Sewing – Elements – Needles
Patent
1993-01-07
1995-02-28
Nerbun, Peter
Sewing
Elements
Needles
163 5, D05B 8500, B21G 102
Patent
active
053927257
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a sewing machine needle and a method for manufacturing the same.
BACKGROUND ART
Conventionally, manufacturing of a sewing machine needle has been carried out by a press operation such as die press operation or die pressing, flow press operation, or the like in place of metal cutting or machining. However, such a well-known press operation requires a combination of a punching operation, a grinding operation and an abrading operation, with the result that a plurality of different press dies have to be used and the operation is highly troublesome.
Also, the conventional press operation causes burrs to be produced on a blade of the needle due to the use of dies. Unfortunately, removal of burrs is time- and labor-consuming, therefore, the flow press operation or flow pressing which is said to prevent production of burrs on the blade during formation of the needle has been recently proposed, as disclosed in U.S. Pat. No. 4,044,814.
However, in order to form a metal blank into the blade of the sewing machine needle by flow pressing while preventing formation of burrs on the blade, it is essential that a volume of the metal of the blank flowing into a extraneous cavity formed between a pair of dies be reduced to an amount smaller than that of a volume of the cavity. Also, when the amount of the metal of the blank is very insufficient or the blade is formed with a long groove by coining which causes burrs to be formed on the blade, the strength and quality of the needle is decreased, and loss due to inferior products and manufacturing difficulties increase, leading to an increase in manufacturing costs.
Further, formation of a clearance-above-eye of an insufficient depth on the blade causes a loop of a sewing thread to be often formed into a small size when the thread is fed to the needle while being kept somewhat stretched, so that a looper is apt to fail to satisfactorily catch the loop. Thus, mounting of the sewing machine needle on a sewing machine requires troublesome operations such as adjustments of the sewing machine, including timing adjustment, adjustment of a feed dog or the like, so that handling and operation of the sewing machine require much time and labor.
DISCLOSURE OF INVENTION
The present invention has been made in view of the foregoing disadvantages of the prior art.
Accordingly, it is an object of the present invention to provide a sewing machine needle which is capable of exhibiting high quality while providing sufficient buckling strength and substantially preventing breakage of the needle.
It is another object of the present invention to provide a sewing machine needle which is capable of providing a gap of a large size between a blade and a sewing thread to facilitate the sewing operation and permit a sewing machine to be driven at a high speed.
It is a further object of the present invention to provide a method for manufacturing a sewing machine needle which is capable of readily and inexpensively manufacturing a sewing machine needle which exhibits sufficient strength and ensures a stable sewing operation at a high speed.
In accordance with one aspect of the present invention, a method for manufacturing a sewing machine needle is provided. The method comprises the step of forming a needle blank with a shank of a large diameter and a cylindrical shape, a first blade section of a diameter smaller than the shank contiguous to a distal end of the shank and a second blade section of a diameter smaller than the first blade section contiguous to a distal end of the first blade section, the first and second blade sections constituting the blade; forming the second blade section with an elongated portion corresponding to a clearance-above-eye of the sewing machine needle; and subjecting the blade to die pressing to form a long groove of a recessed shape extending from the shank to a portion of the second blade section in proximity to a needle point and a needle eye portion having a thin eye accommodating web arranged along the continuous groove, and
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patent: 4598753 (1986-07-01), Zylbert
Kojima Tsutomu
Takei Yoshitsugu
Nerbun Peter
Organ Needle Co. Ltd.
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