JPH074457B2 - Sewing machine cloth presser - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cloth pressing device for a sewing machine, and more specifically, it is stretched between an interlocking lever and a pressing lever when pressing a cloth by the operation of a driving means such as a solenoid. The present invention relates to an improvement of a cloth pressing device for a sewing machine, which presses the cloth pressing foot of the pressing lever against the cloth on the bed by the tension of the tension spring.

(Prior Art) In this type of presser foot device, in order to reliably press the cloth and prevent the cloth from slipping, a tension spring stretched between the interlocking lever and the presser lever has a large spring constant. It was common to be done. In the case where the cloth is pressed by the tension of the tension spring having a large spring constant, the tension of the tension spring greatly varies when the cloth thickness is different. Therefore, when pressing a thick cloth, the tension of the tension spring becomes excessively large, and this tension may exceed the capacity of the drive means (solenoid. In this case, the cloth cannot be pressed stably.

In order to solve such a problem, for example, Japanese Patent Laid-Open No.
There is a cloth pressing device disclosed in Japanese Patent Publication No. 56690. That is, in this case, by connecting the first tension spring having strong force and the second tension spring having weaker force in series, the tension spring having strong force is first pulled by the solenoid, and then A tension spring having a weak force is pulled by the restoring force of the spring to urge the presser foot.

(Problems to be Solved by the Invention) However, in the conventional one in which two tension springs having different forces are connected in series, the number of parts constituting the presser foot device increases and the structure becomes complicated. Occurs.

(Means for Solving Problems) Therefore, in the present invention, the feed lever movably arranged on the bed is provided with the interlocking lever whose one end is engaged with the pressing member operated by the driving means. In addition to being pivotally attached at the central portion, a presser lever having a presser foot at one end is pivotally attached to the feed base approximately at the center thereof, and between the other end of the interlocking lever and the other end of the presser lever. Is a cloth pressing device for a sewing machine, in which a tension spring is stretched, and the cloth pressing foot of the pressing lever is pressed against the cloth by the tension of the tension spring when pressing the cloth by the operation of the driving means.
The tension spring is composed of a high tension spring having a spring characteristic having a large tensile force and a small spring constant.

(Operation) Accordingly, the present invention reliably and stably presses the cloth by pressing the cloth presser foot of the presser lever against the cloth by the initial tension of the tension spring composed of the high tension spring and the restoring force due to the extension thereof. be able to. Furthermore, since the spring constant of the tension spring is set to be small, the tension of the tension spring does not largely change even when the cloth has various cloth thicknesses. Therefore, even in the case of thick cloth, the tension of the tension spring is prevented from exceeding the capacity of the driving means such as the solenoid and becomes excessively large, so that the thick cloth can be pressed stably.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1 which is a partially cutaway front view of the sewing machine pressing device, a feed table 2 is arranged on a bed 1a so as to be movable in parallel in the X and Y directions along a bed surface by a drive device (not shown). It is set up.

Above the feed table 2, at a predetermined position of the sewing machine arm 1b, a solenoid 3 which is a driving means for the work clamp is installed. The plunger 4 of the solenoid 3 is connected to a pressing member 6 for pressing the cloth via a toggle joint mechanism 5. The pressing member 6 is guided up and down by a guide pin 7 projecting downward at a predetermined position of the sewing machine arm 2,
When the cloth is pressed down, the plunger 4 of the solenoid 3 excited when the cloth is pressed down is lowered in a horizontal state.

A pair of interlocking levers 9 is supported on both sides of a support piece 8 projecting near the one side of the upper surface of the feed base 2 so as to be tiltable about a common lever shaft 10 at the substantially central portion thereof.
An engaging piece 11 which is always in contact with and engages with the lower surface of the pressing member 6 is attached to one end of the interlocking lever 9 so as to be rotatable around a pin 12.

Presser levers 13 are supported on both sides of the upper portion of the feed base 2 in a substantially central portion thereof so as to be tiltable about a horizontal lever shaft 16. One end of these presser levers 13 is the feed table 2
Is extended in a downwardly inclined shape toward one end surface of the. Further, one end portion of each presser lever 13 is fitted and inserted in an upper engaging hole of a cloth presser foot 17 which is arranged on one end surface of the feed base 2 so as to be able to move up and down. The presser foot 17 is moved up and down by tilting the presser lever 13 about the lever shaft 16. In addition, the presser foot 17 has a standing piece 17a
However, as shown in FIG. 2, after being fitted in a sliding groove 2a formed on one end face of the feed base 2 so as to be able to move up and down, by fastening a contact plate 18 to the end face of the feed base 2, It is attached to one end surface of the table 2. A pressing plate 30 for pressing the cloth on the bed 1a is attached to the lower end surface of the cloth pressing foot 17.

