JPH04309399A - Needle thread tension controller of sewing machine - Google Patents

Abstract

PURPOSE:To constitute the controller so that troublesomeness of tension control of a needle thread by a thread tension device is obviated, tension of the needle thread is always adjusted automatically to an optimum value, and homogeneous sewing being free from uneven sewing can be executed. CONSTITUTION:Setting information of needle thread tension corresponding to cloth thickness or the number of overlap pieces of cloth of an object to be sewn is stored in advance together with data of a sewing pattern, and when automatic sewing is executed by reading out the data of its sewing pattern, the setting information of the needle thread tension is also read out, and in accordance with its setting information, one piece or plural pieces in thread tension devices 11-14 whose thread inserting/holding force is different in a thread tension device unit 10 are validated selectively, and tension given to the needle thread is adjusted automatically.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is a sewing machine that uses top and bottom threads to form lock stitches and chain stitches. Regarding a control device.

0002

[Prior Art] A lower thread and an upper thread are used for sewing with a sewing machine. The lower thread is wound around a bobbin and loaded into a bobbin case that is locked in a hook, and is fed out for each stitch. When the bobbin is pulled out from the bobbin case, tension is applied by the clamping force of the leaf spring and the rotational inertia of the bobbin, which has mass.

On the other hand, the needle thread is let out from a spool set on the outside of the main body, passes through a thread guide, is held by the tension plate of a thread tension device, and is then passed through a hole in a thread take-up lever and into a hole at the tip of a sewing machine needle. Each stitch is pulled out by the vertical movement of the thread take-up, and at this time tension is applied by the clamping force of the thread tension plate by the spring of the thread tension device.

If the tension of the upper and lower threads is too strong, puckering (seam wrinkles) will occur, if it is too weak, chochin (poor thread tightness) will occur, and if the tension is uneven, uneven stitching (the knot point of the seam will be on the top or bottom surface of the fabric). Therefore, it is necessary to always apply the optimum tension when sewing. Conventionally, this has been dealt with by manually adjusting the tension of the upper thread using a thread tension device.

[0005]

[Problems to be Solved by the Invention] However, in such conventional sewing machines, a thread tension controller is used to optimize the tension of the upper thread according to the thickness of the material, the number of overlapping sheets, etc. each time the material to be sewn changes. had to be readjusted manually, which was not only cumbersome but also difficult to make minute adjustments, which often made it impossible to adjust to the optimum value.

Furthermore, if there are parts in the sewing pattern for the same workpiece that have large differences in fabric thickness or the number of overlapping pieces of fabric, for example, if the sewing machine is installed in the center of a steering wheel of a car, it can be used instantly in the event of an accident such as a collision. When sewing an airbag that inflates to protect the driver from impact,
Various cut fabric parts are sewn together, but there are parts where the number of overlapping pieces of fabric is quite large and parts where it is small, making it extremely difficult to sew the entire piece evenly with a continuous sewing pattern.

The present invention has been made in view of the above points, and eliminates the troublesome adjustment of upper thread tension using a thread tension device, and also allows for adjusting the fabric thickness or fabric thickness within a sewing pattern for the same workpiece. To enable uniform sewing without uneven stitching by always automatically adjusting needle thread tension to the optimum value even if there are parts with greatly different numbers of overlapped sheets.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides means for storing needle thread tension setting information according to the fabric thickness of the workpiece or the number of overlapped fabrics together with sewing pattern data. , when the stored sewing pattern data is read out and sewing is performed, the setting information of the needle thread tension is also read out, and a thread tension device control that controls a thread tension device that applies tension to the needle thread according to the setting information. To provide an upper thread tension control device for a sewing machine comprising means.

[0009] Furthermore, a sensor may be provided to detect the thickness of the fabric of the object to be sewn or the number of overlapping pieces of fabric, and the thread tension device control means may control the thread tension device in accordance with the detected information. Each of the above needle thread tension control devices includes three or more thread tension devices, and the thread tension device control means selectively enables one or more of the thread tension devices to pinch the needle thread. It is better to make it .

