JPH075576U - Tensioning device for boring cycle sewing machine - Google Patents

Abstract

(57) [Summary] [Purpose] To give resistance to the upper thread during bar-tacking and to stabilize the upper thread around the hook. [Construction] In a boring cycle sewing machine which repeats a boring sewing operation for each cycle according to a feed shape of a main cam 17, a thread guiding means 24 for guiding an unthreaded upper thread 2 is provided, and the main cam 17 or preset. In synchronization with the number of stitches, the thread guiding means 24 acts on the upper thread 2 during bar-tacking to apply tension to the upper thread 2.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a boring cycle sewing machine, and more particularly to a device for applying tension to the upper thread of a boring cycle sewing machine.

[0002]

[Prior art]

 2. Description of the Related Art Conventionally, there has been known a holing cycle sewing machine for sewing the edges of buttons, for example. FIG. 6 and FIG. 7 show a part of this holing cycle sewing machine. 6 and 7, reference numeral 1 denotes a sewing machine head, and 2 denotes an upper thread. The upper thread 2 is a pair of plate-like plates for sandwiching the upper thread 2 and applying a predetermined tension. Via the first thread tensioner 3 and the second thread tensioner 4 which are made up of the thread, the thread thread guide 5, the thread balance 6, the first thread guide 7, the second thread guide 8, the needle bar thread guide 9, and the needle hole 10a of the needle 10. The upper thread loop supplied from the vertically moving needle is captured by the needle tip and circulates around the bobbin case to engage with the lower thread to form a seam.

As shown in FIG. 8, the holed shape (seam) is composed of a parallel going portion 11, a first bar-tacking portion 12, a parallel return portion 13, and a second bar-tacking portion 14, and these stitches are The eyelets are formed in this order every cycle according to a main cam (not shown) that determines the feed shape.

[0004]

[Problems to be solved by the device]

 Here, when forming the parallel going portion 11 and the parallel returning portion 13, both the first thread tension 3 and the second thread tension 4 are generally effective in order to increase the tension of the needle thread 2. As a result, the upper thread 2 is stretched to form a straight line, and the stretched upper thread 2 is sewn in such a manner that unillustrated lower threads are alternately wound. On the other hand, the first bar-tacking portion 12 and the second bar-tacking portion 14 are of the normal lock stitch method in which the knot portion between the upper thread 2 and the lower thread is in the cloth. Therefore, when sewing shifts from the parallel going part 11 and the parallel returning part 13 to the first bar-tacking part 12 and the second bar-tacking part 14, the dish-shaped plate of the first thread tension member 3 is lifted and the needle thread 2 The tension is weakened.

With the tension of the needle thread 2 weakened, the first bar-tacking portion 12 and the second bar-tacking portion 14 having a sewing width approximately twice the sewing width of the parallel going portion 11 and the parallel returning portion 13 are provided. When the sewing is performed, the needle thread 2 is rapidly consumed immediately after the sewing is transferred to the first bar-tacking portion 12 and the second bar-tacking portion 14, and the rotation of the hook causes the needle thread 2 to pass from the balance 6 through the needle hole 10a. There is a problem that the upper thread 2 coming over is too slack in the hook and the circumference of the upper thread 2 is not stable. Especially in the case of the Tetoron filament type thread with low resistance, the thread is not tightly tightened or the hook thread comes out of the hook. The thread is caught in the member on the back side of the shuttle and breaks.

[0006] Therefore, an object of the present invention is to provide a boring cycle sewing machine in which the needle thread around the shuttle is stabilized.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the tensioning device for a boring cycle sewing machine of the present invention provides a needle thread to be fed out in a boring cycle sewing machine that repeats a boring sewing operation every cycle according to the feed shape of the main cam. A thread guide means for guiding the upper thread, and in synchronization with the main cam or a preset number of stitches, the thread guide means acts on the upper thread at the time of bar-tacking to apply tension to the upper thread. I am trying.

[0008]

[Action]

 According to the tension applying device of the boring cycle sewing machine, the thread guiding means for guiding the upper thread causes the thread guiding means to act on the upper thread during bar tacking in synchronization with the main cam or the preset number of stitches. Then, by applying tension to the upper thread, resistance is applied to the upper thread, and abrupt delivery of the upper thread to the shuttle is suppressed.

