JPS6169424A - Corrosion-and wear-resistant screw and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a screw, which has higher corrosion resistance and higher wear resistance and consequently the scope of application of which is enlarged, by a method wherein powder build-up welding is performed while holding molten matter bythe side surface of a mold. CONSTITUTION:In an injection molding screw having a spiral thread onto the outer periphery of a shank, the surface of the flank of the thread is cladded with a build-up layer scatteringly holding hard particles in a base metal such as cobalt base alloy, iron base alloy, nickel base alloy or alloy of cobalt, iron and nickel by means of powder build-up welding, the progressing direction of which is along the longitudinal direction of said thread. Thus, the thread of the screw has a build-up layer cladded by means of powder build-up welding, the progressing direction of which is along the longitudinal direction of the thread. Because the build-up layer is made by welding and consequently tightly fixed to base material with strong bonding strength and at the same time through diffusion layer, thermal stress or the like is scattered through the diffusion layer and consequently no separation of the build-up layer develops.

Description

[Detailed description of the invention] Fields of use in filial piety The present invention relates to plastic and plastimagnets.

Weld overlay screws with particularly excellent corrosion and wear resistance for injection molding machines for rubber magnets, ceramics, etc.
(hereinafter referred to as "Scuri 21") and its manufacturing method.

Conventional technology For screws for plastic injection molding machines, for applications that require a particularly high degree of corrosion resistance and abrasion resistance, for example, Hastelloy materials have been used for Teflon resin molding, which has a particularly strong corrosive effect, and For example, high C and high Cr special steels are used in applications where high properties are required.

However, in recent years, there has been an increase in the use of resins containing fillers, and materials that are even more abrasive than before, such as plastic magnets and ceramics, which have particularly abrasive effects.

In contrast, injection molding has come to be used, and screws made of the above-mentioned special steel are no longer able to meet the requirements for wear resistance.

For this reason, it has been proposed to apply thermal spray overlay or weld overlay using a welding rod to the surface of the base material.

However, since the former is thermal spraying, the build-up layer is simply built-up on the surface of the base material without any or almost no melting, and the bonding force with the base material is extremely low.
It is not widely adopted because it easily peels off and the bonding force inside the built-up layer is weak, resulting in low wear resistance.

The latter uses a welding rod, which has a strong bond with the base metal, but there are restrictions on the composition and diameter of the welding rod due to the manufacturing aspects of the welding rod. Difficult to obtain layers. In addition, welding rods are very expensive and require a large number of build-up man-hours, and with this build-up method, especially when using a thick welding rod, it is difficult to build up the edges of a chevron-shaped cross section at an acute angle. Therefore, the finishing grinding allowance increases, a large number of grinding man-hours are required, and the manufacturing cost of these K-shaped screws becomes extremely high, so that the range of application is greatly restricted.

The problem that the invention aims to solve is the original one! The purpose of the present invention is to provide a screw that has 1llIFi, high corrosion resistance, high wear resistance, and has an expanded range of application.

Means for Solving the Problem - The present invention can be applied to carbon steel, structural alloy steel, hot work tool steel, cold work tool steel,
Using a base material such as stainless steel, powder build-up welding proceeds along the longitudinal direction of the mountain to form a CO group + Ni group or Fe of a solidified structure extending with a longitudinal component.
A base K′Wc+ TI consisting of a base or an alloy thereof
Cr T iN r T iB 21 V C+ C
Corrosion resistant with built-up layer in which hard material particles such as r γCs tAt20, St Q*, and Zr 02 are dispersed and held;
This is a screw manufacturing method in which a mold made of refractory is provided on the side of the wear-resistant screw and the ridge portion, and powder build-up welding is performed while holding the molten material on the side of the mold.

Function The screw crest of the present invention has a built-up layer formed by powder build-up welding that progresses along the longitudinal direction of the crest. This built-up layer is formed by welding and is fixed to the base metal with strong bonding force through the diffusion layer, so thermal stress etc. are dispersed by the diffusion layer and there is no peeling. Moreover, since this overlay hw4 is made of a molten powder obtained by melting each component and the blending ratio thereof, the abrasion resistance can be made sufficiently high. Furthermore, the solidified structure of the built-up layer on the crest of the screw, which requires high wear resistance, is a solidified structure that extends with a component in the advancing direction of the built-up, that is, the longitudinal direction of the crest.
Since the longitudinal component of this mountain coincides with the direction of friction with the material to be injected, it exhibits particularly high wear resistance.

In the method of the present invention, a mold made of refractory material is provided on the side of the part that will form a mountain, and powder build-up welding is performed while holding the molten material on the side of this mold, so that the molten material does not flow out of the part on the mountain side. Since it prevents spreading, it is possible to sharpen the ridge of the mountain cross section and prevent overfilling. This makes it possible to reduce the amount of raw material powder used, and also to reduce the number of finishing steps, which require a particularly large number of steps.

Examples Table 1 shows examples of combinations of the screw base material and overlay material in the present invention, the hardness of the overlay layer, and comparison results of corrosion resistance and wear resistance with conventional 5KD11 as a comparative material. Table 2 also shows the composition of each alloy used.

