JPS6025984B2 - Sewing machine needle stop position correction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a needle stop position correcting device for a sewing machine, and more particularly to a needle stop position correcting device after thread cutting in a sewing machine having a thread trimming mechanism.

2. Description of the Related Art Sewing machines that are equipped with an automatic thread cutting mechanism that automatically cuts an upper thread or lower thread sewn onto a workpiece cloth after a predetermined sewing process are well known.

The automatic thread trimming action is performed when the operator depresses the pedal or the like. However, in sewing machines with this type of thread trimming mechanism, the needle stop position after thread trimming is lower than the highest position, and when sewing thick fabrics, etc., the fabric material and the needle tip come into contact, causing the fabric to be cut. The problem arises that the sewing machine cannot be attached, which causes a significant decrease in the efficiency of the sewing process. In other words, the automatic thread trimming mechanism uses the rotation of the main shaft of the sewing machine after the needle lifts away from the workpiece cloth and reaches the highest position to perform thread trimming, so the needle position after thread trimming is at its original optimal stop. The position is lowered from that position. Figure 1 shows the height 3 of the needle bar and the main bottle relative to the phase angle of the sewing machine's main axis, that is, the upper axis, and the timing at which the thread trimming action is performed, and the needle twill to which the needle is fixed is shown by its height characteristic 100. As such, it takes a position that almost matches the rotational phase of the upper axis, and is at the top at a phase angle of 0 degrees of the upper axis. On the other hand, it is understood that the height characteristic of the main thread which tightens the upper thread is indicated by 200, and the highest position 201 is at a position that lags behind the characteristic 100 of the needle bar. As is well known, the thread cutting action is carried out by the movable knife selecting the threads to be cut after the needle moves up and coming out of the work cloth, and selectively cutting the predetermined threads by the shearing action with the fixed knife. be exposed. This thread cutting completion point is broken line 3
00, and the position of the needle at this thread trimming completion point 300 is significantly lower than the highest point Hm, and as a result, as mentioned above, it is difficult to attach thick cloth during the next sewing process. This has the disadvantage of causing a significant decrease in work efficiency, which is a major problem with automatic thread trimming sewing machines. The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide a needle stop position correction device for a sewing machine that can slightly raise the needle position to an ideal predetermined position after thread trimming is completed. be.

To achieve the above object, the present invention provides a sewing machine having an automatic thread trimming mechanism, including a return solenoid that is disposed near the upper shaft and is temporarily energized after thread trimming is completed, and a return solenoid that is connected to the return solenoid. It includes a return lever that is rotationally driven when the solenoid is energized, and a driven element that is connected and fixed to the upper shaft and can come into contact with the return lever, and the driven element is moved by a predetermined amount by the return lever when the return solenoid is energized after thread cutting is completed. The needle stop position is corrected upward by rotating the upper shaft within a small rotation angle.

Preferred embodiments of the present invention will be described below based on the drawings.

FIG. 2 shows a preferred embodiment of the needle stop position according to the present invention, in which a sewing machine arm 10' is supported and an upper shaft 12 passing through the arm is equipped with a flywheel 14 and a rotational phase as is well known. A detector 16 is provided. A toothed belt pulley 18 is firmly fixed to the upper shaft 12 by a set screw 20. and upper axis 1
2 is being connected and driven.

A feature of the present invention is that it has a return solenoid 24 for reversing the upper shaft from the stop position after thread trimming, and that the position of the upper shaft 12, that is, the needle stop position, is corrected by the excitation drive of the return solenoid 24. It is in.

The return solenoid 24 has an excitation coil 26 that is temporarily excited and driven each time the needle stops, and an armature 28, and a return lever 32 that is supported on a support shaft 30 at one end of the armature 28.
One end is pivoted. The aforementioned return solenoid 24
In order to receive the return force caused by the rotational force, the upper shaft 12 is provided with a follower, and the driven member in this embodiment is formed of a pusher pin 34 mounted on the side of the toothed belt pulley 18.

