CN1670287B - Thread tension adjusting device for sewing machine - Google Patents

Abstract

A sewing thread tension adjusting device for a sewing machine, which applies tension to the upper thread in the middle of the upper thread supply path from the thread supply source of the sewing machine arm composed of the front frame and the rear frame to the sewing needle through the thread take-up lever. The device includes: a thread tension adjustment shaft arranged on the front frame of the sewing machine arm; The pressing side clamping plate for pushing the pressing side clamping plate; the driving actuator for changing the tension applied to the upper thread through the pushed side and the pushing side clamping plate; The front end portion inside the thread tension adjustment shaft and the rear end side portion connected to the driving actuator and thicker than the front end side portion transmit the driving force of the driving actuator to the push side clamp The pushing force transmission member of the wire plate.

Description

Thread tension adjusting device for sewing machine

technical field

The present invention relates to a sewing thread tension adjusting device for a sewing machine that uses a driving actuator to change the tension applied to the upper thread formed by a pair of clamping plates arranged on the front frame of the sewing machine arm.

Background technique

Conventionally, various sewing machines such as lockstitch sewing machines and cycle sewing machines have been provided with various thread tension adjusting devices in order to adjust the tension applied to the needle thread. Recently, various automatic thread tension adjusting devices that do not manually adjust the thread tension but can be automatically adjusted using a solenoid actuator have been proposed and put into practical use.

Such as, in Japanese Patent Showa 56 years patent announcement No. 6314 communique (JP-B-56-6314), record a kind of control device of the thread take-up lever of the sewing machine of following structure: on the front frame of sewing machine arm, A thread clamp with a pair of tension plates is provided, and a magnet with an armature is provided on the inside of the sewing machine arm, and the front end of the armature pushes the thread clamp on the pressing side of the thread clamp from the inside to the outside of the sewing machine arm (For example, refer to Patent Document 1).

In the control device of the thread take-up lever of the sewing machine of this structure, because a magnet is arranged inside the sewing machine arm, there is a problem that when the magnet fails, the operator needs to insert the arm into the frame of the arm to replace the magnet. The replacement work is complicated and troublesome.

For this reason, in order to simplify the maintenance and replacement work of the solenoid actuator for thread tension adjustment, various proposals have been made in which the solenoid actuator is disposed outside the frame.

For example, in Japanese Patent Publication No. 210279 (JP-A-2002-210279) in 2002, as shown in Figures 4 to 8 of the accompanying drawings, a sewing thread tension adjusting device of a sewing machine with the following structure is described : On the front frame of the sewing machine arm, a thread tension adjustment seat for holding a thread tension adjustment shaft supporting a pair of clamping plates is provided. A cylindrical electromagnetic solenoid. When the electromagnetic solenoid is driven, the plunger moves in the direction of the clamping plates, and tension is generated by a pair of clamping plates.

But in this case, because the cylindrical electromagnetic solenoid is a structure that protrudes forward (user operation side) from the front frame of the sewing machine arm, there is a problem not only in the operation of hooking up the thread, but also in the There are also problems such as interference during sewing operations.

For this reason, in above-mentioned (JP-A-2002-210279), as shown in Fig. 16～Fig. 17 of accompanying drawing, describe a kind of suture tension adjusting device of the sewing machine of following structure: separate electromagnetic solenoid, Arranged on the outside of the rear frame of the sewing machine arm, the loosening pin inserted into the thread tension adjustment shaft supporting a pair of clamping plates is extended to the rear, and the electromagnetic helical thread is placed near the rear frame. The movable shaft of the tube is connected to the rear end of the thread release pin, so that the electromagnetic solenoid is driven by one of various driving voltages, so that the elastic force of the compressed coil spring can be changed, and the force applied to the thread can be changed. tension.

When the moving thread tension adjusting device shown in Fig. 16 and Fig. 17 of the above-mentioned JP-A-2002-210279 is adopted, the electromagnetic solenoid used for thread tension adjustment is set to the outside of the rear frame of the sewing machine arm. protruding shape. This facilitates the maintenance of the electromagnetic solenoid and replacement work at the time of failure. However, since the slender loosening pin inserted through the suture tension adjustment shaft is provided over the entire length from the front frame to the rear frame, the movable shaft is stretched out by the drive of the electromagnetic solenoid. , When the rear end of the thread release pin is pushed against the elastic force of the compression coil spring, the thread release pin is prone to deflection in the middle.

