JPH0157595B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a needle bar mounting frame fixing device for fixing a needle bar mounting frame so that accurate straight stitches can be obtained when performing straight stitches with a zigzag sewing machine.

A zigzag sewing machine has a needle bar attached to a needle bar mounting frame that is swung by a control mechanism. When straight stitching is performed with such a zigzag sewing machine, the needle bar mounting frame swings slightly due to the play in each connecting part of the interlocking mechanism that interlocks the needle bar mounting frame and the control mechanism, making it difficult to perform accurate straight stitches. I had a problem with my eyesight.

In order to solve this problem, a protrusion is provided on the side of the connecting rod that interlocks the needle bar mounting frame and the control mechanism, and during straight stitching, this protrusion is sandwiched between two pronged locking pieces. There is a known sewing machine in which the connecting rod is fixed so that it does not move. However, in this known sewing machine, the continuous rod is fixed during straight stitching, but the needle bar mounting frame is not, so the needle bar may become loose due to play in the connection between the continuous rod and the needle bar mounting frame. As such, it is unstable.

The present invention aims to solve the problems of the conventional zigzag sewing machine as described above, and is designed to perform straight stitches by directly fixing the needle bar mounting frame.

That is, this invention uses an appropriate control mechanism to
In a zigzag sewing machine having a selection mechanism configured to be able to switch between performing zigzag stitches by swinging the needle bar mounting frame left and right and performing straight stitches by keeping the needle bar mounting frame stationary, the needle bar A lock pin that moves forward and backward in the direction of the needle bar mounting frame is provided on a fixed part of the sewing machine to which the mounting frame is attached, and the lock pin can be engaged with the needle bar mounting frame when the mounting frame is in a straight sewing position. A lock hole is provided, and an interlocking mechanism is provided that interlocks the lock pin so that when the control mechanism selects straight stitching by operating the selection device, the lock pin engages with the lock hole of the needle bar mounting frame, and the sewing machine arm When the operating selection dial of the zigzag pattern selection device provided in a predetermined part of To provide a needle bar mounting frame fixing device that can perform straight line stitching as accurately as a sewing machine.

The details of this invention will be explained below based on an embodiment shown in the attached drawings.

In FIG. 1, 1 is a sewing machine arm, 2 is a needle bar mounting frame, and this frame 2 is attached to a frame 3 within the arm 1 so as to be swingable at its upper end via a shaft 4. Reference numeral 5 denotes a connecting rod connected to the needle bar mounting frame 2, and this connecting rod 5 is moved by a known control mechanism (not shown) to swing the mounting frame 2 left and right.

A needle bar 6 is attached to the needle bar mounting frame 2 so as to be movable up and down. This needle bar 6 is raised and lowered by a known crank mechanism at the tip of an upper shaft (not shown).

Reference numeral 7 in FIGS. 1 and 2 is a mounting plate fixed to the front part of the frame 3 by means such as screws, and a part of the vertical lever 8 is rotatably mounted on this plate 7 by a shaft 9. A lock pin 10 is slidably fitted into a horizontal hole 11 in the lower part of the arm 1, and an engagement pin 12 provided on one side of the lock pin 10 engages with a notch 13 formed in the lower end of the lever 8.

A lock hole 14 is provided at one side of the lower end of the needle bar mounting frame 2, with which the lock pin 10 engages when the frame 2 is at the baseline position for straight stitching.

Reference numeral 15 in FIGS. 2 to 4 indicates a lever disposed on the side of the lever 8, and its lower end is rotatably attached to the mounting plate 7 via a shaft 16. Further, the upper ends of the levers 8 and 15 have shafts 1 in front and behind the movable frame 17.
8 and 19, and a pair of front and rear engaging pieces 20 are provided laterally at the upper end of the moving frame 17.

25 in Figure 1 is a mounting frame fixed to arm 1,
The vertical shaft 21 is rotatably attached to this mounting frame 25,
The right end of the swing piece 23 is fixed to the lower end of the vertical shaft 21, and the downward pin 24 at the left end of the swing piece 23 is fitted between the pair of engaging pieces 20 of the moving frame 17.

Further, a part of the swinging piece 26 is fixed to the upper end of the vertical shaft 21. This swing piece 26 has a pin 27 fixed on its left end and a locking piece 2 on the right end of the mounting frame 25.
Both ends of the tension spring 29 are locked in the holes 8. The center line a of this tension spring 29 passes through the center of the shaft 21 when the swing piece 26 is in the neutral position as shown in FIG. It acts to rotate the swinging piece 26 forward or backward beyond the range. Further, a two-pronged piece 30 is provided at the rear end of the swinging piece 26, and an engagement piece 31 of the mounting frame 25 is fitted into the two-pronged piece 30 to limit the range of forward and backward rotation of the swinging piece 26.

