JP2681919B2 - Sewing machine thread trimmer - Google Patents

Description

The present invention relates to a thread trimming device of a sewing machine, which cuts a sewing thread after sewing and holds a lower thread end after cutting. Used to. (Prior Art) As a prior art relating to the present invention, there is one described in JP-A-58-105791. In this prior art, in a thread trimming sewing machine in which a movable blade with respect to a fixed blade cuts a sewing thread in the forward movement in an upper space of a hook, a thread holding plate having elasticity is brought into contact with a thread holding plate, and a contact surface between the contact surfaces is abutted. The bobbin thread after thread cutting is held between the thread holding plate and the thread holding plate by elastically biasing the moving blade that moves forward and backward. (Problems to be Solved by the Invention) However, in the above-mentioned prior art, since the thread holding plate having elasticity is only brought into contact with the thread pressing plate, the moving blade of the both members is moved when returning. The bobbin thread that is cut when it is detached from the grip may be separated from both members before being sandwiched by the both members.Because no means for perfect contact is provided over the entire contact surface, there is a gap between the contact surfaces. Occurrence of a part may occur, and the bobbin thread may not be completely held even if it is held at the position. For this reason, when a highly elastic thread such as wooly nylon is used as the bobbin thread, the bobbin thread is contracted and drawn in after the thread cutting, and the next sewing cannot be performed as it is. Even with spun threads and cotton threads other than the above threads, when the upper thread is pulled up strongly by the balance action and the upper thread pulls the lower thread more than necessary onto the cloth, the lower thread should always be sewn at the start of sewing. Although the yarn must be strongly held, in the prior art, since the pressing surface is a plate material even if the yarn is pressed in, the yarn is slippery and has little holding force, which is unfriendly. In view of the above problems, the present invention, regardless of the type of bobbin thread,
It is a technical subject to surely hold the thread holding plate and the thread holding plate after cutting. [Structure of the Invention] (Means for Solving the Problems) Technical means taken for solving the above-mentioned technical problem is that at least one surface of the thread holding plate and the elastic thread holding plate facing each other is elastic. A member is joined, and an L-shaped arm is formed on the thread holding plate at the tip of the contact surface with the thread pressing plate to face the moving blade so that the thread holding plate and the thread holding plate come into contact with each other. The movable blade that moves back and forth on the surface is elastically urged and clamped, and the L-shaped arm of the thread holding plate is positioned on the sewing thread on the movable blade. (Operation) When the moving blade hooks the bobbin thread and enters between the thread holding plate and the thread pressing plate by the above technical means, the L-shaped arm of the thread holding plate is located above the bobbin thread. Then, the movable blade cooperates with the fixed blade to perform thread cutting, and then returns to the original state, but the cut bobbin thread end is interrupted by the L-shaped arm of the thread holding plate, so that the thread holding plate and the thread Since the elastic member is joined to the contact surface that remains between the presser plate and where the thread holding plate and the thread retainer plate come into contact, the bobbin thread is held firmly across the contact surface with good adhesion. can do. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 is a sewing machine bed, 2 is a lower shaft, 3 is a cauldron that rotates in the same manner as the lower shaft 2, 4 is a thread cutting drive arm, and a drive link 6 is rotatably connected to the thread cutting drive arm 4 with a screw 5. . 7 is a movable blade, which is fixed to a holder 8;
The holder 8 is supported on the lower shaft 2 via a bush 9, and one end of the holder 8 is loosely attached to the drive link 6 by a screw 10 (note that the bush 9 shown in the drawing is eccentric, but this eccentricity is the present invention. 11 is a fixed blade, which is located on the cauldron 3 and is fixed in place on the bed 1 by a screw 12, and 13 is its adjusting screw. Reference numeral 14 is a thread holding plate, and 15 is a thread holding plate having elasticity. Both members 14 and 15 are positioned between the cauldron 3 and the fixed blade 11 by a screw 16 and fixed to a proper position of the bed 1. Then, as can be seen from FIGS. 3 to 5, the thread holding plate
