JPH0426490A - Needle thread cutting device of sewing machine - Google Patents

Abstract

PURPOSE:To efficiently execute cutting of an extra thick needle thread, etc., by closing a movable member of a needle thread inserting/holding mechanism as soon as it reaches an inserting/holding cutting position of a needle thread, inserting and holding the needle thread between the member and a fixed member, and also, allowing a cutting member for abutting on the needle thread together with a closing operation of the movable member to cut the needle thread by Joule heat caused by an electric conduction. CONSTITUTION:As a piston P of a cylinder expands, a fitting base 3 provided with aq needle thread inserting/holding mechanism 1 also starts movement to the left. When the piston P further expands, a detaining part 7a of the tip of a stopper 7 and one rise end part of an axis supporting part 1a1 of a movable member 1a are engaged to each other, therefore, the movable member 1a turns clockwise centering around a shaft around a shaft pin 1p, and therefore, after the apex of a cutting member 2 abuts on a needle thread 9, the movable member 1a insert and holds the needle thread 9 between the member and a fixed member 1b, and as soon as the apex of the cutting member abuts on the needle thread 9, the cutting member 2 is conducted electrically, and due to Joule heat generated in the apex, the needle thread 9 is cut between a cloth holder K and a work W.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] This invention relates to a needle thread cutting device that cuts a needle thread connected to a workpiece after a sewing operation is completed.

The present invention relates to an upper thread cutting device for a sewing machine that is particularly suitable when using a very thick thread with high strength.

[Prior Art] Currently, sewing machines are equipped with a thread cutting device that automatically cuts the thread after the sewing operation is completed. This thread trimming device is equipped with a plate-shaped fixed blade installed on the side of the 1M-long sewing path, and a movable blade that overlaps the upper surface of the fixed blade. It is generally known that the movable blade is moved forward to cross the lifting path to capture the thread, and then the captured thread is pulled out to the side by the backward motion of the movable blade and sheared between it and the fixed blade. ing.

[Problem to be invented or solved] However, in the above-mentioned conventional thread cutting device, the thread is sheared, so to speak, by the joining operation of the movable blade and the fixed blade.

The blades of the fixed blade and movable blade wear out, reducing sharpness.

This is especially noticeable when extremely thick or strong threads are used. For example, in recent years, when sewing air hacks that are attached to cars, threads that are extremely thick compared to those used for sewing clothes, etc. When a conventional thread cutting device is used to cut such threads, the fixed blade and movable blade deteriorate in a very short period of time and must be replaced with new ones frequently. In some cases, the thread was inserted between the fixed blade and the movable blade without being cut, resulting in poor cutting.

Focusing on these problems, the applicant first filed the
No. 139220 discloses a needle thread cutting device for a sewing machine that can obtain good cutting performance even for tough threads and extremely thick threads by means of thread cutting means using hot rays. Since the cutting means each require a separate drive source, the structure is complicated, and there are problems in that it is difficult to set the drive timing.

It is an object of the present invention to solve the above-mentioned problems and provide an upper thread cutting position that has a simple configuration and can be easily adjusted in timing.

[Structure of the invention] A needle thread cutting device for a sewing machine according to the present invention is a needle thread cutting device for a sewing machine.

It has a needle thread cutting means that pinches and cuts the needle thread between the U-shaped needle and the workpiece, and the needle thread cutting means is connected to a fixed member and a movable member that opens and closes the needle thread with respect to the fixed member and pinches the needle thread. a cutting member which is provided on a movable member and operates together to generate Joule heat due to energization when the needle thread is in contact with the needle thread; The movable member is integrally constructed with a drive means for moving the movable member to the cutting position and for driving the movable member to open and close.

[Function] According to the third aspect of the present invention, the sewing operation by the sewing machine is completed,
When the needle rises, the needle thread clamping mechanism is moved by the driving means from the original position to the needle thread clamping and cutting position, and when the movable member of the needle thread clamping mechanism, which is opened while moving, reaches the needle thread clamping and cutting position. At the same time, the movable member is closed and the needle thread is held between the movable member and the movable member, and the cutting member that comes into contact with the needle thread cuts the needle thread using Joule heat generated by the energization.

