JP3594735B2 - Sewing machine thread trimmer - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thread trimming device of a sewing machine that performs a thread trimming operation based on thread trimming operation information from a thread trimming cam.
[0002]
[Prior art]
Generally, a thread trimming operation of a sewing machine is performed by operating a thread trimming knife with a thread trimming cam rotated together with a main shaft. That is, when performing thread trimming, the link input portion of the thread trimming mechanism is pressed against the cam surface provided on the thread trimming cam, and the thread trimming operation information from the thread trimming cam is transmitted to the moving knife via the link mechanism. , The moving knife is rotated to cut the thread between the moving knife and the fixed knife.
[0003]
On the other hand, there has been conventionally known a technique in which a thread clamping pressure of a thread tension disc is relaxed by a disc loosening mechanism at the time of such a thread trimming operation to reduce the tension of the thread so that the thread trimming operation can be performed without any trouble. As a dish loosening mechanism for performing such a dish loosening operation, a mechanism having various configurations has conventionally been proposed.
[0004]
[Problems to be solved by the invention]
However, in the conventional plate loosening mechanism, since the synchronous relationship with the thread trimming mechanism is not strictly taken, especially when the sewing speed is high, thread trimming failure occurs or sewing is restarted after thread trimming. In some cases, sewing failure may occur.
[0005]
In view of the above problems, the present invention provides a sewing machine that can perform a thread trimming operation satisfactorily even in high-speed sewing and can resume sewing after thread trimming in a good state. It is an object to provide a thread cutting device .
[0006]
[Means for Solving the Problems]
In order to achieve the above object, in the invention according to claim 1, a thread cutting cam fixed to a main shaft having a cam surface on which information for performing a thread cutting operation is formed , based on the thread cutting operation information, and the thread cutting mechanism to perform a thread cutting operation to the thread cutting knife, a dish loosening mechanism loosen Itokyo pressure of the thread tension discs during thread cutting operation by the thread cutting knife, the upper Symbol thread cutting In the thread trimming device of a sewing machine having a dish loosening notch that rotates integrally with the cam, and a link mechanism that transmits thread loosening operation information from the dish loosening notch to the thread tension disc side, the cam surface of the thread trimming cam may be provided. A thread trimming roller disposed so as to be able to abut, and a thread trimming roller is disposed between an inoperative position in which the thread trimming roller abuts a cam surface of the thread trimming cam and a non-operation position in which the thread trimming roller is axially separated; Reciprocating and rotatable on substantially parallel axes A cam follower arm disposed, wherein the countersunk release notch is disposed so as to project radially outward from an outer peripheral surface of the thread trimming cam; A thread loosening plate having an arm portion which is reciprocally movable with the cam driven arm on one axis so as to engage with the dish loosening notch at the execution position and is separated at the non-operation position together with the cam driven arm, and is rotatable on the one axis. An L-shaped link abutting on an arm portion of the thread-releasing plate so as to convert a rotational operation of the thread-releasing plate about a horizontal axis into a rotational motion about a vertical axis; A connection member for relaxing the thread clamping pressure of the thread tension disc according to rotation in a horizontal plane about the axis .
[0008]
In such a thread trimming device for a sewing machine according to the first aspect , the thread trimming mechanism and the plate loosening mechanism are synchronized with the thread trimming cam rotated integrally with the main shaft by the main shaft interlocking means. A series of thread trimming operations are performed based on a strict synchronous relationship, and therefore, even when the sewing speed is high, a good thread trimming operation can be accurately performed.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiment shown in FIG. 1, first, a thread cutting cam 1 constituting a thread cutting mechanism is fixed to a main shaft (upper shaft) not shown, and a rear end face of the thread cutting cam 1 in the axial direction. A cam surface (not shown) is annularly formed in a groove shape on the (rear side of the back side in the figure). On the grooved cam surface, information for causing a thread trimming knife described later to perform a predetermined thread trimming operation is formed in an uneven shape.
[0010]
The thread trimming shaft 2 is disposed substantially in parallel with the main shaft so as to be adjacent to the main shaft. The base end side (front side in the figure) of the cam driven arm 3 is provided on the thread trimming shaft 2 with a boss. It is fixed at 3a. That is, the cam driven arm 3 is configured to reciprocate in the axial direction together with the thread cutting shaft 2 and to rotate together with the thread cutting shaft 2, and to extend from the base end side of the boss 3 a above the main shaft. It extends almost horizontally across the side. As will be described later, the position where the cam driven arm 3 moves forward in the drawing is the thread cutting execution position, and the position where the cam driven arm 3 is retracted to the back in the drawing is the thread cutting standby position.
