KR20060080873A - Sewing machine - Google Patents

Abstract

After cutting the thread, make the length of the thread coming out from the needle hole of the sewing needle appropriate.

The sewing machine (M) has a thread (T) inserted into the needle hole formed at the tip, and the sewing needle (1) for sewing the sewing object placed on the needle plate by Shanghaidong, and the thread (T) after finishing a predetermined amount of sewing. ), A wiper (2) for removing the thread (T) from the object to be sewn across the sewing needle (1) and the object after the thread (T) is cut by the thread cutting device, and the needle hole When the thread T is removed from the object to be sealed by the thread tensioning means 3 for applying tension to the thread T inserted through the wiper 2, the tension is applied to the thread, and the thread ( When T) is taken out, mounting force control means for controlling the operation of the mounting force applying means 3 to release the tension applied to the yarn T is provided.

Description

Sewing machine {SEWING MACHINE}

1 is a perspective view of a sewing machine.

2 is a perspective view of the vicinity of the center presser foot.

3 is a side view showing the positional relationship between the wiper, the sewing needle, and the center presser foot when the thread is pulled out by the wiper.

4 is a side view of the wiper device.

5 is a front view of the wiper device.

6 is an enlarged view of the actual rejection.

7 is a perspective view of the second mounting force adjusting device.

8 is a front view of the second mounting force adjusting device.

9 is an exploded perspective view of the second mounting force adjusting device.

10 is a sectional view of the solenoid.

11 is a block diagram of a control device.

It is a flowchart which shows control by the control apparatus at the time of operation | movement from cutting | disconnection of a thread to thread extraction.

Fig. 13 is a flowchart showing control by the control device at the time of abnormality occurrence.

Explanation of symbols on the main parts of the drawings

1: sewing needle 2: wiper device

3: mounting force adjusting device (mounting force applying means)

5: control device (mounting force control means, sewing needle control means)

7: Solenoid 25 for mounting force adjustment: Wiper

31: first mounting force adjusting device 32: second mounting force adjusting device

33: thread holder spring 34: sensor

M: Sewing Machine T: Thread

The present invention relates to a sewing machine.

Conventionally, the sewing machine is provided with a thread tension adjusting device for imparting tension to the thread, and by this thread tension adjusting device, appropriate tension can be imparted to the needle stitches. The mounting force adjusting device is arranged so that two mounting force adjusting trays face each other, and the mounting force adjusting tray is pushed by pushing one mounting force adjusting tray onto the other mounting force adjusting tray by the pressing force of the mounting force adjusting spring. Tension can be imparted to the thread fitted in the.

The sewing machine is provided with two such mounting force adjusting devices. The first thread tension adjusting device provided near the thread supply source always gives tension to the thread regardless of the sewing situation of the sewing machine, and the second thread tension adjusting device installed near the sewing needle is applied to the thread only during sewing. 1 It gives a much larger tension than the thread tension adjusting device, and releases the tension to a thread at the time of cutting of a thread after finishing sewing (for example, refer patent document 1).

In this way, while the tension is applied to the thread by the first thread tension adjusting device, the tension is applied to the thread by releasing the tension by the second thread tension adjusting device, and the thread is released from the needle hole of the sewing needle after thread cutting. The length of the thread can be adjusted. Here, when the tension applied to the thread from the first thread tension adjusting device is made small, the amount of thread drawn out from the thread supply source by the thread cutting blade at the time of thread cutting increases, and the length of the thread coming out from the needle hole after thread cutting is increased. Lengthens. On the contrary, when the tension applied to the thread from the first thread tension adjusting device is increased, the amount of thread pulled out from the thread supply source by the thread cutting blade at the time of thread cutting decreases, and the length of the thread exiting the needle hole after thread cutting is reduced. Becomes shorter. The length of the thread coming out from the needle hole is an important factor that determines the quality of the next sewing.If the length of the thread coming out from the needle hole is too long, extra thread remains at the beginning of sewing, which is not good in appearance.結節) is not made, needle stitch skipping occurs.