In this way, when the needle thread between the sewing needle and the workpiece is cut, the engaging member of the needle thread feeding means returns to its original position, and then the needle thread holding mechanism removes the cut needle thread M. It returns to its original position while holding the product side end, and holds the needle thread end until the start of the next sewing operation.

[Embodiments of the invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an external perspective view of needle thread cutting means A according to the present invention.

In the figure, reference numeral 1 denotes an upper thread clamping mechanism consisting of a movable member 1a and a fixed member 1b, both ends of which are joined facing each other.

The movable member 1a includes a longitudinal shaft support 1a2 having rising portions at both ends, and a base 1al extending from the shaft support 1a2.
The pivot support 1a2 can be rotated to the mounting h3 by the pivot pin 1p (can be opened and closed with respect to the fixed member 1b).
is supported by

The base portion 1al has a round-r shape in cross section so that as it is mounted away from the base 3, the base 1al is located below the base 3.

Moreover, the fixing member 1b is also almost the same as the base 1al! l
It has an i-plane shape, and one end thereof is fixed to the base 3.

2 is a cutting member fixed to the lower surface of the base 1al;
As shown in the figure, it has a U-shape, and its top slightly protrudes from the side edge of the base 1al to the lower surface of the side edge of the fixing member 1b.

The mounting table 3 is connected to the tip of the piston P of the cylinder S, and moves forward and backward in the direction of the arrow in accordance with the movement of the piston P.

4 is a fixed base attached to the end of the cylinder S, -
A locking spring 6 is fixed to one side end, and a stopper 7 is fixed to the other end.

Further, the locking portion 7a at the tip of the stopper 7 and the shaft support 1a
The rising end portion (upper side in the figure) of No. 2 constitutes a regulating means for setting the timing at which the movable member 1a closes.

The locking spring 6 is biased against one rising end (on the near side in the figure) of the shaft support 1a2 of the nf moving member 1a to hold it in a predetermined position.

Reference numeral 5 is attached to a pressing spring fixed to the base 3, which engages with the lower surface of the pivot support 1a2 and presses it upward to prevent the pivot support 1a2 from shifting.

The needle thread cutting means A constructed as described above is attached to the lower part of the sewing machine rad M, as shown in FIG.

In the figure, AI is a support plate for fixing the needle thread cutting means A to the sewing machine M, and A2 is a clamp fitting that elastically supports the end of the cylinder S in a rotatable manner.

Reference numeral C denotes needle thread feeding means, which is composed of an engaging member 8 and a cylinder 8a as a means for driving the engaging member 8 forward and backward. In which direction is the upper thread 9 between the needle N and needle N?
The yarn is bent and fed out from the yarn supply source side.

Furthermore, B is a guide means for guiding movement of the needle thread cutting means A between the original position and the cutting position, and is constituted by a guide plate IO having an inclined hole 10a.

An engager (not shown) of the upper thread clamping mechanism 1 is fitted into this inclined hole 10a, and the movement path of the upper thread clamping mechanism 1 due to the expansion and contraction of the cylinder S is regulated as shown by the arrow.

The operation of this embodiment will be explained with reference to FIGS. 2, 4, and 5 based on the above-described configuration.

2 and 4 are a side view and a plan view of the needle thread cutting means A in its original position with the needle thread clamping mechanism 1 in the closed state.

First, when sewing is completed, the cylinder 8a of the thread feeding means C puts the thread under tension between the engaging member 8 or the ejecting needle N and the object to be sewn.

Next, as the piston P of the cylinder S extends to the left in the direction of the arrow, the mounting base 3 equipped with the upper thread clamping mechanism 1 also begins to move to the left.

