JP2903624B2 - Sewing machine presser foot device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cloth presser for a sewing machine that presses a work cloth with a predetermined pressure and fixes the work cloth on a bed.

2. Description of the Related Art In a cloth presser of a sewing machine, a presser bar having a presser foot is pressed downward by a presser spring, thereby fixing a work cloth at a needle drop position on a bed via a presser foot. It has been like that. If the biasing force of the presser spring is too small, the work cloth cannot be fixed satisfactorily. On the other hand, if the biasing force of the presser spring is too large, the cloth cannot be fed properly. That is, by providing an adjusting screw for adjusting the length of the presser spring, the user can turn the adjusting screw to arbitrarily set the urging force of the presser spring and, consequently, the pressure of the work cloth by the presser foot. It has been like that.

[Problems to be Solved by the Invention] In the sewing machine, it is necessary to change the presser foot used for the cloth presser according to the type of sewing operation such as straight stitching and zigzag stitching. Also, since each presser foot is different in size depending on its type, changing the presser foot changes the height position of the presser bar, and accordingly, the length of the presser spring changes and the presser foot presses the work cloth. The pressure changes. For this reason, conventionally, every time the presser foot used for the sewing operation is changed, the user has to rotate the adjusting screw to adjust the presser pressure of the work cloth, and there is a problem that operability is poor. . In particular, when sewing machines are used in sewing factories, etc., the presser foot is frequently changed due to high-mix low-volume production. Therefore, there is a problem that defective products are easily generated.

Accordingly, an object of the present invention is to provide a cloth presser device for a sewing machine that can automatically perform presser pressure adjustment in accordance with a change of a presser foot.

[Means for Solving the Problems] That is, the present invention made in order to achieve the above-mentioned object,
A presser bar attached to the arm of the sewing machine so as to be able to move up and down, and a presser foot attached to the lower end, and biasing the presser bar downward,
A presser spring that applies a predetermined pressure to the presser foot, and a presser adjusting member that adjusts the pressure applied to the presser foot when the presser foot is at the cloth presser position by adjusting the biasing force of the presser spring. Detecting means for detecting a height position of the presser bar when the presser bar is at the lowered position and the presser foot is at the cloth presser position; and Adjusting member drive control means for driving the presser adjusting member based on the height position of the presser bar, and controlling the pressure applied to the presser foot to a predetermined pressure when the presser foot is at the cloth presser position, It is characterized by having.

[Operation] In the presser foot device of the sewing machine of the present invention configured as described above, first, when the presser foot mounted on the presser bar is at the presser foot position, the detecting means detects the height position of the presser bar. The adjusting member drive control means drives the presser adjusting member based on the detection result to control the pressure applied to the presser foot when the presser foot is at the cloth presser position, that is, the presser pressure of the work cloth.

That is, the height position of the presser bar when the presser foot is at the presser foot position corresponds to the length of the presser spring at the presser foot position, and in turn, the presser pressure of the work cloth by the presser foot. Therefore, in the present invention, the pressing pressure of the work cloth is controlled to a predetermined pressure by controlling the driving of the presser adjusting member in accordance with the height position of the presser bar.

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

As shown in FIG. 2, a presser bar 4 to which a cloth presser 3 is attached and a needle bar 6 to which a sewing machine needle 5 is mounted are provided on the arm 2 of the sewing machine 1 so as to be able to move up and down, respectively. .
The presser bar 4 is supported in the arm 2 via a presser bar storage case 7 fixed to the inside of the arm 2 as shown in FIG. 3 so that the presser bar 4 can be moved downward by a presser spring 35 described later. When in the position, the presser foot 8 provided on the cloth presser 3 is urged downward so that the work cloth disposed on the bed 9 of the sewing machine 1 can be pressed at a predetermined pressure.

As shown in FIG. 3, the cloth presser 3 is formed in a circular umbrella shape, and is formed by rotating a presser foot support 12 having a plurality of protrusions 11 for mounting a presser foot on an outer wall, and a presser foot support 12. A mounting member 13 for movably supporting the work clamp 3 and detachably fixing the work clamp 3 to the presser bar 4 is constituted as a main part.

