JPH0739669A - Needle thread cutting device for embroidery sewing machine - Google Patents

Abstract

PURPOSE:To decrease the influence due to the elongation of a needle thread, to easily obtain an exact remaining amount of the needle thread, and to easily and widely change the remaining amount of the needle thread in accordance with the kind of the needle thread. CONSTITUTION:When a thread take-up lever 7 descends in a state that a needle 4 is stopped in a top dead center position, a needle thread hooking member 19 hooks a needle thread T between the needle 4 and a shuttle 13, and draws it closer to a desired position in the rear from the needle 4. After the operation of the needle thread hooking member 19, a needle thread inserting/holding member 21 inserts and holds the needle thread T between the thread take-up lever 7 and the needle 4. After the operation of the needle thread inserting/ holding member 21, a needle thread cutting member 27 cuts the needle thread T in the lower side of a throat plate 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a needle thread cutting device for embroidery sewing machines, and more particularly to a device for cutting a needle thread of a required length before a needle.

[0002]

2. Description of the Related Art Generally, in an embroidery sewing machine, the upper thread is cut when the color is changed or the sewing place is changed. In this case, the upper thread having a required length is formed before the needle. Need to be cut off leaving. When the remaining amount of the upper thread is too small, the yarn end of the upper thread easily comes out of the needle hole, and when the remaining amount of the upper thread is too large, the yarn end of the upper thread easily protrudes at the next sewing start position. As a conventional needle thread cutting device in consideration of this point, for example, Japanese Patent Laid-Open No. 61-15999.
The technique disclosed in Japanese Patent Publication No. 1 is known. With this conventional device, with the thread tension disc above the balance loosened, the thread clamp grasps the upper thread under the needle and pulls it toward the rear of the needle, then tightens the thread tension disc. A cutting device is configured to cut the upper thread below the needle plate.

However, according to this conventional device, since the yarn path from the tension disc to the thread catching device and the thread trimming device is very long, when pulling the upper thread, the upper thread is rubbed by frictional resistance of many thread guides including the balance. A considerable amount of elongation occurs,
Also, when the upper thread is cut, the upper thread is stretched as the thread cutting device moves. The amount of elongation of the upper thread changes depending on the type of the upper thread, so the amount of movement of the upper thread clamp must be adjusted each time the thread is replaced in order to obtain an accurate remaining amount of the upper thread. there were.

As another conventional needle thread cutting device, for example, a technique disclosed in Japanese Utility Model Publication No. 63-24872 is known. This conventional device uses a needle thread withdrawing device in which two fork-shaped hooks are provided on the tip of a lever, and the fork-shaped hooks are applied to the front upper notch of the bobbin case inserted in the hook. The upper thread is hooked on the fork-shaped hook portion and pulled out in a triangular loop shape connecting the hook portion and the cloth at three points, and one upper thread of this loop is cut.

However, according to this conventional device, the upper thread remaining thread is determined by the distance between the two fork-shaped hook portions.
When it is desired to change the remaining amount of the upper thread according to the type of the upper thread, it is necessary to prepare a plurality of upper thread drawing devices having different intervals between the hook portions and replace them, which is very troublesome. Also,
Since the distance between the two fork-shaped hooks is limited to the diameter of the shuttle or less, it is difficult to make the upper thread remaining thread large.

Therefore, an object of the present invention is to reduce the influence of the elongation of the upper thread, to easily obtain an accurate upper thread remaining amount, and to easily make the upper thread remaining amount according to the type of the upper thread. Another object of the present invention is to provide a new needle thread cutting device that can be changed over a wide range.

[0007]

In order to solve the above-mentioned problems, the needle thread cutting device of the present invention is arranged such that when the balance is lowered while the needle is stopped at the top dead center position, the needle thread is cut between the needle and the shuttle. The upper thread hooking member that hooks the upper thread to a desired position behind the needle, and the upper thread holding member that holds the upper thread between the balance and the needle after the operation of the upper thread hooking member. It is composed of an upper thread cutting member for cutting the upper thread on the lower side of the needle plate after the operation of the member.

[0008]

According to the needle thread cutting device of the present invention, the needle thread catching member operates while the thread balance is loosening the needle thread, so that the needle thread can be accurately pulled by the necessary amount without stretching. Further, when the upper thread cutting member cuts the upper thread, the upper thread holding member holds the upper thread near the needle, so that the elongation of the upper thread due to the movement of the upper thread cutting member is suppressed. Further, the remaining amount of the upper thread is determined by the amount of pulling by the upper thread catching member, and this amount of pulling can be easily and widely varied by adjusting the upper thread catching member.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 to 3, an arm 1 is provided on a main body frame (not shown) of the embroidery sewing machine,
A movable head 2 is supported on the arm 1 so as to be rotatable around a vertical axis. A plurality of needle bars 3 are arranged on the movable head 2 so as to be vertically movable, and a needle 4 and a cloth presser 5 are attached to each needle bar 3.

