JPS5816388Y2 - sewing machine balance device - Google Patents

Description

[Detailed explanation of the idea] This invention relates to a balance device for sewing machines.

Conventionally, as the main shaft of the sewing machine rotates, the thread take-up body is swung by a thread take-up crank fixed to the end of the main shaft.
The needle bar is moved up and down via a needle bar crank rod, and in conjunction with the rotation of the main shaft of the sewing machine, a full rotary hook serving as a thread ring catcher is rotated twice per rotation of the main shaft, and supports the needle bar. In a lockstitch sewing machine in which the needle bar support frame is swung left and right to form zigzag stitches, such as an industrial lockstitch buttonhole sewing machine, the sewing machine main shaft and full-rotation hook are connected to each other as shown in Figure 1. and are each rotated clockwise when viewed from the head side of the sewing machine arm.

However, in this sewing machine, as shown in FIG.
As shown in Figure 3, when the needle bar is raised to the left or right position of the swing amplitude, the amount of rise of the needle and the amount of encounter between the needle and the hook (distance from the tip of the hook to the thread hole of the needle) Because of the large difference in the oscillation amplitude of the needle bar, it has been impossible to form uniform stitches without skipped stitches or the like with a predetermined amount of contact at each position of the swinging amplitude of the needle bar.

For example, as shown in FIG. 1, if the radius R1 of the rotation locus of the crank pin provided on the balance crank is 17.5 mm,
The radius R2 of the rotation locus of the tip of the sword in the pot is 20.9 mm,
The distance L1 between the main shaft of the sewing machine and the rotary axis of the hook is 196.5.
mm, the distance L2 between the pivot axes at both the upper and lower ends of the needle bar crank rod is 45 mm, and the distance L3 from the lower end pivot axis of the needle bar crank rod to the upper end of the needle thread hole is 117.6 m.
m, and when the needle reaches its lowest point with the needle bar at the center of its swing amplitude, the distance 11 from the upper end of the thread hole of the needle to the rotation locus of the tip is as shown in Figure 1a. It becomes 4.5mm,
From the state shown in Figure 1 a, the main shaft of the sewing machine moves in the direction of the arrow at an angle θ.
1 (approximately 26.38 degrees), the needle is raised 2.5 mm and the encounter amount 12 is 2 mm, as shown in Figure 1, and the hook is set so that the tip of the hook meets the needle. On a sewing machine that has been installed, the needle bar can be moved three times to the left or right as shown in Figures 2 and 3.
Table 1 shows the amount of rise and encounter of the needle when the needle is swung at an amplitude of 13 mm.

In other words, when the needle bar is raised at the left position of the swing amplitude as shown in Fig. 2, the needle is moved 3 mm to the left compared to when it is raised at the center position, so the sewing machine main shaft is rotated by the angle 01 at the angle θ2 (the angle obtained by subtracting α/2 from θl: approximately 22.
At the point when the hook has been rotated by 26°), the tip of the hook will meet the needle, and the amount of rise of the needle will be 1.12 mm smaller than when the needle bar is raised at the center position shown in Figure 1. At the same time, the amount of contact 12 increases by Q, 83 mm.

Note that the above α indicates the angle formed by the line segment connecting the hook center to the tip of the hook with respect to the line connecting the center of the sewing machine main shaft and the hook center, and this α° indicates the angle that the sewing machine main shaft rotates half that amount, α/2°.

Also, as shown in Figure 3, when the needle bar is raised at the right position of the swing amplitude, the needle is moved 3 mm to the right compared to when it is raised at the center position, so the main axis of the sewing machine When the hook is rotated by an angle θ3 (angle θ1 plus α/2: approximately 30651') beyond the angle θ1, the tip of the hook meets the needle, and the center point shown in Fig. 1 is reached. Compared to when the needle bar is raised at the position, the amount of rise of the needle increases by 1.42 mm, and the amount of encounter 12 decreases by 1.71 mm.

Therefore, at the left or right position of the swing amplitude, the needle thread loop is not captured well by the tip of the shuttle, resulting in skipped stitches and the like.

In order to eliminate such defects, as shown in Figures 4 and 5, the main shaft of the sewing machine to which the take-up lever crank is fixed should be rotated counterclockwise, opposite to the rotating direction of the hook, when viewed from the head side of the sewing machine arm. can also be considered.

