JPS6037105Y2 - Lower thread control device in sewing machine - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a bobbin thread control device for a sewing machine that prevents the bobbin thread from slipping out of the looper and gives an appropriate amount of slack to the bobbin thread.

Generally, the bobbin thread inserted into the guide hole at the tip of the looper at the start of sewing is held between the knife and a plate-shaped presser spring that is elastically attached to the underside of the knife's cutting edge immediately after it has not been cut by the knife. It has been done.

However, in the past, if for some reason the bobbin thread was not held between the pressing spring and the knife, or if the bobbin thread was not held sufficiently, the bobbin thread would not be able to guide the tip of the looper. For example, in order to perform double chainstitching, an inconvenient phenomenon often occurs, such as the thread falling out of the hole and being wrapped around the rotating shaft of a thread relaxing device that provides a predetermined amount of slack to the bobbin thread. Coupled with the fact that the rotating shaft of the device rotates at a high speed of 400 rpm, the amount of bobbin thread wrapped around this rotating shaft is extremely large, and it takes a lot of trouble to remove the wrapped bobbin thread one by one. There were defects in the sewing machine, such as the need for sewing, and the problem that it interfered with smooth sewing work.

Furthermore, if the bobbin thread is stretched for some reason and fed to the fabric while it is under tension, the fabric will be squeezed into a wavy shape, resulting in defects such as deterioration of the quality of the fabric. there were.

The present invention has been made to solve the above-mentioned defect. Even if the bobbin thread is not held between the pressing spring and the knife or is insufficient, the bobbin thread will still be able to guide the tip of the looper. You can avoid troublesome troubles caused by the thread slipping out of the hole and winding around the rotating shaft of the thread relaxing device, etc., and by giving the bobbin thread an appropriate amount of slack, even if the bobbin thread is (in a state of tension due to tension)
In an excellent sewing machine that can always obtain uniform and high quality fabric without causing the fabric to be squeezed into a wave shape by the bobbin thread when feeding the fabric, and also perform smooth sewing work. It is an object of the present invention to provide a bobbin thread control device.

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

1 is a machine base of the sewing machine, 2 is a throat plate, 3 is a sewing needle, 4 is a looper that can face the sewing needle, 5 is elastically pressed against a pair of fixed blade 5a and movable blade 5b by a pressing spring (not shown);
This is a knife that holds the bobbin thread inserted between the movable blade 5b and a presser spring (not shown), and all of the above are known.

Reference numeral 6 denotes a thread relaxation mechanism that provides a predetermined amount of relaxation to the bobbin thread in order to perform double chainstitching. An example of this thread relaxation mechanism 6 will be explained with reference to FIG. 2.

That is, this thread loosening mechanism 6 includes a bracket 1 which is attached to the front surface of the sewing machine base 1 with bolts 11, and a rotating shaft 10 that is rotatably driven from the main shaft 7 of the sewing machine via a belt 8 and a pulley 9.
2, and a thread relaxing cam 13, 13 for relaxing the bobbin thread is attached to the other end of the rotating shaft 10 by a fixing screw 14, and the cam surfaces 13a, 13 of the thread relaxing cam 13. 'a guides the bobbin thread 15, and the cam surface 13a
, 13'a, the amount of bobbin thread 15 necessary for double chainstitching can be appropriately relaxed and sent to the looper 4 in accordance with each back and forth movement of the looper 4. .

The bracket 12 has a mounting base 1 with a cutout window 16.
7 is attached, and a thread relaxing cam 1 is attached to this notch window 16.
3.13' is coming.

In addition, the tensioner 18 is fed out from a creel 45 which will be described later.
The bobbin thread 15 passes through the thread guide 19.20, passes between the presser plate 21 and the guide bar 22, faces the cam surfaces 13a and 13'a, and passes through the thread guide 23.
from there to the guide hole of the looper 4.

24 is a machine stand 1 between the looper 4 and the thread relaxing mechanism 6;
The lower thread control device 24 is fixed to a proper position of the bracket 28 with bolts 29 and 29 that fit into long holes 28a drilled in the bracket 28.
a thread gripping mechanism 25 that prevents the thread from coming off, a thread pulling mechanism 26 that pulls a predetermined amount of the bobbin thread 15 from the creel 45, and the thread gripping mechanism 25 and the thread pulling mechanism 26.
A driving source such as an air source or a hydraulic source (
(not shown).

