JPH0560400B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention uses a feed dog for feeding a workpiece such as cloth at a constant pitch, and a presser foot provided opposite to the feed dog. The present invention relates to a presser foot device for a sewing machine that can sew a workpiece while transporting cloth or the like.

Conventional technology A conventional structure for holding a material to be sewn, such as cloth, with an appropriate force in a sewing machine that sews the material while conveying the material using the feed dog and the presser foot as described above. As shown in FIG. 13, there is a cloth plate 91 on which a cloth is placed, a feed dog (not shown) exposed at a predetermined interval on the surface of the cloth plate 91 to convey the cloth, and a feed dog on the feed dog. A presser foot 92 that presses the cloth, and a presser foot 94 that applies a predetermined force to the presser foot 92 provided at the tip of an arm 93 extending from the sewing machine body.
It is made up of more.

The aforementioned pressing section 94 includes a presser foot 95 that supports the presser foot 92, an adjustment screw 96 screwed onto the arm 93, and a shaft supported by the arm 93 so as to be slidable up and down and attached to the presser foot 95. Fitting presser bar 9
7, and a spring 98 inserted between the presser rod 97 and the adjustment screw 96.

Problems to be Solved by the Invention By the way, among the above-mentioned sewing machines, for example, overlock sewing machines that perform overlock stitches, especially those used for industrial purposes, perform sewing at a rate of several thousand to 10,000 times per minute. . Therefore, the feed dog must also feed the workpiece at the same speed.

However, in the above structure, as the speed of the feed dog increases, the impact on the opposing presser foot 92 becomes larger, and the presser foot 92 becomes floating, and the fabric etc. cannot be conveyed by the specified amount. I end up. On the other hand, in order to prevent this phenomenon, if the presser foot 92 is pressed with a force stronger than the specified value by tightening the adjustment screw 96, an abnormal load will be applied to the cloth, etc., causing damage. have

In addition, since the force with which the presser foot 92 presses the cloth etc. is set using the scale attached to the adjustment screw 96 as a guide, the force with which the presser foot 92 presses the cloth etc. is set as a guide. Even if the sewing machine is set on a scale, the pressing force may vary depending on the sewing machine, or the spring force may be insufficient, resulting in a problem that a predetermined pressing force cannot be obtained.

In view of the above-mentioned problems, the first object of the present invention is to provide a sewing machine that can detect and display the pressing force of the presser foot as a numerical value, and furthermore, automatically adjusts the pressing force to a set value based on the detection result. A second object is to provide a sewing machine that can be adjusted to

Means for Solving the Problems In order to achieve the above-mentioned first object, the present invention provides a method in which a presser foot provided for pressing a sewing workpiece against a feed dog that feeds the workpiece at a predetermined pitch. In the sewing machine which is supported in a resiliently biased state in the direction of the sewing material by a pressure adjustment mechanism, the pressing force adjustment mechanism includes an adjustment screw portion pivotally supported by an arm, and an end portion of the adjustment screw portion. comprising a pressure sensor attached to the presser foot, a display unit that displays the detected value of the pressure sensor as a numerical value, and a spring inserted between the pressure sensor and the presser foot, In order to achieve the second object, the pressing force adjustment mechanism includes an adjustment screw portion pivotally supported by an arm, and a motor for rotationally driving the adjustment screw portion via a gear provided on the adjustment screw portion. a pressure sensor attached to the end of the adjustment screw; a display unit that displays the detected value of the pressure sensor as a numerical value; a spring inserted between the pressure sensor and the presser foot; It is characterized by comprising a comparison and adjustment means that compares the detected value with a set value and corrects the pressing force to a prescribed pressing force if there is a difference.

Effect: According to the first and second means for achieving the above-mentioned objectives, the pressure sensor provided between the spring that applies a load to the presser foot that presses the cloth, etc. and the adjustment screw portion acts on the presser foot. The force is detected and the detected value is displayed as a numerical value on the display.

The comparison and adjustment means compares the detected value of the pressure sensor and the set value to determine the difference, and if there is a difference, corrects it to the specified pressing force, so that the presser foot always maintains a constant pressing force. can be attached.

Example An example of the present invention will be described below. FIG. 1 is a partially sectional perspective view of an overlock sewing machine as an embodiment of the present invention. In the figure, reference numeral 1 denotes an overlock sewing machine as an example of a sewing machine. Broadly speaking, this machine is comprised of a conveyor section 2 that carries cloth or the like to be sewn at a predetermined pitch, and a conveyor section 2 that carries the sewing material at a predetermined pitch. A cloth table 3 on which the fabric is placed, an arm 6 to which a pressing part 4 for pressing the cloth placed on the cloth table 3 with a predetermined force and a needle 5 for sewing are attached, and the needle 5 and the looper. The thread tension device 7 for adjusting the tension of each of the three threads S, and the aforementioned components such as the fabric table 3, arm 6, and thread tension device 7 are placed in optimal positions to operate each mechanism. It is composed of a sewing machine main body 8 that accommodates the sewing machine.

