JPS6025150B2 - Sewing machine needle thread supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a sewing machine that uses a thread take-up to pull up the needle thread to give a predetermined thread length to each stitch. The present invention relates to a needle thread feeding device for a sewing machine that continuously feeds out needle thread from a supply source via a feeding means such as a set of rollers that rotates in synchronization with the rotation of a main shaft.

Conventionally, this type of needle thread supply device has used a stepping motor to rotate a roller in synchronization with a main shaft, thereby letting out the needle thread.

However, the stepping motor requires accessory devices such as a pulse generator and a pulse motor drive circuit, which has the drawback of increasing the manufacturing cost of the device itself.

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

In FIG. 1, reference numeral 1 denotes a main shaft supported on a machine frame 2 so as to be rotatable about a viewing axis in conjunction with a drive source (not shown).
Connect the needles N' and move the needles N up and down. 3 is a thread take-up, which holds the needle thread T between the needle N and a bobbin winder (not shown) as a needle thread supply source.
It is linked to the main shaft 1 and moves up and down between two predetermined positions in synchronization with the up and down movement of the needle N so as to support and tension and relax the upper thread T.

4 is a worm gear fixed to the main shaft 1, 5 is a rotary shaft supported rotatably around a fixed axis obliquely inclined to the machine frame 2, and a gear 5A meshing with the worm gear 4 is fixed to the iron gear. This allows it to rotate in conjunction with the main shaft 1.

Reference numeral 6 denotes a conical pulley that is supported on the rotating shaft 5 so as to be movable only in all directions of the axis, but not rotated with respect to the rotating shaft 5, and between the pulley 6 and the gear 5A. There is interposed a spring S which always acts in a direction to separate the pulley 6 from the gear 5A. 7 is an electromagnetic magnet as an actuating means for moving the pulley 6 in the koji direction;
The tip of the drive shaft 7A contacts the front end surface of the pulley 6,
Due to the energization of the electromagnetic magnet 7, the booley 6 moves to the second position (position indicated by the chain line in FIG. 2) against the spring S, approaching the gear 5, and when de-energized, the booley 6 moves away from the gear 5A by the acting force of the spring S. Position (second design line position)
It is supposed to move to.

Reference numeral 8 denotes a trailing pulley, which is separated from the pulley 6 in the second position and moved along the inclined surface 6A of the pulley 6 while contacting the outer peripheral surface of the pulley 6 in the first position.
The drive shaft 9 is supported so as to be movable only in the ball direction on a driven shaft 9 which is rotatably supported, and rotates in conjunction with the rotation of the boley 6.

A moving means that moves and holds the driven pulley 8 in the axial direction of the driven shaft 9, and rotates with the rotation of the motor M and the motor M, and can also be rotated to the rock frame 2 along the driven pulley 9. The screw shaft 11 is rotated by the supported screw ball 11 and screw ratchet 11.
The engaging member 12 supports the driven pulley 8 so as to move thereon and engages with the driven pulley 8.

Although the position of the engaging member 12 on the screw shaft 11 is not shown, it can be detected by a detection means. 13 is a rotary roller fixedly supported on the driven shaft 9; 14 is a driven roller rotatably supported at the tip of an arm 14A whose base end is rotatably supported on the machine frame 2; The rotation roller 13 rotates as the rotation roller 13 rotates.

The rotating roller 13 and the driven roller 14 constitute an upper thread paying-out means '3A. Reference numeral 15 denotes an electromagnetic magnet fixed to the machine frame 2, and its drive shaft 15A is rotatably supported by the arm 14A. Excitation of the electromagnetic magnet 15 causes the driven roller 14 to rotate.

The rotating roller 13 is separated from the rotating roller 13 to release the gripping force on the upper thread T, and when de-energized, the rotating roller 13 comes into contact with the upper thread T to clamp the upper thread T. Next, the operation of this invention will be explained.

First, the electromagnet 15 is excited to separate the driven roller 14 from the rotating roller 13.

Then, take out the upper thread T from the upper thread T supply source, and
is locked between the driven roller 14 and the rotating roller 13,
Insert the tip of the needle thread T through the thread hole 3A of the thread take-up lever 3, and finally return the electromagnetic magnet i5 to the de-energized state, and prepare by stopping the needle thread several times with the driven roller 4 and rotating roller 13. Finish the threading work. Next, the fabric to be sewn (
(not shown) in the sewing machine sewing section, first, the electromagnetic magnet 7 is energized and the pulley 6 is pushed in the direction of the gear 5A against the elastic force of the spring S to set the pulley 6 to the second position.