The other end of the return lever 32 is disposed near the rotation of the driven pin 34, and in the non-energized state of the return solenoid 24 in FIG. Normally, the return lever 32 and the pivoting pin 34 do not come into contact with each other. The embodiment of the present invention has the above configuration, and its operation will be explained below.

FIG. 4 shows the main structure of the above-mentioned embodiment. In the normal sewing state, the excitation coil 26 is in a non-excited state, so the return lever 32 is in the chain line position, and as mentioned above, the The end is in a state of being retracted from the rotation area of the driven pin 34.

Therefore, the upper ball 12 and the toothed belt pulley 18 can rotate in the direction of arrow A regardless of the correction device according to the present invention. When the automatic thread trimming operation is performed and the thread trimming is completed at the position indicated by 300 in FIG. 1, the upper shaft 12 also stops, and the driven pin 34 at that time is in the position shown by the solid line in FIG. 4.

After this thread trimming is completed, an exciting current is supplied to the exciting coils 26 of the return solenoids 2 and 4 in order to correct the needle stop position, and as a result, the armature 28 is attracted and moved by the coil 26, and as a result, the armature 28 is The supported return lever 32 also rotates in the direction of arrow B. The return lever 32 shown by the solid line shows a state in which the other end is in contact with the driven pin 34, and the return solenoid 24 further attracts the armature 28 from this state, so the driven pin 34 is returned to the normal position by the return lever 32 to the broken line position. It will be rotated in a direction opposite to the rotation direction A. As a result, as is clear from FIG. 1, the movement angle of the driven pin 34 from the thread trimming completion point 300 in the direction of arrow C in FIG. Then, the needle returns to the opposite direction and rises, and the corrected needle stop position 300 is obtained. Therefore, as is clear from FIG. 1, the needle height is corrected in the upward direction by h from the conventional height, and even after automatic thread trimming, the final needle stop position is changed according to the present invention. By this correction, even thick fabrics can be sufficiently attached to the position, and the efficiency of the sewing process can be significantly improved without requiring manual correction by the operator in the conventional device. In the embodiment, the driven pin 34 is raised on the side of the toothed belt pulley 18, but a flange separate from the toothed belt pulley 18 is provided on the upper shaft 12, and the driven pin 34 is fixed to the flange. It is also possible.

As described above, according to the present invention, it is possible to upwardly correct the needle stop position of a sewing machine with an automatic thread trimming mechanism, and it is possible to obtain a correction device that is particularly useful for industrial sewing machines.

[Brief explanation of the drawing]

Fig. 1 is a characteristic diagram showing the height characteristics of the needle comb and shaft pin with respect to the rotational phase of the main shaft of the sewing machine and the state of each part during thread trimming, and Fig. 2 shows a preferred embodiment of the needle stop position correction device according to the present invention. FIG. 3 is a cross-sectional view of the main part taken along the line m--m in FIG. 2, and FIG. 4 is an explanatory view of the main part for explaining the operation of the embodiment shown in FIGS. 2 and 3. The same part of the village in each figure is given the same code, 12 is on the upper axis, 18
24 is a return solenoid, 32 is a return lever, and 34 is a driven pin. Figure 2 Figure 3 Lacquer Figure 4

Claims (1)

[Claims] 1 (1) In a sewing machine having an automatic thread trimming mechanism,
a return solenoid disposed near the upper shaft and temporarily energized after thread trimming is completed; a return lever connected to the return solenoid and rotated when the solenoid is energized; and a return lever connected and fixed to the upper shaft and capable of contacting the return lever. a driven child;
A needle of a sewing machine characterized in that a driven element is moved by a predetermined amount by a return lever by energizing a return solenoid after thread trimming is completed, and the upper shaft is reversely rotated within a small rotation angle, thereby upwardly correcting the needle stop position. Stop position correction device. (2) A needle stop position correction device for a sewing machine, wherein the driven element is formed of a driven pin installed on the side of a belt pulley fixed to the upper shaft. .