[0011]
Further, a thread cutting return spring 4 is mounted in a compressed state on a front end portion (a portion on the front side in the figure) of the thread cutting shaft 2. The cam follower arm 3 is pushed to the rear end side (rear side in the figure).
[0012]
On the other hand, a thread cutting roller shaft 5 is provided upright in the middle of the cam driven arm 3 in the extending direction, and the thread cutting roller 6 is rotatable with respect to the thread cutting roller shaft 5. It is attached to. The thread cutting roller 6 is brought into contact with the cam surface of the thread cutting cam 1 described above. However, usually, the urging force of the thread cutting return spring 4 described above and the cam driven arm 3 at the rear side (the inner side in the drawing). Side), is separated from the cam surface of the thread trimming cam 1 in the axial direction, and stands by in a non-contact state (non-operating state).
[0013]
Above the cam driven arm 3, a cam driven stopper plate 7 is fixed substantially horizontally to a machine frame (not shown). At the front edge of the cam driven stopper plate 7, a locking projection 7a is provided so as to protrude by a predetermined amount in the axial direction. The engagement projection 3b provided on the base end side of the arm 3 is configured to be able to abut from the front side in the axial direction.
[0014]
More specifically, when the cam driven arm 3 moves forward to the thread trimming execution position in the drawing, the engaging protrusion 3b of the cam driven arm 3 comes into contact with the locking protrusion 7a of the cam driven stopper plate 7. Thus, the thread trimming execution state, that is, the state where the thread cutting roller 6 is in contact with the cam surface of the thread cutting cam 1 is maintained. On the other hand, when the thread driven operation is completed and the cam driven arm 3 is rotated, the engaging protrusion 3b of the cam driven arm 3 is disengaged from the locking protrusion 7a of the cam driven stopper plate 7, and the above-described operation is performed. By the urging force of the thread cutting return spring 4, the cam follower arm 3 is retracted to the non-operation position to the rear side in the drawing.
[0015]
Further, a center portion of the thread cutting magnet arm 8 is pivotally attached to the cam driven stopper plate 7 so as to rotate in a substantially horizontal plane. The thread cutting magnet arm 8 is disposed so as to cross the upper side of the main shaft, and the hook 8 a formed at one end side of the thread cutting magnet arm 8 on the near side in the drawing is connected to the cam driven arm 3 described above. Are engaged in the axial direction from the rear side (the rear side in the figure) with the engagement protrusion 3b.
[0016]
A thread cutting solenoid 11 is fixed to the machine frame (not shown) via a mounting bracket 9 at a position rearward of the other side of the thread cutting magnet arm 8 in the back side of the figure. The output shaft 11a is rotatably connected to the illustrated rear end 8b of the thread cutting magnet arm 8. When the output shaft 11 a is retracted by turning on the thread cutting solenoid 11, the thread cutting magnet arm 8 is rotated in a substantially horizontal plane, and the hook portion 8 a of the thread cutting magnet arm 8 causes the cam to rotate. The engagement projection 3b of the driven arm 3 is configured to be pushed forward (toward the illustrated side).
[0017]
Further, an upper end portion of a thread cutting connecting rod 12 extending in a substantially vertical direction is rotatably pivoted to an extended end portion (a rear end portion in the drawing) of the cam driven arm 3. The lower end portion of the thread cutting connecting rod 12 is rotatably connected to a rear end side of the thread cutting connecting rod 14 extending substantially horizontally via an L-shaped link 13. The thread cutting connection rod 14 is configured to reciprocate in a substantially horizontal axial direction by vertical movement. At this time, a thread cutting link spring 15 is attached in a tensioned state at an intermediate portion of the thread cutting connecting rod 14, and the thread cutting link rod 15 is moved rearward in FIG. Is to be drawn into.
[0018]
A pin 17 constituting an input portion of a female link mechanism for rotating the moving knife 16 is rotatably connected to a front end portion of the thread cutting connecting rod 14 on the near side in the drawing. When the moving knife 16 is rotated by the horizontal movement of the connecting rod 14, the thread is cut between the moving knife 16 and the fixed knife 18.