The cloth stand 3 provided on the left side of the sewing machine main body 8 is
A flat cloth plate 11 on which a cloth is placed is provided on the top, and a throat plate 12 is provided on the conveyance section side of the cloth plate 11. The feed dog is configured to appear and retract from the upper surface of the needle plate 12 at predetermined pitches as the needle 5 moves in order to convey the fabric as it is sewn.

The pressing portion 4 is provided on an arm 6 extending to a position facing the cloth table 3, and is configured to press the cloth from above the cloth plate 11. In this pressing section 4, a presser foot 14 for clamping the cloth between the feed dog and the feed dog is attached to the tip of a presser foot 15 that is arranged substantially parallel to the cloth plate 11, and the presser foot The stand 15 has a structure in which it is moved away from the feed dog by a drive unit 16 provided at the base when there is no need to press the cloth. A spring 17 for imparting elastic force to the presser foot 14 is attached to the intermediate portion of the presser foot 15 via a presser bar 18a. The other end of the spring 17 is provided with a pressure sensor 19 that can detect the pressing force via the auxiliary presser bar 18b, and a moving block 20 that supports the pressure sensor 19 on the back side. The moving block 20 is screwed into an adjustment screw 21 that is pivotally supported by the arm 6, and is regulated so as not to rotate by a guide body 22 provided on the inner wall of the arm 6. Accordingly, it is arranged to slide in the axial direction of the adjusting screw 21. Therefore, when the adjusting screw 21 is screwed in, the movable block 20 is pushed downward, and the amount of compression of the spring 17 increases, so that the elastic force becomes stronger and the pressing force of the presser foot 14 via the presser foot 15 increases. On the other hand, if you want to weaken the pressing force, reverse the adjustment screw 21 and the spring 17
The elastic force of is weakened, and the pressing force is reduced.

Further, a gear 23 is integrally provided on the adjustment screw 21, and meshes with a gear 25 provided on the output shaft of a DC motor 24 attached to the inner wall of the arm 6 to drive the DC motor 24. Accordingly, the adjustment screw 21 can be rotated.

Furthermore, as shown in FIG. 2, two 7-segment display devices are provided in order to convert the value detected by the pressure sensor 19 into a pressing force (Kg) and display it by a control device, which will be described later. indicator 2
7, and an increase switch 28 that increases or decreases the pressing force.
A display section 31 is provided, which includes a mode changeover switch 29 and a set switch 30, both of which have built-in LEDs. The numerical value displayed on the display 27 is
It displays the force applied to the presser foot 14, and is configured so that the force applied to the feed dog can always be displayed even if the size of the presser foot 14 is different.

As shown in FIG. 3, the control device 33 for converting the detected value of the pressure sensor 19 into a numerical value and for driving the DC motor 24 is executed by a CPU 34,
It is composed of a ROM 35, a RAM 36, a data bus 37, and an interface 38. The pressure sensor 19 is connected to the interface 3 via an amplification amplifier 39 and a digital signal converter 40.
8, as well as the aforementioned display 27, each switch 28, 29, 30, and DC motor 24.
is also connected to the CPU 34 via an interface 38.

The operation of the control device 33 will be explained with reference to the flowchart shown in FIG. First, presser foot 1
The mode changeover switch 29 is used in step S1 to determine whether the pressing force of 4 is to be adjusted automatically (AUTO) or manually (MANUAL).
The determination is made by detecting the ON-OFF state of .
In the case of automatic adjustment, the mode changeover switch 29 is turned on and the LED 29a lights up.
Set to AUTO mode, processing starts at step S2
The current data stored in the RAM 36 is displayed. Next, in step S3, it is determined whether or not the set switch 30 is turned on.
If it is not turned on, it is assumed that there is no change in the pressing force, and the process advances to step S4 to convert the analog signal detected by the pressure sensor 19 into a digital signal and input it into the CPU 34. Next, the pressing force is calculated and stored based on this digital signal (step S5), and compared with the data currently being displayed (step S6). As a result, if there is a difference, the process proceeds to step S7, where the DC motor 24 is rotated and the pressing force of the presser foot 14 is adjusted. If no difference occurs in step S6, there is no need for adjustment by the DC motor 24, so the process returns to step S2 and continues this process.