With this configuration, the rotating direction of the main shaft of the sewing machine and the hook are reversed, so the needle bar is moved 3 to the left as shown in Figure 4.
When the sewing machine is raised while being swung at an amplitude of 13 mm, the needle bar crank rod upper end pivot shaft rotates counterclockwise as shown in Fig. 2 due to counterclockwise rotation of the main shaft of the sewing machine. The angle β1 made by the needle bar crank rod with respect to a straight line hanging from the center is larger than the angle β2 in Fig. 2, and the needle bar is therefore raised quickly, causing the main shaft of the sewing machine to move at an angle θ2 (θl-α). /2) The amount of rise of the needle at the time of rotation becomes large.

Furthermore, when the needle bar is swung to the right with an amplitude 13 of 3 mm and raised as shown in Fig. 5, the counterclockwise rotation of the main shaft of the sewing machine causes the clockwise rotation as shown in Fig. 3. In comparison, the angle β1 shown in FIG. 5 is smaller than the angle β2 in FIG. The amount of rise of the needle at the point in time becomes smaller.

The amount of rise and the amount of encounter 12 of the needle when the left or right position of the needle bar rises are determined under the same conditions as in Figs. 1 to 3 by changing only the direction of rotation of the main shaft of the sewing machine. Table 2
Therefore, there is almost no difference in the amount of rise and encounter of the needle when the needle bar is raised to the left or right position and when it is raised to the center position.

However, when the main shaft of the sewing machine is configured to rotate counterclockwise when viewed from the head side of the sewing machine arm as described above, the tip extends to the right of the sewing machine arm as in conventional sewing machines. Even if the take-up lever arranged in this manner is simply connected to the take-up lever crank on the sewing machine spindle using a well-known crank mechanism, the take-up lever will not perform the prescribed take-up operation as the sewing machine spindle rotates. .

In order to avoid this, a configuration may be considered in which the take-up lever is arranged so that its tip extends to the left of the sewing machine arm, and the take-up take-up body and the take-up crank are connected by a well-known crank mechanism or the like. With this configuration, the thread insertion hole formed at the tip of the thread take-up body is located on the left side of the sewing machine arm, making it difficult for most right-handed users to thread the thread through the thread insertion hole. Become something.

This invention was made in view of the above points, and is configured so that the main shaft of the sewing machine has a take-up crank fixed to its tip and rotates counterclockwise when viewed from the take-up crank side.
In a sewing machine that can form uniform stitches without skipped stitches with almost the same amount of contact at each position of the needle bar's swing amplitude, the tip is located on the right side of the sewing machine arm when viewed from the take-up crank side of the sewing machine main shaft. To accurately operate a thread take-up body arranged so as to extend to the thread take-up body based on counterclockwise rotation of a thread take-up crank, and to easily perform threading work through a thread insertion hole of the thread take-up body. The purpose of the present invention is to provide a new scale device for a sewing machine that can perform the following steps.

Hereinafter, this invention will be explained in detail based on an embodiment of an industrial lockstitch buttonhole sewing machine shown in Figs. It consists of a bed section 1a, a pillar section 1b, and an arm section 1C.

Reference numeral 2 denotes a main shaft of the sewing machine rotatably supported within the arm portion 1C via a bearing metal 3, etc., and is driven by a drive source such as a motor to the head side of the arm portion 1C as shown by the arrow in FIG. It is designed to rotate counterclockwise when viewed from above.

4 is a support pin whose one end is fitted and fixed to the upper end of the arm 1C on the head side; 5 is a support plate fixed to the front surface of the arm 1C with a screw 6; I support it.

Reference numeral 7 denotes a needle bar support frame whose upper end is swingably supported by a support pin 4 so that it can reciprocate in the left-right direction when viewed from the head side of the arm portion 1C, and a needle bar support frame 7 is swingably supported at its upper end by a support pin 4. A groove portion 7a extending in the vertical direction is formed.

Reference numeral 8 denotes an abutment plate attached to the front lower end of the needle bar support frame 7 with screws 9;
It is a guide plate that is fitted onto the front surface of the needle bar C and fixed with a screw 11, and its free end is joined to the abutment plate 8 to guide the swinging of the needle bar support frame 7.

