JPH11333172A - Needle thread tension controller of sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the length of the needle thread end after cutting by controlling a drive means during a period from the end of sewing at least to cutting the needle thread by a thread cutting member in a sewing machine which actuate a thread tension regulator by a drive means to tension the needle thread. SOLUTION: A button hole sewing machine 1 is equipped with a needle 9 to move in vertical and lateral directions, a cloth presser 15 to press cloth, a cloth holding plate 14 to longitudinally move in the cloth feed direction, and a cloth cutting knife 16 to cut cloth and form a button hole. Also a thread tension regulator 19 to tension the needle thread, which is constituted so as to tension the needle thread by clamping the needle thread in between a pair of tension discs (fixed and movable discs) and continuously change the resistance during sewing by motion of a motion shaft and equipped with a needle thread tension voice coil motor to link with the motion shaft via a lever as a drive means to electrically drive the drive shaft, is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thread tension control device for a sewing machine for controlling the tension of an upper thread in order to shorten a thread end connected to a cloth.

[0002]

2. Description of the Related Art In a conventional buttonhole overlock sewing machine, a needle thread tension to be set by each sewing portion of a buttonhole overhole (parallel portions on both sides parallel to the buttonhole and bar-tacking portions at both ends of the buttonhole). Because the thread tension is different, two thread tensioners (one for the parallel part and one for the bar-tacking part) that are set to different thread tensions are provided for each sewing part, and only the thread tensioner corresponding to each sewing part is effective at the time of sewing. In order to make the other thread tensioner inactive, each thread tensioner is provided with a tension release mechanism (plate floating mechanism). This tension release mechanism
For example, a tension release cam connected to the mechanism is provided, and the cam is interlocked with a main cam for setting a sewing pattern to release the tension of one thread tensioner at a predetermined time. Since the main cam rotates in conjunction with the main shaft of the sewing machine, the main cam is set so as to make one rotation for the required number of stitches for forming a predetermined buttonhole, ie, the predetermined number of rotations of the main shaft of the sewing machine.

In a conventional buttonhole overlock sewing machine, an upper thread cutting mechanism for cutting an upper thread is used in accordance with an operation of a pedal or the like by a worker to raise a presser foot.
Before the presser foot rises, it slides near the needle hole above the presser foot, holds the upper thread between the cloth and the needle, holds it, and cuts it.
Then, there is known a mechanism having an upper thread cutting member that retreats to a standby position by sliding while holding the upper thread cutting end connected to the needle hole, so-called upper thread cutting scissors.

On the other hand, in a sewing machine in which the upper thread is cut above the cloth and then the lower thread is cut below the cloth, as in the above-mentioned buttonhole overlock sewing machine, for example, the length of the upper thread end connected to the cloth is made as short as possible. In order to do this, the upper thread end that has been cut when cutting the lower thread is drawn into the cloth. That is, as shown in the schematic diagram of FIG. 13, when the hand arm 202 preceding the moving knife 201 that cuts the lower thread L2 pulls the lower thread L2, the lower thread L2 is pulled and the upper thread L1 is put into the cloth CL. By pulling in, the cut end of the upper thread L1 does not remain on or protrude from the cloth, and the front (upper) side of the cloth is finished finely.

[0005]

However, in the conventional buttonhole overlock sewing machine, since the tension release mechanism is operated by controlling the cam by the main cam linked to the main shaft, the sewing machine presses the sewing machine up after the sewing is completed, and When the cutting process is performed, the sewing machine spindle is stopped, and the thread tension device cannot be released.

When the thread tensioner is not released, tension is applied to the upper thread, so that threading cannot be performed at the time of replacing the upper thread, or supply of the upper thread cannot be obtained when the needle descends at the start of sewing. This may cause the cut end side of the thread to fall out of the needle hole. For this reason, it is necessary to operate the tension release mechanism by acting on the cam before the main cam stops. However, when the tension of the thread tension controller is lost, the upper thread composed of fibers is loosened by being pulled out from the thread supply side due to the action of relaxing, and thereby the upper thread path connected to the needle and the cloth. Becomes longer.

Since the upper thread whose tension has been released before the thread trimming is slack, if the thread trimming is performed in this state, as shown in FIG. 12B, the thread end length of the cut upper thread L1 is reduced. It will be long. On the other hand, when cutting under tension, as shown in FIG. 12A, the length of the cut end is short because the yarn path is short.