Then, pulley 6 and driven pulley 8 no longer contact each other,
Transmission between the pulley 6 and the secondary pulley 8 is cut off, allowing the secondary pulley 8 to move in the axial direction. In this state, the motor M is driven to move the engagement member 12 and move the driven pulley 8 to a specific position on the slope around the pulley 6 in the first position {(
P+ is the position where the upper thread is unreeled, P is the feed pitch,
d is the cloth thickness)}. Next, when the electromagnetic magnet 7 is de-energized, the pulley 6 is set to the first position by the elastic force of the spring S, and the pulley 6 comes into contact with the subordinate scale pulley 8 at a specific position on the inclined surface. This is the amount of needle thread required for the stitches.

Then, ``When you start the sewing machine, main shaft 1 rotates.

The rotation of the main shaft 1 causes the needle N and the balance to move up and down, and is transmitted to the rotating shaft 5 via the worm gear 4 and gear 5A. The rotation of the rotating shaft 5 also rotates the pulley 6, and the driven pulley 8 that is in contact with the pulley 6 rotates clockwise. Since the driven roller 14 rotates, the rotating roller 13
The upper thread T, which is held between the driven roller 14 and the driven roller 14, is let out from the supply source to the thread take-up lever 3 side.

Then, the amount by which the upper thread T is paid out is paid out for each stitch at a rate of "P + phantom" (P is the feed pitch, d is the thickness of the cloth W) during one stroke of the thread take-up 3, and As shown in Fig. 4, the intertwined part ST of the upper thread T and lower thread LT is
, W, and a good "standard stitch" is formed. Further, when the driven pulley 8 is moved so as to come into contact with the pulley 6 at a portion where the diameter is the smallest, the amount that the driven pulley 8 rotates during one rotation of the pulley 6 becomes the smallest.

For this reason, the amount of rotation of the spreading roller 13 is also reduced, and therefore the amount of the needle thread T that is fed out is the smallest. Further, when the driven pulley 8 is moved so as to come into contact with the pulley 6 at the portion where the diameter is the largest, the amount that the driven pulley 8 rotates during one revolution of the pulley 6 becomes the largest. For this reason, the amount of rotation of the rotary roller 13 also increases, and therefore the amount of needle thread T that is fed out becomes the largest. Within this feeding amount range, the amount of needle thread that is fed out for "standard sewing" according to the pitch P and the fabric thickness d can be adjusted. This is what you set.

As described above, according to the present invention, by moving the contact position of the driven roller that moves with the upper thread letting-out means with respect to the pulley that is interlocked with the main shaft, the rotational speed of the driven roller per unit rotation of the main shaft is changed. However, the required amount of thread is paid out for each stitch of "standard stitching", so
Compared to a method in which the stepping motor is controlled to feed out the required amount of yarn, it does not require expensive accessory equipment, so it has the effect of significantly reducing manufacturing costs.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an apparatus according to an embodiment of the present invention, and FIG.
FIG. 3 is a side view of the needle thread feeding means, and FIG. 4 is a sectional view of the standard stitch J. 1...Main shaft, 6... ...Pulley, 8...
...Following fu. -Lee, 10... Transportation means, 13...
Upper thread feeding means. 1 spear and 3 drawings and 4 drawings

Claims (1)

[Scope of Claims] 1. A main shaft that is linked to a drive source and supported on a machine frame so as to be rotatable about a fixed axis, and a rotating shaft that is linked to the main shaft and supported on a machine frame so that it can be rotated about a fixed axis. , a pulley supported on a rotating shaft, and a driven shaft rotatably supported on the machine frame so as to be in contact with the pulley so as to rotate in conjunction with the rotation of the pulley, and to change the distance from the center of rotation of the pulley. A driven pulley supported so as to be movable only in the axial direction; a moving means for moving and holding the driven pulley in the direction of the driven shaft; The upper thread of the sewing machine is composed of a rotating roller supported on a driven shaft so as to be fed out, and a driven roller rotatably supported on the machine frame so as to rotate in contact with the rotating roller. Feeding device.