If you want to change the setting value of the pressing force during this automatic adjustment operation, press the set switch 30 on the display section 31.
Turn it on. Then, the set switch 30
When the LED 30a lights up, the process advances from step S3 to step S8. In step S8, operation of the increase switch 28a and decrease switch 28b of the display section 31 is permitted, and the data being displayed is changed by these operations. Then, the process returns from step S9 to step S8 until the set switch 30 is turned on again, and when the set switch 30 is turned on again, the LED 30b disappears and the process proceeds to step S4 and onwards, and the process changes based on the changed data. The pressing force of the presser foot 14 is changed.

When adjusting by manual operation, step
When the mode changeover switch 29 is turned off in step S1, the LED 29a disappears and the process proceeds to step S11 for manual adjustment. In step S11, the operator is permitted to manually rotate the adjustment screw 21, and input a desired pressing force value through these operations. Then, the analog signal detected by the pressure sensor 19 is converted into a digital signal.
The pressing force is calculated and stored based on this digital signal (step S13), and the current data is displayed on the display 27 (step S14).

Next, a thread tension device 7 for applying tension to the thread for the needle 5 and the looper is provided on the upper part of the sewing machine body as shown in FIG.
A, an upper looper thread tensioner 7B, and a lower looper thread tensioner 7C.

Each thread tension device 7A, 7B, 7C presses a pair of thread tension discs 51, 52 by the elastic force of a spring 53, and clamps the thread S inserted between them by the pressure contact force. A predetermined tension is applied to. One of the pair of thread tension plates 51 and 52 is attached to a support disk 56 supported by the other end of a bracket 55 screwed to a casing 54 of the sewing machine body 8. The other thread tension disc 52 is supported by a bowl-shaped disc holder 57 to which one end of a spring 53 is engaged.

As shown in FIG. 5, a rod-shaped member 59 that rotatably supports one end of a thread tension rod 58 is fixed to the bracket 55. As shown in FIG. The countersunk holder 57 is slidably inserted into the rod-shaped member 59 and the tension rod 58. The thread tension rod 58 is rotatably supported by a shaft bearing member 60 within the casing 54 of the sewing machine main body 8, one end is supported by the aforementioned rod-shaped member 59, and the other end is connected to a step motor 62 via a coupling ring 61. . Also, thread tension rod 58
A screw 58a is formed around the periphery of the spring 53, and a moving block 63 for receiving one end of the spring 53 is screwed into the screw portion. Block 63 is casing 54
A regulation block 65 provided on the inner wall prevents rotation, and as the tension rod 58 rotates, the tension rod 5
It is designed to slide in the axial direction of 8.
This movement of the moving block 63 changes the amount of compression of the spring 53, which causes the thread tension plate 5 to change.
1,52 adjusts the tension value acting on the thread. The position of the moving block 63 where the amount of compression of the spring 53 is the smallest is called the zero point position,
This position is detected by a position detection sensor 64 such as a photo cell provided below.

The step motor 62 is driven by a system shown in FIG. 6, and adjusts the tension acting on the threads of the thread tension discs 51, 52 to a predetermined amount. In Figure 6, 66 is CPU, 67 is ROM, 68 is RAM,
69 is an interface, and 70 is a data bus that connects these circuits. Note that the above configuration can also be used in common with the CPU 34, interface 38, etc. described above. 71 is a step motor 62
72 is a switch, and 73 is a display. Data is stored in the RAM 68 in the state shown in FIG. In the figure, D1 is an area for storing data for display eyes, and D2 is an area for storing combinations of pattern numbers and tensions of each thread tension regulator 7A to 7C. The column shows the tension value of the thread tension device 7A, and the third column shows the tension of the thread tension device 7B.
The fourth column shows the tension of the thread tension device 7C. D3 is an area for storing the final tension value, and D4 is an area for storing the tension value before change during real-time operation.

The switches 72 and display 73 are arranged on an operation panel 75 as shown in FIG.
In the figure, numeral 76 is a display section that displays the tension value acting on the yarn, and has two 7-segment display devices. 77 indicates which thread tension device 7A, 7B, 7 the tension displayed on the display section 76 is.
C, or its number is the thread tension controller display section that displays it. 78 is each thread tension device 7A, 7B, 7
Figure 7 shows the combination of C tensions.
This is a pattern display section for displaying a pattern number determined from the RAM table. This display section 78
The display section 77 is also composed of the same 7-segment display element as the display section 76. 79a is a switch for changing the pattern number in the increasing direction, and 79b is a switch for changing it in the decreasing direction. By operating these two switches 79a and 79b, the pattern number displayed on the display section 78 is desired. can be changed to the value of 80a is a switch for increasing the thread tension controller number displayed on the display section 77; 80b is a switch for decreasing it; 81a and 82a are for increasing the tension value displayed on the display section 76. Switches 81b and 82b for changing the direction are switches for changing the direction to decrease. 83 is the start switch, 84
is a set switch with a built-in LED, and each of the switches 79a, b, 80a, b, 81a, b, 8
When the lever set switch 84 is pressed before operating 2a and 2b, the pattern number, thread tension controller number,
Tension values can be changed and stored in memory. 8
5 is a mode conversion switch, and by operating this switch, the sewing machine can be changed between a preset mode and a real-time mode as described later.

