JP2002126387A - Sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To draw out an end of an upper thread to the rear side of cloth, limiting the amount of the upper thread drawn out at a first stitch by means of a simple construction, and to prevent the upper thread from being pulled out when the cloth is taken out by limiting the amount of the upper thread drawn out when a sewing needle stops at an upper dead point after the thread is cut off. SOLUTION: An engaging pin 5, which can be projected, is provided on the front surface HF of a head H of a sewing machine. After thread cutting, and before a sewing needle 1 moves to an upper dead point, the pin 5 is projected to engage an upper thread T hanging from a balance 4. Even if the machine begins to operate, the pin 5 is held in projected state, and when the balance comes down once and then rises and reaches the upper dead point, the pin 5 is retracted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewing machine capable of limiting the amount of needle thread to be fed.

[0002]

2. Description of the Related Art Conventionally, the upper thread end at the start of sewing has been sewn to the back side of a fabric from the viewpoint of emphasizing the beauty of sewing.

As such a technique, there is known a sewing machine disclosed in Japanese Patent Application Laid-Open No. 62-186892, in which the upper thread is pulled out toward the back side of the fabric at the first stitch by limiting the amount of the thread delivered. ing.

[0004] That is, this sewing machine is provided below the balance and has a thread pinch for clamping the upper thread between the balance and the sewing needle. When the looper point catches the upper thread loop, the upper thread is clamped and sewn. Since the supply of the upper thread to the needle is stopped, the upper thread end extending from the sewing needle is pulled downward through the sewing product and the needle plate hole by the subsequent drawing of the loop by the rotation of the looper tip.

[0005]

However, such a conventional sewing machine has a problem that the structure is complicated and the cost is high because the structure is such that the upper thread is clamped. Further, the thread pinch needs to be minimized in order to minimize the contact area with the upper thread so as not to affect the sewing, so that it must be miniaturized and the cost must be increased because dense parts must be used. was there.

Further, since the conventional sewing machine has a configuration in which the upper thread is clamped, the operator has to pass the upper thread so as to be clamped between the thread clamps, and there is a problem that the workability is poor.

[0007] By the way, conventionally, it has been practiced to secure a rising amount of the presser so as to facilitate the handling of the cloth under the presser, and accordingly, it is necessary to secure a rising amount of the sewing needle. Have been done. Specifically, the sewing machine usually stops when the balance comes to the top dead center when thread trimming is performed, but since the sewing needle is located below the top dead center as it is, the sewing machine upper shaft is Is rotated in the reverse direction to raise the sewing needle and move to the top dead center.

However, when the sewing machine upper shaft is rotated in the reverse direction to raise the sewing needle and move to the top dead center, the balance is lowered, so that the upper thread is loosened between the balance and the sewing needle. Therefore, at this time, if the cloth is to be taken out after the completion of the thread cutting, there is a problem that the slack upper thread is pulled together with the cloth and the upper thread end extending from the sewing needle becomes longer than necessary. . In the conventional sewing machine, since this problem is not described at all, there is naturally a problem that the upper thread end becomes longer.

Accordingly, the present invention provides a sewing machine which, with a simple structure, restricts the amount of the upper thread to be fed to the first stitch and pulls out the upper thread end toward the back side of the fabric. Provided is a sewing machine that restricts the amount of the upper thread to be drawn out and prevents the upper thread from being pulled out when taking out the fabric.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a sewing machine according to the first aspect of the present invention has a thread passing hole through which an upper thread is supplied from an upper thread supply source. A moving balance, a sewing needle which inserts a needle thread from the balance into a needle hole and moves up and down in conjunction with the balance, and a needle point for hooking a loop formed near a needle hole of the sewing needle; And a shuttle interlocking with the balance, wherein the upper thread passing through the threading hole is provided so as to be able to advance and retreat on a traversing path traversed by the vertical movement of the balance, and locks the upper thread on the upper surface at the time of advancement and the upper thread at the time of retreat. A locking member for releasing the locking, a driving means for moving the locking member forward and backward, and such that the hook member of the shuttle advances at the first stitch to advance the locking member to lock the upper thread. And control means for controlling the driving means.

