JPH0386195A - Thread cutter for sewing machine - Google Patents

Abstract

PURPOSE:To utilize a thread cutter while prolong the life and further to cut a thick thread as well by making the thread in a meandering state by the forward motion of a pair of cutter elements, unfastening the thread 5 in the meandering state in the process of this backward motion and cutting the thread by the blades of the respective cutter elements. CONSTITUTION:After sewing is finished, a driving lever 24 is moved forward and respective cutter elements 11 and 12 is respectively moved forward in arrow directions. Then the both cutter elements 11 and 12 are overlapped. In such a case, a lower thread 42 is pulled out from a bobbin 4 and made in the meandering state by back parts 11b and 12b of the respective cutter elements 11 and 12. Next, the driving lever 24 is moved backward and the respective cutter elements 11 and 12 are also respectively moved backward. Then, by this backward motion of the respective cutter elements 11 and 12, the lower thread 42 pulled out from the bobbin 4 is set in the unfastened state. The backward motion of the driving lever 24 is further advanced and the backward motion of the respective cutter elements 11 and 12 is further advanced. The respective cutter elements 11 and 12 are, then, overlapped and with the coincidence of blades 11a and 12a, the lower thread 42 is cut. In such the case, with the forward motion of the respective cutter elements 11 and 12, the coincident point of the blades 11a and 12a is moved from the root sides of the respective blades to the tip sides.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thread cutting device for cutting a lower thread or an upper thread in a sewing machine.

[Conventional technology]

Under the throat plate, there is a fixed side cutter element disposed at a side position avoiding the position below the needle hole where the needle descends, and a fixed side cutter element that passes through the position below the needle hole and reaches the fixed side cutter element. For example, there is a thread cutting device in which the movable cutter element is provided with a recess for catching the thread and a blade is provided at the bottom of the recess. In this thread cutting device disclosed in Japanese Patent Publication No. 56-106692, as the movable cutter element moves, the thread caught in the recess faces the fixed cutter element in a taut state; In this state, the cutter is cut by the bottom blade and the blade of the fixed cutter element.

[Invention tries to solve! 11! II) In this conventional thread cutting device of a sewing machine, the thread is caught in the recess and is in a tensioned state, so the connection between one part of the blade at the bottom of the recess and one part of the blade of the fixed side force element is caught in between. Therefore, there is a problem in that the load on the one part of the blade that cuts the thread is heavy, and wear progresses rapidly, shortening the service life. In particular, when cutting thick threads, the wear of the blade progresses significantly, so in practice, there is a problem that it cannot be used for cutting such thick threads.

The present invention has been made in view of the above points, and an object thereof is to provide a thread cutting device for a sewing machine that can be used for a long life and can also cut thick threads. .

[Means to solve problems]

In order to achieve the above object, the present invention takes the measures described in the claims, and its effects are as follows.

[Effect]

The pair of cutter elements are reciprocated from their respective ready positions to the operative position while pulling the thread by their respective backs. This forward movement causes the thread to form a meandering pattern.The pair of zero-order cutter elements moves back from the operating position to the ready position. In the process of this backward motion, the meandering thread becomes slack, and the loosened thread is cut by the blade of each cutter element. When cutting, the loose thread is cut while moving in the longitudinal direction of the blade.

〔Example〕

The drawings showing the embodiments of the present application will be described below.

In FIG. 1, numerals 1 to 9 indicate the constituent members of a well-known multi-spindle sewing machine (for example, the same as that shown in Japanese Patent Application Laid-Open No. 60-173156), in which 1 is a bend, and 2 is a throat plate. , 3 is a shaft for driving the hook, 4 is the hook, 5 is an arm disposed above the bed 1, 6 is a holder attached to the arm 5 so as to be horizontally rotatable, 7 is up and down with respect to the holder 6 A freely movable needle bar, 7° is a thread take-up, 8 is a needle, and 9 is a presser foot. Reference numeral 10 indicates a thread cutting device provided under the throat plate 2.

