JP2008237706A - sewing machine - Google Patents

Abstract

An object of the present invention is to provide a sewing machine that can change the output torque of a pulse motor in accordance with the thickness of the yarn and can suppress defective yarn trimming.
A sewing machine includes a thread trimming mechanism, a pulse motor, a pulse output means for inputting a command pulse to the pulse motor, and a command pulse detecting means for detecting a command pulse inputted to the pulse motor. Output pulse detecting means 3 for detecting an output pulse from the pulse motor, a load torque calculating means 43 for calculating a phase difference between the detected command pulse and the output pulse, and calculating the phase difference as a load torque, and a pulse motor The thickness judgment threshold value storage means 44 for storing the load torque threshold value, and when the calculated load torque is larger than the stored load torque threshold value, the driving speed of the pulse motor is reduced and the output torque is reduced. Drive control means 45 for increasing.
[Selection] Figure 4

Description

  The present invention relates to a sewing machine including a thread cutting mechanism that cuts a thread passed through a needle.

A sewing machine having a thread trimming mechanism for cutting a thread passed through a needle after completion of sewing has been proposed and put into practical use. In such a sewing machine, the thread trimming mechanism is connected to a pulse motor, and when the pulse motor is driven, the movable knife provided at the tip operates, and the thread is sandwiched between the movable knife and the fixed knife to cut (for example, , See Patent Document 1).
JP 2003-326064 A

Conventionally, the pulse motor is driven at a constant torque and at a constant rotational speed during thread trimming. Therefore, when the yarn to be cut is thick, the yarn may not be cut completely due to insufficient torque of the pulse motor. Therefore, it is necessary to provide a relatively large pulse motor in consideration of cutting a thick thread.
In addition, when thread trimming is performed with the needle inadvertently lowered, there is a problem that the movable knife touches the needle and needle breakage occurs. Conventionally, the thread trimming mechanism can be operated regardless of the position of the needle. Therefore, the user has a trouble of confirming the position of the needle at the time of thread trimming.

Accordingly, the present invention has been made to solve the above-described problems, and provides a sewing machine that can change the output torque of a pulse motor in accordance with the thickness of the yarn and suppress defective thread trimming. The purpose is to do.
Another object of the present invention is to provide a sewing machine that can prevent needle breakage even when thread trimming is performed with the needle lowered.

  The invention according to claim 1 is a sewing machine, wherein a thread trimming mechanism for cutting a thread passed through a needle below a needle plate, a pulse motor serving as a drive source for operating the thread trimming mechanism, and the pulse In driving the motor, pulse output means for inputting a command pulse to the pulse motor, command pulse detection means for detecting a command pulse input from the pulse output means to the pulse motor, and output pulses from the pulse motor The output pulse detection means to detect, the phase difference between the command pulse detected by the command pulse detection means and the pulse detected by the output pulse detection means is calculated, and this phase difference is calculated as the load torque applied to the pulse motor Load torque calculation means to determine whether the thread passed through the needle is thicker than the reference thickness or not A thickness judgment threshold storage means for storing a load torque threshold applied to the pulse motor, and a load torque calculated by the load torque calculation means from a load torque threshold stored in the thickness judgment threshold storage means Drive control means for decelerating the drive speed of the pulse motor and increasing the output torque.

According to the first aspect of the present invention, the thread trimming operation is performed by operating the thread trimming mechanism by driving the pulse motor. At this time, the command pulse detecting means detects a command pulse input from the pulse output means to the pulse motor. The output pulse detection means detects the output pulse of the pulse motor driven by the command pulse.
When the command pulse and the output pulse are detected, the load torque calculating means calculates the phase difference between the command pulse detected by the command pulse detecting means and the pulse detected by the output pulse detecting means, and applies this phase difference to the pulse motor. Calculated as load torque.
When the load torque calculated by the load torque calculation unit is larger than the load torque threshold stored in the thickness determination threshold storage unit, the drive control unit decelerates the drive speed of the pulse motor and outputs the output torque. Increase.
As a result, the load torque calculated by the load torque calculation means is larger than the load torque threshold stored in the thickness judgment threshold storage means, in other words, the thread is thicker than the reference thickness and is cut. When it is determined that a large load torque is applied, the output torque of the pulse motor can be increased by the drive control means.
Therefore, since the output torque of the pulse motor can be increased only when a large load torque is required, thread trimming defects can be suppressed without increasing the size of the pulse motor.