A guide bar 35 is attached to the arm 1 in parallel with the needle bar 3, and an elevating body 36 is mounted on the guide bar 35 so as to be vertically movable. An engaging element 37 is attached to the lifting body 36.
Is horizontally rotatably attached, and the engagement element 37 is engaged with the tip portion 3a of the needle bar 3 by an operating mechanism (not shown) as disclosed in, for example, Japanese Patent Laid-Open No. 4-292194. The position can be changed between a possible engagement position and a retracted position retracted from the engaged position. Further, the lifting body 36
The engaging element 37 is moved up and down based on the turning force of a main shaft (not shown) by an elevating mechanism (not shown) as disclosed in the publication, and when the engaging element 37 is at the engaging position, As shown in FIG. 1, the needle bar 3 is driven up and down, and when the engagement element 37 is in the retracted position, the needle bar 3 is not driven as shown in FIG.

A balance 7 is arranged above the needle 4 so as to be movable up and down, and an apron 8 is provided between the balance 7 and the needle 4. The embroidery frame 9 in which the work cloth W is stretched is arranged above the bed 10. The bed 10 is provided with a needle plate 12 having a needle insertion hole 11, and a shuttle 13 is installed below the needle plate 12. The upper thread T is supplied from the bobbin to the hook 13 through a thread tension tray (none of which is shown), the thread guide 14, the balance 7, the apron 8, the needle 4, the presser foot 5, and the needle insertion hole 11, and the upper thread T is supplied. Embroidery stitches are formed on the work cloth W by using the lower thread (not shown) fed from the shuttle 13.

A mounting plate 16 is fixed to the arm 1 in a slanting shape, and a stepping motor 17 is installed at its rear end. An upper thread catching member 19 is slidably supported on the upper surface of the mounting plate 16 via a guide 18, and a hook 20 is formed at the tip thereof. The upper thread catching member 19 is slid by the stepping motor 17 between the retracted position shown in FIG. 1 and the forward position shown in FIG. 2 and is stopped at the intermediate position shown in FIG. In the process of reaching the position, the upper thread T between the needle 4 and the shuttle 13 is hooked and pulled toward the rear of the needle 4. The intermediate position of the upper thread catching member 19 can be easily set in a wide range by controlling the rotation angle of the stepping motor 17.

The apron 8 is provided with the same number of needle thread holding members 21 as the needle bars 3. The upper thread catching member 21 includes a pair of catching pieces 22 which are opened and closed by a drive mechanism (not shown) using a solenoid as disclosed in, for example, Japanese Patent Laid-Open No. 60-173156. After the upper thread T is drawn, the clamping piece 22 is closed to clamp the upper thread T between the balance 7 and the needle 4.

A rotary solenoid 25 is installed on the lower surface of the bed 10 near the shuttle 13 via a bracket 24, and an upper thread cutting member 27 is connected to an output shaft 26 of the rotary solenoid 25. As shown in FIGS. 4 and 5, the needle thread cutting member 2
A knife 28 is fixed to the tip of 7, and the tip portion of the needle thread cutting member 27 and the knife 28 are arranged inside or outside the shuttle 13 as the needle thread cutting member 27 swings. When the thread cutting command is issued, the tip of the upper thread cutting member 27 and the knife 28 are arranged in the shuttle, and the tip of the upper thread cutting member 27 hooks the upper thread T as the shuttle 13 rotates to clamp the upper thread. After the operation of the member 21,
The knife 28 is moved to the outside of the shuttle, and the needle thread T is cut below the needle plate 12.

An upper thread gripping tool 30 is attached to the movable head 2 behind the needle bar 3. An opening 31 that is long in the arrangement direction of the needles 4 is formed in the lower portion of the needle thread gripper 30,
A large number of linear bodies 32 are densely arranged in this opening 31. Then, as shown in FIG. 1, the needle thread gripping tool 30 is configured such that when the needle thread catching member 19 slides from the intermediate position to the retracted position after the needle thread is cut, the cutting end portion of the needle thread T is caused by the linear body 32. Is elastically gripped and disengaged from the hook 20, and the yarn end can be held at a position apart from the work cloth W.

Next, the operation of the needle thread cutting device configured as described above will be described with reference to the time chart shown in FIG.

First, when the embroidery sewing with the specific needle 4 is completed, a thread cutting command is output from a control device (not shown) of the embroidery sewing machine, and the rotary solenoid 2 at the top dead center position of the needle 3.
5 is driven, and as shown in FIG. 6A, the upper thread cutting member 27
The scalpel 28 is placed inside the shuttle 13.

