JPS6345251Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention mainly relates to a lock stitch mechanism in a blind stitch sewing machine.

For example, regular blindstitch sewing machines use chain stitching, which has the disadvantage that if the final stitch frays, all the stitches will fray. By the way, in the past, to prevent needle breakage, the needle was stopped at the top dead center, the fabric was pulled forward, the thread was cut, and the sewing was completed when the thread was cut, and no special backstitching was performed. Ta.

However, with this method, when the fabric is stretched, the seam threads are pulled and the beautiful seams shrink, reducing the value of the product and causing the threads to fray.

For this reason, after cutting the thread, it is necessary to manually tie the end of the thread to make a knot, or at the end of sewing, operate the pedal to remove the presser foot from the throat plate. By separating them and reducing the amount of cloth fed, the stitches are sewn in close overlaps to prevent fraying. However, in the former case, work efficiency is low because it is done manually, and in the latter case, it is impossible to perform overlapping stitches in which the stitches are closely overlapped without stopping the sewing machine each time. There was a problem in that the sewing thread became loose as the feed amount decreased. Of course, in order to maintain proper thread tension when performing overlapping stitches, it is sufficient to stop the sewing machine and adjust the thread tension knob, but it is extremely troublesome to stop the sewing machine each time. ,
This is a cause that significantly impedes work efficiency.

This invention has a collar feed mechanism that raises the feed dog from the throat plate surface at the end of sewing, stops cloth feed, and performs overlap stitching, and a
The purpose of the present invention is to provide a tacking device that solves the above problem by providing a mechanism that applies a certain thread tension to the sewing thread, and that enables stable tacking without having to stop the sewing machine each time. That is.

Hereinafter, the present invention will be explained based on the drawings.

1 to 12 show an embodiment of this invention, in which reference numeral 1 is an upper shaft, and 2 and 3 are eccentric cams. These eccentric cams 2,
3 is a well-known device, and is configured to apply a swinging motion to the cloth feed table 4 in response to the rotation of the upper shaft 1. The cloth feed table 4 is supported by the above-mentioned upper shaft 1 on the base side, and is fixed with a screw 7 to a feed support pin 6 rotatably attached to the feed support crank 5 on the free end side.

On the other hand, a crankshaft of a slider crank 11 is rotatably fitted into a bearing bush 10 which is press-fitted into the frame body 8 and fixed with a screw 9, and as shown in FIGS. 5 and 6, A transmission pin 12 is rotatably fitted eccentrically to the axis of the crankshaft. And this transmission pin 12
is the feed support crank 5 as shown in FIG.
It is attached with screws 13. That is, the feed support crank 5 rotates with respect to the frame body 8 using the transmission pin 12 as a fulcrum, and swings the cloth feed table 4 to feed the cloth. In addition,
A feed dog 15 is fixed to the tip of the feed base 4 with a screw 14.

A rectangular slider 16 is slidably attached to the sliding groove of the slider crank 11, and a pin 1 to which one end of an operating lever 17 is fixed with a screw 18 is attached to the rectangular slider 16.
9, it is rotatably attached. The other end of the operating lever 17 is connected to the transmission shaft 22 by a screw 2.
3, it is rotatably attached. The transmission shaft 22 has one end supported by the frame body 8 and the other end rotatably attached to a shaft support plate 21 fixed to the frame body 8 with screws 20. .

On both sides of the shaft support plate 21 attached to the other end of the transmission shaft 22, there are operating levers 25 fixed to the transmission shaft 22 by screws 24, and control levers 25 fixed to the transmission shaft 22 by knock pins 26. An adjustment block 27 is provided to prevent the transmission shaft 22 from moving in the axial direction.

The free end of the operating lever 25 fixed to the transmission shaft 22 is provided with a mounting hole 25a for attaching a chain connected to a foot pedal, an air cylinder, a solenoid (not shown), or an operating rod (not shown). It is being Further, a bulge is formed at the end of the upper surface on the free end side of the operating lever 25, and a hole 25b is provided in the bulge. A tension coil spring 28 engaged with a pin 29 supported by the frame body 8 is provided in the hole 25b so as to bias the operating lever 25 in the opposite direction of the arrow O shown in FIG.

