JPH079277U - Sewing machine bobbin threading device - Google Patents

Abstract

(57) [Summary] [Purpose] After sewing with a sewing machine and cutting the upper thread, draw in the lower thread sufficiently to prevent the upper thread from remaining on the fabric surface. [Structure] The bobbin thread hoisting arm 32 is supported at the tip of a rotating arm 34 by a support shaft 36 so as to be swingable and urged toward a stopper pin 38 by a compression coil spring 40 to support the bobbin thread hoisting arm 32. After pulling a certain amount of bobbin thread, the counterbore adjustment cam 42
By pushing one end 32A of the bobbin thread hoisting arm 32 to increase the bobbin thread hopping amount by a set amount, the bobbin thread is sufficiently drawn in according to the elasticity of the bobbin thread, the weave density of the cloth, etc. To prevent the rest.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a bobbin thread threading device for preventing the upper thread from remaining on the fabric surface by striking the bobbin thread after the completion of sewing in a sewing machine such as a lockstitch boring machine.

[0002]

[Prior art]

 Conventionally, there is a sewing machine provided with a thread cutting mechanism as described in, for example, Japanese Patent Publication No. 56-6316.

As shown in FIG. 4 and FIG. 5, the thread trimming mechanism 1 is provided with a fixed knife 2 and a movable knife 3 which is swingable with respect to the fixed knife 2, and is used in the bobbin thread drawing device 4. By the thread passage portion 5A of the bobbin thread hoisting arm 5, the sewing thread is pulled near the tip of the fixed knife 2 and then the bobbin thread is cut by the fixed knife 2 and the moving knife 3.

Here, the bobbin thread hoisting arm 5 is screwed to a tip end of a rotating arm 7 which is swingably arranged by a support shaft 6. The driven arm 8 on which the moving knife 3 is formed is rotatably supported by a support shaft 9, and has a protruding shaft 10 at its tip end that engages with a cam hole 7A formed on the rotating arm 7 side. As shown in FIG. 5, when the rotating arm 7 and the bobbin thread drawing arm 5 are swung in the clockwise direction in the drawing, the driven arm 8 and the moving knife 3 are swung synchronously in the counterclockwise direction. The moving knife 3 cuts the bobbin thread after the bobbin thread portion 5A traces the bobbin thread to the vicinity of the fixed knife 2.

Here, as shown in FIG. 6, the upper thread is cut by the upper thread knife 12 while being drawn by the lower thread hoisting arm 5, but as shown in FIG. Since the lower thread 14 is entangled with the lower thread 14, the lower thread 14 is drawn by the lower thread hoisting arm 5, and the upper thread 13 left on the front side of the fabric 15 due to the generated tension is It is pulled into the back side of the fabric 15.

Reference numeral 16 in FIG. 4 is a slide plate for supporting the support shafts 6 and 9 and the fixed knife 2, and 17 is a needle plate attached to a cutout portion 18 of the slide plate 16. Has a needle hole 19 formed therein.

Further, reference numeral 20 in FIG. 4 is integrally attached to the lower thread hoisting arm 5, is a loop retainer for retaining a needle thread loop at a lower position of the needle 21, and 22 is attached to the sliding plate 16. The female grooves are shown respectively.

[0008]

[Problems to be solved by the device]

 In the thread cutting mechanism as described above, when the stretchability of the lower thread 14 is high or the density of the cloth 15 is high, the elongation of the lower thread 14 and the resistance of the cloth 15 are large. There is a problem in that the bobbin thread traversing operation is terminated while the bobbin thread 14 cannot be completely drawn into the back side of the fabric 15 only by the tension due to the rotation operation of 5. The upper thread remaining on the front side of the fabric is apt to cause thread fraying, which deteriorates the quality of the sewn product. This is because the operation stroke Y of the bobbin thread hoisting arm 5 is constant as shown in FIG.

On the other hand, as shown in FIG. 10, the total operating stroke L1 of the bobbin thread hoisting arm 5 is increased to L2, or as shown in FIG. 11, the operation of the bobbin thread hoisting arm 5 is performed. Means such as shifting the range by X may be considered.

However, in the former method, since the bobbin thread hoisting operation stroke within a certain period of time is increased as compared with the conventional method, when a fine count thread is used as the bobbin thread 14, the rotation speed of the thread path portion 5A increases. However, this causes a problem that the lower thread 14 is cut off while it is being traced. Further, in the latter method, since the mounting position of the bobbin thread hoisting arm 5 is changed, it is not possible to secure a space for a needle or a hook which is a mating component, which causes a problem such as interference.

