JPS6131754Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is an automatic thread in which the cut bobbin thread is held between the pressing spring and the movable blade by a pressing spring elastically attached to the lower surface of the movable blade. This relates to a cutting device.

Normally, in order to hold the bobbin thread by a plate-shaped pressing spring that is elastically attached to the lower surface of the cutting edge of the movable blade, it is necessary to provide this pressing spring with appropriate strength. In this case, it is conceivable to take into account the thickness of the bobbin thread, deterioration of the press spring over time, etc., and always adjust the strength of the press spring to be suitable for holding the bobbin thread.

As shown in FIG. 1, the spring pressure adjustment mechanism for the press spring provided in the automatic thread trimming device has conventionally been fixed to a part a of the machine base of the sewing machine with a fixing screw b and a lock nut e. Each press is c
The tips of adjustment screws d screwed into a part of the base of the sewing machine from below are exposed to the bottom side of the sewing machine, and by turning the knobs of these adjustment screws d, the pressing spring c is pushed up from below of the sewing machine, and the pressing spring c is pushed up. However, in this case, it is extremely difficult to operate the adjustment screw from below the sewing machine due to the unreasonable posture, and if necessary, many devices such as an automatic thread trimmer are used. This required troublesome work, such as having to remove the parts.

The present invention was devised to eliminate such drawbacks, and its purpose is to provide an automatic thread for sewing machines that can reliably adjust the strength of the pressing spring with extremely simple operation and without removing any parts of the sewing machine. The purpose is to provide a cutting device.

In order to achieve the above object, the present invention includes a fixed blade disposed below the throat plate on the bed side with respect to the sewing needle hoistway, and a fixed blade disposed below the fixed blade and between the throat plate and the looper. a sewing machine; An eccentric cam is provided at the other end of the main shaft having a rotation operation part toward the front side of the main shaft, and the peripheral surface of the eccentric cam is brought into contact with the lower surface of the pressing spring to rotate the rotation operation part. and a spring pressure adjustment mechanism that adjusts the pressing force of the pressing spring against the movable blade via the eccentric cam.

Hereinafter, one embodiment of the present invention will be specifically described based on the drawings.

1 is an arm of the sewing machine, 1' is a bed, 2 is a throat plate, 3 is a sewing needle, and 4 is a looper that can be opposed to the sewing needle 3, all of which are known.

Reference numeral 5 denotes a fixed blade disposed below the throat plate 2 on the bed 1' side with respect to the sewing needle hoistway.
Several (three in this embodiment) movable blades 6, ... are closely stacked on the lower side of the blade, and these fixed blades 5 and movable blades 6 constitute a pair of knives. There is.

The fixed blade 5 has a first slidable blade disposed below the bed 1' so as to be orthogonal to the sewing needle hoistway.
It is fixed to the tip of the slide plate 7 with screws 8, etc., and the tip has sharp blades 5a,...
have. Then, the first slide plate 7
As shown in FIG. 3, the slide plate 7 is biased toward the sewing needle hoistway by a spring 9, and the forward movement of the slide plate 7 is restricted by a stopper 10.

Further, a leaf spring-like pressing spring 11,... is elastically attached to the lower surface of the cutting edge of each movable blade 6,
This pressing spring 11 pushes up the movable blade 6 from below to the top, presses the movable blade 6 against the fixed blade 5, and
It has the role of receiving and holding the bobbin thread between the movable blade 6 and the pressing spring 11. Each of the pressing springs 11 is disposed on the upper surface of a contact plate 15 which is fixed to the lower surface of the first slide plate 7 together with the screw 8 for attaching the fixed blade 5.
It is fixed by 2,...

Further, the movable blades 6 are interposed between the fixed blade 5 and the pressing spring 11, and the movable blades 6
has first and second thread hooking parts 6 on one side edge of the leading end book.
a, 6b, and is fixed to the tip of the second slide plate 13, which is arranged so as to be able to slide parallel to the first slide plate 7, with screws 27, and the throat plate 2 It moves forward and backward between the looper 4 and the looper 4.

The second slide plate 13 is connected to a drive source (not shown) such as a rotary solenoid via a rotary lever 16 constituting a link mechanism, so that the movable blade 6 is moved forward and backward with a predetermined stroke. ing.

The pivot lever 16 is rotatably supported at its center by a screw-shaped pivot 17 on a bracket 20 fixed to the sewing machine bed 1' by bolts 21, and one end thereof is connected to the second slide. The rotary lever 16 is connected to the base end of the plate 13, and the rotary lever 16 is connected to the second slide plate 13 by providing a long hole 1 in the longitudinal direction of the rotary lever 16.
6a, a screw-shaped connecting pin 18 is provided protruding from the upper surface of the slide plate 13, and the connecting pin 18 is slidably fitted into the elongated hole 16a.

A long hole 16b in the longitudinal direction is also formed at the other end of the rotating lever 16, and is integrated with a link mechanism (not shown) connected to this long hole 16b from a drive source (not shown). The connecting pin 19 is fitted.