The actuating mechanism 27 is driven by a driving source (such as the air source or hydraulic source).
a cylinder 29 into which air or oil is pumped from (not shown); and a piston rod 30 which is slidably fitted into the cylinder 29 and is given reciprocating motion by the air or oil which is pumped into the cylinder 29. Equipped with:

Air or oil is alternately supplied to air or oil supply portions 31 and 32 protruding from both upper and lower ends of the cylinder 29.

That is, when pushing down the piston rod 30, air or oil can be pumped from the supply section 31 on the upper end side, and when pushing the piston rod 30 up, air or oil can be pumped from the supply section 32 on the lower end side. .

Further, a collar piece 34 having a through hole (not shown) is bent at the upper end edge of the bracket 28, and a male threaded portion formed at the lower end of the cylinder 29 is inserted into this through hole (not shown). 33 and tightening with a nut 35, the cylinder 29 is attached to the bracket 28 at a predetermined angle.

A hook-shaped movable gripping portion 36 of the thread gripping mechanism 25 is loosely fitted in a suitable position in the middle of the piston rod 30, and the tip of this movable gripping portion 36 is bent to have a small roundness, and the tip is A cylindrical fixed grip portion 37 protruding from the bracket 28 is faced.

A threaded portion 38 is screwed into the lower end of the piston rod 30, and a pair of nuts 39, 39 are attached to this threaded portion 38.
are screwed together to prevent the movable grip portion 36 from coming off the piston rod 30.

A coil spring 40 is wound around the piston rod 30 between the lower end of the cylinder 29 and the movable grip 36, and the coil spring 40 always keeps the movable grip 36 between the movable grip 36 and the fixed grip. It is biased downward to enable contact pressure with 37.

That is, when the piston rod 30 is lowered, the movable grip part 36 and the fixed grip part 37 are maintained in a state of contact pressure,
The lower thread 15 interposed between these gripping parts 36 and 37 can be gripped, and when the piston rod 30 is raised, the movable gripping part 36 is pushed up by the nut 39 at the lower end of the piston rod 30, and the movable gripping part 36 is pushed up by the nut 39 at the lower end of the piston rod 30. portion 36 and fixed gripping portion 37 are maintained in a separated state, and both gripping portions 36.
The grip on the bobbin thread 15 interposed between the threads 37 and 37 can be released.

The thread shifting mechanism 26 includes a thread guiding tool 41 and a guide tube 42 that is integrally fixed to the bracket 28.

The upper end of the thread guiding tool 41 is clamped by nuts 39 and 39 that are screwed into the lower end of the piston rod 30, and the lower end is twisted at right angles in the direction of movement of the bobbin thread 15. A thread guiding hole 43 through which the bobbin thread 15 can be inserted is opened in this twisted portion.

A guide rod 44 is fixed to the midsection of the thread guiding tool 41, which is parallel to the piston rod 30 and can be slidably fitted into the guide tube 42.

Therefore, when the piston rod 30 is raised, the thread guiding tool 41 can face the contact pressure portions of both gripping portions 36 and 37 of the thread gripping mechanism 25 on the same horizontal plane S, as shown in FIG. At the same time, when the piston rod 30 descends, the bobbin thread 15 is let out from the creel 45 as shown in FIG. By loosening the thread, a sufficient amount of slack is provided so that the thread does not wind around the rotating shaft 10 of the thread relaxing mechanism 6, etc.

However, when performing double chainstitch work using a sewing machine, as shown in Figure 3, during sewing work, the bobbin thread is
5 is kept in a released state in which the thread gripping mechanism 25 is not operating, but when the double chainstitch operation is completed and the bobbin thread 15 is cut by the knife 5, at the same time the drive source (not shown) is Air or oil is forced into the cylinder 29 from its supply portion 31, and at the same time the piston rod 30 is lowered to the state shown in FIG. The bobbin thread 15 is securely held between the lower thread 15 and the lower thread 15.

