JPH0141400Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a mechanism for temporarily retracting an upper feed dog in a sewing machine having an upper feed mechanism.

[Prior Art] Conventionally, when performing reverse stitching during sewing work on a workpiece in this type of sewing machine, which is equipped with an upper feed dog that cooperates with a lower feed dog to feed the work cloth while nipping it, the reverse feed The back lever or the link connected thereto is operated by manually or by another drive device, such as a pneumatic cylinder or an electromagnetic solenoid, by reversing the upper feed adjustment device and converting the forward feed direction into the reverse feed direction. Ta.

Generally, in a normal lockstitch sewing machine that does not have an upper feed dog, the workpiece is fed only by the lower feed dog, so when sewing multiple layers of workpiece cloth, the feed dog should be set on the lower feed dog. Since only the fabric is fed, and the upper fabric has frictional resistance due to the presser foot, the upper fabric and the lower fabric are separated (commonly known as "scorching").

On the other hand, one feature of top-feed sewing machines is that they can use the top feed dog to set a slightly larger feed amount than the bottom feed dog to eliminate the above-mentioned "clog". be. At this time, another feature of this type of sewing machine is that if the upper feed amount is set larger, the upper fabric is fed more than the lower fabric, so that so-called "shirring" (gearing) can be performed.

That is, in any case, it was common to use the upper feed dog by a different amount from the lower feed dog.

[Problems to be solved by the invention] However, when performing reverse stitching as described above, in order to sew the part that has already been sewn immediately before, it is necessary to adjust the reverse feed amount of the lower feed dog and the reverse feed amount of the upper feed dog. If they did not match, there was a possibility that the difference between the two would cause the upper/lower feed dog to "misalign" and cause "wrinkles" or damage to the workpiece cloth.

In particular, with conventional sewing machines for the purpose of "gearthering," the reverse feed uses a mechanism that mechanically reverses the feed. Mechanically, it is extremely difficult to match the up/down feed amounts to the above, and in order to achieve this, it is necessary to fundamentally redesign the adjustment/reverse feed mechanism, resulting in a significant increase in cost.

That is, as a result, although high sewing quality can be obtained in normal feed by taking advantage of the characteristics of a top-feed sewing machine, there is a problem in that when reverse stitching, an undesirable phenomenon occurs in which the sewing quality deteriorates. It was hot.

Furthermore, when changing direction, such as corner stitching during normal feed, the upper feed dog protrudes below the presser foot, which obstructs changing the direction of the workpiece cloth or inserting and removing it.

The present invention has been developed by focusing on the problems of the conventional method as described above, and eliminates the above-mentioned drawbacks when backstitching is performed in the middle of sewing. The purpose of this invention is to provide an upper feed dog retraction mechanism that improves performance.

[Means for Solving the Problems] Therefore, in the present invention, the above object is achieved by configuring the upper feed dog to be temporarily raised/retracted during reverse feed of reverse stitching, etc. It is something to do.

[Function] With the above-mentioned configuration, when reverse stitching is performed, the sewing machine is reversely fed only by the lower feed dog, so the above-mentioned deterioration in sewing quality does not occur, and the number of stitches in reverse stitching is generally small. Therefore, problems such as "misalignment" between the upper and lower fabrics are less likely to occur. Furthermore, operability during corner stitching etc. is improved.

[Examples] The present invention will be described below based on Examples.
FIG. 1 is a side view of the main part of an embodiment of the main part of the upper feed dog retraction mechanism according to the present invention (shown with the cover removed),
FIG. 2 shows a front view of the main part of FIG. 1.

(Structure) In both figures, F is the frame of the head of the sewing machine, and C is the cover (face plate). Reference numeral 6 denotes an upper feed dog, which performs four predetermined movements, upward/downward and left/right, by means of the driver 5, the vertical rod 10, etc. Since this four-movement drive mechanism is well known, its explanation will be omitted.

11 is a presser foot, which is fixed to the presser bar 8.
1 is a rotary solenoid, and an output shaft 1a is rotatably disposed on a bracket 12 which is attached and fixed to a cover C with two machine screws. 1b is a detent pin. An operating arm 2 is fixed to the output shaft (rotary shaft) 1a of the rotary solenoid 1, and is pivotable around a horizontal step screw 9 on a support base 7 fixed to a presser bar 8. A bell-crank-shaped lever 3 (link device) is disposed at , and the upper end of the horizontal lever portion is configured to abut and engage with the lower surface of a pin 4 protruding from the upper and lower rods 10 .

(Operation) Next, the operation in the above configuration will be explained.
In the non-energized position where the rotary solenoid 1 is not energized, the actuating arm 2 fixed to the output shaft 1a
is in a position where no force is applied to the bell crank lever 3.

During reverse feed during reverse stitching, when the solenoid 1 is energized in conjunction with the reverse feed (back) lever or by a switch (not shown) independently provided elsewhere, the output shaft 1a moves in the direction of the arrow in Fig. 1. The bell crank lever 3 is rotated around the stepped screw 9 via the operating arm 2, and the pin 4 is pushed upward to raise the vertical rod 10, drive body 5, and upper feed dog 6 to a predetermined height. Since the work cloth is only fed by the lower feed dog, there is no risk of damaging the cloth.

Further, at this time, the lower surface of the upper feed dog is higher than the lower surface when the presser foot is raised, so that it does not get in the way when the work cloth is taken in and out or when the direction is changed (for example, when sewing corners).

Furthermore, in cases where, for example, a stepping motor or the like is connected to the upper feed drive for control, the present invention eliminates the need to reverse the upper feed mechanism, thereby preventing the stepping motor from being forced to reverse drive. It's very convenient.

(Other Examples) In the above example, a rotary solenoid was used as the drive source for retracting movement of the upper feed dog, but the drive source is not limited to this, and a linear solenoid or a linear actuator of an air cylinder may be used Of course, it may be used.

[Effects of the invention] As explained above using the embodiments, according to the invention, when reverse stitching is performed on a top feed sewing machine, reverse feed is performed only by the bottom feed dog, so there is no possibility of damaging the workpiece fabric or impairing the sewing quality. This eliminates the risk of deterioration, and improves operability when moving work cloth in and out and changing direction.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are a side view and a front view of a main part of an embodiment of the upper feed dog retraction mechanism according to the present invention, respectively. 1...Rotary solenoid (actuator),
1a... Output shaft, 2... Operating arm, 3... Lever (link device), 4... Pin, 5... Drive body,
6... Upper feed dog, 7... Support stand, 8... Presser bar,
9... Step screw (horizontal axis), 10... Vertical bar, 1
1... Presser foot.

Claims (1)

[Scope of Claim for Utility Model Registration] In a sewing machine equipped with an upper feed dog mechanism, a presser bar is supported vertically on a sewing machine frame and has a cloth presser foot at its lower end; a support base fixed to the presser bar; A lever rotatably supported on a support base, and a pin 4 that protrudes from the upper and lower rods for driving the upper feed dog and engages with the upper and lower rods to raise them when the lever rotates.
and an upper feed retraction mechanism consisting of an actuator that rotates a lever fixed on the sewing machine frame.