Further, the bracket 20 is provided with a guide groove 22 into which the first and second slide plates 7 and 13 are slidably fitted, and a cover plate 23 is inserted into the screw 24 from above the guide groove 22. , . . . to guide the upper surfaces of the slide plates 7, 13 and to prevent them from coming off.

In addition, as shown in FIG. 5, the contact plate 15 has
A stepped notch 25 is provided, and this notch 25
The eccentric cam 26 of the spring pressure adjustment mechanism 50 is arranged.

The spring pressure adjustment mechanism 50, as shown in FIG.
A main shaft 30 having a threaded portion on the outer circumferential surface, a rotating operation part 26a having a hexagonal depression formed at one end of the main shaft 30, and an eccentric cam 26 provided at the other end of the main shaft 30. Then, attach the threaded part of the main shaft to the plate 1.
By screwing into the main shaft 3 and fixing it with the lock nut 14, the rotary operation part 26a is disposed toward the front side of the sewing machine.
Pressing the circumferential surface of the eccentric cam 26 at the other end of the spring 11
It is placed in contact with the bottom surface of the By appropriately rotating the knob of the rotation operation part 26a from the front of the sewing machine, when the peripheral surface of the eccentric cam 26 having a longer radial distance comes into contact with the lower surface of the presser spring 11, the presser spring 11 is rotated. It is possible to increase the pressing force of the presser spring 11 against the movable blade 6 by being strongly pushed upward, and when the circumferential surface of the eccentric cam 26 having a shorter radial distance comes into contact with the lower surface of the presser spring 11, the presser foot Since the upward pushing force of the spring 11 is weakened, the pressing force of the pressing spring 11 against the movable blade can be reduced.

Furthermore, the fixed blade 5 is provided with a rectangular cutout window 5b as clearly shown in FIG. The attached portions, that is, the screws 27, ... are exposed upward, and the position of the fixed blade 6 can be adjusted, or installed or removed by loosening the screws 27 directly from above using a tool such as a wrench through the notched window 5b. ing.

What should be noted in the above configuration is the presser spring 1.
The spring pressure adjustment mechanism of No. 1 includes a rotary operation section 26a that faces the front of the sewing machine and has a knob at its tip for easy operation.
Since it is only necessary to rotate the eccentric cam 26 around the main shaft, the sewing worker can easily push the force of the spring 11 while sitting and use only a simple tool such as a wrench or spanner. It is possible to make adjustments and to securely hold the bobbin thread by imparting appropriate strength to the pressing spring 11 without having to take off parts of the sewing machine in an unreasonable posture.

As can be understood from the description of the embodiments above, the automatic thread trimming device of the sewing machine of the present invention includes a fixed blade disposed below the throat plate on the bed side with respect to the sewing needle hoistway;
A movable blade is placed below the fixed blade and moves forward and backward between the throat plate and the looper, and the movable blade presses the lower surface of the cutting edge of the movable blade to contact the lower surface of the fixed blade and moves the bobbin thread. An eccentric cam is provided at the other end of the main shaft, which has a presser spring that is received between the blade and holds the bobbin thread, and a rotating operation section facing the front side of the sewing machine, and the peripheral surface of the eccentric cam is attached to the presser spring. It is extremely simple because it is equipped with a spring pressure adjustment mechanism that adjusts the pressing force of the pressing spring against the movable blade via the eccentric cam by rotating the rotating operation part in contact with the lower surface of the spring. The construction allows for easy adjustment of the pressure spring strength from the front of the sewing machine without having to remove any parts of the sewing machine, and this operation can be done in a comfortable position while the sewing worker is seated. This has the advantage that a predetermined spring strength suitable for holding the bobbin thread can be obtained reliably and quickly.

[Brief explanation of the drawing]

Fig. 1 is a partially longitudinal front view showing a conventional example of the present invention, Figs. 2 to 6 show an embodiment of the present invention, and Fig. 2 is a general outline of a sewing machine equipped with the device of the present invention. FIG. 3 is a plan view, FIG. 4 is a front view partially cut away, FIG. 5 is a bottom view showing the main part of FIG. 3, and FIG. FIG. 1'... Bed, 2... Throat plate, 3... Sewing needle, 4
... Looper, 5 ... Fixed blade, 6 ... Movable blade, 1
1...Push it, 26...Eccentric cam, 26a...
Rotating operation unit, 30...Main shaft, 50...Spring pressure adjustment mechanism.

Claims (1)

[Scope of utility model registration request] A fixed blade disposed below the throat plate on the bed side with respect to the sewing needle hoistway, a movable blade disposed below the fixed blade and moved forward and backward between the throat plate and the looper, and A pressing spring presses the lower surface of the cutting edge of the blade to bring it into contact with the lower surface of the fixed blade, receives the bobbin thread between it and the movable blade, and holds the bobbin thread; An eccentric cam is provided at the other end of the main shaft, and the circumferential surface of the eccentric cam is brought into contact with the lower surface of the presser spring, and the rotary operation section is rotated to rotate the movable blade of the presser spring via the eccentric cam. An automatic thread trimming device for a sewing machine, characterized in that it is equipped with a spring pressure adjustment mechanism that adjusts the pressing force against the thread.