The attachment member 13 is formed in an umbrella shape similarly to the presser foot support 12, and a hole 14 for fixing the presser foot support 12 is formed at the center thereof. A hole 15 having a diameter larger than that of the hole 14 is formed in the center of the presser foot support 12, and the presser foot support 12 and the mounting member 13 are overlapped with each other.
By inserting a step screw 16 through 15 and tightening the step screw 16 with a nut 17, the presser foot support 12 can be attached to the mounting member 13.

On the other hand, a plurality of protrusions 11 for attaching the presser foot are respectively located on the extension line of the axis of the presser bar 4 by the rotation of the presser foot support 12 on the mounting member 13, and the presser foot 8 attached to the protrusion 11 is A ball 19 is provided that fits into a recess 18 formed in the presser foot support 12 when it is disposed at the presser position. The ball 19 is urged toward the presser foot support 12 by two leaf springs 20 and 21 fixed between the nut 17 and the mounting member 13, and the urging force causes the ball 19 to move. It bites into the recess 18 and the presser foot support 12 is firmly fixed. As shown in FIG. 4, three protrusions 11 are formed on the presser foot support 12, and different presser feet 8 are mounted on each of the protrusions 11 via mounting screws 11a, whereby the presser foot support 12 is formed. Is rotated so that the presser foot 15 used for the sewing operation can be selected from three types of presser feet.

Of the two leaf springs 20 and 21, the outer leaf spring 20 is formed larger than the inner leaf spring 21 so as to protrude upward from the position where the ball 19 is pressed. On the other hand, on the arm 2 side,
When the presser bar 4 is at the raised position, an engaging projection 22 that engages with the leaf spring 20 protruding above and displaces the leaf spring 20 in the direction of arrow A shown in FIG. 4 is fixed. Therefore, when the presser bar 4 is at the raised position, that is, when the presser foot 8 is disengaged from the cloth presser position and sewing is not performed, the urging force for urging the ball 19 toward the presser foot support 12 decreases. ,
The force of biting into the concave portion 18 of the ball 19 is reduced, and the presser foot support 12 can be rotated with a small force.

Further, teeth 12a are formed on the periphery of the presser foot support 12 so that the presser foot support 12 itself becomes a gear that rotates around the stepped screw 16. When the presser bar 4 is at the raised position, The teeth 12a mesh with a gear 23 fixed to the arm 2 side, and the presser foot support 12 can be rotated by rotation of the gear 23.

The gear 23 includes an air cylinder 25 that reciprocates a rod 24 by air pressure input from outside, and a rod 24
Receiving a rotational force transmitted from a driving device 27 constituted by a cam plate 26 rotated at a predetermined angle by reciprocation of
The presser foot support 12 is rotationally driven.

Next, an adjusting screw 30 as a presser adjusting member for adjusting the pressurizing pressure of the work cloth by the presser foot 8 disposed at the cloth presser position is screwed into the upper portion of the arm 2, and the adjusting screw 30 is rotated. By adjusting the insertion amount of the adjusting screw 30 into the arm, the pressing pressure of the work cloth can be adjusted. The arm 2 has a drive motor 32 for rotating the adjustment screw 30 via a timing belt 31 and an adjustment screw
A potentiometer 33 for detecting the amount of the adjusting screw 30 inserted into the arm from the height position of the tip portion 30 on the arm 2 is provided, and the adjusting screw 30 is inserted into the arm based on a signal from the potentiometer 33. While checking the amount of insertion, the amount of insertion of the adjustment screw 30 into the arm via the drive motor 32,
That is, the pressing pressure of the work cloth by the presser foot 8 can be automatically adjusted.

Hereinafter, a control system for controlling the pressure of the work cloth will be described with reference to FIG. In FIG. 1, the configuration of the control system for the presser foot support 12, the mounting member 13 and the like for selecting the presser foot 8 from the three types of presser feet and disposing it at the cloth presser position will be described. Omitted for simplicity.