Thus, before the hook point of the shuttle hooks the loop at the first stitch, the control means advances the locking member by the driving means and locks the upper thread on the upper surface of the locking member. Supply is limited. The upper thread is pulled when the loop is widened so that the loop hooks through the hook hooked by the sword, but the upper thread on the balance side of the sewing needle is restricted, so the upper thread on the end side is restricted. Is pulled, so that the upper thread end side is pulled out below the fabric.

[0012] Therefore, the pulling out of the upper thread end at the first stitch below the fabric can be achieved by a simple structure in which the locking member moves forward and backward, so that the cost can be reduced. Further, since the locking member only locks the upper thread on the upper surface thereof, there is no need to pass the upper thread through the thread pinch, and the workability is good.

According to a second aspect of the present invention, in the sewing machine according to the first aspect, the locking member is configured to lock the upper thread near the top dead center of the balance.

Thus, since the locking member locks the upper thread near the top dead center of the balance, the supply of the upper thread to the sewing needle at the first stitch is minimized.

[0015] Therefore, the upper thread end can be reliably drawn down the fabric.

According to a third aspect of the present invention, in the sewing machine according to the first aspect, the locking member locks the upper thread on the upper thread supply source side.

[0017] Thus, the locking member locks the upper thread on the upper thread supply source side, so that the upper thread is pulled by lowering the balance as in the case of locking on the sewing needle side. It does not happen.

Therefore, the upper thread end does not come off from the needle hole of the sewing needle, and the labor for threading the operator can be saved.

According to a fourth aspect of the present invention, there is provided a sewing machine which has a threading hole through which an upper thread from an upper thread supply source is inserted, and which moves up and down; A sewing needle that moves up and down in conjunction with the sewing machine, the balance stops at approximately the top dead center after thread trimming, and thereafter, returns the sewing needle to the top dead center. Restraining means for restraining the upper thread, driving means for driving the restraining means, and driving means for restraining the upper thread before the thread-cut fabric is taken out from below the sewing needle. And control means for controlling the

Thus, before the thread-cut fabric is taken out from below the sewing needle, the control means drives the restraining means by the driving means to limit the supply of the upper thread to the sewing needle.

Therefore, the upper thread is not pulled out when the fabric is taken out from below the sewing needle, and the length of the upper thread remaining on the sewing needle can be optimized.

According to a fifth aspect of the present invention, in the sewing machine according to the fourth aspect, the restraining means is located near the top dead center of the balance, and the upper thread passing through the threading hole is traversed by the vertical movement of the balance. A locking member that is provided so as to be able to advance and retreat on the traversing path and locks the upper thread at the upper surface during advancement and releases the engagement when retreating, wherein the driving means advances and retracts the engagement member, and the control means includes Before taking out the thread-cut cloth from below the sewing needle, the driving means is controlled so that the locking member advances to lock the upper thread.

[0023] As a result, the upper thread is locked on the upper surface by the advancement of the locking member in the vicinity of the top dead center of the balance, so that the supply of the upper thread to the sewing needle is suppressed, and the cloth is placed below the sewing needle. The upper thread is not pulled out together with the thread when it is taken out of the machine.

Therefore, it is possible to prevent the upper thread from being pulled out in taking out the fabric with a simple structure in which the locking member moves forward and backward, so that the cost can be reduced.

According to a sixth aspect of the present invention, in the sewing machine according to the first or fifth aspect, the control means is configured to advance the locking member by the driving means when the balance is stopped. are doing.

Thus, when the locking member advances, the balance is stopped and the upper thread is stationary, so that the locking member comes to a desired position with respect to the upper thread.

Therefore, the upper thread can be reliably locked on the upper surface of the locking member.

According to a seventh aspect of the present invention, in the sewing machine according to the first or fifth aspect, when the balance is positioned substantially above the locking member, the control means controls the locking member by the driving means. Is configured to retreat.

Thus, when the locking member is retracted, the balance is located substantially above the locking member, so that the upper thread is not loosened.

Therefore, the loose upper thread does not become entangled with parts around the balance or the balance itself.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> As shown in FIG. 1, a sewing machine 100 according to the present invention is provided opposite to a bed B on which a cloth to be sewn is placed. A sewing machine head H is provided, and has the following configuration.