Table 1 Table 2 Regarding corrosion resistance, that of conventional special steel 5KD11 was 10
The screw materials of the present invention, which are made by overlaying a composite of a sterai)+Ni alloy, a Ni-containing iron-based alloy, or a composite of these and hard particles, have significantly superior corrosion resistance to 5KD11. On the other hand, regarding wear resistance, the wear loss of 5KD11 was reduced by 10%.
The overlay alloys for screws according to the invention K of the present application exhibit significantly excellent wear resistance, except for the case of low-hardness Ni alloys which are further subjected to electric furnace corrosion resistance.

This is because stellite-based and colmonoid-based alloys inherently have excellent wear resistance, and furthermore, depending on the alloy, dispersed particles such as hard carbides are distributed.

Regarding the influence of hard particles on abrasion resistance, there is a tendency for particles with higher hardness and a larger number of dispersed particles to have greater abrasion resistance.

Next, a method for manufacturing the screen of the present invention will be explained based on drawings of embodiments.

First, a rod-shaped material is quenched and phosphorus-restored to hardness HRC 34), and then a base material 1 having a trapezoidal chevron portion 2 of a small cross section connected in a spiral shape is cut out, and the bottom portion 3 of the base material 1 is welded with powder overlay. A shaft material 4 having a valley built-up layer 3' was produced. next,
This shaft material 4 was maintained at a constant low temperature, immersed in molten solder at a constant temperature for a certain period of time, and then pulled up, thereby coating the entire surface with a solid solder layer having a constant thickness. Subsequently, the wax on the surface of the valley fill-up layer 3' of this solder layer was manually scraped off, and the process of soaking, pulling up and drying was repeated to cover the zirconia sandonite layer. Subsequently, this coating layer was formed into a spiral mold 5 by cutting out the top of the chevron portion 2, and then heated to remove wax. front of.

The welding was performed continuously on the rear surface and the top using a plasma powder build-up welding device. The figure shows a state in which overlay welding is performed on the front surface of the chevron part, and 6 is a torch. The torch 6 was tilted to match the angle of the back surface of the mountain. In either case, the shaft member 4 was fed and rotated in the axial direction so that build-up welding continued in the longitudinal direction of the mountain. The build-up work was carried out smoothly, and the amount of bending that occurred was able to be absorbed by the final grinding, and this is thought to be due to the continuous build-up in the constant moxibustion process, which suppressed the occurrence of bends. . In addition, as a result of a cross-section inspection of the built-up layer, it was found that the weld penetration was sufficient and no cracks were observed.

In this embodiment, the base material 1 is provided with the chevron-shaped portion 2, and has the characteristics that there is little build-up, and this also reduces the occurrence of bending and is advantageous in terms of the strength of the heap.

In the above embodiment, the mold is formed by using a wax layer and coating with slurry, but instead of wax, a sheet of paper, rubber material, etc., or a sheet of this sheet assembled into a desired cross-sectional shape is used. Furthermore, the mold may be one in which segments are manufactured by press molding or the like independently of the shaft member 4 and assembled onto the shaft member 4 by an appropriate method. .

By the method of the above example, an outer diameter of 50 mm, a length of 600 mm,
Comparison of man-hours when powder overlaying a 70wt% WC Ni alloy on a screw with 10 peaks and a height of 10+r- without using a mold shows that the overlay man-hours are 115. Finish grinding time reduced to 11
They were able to reduce each to 5.

Effects of the Invention As described above, the screw of the present invention is built-up welded by powder build-up welding along the longitudinal direction of the crest, so it is difficult to build up the screw by welding by conventional thermal spraying or welding using a welding rod. It has much higher wear resistance than a raised screw. The method of the present invention, which holds the molten material in a mold and performs powder build-up welding, can prevent unnecessary build-up and can significantly reduce the number of manufacturing steps. Therefore, both have high practical value.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of one embodiment of the method of the present invention. 0 1: base material, 2: chevron portion. 3.3': Valley and valley fill layer, respectively. 4: Shaft material, 5: Mold, 6: Plasma torch inspection / Fig. 3 3' Procedural amendment (method), □6h 2..25g 1981?1 Xuden 1 No. 193399 NJ. Invention 0 Name Corrosion-resistant and wear-resistant screws and warpage manufacturing method bll 11" Blue screw text and its manufacturing method" Correct Q
,/, ,7. ,. (,・°− Procedural amendment (voluntary)

Claims (2)

[Claims] 1. In an injection molding screw having a helically connected ridge on the outer periphery of the shaft, the surface of the ridge is coated with Co-based alloy, Fe
A corrosion-resistant and wear-resistant screw characterized by having a base alloy, a Ni-based alloy, or a base made of these alloys, and a built-up layer that disperses and holds hard particles. 2. In a method for manufacturing an injection molding screw that has a spiral ridge on the outer periphery of the shaft, a refractory mold is provided on the side of the ridge, and the molten material is held on the side of the mold. A method for manufacturing a corrosion-resistant and wear-resistant screw characterized by powder overlay welding.