  The invention according to claim 2 is a sewing machine, wherein a thread trimming mechanism for cutting a thread passed through a needle below a needle plate, a pulse motor serving as a drive source for operating the thread trimming mechanism, and the pulse In driving the motor, pulse output means for inputting a command pulse to the pulse motor, command pulse detection means for detecting a command pulse input from the pulse output means to the pulse motor, and output pulses from the pulse motor The output pulse detection means to detect, the phase difference between the command pulse detected by the command pulse detection means and the pulse detected by the output pulse detection means is calculated, and this phase difference is calculated as the load torque applied to the pulse motor Load torque calculating means for determining whether or not the thread trimming mechanism is in contact with the needle. A contact determination threshold value storage means for storing a threshold value of a load torque applied to the motor, and a load torque calculated by the load torque calculation means is greater than a load torque threshold value stored in the contact determination threshold value storage means. Drive stop means for stopping the drive of the pulse motor.

According to the invention described in claim 2, the thread trimming operation is performed by operating the thread trimming mechanism by driving the pulse motor. At this time, the command pulse detecting means detects a command pulse input from the pulse output means to the pulse motor. The output pulse detection means detects the output pulse of the pulse motor driven by the command pulse.
When the command pulse and the output pulse are detected, the load torque calculating means calculates the phase difference between the command pulse detected by the command pulse detecting means and the pulse detected by the output pulse detecting means, and applies this phase difference to the pulse motor. Calculated as load torque.
The drive stop means stops the driving of the pulse motor when the load torque calculated by the load torque calculation means is larger than the load torque threshold stored in the contact determination threshold storage means.
As a result, the load torque calculated by the load torque calculating means is larger than the load torque threshold stored in the contact determination threshold storage means, in other words, the load trimming mechanism comes into contact with the needle and a large load torque is applied to the pulse motor. When it is determined that the pulse motor is applied, the drive of the pulse motor can be stopped by the drive stop means.
Therefore, in such a case, since the operation of the thread trimming mechanism can be stopped by stopping the driving of the pulse motor, the needle breakage can be prevented even if the thread is trimmed while the needle is lowered. Can do.

According to the first aspect of the present invention, the load torque calculated by the load torque calculating means is larger than the load torque threshold value stored in the thickness judgment threshold value storing means, in other words, the thickness that is based on the yarn. If it is thicker than this and it is determined that a large load torque is required for cutting, the output torque of the pulse motor can be increased by the drive control means.
Therefore, since the output torque of the pulse motor can be increased only when a large load torque is required, thread trimming defects can be suppressed without increasing the size of the pulse motor.

According to the second aspect of the present invention, the load torque calculated by the load torque calculating means is larger than the load torque threshold stored in the contact determination threshold storage means, in other words, the thread trimmer mechanism contacts the needle. If it is determined that a large load torque is applied to the pulse motor, the drive of the pulse motor can be stopped by the drive stop means.
Therefore, in such a case, since the operation of the thread trimming mechanism can be stopped by stopping the driving of the pulse motor, the needle breakage can be prevented even if the thread is trimmed while the needle is lowered. Can do.

Hereinafter, the best mode of a sewing machine according to the present invention will be described in detail with reference to the drawings.
<Configuration of sewing machine>
As shown in FIG. 1, the sewing machine 100 includes a thread trimming mechanism 1 that cuts a thread passed through the needle 6 below the needle plate 8, a pulse motor 2 that is a driving source for operating the thread trimming mechanism 1, and a pulse An encoder 3 as output pulse detecting means for detecting an output pulse from the motor 2 and a control device 4 for controlling the driving of the pulse motor 2 and controlling the driving of each part of the sewing machine 100 are provided.

