide hole 63, the upper and lower yarns are captured by the yarn capturing portion 64d of the sliding member 64 and are drawn toward the fixed blade 66 side. This state corresponds to the inclined portion β in the solid line MC of FIG.
[0025]
The upper and lower yarns captured by the yarn trapping portion 64d are cut between the movable blade 64c and the fixed blade 66. In FIG. 1, the yarn cutting point in the present embodiment is indicated by C.
[0026]
After the upper and lower yarns are cut, a sewing machine motor stop signal is output, and the sewing machine motor is cut off. In FIG. 1, the sewing machine motor stop signal output point in the present embodiment is indicated by D.
[0027]
At this time, the cam follower 58a of the intermediate lever 58 abuts on the fourth cam region 53d formed perpendicular to the traveling direction arrow N of the thread trimming cam 53, so that the rotation of the thread trimming cam 53 is stopped by the cam follower 58a. The lower shaft 51 also stops. Thereafter, the solenoid 50 is de-energized, and the cam follower 58a is moved upward from the thread trimming cam 53 by the spring force of the spring 58c, and the thread trimming operation is completed.
[0028]
Therefore, without providing the clutch mechanism, the thread trimming operation ends when the sewing needle 11a and the needle plate 20 are sufficiently separated from each other. As a result, there is a problem that the configuration is complicated and the cost is increased. Without such a problem, it is possible to solve the problem that the sewing needle 11a cannot penetrate the work cloth and remove the work cloth.
[0029]
Also, in the past, efforts were made to improve the stopping accuracy of the sewing machine motor by devising the control circuit of the sewing machine motor, and to reduce deviation and variation between the output phase of the sewing machine motor stop signal and the stopping phase of the lower shaft. In the present invention, since the cam follower 58a contacts the thread trimming cam 53 and the lower shaft 51 stops, the stop phase is constant, and the sliding member 64 is also surely moved backward.
[0030]
In this embodiment, the stop cam surface of the thread trimming cam 53 is configured at right angles to the traveling direction arrow N. However, as shown in FIG. You may comprise at an acute angle with respect to the arrow N. FIG.
[0031]
【The invention's effect】
As is apparent from the above description, the sewing machine with an automatic thread trimming device of the present invention has the following excellent effects.
[0032]
That is, according to the sewing machine with an automatic thread trimmer according to claim 1, the driving means is driven when the sewing needle is raised, the movable cam surface of the thread trimmer cam is engaged with the thread cutting means, and the sewing thread is fed by the movable blade and the fixed blade. After the cutting, it is controlled so that the lower cam is stopped by bringing the stop cam surface of the thread trimming cam into contact with the thread cutting means, so that the thread is kept in a state where the sewing needle and the needle plate are sufficiently separated without providing a clutch mechanism. The cutting operation ends, and as a result, the configuration is simplified, the cost can be suppressed, and the problem that the work cloth cannot be removed can be solved.
[0033]
Furthermore, according to the sewing machine with an automatic thread trimmer according to claim 2, since the stop cam surface of the thread trimmer cam is formed at a right angle or an acute angle with respect to the rotation direction of the thread trimmer cam, the lower shaft is surely stopped. can do.
[Brief description of the drawings]
FIG. 1 is a timing chart showing an operation of a sewing machine according to an embodiment of the present invention.
FIG. 2 is a perspective view showing an appearance of the sewing machine.
FIG. 3 is a top view showing a configuration of the sewing machine thread trimming device.
FIG. 4 is an operation explanatory diagram in a state in which a movable blade of the thread trimming device is moved.
FIG. 5 is a front view showing the configuration of the thread trimming device.
FIG. 6 is a bottom view showing the configuration of the thread trimming device.
FIG. 7 is an enlarged front view showing a solenoid of the thread trimming device.
FIG. 8 is an operation explanatory diagram in a state where the solenoid is activated.
FIG. 9 is a development view showing a thread trimming cam of the thread trimming device.
FIG. 10 is a development view showing another thread trimming cam of the thread trimming device.
[Explanation of symbols]
1a Needle plate 11a Sewing needle 17 Balance 26 Upper thread 50 Solenoid 51 Lower shaft 53 Thread trimmer cam 58 Intermediate lever 58a Cam follower 64c Movable blade 66 Fixed blade

Claims (2)

By operating the balance in synchronization with the vertical movement of the sewing needle, the upper thread ring intersecting with the lower thread is tightened to form a contact point between the upper and lower threads on the work cloth, and the upper and lower threads are moved in synchronization with the operation of the balance. In sewing machine with automatic thread trimming device to cut,
A thread cutting means having a movable blade and a fixed blade located below the needle plate and moving the movable blade toward both the upper and lower threads;
A thread trimming cam that rotates in synchronization with the lower shaft and has a moving cam surface for moving the movable blade of the thread cutting means, and a stop cam surface for stopping the lower shaft;
Drive means for engaging a cam follower of the yarn cutting means with the yarn cutting cam;
When sewing by the sewing machine is finished, the driving means is driven when the sewing needle is raised, the movable cam surface of the thread trimming cam is engaged with the cam follower of the thread cutting means, and the upper and lower edges are moved by the movable blade and the fixed blade. A sewing machine with an automatic thread trimming device characterized in that, after cutting both yarns, the lower cam is stopped by bringing the stop cam surface into contact with the cam follower of the yarn cutting means. 2. The sewing machine with an automatic thread trimmer according to claim 1, wherein the stop cam surface of the thread trimmer cam is formed at a right angle or an acute angle with respect to the rotation direction of the thread trimmer cam.

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