In addition, after the thread is cut, the wiper is removed from the object to be sealed. The wiper moves across the sewing needle and the object to be stitched and is threaded to remove it from the object to be stitched. Therefore, when the thread is removed from the object to be sealed by the wiper, the tension is applied to the thread only by the first thread tension adjusting device.

[Patent Document 1] Japanese Patent Laid-Open No. 2002-52286

However, if the sewing object is made of synthetic leather or the like at a high speed, the sewing needle becomes hot due to friction with the sewing object, and the hole punctured by the sewing needle may melt and harden together with the thread.

For this reason, if the tension of the first thread tension adjusting device is small when the thread is removed from the sewing object by the wiper, there is a problem that the thread is released from the thread supply source, and the length of the thread coming out of the needle hole after thread cutting becomes long. . On the contrary, when the tension of the first thread tension adjusting device is excessively increased, the amount of thread drawn out from the thread supply source by the thread cutting blade at the time of thread cutting decreases, and the length of the thread coming out from the needle hole after thread cutting is shortened. Had a problem. Therefore, it was difficult to adjust the tension of the first mounting force adjusting device.

The present invention has been made to solve the above problems, and an object thereof is to provide a sewing machine that can make the length of the thread coming out of the needle hole of the sewing needle to an appropriate length after cutting the thread.

In order to solve the above problems, the invention described in claim 1 includes a needle for passing a thread through a needle hole formed at the tip, and sewing a sewing object placed on a needle plate by shanghai copper, and a thread after finishing a predetermined amount of sewing. A thread cutting device for cutting a thread, a wiper for pulling a thread from the sewing object across the sewing needle and the sewing object after the thread is cut by the thread cutting device, and tensioning the thread inserted into the needle hole. A sewing machine having a mounting force imparting means for imparting, wherein said wiper gives tension to a thread when removing said thread from said sewing object and releases the tension applied to the thread when the thread is removed from said sewing object. And mounting force control means for controlling the operation of the force applying means.

According to the invention as set forth in claim 1, the mounting force adjusting control means imparts the tension to the thread when the thread is removed from the object to be sewn by the wiper and releases the tension applied to the thread when the thread is removed from the object to be sewn. Control the operation of the means. As a result, since the tension is applied to the thread only when the thread is taken out, the thread is not drawn out from the thread supply source by the wiper, and the length of the thread coming out of the needle hole of the sewing needle after cutting the thread can be made the optimum length. . Thereby, the external appearance of the to-be-sealed | blocked object does not worsen and it can also prevent that needle stitch skips at the time of sewing. In addition, since the tension applied to the thread is released after removing the thread from the object to be sewing, it is possible to easily change the thread at the time of stopping the sewing machine or to sew the thread.

In the sewing machine according to claim 1, in the sewing machine according to claim 1, a thread catching spring is provided on a path of a thread from a thread supply source to a needle hole, and hangs the thread and is elastically deformed by the tension of the thread, and the thread And a sensor for detecting the presence of the thread catching spring at an initial position before the tension of the thread acts on the catching spring, and after the wiper crosses between the sewing needle and the sewing object, the sensor catches the thread catching spring. When not detected, characterized in that it comprises a sewing needle control means for stopping the vertical operation of the sewing needle.

According to the invention of claim 2, the sewing needle control means stops the up and down operation of the sewing needle when the sensor does not detect the thread spring after the wiper crosses between the sewing needle and the sewing object. Thereby, it can be detected whether the wiper returned to the original position. In other words, the thread spring does not return to the initial position because the thread is tensioned, and the tension is applied because the wiper is trying to pull the thread out of the sewing object, so the thread spring is returned to the initial position. If not, the wiper will not return to its original position. Thereby, the needle can be prevented from being broken by contact with the center presser foot or by contact with the sewing needle due to the wiper not returning to the original position.

In addition, since the state of the wiper can also be determined by the detection of the thread catching spring, a dedicated sensor for detecting whether the wiper is returned to its original position is unnecessary.

