JPH0215237B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cloth presser device for pressing a work cloth in an automatic sewing machine, and particularly to an intermediate presser device.

[Conventional technology]

The intermediate presser foot of this type of automatic sewing machine automatically sews while holding the sewing workpiece between the fabric holding plates and moving it in any direction according to the sewing information stored in the memory element. In order to smoothly feed the cloth, sewing is performed with the height of the lowest point (bottom dead center) of the intermediate presser set at a height that does not interfere with cloth feeding.

[Problem that the invention seeks to solve]

FIG. 10 shows an example of the lift curves of the needle and the intermediate presser. The horizontal axis represents time t, and the vertical axis represents the needle (tip) N and the lift height L of the intermediate presser _P0 from the needle plate height O as the origin. As shown in the figure, after the bottom dead center t ₁ of the needle tip N, after time T ₁ , the intermediate presser P ₀ reaches its bottom dead center at time t ₂ , so that both curves N and P ₀ substantially form a sine curve. It is constructed to look like a painting. Point A at time _t2 is the threading timing to form a loop of the bobbin thread.

However, it takes a certain amount of time to form the above loop, the needle N is in the upward stroke from the bottom dead center, and the height of the bottom dead center of the intermediate presser is such that it does not interfere with cloth feeding for the reasons mentioned above. The height l is set to ₀ .

Therefore, the fabric is lifted upward by the amount of penetration of the needle N, which causes skipped stitches and poor thread tightness. In particular, when the threading timing is changed depending on the sewing conditions, the timing with the intermediate presser changes, the bottom dead center position of the intermediate presser _P0 shifts, and the height of the intermediate presser when threading, _l0, becomes higher. As a result, the amount of fabric lifted increases, which tends to cause skipped stitches and poor thread tightness. The above phenomenon occurs when the bottom dead center of the intermediate presser that presses the workpiece cloth is at time t ₂
This is due to the fact that the loop formation time is not considered.

The present invention has been made in view of the problems of the conventional examples as described above, and aims to provide an intermediate presser mechanism for an automatic sewing machine that does not cause skipped stitches or poor thread tightening as in the conventional examples. There is.

[Means for solving problems]

Therefore, in the present invention, the curve P in FIG.
As shown in , a mechanism converts the swing motion of the intermediate presser shaft into vertical movement of the intermediate presser so that the intermediate presser is held at the bottom dead center position for a predetermined period after the needle reaches the bottom dead center. The above object is achieved by configuring the device to have idle movement means.

[Effect]

With the above configuration, it is possible to prevent skipped stitches and poor thread tightening in the automatic sewing machine.

〔Example〕

The present invention will be explained below based on examples.

FIG. 1 is a perspective view of essential parts of an embodiment of an intermediate presser according to the present invention, and FIGS. 2 to 4 are enlarged fragmentary views of each part of FIG. 1.

〔composition〕

In Figure 1, F is the sewing machine frame (machine frame),
A is the main shaft (upper shaft), N is the needle, and P is the intermediate presser.
When the eccentric cam 1 fixed to the main shaft A rotates with the rotation of the main shaft A, the connecting rod 2 loosely fitted to the eccentric cam 1 and the pin shaft 3 at the tip end of the eccentric cam 1 rotate.
The intermediate presser shaft 5 is adjusted by the adjusting arm 4 having a long hole 4a.
oscillate. An L-shaped link 7 and a link 8 are attached to the arm 5a at the tip of the intermediate presser shaft 5 via a link 6, respectively, and the link 8 is connected to an intermediate presser rod holder 9 to hold the intermediate presser rod 10. The fixed intermediate presser rod holder 9 is caused to reciprocate up and down with a predetermined stroke.

The intermediate presser P is fixed to the lower end of the intermediate presser rod 10, and performs vertical reciprocating motion together with the intermediate presser P.

The vertical movement of the intermediate presser P can be adjusted by moving the pin shaft 3 along the elongated hole 4a of the adjusting arm 4.

As described above, when the intermediate presser P reaches the lowest point (bottom dead center) of the vertical movement stroke, the intermediate presser P is moved so that there is a slight clearance l ₀ from above the throat plate (not shown). It is adjusted and fixed by operating the adjustment screw 9a of the rod holder 9.

When the intermediate presser bar holder 9 is lowered, it comes into contact with a stopper 15a of a presser foot lifting lever base 15 fixed to the sewing machine frame F and stops (see FIG. 4, which will be described later).

On the other hand, at the L-shaped corner of the L-shaped link 7, there is a deformed link 1, as shown in the enlarged broken perspective view in FIGS.
2 is pivotally connected by a pin 7a, and a pin shaft 12a is pivotally supported at the center corner of the deformable link 12 to a boss erected from the sewing machine frame F, and one end of the deformable link 12 is fixed to the sewing machine frame F. It is biased by a tension coil spring 13 to rotate around the pin axis 12a.

