JPS5911730Y2 - Sewing machine presser foot device - Google Patents

Description

[Detailed explanation of the idea] Technical field This invention relates to a presser foot device for a sewing machine.

PRIOR ART Conventionally, in a sewing machine configured to transport a workpiece cloth on a workpiece cloth support surface by cooperation of a feed dog and a presser foot, a cloth is used to apply presser pressure to the presser foot. A presser spring and an adjusting means for adjusting the presser foot pressure of the presser spring are provided, and the presser foot pressure is adjusted and set to a predetermined value according to the material, thickness, etc. of the fabric to be processed prior to sewing. Sewing was carried out in this condition.

However, in recent years, there has been a remarkable trend toward higher speeds in industrial sewing machines, etc., and the rotational speed of the main shaft of the sewing machine has increased to 1000 O r
．． l). m. There are also high-speed sewing machines on the market that can reach this level.

In such high-speed sewing machines, various adverse effects occur when sewing is performed using the initially set constant presser foot pressure as described above.

In other words, if the presser foot pressure is set strongly to match the high-speed operation of the sewing machine, when the sewing machine is operated at low speed at the start of sewing or during sewing, the presser foot pressure set to be strong will not be applied to the workpiece cloth. On the other hand, if the presser foot pressure is set too low to match the low speed operation of the sewing machine,
When the sewing machine was operated at high speed during sewing, the presser foot was pushed up and lifted up due to the high speed operation of the feed dog, causing a phenomenon in which the cloth was not fed properly.

This invention was made to solve the above-mentioned defects in conventional sewing machines, and its purpose was to change the pressure of the presser foot in response to the rotational speed of the main shaft of the sewing machine. An object of the present invention is to provide a novel presser foot device for a sewing machine that can apply appropriate presser foot pressure to a workpiece cloth from the start of sewing to high-speed operation even in a high-speed sewing machine.

EXAMPLE Below, an example embodying this invention will be described with reference to the drawings.A presser foot 1 is supported on an arm portion (not shown) of a sewing machine frame so as to be movable up and down, and a feed dog (
A presser foot 2 is removably attached so as to face a presser foot (not shown), and a presser bar holder 3 is fixed approximately at the center.

By rotating the presser foot lifting lever 4 attached to the arm, the presser bar 1 is lifted from the lowered position shown in FIGS. 1 and 2 via the presser bar holder 3. ing.

An electromagnetic solenoid 8 including an armature 5 and a solenoid body 7 having an excitation coil 6 is provided in the arm above the presser bar holder 3 .

That is, an insulator 9 is provided at the center of the solenoid body 7 and includes a cylindrical part 9a extending in the vertical direction and a pair of upper and lower flange parts 9b, and the armature 5 is mounted in the upper part of the cylindrical part 9a in the vertical direction. The excitation coil 6 is inserted and fitted so as to be relatively movable, and is wound around the outer periphery of the cylindrical portion 9a for applying an attractive force to the armature 5.

A cylindrical stopper 10 for regulating the relative movement of the armature 5 is disposed at the lower part of the cylindrical portion 9a of the insulator 9, and the upper end of the presser rod 1 is inserted into the stopper 10 to stop the armature. It is screwed onto the lower end of 5.

When the excitation coil 6 is energized, the armature 5 is attracted downward, and based on the suction force, downward pressure is applied to the presser foot 1 and the presser foot 2, and presser foot pressure is applied to the work cloth. It is now granted.

. An adjustment screw 11 having an insertion hole 11a is screwed into the arm portion of the sewing machine above the armature 5, and its head protrudes from the upper surface of the arm portion of the sewing machine.

A pressing rod 12 is provided between the adjusting screw 11 and the armature 5.
is provided, and an insertion hole 11 for the adjustment screw 11 is provided at its upper end.
a, and is connected to the armature 5 at its lower end.

A cloth presser spring 13 is wound around this presser rod 12, and when the presser foot 1 is lowered, the spring force is applied to the cloth presser foot 2.
The pressure of the presser foot is applied to the workpiece cloth through the workpiece cloth, and the presser foot pressure can be adjusted by changing the screwing amount of the adjustment screw 11 according to the material, thickness, etc. of the workpiece cloth. .

Next, the operating means for moving the solenoid body 7 of the electromagnetic solenoid 8 up and down to change the attraction force of the armature 5 will be explained.

A cam body 14 is rotatably supported within the arm portion below the solenoid body 7, and is rotated in forward and reverse directions by a servo motor 15 connected to the cam shaft 14a.

A tension spring 1 is provided between the solenoid body 7 and the arm portion.
6 is provided, and its spring force holds the solenoid body 7 in an engaged state with the cam body 14.

When the cam body 14 is rotated by starting the servo motor 15 during operation of the sewing machine, the solenoid body 7 is moved up and down following the change in the cam surface of the cam body 14, and the armature 5 and solenoid body 7 By changing the relative positional relationship with ', the attractive force of the armature 5 when the excitation coil 6 is energized is changed.

Next, a speed detection means for generating an output signal for controlling the operation of the actuation means in response to the rotational speed of the main shaft 17 of the sewing machine will be explained.

A permanent magnet 19 is fixed to the outer peripheral surface of a pulley 18 fixed to the right end of the main shaft 17 of the sewing machine, and is configured to rotate integrally with the main shaft 17.