EMBODIMENT OF THE INVENTION Hereinafter, the most preferable form of the sewing machine which concerns on this invention is described in detail, referring drawings.

<Configuration of sewing machine>

1 to 11, the sewing machine M is connected to a sewing machine motor 10 (see FIG. 11), which is a driving source, through a link mechanism, and moves up and down by driving the sewing machine motor 10. Sewing needle 1 provided in 1b), a thread cutting device 8 (see FIG. 11) for cutting a thread after finishing sewing of a predetermined cycle, and a sewing needle 1 after the thread is cut by the thread cutting device 8; And a wiper device 2 for pulling the thread from the object to be sewn across between the object to be placed on the needle plate and the thread inserted into the needle hole 1a of the sewing needle 1 (see FIG. 3). Sealed by the tension adjusting device 3 as the mounting force imparting means, the central presser foot device 4 for pressing the sewing object toward the needle plate when the sewing needle 1 is removed from the sewing object, and the wiper device 2. When pulling the thread out of the offering, the tension is applied to the thread, and the thread Afterwards, while controlling the operation of the mounting force adjusting device 3 to release the tension applied to the thread, the wiper device 2 crosses between the sewing needle 1 and the sewing object, and then the sensor 34 (Fig. 7). Control device 5 (see FIG. 11) to stop the operation of the needle bar 1b when the thread holding spring 33 (see FIGS. 7 and 8) installed in the mounting force adjusting device 3 has not detected. Equipped with.

(Sewing needle)

The sewing needle 1 is driven in the up and down direction of the sewing machine M in conjunction with the drive of the needle bar 1b, and sewing the sewing object placed on the needle plate by shanghaidong. At the tip of the sewing needle 1, a needle hole 1a for inserting the thread is formed.

(Wiper device)

As shown in FIGS. 4 to 6, the wiper device 2 includes a wiper solenoid 20 (see FIG. 11) installed inside the sewing machine frame, and a plurality of connection links 21 connected to the wiper solenoid 20. And a swing member 22 connected to the front end of the link link 21, a cam member 23 connected to the swing link 22, a shaft member 24 for rotating the cam member 23, and a shaft member. The wiper 25 connected to the base end at 24 is provided.

That is, when the drive of the wiper solenoid 20 is transmitted to the swing link 22 through the link link 21, the swing link 22 swings up and down, and swings up and down the swing link 22. The cam member 23 is converted into rotational motion to rotate the shaft member 24. By the rotation of the shaft member 24, as shown in FIG. 5, the front end rotates with the base end as the rotation center. As shown in FIG. 6, the tip of the wiper 25 is formed with an actual reject 25a formed in the shape of a hook. The actual reject 25a is formed between the center presser foot 41 and the sewing needle 1 when not in use. When the swinging link 22 swings and uses the wiper 25, the tip end of the thread T crosses between the center presser foot 41 and the sewing needle 1, as shown in FIG. It is meant to be shouted. The tip T of the wiper 25 crosses between the center presser foot 41 and the sewing needle 1 so that the actual reject 25a formed in the shape of a hook is inserted into the to-be-sealed material and the center presser foot 41. It is to be able to take out.

(Tension control device)

The mounting force adjusting device 3 (mounting force applying means) includes a first mounting force adjusting device 31 provided near the thread supply source of the sewing machine M, and a first, as shown in Figs. A second mounting force adjusting device 32 is provided closer to the sewing needle 1 than the mounting force adjusting device 31.

The first thread tension adjusting device 31 is provided above the distal end of the sewing machine arm and always gives tension to the thread T, and at the time of cutting the thread T by the thread cutting device 8. It has a function of preventing the thread from being excessively released from the thread supply.

The second thread tension adjusting device 32 is provided below the first thread tension adjusting device 31, and has a function of preventing the needle stitches from loosening by applying an appropriate tension to the thread T at the time of sewing. . Here, the tension applied to the thread T by the second mounting tension adjusting device 32 is greater than the tension applied to the thread T by the first mounting tension adjusting device 31.