Alternatively, a pneumatic thread tension device that clamps the upper thread using air pressure may be used as the thread tension device, and the thread tension device control means may electrically control the pressure of the air supplied to the thread tension device. You can also do this.

[0011]

[Operation] By using the needle thread tension control device of the sewing machine configured as described above, the thread tension controller control means adjusts the current cloth pressure or cloth according to the needle thread tension setting information read together with the sewing pattern during automatic sewing. The thread tension device is controlled so that the tension suitable for the number of overlapping sheets is obtained. Alternatively, the thread tension device control means controls the thread tension device according to information about the fabric thickness of the workpiece or the number of overlapping pieces of fabric detected by the sensor from before to the end of the series of sewing,
Always give optimum tension to the upper thread.

[0012] Therefore, there is no need to manually adjust the thread tension device according to the object to be sewn, and even if the sewing pattern for the same object contains parts with large differences in fabric thickness or number of overlapped fabrics, Since the needle thread tension is always automatically adjusted to the optimum value, uniform sewing without uneven stitching is possible.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing an example of the external appearance of a sewing machine equipped with a needle thread tension control device according to an embodiment of the present invention.

In FIG. 1, 1 is a sewing machine body, 2 is a bed, and 3 is a needle bar having a sewing machine needle 4 fixed to its lower end and moving up and down in conjunction with a main shaft (not shown). There is an X on bed 2
, a movable body 5 that moves two-dimensionally in the Y direction is provided, and a cloth holder 6 in the shape of a substantially rectangular frame is attached to the distal end of the movable body 5, so that the needle drop point is within the frame. This moving body 5 is
When this sewing machine is started, the workpiece held in the fabric holder 6 is moved by an unillustrated XY moving mechanism equipped with an Move the needle drop point of the fabric along the sewing pattern.

A thread tension regulator unit 10 is provided at the front of the upper part of the sewing machine body 1, and there are four thread tension regulators 11 to 14 installed therein.
are arranged horizontally in a row and covered with a cover 15, leaving only each knob part c exposed. Then, the upper thread 7 is let out from a spool (not shown) set outside the main body, and the thread guides 16, 1
7 to the thread tension device unit 10, and as shown in FIG.
and the thread tension plate b (receiver plate), and then guide the sewing machine needle 4 downward through the thread guide 18 and through the hole of the thread take-up which protrudes from the slit of the sewing machine body 1 and moves up and down in conjunction with the main shaft (not shown). Pass it through the hole at the tip of.

In this way, the upper thread 7 is pulled out by the vertical movement of the thread take-up lever 19 for each stitch, but at this time, the tension plates a, Tension is applied by the clamping force b. Although the bobbin thread is not shown, it is wound around a bobbin and loaded into a bobbin case that is locked in the hook, just like in a conventional sewing machine, and is fed out for each stitch and released from the bobbin case. drawn out.

Furthermore, a keyboard 20 is removably provided at the base of the sewing machine body 1, and the two are electrically connected by a connector or cord (not shown). This keyboard 20 includes a start switch 21, a preparation switch 22, a numeric keypad 23 for inputting numerical values, and a moving object 5.
It is equipped with a jog switch 24 consisting of four switches for moving the camera in the X and Y directions, and a display 25 for displaying input numerical values and the like.

Further, a floppy disk drive device (FDD) 27 having a floppy disk insertion slot 27a is provided below the keyboard 20, and the floppy disk drive device (FDD) 27 has a floppy disk insertion slot 27a. You can insert a floppy disk that stores information such as needle thread tension settings and read out the data, or use the keyboard 2 to read out the data.
Data created using 0 can be stored on a floppy disk.

The thread tension regulator unit 10 in this embodiment will now be explained in more detail with reference to FIGS. 2 and 3. The four thread tension devices 11 to 14 shown in FIG. 2 each have a knob c supported by a thread tension shaft (not shown).
By the coil spring interposed between and the thread tension plate a,
The thread tension disc a is pressed against the thread tension disc b to clamp the upper thread 7 and apply tension to it. It is adjusted and fixed so that it is the weakest and becomes stronger in order of 12, 13, and 14.