A Hall element 20 as a speed detector is provided on the sewing machine so as to face the permanent magnet 19, and detects the rotational speed of the main shaft 17 in cooperation with the permanent magnet 19.

Then, the detection signal is input to a controller 21 provided within the machine frame, and a signal for driving and controlling the servo motor 15 is output from the controller 21 based on the input signal.

That is, the rotation speed of the main shaft 17 is a predetermined speed (approximately 1
500 to 200 O r , p, m,) or less, the drive of the servo motor 15 is stopped by the output signal from the controller 21, and the lower cam surface of the cam body 14 is engaged with the solenoid body 7. By stopping the rotation of the cam body 14, the armature 5 and the stopper 1 are
When the distance from The distance between the armature 5 and the stopper 10 is changed and adjusted by moving the solenoid body 7 up and down in accordance with changes in the cam surface of the body 14.

Then, the suction force acting on the armature 5 of the electromagnetic solenoid 8 is changed according to the interval, and accordingly, the presser foot pressure is changed.

Next, the operation of the presser foot device configured as described above will be explained.

Now, with the sewing machine stopped, raise the presser foot 2 to set the work cloth on the workpiece cloth support surface, and then lower the presser foot 2 to adjust the settings in advance using the adjustment screw 11. The presser pressure of the presser spring 13 is applied to the workpiece cloth via the presser foot 2, and the workpiece cloth is reliably held between the presser foot 2 and the workpiece cloth support surface.

At this time, armature 5 and stopper 1 of electromagnetic solenoid 8
The solenoid main body 7 is held in a state where the distance from the solenoid 7 is set to be wide.

When the sewing machine is operated with this work cloth set,
The excitation coil 6 of the electromagnetic solenoid 8 is energized, and the feed dog is operated as the main shaft 17 rotates, and the feed dog and the presser foot 2 work together to impart feed to the work cloth.

However, since the rotational speed of the main shaft 17 is low immediately after the sewing machine starts sewing, the servo motor 15 and the cam body 14 are not operated by the action of the controller 21, and therefore the distance between the armature 5 and the stopper 10 is small. The armature 5 is not narrowed by the upward movement of the solenoid body 7, and a state in which a large suction force is not applied to the armature 5 is maintained. Pressure is applied.

The workpiece cloth is transported accurately without any movement due to the cooperation between the presser foot 2 and the feed dog.

Further, the presser foot pressure of the presser spring 13 immediately after the start of sewing can be adjusted by turning the adjusting screw 11, for example, increasing the presser foot pressure for thick work fabrics and increasing the presser foot pressure for thin work fabrics. This can be changed as appropriate, such as by reducing the pressure of the presser foot, depending on the thickness and material of the fabric to be processed.

When sewing is started as described above and the rotation speed of the main shaft 17 of the sewing machine is increased beyond a predetermined speed, the controller 21 operates the servo motor 15 and the cam body 14 according to the amount of increase, and the cam body 14 is rotated. By moving the solenoid body 7 upward following the change in the cam surface, the distance between the armature 5 and the stopper 10 is narrowed.

As a result, the suction force of the armature 5 is increased, and downward pressure is applied to the increasing rod 1 and the presser foot 2, and the work cloth is subjected to the presser pressure by the presser spring 13 and the presser foot by the electromagnetic solenoid 8. Pressure is applied in a superimposed manner.

Therefore, while the sewing machine is operating, the pressure of the presser foot 2 is increased as the rotational speed of the main shaft 17 of the sewing machine increases, and there is no fear that the presser foot 2 will be pushed up and float due to the high-speed operation of the feed dog. Good cloth feeding is always performed.

Effects As detailed above, this invention is designed to change the pressure of the presser foot in response to the rotational speed of the main shaft of the sewing machine, so even high-speed sewing machines can operate at high speed from the start of sewing. This provides an excellent effect in that an appropriate presser foot pressure can be applied to the work cloth up to .

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of this invention, and FIG. 2 is an enlarged sectional view showing the main parts of this invention. Presser bar...1, Presser foot...2, Armature...5, Excitation coil...6, Solenoid body...7, Electromagnetic solenoid...
...8, Cam body...14, Servo motor...
...15 (the operating means is constituted by the above-mentioned 14.15 etc.), main shaft ...17, permanent magnet ...
...19, Hall element...20, controller...21 (a speed detection means is constituted by the above-mentioned 19.20, etc.).

Claims (1)

[Scope of Claim for Utility Model Registration] 1. A presser foot 1 which is supported so as to be vertically movable according to the features of the sewing machine and has a presser foot 2 attached to its lower end, an armature 5 connected to the presser foot 1, and an armature 5 connected to the presser foot 1; The armature 5 has an excitation coil 6 for applying an attractive force to the armature 5.
an electromagnetic solenoid 8 including a solenoid main body 7 that is relatively movable along the main shaft 17; 20, etc., and moves the solenoid body 7 so as to increase the suction force of the armature 5 and the presser foot pressure as the rotational speed of the main shaft 17 increases. A presser foot device for a sewing machine, characterized in that it is provided with actuating means 14, 15, etc. 2. In order to move the solenoid main body 7, the actuating means is connected to a cam body 14 rotatably supported on the machine frame, and the cam body 14 is connected to The presser foot device for a sewing machine according to claim 1, further comprising a servo motor 15 for rotating the cam body 14 in response to an output.