JPS5845675Y2 - Sewing machine bobbin thread tension detection device - Google Patents

Description

[Detailed description of the invention] This invention detects the tension of the lower thread of the sewing machine that is paid out from the bobbin case, and adjusts the tension of the upper thread during sewing according to the type of fabric and sewing thread, its thickness, etc. This invention relates to a bobbin thread tension detection device for a sewing machine that sets a bobbin thread tension that matches the sewing machine and obtains a good edge fit.

Conventionally, any sewing machine has an upper thread adjuster attached to the sewing machine body to adjust the tension, but the lower thread tension can be adjusted by tightening the screw to which the tension spring is attached to the bobbin case. This is generally done by experience or feeling, and no device has been found to detect the tension.

However, some devices are equipped with a single bobbin thread tension measuring device, that is, one that holds the bobbin and bobbin case in one hand and pulls out the bobbin thread wound on the bobbin with the other hand. However, since it is a manual operation, the pulling speed changes and is not constant, and the measuring pointer oscillates significantly, making it difficult to accurately detect the bobbin thread tension, and also requires the use of both hands. Therefore, it was impossible to adjust the tension while making measurements.

The present invention solves these defects by adding a tension detection device to the bobbin thread winding mechanism of the sewing machine body, and detects the tension of the bobbin thread wound on the bobbin via the bobbin thread winding shaft driven by the upper shaft. The aim was to find good and beautiful relatives that could be detected numerically and also adjusted.

Embodiments of the present invention will be described below with reference to the drawings.

1 is a sewing machine frame (head), 2 is an upper shaft, and 3 is a hand wheel mounted on the upper shaft.

Reference numeral 4 denotes a line winding shaft on which a deceleration worm gear 5 is fixedly mounted, and 6 is an intermediate shaft on which a worm 7 and a timing gear 8 that mesh with the worm gear 5 are fixedly arranged. It is loosely fitted and pivotally supported in the appropriate positions 1a and lb of the frame.

Reference numeral 9 denotes a timing gear fixed to the upper shaft, through which the rotation of the upper shaft is transmitted via the timing belt 10 to the line winding shaft 4 via the intermediate shaft 6, although this transmission path is not shown. , can be shut off at any time regardless of the rotation of the upper shaft.

In the case of this embodiment, the rotation speed of the upper shaft 2 is approximately 90 degrees r, p, m, and the rotation speed of the line winding shaft 4 is approximately 1/90 degrees r, p, m.
30, that is, approximately 3Q r, p, m.

Reference numeral 11 denotes a bobbin winding shaft (see Figures 3 and 4), which has a positioning collar part 11a in the middle, and a guide member 1 for inserting and removing the bobbin.
A long hole 11b that engages and slides with the second pin 12a, and a groove 11C that fixes a bobbin case 14 that accommodates the pin 13 at one end.

The other end of the bobbin winding shaft 11 is loosely fitted into the machine frame 1a, and a ring plate 16 on which a rubber ring 15 is fitted is tightened.

Reference numeral 17 denotes a push spring for the guide member 12, which is stretched between the machine frame 1a and the guide member 12 and always urges the guide member in the right direction as viewed in the figure. A case is shown in which the bobbin 13 is pressed against the push spring 17, and FIG. 4 shows a state in which the bobbin 13 is taken out.

Reference numeral 18 denotes a pointer plate rotatably supported on a cylinder 19 fixed to the machine frame 1a concentrically with the bobbin winding shaft 11, and is provided with a recess 18a for receiving the corner 14a of the bobbin case 14. , the tip portion forms a pointer 18b.

18C is a roller shaft fixed to the pointer plate 18 located approximately midway between the recess 18a and the pointer 18b;
A roller 19 having a circumference a is restrained from moving in the axial direction and is rotatably inserted.

Further, reference numeral 20 denotes a spring having one end fixed to the pointer plate 18 and the other end fixed to an appropriate position of the machine frame. Then, the pointer 18b is located at the stopper part 21 at the right end of the display board 21.
It is brought into contact with a.

A display board 21 is attached to the machine frame 1a at a position opposite to the movement range of a pointer 18b, which will be described later.The display board 21 indicates the type of thread used for the border.

Thickness etc. are marked appropriately.

Although it is outside the scope of the present invention, the mechanism by which the bobbin thread is wound around the bobbin as shown in the fourth figure will be briefly explained.
As shown in Figure (5-A), the rubber ring 15 that is tightened to the bobbin winding shaft 11 is in contact with the loose arm 23 that is rotatably supported by a lever 22 that is loosely fitted on the same axis. , said lever 2
2 is pulled in one direction by a spring 24 whose one end is fixed to the machine frame, and is brought into pressure contact with a rotary wheel 25 (releasably driven) driven from the upper shaft 2 by a structure not shown.