The present invention has been made in view of the above-mentioned problems of the related art. Even when the stretchability of the bobbin thread is large or the cloth has a high weave density, the rotation speed of the yarn path part is increased. An object of the present invention is to provide a bobbin thread dragging device for a sewing machine capable of sufficiently bobbin threading without moving the bobbin thread hoisting arm or shifting the operating range of the bobbin thread hoisting arm.

[0012]

[Means for Solving the Problems]

 This invention is a sewing machine equipped with a thread cutting device that captures and cuts a lower thread after cutting an upper thread, and cuts the lower thread by the thread cutting apparatus when the lower thread is cut after sewing is finished. Prior to the procedure, the bobbin thread hoisting arm that pulls the bobbin thread in the direction in which the upper thread after cutting, which is entangled with the bobbin thread, is attached to the rotating arm that swings around the support shaft. In the device, the bobbin thread hoisting arm is swingably supported by a support shaft on a free end of the rotating arm, and the bobbin thread hoisting arm is restricted from rocking in a direction of decreasing the bobbin thread hoisting amount. A stopper pin that sets the initial swing position in the increasing direction, a spring that biases the bobbin thread pulling arm described above toward the stopper pin, and a swing end position in the bobbin thread pulling direction of the rotating arm. Immediately before, it abuts on the bobbin thread hoist arm, and Under thread drawing direction Te, along with swings against the spring, and the adjustment cam haul which are freely adjust the swing amount of its, by providing it is to achieve the above object.

[0013]

[Action and effect]

 In this invention, the bobbin thread for pulling the bobbin thread after cutting the upper thread is made swingable with respect to the rotating arm that supports the bobbin thread, and the bobbin thread bobbin arm has a normal amount. After bobbing the bobbin thread, depending on the setting value of the bobbin adjustment cam, the bobbin arm is further driven in the bobbin thread hopping direction with respect to the rotating arm to absorb the elongation of the bobbin thread or resist the resistance of the fabric. Then, the lower thread can be pulled completely to the back side of the fabric.

Further, since the amount of bobbin threading can be arbitrarily adjusted by the counterbore adjusting cam, the amount of bobbin threading can be optimally set according to the elasticity of the bobbin thread and the crease density of the fabric.

[0015]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, in a bobbin thread dragging device 30 according to an embodiment of the present invention, a bobbin thread dragging arm 32 is attached to a free end of a rotating arm 34 by a support shaft 36 so as to be swingable. While supporting the bobbin thread hoisting arm 32, the stopper pin 38 for restricting the rocking of the bobbin thread hoisting arm 32 in the direction of decreasing the bobbin thread hoisting amount and setting the rocking initial position in the increasing direction and the bobbin thread hoisting arm 32 are The compression coil spring 40 that urges in the direction of the stopper pin 38 faces the compression coil spring 40 of the bobbin thread winding arm 32 at the swing end position of the rotating arm 34 in the bobbin thread winding direction. Is located at a position immediately before the end of the swing of the rotating arm 34, and abuts on the bobbin thread winding arm 32, and rocks the bobbin thread winding arm 32 around the support shaft 36 in the bobbin thread winding direction against the compression coil spring 40. It can be moved and the amount of swing can be adjusted. The counterbore adjustment cam 42 is provided.

Since other configurations are the same as those in the conventional thread cutting mechanism shown in FIG. 4, the same parts are designated by the same reference numerals as in FIG. 4, and the description thereof will be omitted.

Here, the one end 32 A of the bobbin thread hoisting arm 32 moves from the supporting shaft 36 at the tip of the rotating arm 34 toward the supporting shaft 6 that is the swing center of the rotating arm 34. In the figure, the stopper pin 38 and the compression coil spring 40 are attached to the rotating arm 34 so as to extend along the upper surface and face both sides of one end 32A thereof.

The compression coil spring 40 urges one end 32 A of the bobbin thread hoisting arm 32 in a counterclockwise direction in the drawing and in a direction of pressing the stopper pin 38. The bobbin thread hoisting arm 32 is set so as to bob the bobbin thread by a normal amount at a position where one end 32A of the bobbin thread hoisting arm 32 is brought into contact with the stopper pin 38 by the compression coil spring 40.