Here, as shown in Figs. 7 to 10, the second mounting force adjusting device 32 is configured to apply tension to the yarn T by the suction force of the mounting force adjusting solenoid 7.

The second mounting force adjusting device 32 allows the fixing screws 68 and 69 to pass through the screw holes 63a and 63a of the base member 63 and mounts the front ends of the fixing screws 68 and 69. The base member 63 and the mounting force adjusting solenoid 7 are integrally fixed by turning into the screw holes 70a and 70a of the force adjusting solenoid 7.

The thread tension adjusting shaft 61 has a threaded portion 61a of a tension adjusting tray 62, a base member 63, a mounting tension adjusting shaft nut 64, a washer 65, and a tension adjusting spring 66. And the screw was inserted into the screw hole 71a of the plunger 71 (movable part) of the mounting force adjusting solenoid 7 in the state where the washer 67 was inserted. The fixing position of the mounting force adjustment shaft 61 and the plunger 71 can be adjusted suitably according to the tightening of the mounting force adjustment shaft nut 64. In the case where the tension of the tension adjusting spring 66 lowers the tension of the thread in a state in which a predetermined tension is applied to the thread, the thrust of the mounting force adjustment shaft 61 is reduced even though the thrust caused by the mounting force adjusting solenoid 7 is lowered. It is provided in order to prevent the situation where the mounting force adjustment shaft 61 does not return by the frictional force caught around. Thereby, the tension adjustment spring 66 presses in the direction which expands between the washers 65 and 67, ie, the direction in which the mounting force adjustment shaft 61 is separated from the mounting force adjustment solenoid 7.

The mounting force adjusting solenoid 7 is provided with the plunger 71, the frame 72, the coil frame 73, the coil 74, the magnetic member 75, etc. as shown in FIG. The plunger 71 is supported by the bearings 72a and 72b so as not to rotate while being movable in the axial direction. The magnetic member 75 fixed to the plunger 71 is cylindrical in shape, and a portion thereof is formed with an end portion 75a for changing the diameter from the shaft center. By this shape, a specific stroke section in which the thrust of the plunger 71 does not follow the stroke can be obtained.

Further, as the energizing current output to the mounting force adjusting solenoid 7 increases, the thrust increases. The mounting force adjusting solenoid 7 is attached to the direction in which the mounting force regulating shaft 61 is drawn in (the tension is applied to the thread) by energizing the coil 74, and the mounting force regulating shaft ( The mounting force imparted by 61 becomes large. That is, in the second mounting force adjusting device 32, the mounting force is changed only by changing the energizing current, and the current value is controlled in accordance with the instruction signal of the control device 5.

7, 8, in addition to the first mounting force adjusting device 31 and the second mounting force adjusting device 32, the second mounting force adjusting device 32 is relatively to the yarn T. As shown in FIG. The thread catching spring 33 which provides a small tension and finely adjusts the tension of the thread T is provided. When the thread T on the sewing needle 1 side, which is tensioned by the second thread tension adjusting device 32, passes through the thread catching spring 33, and the tension acting on the thread T increases, As shown in FIG. 8, the thread catching spring 33 is bent toward the sewing needle 1 side. That is, the thread catching spring 33 is bent when the tension | pulling acting on the thread T is increased by the thread extraction operation | work from the to-be-sealed object by the wiper apparatus 2, and when the thread T is cut | disconnected, the thread catching spring Reference numeral 33 returns to the initial position before the operation by the restoring force.

In the vicinity of the thread catching spring 33, the sensor 34 which detects whether the thread catching spring 33 is in an initial position is provided. For example, the sensor 34 is in contact with the thread catching spring 33 when the thread catching spring 33 is in an initial position, and is separated from the sensor 34 when the thread catching spring 33 is elastically deformed. It is configured to detect the presence of the thread catching spring 33 in accordance with the contact.