Moreover, approximately in the center of this operating lever 25, there is a
A protrusion 25d having a substantially elliptical elongated hole 25c is formed, and a stop pin 30 fixed to the frame body 8 is inserted into the elongated hole 25c. That is, as shown in Figure 1,
The rotation angle of the transmission shaft 22 when the free end of the operating lever 25 is pushed down in the direction of arrow O is the same as that of the elongated hole 25.
It is regulated by the length of c. Therefore, the elongated hole 25
c is set to a length that allows the slider crank 11 to rotate by θ ₁ +θ ₂ . Note that the rotation angle θ ₁ +θ ₂ of the slider crank 11 is determined by the tooth surface 1 of the feed dog 15 fixed to the cloth feed table 4, as described later.
5a is set to swing above the throat plate surface line P-P'.

The adjustment block 27, which is formed of a thick plate with an elliptical planar shape on both sides, has an adjustment screw 3 fitted with coil springs 33 and 34 to prevent loosening on both sides.
1 and 32 are screwed together and passed through. This adjustment screw 3
A stop plate 35 is fixed to the frame body 8 at the tips of the screws 1 and 32, which abut the respective screw ends.

On the other hand, in the thread passage, when the feed dog 15 is in the empty feeding state due to the rotation of the transmission shaft 22, there is a thread tightener that applies greater resistance to the thread in conjunction with the rotation of the transmission shaft 22. A mechanism 47 is provided. That is, a thread tightening lever 36 is fixed to the transmission shaft 22 by a screw 37 approximately in the middle between the operating lever 17 attached to the transmission shaft 22 and the shaft support plate 21 . A push rod 38 inserted into the frame body 8 is provided on the upper surface of the arm portion 36a of the thread tightening lever 36.
One end of the is abutted so as to be movable in the axial direction.

The other end of the push rod 38 is connected to a tension rod 3 which is screwed and fixed to the frame body 8, as shown in FIG.
The push rod 3 is inserted through the center hole of 9, and the push rod 3
8 is in contact with a spring receiver plate 40 that is inserted into the shaft portion 39a of the tension core rod 39 so as to be movable in the axial direction. The shaft portion 39a of the tone core rod 39 includes:
The thread pressing plates 41, 42 and the spiral spring 43 are inserted through the thread presser so as to be freely movable in the axial direction, and a tension nut 44 for adjusting the compressive force of the spiral spring 43 is screwed together. Note that the push rod 38 includes
A collar 45 that adjusts the movement range of the shaft is attached to a screw 46.
It is fixed by.

Next, the operation of the present invention will be explained.

First, when the upper shaft 1 is rotated, the cloth feed table 4 swings about the transmission pin 12 via the eccentric cams 2 and 3.

In this case, in the normal cloth feeding state, the feed dog 15 attached to the tip of the cloth feed table 4 draws a circulation locus A indicated by a broken line as shown in FIG. Since the linear movement portion of passes below the throat plate surface line P-P', the fabric is fed from left to right. In this state, the position of the transmission pin 12, which is the fulcrum of the swinging movement of the cloth feed table 4, is at the fifth position.
As shown in the figure, the slider crank 11 is displaced by an amount B, and as shown in FIG. 7, the slider crank 11 is tilted downward by θ ₁ with respect to the crankshaft.

On the other hand, if you want to tack stitch, use the operation lever 2.
5. Apply force in the direction of arrow O. This work can be done without stopping the sewing machine. At this time, the transmission shaft 22 rotates clockwise in FIG. Rotate in the stop direction by ₁ + θ ₂ . This angle change of the slider crank 11 also causes the position of the transmission pin 12, which is mounted eccentrically from the axis of the crankshaft, to change by θ ₁ +θ ₂ . The angle change of θ ₁ +θ ₂ of the transmission pin 12 causes the transmission pin 12 to rise by B+C (FIGS. 5 and 6), so the feed support crank 5 to which the transmission pin 12 is attached , and the cloth feed table 4 connected to the feed support crank 5 by a feed support pin 6 also rises by B+C in the direction of arrows Q and R around the eccentric crank 3.

In this case, the lower side of the circulation locus A of the tooth surface 15a of the feed dog 15, that is, the linear movement portion is located at the throat plate surface P-
Since it passes above the P' line, the throat plate surface P-
It is possible to tack stitches below the P' line without feeding the fabric held between the presser feet (not shown). In other words, since it is possible to perform overlapping stitches,
The sewing threads do not come undone easily.

When returning to the normal cloth feeding state from tacking, the force applied to the operating lever 25 is released, and the operating lever 25 is pulled by the coil spring 28 in the direction opposite to the arrow O shown in FIG. It is stretched back into place. Therefore, the cloth feed table 4, which had been raised, descends and starts a normal cloth feed movement.