According to the present invention, in a sewing machine having an upper thread cutting member for cutting an upper thread above a sewing object, the length of the upper thread end after cutting is maintained by maintaining the upper thread tension until the upper thread is cut. It is an object of the present invention to provide a thread tension control device of a sewing machine which can shorten the thread tension.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention according to claim 1 provides a thread tensioner for applying tension to an upper thread of a sewing machine, and an actuation of the thread tensioner by electric drive. A driving means capable of continuously changing the tension applied to the upper thread by the thread tensioner, and an upper thread for cutting the upper thread between the sewing object and the needle near the needle drop position above the needle plate A thread tension control device for a sewing machine, comprising: a cutting member; and controlling the drive means to apply tension to the thread tensioner after sewing is completed at least until the upper thread cutting member cuts the upper thread. The configuration was adopted.

According to the first aspect of the present invention, when the upper thread is cut by the upper thread cutting member, tension can be appropriately applied to the upper thread, so that the upper thread does not loosen when cutting the upper thread. The remaining length of the cut end of the upper thread that protrudes from the workpiece after cutting can be reduced. Also, in a sewing machine that cuts a lower thread after cutting an upper thread, the cut end of the upper thread is short, so that it is easier to pull the upper thread under the cloth when the lower thread is hand-rolled at the time of cutting the lower thread. Further, since the tension applied to the upper thread from the thread tensioner can be continuously changed by electrical control, an appropriate upper thread tension according to each sewing process can be applied, and at the time of thread trimming, In addition, a tension suitable for a thread trimming process different from the thread tension at the time of sewing can be applied, and beautiful stitches can be obtained in all processes. Furthermore, since it is based on electrical control, even when the operation of the upper thread cutting member is performed by operation of a pedal or the like, control for appropriately applying or disabling the upper thread tension other than during the sewing machine operation is performed. The upper thread can be reliably threaded at the time of replacement of the upper thread, the upper thread can be prevented from coming off, and the cut end of the upper thread can be shortened as described above, and the thread can be easily drawn under the cloth. By implementing the present invention on a so-called bird's nest countermeasure sewing machine other than a cycle sewing machine that is controlled by a cam such as a buttonhole boring sewing machine, the remaining length of the upper thread can be shortened. It is also useful for preventing the occurrence of bird nests.

Here, the thread tensioner is, for example, of a type which applies tension to a thread by sandwiching the thread between two tension plates,
There is a rotary tension or the like in which a yarn is arranged around a rotating plate and tension is applied to the yarn by the rotational resistance of the rotating plate. The driving means is, for example, a voice coil meter, a proportional solenoid,
As long as the drive amount can be continuously changed by electric control, such as a combination of an air piston and a proportional electromagnetic solenoid valve, any type can be used, and this continuous drive amount is applied to the thread tensioner. (For example, by continuously changing the pressing force of the rotating plate or by continuously changing the rotation resistance of the rotating plate), the resistance force applied to the yarn from the thread tensioner is continuously reduced. Can be changed.

According to a second aspect of the present invention, in the sewing machine thread tension control device of the first aspect, it is possible to input set value data of a resistance applied to the upper thread from the thread tensioner at the time of cutting the upper thread. The configuration is provided with a simple setting input means.

According to the second aspect of the present invention, since the setting of the upper thread tension applied from the thread tensioner at the time of cutting the upper thread can be changed, the type and thickness of the upper thread and the type of the sewing object can be changed. In accordance with sewing conditions such as thickness and thickness, it is possible to change the setting to the thread tension at the time of upper thread trimming which is adapted to these sewing conditions.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a perspective view showing an overview of a buttonhole sewing machine provided with a thread tension control device according to an embodiment of the present invention. The buttonhole sewing machine 1 holds the sewing machine needle 9 and the cloth therebetween, and moves the cloth forward and backward in the cloth feeding direction to feed the cloth.
5, an upper thread cutting scissor 80 for cutting the upper thread above the cloth holding plate 14 and the cloth presser 15, a cloth cutting knife 16 for cutting a cloth to form a button hole, and the like, and the sewing machine needle 9 moves up and down. At the same time, sewing is performed while reciprocating (needle swinging motion) in a direction substantially perpendicular to the cloth feeding direction. For example, as shown in FIG.
This sewing machine performs sewing with a bar-tacking portion B, a right parallel portion C, and a second bar-tacking portion D to form a buttonhole on a workpiece. The buttonhole sewing machine 1 includes a control device (FIG. 6) that controls the buttonhole sewing machine 1 and configures the thread tension control device of the present embodiment, and a thread tension device that is controlled by the control device. Thread tensioner (active tension) 19 and upper thread tension VC as a driving means
An M (voice coil motor) 60 and an operation panel 110 (FIG. 5) as setting input means are provided.

