JPH04295397A - Shuttle body of half-rotation sewing machine - Google Patents

Abstract

PURPOSE:To prevent the strength of the shuttle body of a half-rotation sewing machine from being reduced by lowering of the hardness of a carburization hardening layer due to high-temperature heating employed when coating the shuttle body with layers of superhard materials such as TiN, TiC in order to deal with high-speed stitch. CONSTITUTION:In the cross section of a shuttle body, the surface of a hardened layer 5 formed on a base material 4 by carburization hardening is covered with two layers of a hard chrome layer 6 and a super-hardened layer 7 of TiN or TiC, etc.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner hook for a half-turn sewing machine.

0002

[Prior Art] The manufacturing process for the inner hook of a conventional half-rotation sewing machine generally involves cutting a formed material by cold press forming or hot forging, surface hardening heat treatment (carburizing and quenching), polishing, cloth processing, etc. The process was completed. Conventional medium-sized pots are slower than full-rotation pots, and for home use, the speed is at most 1,000 mph per minute.
Although it is a rotating (reciprocating) process, high speeds are gradually required for industrial use, and some machines reach 2000 rotations or more. Conventionally, the diameter of the sliding band 2 for inner pots is specified by JIS as 42.6 mm, which is larger than that for full-rotation pots, and it is structurally impossible to install a lubrication device, which generates a large amount of heat due to sliding. Problems such as abrasion and seizure occurred with the cauldron. For this reason, for industrial pots that require high speed, the surface is hardened by carburizing and quenching as described above, and then hard chrome plating is applied after polishing. However, hard chrome plating has low frictional resistance and good wear resistance when lubricating oil is present, as in the case of full-turn sewing machines, but in the case of half-turn sewing machines, lubricating oil cannot be supplied. It generates a lot of heat, making it impossible to achieve higher speeds, and the sliding groove of the large hook, which guides the sliding movement of the inner hook, wears out, reducing its lifespan.Furthermore, the metal powder generated by this wear contaminates the fabric. There are problems such as In order to solve these problems, inner pots are also manufactured which are coated with ultra-hard wear-resistant materials such as TiN (titanium nitride) and TiC (titanium carbide) by ion plating or the like after carburizing and quenching and polishing.

0003

Problems to be Solved by the Invention Although the inner pot coated with the above-mentioned coating has been evaluated as being extremely excellent in terms of reduction in driving torque, reduction in heat generation, and improvement in wear resistance, it has the following drawbacks. In other words, in the ion plating method, the base material (inner pot) is used to improve the adhesion of the coating material.
Since the steel is heated to 450° C. or higher, the hardness of the carburized and quenched layer 5 decreases due to the tempering effect, causing problems in terms of strength. In particular, the tip 3 of the inner hook frequently comes into contact with or collides with the needle, which has a high hardness, so the tip, whose hardness has decreased, will suffer damage due to abrasion, fatigue, etc. within a short period of time, shortening the life of the inner hook. There is. The industry has long desired a solution to this problem.

0004

[Means for Solving the Problems] In the present invention, the processing steps are roughly performed in the order of machining, carburizing and quenching, polishing, and hard chrome plating, and finally a coating of ultra-hard TiN, TiC, etc. is applied.

[0005]

[Function] Even if the hardness of the carburized and quenched layer 5 decreases due to heating to 450°C or higher to improve its adhesion during coating, the hardness will not decrease even if the outside is heated to this temperature. Since it is covered with a hard chrome plating layer 6 of high hardness, this acts as a protective layer to maintain strength, and furthermore, the outermost TiN and TiC layer 7 acts as an abrasion resistant layer, thereby solving the above-mentioned drawbacks.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be explained with reference to the drawings. The inner hook 1 of the half-rotation sewing machine reciprocates half a rotation guided by a sliding band 2 rotatably fitted in a sliding groove of a large hook (not shown). The tip 3 captures a needle thread loop (not shown) formed at the tip of the needle (not shown), and stores it in a bobbin case (not shown) housed in the inner hook. It has a mechanism that forms stitches with the bobbin thread wound around the bobbin. When the tip 3 captures the needle thread loop, the tip of the tip 3 frequently contacts or collides with the needle due to the mechanism. Conventionally, half-rotating pots have been manufactured by performing processes such as cutting, surface hardening heat treatment (carburizing and quenching), polishing, and fabric processing on formed materials by cold press forming or hot forging, etc., as described above. However, in the present invention, as shown in the enlarged cross-sectional view of FIG. 1, after conventional machining, a carburized and quenched layer 5 with a surface hardness of about 800 Vicars and a hardening depth of about 0.2 mm is provided on the surface of the base material 4, and then baked. After performing back treatment and polishing, a hard chrome plating layer 6 of approximately 0.02 mm to 0.03 mm is applied, and the surface of this is further plated to a thickness of 0.0 mm by ion plating.
A TiN layer 7 having a thickness of about 0.02 mm to 0.03 mm was coated.

[0007]

[Effects of the Invention] As a result of the above treatment, (1) the first TiN layer 7 acts as an abrasion resistant layer, and the second hard chrome plating layer 6 becomes the third carburized and quenched layer 5 by heating in the ion plating process; Since the strength deteriorates due to a decrease in hardness, it is reinforced from the surrounding area, resulting in extremely high rigidity, which prevents the tip from breaking as described above. (2) The presence of the second hard chromium layer 6 allows ion plating at high temperatures, improving the adhesion of the TiN layer and eliminating defects such as peeling. ■ TiN and TiC have a small coefficient of friction and generate less heat, so they can operate at speeds of 2000 revolutions per minute or more for long periods of time.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of an inner pot according to the present invention.

FIG. 2 is a front view of the inner pot.

FIG. 3 is a side view of the inner pot.

[Explanation of symbols]

１　　　　Middle pot 2 Sliding belt 3 Sword tip 4 Base material 5 Carburized and quenched layer 6 Hard chrome plating layer 7 TiN layer

Claims (1)

[Claims] Claim 1: A carburized and quenched layer (
A hard chrome plating layer (6) is applied to the outside of 5), and furthermore, TiN (titanium nitride) and TiC (titanium carbide) are applied to the outside of the hard chrome plating layer (6).
An inner hook for a semi-rotary sewing machine, characterized in that it is coated with a layer (7) made of an ultra-hard material such as.