JPS608855Y2 - Sewing machine presser foot lifting device - Google Patents

Description

[Detailed description of the invention] This invention relates to a presser foot lifting device for a sewing machine, and is particularly suitable for sewing the front and back sides of flexible bedding. The sewing needle exerts an appropriate pressing action on the sewing material, and when the sewing needle rises and leaves the surface of the sewing material, and when the sewing material is transferred, a gap is created between the sewing needle and the surface to eliminate the pressing action. It is something.

Some prior art regarding presser foot devices for this kind of purpose (
For example, Tokuko Sho 47-15383, Jitsugoku Sho 52-708
), etc., but the present invention compensates for the shortcomings of these prior art techniques and aims to improve the performance of sewing operations smoothly and satisfactorily.

Hereinafter, embodiments of the device of the present invention will be described based on the drawings.

Reference numeral 1 denotes a frame of the head of the sewing machine, 2 an upper shaft, and 3 a drive cam which is fixed to the upper shaft with a screw 4 and follows the rotation of the upper shaft 2.

Reference numeral 5 denotes a connecting rod whose base is loosely fitted into the drive cam 3, and at its end is a driven arm 6 having a long hole 6a, the setting position of which can be adjusted with a pin screw 7, washer 8, and nut 9 via a bushing. attached.

Reference numeral 10 denotes a drive shaft, which is loosely fitted and supported by bushes 11 and 12 fixed to the arm 1, and one end of which is tightly fitted into the driven arm 6.

The drive shaft 10 has an arm lea, and a pin 13 having a threaded shaft is fixed to the end of the arm by a nut 14.

15 is a presser bar, which is attached to the upper and lower buttons 1 fixed to the machine frame 1.
6.17, and a presser foot 1 is fitted in the lower part of the presser foot 1.
8 is removably attached with screws 19.

20 is a presser bar holder whose base is fixed to the presser bar 15 with a screw 21, and its end 20a is loosely fitted into a groove la of the machine frame so that it can only slide vertically.

22 is a presser rod driving member that loosely fits on the presser rod 15 and has an extension portion 22b that loosely fits into the U-shaped cross-sectional groove 22a and the machine frame groove 1a.

The pin 13 integrated with the drive shaft 10 is engaged with the U-shaped cross-sectional groove 22a of the presser rod drive member.

Reference numeral 23 denotes an L-shaped spring receiver, the upper part of which is loosely fitted onto the presser bar 15, and a coil spring 24 between this part and the presser bar holder 20.
is arranged, and the lower part is fixed to the extension part 22b of the presser rod drive member by screws 25.25.

Note that 26 is a cushion rubber loosely fitted between the presser bar holder 20 on the presser bar and the presser bar drive member 22.

In addition, in the state shown in the first figure (the presser bar is at the highest position), a slight gap is maintained between the bent upper surface of the spring receiver 23 and the lower end surface of the bushing 16, and a gap is maintained between the bent lower surface and the presser bar holder 20. The coil spring 24 disposed therebetween has no play and is close to its free length.

The present registration device is constructed as described above, and its operating status will be described next.

That is, as the upper shaft 2 rotates, the presser bar 15 performs vertical reciprocating motion.

For reference, the drivetrain path is shown below using the illustrated part numbers.

Therefore, when the presser foot 18 is separated from the cloth, the spring load of the coil spring 24 does not act on members such as the pin 13.

As shown in FIG. 2, when the arm portion 10a of the drive shaft 10 moves downward and the presser foot 18 comes into contact with the sewing material, the downward movement of the presser bar 15 is restricted, but the presser foot sticks to the presser bar drive member 22. The coil spring 24 is compressed by the spring receiver 23, and a desired spring load is applied.

Before describing the excellent effects of the device of the present invention, an outline of the prior art will be provided here.

In the one shown in FIG. 4, a coil spring 23A is interposed between a washer 21A provided on a presser bar 3A and a machine frame IA, and a hanging piece 19A is pivotally supported at the tip of a side arm 18A.
A pin 22A protruding from the washer 21A is slidably fitted into the elongated hole 20A.

Therefore, the hanging piece 19A is constantly subjected to a load resisting the spring pressure of the coil spring 23A in addition to the mass of the moving members including the presser bar 3A.

This increases the load acting on the drive cam (not shown) that follows the rotation of the upper shaft, resulting in disadvantageous conditions such as durability.

Moreover, even when the presser foot pressure W shown in FIG. 4-1 is unnecessary, a large spring pressure T acts, increasing the load on each mechanism.

In the one shown in FIG. 5, a spindle 12B is fitted into a protrusion 10B of a presser bar holder (not shown) fixed to a presser bar 2B, and coil springs 15 and 16B are interposed above and below the protrusion 10B, respectively.

These members are arranged in a vertically elongated hole 14B of a vertical rod 13B which is connected to the horizontal arm 6B so that its mounting position can be adjusted.

This device holds the protrusion 10B by the balance between the coil springs 15B and 16B and transmits vertical motion to the presser bar 2B.

Therefore, when the sewing machine rotates at variable speeds, the presser bar 2B vibrates abnormally due to its inertia, resisting the spring action of the coil springs 15B and 16B, and becomes larger than the vertical movement of the vertical rod 13B.

Furthermore, if the rotation of the upper and lower coil springs and the sewing machine reach a resonance point, this phenomenon will become much larger, and there is a risk that the device will not be able to perform its functions.

See Figure 5-1. In the device of the present invention, the desired presser foot pressure is applied only at the necessary stroke points during sewing, as shown in Figure 1-1, and an effect that cannot be seen in the above two rows is achieved. There are many benefits to sewing work.

[Brief explanation of the drawing]

FIG. 1 is a front view of the jaw of a sewing machine equipped with the device of the present invention and shows when the presser bar is raised, and FIG. 2 is similar to FIG. 1 and shows when the presser bar is lowered. Fig. 3 is a cross-sectional view of the main parts of the proposed device, Fig. 4 is an explanatory view of the configuration of a presser foot lifting device of a conventional sewing machine, Fig. 4-1 is an explanatory view of the spring action in the configuration of Fig. 4, and Fig. 5 The figure is an explanatory diagram of the configuration of a presser foot lifting device of another conventional sewing machine.
Figure 1-1 is a diagram illustrating the spring action in the configuration of the present invention. 1...Machine frame, 2...Upper shaft, 3...
...Drive cam, 5...Connection rod, 6...
... Driven arm, 10 ... Drive shaft, 13 ...
Zen, 15... Presser bar, 18... Presser foot, 20... Presser bar holder, 22... Presser bar drive member, 23...・Spring holder, 24...
...Coil spring.

Claims (1)

[Scope of utility model registration request] A drive shaft having an arm whose rotation angle can be adjusted by a drive cam that follows the rotation of the upper shaft, a presser bar having a presser at its lower end that reciprocates up and down via the drive shaft, and a presser bar holder fixed to the presser bar. At the same time, a presser rod driving member that receives a pin that moves up and down integrally with the arm portion of the drive shaft is loosely fitted, the negative side is fixed to the presser rod driving member, and the other side is loosely fitted to the presser rod. A presser foot lifting device for a sewing machine, in which a coil spring is stretched between a spring receiver and the presser bar holder.