(Center presser foot device)

As shown in FIGS. 1-3, the center presser foot apparatus 4 is provided in the upper shaft which drives the needle bar 1b provided with the sewing needle 1 in the up-down direction, as shown in FIG. The upper shaft is connected to the sewing machine motor 10, the driving force of the sewing machine motor 10 is transmitted to the center presser foot 41 through a link mechanism, it is possible to perform the shangdong movement of the center presser foot 41. have. The center presser foot 41 is moved up and down in synchronization with the needle bar 1b, and when the sewing needle 1 is lifted up and pulled out from the object to be pressed, the center presser foot can be pressed to prevent the object to be fluttered. It is supposed to be.

In addition, the center presser foot 41 is connected to the center presser foot height adjusting stepping motor 40 (see FIG. 11), which is installed separately from the sewing machine motor 10, through a link mechanism, and the to-be-dead-dead of the center presser foot 41. It is possible to adjust the height from the upper surface of the needle plate when pressing.

(Control device)

As shown in FIG. 11, the control apparatus 5 is equipped with the CPU 51 which performs various processes, and the memory 52 in which the program and data were stored.

In the memory 52, a work area 53 in which the CPU 51 performs processing, a data area 54 for recording data to be used for processing, and a program area 55 in which programs for performing various processes are stored. ) Is formed.

In the data area 54, sewing data 54a relating to sewing on the object to be sewing is stored. The sewing data 54a includes the coordinates of the needle drop position, the height of the center presser foot from the needle plate, the lifting timing of the needle bar 1b, the timing of driving the second mounting force adjusting device 32, and the second mounting force adjusting device ( The tension value imparted to the yarn by 32) is stored.

In the program area 55, on the basis of the sewing data 54a stored in the data area 54, when the wiper device 2 pulls out the thread from the object to be sealed, tension is applied to the thread, and the thread is removed from the object to be sealed. When pulled out, the mounting force control program 55a which controls the operation | movement of the 2nd mounting force adjustment device 32 is memorize | stored so that the tension | tensile_strength given to the thread may be released. Therefore, by the CPU 51 executing the mounting force control program 55a, tension provision to the thread by the second mounting force adjusting device 32 is controlled, so that the control device 5 functions as mounting force control means. do.

Further, in the program area 55, the wiper device 2 crosses between the sewing needle 1 and the object to be sewing, based on the sewing data 54a stored in the data area 54, and then the sensor 34 The sewing needle control program 55b for stopping the operation of the sewing needle 1 when the thread catching spring 33 is not detected is stored. Therefore, by the CPU 51 executing the sewing needle control program 55b, the driving of the needle bar 1b is controlled, and the control device 5 functions as the sewing needle control means.

<Operation from thread cutting to thread removal>

Next, in sewing by the sewing machine which has the said structure, the operation | movement from thread cutting to thread extraction is demonstrated.

As shown in FIG. 12, the control apparatus 5 determines whether it is time to cut | disconnect a thread in the middle of sewing (step S1). Here, when it is determined that the control device 5 is time to cut the thread (step S1: YES), the control device 5 executes the mounting force adjustment control program 55a, whereby the control device 5 performs the second mounting. The tension is imparted to the thread by the force adjusting device 32 (step S2). On the other hand, when the control device 5 determines that it is not the time to cut the thread (step S1: NO), the control device 5 repeats the determination.

Next, the control apparatus 5 transmits an operation signal to the thread cutting device 8, and cuts a thread by the thread cutting device 8 (step S3).

Then, the control apparatus 5 determines whether it is time to pull out a thread from the to-be-sealed material and the center presser foot 41 (step S4). Here, when the control device 5 detects that the sewing needle 1 is in a predetermined position by the spindle sensor 9 (see FIG. 11) and determines that it is time to remove the thread (step S4: YES), the control device 5 By executing the mounting force adjustment control program 55a, the control device 5 causes the tension to the thread again by the second mounting force adjustment device 32 (step S5). On the other hand, when it is determined that the control device 5 is not the time to pull out the yarn (step S4: NO), the control device 5 repeats the above determination.