[0009]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic perspective view of a main part of a tension applying device for a boring cycle sewing machine showing an embodiment of the present invention, FIG. 2 is a side view of the main part of FIG. 1, and FIG. 3 is an enlarged view around a main cam. The same parts as those described in the related art are designated by the same reference numerals, and the description thereof will be omitted. The point of difference between the boring cycle sewing machine of this embodiment and that of the prior art is that it guides the upper thread to be fed out and a movable thread guide as a thread plan internal means for changing the path of the upper thread in synchronization with the main cam. This is the point that a new section is provided. The movable yarn guide section will be described in more detail below.

In FIG. 1, reference numeral 15 indicates a vertical shaft that transmits the rotation of an unillustrated upper shaft at a reduced speed. A drive gear 16 is attached to the tip (lower end in the drawing) of the vertical shaft 15. There is. The drive gear 16 is meshed with the gear portion of the main cam 17 having a gear formed around it. Although not shown in the main cam 17 in order to avoid complication of the drawing, a cam groove for feeding in the direction of arrow A shown in FIG. 8 and a parallel head portion 11, a parallel return portion 13, A cam for controlling the sewing of the first bar-tacking portion 12 and the second bar-tacking portion 14 is provided. As shown in FIGS. 1 and 3, a circumferential side surface cam 18 is provided on the upper surface of the main cam 17, and a convex portion is provided at a position synchronized with the bar-tacking portion of the circumferential side surface cam 18. 28 is provided.

A lever 29 for rotatably supporting the roller 19 is arranged above the circumferential side cam 18 at its tip, and this lever 29 is rotated around a pin 20 fixed to a bed as a fulcrum. It is movably supported. One end of the first link 21 is rotatably supported at the other end of the lever 29, and the first link 21 is biased upward by a spring 31. One end of an L-shaped lever 22 is rotatably supported at the other end of the first link 21, and the L-shaped lever 22 is rotatably supported with a pin 23 fixed to a bed as a fulcrum. ing. At the other end of the L-shaped lever 22, one end of a second link 32 is rotatably supported, and at the other end of the second link 32, a movable yarn guide portion 24 is fixed. The movable thread guide portion 24 is formed with two slide holes 24b, 24b extending in the longitudinal direction, and these slide holes 24b, 24b are provided with step screws 25, 25 screwed to the sewing machine head. Are inserted loosely. That is, the movable yarn guide portion 24 is slidably supported by the step screws 25, 25 in the direction of arrow B shown in FIG. The tip end portion 24a of the movable yarn guide portion 24 is bent in an L shape so as to guide the upper yarn 2, and the tip end portion 24a is connected to the first yarn guide 7 as shown in FIGS. It is arranged between the second yarn guide 8.

Next, the operation of the tension applying device for the boring cycle sewing machine configured as described above will be described. First, as shown in FIG. 4A, the movable thread guide portion 24 is usually (when sewing the parallel going portion 11 and the parallel return portion 13), and the tip end portion 24a thereof has the first yarn guide 7 and the second yarn draft. The rollers 19 are arranged so as to be approximately on a line connecting the inner side 8 and the roller 19 and are placed on a flat surface portion on the circumferential side surface cam 18.

When the bar-tacking sewing is started, the roller 19 rests on the convex portion 28 on the circumferential side surface cam 18, and the lever 29 resists the biasing force of the spring 31 and rotates clockwise around the pin 20 as a fulcrum. The first link 21 moves downward (the direction of arrow C in FIG. 1). When the first link 21 moves downward, the L-shaped lever 22 rotates clockwise around the pin 23 as a fulcrum, and the second link 32 and the movable yarn guide portion 24 are moved as shown in FIG. 4 (b). Move to the right in the figure. Then, the needle thread 2 in the tip portion 24a is bent by the first thread guide 7 and the tip portion 24a, and the second thread guide 8 and the tip portion 24a as shown in the figure, and the resistance to the needle thread 2 is increased. Will be given.

When the bar tacking sewing is completed, the roller 19 descends from the convex portion 28 on the circumferential side surface cam 18 to the flat surface portion, and the movable thread guide portion 24 is moved to the original position shown in FIG. 4A. Will return to.