FIG. 2 shows the thread tensioner 19 and the needle thread tension VC.
It is sectional drawing which shows M60. The thread tensioner 19 applies a resistance (tension) to the upper thread by sandwiching the upper thread between a pair of tension discs (the fixed dish 67 and the movable dish 66), and operates the operation shaft 63 to perform the above-described operation during sewing. It is a thread tensioner (active tension) capable of continuously changing the resistance.
The thread tensioner 19 includes a base member 64 fixed to the arm 4 of the sewing machine, a hollow shaft 65, a fixed plate 67 fixed to the hollow shaft 65, and a movable plate 66 movably provided along the hollow shaft 65. And a coil spring 68 that presses the movable plate 66 against the fixed plate 67. The hollow shaft 65 further includes a contact piece 66 a integral with the movable plate 66, and a contact piece that moves along the hollow shaft 65. The operation shaft 63 that can be brought into contact with 66a is inserted.

The needle thread tension VCM 60 has a low operating inertia,
This is a voice coil motor having a linear characteristic in a relationship between current and driving force. The voice coil motor includes a plunger 61, a circular yoke 601 constituting a magnetic circuit, an outer pole 602, a center pole 603, and a compensating copper tube 605 around a permanent magnet. The driving force of the plunger 61 can be controlled at high speed and almost in proportion to the current value by controlling the amount of current supplied to the coil 606. . The plunger 61 of the upper thread tension VCM60 is
Via a lever 62 having a pin 62a in the middle as a fulcrum,
It is connected to the operation shaft 63 of the thread tensioner 19, and by continuously changing the driving force of the upper thread tension VCM60,
The pressing force of the movable plate 66 of the thread tensioner 19 is continuously changed, and the resistance applied to the upper thread from the thread tensioner 19 can be continuously varied.

FIG. 3 shows a main configuration diagram for moving the upper thread trimming scissors 80 of the buttonhole holing machine 1. FIG. 4 shows a diagram for explaining the operation of the upper thread trimming scissors 80. FIG.
(A) is a top view showing the state immediately before the upper thread cutting scissors cut the upper thread, (b) is a top view showing the state where the upper thread cutting scissors cut the upper thread, and (c) is the upper thread cutting scissors. Is a top view showing a state where the upper thread is held after cutting. Upper thread cutting scissors 8
Reference numeral 0 includes a fixed blade 86, a movable blade 87, a thread holding spring 90, and the like, as shown in FIG.

The movable blade 87 is fixed to a fixed blade 86 so as to be rotatable about a pin 88.
And a cam contact portion 87c protruding on the same member. The cam abutting portion 87c is used to open the scissor-opening cam 92.
When the fixed blade 86 is pressed against the fixed blade 86 by a predetermined amount in a predetermined direction in contact with the closing scissors cam 91, the movable blade 87 operates with respect to the fixed blade 86. The scissors opening cam 92 and the scissors closing cam 91 are fixedly attached to the cloth presser 15, and change the relative arrangement with the upper thread cutting scissors 80 by the forward and backward movement of the cloth presser 15. More specifically, when the upper thread trimming scissors 80 are retracted from the standby position (moved upward in FIG. 4), the cam contact portion 87c abuts against the scissors opening cam 92 and is pushed to open the movable blade 87. Then, in this state, the upper thread trimming scissors 80 advance (move downward in FIG. 4), and thereafter,
By moving to the right and sliding above the needle drop position, the upper thread enters between the movable blade 87 and the fixed blade 86,
Further, the cam contact portion 87c contacts the scissors-closed cam 91 and is pushed to close the movable blade 87, whereby the upper thread extending from the sewing needle 9 is cut.

The thread holding spring 90 is a plate spring for holding the upper thread after cutting between the movable blade 87 and holding the upper thread. After the sewing of one buttonhole buttonhole, it is possible to shift to the next buttonhole buttonhole state as it is.

The upper thread cutting scissors 80 are moved in the front-rear direction and the left-right direction, for example, just before the buttonhole is finished and the cloth holder 15 is raised, to perform the above-described thread cutting operation. The main configuration for moving the upper thread cutting scissors 80 is
As shown in FIG. 3, a scissors lever 81, a connecting shaft 83, a scissors arm 85 and the like are provided. The connecting shaft 83 is supported by a bearing 95 so as to be capable of linear movement in the axial direction and rotatable about the axis. According to the linear movement and rotation of the connecting shaft 83, the upper thread trimming scissor 80 moves back and forth and in the horizontal direction. Perform slide movement to. A scissor lever 81 is fixed to the connecting shaft 83, and the scissor lever 81 causes a linear motion and a rotating motion of the connecting shaft 83.