FIG. 9 is a flowchart illustrating the operation of the system of FIG. 6. In the figure, the flow surrounded by the broken line is the preset mode, and the flow outside the broken line is the real-time mode.

When the power is turned on now, the tension at the time the power was turned off is read out and displayed in step S21, and the tension is applied to each thread tension device 7A, 7B, and 7C. In this case, the tension is applied by first rotating the step motor 62 in the reverse direction to return the moving block 63 to its origin, and then applying a predetermined number of normal rotation pulses to rotate it in the normal direction. Since the RAM 68 is backed up when the power is turned off, the tension stored in area D3 in the RAM when the power is turned off is retained even when the power is turned off, and when the power is turned on, the tension is
It is also written in the DISPPLAY area D1, and the display section 76
will be displayed at The movement of data within the RAM in this case is shown in the first row of FIG.

Next, in step S22, switches 79a, 79
When a pattern or a thread tension device is selected by operating buttons 80a and 80b, the process proceeds to step S23, where the display contents of display sections 78 and 73 are changed accordingly. The second row of FIG. 10 shows the case where pattern 2 is selected. Next, mode selection switch 8
5. If the start switch 83 is pressed in step S26 without pressing any of the set switches 84, the process advances to step S27 and all thread tension devices 7A, 7B, and 7C are operated in the pattern being displayed. The movement of data in the RAM 68 at this time is as shown in the third row of FIG.
data is written to area D3. The above operations are performed by the mode selection switch 85 and the set switch 84.
Continues unless pressed. In this way, the thread tension device is set to the combination of tensions corresponding to the pattern number. Also, step
When the thread tension device number is selected in S22, the display section 76 changes the display content to the tension of the selected thread tension device.

Next, when the set switch 84 is pressed in step S25, the built-in LED lights up to notify that the pattern, tension, etc. can be changed. Then, when the operator operates a predetermined switch in step S28 to increase or decrease the pattern, thread tension device, and tension, the changed values are displayed in step S29. After completing the change operation, the operator presses the set switch 84 again to turn off the LED, and the process advances from step S30 to step S31.
The contents of the memory in the RAM 68 are updated to the changed data. Next, when the start switch 83 is pressed in step S26, the process proceeds to step S27, and the thread tension device is operated based on the updated data. During the above operation, the movement and rewriting of data in the RAM 68 is as shown in FIG. However, this figure shows an example in which the tension values of each thread tension device in pattern 2 are changed from 1, 2, 1 to 2, 3, 2. The above operation is called preset mode.

Next, in step S24, mode selection switch 8 is turned on.
When 5 is pressed, the flow shifts to real-time mode from step S32 onwards. In this mode
Area D1 in the RAM 68 is changed to an area for storing the DISPLAY display and the actual tension of the thread tension device, and area D3 is changed to a storage area for change data.
D4 is used to store data before modification.
Therefore, when the mode change switch 85 is pressed in step S24, the data in area D1 is also written in area D4 as shown in FIG. As mentioned above, area D1 not only displays DISPLAY but also stores the actual tension, so each thread tension regulator 7A,
7B and 7C immediately operate with a combination of tensions based on the pattern being displayed (step S32).
Furthermore, once the mode change switch 85 is pressed,
The LED 86 on the operation panel 75 lights up to notify the operator that it is in real-time mode.

Next, in step S33, switches 79a, b,
When the thread tension device and tension are increased or decreased by operating 80a, b, 81a, or b, the process advances to step S34, and the increased or decreased value is displayed. At this time,
In the RAM, the changed data (2, 1, 3)' is written in area D1 as shown in Figure 12, so the tension of the thread tension regulator is changed in real time to the tension value of the changed data (step S35). .
The changed data is also written in area D3.

In this way, after the tension has been adjusted to the desired tension by the operator, the mode selection switch 8 is turned on in step S36.
When 5 is pressed again, the data of the pattern being displayed is updated (step S37) and the real-time mode is ended.