As shown in FIG.
A presser spring 35, whose movement in the lateral direction is restricted by a presser spring guide 34, is fitted between the presser bar 4 and the presser bar 4. The presser bar 4 is provided with a well-known presser bar holder 36,
By displacing the lower end of the presser bar holder 36 up and down via the lever 37, the presser bar 4 is moved up and down.

The lever 37 is formed in a U shape, and is rotatably fixed in the arm 2 around the curved portion 37a. The lever 37 is connected via a link 39 to one end of a rotating plate 38 fixed in the arm 2 similarly to the lever 37. The rod 41 of the actuator 40 is
By driving the actuator 40 to displace the rod 41 in the vertical direction in the drawing, the rotating plate 38 and the link
The lever 37 is rotated via 39 to raise and lower the presser bar 4.

Next, a magnet above the presser bar holder 36 of the presser bar 4
The holding element 42 is fixed, and the magnetic force from the magnet 42 is detected by a Hall element 43 as detection means fixed and positioned in the arm 2 so that the height position of the presser bar 4 can be detected. The control signal as the adjustment member drive control means together with the detection signal from the potentiometer 33 for detecting the insertion amount of the adjustment screw 30 into the arm 2
Entered in 50.

The control circuit 50 includes a CPU 50a, a ROM 50b, a RAM 50c, and an input / output port 5.
0d and a well-known microcomputer centered on a bus line 50e connecting these components, and together with detection signals from the potentiometer 33 and the hall element 43, an up / down switch 5 for issuing an up / down command for the presser bar 4.
1, a presser pressure for reading a command signal from an operation panel 53 including a presser pressure setting switch 52 for setting a target presser pressure of the work cloth, and driving the drive motor 32 to control the presser pressure of the work cloth. Control, presser bar lifting control for driving the actuator 45 to raise and lower the presser bar 4, and the like are executed.

Next, the presser pressure adjusting process, which is a main process according to the present invention, which is executed by the control circuit 50, will be described with reference to the flowchart shown in FIG. This process is repeatedly executed at predetermined time intervals together with the presser bar lifting control when the sewing machine stops driving, that is, when sewing stops.

As shown in the figure, when the process is started, first, S11 is executed, and the presser bar 8 is lowered by a presser bar lifting control process (not shown) in accordance with a lifting command from a lift switch, and the presser foot 8 is now at the cloth presser position. It is determined whether or not. And this S1
If it is determined in step 1 that the presser foot 8 is not at the presser foot position, the process is terminated once. If it is determined that the presser foot 8 is at the presser foot position, the process proceeds to S13, where The height position of the presser bar 4 is detected based on the detection signal, and the flow shifts to S15.

In S15, by reading the operating state of the presser pressure setting switch 52, the currently set target presser pressure is detected, and the presser pressure is determined based on the target presser pressure and the detected height position of the presser bar 4. A target insertion amount of the adjustment screw 30 into the arm 2 for adjusting to the target holding pressure is calculated. That is,
The pressing pressure of the work cloth by the presser foot 8 is determined by the urging force of the presser bar 4 by the presser spring 35, and the urging force depends on the height position of the presser bar 4 and the amount of the adjustment screw 30 inserted into the arm 2. Is determined by the length of the presser spring 35 determined by
In step S15, the target of the adjusting screw 30 for adjusting the presser pressure to the target presser pressure from the target presser pressure set by the presser pressure setting switch 52 and the height position of the presser bar 4 detected by the Hall element 43. The insertion amount is calculated.

When the target insertion amount of the adjusting screw 30 is calculated in S15, the following S
Then, based on the detection signal from the potentiometer 33, the actual insertion amount of the adjusting screw 30 in the arm 2 is detected.
The drive motor 32 is driven such that the actual insertion amount becomes the target insertion amount obtained in S15. And in the following step S19,
It is determined whether or not the actual insertion amount of the adjusting screw 30 into the arm has reached the target insertion amount obtained in S15, and if the actual insertion amount has reached the target insertion amount, the process is temporarily terminated, and so on. If not, the process returns to S17.