Then, after the needle 4 reciprocates once, as shown in FIGS. 2 and 6B, the engaging element 37 is disengaged from the tip portion 3a of the needle bar 3 to the retracted position, and the needle 4 is moved to the top dead center position. Be stopped.

In synchronization with the stop of the needle at the top dead center position,
The stepping motor 17 is rotated, and the upper thread catching member 19 is slid to the forward position through the opening 31 of the upper thread gripper 30 as shown in FIGS. 2 and 6C.

Next, the stepping motor 17 is reversely rotated while the balance 7 is descending, and as shown in FIGS. 3 and 6D,
The upper thread catching member 19 retracts from the forward position and stops at a preset intermediate position, and in this process, the hook 20 catches the upper thread T between the needle 4 and the shuttle 13 and the desired position behind the needle 4. Pull to a position. At this time, as shown in FIG. 6E, the balance 7
Is lowered to loosen the upper thread T, the upper thread catching member 19
Can accurately draw the necessary amount without stretching the upper thread T. Further, the upper thread remaining amount is the upper thread catching member 19
The pulling amount can be easily and widely varied by adjusting the intermediate position of the upper thread catching member 19.

When the upper thread catching member 19 stops at the intermediate position, as shown in FIG. 6F, the solenoid of the upper thread clamping member 21 is excited and the clamping piece 22 moves the upper thread T between the thread take-up 7 and the needle 4. Hold it.

Subsequently, as shown in FIG. 6G, when the balance 7 reaches the top dead center, as shown in FIGS. 1, 5 and 6H, the needle thread cutting member 27 is rotated in the reverse direction by the rotary solenoid 25. The needle thread T is cut below the needle plate 12 while the knife 28 is being moved and is moving to the outside of the shuttle 13. At this time,
Since the upper thread clamping member 21 clamps the upper thread T near the needle 4, the elongation of the upper thread T due to the rotation of the upper thread cutting member 27 can be suppressed.

In synchronism with this thread trimming, the stepping motor 17 is again rotated in the reverse direction, and the upper thread catching member 19 is slid from the intermediate position to the retracted position, as shown in FIG. 6I. The cut end of the linear body 32 of the upper thread gripping tool 30
And is held above the work cloth W.

Next, the engaging element 37 is attached to the tip portion 3a of the needle bar 3.
After returning to the engagement position with and, as shown in FIG. 6J, the needle 4 is driven up and down.

After that, the movable head 2 is turned, and FIG.
As shown in, the next needle 4 is indexed to the sewing position, the color is changed, and the next embroidery sewing is started using the needle thread T inserted through the needle 4. In this case, since the cut end portion of the preceding upper thread T is held above the work cloth W by the upper thread gripping tool 30, there is no possibility that the thread end will be entangled with the next upper thread T, and the embroidery stitches will be formed. It can be beautifully formed.

Then, the upper thread holding member 21 is released at the first stitch at the start of sewing, as shown in FIG. 6L.

The present invention is not limited to the configuration of the above-described embodiment, and may be carried out by arbitrarily changing the shape and configuration of each part without departing from the gist of the present invention, for example, as follows. It is possible. (1) The needle thread cutting member is composed of a pair of movable knives or a combination of a movable knives and a fixed knife. (2) The stepping motor 17 is replaced with a geared motor, a linear motor, a fluid pressure drive means, or the like.

[0028]

As described in detail above, according to the needle thread cutting device of the present invention, the influence of the elongation of the needle thread can be reduced, an accurate upper thread remaining amount can be easily obtained, and the upper thread can be easily obtained. There is an excellent effect that the remaining amount of the upper thread can be easily and widely varied according to the type of

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a needle thread cutting device of an embroidery sewing machine showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing another operating state of the needle thread cutting device.

FIG. 3 is a cross-sectional view showing still another operating state of the needle thread cutting device.

FIG. 4 is a plan view showing an upper thread cutting member of the same upper thread cutting device.

FIG. 5 is a plan view showing another operating state of the needle thread cutting member.

FIG. 6 is a time chart explaining the operation of the needle cutting device.

[Explanation of symbols]

4 needle 7 balance 12 needle plate 13 hook 19 upper thread catching member 21 upper thread holding member 27 upper thread cutting member T upper thread

Claims (1)

[Claims] 1. A needle thread hooking member for hooking an upper thread between a needle and a hook and pulling the needle thread to a desired position behind the needle when the balance is lowered while the needle is stopped at the top dead center position, An upper thread holding member for holding the upper thread between the balance and the needle after the operation of the upper thread catching member, and an upper thread cutting member for cutting the upper thread below the needle plate after the operation of the upper thread holding member. An upper thread cutting device for an embroidery sewing machine equipped with.