Therefore, the movement of the rotary wheel 25 is transferred to the rubber ring 15 via the floating force 23.
, and the bobbin 13 also rotates in the same manner.

Reference numeral 26 denotes a bobbin presser in the bobbin winding mechanism, which is composed of a presser plate 26a and a notch 26b, and the notch 26b is in contact with the first knot portion 22a of the lever 22 when winding of the bobbin thread begins. , due to the increase in the amount of thread wound on the bobbin 13, the
As shown in figure -B, the presser plate 26a is rotated in the direction.

Therefore, the notch 26b rotates at the same time and moves to the second joint portion 22b of the lever 22, so that the free arm 23 is moved to the rotating wheel 2.
The state shown in Fig. 5-C in which the thread is released from 5 is reached, and the thread winding operation is stopped.

The structure of the device of the present invention is as described above, and its operation will be described below.First, the bobbin 13 with the bobbin thread wound thereon is placed in the bobbin case 14, and as shown in the third figure, the bobbin case 14 is placed at the corner 14a of the bobbin case. Insert and set the bobbin case 14 onto the bobbin winding shaft 11 at a position where the recess 18a of the pointer plate and the recess 18a of the pointer plate match.

Next, the end of the bobbin thread wound around the bobbin is entangled and fixed in the tip split groove 4a of the thread winding shaft 4, thereby completing preparations for detecting the tension of the bobbin thread.

Next, after checking the interlocking relationship between the thread winding shaft 4 and the upper shaft 2, when the upper shaft is rotated, the bobbin thread 22 wound on the bobbin 13
is wound around the thread winding shaft 4 against the clamping force of the tension spring 14b of the bobbin case 14, and the pointer plate 18 is rotated at its corner 14a as the bobbin case rotates (counterclockwise in the figure). are rotated in the same direction against the spring 20.

The rotation of the pointer plate 18 stops when the clamping force of the tension spring 14b of the bobbin case and the elastic force of the spring 20 become equal.
The marked value on the display board 21 where b is located indicates the lower thread tension.

10g with No. 30 cotton thread, 2 with No. 50 cotton thread, and No. 30 silk thread.
The spring 20 is set so that the force is 0 g.

As described above, in the device of the present invention, the bobbin winding shaft 1
The bobbin case 14 with the bobbin 13 housed therein is attached to the bobbin case 14, and the bobbin thread is wound onto the thread winding shaft 4, which is driven by the upper shaft, so that the tension can be detected. There is no unevenness in the force, and the withdrawal speed is also uniform, allowing for accurate pointing movement.

Furthermore, since this series of operations is all mechanically and automatically performed after the preparation for tension detection is completed, it is possible to adjust the tension spring of the bobbin case even during this movement.

In addition, in the present invention, these devices are housed in the bobbin thread winding device unique to the sewing machine, so that they are integrated with the sewing machine and have great practical effects as a new bobbin thread tension detecting device.

[Brief explanation of drawings]

Figure 1 is a plan view of the sewing machine head equipped with the device of the present invention.
-A is a side view thereof, FIG. 2 is an explanatory diagram of the drive of the bobbin thread winding shaft of the device of the present invention, and FIG. 3 is a central sectional view of the bobbin thread tension detection mechanism.
-A figure is its side view, 4th and 4-A, 4-B figures are the 3rd side view.
Figure 5 (5-A, 5-B)
, 5-C> is an explanatory diagram of winding the bobbin thread. 2...Upper shaft, 4...Thread winding shaft, 10
...Timing belt, 11...Bobbin winding shaft, 13...Bobbin, 14...Bobbin case, 18...Pointer plate, 19...
- Roller, 20...Spring, 21...Display board, 22...Lever, 26...Bobbin holder, 27...Bobbin thread .

Claims (1)

[Scope of utility model registration request] A bobbin winding shaft 11 is pivotally supported on the machine frame 1 by the upper shaft 2 of the sewing machine.
and the thread winding shaft 4, and the lower thread winding shaft 11 has a
A bobbin case 14 housing a bobbin 13 with a bobbin thread is mounted on a shaft so that it can be inserted freely, and the bobbin winding shaft 1 is mounted on the machine frame 1.
A pointer plate 18 that can rotate concentrically with the pointer plate 1;
A display plate 21 is provided at a position opposite to the pointer 18b of 8, and the rotation of the thread winding shaft 4 resists the elastic force of the spring 20 that locks the pointer plate to the pointer plate 18. The sewing machine is housed in a sewing machine bobbin winding device which detects the tension of the bobbin thread through cooperation between the pointer 18b and the display plate 21, and is integrally installed in the machine frame 1. A bobbin thread tension detection device for sewing machines.