The scissors lever 81 is connected to, for example, a sewing machine pedal (or a solenoid or a pulse motor) via a link mechanism (not shown), and is driven forward by a driving force of the sewing machine pedal (or a solenoid or a pulse motor). (The sewing machine head side) and clockwise (CW in the figure)
(The direction in which the upper thread trimming scissors 80 are moved to the needle side). Further, springs 82 and 84 are connected to the scissor lever 81. By the action of these springs 82 and 84, when there is no driving force of the sewing machine pedal (or solenoid or pulse motor), the spring 82, 84 is retracted to a predetermined standby position. Then, it rotates in the CCW direction to a predetermined standby angle and stops. Further, a locking portion 8 is provided at one end of the scissor lever 81.
1a, the locking portion 81a is provided during the operation of the sewing needle 9.
The upper thread held by the upper thread cutting scissors 80 is easily caught in the seam while the sewing needle 9 is in operation.

FIG. 5 is a diagram showing an operation panel 110 provided on the buttonhole sewing machine 1. The operation panel 110
It is used for setting and inputting various sewing parameters, displaying set values and displaying errors in sewing control, and is provided, for example, on a sewing machine table on which the buttonhole sewing machine 1 is placed.

On the operation panel 110, a sewing key 131 for starting sewing and an LED (Li
gh Emitting Diode display unit 13
2, a selection key 133 for selecting an input mode, a pattern number display section 134 for displaying the input mode selected by operating the selection key 133 by lighting, a parameter number display section 135, and a 2-digit 7-segment display section. A mode display section 141, a parameter display section 142 including a 4-digit 7-segment display section, a minus key 143 for input parameter value "-1", a plus key 144 for input parameter value "+1", and a predetermined input parameter setting value A down key 145 for subtracting in units, an up key 146 for adding input parameter set values in predetermined units,
A set key 147 and the like for notifying the threading to the sewing machine needle 9 and the positioning of the shuttle are provided.

FIG. 6 is a block diagram showing a circuit configuration of the buttonhole sewing machine 1. As shown in the figure, a control device of the buttonhole sewing machine 1 has a CPU (Central).
Processing Unit) 100, RAM
(Random Access Memory) 102,
ROM (Read Only Memory) 101,
Y feed counter 103 for counting the rotation amount of each pulse motor, base line feed counter 104, needle swing feed counter 105, cloth cutting knife counter 106 for counting the number of driving of the cloth cutting knife, Y for driving each pulse motor
I / O for connecting the CPU 100 with the feed pulse motor driver 111, the baseline feed pulse motor driver 112, the needle swing pulse motor driver 113, the drivers of various sensors and drivers, the operation panel 110, and the like.
An interface 109, a sewing machine motor driver 115 for controlling the driving of the sewing machine motor 5 for driving the sewing machine, a sewing machine motor encoder 119 for coding the rotation amount of the sewing machine motor 5 as a rotation angle of the upper shaft 6, and a thread tensioner 19
Tension driver 120 for driving the upper thread tension VCM (voice coil motor) 60, the cloth presser 15
Presser-lift solenoid drive circuit 121 for driving the presser-lift solenoid 122 for raising the pressure, cloth-cutting knife lowering cylinder drive circuit 123 for driving the cloth-cutting knife lowering cylinder 30 for lowering the cloth-cutting knife 16, and predetermined interrupt conditions (each CP value based on the counter value indicating the rotation amount of the pulse motor, the cloth feeding position, the rotation angle of the upper shaft 6, etc.
It comprises an interrupt controller 108 for outputting an interrupt signal to U100.

The Y-feed pulse motor 20 includes a cloth holder 15
And the cloth holding plate 14 are moved in the Y direction. The baseline feed pulse motor 40 is a motor for changing the base line position of the sewing needle 9, and the needle feed pulse motor 41 is a motor for moving the needle amount of the sewing needle 9. The motor to change.

The sewing machine motor driver 115 has a needle position sensor 116 for detecting that the sewing needle 9 is at an upper position, a feeder for detecting the reference positions of the cloth holder 15 and the cloth holding plate 14 in addition to the sewing motor 5. Reference position sensor 11
7. A TG (tach generator) generator 118 for detecting the rotation angle of the upper shaft 6 is connected. The I / O interface 109 includes a control panel 110, a driver and a driving circuit of each driving unit, a knife lowering detection switch 34 for detecting the lowering of the cloth cutting knife 16, and a presser lowering detecting switch for detecting the lowering of the cloth presser 15. 28, a Y-feed origin sensor 26 for detecting a state where the cloth feed (the cloth presser 15 and the cloth holding plate 14) is at the origin position, a baseline feed origin sensor 57 for indicating that the base position of the needle swing mechanism is at the origin, a needle swing Needle swing origin sensor 5 indicating that the swing width of the mechanism is at the origin
8. Hold down switch 12 for instructing lowering of cloth holder 15
4, a start switch 125 for instructing the start of driving of the sewing machine motor 5 and the like are connected.