Next, the thread cutting device 10 will be explained in detail based on FIG. 2.3. Reference numerals 11 and 12 denote a pair of cutter elements, which are arranged on both sides of the line 2' where the thread is expected to pass through the needle hole 2a as shown in FIG. 2 (as shown in FIGS. 5A and 5B).
The thread 42 passing through the needle hole 2a is provided with
The preparation position shown in Figures (A) and (B) and Figure 8 (A)
) and the operating position shown in (B). lla and 12a are the respective cutter elements 11 and 12 described above.
This blade is provided on the edge opposite to the line 2' where the thread is expected to pass. llb, 12b each cutter element 1
The mutual positional relationship between the two cutter elements 11.12, which shows the back of the cutter element 1.12, is as shown in FIGS. 10(A), (B) and FIG. The blades 11a, 12a of each cutter element 11.12 are in an overlapping position to enable thread cutting, and the blades 11a of each cutter element IL12.

The longitudinal direction of 12a is as shown in the above figure.
The blades 11a and 12a of both cutter elements are oriented so that they intersect with each other during the above-mentioned superposition and are in a state similar to the blades of scissors. 14
is a wave washer, which applies a biasing force to the cutter element 12 to press it against the cutter element 11, and improves the mutual rubbing of the blades of both cutter elements.

15.16 indicates the driven piece attached to each cutter element.
Next, 21 indicates a drive mechanism in the thread cutting device 10.
Reference numeral 2 denotes a base frame of the drive mechanism, also called a mounting base, which is fixed to the bend l. Reference numeral 23 denotes a drive shaft rotatably mounted on the base frame 22, and a drive lever 24 is fixed to the upper end. The drive lever 24 has a retaining hole 2 exemplified as a drive part.
5, into which the driven pieces 15 and 16 are loosely fitted.

27 is a transmission lever attached to the lower end of the drive shaft 23, and 28 is a drive device for swinging the transmission lever 27 in the direction of the arrow. For example, a solenoid is used (an air or hydraulic cylinder may also be used).

Next, 31 shows an upper thread distribution mechanism, and 32 is a mounting frame for this mechanism, which is fixed to the bed 1. 33 is the mounting frame 3
2, for example, a rotary solenoid is used in which the drive shaft 33a rotates back and forth. Reference numeral 34 denotes an upper thread hanging piece, which is formed in a forked shape, and the base part is connected to the drive shaft 33a using a mounting bracket 35, so that it can be moved in and out of the hook 4.

Next, cutting of the lower thread and upper thread by the thread cutting device 10 will be explained based on the time chart of FIG. 4 and the operation diagrams of FIGS. 5 to 21. In Figure 5.14, (A)
is a plan view, (B) is a longitudinal cross-sectional view of the cloth, throat plate, and thread cutting device cut away at position B-8 in Figure 5 (A), and (C) is a position C-C in Figure 5 (A). FIG. 2 is a longitudinal cross-sectional view of the cloth, throat plate, and thread cutting device in FIG. 8th ~ 1O11
(A) and (B) in Figure 2 and ( in Figure 13)
B) and (C) are the same drawings as in the case of FIG. 5 above, respectively. 6.7, If, and 16 to 21 are all plan views. Further, FIGS. 5 to 21 show the states at each point in time indicated by symbols 1 to 2 in FIG. 4, respectively.

First, cutting of the bobbin thread 42 will be explained based on FIGS. 4 to 12. In the process (a) in Fig. 4, as is well known, the needle 8
moves up and down, the hook 4 rotates, and the cloth 40 is moved laterally by the cloth feed device (cloth drive frame) 40a shown in FIG.
Sewing and embroidery on cloth 40 using upper thread 41 and lower thread 42 are performed in a well-known manner. At this time, the cutter elements 11.12 in the thread cutting device 10 are as shown in FIGS. 5(A) and 5(B).
, (C).