In this way, since the thread release pin deflects in the middle, there is a problem that the responsiveness of the front end of the thread release pin is deteriorated, and the tension acting between the pair of thread clamps cannot be finely controlled, causing the tension of the thread to decrease. The precision of the adjustment is reduced. For this reason, there is also a method of making the loosening pin thicker. However, if this is the case, the thread tension adjustment shaft through which the thread release pin with a thicker shaft diameter is inserted is also enlarged, and the thread tension adjustment device itself is enlarged and costly.

Contents of the invention

The object of the present invention is to provide a sewing thread tension of a sewing machine that can accurately transmit the pressing force to the pressing side tension plate without bending the pressing force transmission member in the middle, thereby improving the responsiveness and accuracy of tension adjustment. Adjustment device.

The sewing thread tension adjusting device of the sewing machine of the present invention applies tension to the upper thread at the middle part of the upper thread supply path from the thread supply source of the sewing machine arm composed of the front frame and the rear frame to the sewing needle through the thread take-up lever, It is characterized in that it includes: a thread tension adjustment shaft arranged on the front frame of the sewing machine arm; The pushing side tensioning plate that is pushed by the pushing side tensioning plate; the driving actuator for changing the magnitude of the tension applied to the upper thread through the pushed side and the pushing side tensioning plate; and having The front end portion inserted into the suture tension adjustment shaft and the rear end portion connected to the driving actuator and thicker than the front end portion transmit the driving force of the driving actuator to the The pushing force transmitting member that pushes the side bridge.

With this structure, when the driving force generated by the driving of the driving actuator is transmitted to the pressing side bridge through the pressing transmission member, since the rear end side part is thicker than the front end side part, the pressing force transmission member There is no deflection in the middle part, and the pushing force corresponding to the change of the driving force of the driving actuator can be accurately transmitted to the pressing side tension plate, and the responsiveness and accuracy of tension adjustment can be improved.

A brief description of the drawings

Fig. 1 is a perspective view seen from the left front of a lockstitch sewing machine in an embodiment of the present invention.

Fig. 2 is a longitudinal sectional side view of main parts of an arm portion of a lockstitch sewing machine.

Fig. 3 is an exploded perspective view of the suture tension adjusting mechanism.

Fig. 4 is a longitudinal sectional side view of main parts of the arm when the thread tension adjusting solenoid is driven.

FIG. 5 is a view corresponding to FIG. 3 of a modified example.

Detailed ways

As shown in FIG. 1 , the lockstitch sewing machine 1 is placed on a workbench T. As shown in FIG. A needle plate 5 is provided on the bottom plate portion 2 of the lockstitch sewing machine 1 . At the rear end portion of the bottom plate portion 2, a pillar portion 3 is erected upward. An arm portion (corresponding to a sewing machine arm) 4 extending forward is provided at an upper end portion of the pillar portion 3 so as to face the bottom plate portion 2 . In this case, the arm part 4 is comprised by the front part frame 4a and the rear part frame 4b (refer FIG. 2).

On the arm 4, there are provided: a needle bar driving mechanism for driving the needle bar 6 with the sewing needle 7 up and down by transmitting the driving force of the sewing machine motor (not shown) through the main shaft; A thread take-up lever drive mechanism for driving the thread lever 8 up and down; and a suture tension adjusting device 10 described later. Here, since the needle bar drive mechanism and the thread take-up drive mechanism are well-known techniques, detailed description thereof will be omitted.

Next, the thread tension adjusting device 10 provided on the arm 4 at a position in the middle of the upper thread supply path from a thread supply source (not shown) to the needle 7 via the thread take-up lever 8 will be described.

As shown in Figures 1 and 2, the suture tension adjustment device 10 has: a suture tension adjustment mechanism 11 provided on the front frame 4a of the arm 4; a suture provided on the rear frame 4b of the arm 4 The tension adjusting solenoid 12 ; and the pressing force transmission member 13 that transmits the driving force of the suture tension adjusting solenoid 12 to the pressing side clamping plate 22 of the pair of clamping plates 22 , 23 , and the like.