The CPU 100 inputs data from the operation panel 110, detection signals from various connected sensors, and receives signals via each driver according to a control program stored in the ROM 101 using a predetermined area of the RAM 102 as a work area. Controls various drive units. ROM101
In addition to the sewing process of executing buttonhole buttonhole sewing based on the sewing data input via the operation panel 110, the thread to be threaded on the thread tensioner 19 at the timing of cutting the upper thread, which is a feature of the present invention. Control data and control programs such as a setting input process for inputting various setting data such as a tension value from the operation panel 110 and a thread tension control process for thread trimming for controlling the thread tensioner 19 at the time of the upper thread cutting process are stored. Have been.

The buttonhole sewing machine 1 provided with the control device (thread tension control device) of this embodiment is configured as described above, and inputs various setting data from the operation panel 110 as shown below. The drive control of the buttonhole sewing machine 1 including the thread tension device is performed, and the buttonhole processing from the start of sewing to the cutting of the upper thread and the lifting of the cloth holder 15 is performed.

First, the items of the setting data input from the operation panel 110 will be described. FIG. 7 is a chart diagram of a data table showing data that can be input from the operation panel. The data contents that can be input from the operation panel 110 are as shown in the parameter table of FIG.

That is, the cloth cutting length data, the knife width data, which are the length data of each part of the sewing pattern of the buttonhole buttonhole,
Bar-tack length data, bar-tack width data, parallel section pitch data, bar-tack section pitch data, cloth cutting knife-1st bar-tack clearance data, cloth cutting knife-2nd bar-tack clearance data, Also, knife drop left / right position data indicating the amount of shift in the left / right direction of the knife drop position, active tension correction data indicating a correction value of the upper thread tension VCM 60 for applying tension to the thread tensioner 19, and thread tensioner 19 at each sewing timing. Parallel part tension data, bar-tacking part tension data, sewing start tension data, sewing end tension data, thread trimming tension data, cloth cutting knife size data, holding size data, and cloth cutting knife 16 And the like are sewing machine speed data at the time of scalpel drive indicating the sewing machine speed at the time of driving. Among the above data items, the "thread tension at thread trimming" of the item number "16" is a data item of the characteristic of the present invention. The thread tension device 19 can be hung.

When the user drives the buttonhole sewing machine 1, first, the above setting data is transferred to the operation panel 110.
Perform the setting input process to input from. Default data and previously input data are stored in advance in each data item to be input, and the user inputs and changes only data items that need to be changed. For each item of the setting data, setting range data indicating a range of data values that can be input corresponding to the item is stored in advance, and if data out of the setting range data is input, an error determination is made. Is being done. A plurality of sets of the above setting data can be registered in association with a sewing pattern number. When a user selects and calls an arbitrary sewing pattern number, a set of setting data corresponding to the number is read. Used for actual sewing control.

After the above-described setting input processing is completed, the cloth is set, and the sewing key 131 of the operation panel 110 is turned on to set the cloth as shown in FIG. Based on the sewing pattern thus performed, the sewing shown in FIGS.
During the sewing, a tension corresponding to the tension data value corresponding to each timing is applied to the thread tensioner 19 at each timing of the sewing process. That is, the set tension of the "sewing start tension" at the start of the sewing process shown in FIG.
The set tension of the "bar tack" at the time of sewing the first bar-tacking portion B shown in the same figure and the set tension of the "parallel portion tension" at the time of sewing the right parallel portion C shown in FIG. 2 When the bar-tacking section D is sewn, the set tension of the “bar-tacking section tension” is changed to the “sewing end tension” when sewing to the final needle drop position shown in the same figure.
Are applied to the thread tensioner 19 respectively.

When a desired buttonhole is formed by the above-described sewing process, finally, the "thread trimming tension" is set.
Is applied to the thread tensioner 19. Then, when a request for instructing the thread trimming process and raising the presser foot 15 is issued by, for example, a pedal operation of an operator, the above-described upper thread trimming is sequentially performed while the tension of the “thread trimming tension” is applied. The thread cutting process by the scissors 80 and the lifting drive of the cloth presser 15 are performed. Thereafter, the thread tension of the thread tensioner 19 is released, and the sewing process of one buttonhole buttonhole is completed. Note that the thread trimming process and the raising process of the cloth presser 15 may not be started based on a pedal operation, but may be started by, for example, a button operation or automatic control.