A downward L-shaped arm 15C having a width slightly smaller than the width of the through groove 7a of the movable blade 7 is formed at the tip of the one side portion 15a of the moving blade 7 (see FIG. 3). An elastic member 15b made of a rubber material is bonded to the surface facing to and by other method such as elastically abutting on the thread pressing plate 14, and the moving blade 7 moves back and forth between the contacting surfaces. To do. The thread cutting device of the present invention is configured as described above, and its operation will be described below. At the end of sewing, the movable blade 7 is moved from the state shown in FIG. 4 in the clockwise direction (indicated by the arrow) by the automatic driving means (not shown) which operates in synchronization with the needle bar movement, via the thread trimming drive arm 4, the drive link 6 and the holder 8. ) To. By this rotation, the moving blade 7 captures both the upper thread 16 and the lower thread 17 into the thread groove 7a (see FIGS. 3 to 5), and further the rotation proceeds, and the moving blade 7 moves the thread holding plate 15 L-shaped arm
While sliding the 15C into the through groove 7a, the thread holding plate 15 elastically contacts the thread holding plate 14 and enters between the contact surfaces of the elastic member 15b,
The upper and lower threads 16 and 17 are cut in cooperation with the fixed blade 11 (Fig. 6). Then, the movable blade 7 is rotated counterclockwise as shown in Fig. 7 to return to the original position. However, at this time, the cut end of the bobbin thread 17 is blocked by the L-shaped arm of the thread holding plate 15, and cannot be pulled out from the mating surface between the elastic member 15b of the thread holding plate 15 and the thread holding plate 14, and the elastic member 15b is It is sandwiched and held by elastic force. Without the holding action of this elastic member 15b, as described above, there is no reliable holding force, and it makes no sense when the upper thread pulls out the lower thread, and there is no adhesion on any holding surface. May not be retained. Also thread holding plate
Before the elastic member 15b of 15 and the thread pressing plate 14 pinch the lower thread 17 at the same time when the movable blade 7 returns,
It may come off more, and it may not be possible to reliably pinch it. Incidentally, in FIG. 8, an elastic member 14b is joined to the thread holding plate 14 instead of the thread holding plate 15. [Effects of the Invention] As described above, in the present invention, the bobbin thread used by contacting the thread holding plate with the elastic member joined to the thread pressing plate and forming the L-shaped arm for shielding the thread detachment is used. Regardless of the type, the cut end portion of the lower thread is reliably held between the thread pressing plate and the thread holding plate, and there is no inconvenience at the start of next-stage sewing. Therefore, the simple additional structure helps improve the efficiency of the sewing work.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of a sewing machine bed equipped with a thread cutting device of the present invention as seen from the hook direction, FIG. 2 is a view in the direction of arrow A of FIG. 1, and FIG. FIG. 4 is an exploded perspective view showing the operation of the device of the present application, and FIG. 8 is an external perspective view in which an elastic member is joined to the thread pressing plate. 1 …… Bed, 2 …… Lower shaft, 3 …… Cauldron, 4 …… Thread cutting drive arm, 6 …… Drive link, 7 …… Moving blade, 8 …… Holder, 11 ……
Fixed blade, 14 ... Thread retainer plate, 14b ... Elastic member joined to the thread retainer plate, 15 ... Thread holding plate, 15b ... Elastic member joined to the thread retainer plate, 15C ... Formed on the thread retainer plate L-shaped arm, 16 ……
Upper thread, 17 …… Lower thread.

Claims (1)

(57) [Claims] In a thread trimming sewing machine in which a movable blade with respect to a fixed blade cuts a sewing thread in its forward movement in an upper space of a hook, an elastic member is joined to at least one of opposing surfaces of a thread pressing plate and an elastic thread holding plate, The thread holding plate has an L-shaped arm directed downward toward the movable blade side at the end of the contact surface with the thread pressing plate, and moves forward and backward between the contact surfaces of the thread pressing plate and the thread holding plate. A thread trimming device of a sewing machine, which elastically urges and holds the moving movable blade, and an L-shaped arm of the thread holding plate is positioned on a sewing thread on the movable blade.