The sewing needle 1 has a needle hole 1a near the lower end for inserting the upper thread T, and is fixed to a needle bar 2 whose upper end moves up and down. The thread guide 3 is provided at the lower end of the jaw portion HA of the sewing machine head H, and guides the upper thread T to the sewing needle 1.

The balance 4 has a threading hole 4a through which the upper thread T is inserted.
And swings up and down along a long hole H1 formed vertically above the thread guide 3 and to the right on the front face HF of the sewing machine head H. The threading hole 4a is formed so as to communicate in the left-right direction (the direction perpendicular to the long hole H1) in FIG. In FIG. 1, the balance 4 is located at the top dead center.

The locking pin 5 is provided so as to be able to advance and retreat from the front face HF of the sewing machine head H slightly below the thread spool side of the balance 4 at the top dead center. When the locking pin 5 advances, the upper thread T, which is passed over the threading hole 4a of the balance 4 and a thread tensioner 7 described later, is positioned on a traversing path traversed by the vertical swing of the balance 4. Then, the upper thread is locked on the upper surface thereof, and the upper thread is released, so that the lock of the upper thread is released. The thread locking pin 5 constitutes a locking member and a restraining means. Also,
The thread spool has a long winding of the upper thread and serves as an upper thread supply source.

Here, the structure of the locking pin 5 and the entire locking device K including the locking pin 5 will be described in detail.

As shown in FIG. 2, the locking pin 5 is
From the rear to the rear HR. A base end of the locking pin 5 is connected to a rod 6a of the air cylinder 6, and a washer 5a is fixed near the base end. A return spring 5b is provided between the washer 5a and the back HR,
The washer 5a is always urged rightward.

When air is supplied to the air cylinder 6, the rod 6a advances leftward, and the locking pin 5 moves the return spring 5b.
To the left to advance the front end from the front HF, and the front end of the locking pin 5 advances to a position beyond the threading hole 4a of the balance 4. At this time, as shown in FIG. 1, the locking pin 5 enters just below the upper thread T on the balance 4 at the top dead center. When the supply of air to the air cylinder 6 is stopped, the return spring 5b presses the washer 5a to the right, the locking pin 5 moves to the right, and the tip retreats. Retreat to a position flush with the front HF.

The driving means is constituted by the balance return spring 5b and the air cylinder 6. 1 and 2, the locking pin 5 is in the advanced state.

Returning to FIG. 1, the thread tensioner 7 is provided on the right side and below the long hole H1 and guides the upper thread T from the thread spool as the upper thread supply source to the balance 4. The thread tension 7 can hold the upper thread T between the thread tension discs 7a and 7b and apply a predetermined tension to the upper thread T.

The needle plate 10 has a needle plate hole 10a through which the sewing needle 1 passes.
The bed is provided flush with the bed B, and cloth (not shown) is placed on the upper surface thereof.

Although not shown, an upper shaft rotated by driving a sewing machine motor M (see FIG. 3) and a needle connected to the upper shaft and driven to move the needle bar 2 up and down are provided in the sewing machine head H. A bar vertical movement mechanism and a balance swinging mechanism that is connected to the upper shaft and driven to swing the balance 4 up and down are provided. That is, since both the needle bar 2 and the balance 4 are connected to the upper shaft, the sewing needle 1 fixed to the needle bar 2 and the balance 4 are in an interlocking relationship.
Further, in the bed B, a shuttle 11 (see FIG. 5) for forming a seam in cooperation with the sewing needle 1 below the needle plate 10 is provided. The shuttle 11 is also connected to and driven by the upper shaft. Therefore, the sewing needle 1, the balance 4, and the shuttle 11 are in an interlocking relationship.

Although not shown, the bed B is provided with a thread trimming device driven by a thread trimming drive source 16 (see FIG. 3). After the sewing is completed, the upper thread and the lower thread are cut. I have.

Next, the control block will be described with reference to FIG.

Reference numeral 12 denotes a control means, a ROM for storing a control program and control data necessary for the sewing operation, a RAM for storing data to be rewritten and data to be temporarily stored, and a program for executing the control program. CPU.

Reference numeral 13 denotes a start switch, for example,
It is constituted by a push button, and when pressed, sends a start signal to the control means 12 to start the sewing operation.