Meanwhile, in step S36, the mode selection switch 85 is
NOW− in step S38 without pressing .
When BEFERE selector switch 88 is pressed, RAM68
The data in area D1 within is rewritten to the pre-update data (1, 1, 1) stored in area D4, the data is displayed based on this data, and the thread tension device is operated (step S39). Then, if the mode selection switch 85 is pressed in step S40, the data of the pattern being displayed returns to the data before change (step S41).
Exit real-time mode.

Also, in step S40, the mode selection switch 8
Proceed to step S42 without pressing 5 and proceed to NOW-
When BEFORE switch 88 is pressed, the RAM
The data stored in the area D3 is written into the area D1 in the thread 68 (step S43), and the thread tension device is changed to the tension of the data and operates in real time. In this way, in real-time mode, the tension of the thread tension regulator can be changed and adjusted in real time, and the two areas D3 and D4 in RAM can be adjusted in real time.
Since the data before and after the change is stored in
By operating the NOW-BEFORE changeover switch 88, the tension before the change can be restored at any time, and the tension can be switched to or changed to the most desirable tension value.

Effects of the Invention As described above, since the device of the present invention is equipped with a pressure sensor in the pressing force adjustment mechanism, it is possible to numerically display the force with which the presser foot presses the cloth, and to adjust the pressing force to the optimum value. It is possible to set. at the same time,
An apparatus equipped with a means for automatically correcting when a difference between a set value and a value detected by a pressure sensor occurs can always apply an optimal pressing force to the cloth. Therefore, even when sewing is performed at high speed, the presser foot is maintained at an optimal pressing force, which prevents lifting and allows sewing to be performed as specified, while also preventing damage to the fabric or other material to be sewn. Can be effectively prevented.

Further, even if there are variations in the spring force of the spring that applies pressing force to the presser foot, the pressing force to the presser foot can always be applied as specified.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional perspective view of an embodiment of the present invention, FIG. 2 is a front view of a display section of an embodiment of the present invention, and FIG. 3 is a configuration diagram of a control device of an embodiment of the present invention. , FIG. 4 is a flowchart for explaining the operation of the control device, FIG. 5 is a partial sectional view of the thread tension device of the present embodiment, FIG. 6 is a configuration diagram of the control device for the thread tension device, and FIG. 8 is a front view of the display for the thread tension device, FIG. 9 is a flowchart explaining the operation of the thread tension device control device, and FIG. Figures 1 to 12 show the RAM of the thread tension regulator control device of the embodiment.
FIG. 13 is a partially sectional perspective view of a pressing section of a conventional sewing machine. 1... Overlock sewing machine, 2... Conveyance section,
3...Cloth stand, 4...Press section, 7...Thread tension device, 8
... Sewing machine body, 14 ... Presser foot, 17 ... Spring, 19 ... Pressure sensor, 21 ... Adjustment screw, 24 ... DC motor, 31 ... Display section, 3
3...Control device.

Claims (1)

[Scope of Claims] 1. A presser foot provided for pressing the sewing object against a feed dog that feeds the sewing object at a predetermined pitch is elastically moved in the direction of the sewing object by a pressing force adjustment mechanism. In the sewing machine supported in a biased state, the pressing force adjustment mechanism includes an adjustment screw portion pivotally supported by an arm, a pressure sensor attached to an end of the adjustment screw portion, and a detection mechanism of the pressure sensor. A presser foot device for a sewing machine, comprising: a display unit that displays a value as a numerical value; and a spring inserted between the pressure sensor and the presser foot. 2 A presser foot provided for pressing the sewing material against a feed dog that feeds the sewing material at a predetermined pitch is elastically biased in the direction of the sewing material by the pressing force adjustment mechanism. In the supported sewing machine, the pressing force adjustment mechanism includes: an adjustment screw portion pivotally supported by an arm; a motor for rotationally driving the adjustment screw portion via a gear provided on the adjustment screw portion; a pressure sensor attached to the end of the adjustment screw, a display section that displays the detected value of the pressure sensor as a numerical value, a spring inserted between the pressure sensor and the presser foot, and a detection section of the pressure sensor. 1. A presser foot device for a sewing machine, comprising: a comparing and adjusting means that compares a value with a set value and corrects the pressing force to a prescribed pressing force if there is a difference. 3. The presser foot device for a sewing machine according to claim 1 or 2, wherein the display section has a structure that converts a numerical value detected by a pressure sensor into a pressing force and displays it. 4. The presser foot device for a sewing machine according to claim 2, wherein the motor of the pressing force adjustment mechanism is a DC motor.