Reference numeral 12 denotes a needle bar supported movably up and down at the rear of the needle bar support frame 7, and a needle bar holder 13 having a pin 13a is fixed to approximately the middle part thereof, and a needle 14 is attached to the lower end. has been done.

Reference numeral 15 designates an arm portion 15 extending below the sewing machine main shaft 2 and parallel to the main shaft through a bearing metal 16 or the like.
It is a swing shaft rotatably supported in C, and is rotated back and forth via a suitable zigzag movement generating mechanism (not shown) as the main shaft 2 of the sewing machine rotates.

17 is a swinging arm fixed to the front end of the swinging shaft 15,
A pin 17 a is protruded from the lower front surface of the needle bar support frame 7 and is loosely fitted into a sliding piece 18 having a substantially rectangular front face provided in the groove 7 a of the needle bar support frame 7. In accordance with the movement, the needle bar support frame 7 is swung in the left-right direction based on a set amplitude.

A take-up crank 19 is fixed to the front end of the main shaft 2 of the sewing machine (the end on the head side of the arm IC) with a screw 20, and on the front thereof there are two shaft parts 21 extending parallel to the main shaft 2 of the sewing machine. A crank pin 21 having portions a and 21 b is protruded and fixed by a screw 22.

Reference numeral 23 denotes a needle bar crank rod whose upper end is rotatably attached to the outer shaft portion 21a of the crank pin 21 by a countersunk head screw 24, and the needle bar holder 13 is attached to the lower end of the crank rod. A pin 13a is loosely fitted, and as the main shaft 20 of the sewing machine rotates counterclockwise, the needle bar 12 is reciprocated in the vertical direction in cooperation with the thread take-up crank 19 and the crank pin 21.

Reference numeral 25 denotes a support pin fixedly disposed within the arm portion 1C by a screw 26 at a position to the right of the sewing machine main shaft 2 when viewed from the take-up crank 19 side, and extends parallel to the sewing machine main shaft 2.

Reference numeral 27 denotes a balance support whose base end is rotatably supported by the support pin 25, and its free end extends to the left as shown in FIGS. 6 and 8.

28 is the balance support 27 with a pin 28a in the middle part.
a swing lever rotatably supported on a free end of the swing lever;
One end thereof extends downward and is rotatably connected to the inner shaft portion 21b of the crank pin 21, and the other end thereof extends to the left when viewed from the take-up crank 19 side of the sewing machine main shaft 2.

Reference numeral 29 denotes a support pin that is fitted and fixed to the upper part of the arm portion 1C with a screw 30 at a position to the left of the sewing machine main shaft 2 when viewed from the take-up crank 19 side, and extends parallel to the sewing machine main shaft 2. ing.

Reference numeral 31 denotes a balance body whose base end is swingably supported by the support pin 29, and as shown in FIGS. 6 and 8, its free end extends to the right and projects outward from the arm portion 1C. A thread insertion hole 31a is formed at its tip.

Reference numeral 32 designates one link rotatably connected to the proximal forked portion of the balance body 31 at one end by a pin 32 a, and the other end is connected to the swing lever 28 by a pin 32 b.
is rotatably connected to the other end.

Therefore, as the sewing machine main shaft 2 rotates counterclockwise, the swing lever 28 is swung up and down by the cooperation of the take-up crank 19, crank pin 21, and take-up support 27, and the take-up lever 28 is moved up and down via the link 32. The body 31 is swung.

Reference numeral 33 denotes a well-known fully rotary hook for zigzag sewing, which is attached to the front end of a hook drive shaft (not shown) extending parallel to the main shaft 2 of the sewing machine in the bed portion a of the sewing machine frame 1. It is made up of an outer hook 33b having a diameter of 10 mm, and an inner hook 33C whose rotation is restricted, and a bobbin case 34 containing a bobbin (not shown) can be attached thereto.

In this embodiment, the outer pot 33 of the pot 33 is
As the main shaft 2 of the sewing machine rotates, □ moves at twice the speed of the main shaft 2 of the sewing machine through an appropriate gear transmission mechanism (not shown) in the opposite direction to the main shaft (as shown by the arrow in Fig. 6). (clockwise as seen from the head side of arm part 1C)
It is designed to be rotated to

The operation of the sewing machine constructed as described above will now be described.