(1) Thread trimming mechanism (a) Configuration of thread trimming mechanism The thread trimming mechanism 1 is connected to a pulse motor 2. The thread trimming mechanism 1 includes a thread trimming link 11 coupled to the pulse motor 2, a thread trimming coupling rod 13 coupled to the thread trimming link 11, and a fixed knife 14 provided on the thread trimming coupling rod 13 (see FIGS. 2 and 3). ), A movable knife 15 (see FIGS. 2 and 3), and the like.
The thread trimming link 11 is formed in a long bar shape in one direction slightly bent in the middle. One end of the thread trimming link 11 is connected to a cam 7, and this cam 7 is pivotally supported on the output shaft 2 a of the pulse motor 2. The thread trimming link 11 is rotatably attached to a sewing machine frame (not shown) by a support pin 12 at a bent portion 11b.
The other end portion 11c of the thread trimming link 11 is attached to the attachment plate 16 with a screw 17 so as to be rotatable together with one end portion of the thread trimming connecting rod 13.

The thread trimming connecting rod 13 is a rod-like member that is bent at a predetermined location so as to gradually move upward, and its distal end portion 13a (see FIG. 2) is held below the needle plate 8, that is, on the needle bar 5. It is provided so that it may be located under the needle 6 made.
As shown in FIG. 2, a movable knife connecting member 20 is rotatably connected to the distal end portion 13 a via a screw 21. Further, a thread trimming lever 23 is fixed on the movable knife connecting member 20. A connecting pin 22 fixed to the needle plate 8 is inserted into the movable knife connecting member 20 and the thread trimmer lever 23, and the movable knife connecting member 20 and the thread trimmer lever 23 can rotate around the connecting pin 22. It has become. One end 24a of the movable knife link 24 is rotatably connected to the tip of the thread trimming lever 23.

  A central portion of the movable knife 15 is connected to the other end 24b of the movable knife link 24 so as to be rotatable. An end 15 a of the movable knife 15 is attached to the set screw 25 so as to be rotatable. The set screw 25 is fixed to the needle plate 8. At the distal end of the movable knife 15, a thread wiper 15b that cuts the upper thread and the lower thread without cutting during the cutting operation, and a thread catcher that captures the thread paid by the thread wiper 15b and is curved inward. 15c and a movable blade 15d for further cutting the yarn are formed. A fixed knife 14 screwed to the needle plate 8 is provided in the vicinity of the movable knife 15, and an upper thread and a lower thread are held between the fixed knife 14 and the movable knife 15 and cut.

(B) Operation of the thread trimming mechanism Next, the operation of the thread trimming mechanism 1 will be described. When the thread trimming mechanism 1 has finished sewing, the output shaft 2a of the pulse motor 2 is rotated about its axis by driving the pulse motor 2 before lifting. When the output shaft 2a rotates, the cam 7 provided on the output shaft 2a also rotates together with the output shaft 2a. When the cam 7 rotates, the thread trimming link 11 connected to the cam 7 rotates counterclockwise about the support pin 12 toward the plane of FIG. 1, and its lower end moves forward (female side). To do. As a result, the thread trimming connecting rod 13 moves forward and the movable knife connecting member 20 is pushed via the screw 21, so that the movable knife connecting member 20 and the thread trimming lever 23 rotate around the connecting screw 22. .
As shown in FIG. 3A, the movable knife link 24 connected to the tip of the thread trimmer lever 23 is pushed backward by the operation of the thread trimming lever 23, and the movable knife 15 rotates clockwise around the set screw 25. By this rotation operation, the upper thread and the lower thread are separated by the thread wiper 15b, and only the upper thread and the lower thread to be cut are positioned between the thread catcher 15c and the fixed blade 14a.