Therefore, even if the bobbin thread is not held or is insufficiently held between the pressing spring (not shown) and the knife 5 immediately after the knife 5 cuts the bobbin thread 15,
The lower thread 15 is prevented from coming off from the looper 4, and as the lower thread 15 comes off from the looper 4, the lower thread 15 becomes extremely slack at the thread relaxing device 6, and the loosened lower thread 15 is This can prevent phenomena such as the yarn becoming entangled with the rotating shaft 10 of the yarn relaxing mechanism 6 that rotates at high speed or other members.

Further, as the piston rod 30 descends, the thread shifting mechanism 2
The thread guiding tool 41 of No. 6 also descends to give a predetermined amount of slack to the bobbin thread 15.
Since the bobbin thread 15 is held by the thread gripping mechanism 25, the amount of slack in the bobbin thread 15 due to the lowering of the thread guiding tool 41 is given by the creel 45 through the thread relaxing mechanism 6 with an appropriate amount of slack. Therefore, even if the bobbin thread 15 is to be sent to the fabric under tension, this tension will be alleviated, and the fabric will be prevented from being squeezed into a wavy shape due to the tension. .

When the sewing machine starts sewing again, air or oil is forced into the cylinder 29 from the supply section 32, and the piston rod 30 rises to return to its original state as shown in FIG. It returns and the same operation is repeated.

As described above, the bobbin thread control device of the sewing machine according to the present invention has the following features:
In a sewing machine equipped with a looper that can face the sewing needle and a thread relaxation mechanism that gives a predetermined amount of slack to the bobbin thread to perform double chainstitching, the machine is provided at an appropriate position on the machine between the looper and the thread relaxation mechanism, and the bobbin thread can be loosened as appropriate. a thread gripping mechanism that grips the thread to prevent the thread from coming off from the looper, a thread pulling mechanism that is provided near the thread gripping mechanism and pulls a predetermined amount of the bobbin thread from the creel, and the thread gripping mechanism and the thread pulling mechanism. Since it is equipped with an operating mechanism that is connected to the mechanism and connected to a drive source to operate them, even if the bobbin thread is not held between the pressing spring and the knife or is insufficient, Even if this happens, the troublesome trouble caused by the bobbin thread slipping out of the guide hole at the tip of the looper and winding around the high-speed rotating shaft of the thread relaxing device can be avoided, and the bobbin thread can Even when the bobbin thread is being fed to the fabric with an appropriate amount of slack, even if the bobbin thread is being stretched for some reason and is in a taut state, the fabric is always squeezed into a wave shape by the bobbin thread. To obtain a uniform and high-quality double chainstitched fabric without causing any damage, and to have an excellent effect in which sewing work can be carried out safely and smoothly.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is an overall schematic diagram of a sewing machine equipped with the device of the present invention, Fig. 2 is a perspective view of a thread relaxing mechanism associated with the device of the present invention, and Fig. 3 is an illustration of a sewing machine equipped with the device of the present invention. FIG. 4 is a perspective view before operation, and FIG. 4 is a perspective view after operation. 1... Sewing machine base, 3... Sewing needle, 4
...... Looper, 6... Thread relaxation mechanism, 1
5...Lower thread, 24...Lower thread control device,
25... Thread gripping mechanism, 26... Thread shifting mechanism, 27... Actuation mechanism, 29... Cylinder, 30... Zestone rod, 36...
・Movable gripping part, 37...Fixed gripping part, 41...
... Thread guide, 450@00 creel.

Claims (1)

[Scope of utility model registration request] In a sewing machine equipped with a looper that can face the sewing needle and a thread relaxation mechanism that gives a predetermined amount of slack to the bobbin thread to perform double chainstitching, the machine is provided at an appropriate position on the machine between the looper and the thread relaxation mechanism, and the bobbin thread can be loosened as appropriate. a thread gripping mechanism that grips the thread to prevent the thread from coming out of the looper, a thread pulling mechanism that is provided near the thread gripping mechanism and pulls a predetermined amount of the bobbin thread from the creel, and the thread gripping mechanism and the thread pulling mechanism. and an operating mechanism connected to a drive source for operating the lower thread control device.