Now, in this sewing machine, when the main shaft 2 of the sewing machine is driven by, for example, depressing the starting pedal, the take-up crank 19 rotates as seen from the head side of the arm portion 1C of the sewing machine frame 1, as shown by the arrow in FIGS. Rotated clockwise.

Thereby, the crank pin 21. Needle bar crank rod 2
3 and the needle bar holder 13, the needle bar 12 is moved up and down.

Further, as the sewing machine main shaft 2 rotates, the swing shaft 15 is reciprocated, and the swing arm 17 swings. The frame 7 is swung left and right.

Therefore, the needle 14 attached to the lower end of the needle bar 12 is moved up and down while being oscillated at a predetermined amplitude.

On the other hand, as the balance crank 19 rotates counterclockwise, the swing lever 28 supported by the balance support 27 is swung via the crank pin 21, so that the balance body 31 is rotated via the link 32. It is swung up and down.

Further, as the main shaft 2 of the sewing machine rotates, the outer hook 33b of the hook 33 is rotated in a direction opposite to the take-up lever 19 when viewed from the head side of the arm portion 1C of the sewing machine frame 1, as shown by the arrow in FIG. is rotated clockwise.

Therefore, as shown in FIGS. 4 and 5, when the needle bar 12 is raised to the left or right position of the swing amplitude, and when it is raised to the center position, the needle 14 moves from the lowest point to the hook 33. sword tip 3
This means that there is almost no difference in the amount of rise until it meets 3'a and the amount of encounter at that meeting point (distance from the tip of the needle to the thread hole of the needle).

According to the configuration of this embodiment, as the needle 14 moves up and down and the hook 33 rotates, the hook thread amount curve of the needle thread as shown by A in FIG. 9 is shown, and the thread take-up body 31
As a result of the swinging, a thread take-up curve of the needle thread as shown by B in the same figure is obtained, and by the combined action of these, uniform stitches without skipped stitches etc. can be formed.

It should be noted that this invention is not limited to the configuration of the above-mentioned embodiments, and the configuration of each part can be arbitrarily changed without departing from the spirit of this invention.

As described in detail above, according to this invention, the main shaft of the sewing machine having a thread take-up crank fixed to its tip is configured to be rotated counterclockwise when viewed from the thread take-up crank side. Even if it is possible to form uniform stitches without skipped stitches with almost the same amount of stitching at the same position, the tip may not be the same as seen from the thread take-up crank side of the main shaft of the sewing machine based on the counterclockwise rotation of the thread take-up crank. To accurately operate a thread take-up body arranged so as to extend to the right, and to easily perform threading work through a thread insertion hole at the tip of the thread take-up body extending to the right of a sewing machine arm. It has the excellent effect of being able to

[Brief explanation of drawings]

Figures 1 to 3 are diagrams for explaining the amount of rise and encounter of the needle in accordance with the rotation of the sewing machine main shaft and hook in a conventional sewing machine, and Figures 4 and 5 are diagrams for explaining the rise of the needle in the sewing machine of this invention. Diagram for explaining quantity and encounter quantity, No. 6
The figure is a partial front view of a sewing machine embodying this idea, Figure 7 is a partial cross-sectional view taken along line 7-7 in Figure 6, and Figure 8 is a partial front view of a sewing machine embodying this invention.
FIG. 9, which is a partial cross-sectional view taken along line 8-8 in the figure, is a graph showing a hook thread amount curve and a thread take-up amount curve as the sewing machine main shaft rotates.

Claims (1)

[Scope of Claim for Utility Model Registration] A sewing machine main shaft rotatably supported on a sewing machine arm and having a thread take-up crank fixed to the end of the arm on the head side; The sewing machine is rotatable in the direction, and is supported at the base end on the arm at a position to the right of the sewing machine main shaft when viewed from the take-up crank side, and is freely rotatable around an axis parallel to the sewing machine main shaft. A balance support whose end extends to the left; a free end of the balance support rotatably supported at an intermediate portion, one end extending downward and rotatably connected to the balance crank; a swinging lever extending to the left when viewed from the take-up crank side of the sewing machine main shaft; and a rocking lever swingably supported by the arm at a base end at a left position relative to the sewing machine main shaft when seen from the take-up crank side; A thread take-up body whose free end extends to the right and protrudes outside the arm and has a thread insertion hole formed at its tip; A thread take-up device for a sewing machine, characterized in that a swing lever is provided with one link rotatably connected to the other end thereof.