  On the other hand, when the thread trimming link 11 rotates clockwise around the support pin 12 toward the paper surface of FIG. 1 and its lower end returns to the rear, each member constituting the thread trimming mechanism 1 performs the reverse operation. To do. In other words, the movable knife 15 rotates so as to return from the state shown in FIG. 3B, and at this time, the movable knife 15 rotates while catching the upper thread and the lower thread by the thread catching portion 15c. As shown in FIG. 3 (c), the upper thread and the lower thread approach each other, the movable blade 15d and the fixed blade 14a are matched, and the thread is cut. The movable knife member 15 continues to reverse and returns to the state shown in FIG.

(2) Pulse Motor As shown in FIG. 1, the pulse motor 2 is driven and controlled by the control device 4. The operation of the thread trimming mechanism 1 is performed by controlling the operation of the cam 7 while counting the rotation direction of the pulse motor 2 and the number of pulses in operation by the control device 4.
The torque output from the pulse motor 2 is performed by known PWM control, and the torque output from the pulse motor 2 can be increased by increasing the width of the command pulse. That is, the output torque can be adjusted by changing the pulse width of the command pulse.

(3) Encoder As shown in FIG. 1, the encoder 3 is provided on the output shaft 2 a of the pulse motor 2 and detects a pulse of the drive output of the output shaft 2 a of the pulse motor 2.

(4) Control Device (a) Configuration of Control Device As shown in FIG. 4, the control device 4 includes a pulse output unit 41 that inputs a command pulse to the pulse motor 2 when the pulse motor 2 is driven. That is, the pulse output unit 41 functions as a pulse output unit.
The control device 4 includes a command pulse detection unit 42 that detects a command pulse input from the pulse output unit 41 to the pulse motor 2. That is, the command pulse detector 42 functions as a command pulse detector.
The control device 4 calculates the phase difference between the command pulse detected by the command pulse detection unit 42 and the pulse detected by the encoder 3, and calculates the phase difference as a load torque applied to the pulse motor 2. It has. That is, the load torque calculation unit 43 functions as load torque calculation means.

The control device 4 includes a storage unit that stores threshold data 44a of load torque applied to the pulse motor 2 at the determination boundary when determining whether the thread passed through the needle 6 is thicker than a reference thickness. ing. That is, the storage unit 44 functions as a thickness determination threshold storage unit.
The storage unit 44 also stores threshold value data of load torque applied to the pulse motor 2 at the boundary of determination when determining whether the fixed knife 14 or the movable knife 15 of the thread trimming mechanism 1 is in contact with the needle 6. 44b is stored. That is, the storage unit 44 also functions as a contact determination threshold value storage unit.
Here, the load torque threshold data 44a and 44b may be values that have been experimentally measured in advance through experiments or the like, but the threshold data 44a is used when determining the thickness of the yarn. Since 44b is used when determining whether the thread trimming mechanism 1 is in contact with the needle 6, the threshold value of the load torque is set larger in the threshold data 44b to which a larger load torque is applied. The load torque value based on the load torque threshold data 44a is T1, and the load torque value based on the load torque threshold data 44b is T2.

When the load torque calculated by the load torque calculation unit 43 is larger than the load torque value T1 stored in the storage unit 44, the control device 4 reduces the drive speed of the pulse motor 2 and increases the output torque. A control unit 45 is provided. That is, the drive control unit 45 functions as a drive control unit.
The control device 4 includes a drive stopping unit 46 that stops the driving of the pulse motor 2 when the load torque calculated by the load torque calculating unit 43 is larger than the load torque value T2 stored in the storage unit 44. . That is, the drive stop unit 46 functions as drive stop means.
Each part is processed by a known CPU executing a program for realizing processing having the function of each part. Further, not only software such as a program but also hardware such as a circuit may be used.

(B) Processing of control device when performing thread trimming Next, processing of the control device 4 when performing thread trimming will be described.
As shown in FIG. 5, when performing thread trimming, the pulse output unit 41 of the control device 4 transmits a command pulse for driving the pulse motor 2 to the pulse motor 2 (step S1). Note that when the pulse motor 2 is driven, the pulse motor 2 is driven at a high speed and a relatively small output torque in consideration of reducing the load on the pulse motor 2 and improving work efficiency.
Next, the load torque calculation unit 43 of the control device 4 includes a command pulse transmitted from the pulse output unit 41 detected by the command pulse detection unit 42 of the control device 4 to the pulse motor 2 and a pulse motor detected by the encoder 3. 2 is calculated as a load torque applied to the pulse motor 2 (step S2).