As described above, in this embodiment, when the sewing operation of the sewing machine is stopped, the presser bar 4 is lowered, and when the presser foot 8 is disposed at the cloth presser position, the height position of the presser bar 4 and the target presser pressure are set. Then, the drive motor 32 is driven based on this, and the amount of insertion of the presser screw 30 into the arm 2 is automatically adjusted. Therefore, according to this embodiment, if the presser pressure is set by operating the presser pressure setting switch 52, the presser foot support 12 is driven to rotate by the driving device 27, and the presser foot 8 used for the sewing work is rotated.
Is changed, even if the height position of the presser bar 4 changes,
The presser foot pressure can be automatically adjusted accordingly, and the operability of the sewing machine can be improved. Further, in this embodiment, the target presser pressure can be set from the outside by the presser pressure setting switch 52. Therefore, in addition to the change of the presser foot 8, when the work cloth is changed, the presser pressure setting switch is set. By changing the target presser pressure by operating 52, the presser pressure can also be automatically adjusted according to the type of work cloth.

In the present invention, the target pressure can be set by the presser pressure setting switch 52. However, the target pressure is set by manually rotating the adjusting screw, and then the presser rod 4 is set.
When the height position changes, the drive motor 32 may be driven in accordance with the change amount to adjust the insertion amount of the adjustment screw 30 into the arm 2. In this case, a map representing the drive amount of the drive motor 32 using the amount of change in the height position of the presser bar 4 as an argument is stored in the ROM 50b, the drive amount of the drive motor 32 is obtained from this map, and the adjustment screw is adjusted. If the rotation of 30 is performed, the potentiometer 33 for detecting the insertion amount of the adjusting screw 33 into the arm becomes unnecessary, and the configuration of the device can be further simplified.

Further, in the present embodiment, the adjustment of the presser pressure is performed using the adjustment screw 30 as in the case of the conventional sewing machine.However, the present invention is not limited to this.For example, an electromagnetic solenoid or an air cylinder is used. The pressing pressure may be adjusted.

[Effects of the Invention] As described above in detail, in the presser foot device of the sewing machine of the present invention, the height of the presser bar when the presser foot is at the presser foot position changes with the change of the presser foot. By automatically adjusting the urging force of the presser bar by the presser spring, the pressurizing pressure of the work cloth can be controlled to a predetermined pressure. Therefore, it is not necessary to manually adjust the presser screw every time the presser foot is changed as in the related art, and the operability of the sewing machine can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a configuration of a presser pressure control system of the embodiment, FIG. 2 shows an entire configuration of the sewing machine, FIG. 2 (a) is a front view thereof, and FIG. 2 (b) is a left side thereof. FIG. 3 is a partial cross-sectional view showing the structure of the presser foot, FIG. 4 is an explanatory view illustrating a presser foot mounting portion of the presser foot support, and FIG. 5 is a presser pressure adjusting process executed by a control circuit. It is a flowchart showing. DESCRIPTION OF SYMBOLS 1 ... Sewing machine, 2 ... Arm, 3 ... Fabric presser 4 ... Presser bar, 8 ... Presser foot, 12 ... Presser foot support 23 ... Gear, 25 ... Drive device, 30 ... Adjustment screw 32 Drive motor, 43 Hall element 50 Control circuit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-155589 (JP, A) JP-A-2-85497 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) D05B 29/00-29/31 D05B 39/00

Claims (1)

(57) [Claims] A presser bar attached to an arm of a sewing machine so as to be able to move up and down and having a presser foot attached to a lower end thereof; and a presser spring for urging the presser bar downward to apply a predetermined pressure to the presser foot. A presser adjusting member that adjusts the pressure applied to the presser foot when the presser foot is at the presser foot position by adjusting the biasing force of the presser spring. Detecting means for detecting the height position of the presser bar when the bar is at the lowered position and the presser foot is at the cloth presser position; and the presser foot based on the height position of the presser bar detected by the detector means. An adjusting member drive control means for driving an adjusting member to control a pressure applied to the presser foot to a predetermined pressure when the presser foot is at the presser foot position; and a cloth presser device for a sewing machine. .