E is a needle position detecting means, which is constituted by, for example, a rotary encoder, is connected to the upper shaft,
The control means 12 outputs a rotation position signal corresponding to the rotation position of the upper shaft.
Send to Thereby, the vertical position of the needle bar 2 linked to the upper shaft can be detected.

The air cylinder 6 is connected to the control means 12 via an electromagnetic valve 14, and the control means 12
The air supply from the air supply source to the air cylinder 6 is controlled by opening and closing the air cylinder 4.

The sewing machine motor M is connected to the control means 12 via a driver 15, and the control means 12 controls the rotation of the sewing machine motor via the driver 15.

Reference numeral 16 denotes a thread cutting drive source, and a driver 17
Is connected to the control means 12 through the
Controls the driving of the thread cutting drive source via the driver 15.

Next, the operation will be described with reference to FIGS.

The needle bar 2 and the balance 4 interlock with the rotation of the upper shaft.
Operate in a phase relationship as shown in FIG. FIG. 5 shows the relationship between the balance, the sewing needle, and the shuttle, corresponding to (a) to (e) in FIG.

When the sewing is completed, the thread trimming drive source 16 is driven during the thread trimming section, and the upper thread T and the lower thread are trimmed.

When the needle position detecting means E detects the position of the needle bar 2 corresponding to the top dead center of the balance 4 after the completion of the thread trimming, the upper shaft is stopped and the operation of the sewing machine is stopped. (FIG. 5
(B) Related).

Thereafter, the air cylinder 6 is driven to advance the locking pin 5, and the tip of the locking pin 5 is moved to a position immediately below the upper thread T on the balance 4 as shown in FIG. At this time,
Since the balance 4 is stopped, the locking pin 5 is securely connected to the upper thread T.
Can be entered directly below.

Next, as shown in FIG. 5 (a), the upper shaft is reversed in the reverse rotation section so that the fabric can be easily handled, and the needle bar 2 is moved to the top dead center by the needle position detecting means E. When it is detected that there is, the reverse rotation of the upper shaft is stopped. Thereafter, the operation of the sewing machine is stopped until the start switch 13 is pressed, and a stop section is set. During the stop section, the fabric is taken out from below the sewing needle 1. However, as shown in FIG. 5A, the upper thread T is locked on the upper surface of the engagement pin 5 and the downward movement is restricted. In addition, the upper thread T is not pulled out together with the fabric, and the length of the upper thread remaining on the sewing needle 1 can be appropriately maintained.

Thereafter, when the start switch 13 is depressed, a start signal is outputted to the control means 12, and the control means 12 starts the operation of the sewing machine including the driving of the sewing machine motor M via the driver 15, and the operation section Move to.

That is, when the operation is started, FIG.
As shown in (b), the sewing needle 1 is lowered and the balance 4
Moves up to the top dead center. Then, FIG.
As shown in (c), the sewing needle 1 reaches the bottom dead center and the balance 4 descends. At this time, since the upper thread T is locked by the upper surface of the locking pin 5, the upper thread is maintained in a stretched state without being loosened by the lowering of the balance 4.

Subsequently, when the sewing needle 1 starts to rise from the bottom dead center, a loop L is formed near the tip of the sewing needle 1 as shown in FIG. Rushes, whereby the blade point 11a can hook the loop L. Thereafter, when the shuttle 11 is rotated, FIG.
As shown in (e), the loop L is expanded so that the shuttle 11 passes through the loop L. However, since the upper thread T is locked on the upper surface of the locking pin 5, the thread on the sewing needle 1 side is used. Is not pulled, but pulls the yarn on the yarn end side and pulls out the upper yarn end TE below the fabric and the needle plate hole 10a. FIG. 5 (e) shows a state in which the sewing needle 1 has risen from the state of FIG. 5 (d) and the upper thread end TE has been pulled out of the cloth at the timing when the balance 4 has reached the bottom dead center. However, the timing is not limited to this, and as shown in FIG. Could be

Thereafter, as shown in FIG. 5A, the sewing needle 1 moves to the top dead center again, and as shown in FIG. 5B, the balance 4 moves to the top dead center. When the position detecting means E detects the position of the needle bar 2 corresponding to the top dead center of the balance 4, the locking pin 5 is retracted. As described above, since the locking pin 5 is retracted when the balance 4 moves to the top dead center, the upper thread T after the locking pin 5 retracts is not loosened, and It does not get caught on peripheral parts.