Next, when the above sewing is finished and the point in Figure 4 (b) is reached,
The operation of the needle 8 and the shuttle 4 is stopped, while the cutter elements 11, 12 are operated by the drive mechanism 21 as follows. First, when the drive lever 24 moves forward as shown by the arrow in FIG.
The respective cutter elements 11.12 move forward in the direction of the arrows, and both cutter elements 11.12 overlap as shown in FIG.

In this case the bobbin thread 42 is attached to the back 11 of each cutter element 11.12.
b and 12b, it is pulled out from the pot 4 as shown in the figure. As the forward movement of each cutter element progresses further, Fig. 8 (^”)
, (B), and the bobbin thread 42 becomes in a meandering state as shown in FIG. Force 7 elements 11.1
2 also begin to move back in the directions indicated by the arrows. Due to the backward movement of each cutter element 11 and 12, the bobbin thread 42 pulled out from the hook 4 becomes loose as shown in FIGS. 9(A) and 9(B).

The return movement of the drive lever 24 further advances and each cutter element 11
, 12 further progresses, each cutter element 11, 12 overlaps, as shown in FIGS. 10(A) and 11, and the blade 1
1a and 12a match. Such blades 11a, 12a
As a result of the matching, the bobbin thread 42 is caught between the blades 11a and 12a and cut as shown in FIG. 10CB). In this case, as shown in FIGS. 10(A) and 11, the blade 11a moves forward as each cutter element 11.12 moves forward.

The matching point 12a moves from the base side to the front side of each column. Therefore, even if the bobbin thread 42 is thick and difficult to cut, the portion of the bobbin thread 42 sandwiched between the blades 11a and 12a will be at the matching point as shown in FIGS. 10(A) to 11. As it moves, it moves while being sandwiched between the rows 11a and 12a and rubbing against them. Therefore, as the bobbin thread 42 moves along the blades 11a and 12a, it is gradually cut from the edge side of the bobbin thread 42 in the thickness direction by these blades 11a and 12a.

In this way, even if the bobbin thread 42 is thick and difficult to cut, it can be cut reliably. After the bobbin thread 42 is cut as described above, each cutter element 11° 12
After going through the states shown in Figures 2 (A) and (B), it changes to Figure 5 (A).
), the state returns to the state shown in (B).

Next, cutting of the upper thread 41 will be explained based on FIG. 4 and FIGS. 13 to 21.

First, the drive device 33 in the needle thread sorting mechanism 31 is activated, and the needle thread hanging piece 34 enters the hook 4 (see FIGS. 13(B) and (C) for the entering state). The operations of the hook 4 and the needle 8 are restarted, and the process shown in FIG. 4(c) is performed. During this process, as shown in Figure 13 (B
), the needle 8 through which the upper thread 41 is threaded enters the hook 4 as shown in (C). As is well known, the needle thread 41 is hooked on the tip of the hook 4 and goes around the hook 4, thereby forming a loop as well known. Eventually needle 8
When the sewing machine passes the top dead center and the thread take-up lever 7° rises to the upper limit position, reaching the point shown in FIG. In this state, Fig. 14(A)
~ As shown in (C), the loop 41d of the needle thread 41
is caught on the needle thread hook 34. After this state is reached, the thread cutting device 10 switches to the 15th to 2nd
As shown in Fig. 1, the operation is exactly the same as that for cutting the bobbin thread 42, and the needle thread 41a on the side of the needle thread 41 located below the throat plate 2 that is connected to the cloth 40 is cut. do. After the needle thread 41 is cut as described above, the needle thread hanging piece 34
will be evacuated outside.

The operations of the needle, hook, and thread cutting device as described above are performed in conjunction with each other using, for example, a well-known sequence control technique.