That is, each thread tension device 11, 12, 13,
The tension according to 14 is respectively tension■,■,■
, ■, the magnitude relationship is as follows. Tension■＜Tension■＜Tension■＜Tension■

[0021] Each thread tension device 11 is installed in the sewing machine main body 1.
As shown in FIG. There is. When this plate floating tool 31 is inserted between the thread tension plates a and b as shown in FIG. 4(A),
Since the thread tension discs a and b are separated, they are in an invalid (non-selected) state in which they do not clamp the upper thread 7. 4 (B)
), as shown in Fig. 2, when the thread tension discs are removed from between the tension discs a and b,
The thread tension disc a is pressed by the thread tension disc b to be in a valid (selected) state in which it clamps the upper thread 7.

Therefore, by controlling the air cylinder 30 for each of the thread tension devices 11 to 14, the tension applied to the upper thread can be changed depending on which thread tension device is activated.

The control system of this sewing machine will be explained with reference to FIG. In FIG. 5, CPU3, which is a central processing unit,
2. ROM 33 which is a program memory, RAM 34 which is a data memory, and I/O 35 which is an input/output section,
36 and a bus connecting these constitute a microcomputer that centrally controls the entire sewing machine.

The I/O 35 includes the keyboard 20 and FDD 27 described above, and a cloth thickness sensor 37 described later as necessary.
Input signals or data from The I/O 36 outputs control signals to various drive circuits, and the sewing machine motor drive circuit 38 controls the drive of the sewing machine motor 39 that rotates the main shaft of the sewing machine, and the pulse motor drive circuit 40 controls the driving of the sewing machine motor 39 as shown in FIG. The driving of the X pulse motor 41 and the Y pulse motor 42 of the XY moving mechanism for moving the movable body 5 is controlled.

Furthermore, the drive circuits 43a to 43d drive and control the electromagnetic valves 44a to 44d, and the pressurized air source 4
5 to each of the air cylinders 30a to 30d (corresponding to the air cylinder 30 shown in FIG. 3), the tray lifting device 31 is protruded or retracted, and the thread tension devices 11 to It is possible to select and enable one or more of the 14, and disable the others.

According to the sewing machine configured as described above, as is conventionally known, data of a required sewing pattern is created in advance as coordinate value data of each needle drop point and pitch data for each stitch. , can be stored in the floppy disk 28, and at this time, information on setting the needle thread tension according to the fabric thickness or the number of overlapping pieces of fabric in each part of the sewing object is also stored. be able to.

FIG. 6 shows the CPU 3 during sewing according to this embodiment.
This is a flowchart of the processing according to No. 2, and if the above-mentioned floppy disk 28 is inserted into the FDD 27 and the preparation switch 22 of the keyboard 20 shown in FIG.
is activated to read data from the floppy disk 28, load it into the RAM 34, and input the sewing pattern. At this time, setting information for the needle thread tension can also be input at the same time.

Then, when the cloth holder 6 shown in FIG. 1 holds the cloth as the object to be sewn and the start switch 21 is pressed, the sewing operation is started. That is, the CPU 32 controls the sewing machine motor drive circuit 3 according to the sewing data loaded into the RAM.
8 and pulse motor drive circuit 40 to operate the sewing machine needle 4, thread take-up 19, and other parts linked to the main shaft of the sewing machine, and to move the movable body 5 in the X and Y directions to sew a predetermined pattern.

At this time, first, the solenoid valves 44a to 44d are driven and controlled via the drive circuits 43a to 43d as described above based on the initial needle thread tension setting information, and the air cylinders 30a to 30d are operated to operate the thread tension regulator. The thread tension devices 11 to 14 in the unit 10 are selectively enabled, and the tension applied to the upper thread is adjusted to an optimum value according to the fabric thickness of the sewing part (needle drop part) or the number of overlapped fabrics.

[0030] Then, whether or not the tension change point has been reached,
That is, it is determined whether or not the upper thread tension setting information has changed, and if it has changed, the thread tension devices 11 to 14 are reselected in accordance with the setting information to automatically adjust the upper thread tension. In this manner, the tension applied to the upper thread is automatically adjusted in accordance with the setting information read out along with the sewing pattern data until the sewing end point, and when the sewing end point is reached, the sewing end process is performed and the operation is completed.