[0019]
On the other hand, a thread loosening notch plate 21 composed of an arc plate having a circumferential length of about 1/4 is attached to the axial front end surface (the front surface in the drawing) of the thread cutting cam 1 described above. The thread loosening notch plate 21 constitutes a part of a dish loosening mechanism for performing a predetermined thread loosening operation with respect to a thread tension plate 22 described later. The thread trimming cam 1 is arranged so as to project radially outward from the outer peripheral surface.
[0020]
Further, a center portion of a substantially L-shaped thread loosening plate 23 is fixed to an intermediate portion of the thread cutting shaft 2 described above, and is configured to rotate together with the cam driven arm 3. The thread loosening plate 23 is provided so as to reciprocate in the axial direction together with the cam driven arm 3, and has a horizontal arm portion 23a extending above the main shaft and a vertical arm portion 23b extending downward. And A thread-releasing arm pin 24 is fixed to the tip of the horizontal arm 23a so as to protrude forward in the axial direction.
[0021]
The thread loosening arm pin 24 is disposed so as to face the outer peripheral surface of the thread loosening notch plate 21 in the axial direction, and is normally separated from the thread loosening notch plate 21 in the axial direction. When the thread loosening plate 23 is moved forward (to the front in the figure) together with the arm 3, the thread loosening arm pin 24 is disposed at an axial position where it can ride on the outer peripheral surface of the thread loosening notch plate 21. Has become.
[0022]
The lower end portion of the vertical arm portion 23b of the thread loosening plate 23 is in contact with the middle portion of the arm of the L-shaped link 25 supported so as to rotate in a substantially horizontal plane. One end of a thread loosening connecting rod 26 extending substantially horizontally is rotatably connected to the arm tip of the arm 25. That is, when the thread loosening plate 23 is rotated in the vertical plane together with the cam driven arm 3, the turning operation of the thread loosening plate 23 in the vertical plane is performed through the L-shaped link 25. 26 is reciprocated in the horizontal direction.
[0023]
Further, the other end side (the front end side in the figure) of the thread loosening connection rod 26 is connected to one end side of a thread tension connection rod 28 via a connection adjustment section 27. The horizontal movement of the thread loosening connecting rod 26 causes the reciprocating movement in the horizontal direction. The thread tension connecting rod 28 is formed of a bent link extending substantially horizontally, and a front end side portion (a front side portion in the drawing) of the thread tension connecting rod 28 is slidably supported by a receiving plate 29. ing.
[0024]
Further, a thread loosening pin 31 is disposed at a front end side portion (a front side portion in the drawing) of the thread tension connecting rod 28 so as to abut substantially vertically, and the thread loosening pin 31 is provided at a contact portion of the thread loosening pin 31. , A step portion 28a as shown in FIG. 2 is formed. Then, with the front and rear reciprocating movement of the thread tension connecting rod 28, by the stepped portion 28a provided on the thread tension connecting rod 28 is reciprocally moved in the longitudinal direction, the thread loosening pins 31 thread tension regulator 32 It is configured to be reciprocated in the direction of the plate axis.
[0025]
As is well known, the thread tensioner 32 is configured to sandwich a thread between a pair of thread tension plates 22 at a predetermined pressure. The thread tensioner 32 is connected so that the thread clamping pressure of the thread tension plate 22 of the thread tensioner 32 is reduced when the thread tensioner 32 protrudes toward the side 32.
[0026]
As described above, the dish loosening mechanism according to the present embodiment is provided with the main shaft interlocking means for performing the operation of loosening the dish based on the operation of the thread trimming cam 1, and the synchronous relationship with the main shaft is controlled by the main spindle interlocking means. It is designed to be adopted in the same way as the mechanism.