First, the thread tension adjusting mechanism 11 will be described. As shown in FIG. 2, the support frame 4c is integrally formed laterally with the front frame 4a and the rear frame 4b. Inside the supporting frame 4c, a small-diameter hole 4d is formed at approximately the front half to allow an intermediate rod (corresponding to the second transmission member) to be described later to slide in the front-rear direction, and at approximately the rear half. On the top, a large-diameter hole portion 4f having a diameter larger than the small-diameter hole portion 4d and continuing to the small-diameter hole portion 4d through an inclined step portion 4e is formed.

As shown in Fig. 2 and Fig. 3, a cylindrical fixing hole 4g facing forward is formed on the front frame 4a, and in the fixing hole 4g, a cylindrical suture tension regulator is fixed by a fixing screw 17. Seat 16. Inside the thread tension adjusting seat 16, a cylindrical bearing hole 16a is formed at the rear side, and a spring receiving hole 16b continuous with the bearing hole 16a is formed at the front side.

As shown in FIG. 3 , the suture tension adjustment shaft 18 is a thread support shaft that connects a rear small-diameter shaft portion 18a, a large-diameter shaft portion 18b continuous with the small-diameter shaft portion 18a, and a continuous large-diameter shaft portion 18b. The portion 18c is integrally formed with the thread forming shaft portion 18d which is continuous with the clamp support shaft portion 18c and forms a male thread on the outer peripheral surface. The clamp support shaft portion 18c and the thread forming shaft portion 18d are axially formed with a notch 18e having a predetermined width at the center, and are divided into two parts in the radial direction. Furthermore, an insertion hole 18f for inserting a drive rod (corresponding to a first transmission member) described later is formed in the small-diameter shaft portion 18a and the large-diameter shaft portion 18b.

The suture tension adjustment shaft 18 is fixed to the suture tension adjustment base 16 by fixing small screws 19 by inserting its small-diameter shaft portion 18a into the bearing hole 16a of the suture tension adjustment base 16 (see FIG. 4 ). The thread take-up spring 20 composed of a coil spring has a thread hook portion 20a, and the engaging portion 20b is engaged in the engaging groove 18g of the large-diameter shaft portion 18b, and is housed in the spring receiving hole outside the large-diameter shaft portion 18b. 16b. On the clamp support shaft portion 18c of the suture tension adjustment shaft 18, a disc-shaped clamp pressing member 21 forming a pair of half-moon hole portions 21a is fitted, and simultaneously pushes through the shaft holes 22a, 23a. The side tension plate 22 and the pressed side tension plate 23 are fitted, and finally the fixing nut 24 is screwed to the thread forming shaft portion 18d. Thereby, the pressing-side clamping plate 22 and the pressed-side clamping plate 23 formed as a pair are positioned between the clamping-side clamping shaft portions 18c. The pushing side and pushed side tensioning plates 22, 23 are rotatable relative to the suture tension adjusting shaft 18 respectively through the shaft holes 22a, 23a.

A drive rod 25 having a predetermined length is inserted into the insertion hole 18f of the small-diameter shaft portion 18a and the large-diameter shaft portion 18b. catch.

Next, the suture tension adjusting solenoid 12 provided on the rear frame 4b will be described with reference to FIG. 2 . The thread tension adjusting solenoid 12 (corresponding to a driving actuator and a solenoid actuator) is composed of a general proportional solenoid that changes the thrust linearly according to the current value. When a driving voltage is supplied from a control device not shown, the suture tension adjusting solenoid 12 drives the output shaft 12a to advance forward at a predetermined distance, and pushes the output shaft 12a against each other according to the driving voltage (driving current). The pressing force of the press-side clamping plate 22 changes.

Inside the front end side portion of the output shaft 12a of the thread tension adjusting solenoid 12, a bolt hole 12b having a female thread is formed. The stroke adjustment bolt 27 (corresponding to a threaded member) is screwed into the bolt hole 12 b to connect, and the fixing nut 29 is screwed to the stroke adjustment bolt 27 via the washer 28 . By screwing the fixing nut 29, the stroke adjusting bolt 27 is fixed on the output shaft 12a. That is, the stroke adjustment bolt 27 is fixed to the output shaft 12a, and the protrusion amount L from the output shaft 12a can be adjusted. Furthermore, a ring-shaped packing material 30 is attached to the rear end portion of the large-diameter hole portion 4 f corresponding to the front end of the thread tension adjusting solenoid 12 .