Therefore, as shown in FIGS. 7 and 8, for example, there is a rectangular cloth C1 cut from the same fabric, a slightly smaller rectangular cloth C2, and an even smaller rectangular cloth C3.
and a small circular cloth C4 are sequentially stacked on top of each other.
In the sewing pattern shown by the broken line in Figure 7, point A → point B → point C →
When sewing in the order of point A, the number of overlapping pieces of cloth in the sewing section is
It changes as follows. 1 piece → 2 pieces → 3 pieces → 4 pieces → 3 pieces → 2 pieces → 1 piece → 2 pieces → 1
The tension of the needle thread should be the same as mentioned above.
, ■, ■, ■ are preferably selected sequentially as follows, and this embodiment makes it possible. Tension■→■→■→■→■→■→■→■→■

00
32] In addition to changing the tension depending on the sewing pattern of the same sewing item, if the thickness of the fabric or the number of overlapping pieces of fabric differs for each sewing pattern, the tension may vary depending on the item to be sewn. If the thickness or the number of overlapping pieces of fabric differs, the tension of the needle thread can be automatically adjusted by selecting the thread tension devices 11 to 14 according to the needle thread tension setting information stored for each material to be sewn. can.

Alternatively, without loading the needle thread tension setting information from the floppy disk, the cloth holder 6 can be moved according to a desired sewing pattern by operating the jog switch 24 on the keyboard 20 of FIG.
using the numerical value (tension■ is the value 1, tension■
(such as the number 2), and the input data can also be stored on a floppy disk.

Furthermore, if a fabric thickness sensor 37 shown in FIG. 5 is provided to detect the fabric thickness near the needle drop point of the workpiece during sewing or the number of overlapping pieces of fabric, the needle thread tension can be determined in advance along with the sewing pattern. The needle thread tension can be automatically adjusted to the optimum value without having to memorize setting information. For example, in the case of a sewing machine that uses a normal presser foot, the cloth thickness sensor 37 changes the lowering position of the presser foot depending on the thickness of the cloth or the number of sheets of cloth of the same thickness. , a linear sensor such as a potentiometer can be used to detect it.

Alternatively, if the object to be sewn is a whitish thin cloth such as a Y-shirt, a transmission type photosensor can be used to first detect a piece of cloth and store the data. Using this as a standard, it is also possible to detect the number of overlapping pieces of cloth in real time during actual sewing.

By the way, in the above-mentioned embodiment, four thread tension regulators, four air cylinders, and four solenoid valves are used, but in order to be able to adjust the tension more finely, it would be necessary to use a larger number of these. Become. but,
The tension of the upper thread can be automatically adjusted as desired by simply using a pneumatic thread tension device that is equipped with an air cylinder and an air pressure adjustment device that adjusts the pressure of the air sent to the air cylinder. .

FIG. 9 is a block diagram of the pneumatic thread tension device and its control system. The pneumatic thread tension device 50 is constructed by fitting a thread tension shaft 51 into a support piece 1a that forms a part of the sewing machine body 1, and fastening it with a thread tension plate (receptacle) 52 integrally formed at the base thereof and a nut 54. Installed. In addition, the thread tension shaft 5
A thread insertion hole 55 through which the needle thread 7 is passed is formed at the base of the needle thread 1 . The thread tension shaft 51 is further inserted into a concave hole 53a of a conical thread tension disc (push disc) 53.
3 is loosely fitted so as to be slidable in the direction of the arrow.

Further, an air cylinder 57 is attached to a bracket 56 fixed to the support piece 1a, and the tip of its drive rod 58 is fixed to the top of the thread tension plate 53. The air pressurization port 5 of this air cylinder 57
9, by supplying pressurized air from the pressurized air source 45 through the air pressure adjustment device 60 and the pipe 61, the air cylinder 57 causes its drive rod 58 to protrude, thereby moving the thread tension disc 53 to the thread tension disc 52. the end surfaces 52a of both plates,
53a pinches the upper thread 7 to apply tension.