Further, the counterbore adjusting cam 42 is provided with a slide groove 42A, and an adjusting screw 42B penetrating the slide groove 42A adjusts the longitudinal direction thereof, that is, the position in the direction of one end 32A of the bobbin thread hoisting arm 32. It can be fixed. In addition, a marking line 42C is formed along the slide groove 42A as a guide for the adjustment.

When the bobbin thread adjusting cam 42 is made to project a certain amount in the distal direction, the bobbin thread hoisting arm 32, which is swung in the clockwise direction in the figure together with the rotating arm 34, after the bobbin thread is threaded by a predetermined amount, (See FIG. 2), one end 32A is pushed further clockwise by the counterbore adjusting cam 42 against the compression coil spring 40 (see FIG. 3), and the bobbin thread is struck more than usual by the pushed amount. It is a thing.

Therefore, in this embodiment, by adjusting the protrusion amount of the counterbore adjustment cam 42 according to the elasticity of the lower thread and the texture density of the cloth, it is possible to adjust the amount that could not be conventionally trampled. In addition to the usual amount of bobbing, the bobbin thread is hooked so that the upper thread can be pulled completely to the back side of the fabric.

In the above embodiment, the compression coil spring 40 is configured to urge the one end 32A of the bobbin thread hoisting arm 32, but the present invention is not limited to this, and if necessary, Any means may be used as long as it biases the thread pulling arm 32 toward the stopper pin 38. Therefore, for example, a tension spring is stretched between the rotary arm 34 and the support shaft 36 of the bobbin thread hoisting arm 32 on the yarn path 5A side (preferably between the support shaft 36 and the thread path 5A). May be.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a lower thread threading device of a sewing machine according to the present invention.

FIG. 2 is a plan view showing the operation of the embodiment.

FIG. 3 is a plan view showing the operation of the same embodiment.

FIG. 4 is a plan view showing a thread cutting mechanism of a conventional sewing machine.

FIG. 5 is a plan view showing the operation of the thread cutting mechanism of the conventional sewing machine.

FIG. 6 is a cross-sectional view showing a state before needle thread cutting by a thread cutting mechanism of the conventional sewing machine.

FIG. 7 is a cross-sectional view showing a state during needle thread cutting by the thread cutting mechanism of the conventional sewing machine.

FIG. 8 is a sectional view showing a state in which the needle thread is cut and pulled by the thread cutting mechanism of the conventional sewing machine.

FIG. 9 is a sectional view showing an operating range of a bobbin thread hoisting arm by a thread cutting mechanism of the conventional sewing machine.

FIG. 10 is a cross-sectional view showing a state in which an operating range of a bobbin thread hoisting arm is increased in the conventional thread cutting mechanism.

FIG. 11 is a cross-sectional view in which the operating range of the bobbin thread hoisting arm in the conventional thread cutting mechanism is shifted.

[Explanation of symbols]

 30 ... Bobbin thread hoisting device 32 ... Bobbin thread hoisting arm 32A ... One end 34 ... Rotating arm 36 ... Support shaft 38 ... Stopper pin 40 ... Compression coil spring 42 ... Tapping adjusting cam 42B ... Adjusting screw

Claims (1)

[Scope of utility model registration request] 1. A sewing machine equipped with a thread cutting device for catching and cutting a lower thread after cutting an upper thread, and prior to a lower thread being cut and cut by the thread cutting apparatus when the lower thread is cut after sewing is completed. In the lower thread threading device of a sewing machine, a lower thread threading arm that draws the lower thread, which is intertwined with the upper thread in a direction to draw the upper thread, is attached to a rotating arm that swings around a support shaft. The bobbin thread hoisting arm is swingably supported by a support shaft at the free end of the rotating arm, and the bobbin thread hoisting arm is restricted from swinging in the direction of decreasing the bobbin thread hoisting amount and swings in the increasing direction. Stopper pin to set the initial position of movement,
A spring for urging the bobbin thread pulling arm in the direction of the stopper pin and an abutment position of the pivot arm in the bobbin thread pulling direction in the bobbin thread pulling direction are brought into contact with the bobbin thread pulling arm. A bobbin thread hoisting device for a sewing machine, characterized in that the bobbin thread hoisting device is swung in a bobbin thread hoisting direction around a support shaft against the spring and a hoisting adjustment cam whose swinging amount is adjustable is provided. .