In the figure, an intermediate rod 31 is arranged, and the intermediate rod 31 straddles the large-diameter hole 4f and the small-diameter hole 4d between the stroke adjustment bolt 27 and the drive rod 25, and has approximately the same shaft diameter as the small-diameter hole 4d. shaft diameter, and has a specified length. A pair of front and rear washers 32, 33 having a diameter approximately the same as the shaft diameter of the large-diameter hole 4f are embedded in the intermediate rod 31, and a compression coil spring is embedded in the intermediate rod 31 between the washers 32, 33. 34 (equivalent to the return spring). The rear end of the washer 33 on the rear side is positioned by an E-ring 35 fixedly connected to the middle rod 31 .

As a result, the front washer 32 is always in contact with the inclined step portion 4e from behind by the elastic force (energizing force) of the compression coil spring 34, the rear end of the intermediate rod 31 is in contact with the head 27a of the stroke adjustment bolt 27, and the middle The rod 31 and the output shaft 12a move backward integrally until the washer 28 comes into contact with the gasket 30 and stops at the non-actuating position (see FIG. 2 ). At this time, only the front end of the intermediate rod 31 abuts against the rear end of the driving rod 25, and the position of the driving rod 25 relative to the suture tension adjusting shaft 18 remains unchanged. In addition, the pressing force transmission member 13 is constituted by these drive rods 25, the intermediate rod 31, and the like.

In the figure, since the thread tension adjusting solenoid 12 is fixedly connected to the rear side of the rear frame 4b, the part of the thread tension adjusting solenoid 12 protruding more rearward than the rear frame 4b is made of synthetic resin. Covered by the protective cover 38. A circular notch hole 38a for checking the operating state of the output shaft 12a of the thread tension adjusting solenoid 12 is formed at the center of the rear end surface of the protective cover 38 .

Next, the operation of the thread tension adjusting device 10 configured in this way will be described. When the suture tension adjusting solenoid 12 is not driven, as mentioned above, the elastic force of the compression coil spring 34 is used to make the intermediate lever 31 and the output shaft 12a together in the non-action position shown in FIG. 2 . At this time, since the contact between the rear end of the drive rod 25 and the front end of the intermediate rod 31 is released, the drive rod 25 is in a free state. As a result, the pushed side clamping plate 23 is not subjected to any pushing force from the pushing side clamping plate 22, and the two clamping plates 22, 23 are in a free state, so the upper thread between the two clamping plates 22, 23 is not affected. 9 does not impart tension. That is, the tension is zero.

On the other hand, when the driving voltage is supplied to the suture tension regulating solenoid 12, as shown in FIG. The pressed intermediate rod 31 also moves forward at the same time, abuts against the rear end of the driving rod 25, and pushes the driving rod 25 forward. As a result, since the front end of the drive rod 25 presses the pressing portion 21b of the thread clamp pressing member 21, the pressing side clamp 22 that has received the pressing force from the thread clamp pressing member 21 is The pressed side clamping plate 23 is pressed. As a result, tension is applied to the upper thread 9 in the middle through the two thread clamps 22 and 23 .

At this time, as the driving voltage supplied to the suture tension adjusting solenoid 12 increases, the pushing force on the driving rod 25 increases, so the tension applied to the upper thread 9 by the two tension plates 22 and 23 increases. Here, when the magnitude of the tension corresponding to the magnitude of the driving voltage supplied to the suture tension regulating solenoid 12 is inconsistent with the predetermined set value, the fixing nut 29 can be loosened, and the stroke regulating bolt 27 can be turned to adjust its protrusion. Quantity L. Thereby, the suture including the distance deviation from the front frame 4a to the rear frame 4b, the length deviation of the driving rod 25 and the intermediate rod 31, and the length deviation of the output shaft 12a of the suture tension adjustment solenoid 12 can be adjusted. The stroke amount of the tension adjusting solenoid 12 is kept constant, which can improve the precision of the pushing force of the pushing side clamping plate 22 .