As described above, in the present embodiment, the path of the needle thread 2 is changed by the movable thread guide portion 24 in a direction in which the needle thread 2 bends when the bar tacking is performed in synchronization with the main cam 17, and the needle thread 2 is changed by this path change. Since the upper thread 2 is prevented from being suddenly fed out to the hook, it is possible to stabilize the upper thread 2 around the hook, and It is possible to prevent thread tightening failure and two upper thread breaks due to unwinding.

FIG. 5 is a top view of a movable thread guide portion in a tension applying device for a boring cycle sewing machine according to another embodiment of the present invention. The tension applying device of the boring cycle sewing machine of this embodiment is different from that of the previous embodiment in that a fixed thread guide portion 33 fixed to the sewing machine head side is newly provided.

Here, the tip portion 33a of the fixed yarn guide portion 33 is bent in an L shape in the opposite direction to the tip portion 24a of the movable yarn guide portion 24, and the tip portion 33a and The needle thread 2 is guided by a hole 34 formed by being surrounded by the tip portion 24a of the movable thread guide portion 24.

Therefore, when the bar-tacking sewing is started, the roller 19 is lifted up on the convex portion 28 on the circumferential side surface cam 18 as in the previous embodiment, and the movable thread guide portion 24 is moved to the arrow shown in FIG. Although it moves in the direction D shown, at this time, the diameter of the hole 34 becomes smaller (the passing hole area of the upper thread 2 becomes smaller), so that resistance is given to the upper thread 2 and the upper thread 2 moves to the hook. It has become possible to suppress the sudden expansion of.

Further, as another embodiment, resistance is given to the upper thread 2 at the time of bar-tacking between the balance 6 and the needle hole 10a in FIG. 1, so that the parallel going portion 11 and the parallel returning portion 13 are sewn together. It is also possible to use a thread tension which automatically floats the dish-shaped plate of the thread tension, and the point is that when the bar-tacking is performed, resistance is given to the upper thread 2 between the balance 6 and the needle hole 10a. Good Even with this structure, it is possible to obtain the same effect as that of the previous embodiment.

The invention made by the present inventor has been specifically described based on each embodiment, but the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say, for example, in each of the above embodiments, the movement of the movable yarn guide portion 24 is directly obtained from the main cam 17, but the operation timing (synchronization with the main cam 17). It is also possible to move the movable thread guide portion 24 as in the embodiment by using a sensor or the like and using a magnet or a cylinder. Further, a servomotor or an electromotor is used as a driving source of the boring cycle sewing machine. The sewing machine is designed to sew with a preset number of stitches, so when the bartacking is performed, the stitch count is read and synchronized with the stitch count. It is also possible to use a net or a cylinder to actuate the movable yarn guide portion 24.

[0021]

[Effect of device]

 As described above, according to the tension applying device of the boring cycle sewing machine of the present invention, it is provided with the thread guiding means for guiding the upper thread to be fed out, and is synchronized with the main cam or the preset number of stitches, at the time of bar-tacking, Since the thread guide means acts on the upper thread to apply tension to the upper thread, resistance is applied to the upper thread, and rapid feeding of the upper thread into the shuttle is suppressed. As a result, the upper thread is stabilized around the shuttle. In particular, even with a tetoron filament type thread, defective thread tightening, thread breakage, etc. are prevented.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of a main part of a tension applying device of a boring cycle sewing machine showing an embodiment of the present invention.

FIG. 2 is a side view of a main part of FIG.

FIG. 3 is an enlarged view around a main cam.

FIG. 4 is a view for explaining the operation of the device of the present invention.

FIG. 5 is a top view of a movable thread guide portion in a tension applying device for a boring cycle sewing machine according to another embodiment of the present invention.

FIG. 6 is a schematic perspective view of a main part of a boring cycle sewing machine showing a conventional technique.

7 is a side view of the main part of FIG.

FIG. 8 is a diagram for explaining a hole stitching shape.

[Explanation of symbols]

 2 needle thread 17 main cam 24 thread guide means

Claims (1)

[Scope of utility model registration request] 1. A boring cycle sewing machine that performs boring sewing operation repeatedly every cycle according to a feed shape of a main cam, including thread guiding means for guiding a needle thread to be fed, the main cam or a preset needle. A tension applying device for a boring cycle sewing machine, wherein the thread guiding means acts on the upper thread to apply a tension to the upper thread when bar-tacking in synchronization with the number.