The other end of the pair of interlocking levers 9 and the pair of presser levers 13
Tensile springs 19 are respectively stretched between the other ends of the springs. When the cloth is pressed by exciting the solenoid 3, the tension of the tension spring 19 presses the cloth pressing foot 17 of the pressing lever 13 against the cloth on the bed 1.

The tension spring 19 is composed of a well-known high tension spring (usually referred to as a high tension spring) having an extremely large initial tension, unlike the tension spring for general structure defined in JIS B2704. That is, the tension spring 19 is formed by closely coiling a spring wire in a state in which a torsion stress exceeding its elastic limit (yield point) is applied to the spring wire (for details, see Japanese Patent Publication No. 43-12994). I want to be). Then, the initial tension is set large enough to press the cloth without shifting the cloth, and the spring constant is set as small as possible.

Further, in this embodiment, the pair of presser levers 13 are divided by the first and second levers 14 and 15 having the horizontal lever shaft 16 as the center of rotation. In FIG. 1, the first lever 14 on the right side is
The first lever is inserted so as to be rotatable around the lever shaft 16.
Hook 19a formed at the lower end of tension spring 19 at the tip of 14
Is locked. The second lever 15 on the left side is fitted at its base end portion so as to be rotatable about the axis of the lever shaft 16,
The tip portion is fitted and inserted into an engagement hole penetrating the upright piece 17a of the presser foot 17. An arcuate adjustment hole 20 centering on the lever shaft 16 is formed on the base side of the first lever 14, and a female screw is formed on the base side of the second lever 16 at a position facing the adjustment hole 20. ing. Then, the tightening bolt 21 is passed through the adjustment hole 20 of the first lever 13 and the second lever 15
By tightening to the female screw, both the first and second levers 14,1
5 is integrally connected, and by loosening the tightening bolt 21, the first and second levers 14 and 15 can be adjusted in angle within the range of the adjustment hole 20 about the lever shaft 16. As described above, the presser lever 13 constituted by the first and second levers 14 and 15 is first
It is biased clockwise in the figure. This return spring 22
One end thereof is hooked on the upper surface of the feed base, the central portion is wound around the axis of the lever shaft 16, and the other end side is hooked on the second lever 15.

As shown in FIG. 3, adjustment pieces 14a, 15a facing each other with a predetermined gap are vertically formed at predetermined positions of the base end portion of the first lever 14 and the second lever 15, respectively. Of these two adjusting pieces 14a, 15a, one adjusting piece 15a is screwed with an adjusting screw 23 capable of moving forward and backward with respect to the other adjusting piece 14a. By moving the adjusting screw 23 forward and backward, the angles of the first and second levers 14 and 15 can be adjusted around the lever shaft 16.

In this embodiment configured as described above, when the solenoid 3 is excited, its plunger 4 is attracted and the pressing member 6 is lowered via the toggle joint mechanism 5. Then, the interlocking lever 9 is rotated counterclockwise in FIG. 1 about the lever shaft 10. Then, via the tension spring 19, the presser lever 13 resists the urging force of the return spring 19 and is rotated counterclockwise about the lever shaft 16, and the cloth presser foot 17 is lowered toward the surface of the bed 1a. . At this time, since the initial tension of the tension spring 19 is larger than the spring force of the return spring 22, the tension spring 19 functions as a link without extending.

As described above, with the solenoid 3 activated,
The lower surface of the presser plate 30 attached to the lower end of the work clamp foot 17 is the bed 1a.
The first and second levers 14 and 15 of the presser lever 13 are angle-adjusted about the lever shaft 16 so that they come into contact (0 contact) with no gap on the upper surface of the. This angle adjustment is performed by tightening the tightening bolt 21 that fastens the first and second levers 14 and 15 integrally.
The adjustment screw 23 is screwed in and unscrewed in the state of being loosened.