As described above, the thread tension adjusting device 10 includes: the thread tension adjusting shaft 18 provided on the front frame 4a of the arm portion 4; 23 and the pushing side clamping plate 22 that pushes from the side of the arm portion 4 to the pushed side clamping plate 23; The suture tension adjusting solenoid 12 used for the tension; Thus, when the driving force formed by the driving of the suture tension adjusting solenoid 12 is transmitted to the pressing side clamping plate 22 through the pressing force transmitting member 13, since the intermediate rod 31 constituting the rear end side portion is larger than the front end side. Part of the drive rod 25 is thick (large diameter), so no deflection will occur in the middle part of the pushing force transmission member 13, and the pushing force corresponding to the change in the driving force of the suture tension adjusting solenoid 12 can be accurately transmitted to Pushing the side clamping plate 22 can improve the responsiveness and precision of adjusting the tension.

Also, the pressing force transmission member 13 has the driving rod 25 constituting the front end side part, and the intermediate rod 31 having a diameter larger than the driving rod 25 and constituting the rear end side part. Compared with other occasions, it can be manufactured at low cost and easily.

Also, the suture tension adjusting solenoid 12 is arranged on the rear frame 4b on the opposite side to the front frame 4a provided with the suture tension adjusting shaft 18, and the supporting frame 4c is laterally connected to the rear frame 4b and the front frame 4b. The part frame 4a is integrally formed, and the middle rod 31 is accommodated and supported inside the supporting frame 4c. The head portion 27a of the stroke adjustment bolt 27 of the pipe 12 is only in contact with the intermediate rod 31, so that the replacement work can be simplified.

Moreover, not only the intermediate rod 31 of the pressing force transmission member 13 is accommodated and supported in the support frame 4c, but also the oil and dust supplied from the oil tank to various parts can be reliably prevented from adhering to the intermediate rod by the support frame 4c. 31, which can prevent the reduction of the driving force transmission of the intermediate rod 31.

In addition, a compression coil spring 34 is provided, and the compression coil spring 34 imparts an elastic force on the loose side of the suture tension adjustment to the output shaft 12a of the suture tension adjustment solenoid 12 and the intermediate rod 31. When the suture tension adjustment solenoid When the driving of the tube 12 is stopped, the output shaft 12a and the intermediate rod 31 can be moved back to the original suture tension adjustment and relaxation position by the elastic force of the compression coil spring 34, and the expensive suture tension adjustment solenoid 12 does not need to be used. The restoration type can realize the miniaturization and cost reduction of the suture tension adjusting solenoid 12 .

Again, the front end of the intermediate rod 31 abuts against the rear end of the drive rod 25. When the suture tension adjustment solenoid 12 is not driven, the abutment can be released by the elastic force of the compression coil spring 34. When the suture tension adjustment solenoid 12 is not driven, the abutment can be released. When the driving of the tube 12 is stopped, the driving rod 25 does not move back, and only the output shaft 12a and the intermediate rod 31 are moved back to the original suture tension adjustment loosening position by using the compression coil spring 34, and the driving rod 25 is returned at the same time In comparison, the compression coil spring 34 can use a variety with weak elastic force and low cost.

In addition, even if the axis centers of the two rods 25, 31 are misaligned with each other due to manufacturing errors and installation errors of the two rods 25, 31, the driving rod 25 and the intermediate rod 31 are also in abutting relationship, and at the same time, because the intermediate rod 31 is relatively larger than the driving rod. 25 thick, it can reliably eliminate its dislocation absorption and ensure that the transmission performance of the driving force will not be reduced.

Moreover, between the front end of the driving rod 25 and the pressing side clamping plate 22, a clamping plate pressing member 21 is arranged, even if the clamping plate pressing member 21 is worn by the driving rod 25, the pairing of the driving rod 25 can be eliminated. The wearing and tearing of pushing side clamping plate 22, so needn't exchange expensive pushing side clamping plate 22, and only need to exchange low cost clamping plate pushing member 21 and get final product, can reduce maintenance cost. In addition, the length of the driving rod 25 can be shortened by the thickness of the clamp pressing member 21, and the rigidity of the driving rod 25 against bending can be further increased.