  The control device 4 determines that the calculated load torque is larger than the load torque value T1 based on the load torque threshold data 44a stored in the storage unit 44 (the calculated load torque is the same as the load torque value T1). Whether or not the value is included (step S3). If the drive control unit 45 of the control device 4 determines that the calculated load torque is greater than the load torque value T1 (step S3: YES), the pulse output unit 41 transmits the pulse torque to the pulse motor 2. The command pulse is changed to reduce the drive speed of the pulse motor 2 and increase the output torque from the pulse motor 2 (step S4).

On the other hand, if the drive control unit 45 determines that the calculated load torque is smaller than the load torque value T1 (step S3: NO), the control device 4 determines whether or not the thread trimming is finished. However, when the control device 4 determines that the thread trimming has been completed (step S5: YES), the control device 4 terminates this processing, and the control device 4 determines that the thread trimming has not been completed. In the case (step S5: NO), the process returns to step S2.
In step S4, after the drive control unit 45 decelerates the drive speed of the pulse motor 2 and increases the output torque, the load torque calculation unit 43 calculates the pulse motor from the pulse output unit 41 detected by the command pulse detection unit 42. 2 is calculated as a load torque applied to the pulse motor 2, and the phase difference between the command pulse transmitted to the output motor 2 and the output pulse output from the pulse motor 2 to the output shaft 2a is calculated. (Step S6).

  Then, the control device 4 determines that the calculated load torque is larger than the load torque value T2 based on the load torque threshold data 44b stored in the storage unit 44 (the calculated load torque is the same as the load torque value T2). Whether or not the value is included (step S7). Here, if the drive stop unit 46 determines that the calculated load torque is larger than the load torque value T2 (step S7: YES), the command output unit 41 transmits a command pulse to the pulse motor 2. Is interrupted to stop the driving of the pulse motor 2 (step S8), and an error is displayed on an operation panel or the like provided in the sewing machine 100 (step S9).

On the other hand, if the control device 4 determines that the calculated load torque is smaller than the load torque value T2 (step S7: NO), the drive control unit 45 transmits the pulse output unit 41 to the pulse motor 2. The command pulse is changed to reduce the drive speed of the pulse motor 2 and increase the output torque from the pulse motor 2 (step S10).
Next, the control device 4 determines whether or not the thread trimming has been completed (step S11). When the control device 4 determines that the thread trimming has been completed (step S11: YES), the present processing is terminated. When the control device 4 determines that the thread trimming has not ended (step S11: NO), the control device 4 returns to step S6.

<Effects of Embodiment>
Thus, according to the sewing machine 100, the thread trimming operation is performed by operating the thread trimming mechanism 1 by driving the pulse motor 2. At this time, the command pulse detector 42 detects a command pulse input from the pulse output unit 41 to the pulse motor 2. The encoder 3 detects the output pulse of the pulse motor 2 driven by the command pulse.
When the command pulse and the output pulse are detected, the load torque calculation unit 43 calculates the phase difference between the command pulse detected by the command pulse detection unit 42 and the pulse detected by the encoder 3, and applies this phase difference to the pulse motor. Calculated as load torque.
When the load torque calculated by the load torque calculation unit 43 is larger than the load torque threshold data 44a stored in the storage unit 44a, the drive control unit 45 decelerates the drive speed of the pulse motor 2 and outputs it. Increase torque.
Accordingly, the load torque calculated by the load torque calculation unit 43 is larger than the load torque threshold data 44a stored in the storage unit 44. In other words, the yarn is thicker than the reference thickness and is large for cutting. When it is determined that the load torque is applied, the output torque of the pulse motor 2 can be increased by the drive control unit 45.
Therefore, since the output torque of the pulse motor 2 can be increased only when a large load torque is required, the thread trimming defect can be suppressed without increasing the size of the pulse motor 2.

