JPS6130596B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sewing machine, and more particularly to a wide-width sewing device for an electronic sewing machine that controls the amount of needle bar swing based on an electronically stored stitch pattern signal. The position where the needle and the hook intersect, the so-called needle and hook intersection condition, is always optimal regardless of the needle position, ensuring that the thread loop is captured by the hook and eliminating sewing problems such as skipped stitches and thread breaks. This is intended to enable wide-width stitching.

As is well known, the stitches on a sewing machine are created when the hook at the tip of the hook intersects with the needle at an appropriate time and captures the thread loop formed by the upper thread when the needle rises from the bottom dead center. It is constructed by intertwining with the bobbin thread. Therefore, in order for the hook to capture the thread loop, needle and hook movement with optimal needle and hook crossing conditions is required, and in fact, in a straight stitch sewing machine where the needle and hook crossing conditions are constant, the needle and hook crossing conditions are set to the optimal needle and hook crossing conditions. ing.

However, in fixed hook type zigzag sewing machines in which the hook rotates in a fixed position, which has been commonly used due to various advantages, the needle position relative to the hook moves as the needle bar oscillates, so it does not work like a straight stitch sewing machine. It is impossible to always perform sewing under optimal needle and hook crossing conditions, and it is necessary to accept some unsuitable needle crossing conditions. Moreover, as the needle bar swing width increases, the size of the thread loop that should be captured by the hook becomes too small or too large, causing trouble in the hook's ability to capture the thread loop, resulting in sewing problems such as skipped stitches and thread breakage. There are things to do. For example, as shown in Fig. 3, a horizontal fully rotating hook type zigzag sewing machine, that is, a hook 13 (rotating counterclockwise) installed perpendicularly to a hook shaft 12 arranged vertically (perpendicular to the plane of the paper) is used. In a zigzag sewing machine equipped with needle 14
The position P of the hook 13a at the tip of the hook 13 at the needle bottom dead center when the middle base line M is the center position is the hook axis 1.
Assume that the rotation angle of the hook 13 is set to the right by α with respect to the straight line Y-Y connecting the two axes and the middle base line M. This means that the needle 14 rises from the bottom dead center and the hook 13 moves to α.
It is shown that the needle 14 and the hook 13a intersect at the middle base line M when the needle 14 is rotated by a certain amount.

Generally, the needle and hook crossing conditions at the middle base line M are set to be optimal. Here, the needle bar swing width is S ₁ , the rightmost position of the needle 14, the so-called right base line, is R, the leftmost position of the needle 14, the so-called left base line, is L, and the distance between the right base line R and the middle base line M and the middle If the rotation angle of the pot 13 between the base line M and the left base line L is β ₁ , then on the right base line R, the rotation angle of the pot 13 from point P is (α−β ₁ )°, which corresponds to β° ₁ . The amount of rise of the needle bar decreases accordingly, and the size of the thread loop becomes smaller than the appropriate state, making it impossible for the hook 13a to catch the thread loop, which may result in skipped stitches. In addition, on the left base line L, the rotation angle of the pot 13 from point P is (α+β ₁ )°, and β°
The amount of rise of the needle bar increases by an amount corresponding to ₁ , and the size of the thread ring increases accordingly, which may cause thread breakage due to twisting of the thread ring or the like.

The present invention was developed as a result of studies in view of the above-mentioned circumstances, and embodiments of the present invention will be described below with reference to the drawings.

1 is an upper shaft pivotably mounted above the sewing machine frame (not shown) so as to rotate counterclockwise; 2 is a lower shaft pivotably mounted below the sewing machine frame parallel to the upper shaft; 3;
4 is a sprocket fixed to the upper shaft 1 and lower shaft 2, respectively; 5 is a timing belt installed between these sprockets;
The side sprocket 4 is the same as the sprocket 3 on the upper shaft 1 side.
It rotates at a constant speed in the counterclockwise direction in conjunction with . 6
is a base plate whose base end is fitted to the lower shaft 2 and has a plurality of teeth 6a formed on the fan-shaped top surface, and 7 and 8 are intermediate pulleys that are adjustable and pivotally connected to the upper left and right end surfaces of the base plate. ,
These pulleys lightly contact the outside of the timing belt 5 from both sides, and are set so as to apply appropriate tension to the timing belt 5.

Reference numeral 9 denotes an electromagnetic drive device mounted on the sewing machine frame, which is a reversible motor in this embodiment, and is driven based on a stitch pattern signal electronically stored in a microcomputer built into the sewing machine. A gear 10 is fixed to the motor shaft 9a of the reversible motor 9 so as to mesh with the teeth 6a of the base plate 6. When the reversible motor 9 is driven and the gear 10 rotates, the base plate 6 moves left and right around the driven shaft 2. oscillate. 6b is a fan-shaped long groove formed through the base plate 6, and a stopper 11 installed in the sewing machine frame is fitted into the long groove. Even if the reversible motor 9 goes out of synch, the base plate 6 is regulated so as not to swing more than necessary.