After the locking pin 5 is retracted, sewing is performed in the same manner as in the prior art. After thread cutting, the locking pin 5 is advanced again and the needle bar 2 is moved to the upper dead point as described above. Stop the sewing machine and wait for the start switch 13 to be pressed.

The sewing machine according to the first embodiment has a locking pin 5
Is such that after the locking pin 5 retreats, the tip does not come into contact with the upper thread T, so that the upper thread does not come into contact with the upper thread. Can be prevented from being entangled.

Further, the sewing machine according to the first embodiment is a simple operation in which one member such as the locking pin 5 is moved forward and backward only once to prevent the upper thread from being pulled out at the time of taking out the fabric after the thread cutting. Two effects of preventing the upper thread from being pulled out at the first stitch at the start of sewing can be obtained. <Second Embodiment> A second embodiment will be described with reference to FIG.

The second embodiment is the same as the first embodiment except that the arrangement of the locking device K is different.

More specifically, as shown in FIG. 6, the locking pin 5 is arranged on the sewing needle side opposite to the thread spool with respect to the long groove H1 and substantially near the vertical center of the long groove H1.

Here, the vertical position will be described in more detail.

As shown in FIG. 6, the vertical position of the locking pin 5 is slightly lower than the vertical position at which the balance 4 is located when the sword 11a of the shuttle 11 hooks the loop L, and the locking pin 5 has advanced. Is a position where it enters just below the upper thread T hanging on the balance 4.

With such a configuration, when the balance 4 descends and is located at the upper right of the locking pin 5 after the start of sewing, the locking pin 5 is advanced to enter the position immediately below the upper thread T, and the locking is performed. The upper thread T is locked by the upper surface of the pin 5. At this time, the shuttle 11 is hooked on the loop L by the sword 11a. Thereafter, the shuttle 11 continues to rotate and unfolds the loop L so as to pass through the loop L. However, since the upper thread T is locked on the upper surface of the locking pin 5, the thread on the sewing needle 1 side is not pulled. , Pull the yarn on the yarn end side to make the upper yarn end TE
a can be pulled downward.

In the second embodiment, the timing at which the locking pin 5 advances is when the balance 4 is positioned at the upper right of the locking pin 5, but is not limited to this timing. May be at a timing at which it enters below the upper thread T hanging on the balance 4.

The vertical position of the locking pin is set near the top dead center in the first embodiment and near the center of the long groove in the second embodiment. However, the present invention is not limited to this.
Any position is acceptable as long as the locking pin, which has been advanced before the hook of the hook hooks the loop, can enter under the upper thread hanging on the balance. More specifically, the position may be within an area where the position of the locking pin in the first embodiment is the upper limit and the position of the locking pin in the second embodiment is the lower limit. However, the upper pin can lock the upper thread at an earlier stage if the locking pin is on the upper side, so the supply of the upper thread to the sewing needle is minimized,
The upper thread end can be reliably pulled down the fabric.

In the first embodiment, the left and right positions of the locking pin with respect to the balance are on the thread spool side, and in the second embodiment, on the sewing needle side. When the balance is on the side, the upper thread is pulled out slightly from the thread spool by the lowering of the balance. On the other hand, when it is on the sewing needle side, it is hardly pulled out, or on the contrary, the thread on the sewing needle side is pulled in. Has to do with it. That is, the first
When the locking pin is at the top as in the embodiment, the sewing needle descends while the upper thread is locked, and if the upper thread is not pulled out at this time, the upper thread passes through the needle hole of the sewing needle. In this case, the upper thread can be prevented from coming off from the sewing needle by disposing the locking pin on the thread spool side. Also, when the locking pin is below as in the second embodiment, the locking pin locks the upper thread shortly after,
Since the upper thread end is about to be pulled out by spreading the hooked loop around the hook, the upper thread end cannot be pulled out if the upper thread is pulled out from the balance side at this time. In this case, the upper thread end can be reliably pulled out by arranging the locking pin on the sewing needle side. Therefore, if the upper thread is to be locked before the sewing needle reaches the vicinity of the bottom dead center, it is desirable to arrange the locking pin on the thread spool side. In this case, it is desirable to arrange the locking pin on the sewing needle side.