A stopper 14 is adjustably screwed into an internally threaded portion (not shown) embedded in the sewing machine frame F, facing toward the contact portion 12b (FIGS. 2 and 3) adjacent to the spring attachment end.

As described above, the arm 5a, the link 6, the L-shaped link 7, the link 8, the deformable link 12, and the stopper 14 constitute a motion conversion mechanism for vertical reciprocating motion. In addition, FIGS. 2 and 3 show the stopper 1.
4 shows a state in which the contact portion 12b is in contact with and apart from the contact portion 12b, respectively, and this portion constitutes an idling clearance setting means to be described later.

Furthermore, a presser foot lifting mechanism is shown in FIG. 4, which is a perspective view of the presser foot lifting lever stand 15 from a different angle.
On the presser foot lifting lever base 15, there is a presser foot lifting lever 16.
is pivotally supported, and one end is connected to the plunger of the electromagnetic solenoid S via a wire 17. The figure shows a state in which the solenoid S is energized, the plunger attracts the wire 17, and the intermediate presser rod holder 9 contacts the stopper 15a of the presser foot lifting lever base 15.

〔motion〕

Next, the operation in the above configuration will be explained. FIGS. 5 to 9 are link diagrams showing each operating state.

In the state shown in FIG. 2 in which the stopper 14 is in contact with the contact portion 12b of the deformable link 12, the intermediate presser shaft 5 swings as shown in the link diagram at that time in FIG. When the intermediate presser P moves,
They can reciprocate up and down as shown by solid lines and dotted lines, respectively. Note that a stopper 15a is provided to maintain _l0 .

Furthermore, as shown in FIGS. 3 and 6, if the stopper 14 does not contact the link contact portion 12b and there is a gap G greater than a predetermined amount, even if the intermediate presser shaft 5 swings, The presser foot P remains lowered and does not move.

When the clearance G is between the above two cases, when the intermediate presser shaft 5 swings as shown in FIG. 7, the intermediate presser P can reciprocate up and down as shown by solid lines and dotted lines, respectively.

Now, when the intermediate presser shaft 5 begins to swing and performs the movement shown by the dashed line, the intermediate presser rod holder 9 does not move and only when the gap G becomes zero does the intermediate presser rod holder begin to rise.

Therefore, by changing the amount of this gap G, the period during which the intermediate presser bar is held still can be changed.

That is, by adjusting the stopper 14 with a screw to appropriately set the gap G between the deformable link 12 and the contact portion 12b, the solid line P in the lift diagram in FIG.
As shown by the curve, the bottom dead center holding position of the intermediate presser P can be set, for example, during the _T2 period between _t1 and _t3 , so that even if the needle N rises, the fabric is securely placed on the throat plate. It does not float or flap when pressed, and can maintain a desired sewing quality.

In addition, in order to raise the intermediate presser P, as shown in FIG. 4, by releasing the energization of the solenoid S and releasing the wire 17 that has been pulled by the plunger, the presser foot lifting lever 16 is moved counterclockwise by the spring 16a. As it rotates and pushes up against the elastic force of the compression coil spring 11 that constantly presses the intermediate presser bar holder 9, the intermediate presser P rises as shown in FIG.

When the intermediate presser P rises, the intermediate presser P
As shown in the figure, even if the intermediate presser shaft 5 swings, it remains stationary.

In addition, in order to lower the intermediate presser P, solenoid S
By energizing the wire 17 and pulling the wire 17 with the plunger, the presser foot lifting lever 16 rotates clockwise against the elastic force of the spring 16a. descend.

〔Effect of the invention〕

As explained above based on the examples,
According to the present invention, a period in which the height of the bottom dead center of the vertical movement of the intermediate presser in an automatic sewing machine is maintained constant is maintained, and the work cloth is prevented from swinging vertically when forming a loop with the bobbin thread. It is possible to ensure the quality of the sewing product without any problems or poor thread tightness.

[Brief explanation of drawings]

FIG. 1 is a perspective view of essential parts of an embodiment of an intermediate presser device according to the present invention, FIGS. 2 to 4 are enlarged enlarged views of various parts of FIG. 1, and FIGS. 5 to 9 are Link diagram showing each operating state, 1st
FIG. 0 is a lift curve diagram of the needle and intermediate presser of this embodiment and the conventional example. A... Sewing machine main shaft (upper shaft), P... Intermediate presser, 1... Eccentric cam, 5... Intermediate presser shaft, 5a... Arm, 6... Link,
7... L-shaped link, 8... Link, 9... Intermediate presser bar holder, 10... Intermediate presser bar, {12... Deformed link, 12
b...Contact part, 14...Stopper} (idle movement clearance setting means), G...Gap.

Claims (1)

[Claims] 1. A motion conversion mechanism for converting the swinging motion of the intermediate presser shaft driven by an eccentric cam fixedly installed on the main shaft of the sewing machine into vertical reciprocating motion of the intermediate presser bar, at least part of the swinging motion. An intermediate presser foot device for a sewing machine, characterized in that it is equipped with idle movement clearance setting means for disabling the transmission of .