The left end of a connecting rod 33 is rotatably connected to the end of a piece 32 provided at the front of the swinging piece 26 by a shaft 34,
At the right end of this connecting rod 33, the elongated hole 50 and the pin 5
1, the right end of the moving frame 35 is connected so as to be movable left and right within a certain range.The right end of the moving frame 35 is rotatably connected to the upper end of a cam lever 36 by a shaft 37, as shown in FIG.

The cam lever 36 has its lower end connected to the shaft 38 as shown in FIG.
It is swingably attached to arm 1 by lever 36.
The pin 39 provided on the rear side is connected to the cam groove 41 of the cam 40.
is engaged in. This cam 40 is the sewing machine arm 1
A plurality of notches 43 are provided on the outer periphery of the sewing machine arm 1, and a locking piece 44 made of a plate spring that engages and disengages from the notches 43 is provided on the sewing machine arm 1. In addition, the operation shaft 42
A selection dial (not shown) is provided at the front end.

A selection cam 5 is attached to the operating shaft 42 as shown in FIG.
2 is fixed, and the selection device 53 is operated by this cam 52.

As shown in FIGS. 6 to 8, this selection device 53 has a shaft 55 parallel to the operating shaft 42 attached to a support frame 54 fixed to the sewing machine arm 1, and is movable in the axial direction and swingable on this shaft 55. A selection arm 57 that is moved by the selection cam 52 has a follower 56 attached to the
It is designed to move by. This selection arm 57 is swingably attached to the support part of the arm 1 by a shaft 58, and the selection arm 57 and the selection element 59 are connected to each other via the shaft 58 by bringing the selection element 59 at the lower end of this shaft 58 into contact with the selection cam 52. They are configured to rotate together.

The cam follower 56 has a circumferential groove 60 on the outer periphery of its boss portion, and a pin 61 at the lower outer end of the selection arm 57 engages with this circumferential groove, and the selection arm 57 is swung by the cam 52. The follower 56 is then configured to move along the axis.

73 in FIGS. 6 to 8 is a control mechanism,
62 is the swinging box. The lower end of this rocking box is swingably supported by the shaft 55, and a pin 63 fixed to the rear side engages with a notch 64 at the upper end of the follower 56, causing the rocker to swing with the follower 56. Box 6
2 are configured to swing together.

A connecting pin 66 at the rear end of the connecting rod 5 is pivotally engaged with a guide groove 65 at the front of the swinging box 62, and a swing width adjusting rod whose upper end is rotatably connected to this pin 66 67 is connected to a swing width adjusting arm 68 as shown in FIG. The arm 68 is fixed to a cylindrical shaft rotatably fitted outside the operating shaft 42, and the position of the pin 66 is adjusted by rotating the cylindrical shaft.

Reference numeral 69 in FIGS. 6 and 7 is a camshaft, which is rotated by a gear 70 in conjunction with the upper shaft of the sewing machine. This camshaft 6
A zigzag cam 71 and a linear cam 72 are fixed to the cam 9, and the cam follower 56 selectively contacts the outside of either of the cams 71 and 72, but the zigzag cam 71 has irregularities on its outer periphery and follows this. child 56
When the linear cam 72 contacts, the follower 56 swings and the linear cam 72
Since the outer periphery is a perfect circle concentric with the camshaft 69, it does not swing even if the follower 56 comes into contact with it. Although the figure shows a case where there is only one zigzag cam 71, many zigzag cams are provided with a plurality of zigzag cams having different shapes of outer peripheries so that various zigzag patterns can be sewn. Also,
When the cam follower 56 moves, its tip is designed to escape from the cams 71 and 72 so as not to engage with them.

In addition, when the cam follower 56 is in direct contact with the cam 72, the guide groove 65 of the swing box 62 is arranged along an arc centered on the connecting axis between the needle bar mounting frame 2 and the connecting rod 5. If this is done, the needle bar attachment frame 2 will be at the baseline position for straight stitching when switching to straight stitching no matter where the connecting pin 66 is located.

The fixing device of the present invention has the above configuration, and the third
The figure shows a state in which the swinging piece 26 is in the neutral position, and at this time the lock pin 10 is in the position shown in FIGS. Due to the relationship with the cam groove 41 and the action of the tension spring 29, the position is as indicated by the chain line b or c in FIG.

That is, the state shown in FIG. 1 is a state in which the sewing machine performs zigzag stitches, and at this time, the swing piece 26 is in the fifth position.
This is the position indicated by the chain line b in the figure, and therefore the vertical shaft 21 and the swinging piece 23, which are integral with the swinging piece 26, are closer to the front, and the moving frame 17 is positioned forward, that is, to the right in Fig. 2. I'm letting you do it. Therefore, the levers 8 and 15 are also
The lever 8 is tilted forward as shown by the chain line in the figure, and the lock pin 10 at the lower end of the lever 8 is moved back and removed from the lock hole 14 of the needle bar mounting frame 2, so that the mounting frame 2 can swing freely.