Another modification of the sewing machine which moves the sewing needle to the top dead center after thread trimming and stops the needle, and prevents the upper thread from being pulled out when the fabric is taken out from below the sewing needle is disclosed in Japanese Patent Application Laid-Open No. H11-157572. As shown in JP-A-62-186892, a thread pinch is provided below the balance and between the balance and the sewing needle, and after thread trimming, the thread pinch is driven to pinch and restrain the upper thread. It may not be drawn out to. However, in the case of this configuration, since the upper thread is in a slack state near the balance, when the sewing machine is operated, there is a fear that the loose upper thread may be caught on a part around the balance, for example, the thread tension, Not preferred. In this case, the thread pinch constitutes a restraining means.

The present invention is not limited to the above embodiment, and it goes without saying that changes can be made without departing from the spirit of the invention.

[Brief description of the drawings]

FIG. 1 is an enlarged schematic front view of the vicinity of the head of a sewing machine according to the present invention.

FIG. 2 is a partially enlarged side view of the head of the sewing machine of the present invention.

FIG. 3 is a control block diagram of the present invention.

FIG. 4 is a time chart of the present invention.

FIG. 5 is a diagram showing the relationship between the balance of the present invention, a sewing needle and a shuttle.

FIG. 6 is a diagram showing the relationship between the arrangement of locking pins and the timing of a shuttle when the upper thread is locked according to the second embodiment.

[Explanation of symbols]

100 ... sewing machine 1 ... sewing needle 2 ... needle bar 3 ... thread guide 4 ... cloth presser 5 ... locking pin ( Locking member, restraining means 6 Air cylinder (drive means) 7 Thread tension 10 Needle plate H Sewing machine head B Bed T ・ ・ ・ ・ ・ ・ ・ Upper thread

Claims (7)

[Claims] 1. A balance which has a threading hole for inserting a needle thread from a needle thread supply source and which moves up and down, and a sewing needle which inserts an upper thread from the balance into a needle hole and moves up and down in conjunction with the balance. And a sewing machine having a hook that hooks a loop formed near the needle hole of the sewing needle, and a shuttle that is interlocked with the sewing needle and the balance. The upper thread passing through the threading hole is traversed by vertical movement of the balance. A locking member that is provided on the traversing path so as to be able to advance and retreat, and that locks the upper thread at the upper surface at the time of advance and releases the engagement at the time of retreat; A sewing machine comprising: control means for controlling a driving means so as to advance the locking member and lock the upper thread before the sword hooks the loop. 2. The sewing machine according to claim 1, wherein the locking member locks the upper thread near a top dead center of the balance. 3. The sewing machine according to claim 1, wherein the locking member locks the upper thread on the upper thread supply source side. 4. A balance having a threading hole for inserting a needle thread from a needle thread supply source and moving up and down, and a sewing needle which inserts an upper thread from the balance into a needle hole and moves up and down in conjunction with the balance. The sewing machine returns the sewing needle to the top dead center after the thread trimming, and the sewing machine returns the sewing needle to the top dead center.The sewing machine is provided between the sewing needle and the upper thread supply source to restrain the upper thread. Restraining means, driving means for driving the restraining means, and control means for controlling the driving means so that the restraining means restrains the upper thread before removing the thread-cut fabric from below the sewing needle. A sewing machine characterized by the following. 5. The sewing machine according to claim 4, wherein the restraining means is located near the top dead center of the balance, and is capable of moving back and forth on a crossing path through which the upper thread passing through the threading hole traverses by vertical movement of the balance. A locking member that locks the upper thread on the upper surface at the time of advance and releases the lock at the time of retreat, wherein the driving means advances and retreats the locking member, and the control means performs thread cutting. A sewing machine wherein a driving member is controlled so as to advance a locking member and lock an upper thread before taking out a cloth from below a sewing needle. 6. The sewing machine according to claim 1, wherein said control means advances said locking member by driving means when said balance is stopped. 7. The sewing machine according to claim 1, wherein the control means retreats the locking member by a driving means when the balance is positioned substantially above the locking member. sewing machine.