[0027]
Next, a thread cutting method using such a thread cutting device will be described. When the sewing operation is completed and a thread trimming signal is issued from the sewing machine control device, the thread trimming solenoid 11 is turned on based on the thread trimming signal. As a result, the thread cutting magnet arm 8 is rotated, and the cam driven arm 3 is pushed forward (to the front in the drawing) against the thread cutting spring 4, and the thread cutting roller 6 provided on the cam driven arm 3. Are brought into contact with the cam surface of the thread cutting cam 1 formed on the thread cutting cam 1. As a result, the thread trimming operation information from the thread trimming cam 1 rotated together with the main shaft is converted into the vertical movement of the cam driven arm 3, and the vertical movement is further converted to the thread trimming connection rod 12, the L-shaped link 13, and the thread trimming linkage. The power is transmitted to the input section 17 of the female link mechanism via the rod 14 as horizontal rotation power. As a result, the moving knife 16 is rotated, and the thread is cut between the moving knife 16 and the fixed knife 18.
[0028]
When such a thread cutting operation is performed, the engaging protrusion 3b of the cam driven arm 3 is in contact with the locking protrusion 7a of the cam driven stopper plate 7, whereby the cam driven arm 3 is moved forward. It is held at the thread trimming execution position (on the near side in the figure). Therefore, even after the thread trimming solenoid 11 is turned off, the thread trimming roller 6 continues to contact the cam surface of the thread trimming cam 1 until the thread trimming operation is completed.
[0029]
On the other hand, by the turning action of the thread trimming magnet arm 8 by turning on the thread trimming solenoid 11, the thread loosening plate 23 is also pushed forward (toward the front side in the figure) together with the cam driven arm 3, whereby the thread loosening plate 23 is moved. The thread loosening arm pin 24 provided on the thread loosening notch plate 21 is disposed at a position where it can ride on the outer peripheral surface of the thread loosening notch plate 21.
[0030]
At the timing immediately before the above-described thread cutting operation by the moving knife 16 is performed, the thread loosening arm pin 24 rides on the outer peripheral surface of the thread loosening notch plate 21, whereby the thread loosening plate 23 rotates in the vertical plane. Be moved. The turning operation of the thread loosening plate 23 is transmitted as an acting force to the thread tension connecting rod 28 via the L-shaped link 25 and the thread loosening connecting rod 26. As a result, the step portion 28a provided at the front end side portion (the front side portion in the drawing) of the thread tension connecting rod 28 pushes out the thread loosening pin 31, and the thread loosening pin 31 is moved in the disc axis direction with respect to the thread tensioner 32. By being protruded, the thread clamping pressure of the thread tension disc 22 of the thread tensioner 32 is reduced. That is, the thread loosening operation is executed at an accurate timing in synchronization with the above-described thread cutting operation.
[0031]
As described above, in the sewing machine thread trimming apparatus and method according to the present embodiment, the thread trimming mechanism and the plate loosening mechanism are accurately controlled via the spindle interlocking means with respect to the thread trimming cam 1 which is integrally rotated with the main shaft. A synchronous relationship is adopted, and a series of thread cutting operations are performed based on a strict interlocking relationship. Therefore, even when the sewing speed is high, a favorable thread cutting operation is performed with high accuracy.
[0032]
On the other hand, in the sewing machine thread trimming method in the above-described embodiment, the sewing machine reverse rotation operation is performed before the sewing operation after the thread trimming operation is started. As the means for performing the reverse rotation operation, various means such as one in which the sewing machine motor reverses, one in which a motor for reverse rotation is separately provided, and one in which the rotation is mechanically reversed by a solenoid or the like can be adopted.
[0033]
More specifically, as shown in FIG. 3, a thread trimming operation is performed after the sewing operation is completed (steps 1 and 2), and when the needle bar reverse rotation is confirmed (step 3), the needle bar is rotated. The rotation is reversed (step 4). Thus, the needle at the upper stop position is returned to the top dead center position by reverse rotation. Dead center position location on the needle is detected by the position sensor of the main shaft. As a result, it is possible to easily take out and attach the sewing product.
[0034]
Furthermore, in the present embodiment, the first stitch of the sewing start after the above-described needle bar reverse rotation (Step 5) is performed by rotating the needle bar forward at the lowest sewing speed (for example, 400 SPM) (Step 6). Since the mechanism is returned to the thread trimming execution state by the above-described needle bar reversing operation, the thread loosening arm pin 24 of the thread loosening mechanism rides on the outer peripheral surface of the thread loosening notch plate 21 again. This is because the operation of loosening the dish of the thread tensioner 32 is performed again. That is, if the sewing operation is immediately executed at a high speed immediately after the loosening state of the plate after the reverse rotation operation, a problem such as a poor thread tightening may occur.
