Needle plate assembly for sewing and the like machines

#Sewing machines can be used for hemming of collars, sleeves of various types of overcoats and knitted woolen garments as well as for other types of similar sewing or stitch forming operations. Such machines are generally compact and easy to operate, and these machines provide an efficient processing of knitted woolen and the like garments in the garment industry. However, traditional sewing machines are confined to use ordinary cotton thread, and it is difficult to use a special thread such as a woolen and the like threads. Moreover, the thread can easily break or can become tangled, and the big or hook needle might break during operation. The connection or securement of the threads is also frequently found to be difficult, resulting in the loss of thread which makes continuous operation of the machine difficult when the strips are separated by a given distance from one another. Thus, numerous problems can occur during the sewing or stitch forming operation.

#The above-mentioned difficulties are caused by the particular design of the known needle plate (see FIG. 2) which consequently has given rise to an improved type of needle plate, to which a column is attached at the lateral side next to the needle hole, while the lower edge has a flange fitted at the bottom (see FIG. 3), thereby to fix the thread firmly and to strengthen the respective thread connection. However, this improved type of needle plate has the following serious disadvantages:

#1. The design is of a fixed or stationary type. It is securely installed with a small clearance with reference to the upper direction of the disk needle or needles. When a woolen knitting strip of comparatively soft texture or of a fleecy nature is to be processed, the knitting strip will not only be damaged, but the needles may become deformed under the pressure and bend while continuing to swivel or oscillate. When handling products of a comparatively strong or heavier texture, the up and down swivel motion of the disk needle will provide more oscillations, and the needles can easily hook at or be blocked by the flange part, resulting in breaking and complete shut-down of the machine.

#FIG. 1 is a diagram relating a needle plate assembly and a sewing machine.

#FIG. 2 is a perspective view of a prior art needle plate.

#FIG. 3 is a perspective view of a further prior art needle plate.

#With reference to FIG. 4, there are provided a perforated needle plate 1, a fulcrum lever block 2, a thread staying or thread block 3, a coil spring 4, and associated assembly members.

#A compound needle hole 11 is provided in major portion of the needle plate 1. The needle hole 11 includes at the right or lateral wall a lateral concave thread guiding duct or recess 111, and at the left side the needle hole 11 extends in the shape of a semicircular or arcuate hole 112 from the horizontal base which is generally parallel to the bottom edge of the needle plate 1.

#There are a spring attachment hole 13 and a screw hole 14 at the upper terminus or minor attachment arm portion 12 of needle plate 1. With reference to FIG. 5A, the minor attachment arm 12 extends to the rear at an upper position of the needle plate 1, and it has an attachment hole 121 for securing the attachment part 12 at the respective sewing machine.