After the tension is again applied to the thread by the second mounting force adjusting device 32, the control device 5 transmits an operation signal to the wiper device 2 so that the thread is pulled out of the object to be sealed and the presser foot 41. (Step S6).

Next, the control apparatus 5 determines whether thread extraction is complete | finished from the to-be-sealed material and the center presser foot 41 (step S7). Here, when the control apparatus 5 judges that thread extraction is complete | finished (step S7: YES), the control apparatus 5 executes the mounting force adjustment control program 55a, and the control apparatus 5 performs a 2nd mounting force. The tension on the thread by the adjusting device 32 is released (step S8), thereby ending the present process. On the other hand, when the control apparatus 5 determines that thread extraction is not complete (step S7: NO), the control apparatus 5 repeats the said determination.

<Sewing Machine Operation in Case of Abnormality>

Next, the operation when an abnormality occurs in the sewing machine will be described.

As shown in FIG. 13, the control apparatus 5 judges whether the sensor 34 detected that the thread catching spring 33 is in an initial position (step S21). Here, when the control device 5 determines that the sensor 34 has detected that the thread catching spring 33 is in the initial position (step S21: YES), the control device 5 executes a predetermined sewing program by executing a predetermined sewing program. Then, sewing is started (step S22). On the other hand, when the control device 5 determines that the sensor 34 has not detected that the thread catching spring 23 is in the initial position (step S21: NO), the control device 5 repeats the determination.

Even during sewing, the control device 5 continues to detect the position of the thread catching spring 33 by the sensor 34, so that the sensor 34 detects that the thread catching spring 33 is in the initial position. If it is determined that the detection is continued for a predetermined time or more (step S23: YES), the control device 5 stops all the driving sources related to the drive of the sewing machine (step S25), thereby terminating the present process. On the other hand, when the control device 5 determines that the sensor 34 has not continuously detected that the thread catching spring 33 is in the initial position for a predetermined time or more (step S23: NO), the control device 5 is a wiper. It is determined whether the sensor 34 has detected that the thread catching spring 33 is in the initial position within a predetermined time after the device 2 is driven (step S24).

In step S24, when the control device 5 determines that the sensor 34 detects that the thread catching spring 23 is in the initial position within a predetermined time after the drive of the wiper device 2 (step S24: YES), control The apparatus 5 accesses the sewing data 54a to determine whether sewing is finished (step S26). On the other hand, when the control device 5 determines that the sensor 34 has not detected that the thread catching spring 33 is in the initial position within a predetermined time after driving the wiper device 2 (step S24: NO), the control device (5) stops all the drive sources related to the drive of the sewing machine (step S25), thereby terminating the present process.

In step S26, when the control device 5 determines that sewing is finished (step S26: YES), the processing is terminated by this, and when the control device 5 determines that sewing is not finished (step S26: NO), The control apparatus 5 returns to the judgment of step S23, and repeats the above judgment.

<Effects of Embodiments>

According to the sewing machine M in the embodiment, the control device 5 applies tension to the thread T when the thread T is pulled out of the object to be sewing by the wiper 25, and the thread T from the object to be sewing. When it is taken out, the operation of the second mounting force adjusting device 32 is controlled to release the tension applied to the thread T. Accordingly, since the tension is applied to the thread T only when the thread T is pulled out, the thread T is not drawn out from the thread supply source by the wiper 25, and the sewing needle after cutting the thread T is cut off. The length of the thread T coming out of the needle hole of (1) can be made into the optimal length. Thereby, the external appearance of the to-be-sealed | blocked object does not worsen and it can prevent that needle stitch skips at the time of sewing. In addition, after the thread T is removed from the object to be sealed, the tension applied to the thread T is released, so that the thread changing and the sewing can be easily performed when the sewing machine is stopped.