The air pressure regulating device 60 is configured as shown in FIG.
The pressure of the output air is changed linearly with respect to the voltage applied by the drive circuit 62 operated by the PU 32 in accordance with the control signal output from the I/O 36. Therefore, by controlling the drive circuit 62, the pressure of the air supplied to the air cylinder 57 can be controlled steplessly, and thereby the clamping pressure on the upper thread 7 by the thread tension discs 52 and 53, that is, the magnitude of the tension applied, can be arbitrarily controlled. can be adjusted to Note that the air pressure adjustment device 60 used here
For example, a known type may be used, such as one using a piezoresistor or an electromagnetic coil type using a moving coil and a diaphragm.

[0040]

[Effects of the Invention] As explained above, according to the present invention, the tension of the needle thread in the sewing machine is always automatically adjusted to the optimum value according to the thickness of the material to be sewn or the number of overlapping layers of the material. , eliminates the trouble of adjusting the needle thread tension using a thread tensioner, and even if the sewing pattern for the same workpiece contains parts with different fabric thicknesses or different numbers of overlapped fabrics, uniform stitching without uneven stitching etc. can be achieved. This makes sewing possible. This effect is particularly great when sewing objects (for example, airbags) in which the sewing material is special and the number of overlapping layers of the material changes drastically.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the appearance of a sewing machine equipped with a needle thread tension control device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the internal configuration of the thread tension regulator unit in FIG. 1;

FIG. 3 is a plan view showing the relationship between the thread tension device and the dish lifting air cylinder.

[Figure 4] Similarly, the unselected (disabled) state and selected (disabled) state of the thread tension regulator
FIG. 3 is a perspective view for explaining a valid (valid) state.

FIG. 5 is a block diagram showing the configuration of a control system according to an embodiment of the present invention.

FIG. 6 is a flowchart of processing performed by the CPU 32 during sewing.

FIG. 7 is a plan view showing an example of a sewing object and its sewing pattern.

8 is a schematic cross-sectional view showing a cross section taken along the line DD in FIG. 7 with spaces between the cloths; FIG.

FIG. 9 is a configuration diagram showing an example of another means for adjusting the tension of the needle thread.

[Explanation of symbols]

1 Sewing machine body 2 Bed
4 Sewing machine needle 5 Moving body 6 Cloth holder 7 Needle thread 8 Sewing object 10 Thread tension device units 11 to 14 Thread tension device 15
Cover 16-18 Thread guide 19 Balance 20 Keyboard 27 FDD 28 Floppy disk 30, 30a-
30d Air cylinder 31 Dish lifting device 32 CPU
33 ROM 34 RAM 35,36 I
/O 37 Cloth thickness sensor 43a-43d Drive circuit 44a-44
d Solenoid valve 45 Pressurized air source 50 Pneumatic thread tension device 51 Thread tension shaft 52, 53 Thread tension disc 57 Air cylinder
60 Air pressure regulator 62 Drive circuit

Claims (4)

[Claims] 1. Means for storing sewing pattern data as well as needle thread tension setting information according to the fabric thickness of the object to be sewn or the number of overlapping pieces of cloth, and sewing by reading out the sewing pattern data stored in the means. The upper thread of the sewing machine is characterized by comprising: a thread tension controller that also reads the setting information of the upper thread tension and controls a thread tension controller that applies tension to the upper thread according to the setting information. Tension control device. [Claim 2] Consisting of a sensor that detects the fabric thickness of the object to be sewn or the number of overlapped fabrics, and a thread tension device control means that controls a thread tension device that applies tension to the needle thread in accordance with information detected by the sensor. An upper thread tension control device for a sewing machine, characterized in that: 3. The needle thread tension control device for a sewing machine according to claim 1 or 2, comprising three or more thread tension devices,
An upper thread tension control device for a sewing machine, characterized in that the thread tension controller is a means for selectively activating one or more of the thread tension controllers to clamp the upper thread. 4. The needle thread tension control device for a sewing machine according to claim 1, wherein the thread tension device is a pneumatic thread tension device that clamps the needle thread by air pressure, and the thread tension device control means controls the tension of the thread. An upper thread tension control device for a sewing machine, characterized in that the device is a means for electrically controlling the pressure of air supplied to a tension device.