Also, the output shaft 12a of the suture tension adjusting solenoid 12 has a stroke adjusting bolt 27 that can adjust the length of the output shaft 12a in the axial direction by screwing, and by adjusting the screwing amount of the stroke adjusting bolt 27, the The stroke of the output shaft 12a of the suture tension regulating solenoid 12 is kept constant, which can improve the precision of the thread tension.

Also, a protective cover 38 is provided to protect the portion of the suture tension adjusting solenoid 12 that protrudes outward from the rear frame 4b, and on this protective cover 38, a confirmation thread tension adjusting solenoid is formed. The notched hole 38a for the operating state of the suture tension adjusting solenoid 12 can be reliably identified through the notched hole 38a through which the operating state of the suture tension adjusting solenoid 12 is visually confirmed or felt by fingers.

(change form)

Modifications of the above-mentioned embodiment will be described below.

1] The stroke adjustment bolt 27 and the intermediate rod 31 may be integrally formed and connected to the output shaft 12a of the suture tension adjustment solenoid 12 .

2] The pressing force transmission member 13 may also be constituted by using an integral member in which the intermediate rod 31 and the driving rod 25 are integrally formed.

3] The stroke adjustment bolt 27 may be omitted, and the installation position of the thread tension adjustment solenoid 12 with respect to the rear frame 4b may be finely adjusted in the front-rear direction.

4] As shown in Figure 5, the clamping plate pushing member 21 may not be provided, and the shape of the pressing side clamping plate 22 is made into the shape of Japanese Patent Publication No. 56-6314, and the driving rod 25 is directly opposite to the pushing side. The clamping plate 22 pushes.

5] The present invention is not limited to the embodiments described above, as long as it is an industry person, within the scope of not departing from the gist of the present invention, various changes can be added to the above-mentioned embodiments for implementation, and the present invention also includes these modified forms .

6] Of course, the present invention can be applied to the thread tension adjusting device of various sewing machines that apply tension to the upper thread in the middle of the upper thread path from the thread supply source of the sewing machine arm to the sewing needle via the thread take-up lever.

Claims (6)

1. A sewing thread tension adjusting device for a sewing machine, which applies tension to the upper thread in the middle of the thread supply path from the thread supply source of the sewing machine arm composed of the front frame and the rear frame to the needle through the thread take-up lever , characterized by including: A thread tension adjustment shaft provided on the front frame in the sewing machine arm; a pressed side tensioning plate supported by the thread tension adjustment shaft, and a pushing side tensioning plate that presses the pressed side tensioning plate from the side of the sewing machine arm; A driving actuator for changing the magnitude of the tension applied to the upper thread through the pressed side and the pushing side tension plate; and It has a first transmission member constituting a front end portion inserted through the inside of the suture tension adjustment shaft, and a second transmission member constituting a rear end portion connected to the drive actuator and thicker than the first transmission member. member, a pushing force transmitting member that transmits the driving force of the driving actuator to the pressing side clamping plate, The driving actuator is provided on the rear frame on the opposite side to the front frame on which the suture tension adjustment shaft is disposed, A support frame is integrally formed laterally with the rear frame and the front frame, and the second transmission member is supported within the support frame. 2. The sewing thread tension adjusting device for a sewing machine according to claim 1, wherein the driving actuator is constituted by a solenoid actuator, and a reset spring is provided on the second transmission member, The return spring applies an elastic force on the side for adjusting the tension of the thread to the output shaft of the solenoid actuator and the second transmission member. 3. The thread tension adjusting device for a sewing machine according to claim 2, wherein the front end of the second transmission member abuts against the rear end of the first transmission member, and when the driving actuator is not driven, , the abutment can be released by the elastic force of the reset spring. 4. The thread tension adjusting device for a sewing machine according to claim 2 or 3, wherein a thread tensioning plate is arranged between the front end of the first transmission member and the pressing side tensioning plate. Push components. 5. The thread tension adjusting device of sewing machine as claimed in claim 2 or 3, characterized in that, the output shaft of the solenoid actuator has a length in the axial direction of the output shaft that can be adjusted by screwing. Threaded member. 6. The sewing thread tension adjusting device for a sewing machine according to claim 1, wherein a protective cover is provided to protect the part of the driving actuator protruding to the outside of the rear frame, in which The protective cover is formed with a notch hole for checking the operating state of the drive actuator.

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