In addition, a feed plate along the upper surface of the bed 1a is provided at the base end of the feed base 2.
When the cloth is clamped between the feed base 24 and the holding plate 30, the lower surface of the holding plate 30 is the feed plate.
The angle of the first and second levers 14 and 15 of the presser lever 13 is adjusted about the lever shaft 16 so that they come into contact with the upper surface of 24 without a gap (zero hit).

After the angles of the first and second levers 14 and 15 are adjusted in this way, the cloth is set on the upper surface of the bed 1a (or the feed plate 24) and the solenoid 3 is actuated. The presser foot 17 is lowered toward the cloth through the tension spring 19 and the presser lever 13. Then, the lower surface of the presser plate 30 of the presser foot 17 contacts the cloth, and the descending of the presser foot 17 is stopped.

After the lowering of the presser foot 17 is stopped, the pressing member 6 is subsequently lowered to the bottom dead center by the solenoid 3. After the lower surface of the presser plate 30 of the presser foot 17 comes into contact with the cloth, the interlocking lever 9 pulls the tension spring 19 by an amount corresponding to the thickness of the cloth while the pressing member 6 descends to the bottom dead center. It is rotated counterclockwise while stretching. And the tension spring
The presser lever 13 is urged counterclockwise by the tension of 19,
By pressing the pressing plate 30 of the presser foot 17 against the cloth, the cloth is pressed.

That is, the tension of the tension spring 19 is F, the spring constant is c,
If the elongation (corresponding to the thickness of the fabric) is t, then F = initial tension + tc.

The tension spring 19 is a high tension spring (high tension spring).
The initial tension is set large enough to press the cloth without slipping the cloth, and the spring constant c is set as small as possible. For this reason,
Even when the cloths having different cloth thicknesses are selectively pressed, the tension F of the tension spring 19 is prevented from being largely changed.
From this, even when pressing a thick cloth, the tension F of the tension spring 19 is positively prevented from becoming larger than the suction force of the solenoid 3, so that even a thick cloth can be reliably and stably held. It becomes possible to hold down well.

The present invention is not limited to the above embodiment.
For example, in the above embodiment, the presser lever 13 is
Although the angle is adjustable by the second levers 14 and 15, the present invention is not limited to this, and the presser lever 13 may be a single lever.

(Effects of the Invention) As described above, according to the present invention, the presser foot of the presser lever is pressed against the cloth by the tension of the initial tension of the tension spring composed of the high tension spring and the restoring force due to the extension thereof. The fabric can be pressed reliably and stably. Further, since the tension spring is set to have a large initial tension and a small spring constant, the tension of the tension spring does not fluctuate greatly even when the cloth has various cloth thicknesses. Therefore, even in the case of thick cloth, the tension of the tension spring is prevented from exceeding the capacity of the driving means such as the solenoid and becomes excessively large, and the thick cloth can be pressed stably.

Moreover, since a tension spring made of a high tension spring is stretched between the interlocking lever and the pressing lever, there is an effect that the number of parts is small and the structure can be easily made to reduce the cost.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a front view showing a partially broken sewing machine presser device, FIG. 2 is a plan view taken along line II-II of FIG. 1, and FIG. FIG. 6 is a cross-sectional view showing an angle adjusting mechanism of first and second levers which constitute a presser lever. 1a ... Bed 2 ... Feeding table 3 ... Solenoid (driving means) 6 ... Pressing member 9 ... Interlocking lever 13 ... Pressing lever 17 ... Cloth pressing foot 19 ... Tension spring (high tension spring)

Claims (1)

[Claims] 1. An interlocking lever, one end of which is engaged with a pressing member actuated by a drive means, is pivotally attached to the feed table movably disposed on the bed at a substantially central portion thereof, and the feed is provided. A presser lever having a presser foot at one end is pivotally attached to the base at a substantially central portion thereof, and a tension spring is stretched between the other end of the interlocking lever and the other end of the presser lever to drive the drive mechanism. A cloth pressing device for a sewing machine, which presses the cloth pressing foot of a pressing lever against a cloth by the tension of the tension spring when the cloth is pressed by the operation of the means, wherein the tension spring has a large tensile force and a spring constant. A cloth pressing device for a sewing machine, characterized in that it is constituted by a high tension spring having a small spring characteristic.