[0035]
Also, when the needle is returned to the vicinity of the top dead center due to the needle bar reversal, the balance (not shown) is returned to a position slightly lower than the top dead center, so that when the needle descends at the next sewing, The balance will rise once to the top dead center and then fall. Therefore, when sewing is started immediately at a high speed, the initial rising of the balance causes the thread end after thread trimming, which is derived from the needle, to be pulled in more than necessary, and the thread may come off from the needle, The amount of the thread drawn out from the needle hole of the needle is reduced, and the thread cannot be connected to the lower thread, which may cause a problem such as thread dropout or a knot defect at the start of sewing. Therefore, if the sewing operation is started at a low speed as described above, a satisfactory sewing operation can be obtained.
[0036]
The sewing operation is performed at the set speed for the second and subsequent stitches (step 7), and predetermined sewing is performed by, for example, XY drive. In steps 3 and 4, the sewing operation is started at the set speed even when the needle bar is not reversed.
[0037]
In such a sewing machine thread trimming method, the sewing operation is started at a low speed after the thread trimming operation is completed, so that the next sewing operation is satisfactorily restarted regardless of the thread trimming state. The sewing state is extremely good.
[0038]
Although the embodiment of the invention made by the inventor has been specifically described above, the present invention is not limited to the above embodiment, and it is needless to say that various modifications can be made without departing from the gist of the invention. Nor.
[0039]
【The invention's effect】
As described above, the thread trimming device of the sewing machine according to the present invention synchronizes the thread trimming operation and the plate loosening operation with the main shaft by the main shaft interlocking means with respect to the rotation of the thread trimming cam that is integrally rotated with the main shaft. , A series of thread trimming operations are executed based on a strict interlocking relationship, so that a good thread trimming operation can be accurately performed even when the sewing speed is high. Thus, the reliability of the thread cutting operation of the sewing machine can be improved.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a structure of a thread cutting device of a sewing machine according to an embodiment of the present invention.
FIG. 2 is an external perspective explanatory view showing an enlarged main part of a dish loosening mechanism.
FIG. 3 is a flowchart showing a basic procedure of a sewing operation according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Thread cutting cam 3 Cam driven arm 6 Thread cutting roller 7 Cam driven stopper plate 8 Thread cutting magnet arm 11 Thread cutting solenoid 16 Moving knife 18 Fixed knife 22 Thread tension plate 23 Thread loosening plate 24 Thread loosening arm pin 21 Thread loosening notch plate 28 thread tension connecting rod 28a step 31 thread loosening pin 32 thread tensioner

Claims (1)

A thread trimming cam having a cam surface on which information for performing a thread trimming operation is formed and fixed to a main shaft ;
Based on the thread cutting operation information from the thread cutting cam, a thread cutting mechanism to perform a thread cutting operation to the thread cutting knife,
A dish loosening mechanism that loosens the thread clamping pressure of the thread tension dish during the thread trimming operation by the thread trimming knife ;
And Sarah Loosen notch to rotate integrally with the top Symbol thread cutting cam,
A link mechanism for transmitting the thread loosening operation information from the disc loosening notch to the thread tension disc side;
A thread trimming device for a sewing machine having
A non-operating position having a thread trimming roller disposed so as to be able to abut on a cam surface of the thread trimming cam, and a thread trimming execution position at which the thread trimming roller abuts on a cam surface of the thread trimming cam and an axially separated position; A cam driven arm disposed reciprocally and rotatably on one axis substantially parallel to the main axis,
The dish loosening notch is arranged so as to project radially outward from the outer peripheral surface of the thread cutting cam,
The link mechanism,
The cam driven arm is reciprocally movable with the cam driven arm on one axis and rotatable on the one axis such that the cam driven arm is engaged with the plate loosening notch when in the thread trimming execution position and is separated when in the inoperative position. A thread loosening plate having an arm portion,
An L-shaped link abutting on the arm portion of the thread-releasing plate so as to convert the rotation of the thread-releasing plate about the horizontal axis to the rotation of the thread-releasing plate about the vertical axis;
A thread trimming device for a sewing machine, comprising: a connecting member that reduces thread clamping pressure of the thread tension disc according to rotation of the L-shaped link about a vertical axis in a horizontal plane .

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