JPS58169492A - Production of outer hook of sewing machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing outer hooks such as vertical full-turn hooks and horizontal full-turn hooks for sewing machines.

Generally, when sewing with a sewing machine, the needle moving up and down and the tip of the outer hook used to catch the thread may come into contact or collide. As a result, the tip of the sword may be damaged or deformed, leading to eye and thread breakage. In the prior art, in order to solve this problem, a super hard material made of powdered sintered alloy is joined to the outer hook body by brazing to form the tip. Due to the high strength of hardwood, the cutting process after joining is a rectangle, reducing the cost per piece. Also, because of brazing, the strength and reliability of the connection between the outer hook body and the tip of the sword is poor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing an outer hook for a sewing machine, which makes it possible to form a high-strength tip with easy work and improved productivity.

FIG. 1 is a plan view of a vertical full-rotation rotary rotary rotary rotary hook according to an embodiment of "Unexploded". A boss 2 is formed on the outer hook 11, and the outer hook 11 is rotated about an axis extending vertically in FIG. A hook 4 is formed on the outer hook IK.

A tip 5 is formed at the tip of the hook 4. A spring 6 is attached to the outer hook 1 with a screw.

A method for manufacturing the tip 5 will be explained with reference to FIG. The main body of the outer case, including the hook 4 and boss 2, is made of case-hardened steel such as carbon case-hardened steel or chrome-molybdenum case-hardened steel, and is formed by precision casting, forging, cutting, etc. be done. The outer shank body may be made of materials other than case hardened steel. As shown in FIG. 2 (11), the tip of the hook 4 into which the tip 5 is to be formed is formed by cutting or the like.

Therefore, as shown in FIG. 2 (2), a thin material of martensitic thread high chromium steel is welded using a welding rod 8 near the tip 5 to be formed. This N build-up welding is performed by plasma welding or the like. As a result, it is formed with the required minimum build-up or high adhesion strength between the martensitic thread high chromium steel and the case hardened steel that makes the outer body. A reference mark 9 indicates a built-up welded portion formed by welding.

The build-up welded portion 9 is shaped into the shape of the tip 5 by cutting, as shown in FIG. 2(3).

The strength of the outer case 1 on which the tip 5 is formed is further improved by heat treatment such as hardening.

Martensitic yarn high chromium steel generally changes from an austenitic state at high temperatures during heat treatment to an austenite state when rapidly cooled.
Toughness is imparted by hardening martensite and burning ashes. Therefore, the tip 5 has excellent impact resistance and abrasion resistance. Since the spun martensitic yarn high chromium steel has good plasticity during cold forming, it is easy to cut the build-up weld part 9 into the shape of the sword tip 9. The welding work for forming it is also easy.

The invention can not only be implemented in connection with a vertical full-rotating hook, but also in conjunction with a horizontal full-rotating hook.

As described above, according to the present invention, martensitic thread high chromium steel is welded overlay to the portion of the outer hook body where the tip is to be formed, and then the welded portion is cut to form the tip. As a result, the tip is shock-resistant and abrasion-resistant (ψ), which prevents the tip from being damaged or deformed even if it comes into contact with or collides with the needle. This prevents triggering and improves m-manufacturing performance.

In the present invention, there is no need to braze the cemented carbide as in the prior art described above, and therefore machining is easy and sufficient strength can be obtained at the joint between the tip and the outer hook body.

[Brief explanation of the drawing]

Figure 1 is a plan view of an example of "no explosion," Figure 2 is a top view of the sword tip 5.
FIG. l...outer hook, 3...inner hook, 4...hook, 5...
・Sword tip, 9... Overlay welding part agent Patent attorney Kei Nishi (5) 1ξQ Figure 1 Figure 2 Figure 1

Claims (1)

[Claims] +1) Prepare an outer hook body, overlay weld martensitic high chromium steel to the location where the tip of the outer hook body is to be formed, and then attach the foot portion to which this overlay welding is applied. A method for manufacturing an outer hook for a sewing machine, characterized by forming a tip by cutting. (2) The method for manufacturing an outer hook for a sewing machine according to claim 1, wherein the build-up welding is performed by plasma welding. (3) Method for manufacturing an outer hook for a sewing machine according to item 1 or 2 of the patent claim, characterized in that the outer hook body is made of case-hardened steel.