At this time, the cam 40 is in the position shown in FIGS. 1 and 7, and the cam follower 56 is in the position of the zigzag cam 71 due to the selection cam 52, and is in contact with the cam 71 by the action of a spring (not shown). When the camshaft 69 rotates together with the cams 71 and 72 as the sewing machine operates, the follower 56 swings together with the swing box 62, and the connecting pin 66 at the end of the connecting rod 5 swings the swing box 62 as shown in FIG. When it is above the center of movement, the needle bar mounting frame 2 swings by the connecting rod 5, and zigzag stitching is performed.

Next, when the operating shaft 42 is slightly rotated in the direction of the arrow in FIGS. 1 and 6, the selector 59 and the selection arm 57 are slightly rotated in the direction of the arrow in FIG.
contact with. At this time, since the cam 40 also rotates, the notch 43 on the upper left side of the cam 40 engages with the locking piece 44, and the cam lever 36 tilts from the position shown in FIG. 1 to the position shown by the chain line. Therefore, the moving frame 35 moves to the left in FIG. 1, which pushes the connecting rod 33 and moves to the left, causing the swinging piece 26 to rotate in the direction of the chain line c in FIG.

When the swinging piece 26 rotates, the swinging piece 23 integrated with it
The locking pin 10 moves forward as the moving frame 17 moves backward and the levers 8 and 15 tilt backward. At this time, if the timing coincides with the switching operation of the selection dial on the operating shaft 42 and the needle bar mounting frame 2 is at the baseline position for straight stitching, the lock pin 10 will fit deeply into the lock hole 14 and fix the mounting frame 2. .

However, when the lock pin 10 moves forward as described above, if the lock hole 14 of the mounting frame 2 is not in the correct position, the lock pin 10 hits the surface of the mounting frame 2 and cannot move any further, and the rocking piece 26 cannot turn to the position indicated by the chain line c in Figure 5. However, the misalignment between the swing piece 26 and the cam lever 36 during this time is absorbed by the misalignment between the long hole 50 and the pin 51 at the connecting portion between the connecting rod 33 and the movable frame 35.

Since the tension spring 29 of the swinging piece 26 is on the side of the chain line c as shown in FIG. 1 beyond the neutral position, the swinging piece 26 is moved to the side shown in FIG. The locking pin 10 is placed in the locking hole 14 and fixes the mounting frame 2 at the position indicated by the chain line c.

In this invention, when the sewing machine is switched to straight stitch as described above, the lock pin attached to a fixed part such as the sewing machine arm engages with the lock hole in the needle bar mounting frame, so that the needle bar mounting frame is directly fixed to the sewing machine arm. It will be the same as it was. Therefore, in the case of straight stitches, the needle bar is stabilized to the same extent as a regular straight stitch sewing machine, and the sewing machine has the effect of allowing beautiful straight stitches to be performed. Further, in the case of the configuration shown in the drawing, the swinging piece 26 is always biased to one side by the action of the tension spring 29, regardless of the position.
Since the prongs 30 are pressed by the biasing action of the tension spring 29, it is possible to prevent noise from being generated due to rattling of the parts of the lock mechanism during operation of the sewing machine.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view showing the main parts of a sewing machine using the fixing device of the present invention, FIG. 2 is a partially cutaway side view of the same, FIG. The figure is an exploded perspective view of the main parts, Figure 5 is an enlarged plan view explaining the operation of the rocking piece, Figure 6 is a partially longitudinal front view of the cam selection mechanism, and Figure 7 is a partially cutaway plan view of the same. , FIG. 8 is an exploded perspective view. 1...Sewing machine arm, 2...Needle bar mounting frame, 10
... Lock pin, 14 ... Lock hole, 53 ... Selection device, 73 ... Control mechanism.

Claims (1)

[Claims] 1. Has a selection device configured to be able to switch between performing zigzag stitching by swinging the needle bar mounting frame left and right and performing straight stitching by keeping the needle bar mounting frame stationary, using an appropriate control mechanism. In a zigzag sewing machine, a locking pin that moves forward and backward in the direction of the needle bar mounting frame is provided on a fixed part of the sewing machine to which the needle bar mounting frame is attached, and when the needle bar mounting frame is in a straight sewing position, A lock hole that can be engaged with the lock pin is provided, and when the cam control mechanism selects straight stitching by operating the selection device, the lock pin is interlocked so that the lock pin engages with the lock hole of the needle bar mounting frame. A needle bar mounting frame fixing device with a mechanism.