Further, the drive stop unit 46 stops the driving of the pulse motor 2 when the load torque calculated by the load torque calculation unit 43 is larger than the load torque threshold data 44 b stored in the storage unit 44.
Thereby, the load torque calculated by the load torque calculation unit 43 is larger than the load torque threshold value data 44b stored in the storage unit 44, in other words, the thread trimming mechanism 1 contacts the needle 6 to the pulse motor 2. When it is determined that a large load torque is applied, the drive stop unit 46 can stop the driving of the pulse motor 2.
Therefore, in such a case, the operation of the thread trimming mechanism 1 can be stopped by stopping the driving of the pulse motor 2, so that even if the thread trimming is performed with the needle 6 lowered, the needle breaks. Can be prevented.

(Other)
The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the control device 4 includes the drive control unit 45 and the drive stop unit 46. However, the control device 4 may include either one.
Further, since the drive control unit 45 has determined only one threshold value, it has only been determined whether the thread is thick or thin. However, by setting a plurality of threshold values, the drive control of the pulse motor 2 can be controlled based on the thread thickness. It may be further subdivided accordingly.

FIG. 2 is a schematic perspective view around a thread trimming mechanism in a sewing machine. The perspective view around the fixed knife and movable knife in the thread trimming mechanism. The top view which shows the operation | movement at the time of thread trimming of the fixed knife and movable knife in a thread trimming mechanism. The block diagram which shows the structure of a sewing machine. The flowchart which shows the thread trimming process of a control apparatus.

Explanation of symbols

1 Thread trimming mechanism 2 Pulse motor 3 Encoder (output pulse detection means)
4 Control device 6 Needle 8 Needle plate 41 Pulse output unit (pulse output means)
42 Command pulse detector (command pulse detection means)
43 Load torque calculation unit (load torque calculation means)
44 storage unit (thickness determination threshold storage means, contact determination threshold storage means)
45 Drive control unit (drive control means)
46 Drive stop section (drive stop means)

Claims (2)

A thread trimming mechanism for cutting the thread passed through the needle below the needle plate;
A pulse motor serving as a drive source for operating the thread trimming mechanism;
In driving the pulse motor, pulse output means for inputting a command pulse to the pulse motor;
Command pulse detection means for detecting a command pulse input to the pulse motor from the pulse output means;
Output pulse detection means for detecting an output pulse from the pulse motor;
A load torque calculating means for calculating a phase difference between the command pulse detected by the command pulse detecting means and a pulse detected by the output pulse detecting means, and calculating the phase difference as a load torque applied to the pulse motor;
A thickness determination threshold value storage means for storing a threshold value of a load torque applied to the pulse motor at a boundary of the determination when determining whether the thread passed through the needle is thicker than a reference thickness;
Drive that reduces the drive speed of the pulse motor and increases the output torque when the load torque calculated by the load torque calculation means is larger than the load torque threshold stored in the thickness judgment threshold storage means Control means;
A sewing machine comprising: A thread trimming mechanism for cutting the thread passed through the needle below the needle plate;
A pulse motor serving as a drive source for operating the thread trimming mechanism;
In driving the pulse motor, pulse output means for inputting a command pulse to the pulse motor;
Command pulse detection means for detecting a command pulse input to the pulse motor from the pulse output means;
Output pulse detection means for detecting an output pulse from the pulse motor;
A load torque calculating means for calculating a phase difference between the command pulse detected by the command pulse detecting means and a pulse detected by the output pulse detecting means, and calculating the phase difference as a load torque applied to the pulse motor;
A contact determination threshold value storage means for storing a threshold value of a load torque applied to the pulse motor at the determination boundary when determining whether or not the thread trimming mechanism is in contact with the needle;
A drive stopping means for stopping the driving of the pulse motor when the load torque calculated by the load torque calculating means is greater than a load torque threshold stored in the contact determination threshold storage means;
A sewing machine comprising:

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