The processing procedure of the button holing process including the setting input process and the needle thread tension controlling process at the time of thread trimming performed by the control section of the button holing machine 1 will be described below in detail. FIG. 9 is a flowchart illustrating a general procedure of a button holing process performed by the control unit of the button holing machine. The buttonhole buttoning process is started when the buttonhole buttonhole sewing machine 1 is started, for example. When the buttonhole sewing machine 1 is started, first, in step S1, a subroutine process of an operation panel setting process is performed, and the process proceeds to step S2.

In step S2, it is determined whether or not the sewing key 131 of the operation panel 110 is on. If it is on, the process proceeds to step S3. If it is off, the process returns to step S1 to perform the operation setting process. repeat. Sewing key 1
When 31 is depressed and the process proceeds to step S3, a subroutine process of sewing data creation for calculating a sewing pattern and the like is performed in step S3, and the process proceeds to step S4. In step S4, for example, an error flag in the RAM 102 is read, and it is determined whether or not an error has been recorded in the previous step. If no error has been recorded, the process directly proceeds to step S6. In step S5, an error display corresponding to the display unit 140 of the operation panel 110 is performed, and the button buttonhole processing is interrupted.

In step S6, a signal for lowering the cloth presser 15 is output to the presser lifting solenoid drive circuit 121, and the flow advances to step S7. In step S7, Y
Based on fine movements of the feed pulse motor 20, the base line feed pulse motor 40 and the needle feed pulse motor 41, and the detection outputs of the Y feed origin sensor 26, the baseline feed origin sensor 57 and the needle feed origin sensor 58, a cloth feed mechanism is provided. Then, each origin search of the needle swing mechanism is performed, and the process proceeds to step S8. In step S8, the Y feed pulse motor 20, the baseline feed pulse motor 40, and the needle swing pulse motor 41 are driven so that the sewing needle 9 is positioned above the first needle drop position at the start of sewing. Transition.

In step S9, a signal for raising the cloth presser 15 is output to the presser raising solenoid drive circuit 121, and the flow advances to step S10. In step S10, it is determined whether the ON operation of the sewing key 131 has been performed, and
If it is on, the process proceeds to step S11. If it is off, the process returns to step S1. In step S11, it is determined whether or not the press switch 124 is on. If the switch is on, the process directly proceeds to step S12. If it is off, the process returns to step S10 to repeat the processes of steps S10 and S11. Hold down switch 1
If the presser 24 is pressed and the process proceeds to step S12, the detection output of the presser foot lowering detection switch 28 is read in the step, and if the presser foot 15 is raised, the process proceeds to step S13 and the output for lowering the presser foot 15 is output. Then, the process proceeds to step S15. If the presser foot 15 is lowered, the process proceeds to step S14, where an output for raising the presser foot 15 is output, and the process returns to step S10 again.

In step S15, the press switch 12
It is determined whether or not the on operation of No. 4 has been performed, and if it is in the on state, the process directly proceeds to step S16. Return. In step S16, it is determined whether or not the start switch 125 for instructing the sewing start has been turned on. If the start switch 125 has not been turned on and remains in the off state, the processing from step S15 is repeated. Then, control goes to a step S17. In step S17, the sewing machine motor 5 is turned on in accordance with the sewing data created in the sewing data creation process in step S3.
To perform sewing from the beginning to the end of one buttonhole buttonhole, drive of the cloth cutting knife 16, and a sewing process of applying a tension set to the thread tensioner 19 at each sewing timing. Move to S18.

In step S18, for example, the RAM 102
The error flag is read, and it is determined whether or not an error has been recorded in the previous step. If no error has been recorded, the process directly proceeds to step S19, and if an error has been recorded, the process proceeds to step S20. Operation panel 110
Is displayed on the display unit 140, and the button buttoning process is interrupted.

In step S 19, a signal corresponding to the setting data of “tension at thread trimming” input in the operation panel setting process of step S 1 and stored in the RAM 102 is output to the active tension driver 120, and the thread tension controller 19 To the thread trimming tension set above, and
Move to 21. In step S21, the upper thread cutting scissors 8
0 to cut the sewing thread, and then
Then, the thread trimming / lifting process for raising 5 is performed, and the process proceeds to step S22. In step S22, the detection output of the presser foot lowering detection switch 28 is read, and after confirming the rise of the cloth presser 15, the process proceeds to step S23, where a signal is output to the active tension driver 120 to reduce the tension of the thread tensioner 19. It is released, and then returns to step S10 and repeats the processing from step S10 again.

That is, steps S19, S21, S
By the process 23, the upper thread tension control process is performed at the time of thread trimming in which a preset thread trimming tension is applied to the upper thread during the upper thread cutting process by the upper thread trimming scissors 80.