Figure 4 is a plan view showing the relationship between the needle and the hook of a horizontal full-rotation hook type zigzag sewing machine, and 12 is linked to the lower shaft 2 (the interlocking mechanism is omitted) to make a full rotation in the counter-rotation direction at twice the speed. The hook shaft is arranged vertically on the sewing machine frame (perpendicular to the plane of the paper in the same figure) so as to move.
Reference numeral 3 indicates a part of the pot which is integrally arranged perpendicular to the pot axis, and 13a is a hook formed at the tip of the pot.

The present invention is constructed as described above, and its operation will be explained. Fig. 1 shows the relative position of the base plate 6 in the state of the left base line L, and the reversible motor 9 moves the stitches stored electronically. When driven based on the pattern signal, the base plate 6 rotates around the lower shaft 2 via the gear 10 and the teeth 6a of the base plate 6 to a position where the right end surface of the long groove 6b of the base plate 6 abuts the stopper 11. FIG. 2 shows the relative position of the base plate 6 in the state of the right base line R. In this state, the base plate 6 moves around the lower shaft 2 until the left end surface of the long groove 6b and the stopper 11 come into contact. Rotate.
In this way, the position of the needle 14 is changed from the left base line L to the right base line R.
, the base plate 6 rotates from the state shown in FIG. 1 to the state shown in FIG. Rotate clockwise by °. This δ° corresponds to 2δ° in the hook shaft 12, which is twice as fast as the lower shaft 2, and as a result, the rotational phase of the hook shaft 12 is delayed by 2δ° with respect to the main shaft 1 when the needle swings. It is possible to do this. By distributing this 2δ° to the left base line L side and the right base line R side, a
Hook 13a on the left base line L side as shown in Figure A
The position P ₁ of the hook _13a on the right base line R side as shown in FIG.
δ)°. Here, set the needle bar width.
S ₂ (S ₂ > S ₁ ), the rotation angle of the pot 13 between the left base line L and the middle base line M and between the middle base line M and the right base line R is β ₂ (β
₂ > β ₁ ), then on the left baseline L, the rotation angle of the pot 13 from point P ₁ is (α − δ + β ₂ ) degrees, and on the right baseline R, the rotation angle of the pot 13 from point P ₂ is (α + δ -β ₂ )°, and all rotation angles are approximately equal to α, and the needle and hook intersection conditions are set to be optimal not only at the middle base line M but also at the left base line L and right base line R. Ru.

As described above, the present invention provides an electronic sewing machine in which the needle bar swing width is controlled based on a stitch pattern signal electronically stored in a microcomputer built into the sewing machine. An electromagnetic drive device that drives a base plate provided with a member for applying tension to the timing belt mounted between the interlocking lower shaft, and in this embodiment, an intermediate pulley, based on the stitch pattern signal; The embodiment is characterized in that a reversible motor is used to oscillate the needle bar in synchronization with the oscillating movement of the needle bar, and the rotational phase of the shuttle shaft relative to the main shaft can be adjusted when the needle bar oscillates. Therefore, it is possible to always ensure the best needle and hook crossing conditions almost regardless of the needle position, and it is possible to sew a wide zigzag pattern with a considerably large needle width, making it practical. Moreover, the effect is extremely large.

[Brief explanation of the drawing]

FIGS. 1 and 2 are front views showing a part of a sewing machine equipped with the mechanism according to the present invention. FIG. 1 shows the state of each part when the left base line is set, and FIG. 2 shows the state of each part when the right base line is set. FIG. 3 is a plan view showing the needle and hook intersection conditions according to the conventional example, and FIG. 4 is a plan view showing the needle and hook intersection conditions according to the mechanism of the present invention.
Figure B shows the case of the right baseline. In the figure, 1 is an upper shaft, 2 is a lower shaft, 5 is a timing belt, 6 is a base plate, 7 and 8 are intermediate pulleys, 9 is an electric drive device, and 12 is a hook shaft.

Claims (1)

[Claims] 1. In an electronic sewing machine in which the needle bar swing width is controlled based on a stitch pattern signal electronically stored in a microcomputer built into the sewing machine, the upper shaft and the lower shaft linked to the hook shaft are A base plate provided with a member for applying tension to a timing belt mounted therebetween, and an electromagnetic drive device that is driven based on the stitch pattern signal, and the base plate is driven by the electromagnetic drive device. 1. A wide-width stitching device for a sewing machine, characterized in that the rotational phase of a lower shaft which is oscillated to integrally support the base plate is adjusted in synchronization with the oscillation movement of the needle bar.