Next, FIG. 22 showing a different example of some operation modes will be described. In the above embodiment, at the time shown in FIG. 15, only the needle thread 41a on the side of the needle thread loop 41d on the lower side of the needle plate 2 that is connected to the cloth is removed by the cutter element 11.
12, and prevent the upper thread 41b on the side connected to the needle from being caught by the cutter element.
The locus of passage of the cutter elements 11, 12 is prevented from protruding to the right of the lower position of the needle hole 2a in FIG. 15. For this reason, when cutting the bobbin thread, there is a possibility that an accident may occur in which the back portions 11b, 12b of the cutter element 11.12 fail to capture the bobbin thread 42 at the time shown in FIG. If there is such a possibility, the above-mentioned Figure 5 (C
) After the point shown in FIG. 22, the cloth 40 is moved slightly to the left with respect to the throat plate 2 as shown in FIG.
It is preferable to place the lower thread 42 at a position along the side wall near the base of the cutter element.By doing so, the possibility of failure to capture the bobbin thread 42 can be minimized.

Next, FIG. 23 shows a different embodiment of the present application.

This Fig. 23 is Fig. 8 (^
), the engagement hole 25e of the drive lever 24e has a wide part 2 in a part of the engagement hole 25e.
5a is formed, and even if the drive lever 24e is rotated by the same angle as in the previous embodiment, the cutter element l
ie is designed to operate with a small amplitude, as is clear from the comparison with FIG. 8(A). By doing so, the bobbin thread 42e can be cut in a state where the length of the portion remaining connected to the cloth is shortened.

It should be noted that parts that are considered to have the same or equivalent structure as those in the previous figure in terms of function are given the same reference numerals as in the previous figure with the letter e, and redundant explanations are omitted.

〔Effect of the invention〕

As described above, in the present invention, when cutting the thread 42, due to the forward movement of both cutter elements, the thread on the above-mentioned expected passage line is bent in a meandering shape by the backs 11b and 12b of each cutter element 11.12. , by the double movement of both cutter elements 11 and 12, the blades IFa and 12a are cut in a state in which the bent thread is loosened.
The thread 42 is cut by the blade 11.
It has the feature that it can be cut while relatively moving in the longitudinal direction of a and 12a (shape M similar to cutting with a kitchen knife). This has the effect of easily cutting not only thin threads but also thick threads.Furthermore, since the long section of the blade is used, there is less wear on each part of the blade, so even thick threads such as those mentioned above Even when used for cutting thread, it has the effect of providing a long service life.

[Brief explanation of drawings]

The drawings show an embodiment of the present application, and FIG. 1 is a vertical sectional view of the main parts of an embroidery sewing machine, FIG. 2 is a partially cutaway perspective view showing a thread cutting device installed in the bed of the sewing machine, and FIG. An exploded perspective view of the thread cutting device, FIG. 4 is a time chart, FIGS. 5 to 21 are operation explanatory diagrams, FIG. 22 is a diagram showing a different example of a part of the operation mode, and FIG. 23 is a different embodiment. A plan view showing. 2... Throat plate, 2a... Needle hole, 4. 12... Cutter element, 40... Cloth, 41, 42...
・Lower thread. - Hook, 11° - Needle thread, Fig. 2 Fig. 3 Fig. 5 Fig. 5 (A) Fig. (0 Fig. R Fig. (E3) Fig. Fig. (A) Fig. A) Figure (8) Figure 10 (A) Figure 10 (B) Figure 1 Figure 2 (A) Figure 12 (8) Figure 22 Figure 23 Figure 2e

Claims (1)

[Claims] A sewing machine thread having a pair of cutter elements disposed between a throat plate having a needle hole and a hook disposed below the needle hole, respectively on both sides of a line through which the thread is expected to pass through the needle hole. In the cutting device, each of the cutter elements has a blade at an edge opposite to the expected line of passage of the thread, and each of the cutter elements has a reciprocating motion between a ready position and an operating position. In addition, the mutual positional relationship between both cutter elements is such that the blades of each cutter element overlap to enable cutting of the thread in the process of each backward movement, and furthermore, The longitudinal direction of the blades is oriented so that the blades of both cutter elements intersect with each other during the above-mentioned superposition, and by the forward movement of both cutter elements, the yarn on the above-mentioned scheduled passing line is directed to the back of each cutter element. 1. A thread cutting device for a sewing machine, characterized in that the thread is bent in a meandering manner by the blade, and the bent thread is cut by the blade in a slack state by the backward movement of both cutter elements.