FIG. 10 shows a step S1 of the general flow.
9 is a flowchart showing a processing procedure of a subroutine of an operation panel setting process, which is a setting input process performed in step (a). When this serve routine is called, first, in step S
At 31 it is determined whether the selection key 133 is on or off. If it is on, the selection number (value indicating the setting mode) stored in the RAM 102 is incremented by "1" at step S32, and the routine goes to step S33. However, if the selection key 133 is off, the process jumps to step S35. Step S33
Then, it is determined whether or not the value of the selection number stored in the RAM 102 has exceeded the maximum value.
In step 4, "0" is substituted for the selection number, and the routine goes to step S35. If not, the routine goes to step S35.

Then, in steps S35 and S37, a branching process is performed according to the selection number.
If the selection number is 1, the subroutine of the parameter change process (step S38) is performed, and then the subroutine of the operation panel setting process is terminated. Return to General Flow.

FIG. 11 is a flowchart showing a procedure of a subroutine of a parameter changing process performed in step S38 of the operation panel setting process of FIG. When the parameter change processing subroutine is called, first,
In step S41, the plus key 144 on the operation panel 110
Is determined whether or not is pressed, and if pressed, step S
At 42, the parameter number (the value indicating the setting item of the input data (FIG. 7)) stored in the RAM 102 is incremented by "+1", and the routine goes to Step S43. Is jumped, the process jumps to step S45. Step S
At 43, it is determined whether or not the value of the parameter number in the RAM 102 has exceeded the maximum value.
In step 4, "1" is substituted for the selection number, and the routine goes to step S45. If not, the routine goes to step S45. That is, in the processing of steps S41 to S44, the setting item to be input can be moved and selected in the “+1” direction.

Next, steps S45 to S48
Then, the same processing as in steps S41 to S44 is performed by "-
The process is performed in the "1" direction, and the process proceeds to step S49. In step S49, a process of changing the parameter value of the setting item designated by the parameter number in the RAM 102 using the up key 146 and the down key 145 is performed in the same manner as in steps S41 to S49. Then, the process proceeds to step S50, in which the RAM
It is determined whether or not the parameter number in 102 is a number for setting the tension of the thread tensioner 19, and if so, step S
The routine proceeds to 51, where the tension of the setting data is output to the thread tensioner 19, and this subroutine processing is terminated. If it is not the setting item number of the tension data, the subroutine process is terminated as it is, and the process returns to the operation panel setting process of FIG.

The subroutine of the operation panel setting process and the parameter changing process described above is a general flow (FIG. 9).
In steps S1 and S2, the sewing is repeatedly performed at high speed until the sewing key 131 is pressed.
All setting data can be input.

As described above, according to the control device (thread tension control device) of the buttonhole buttonhole sewing machine 1 of this embodiment, the upper thread trimming is performed in the processes of steps S19 to S23 of the general flow (FIG. 9). Since the upper thread tension is appropriately applied when cutting the upper thread by the scissors 80, the slack of the upper thread at the time of cutting the upper thread is eliminated, and the remaining length of the upper thread coming out of the sewing material after cutting can be shortened. In addition, the thread tensioner 19
Since the tension applied to the upper thread can be controlled in a continuous amount by electrical control, it is possible to apply a thread tension suitable for thread trimming processing different from the thread tension during sewing at the time of thread trimming processing. Thereby, beautiful sewing at the end of sewing can be performed. Also, since the configuration for changing the tension of the thread tensioner is a configuration based on electrical control, even when the operation of the upper thread cutting scissors is performed based on a pedal operation or the like other than the sewing operation, The upper thread tension VCM 60 is driven in conjunction with an operation other than the sewing operation to apply a thread tension.

Further, the setting of the upper thread tension applied from the thread tensioner at the time of the upper thread cutting process can be changed by the operation panel setting process performed in step S1 of the general flow (FIG. 9). Depending on the sewing conditions such as the type and thickness of the sewing object, the thread tension at the time of upper thread trimming that is adapted to these sewing conditions can be changed.

In this embodiment, the upper thread cutting scissors 8
Although the thread trimming tension is applied from the start to the end of the drive of 0, the thread trimming tension is applied at least between the time when the upper thread trimming scissors 80 is applied to the upper thread and the time when the upper thread is cut. By doing so, the same effect as described above can be obtained. Further, in this embodiment, a tension disc type is exemplified as the thread tensioner, but a rotary tension or another type may be used. Further, the driving means is not limited to the voice coil meter, and may be any means such as a proportional solenoid, a combination of an air piston and a proportional electromagnetic solenoid valve, as long as the driving amount can be continuously changed by electric control. good. Further, in this embodiment, an example is shown in which the thread tension device of the present invention is applied to a buttonhole sewing machine, but may be applied to a cycle sewing machine such as a button sewing machine or an embroidery sewing machine, or other sewing machines. .