Next, the operation of the thread tightening mechanism of the present invention will be explained.

In the normal cloth feeding state, the spring catcher 40 is pushed up via the push rod 38 to ensure that the compressive force of the spiral spring 43 does not apply resistance to the sewing thread passing between the thread pressers 41 and 42. Hold. That is, the sewing thread is only subjected to a load due to the weight of the upper thread presser plate 41.

On the other hand, when tacking is performed without feeding the cloth, force may be applied to the operating lever 25 in the direction of arrow O shown in FIG. Then, the transmission shaft 22 rotates clockwise, so the push rod 38 descends, and the spring receiver 40 comes into contact with the upper thread presser 41.
The compressive force of the spiral spring 43
By applying a load to the sewing thread passing between the
By applying resistance to the sewing thread, it is possible to perform tacking stitches without thread loosening.

The above operations are performed without stopping the sewing machine, so there is no need to stop the sewing machine and adjust the thread tension knob every time the sewing machine is sewn, which is the conventional method, making the sewing process easier and more efficient. It has the advantage of being good. Further, the resistance given to the sewing thread by the spiral spring 43 of the thread tightening mechanism can be set to a desired value by moving the tension round nut 44 up and down in advance.

Incidentally, FIG. 12 shows the state of the threads on the back side of the fabric sewn by the tacking device based on the present invention.

Next, another embodiment of the present invention will be described.

Regarding the collar feed mechanism of the above-mentioned embodiment, the mechanism using the operating lever 17 and the slider crank 11 was explained, but the end portion of the transmission shaft 22 (the first
The transmission pin 12 may be fixed eccentrically from the axis of the transmission shaft 22 to the left side in the figure. In this case, since the transmission pin 12 rises according to the rotation angle of the operating lever 25, the cloth feed table 4 also rises.

Further, when the actuation lever 17 is used as the collar feed mechanism, the arm portion 36a of the thread tightening lever 36 for moving the push rod 38 up and down may be formed on the opposite side of the pin 19 attached to the actuation lever 17. good.
In this case, since the operating lever 17 and the arm portion 36a of the thread tightening lever 36 are integrally formed, there is no need to provide the thread tightening lever 36 again.

On the other hand, regarding the thread tightening mechanism, instead of providing the spiral spring 43 as described above, a solenoid linked to the vertical movement of the operating lever 25 may be used as a means for applying resistance to the sewing thread. Although the above explanation is about a blind stitch sewing machine, it goes without saying that the invention can be applied to other sewing machines as well.

As mentioned above, this invention is equipped with a blank stitching mechanism that operates the control lever to raise the feed dog from the throat plate surface, stops the fabric feed, and performs overlap stitching, so it is possible to sew without stopping the sewing machine. It is possible to perform finely overlapping stitches and prevent threads from fraying due to overlapping stitches. Further, since a thread tightening mechanism is provided that can apply a predetermined resistance to the sewing thread without stopping the sewing machine, overlapping stitching can be performed with complete thread tightening. Therefore, the tacking device of this invention is capable of complete tacking without stopping the sewing machine, and has excellent practical effects such as dramatically improving work efficiency compared to conventional sewing machines.

[Brief explanation of the drawing]

Figures 1 to 11 show one embodiment of this invention. Figure 1 is a three-dimensional perspective view showing the operation section of the tacking mechanism and the feed dog raising mechanism, and Figure 2 is a scooping view of the same mechanism. Plan view of the built-in sewing machine, Part 3
The figure is a front view of Fig. 2, Fig. 4 is a side view showing the main parts of the feed bar, Figs. FIG. 11 is a side view showing the thread holding device of the tacking mechanism, and FIG. 12 is an external view showing an example of sewing according to this invention. 1... Upper shaft, 2, 3... Eccentric cam, 4... Cloth feed table, 5... Feed support crank, 11... Slider crank, 12... Transmission pin, 15... Feed dog, 22... Transmission Shaft, 47... Thread tightening mechanism.

Claims (1)

[Scope of utility model registration request] A cloth feed table with a feed dog at its free end is attached with its base end fitted into an eccentric cam on the upper shaft, and its middle portion pivoted to a feed table support crank that rotates around a transmission pin. A crank is attached to the transmission pin to move the transmission pin up and down by the rotation of the transmission shaft, and when the feed dog is in the empty feeding state by the rotation of the transmission shaft, the thread is connected to the thread passage. A tacking device for a sewing machine, comprising a thread tightening mechanism that applies greater resistance to the thread in conjunction with rotation of a transmission shaft.