At this time, one rising end (lower side in the figure) of the shaft support 1a2 of the movable member 1a is engaged with the locking spring 6, so the movable member 1a moves counterclockwise around the shaft pin 1p. The movable member 1a in the upper thread clamping mechanism 1 is fixed when it comes into contact with the other rising end (upper side in the figure) of the shaft support 1a2 or the end 1bl of the fixed member ib. The member ib is opened with the upper thread 9 in between.

Looking at the operation during this time in Fig. 2, as the cylinder S expands, the upper thread cutting means A is guided by the guide means B from its original position and moves to the lower left in the figure. , the fixing member 1 is located below the presser foot K, with the upper thread 9 in between.
b and the movable member 1al are in an open state. (5th
(See figure) Then, in the state shown in Figure 5, the piston P
When extended, the locking portion 7a at the tip of the stopper 7
The movable member 1a engages with one (upper in the figure) rising end of the shaft support 1al of the movable member 1a.
It rotates clockwise around P, so that the apex of the cutting member 2 comes into contact with the needle thread 9, and then the movable member 1a or the needle thread 9 is held between the fixed member 1b and the cutting member 2. At the same time as the point In contacts the upper thread 9, the cutting member 2 is energized, and the upper thread 9 is cut between the presser foot K and the workpiece W due to the Joule heat generated at the apex.

Note that a preliminary timer is set so that this energization is started at the above-mentioned timing according to the operation timing of the air cylinder S.

Then, the operator can adjust the timing back or forth depending on the thickness of the thread, etc.

Thereafter, the needle thread clamping mechanism 1 which is in a state of clamping the N side end of the cut needle thread 9 moves to the position shown in FIG. Return to the original position shown.

During this time, with the exit of the upper thread clamping mechanism 1, the holding member 8 of the upper thread feeding means C also returns to its original position, and when the next sewing process is started, the upper thread end held by the upper thread clamping mechanism 1 is Needle N
It is removed by the action of

Thereafter, the above-mentioned operation is repeated.

In addition, in this embodiment, as shown in FIG. 3, the cutting member 2 has a very small vertex that comes into contact with the needle thread.
When energized, this part instantly becomes red hot and allows for quick cutting operations, but since it has a U-shape as a whole, it does not "sag" due to repeated contact with the upper thread. This does not occur and the durability is significantly improved.

[Effects of the Invention] As described above, the present invention has a structure in which the means having the functions of pinching and cutting the needle thread are integrated into one body, and the means are also driven by a single drive source, so that each function can be easily performed. In addition to being able to easily adjust the timing, we have created a durable needle thread cutting device with a small number of parts, which allows for efficient cutting of high-strength needle threads or extremely thick needle threads, and improves sewing quality. , sewing efficiency is improved.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view showing a needle thread cutting device according to an embodiment of the present invention, and FIG. 2 is a side view of a sewing machine equipped with a needle thread cutting device according to an embodiment of the present invention. Fig. 3 is a plan view of the cutting member, Fig. 4 is a plan view of the upper thread cutting means in which the upper thread clamping mechanism is in the closed state, and Fig. 5 is a plan view of the upper thread clamping mechanism changing from closed to open and then closed. It is a top view of the needle thread cutting means which shows a process. In the figure, needle thread cutting means guide means needle thread feeding means cylinder (driving means) a Movable member Needle thread clamping mechanism Fixed member Cutting member Applicant Shuuki Co., Ltd. Fig. 2

Claims (1)

[Scope of Claims] A needle thread cutting device for a sewing machine that cuts the needle thread from the sewing needle to the workpiece after the sewing operation is completed, the needle thread cutting device cutting the needle thread between the sewing needle and the workpiece by pinching the needle thread between the sewing needle and the workpiece. The upper thread cutting means is provided on the movable member and operates together with an upper thread clamping mechanism consisting of a fixed member and a movable member that opens and closes with respect to the fixed member and clamps the upper thread. a cutting member that generates Joule heat due to energization when in contact with the upper thread; and a driving means that moves the upper thread holding mechanism and the cutting member from their original positions to the upper thread cutting position and drives the movable member to open and close. An upper thread cutting device for a sewing machine, characterized in that the needle thread cutting device is integrally configured with the following.