[0050]

According to the first aspect of the present invention, the upper thread is not slackened when the upper thread is cut, and the remaining length of the cut end of the upper thread that protrudes from the workpiece after cutting can be shortened. Also, in a sewing machine that cuts a lower thread after cutting an upper thread, the cut end of the upper thread is short, so that it is easier to pull the upper thread under the cloth when the lower thread is hand-rolled at the time of cutting the lower thread. Further, since the tension applied to the upper thread from the thread tensioner can be continuously changed by electrical control, an appropriate upper thread tension according to each sewing process can be applied, and at the time of thread trimming, ,
A tension suitable for thread trimming processing different from the thread tension at the time of sewing can be applied, and beautiful stitches can be obtained in all processes.
Furthermore, since it is based on electrical control, even when the operation of the upper thread cutting member is performed by operation of a pedal or the like, control for appropriately applying or disabling the upper thread tension other than during the sewing machine operation is performed. The upper thread can be reliably threaded at the time of replacement of the upper thread, the upper thread can be prevented from coming off, and the cut end of the upper thread can be shortened as described above, and the thread can be easily drawn under the cloth. By reducing the length of the upper thread cutting end by providing the same thread cutting member, thread tensioner, and driving means as in the present invention on a so-called bird nest countermeasure sewing machine, the present invention is implemented. Therefore, it is also useful for preventing the occurrence of bird nests.

According to the second aspect of the present invention, the setting and inputting means can change the setting of the upper thread tension applied from the thread tensioner at the time of the cutting process of the upper thread. According to the sewing conditions such as the type and thickness of the sewing product, the setting can be changed to the thread tension at the time of the upper thread trimming which is adapted to these sewing conditions.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the appearance of a buttonhole sewing machine provided with a thread tension control means according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a thread tensioner and a driving means of a thread tension device provided in the buttonhole overlock sewing machine.

FIG. 3 is a configuration diagram showing a main configuration for moving the upper thread cutting scissors of the buttonhole holing machine.

4 (a) is a top view showing the state immediately before the upper thread cutting scissors cut the upper thread, and FIG. 4 (b) is a top view showing the state immediately before the upper thread cutting scissors cut the upper thread. Is a top view showing a state in which the upper thread has been cut, and (c) is a top view showing a state in which the upper thread cutting scissors are holding the cut upper thread.

FIG. 5 is a view showing an operation panel provided in the buttonhole holing machine shown in FIG. 1;

FIG. 6 is a block diagram illustrating a circuit configuration of the buttonhole sewing machine.

FIG. 7 is a chart diagram of a data table showing data that can be input from the operation panel.

FIG. 8 is a view showing a sewing pattern of buttonhole buttonhole sewing performed by the buttonhole buttonhole sewing machine.

FIG. 9 is a flowchart illustrating a general procedure of a button holing process performed by a control unit of the button holing machine.

FIG. 10 is a flowchart showing a processing procedure of a subroutine of an operation panel setting process in the general flow of FIG. 9;

11 is a flowchart showing a procedure of a subroutine of a parameter changing process during the operation panel setting process of FIG. 10;

FIGS. 12A and 12B are front views showing a state in which the upper thread is cut in the upper thread cutting process, wherein FIG. 12A is a case where tension is applied to the upper thread, and FIG. It shows the case where it has not been done.

FIG. 13 is a view showing the pulling-in of the upper thread at the time of cutting the lower thread, which is conventionally performed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Buttonhole sewing machine 9 Sewing needle 14 Cloth holding plate 15 Cloth retainer 19 Thread tensioner 60 Upper thread tension VCM (Drive means) 80 Upper thread cutting scissors 81 Scissors lever 83 Connecting shaft 85 Scissors arm 86 Fixed blade 87 Movable blade 87c Cam Contact portion 90 Thread holding spring 91 Scissor closing cam 92 Scissor opening cam 100 CPU (control means) 110 Operation panel (setting input means)

Claims (2)

[Claims] 1. A thread tensioner for applying tension to an upper thread of a sewing machine, and a tension applied to the upper thread by the thread tensioner by being electrically actuated to act on the thread tensioner. A thread tension control device for a sewing machine, comprising: a driving means for cutting the upper thread between the sewing object and the needle in the vicinity of the needle drop position above the needle plate. A thread tension control device for a sewing machine, characterized in that the drive means is controlled to apply tension of a thread tensioner at least until the upper thread cutting member cuts the upper thread. 2. The sewing machine according to claim 1, further comprising setting input means for inputting set value data of resistance applied to the upper thread from the thread tensioner at the time of the cutting process of the upper thread. Thread tension control device.