In addition, since the second mounting force adjusting device 32 imparts tension to the thread T by the suction force of the mounting force adjusting solenoid 7, the tension applied to the thread T can be electrically controlled. The tension applied to the thread T can be set precisely and accurately in multiple steps.

In addition, a mounting force adjusting device may be used in which a seal T is inserted between two trays, and the tray is always press-contacted with an elastic member such as a spring to float the tray with the mounting force adjusting solenoid 7. have.

Alternatively, the mounting force may be changed by rotating the pinion by using a stepping motor instead of the mounting force adjusting solenoid 7 and moving the rack back and forth.

In addition, the control apparatus 5 is a sewing needle 1 when the sensor 34 does not detect the thread catching spring 33, after the wiper 25 has crossed between the sewing needle 1 and the to-be-processed object. ) Is stopped. Thereby, whether the wiper 25 returned to the original position can be detected. That is, when the thread catching spring 33 is not returned to the initial position, the tension is applied to the thread T, and the tension is applied to the wiper 25 to hang the thread T to remove it from the object to be sewing. Therefore, if the thread catching spring 33 does not return to the initial position, the wiper 25 also does not return to the original position. Thereby, the needle can be prevented from being broken by the contact with the center presser foot 41 or the contact with the sewing needle 1 as the wiper 25 does not return to its original position.

In addition, since the state of the wiper 25 can also be determined by the detection of the thread catching spring 33, a dedicated sensor for detecting whether the wiper 25 has returned to its original position is unnecessary.

In addition, this invention is not limited to the said embodiment. For example, as a detection method of a thread catching spring, the structure which detects the light emitted from the light source by providing a reflecting plate in the thread catching spring, for example may be sufficient as it. Further, in the process of detecting an abnormality in the sewing machine, a method of determining whether the sensor continuously detects that the thread catching spring is in the initial position for a predetermined time or more, and the thread catching spring is initialized within a predetermined time after driving of the wiper device. The method of judging by the sensor whether or not the position is present may be individually processed, or may be used in combination as described above. In addition, the structure of the mounting force adjusting device can be freely changed.

According to the invention of claim 1, since the tension is applied to the thread only when the thread is pulled out, the thread is not drawn out from the thread supply by the wiper, so that the length of the thread coming out from the needle hole of the sewing needle after cutting the thread is optimal. Can be the length of. Thereby, the external appearance of the to-be-sealed | blocked object does not worsen and it can also prevent that needle stitch skips at the time of sewing. In addition, since the tension applied to the thread is released after removing the thread from the object to be sewing, it is possible to easily change the thread at the time of stopping the sewing machine or to thread the thread.

According to the invention of claim 2, it is possible to detect whether the wiper has returned to its original position, and the needle breaks due to contact with the center presser foot or contact with the sewing needle due to the wiper not returning to the original position. Can prevent losing.

In addition, since the state of the wiper can also be determined by the detection of the thread catching spring, a dedicated sensor for detecting whether the wiper is returned to its original position is unnecessary.

Claims (2)

A sewing needle for inserting a thread into the needle hole formed at the tip and sewing the sewing object placed on the needle plate by Shanghaidong, A thread cutting device disposed below the needle plate and cutting the thread after finishing sewing; A wiper for moving across the sewing needle and the sewing object to remove the thread cut by the thread cutting device from the sewing object; A sewing machine having a thread tensioning means for imparting tension to the thread, Mounting force which gives tension to the thread when the thread is removed from the sewing object by the wiper and controls the operation of the mounting force imparting means to release the tension applied to the thread when the thread is removed from the sewing object. Sewing machine comprising a control means. The method of claim 1, A thread catching spring provided on the path of the thread from the thread supply source to the needle hole, the thread catching spring being elastically deformed by the tension of the thread at the same time as the thread is hanging; And a sensor for detecting the presence of the thread catching spring at an initial position before the tension of the thread acts on the thread catching spring, And a sewing needle control means for stopping the vertical operation of the sewing needle when the sensor does not detect the thread catching spring after the wiper crosses between the sewing needle and the sewing object. .

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