JPH11151562A - Plunger tip for die casting machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a plunger tip having high wear resistance in the surface layer formed on the sliding surface without detaching and recoverable through the re-treatment even in the case of wearing by executing build-up welding of Co base alloy on the sliding surface between the plunger tip and a plunger sleeve. SOLUTION: A build-up layer 1 composed of the wear resistant high Co base alloy is formed on the sliding surface A between with the plunger sleeve on the base material 2 of the plunger tip sliding in the inner peripheral wall of the plunger sleeve forming a hole in the inner part in the axial direction of the hole. The sliding surface A is formed so as to parallel extend to the axial line (x) of the hole of the plunger sleeve. The outer profile of the build-up layer 1 becomes the parallel straight line to the axial line (x). Non-welding part is eliminated between the base material 2 and the build-up layer 1 and the whole boundary surface is fully welded. Then, as the Co, base alloy, it is desirable to use the alloy containing 20-40 wt.% Cr and 0.3-1.5 wt.% W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plunger tip slidably disposed in a plunger sleeve of a die casting machine for injecting molten metal.

[0002]

2. Description of the Related Art In a die casting machine, a plunger tip and a plunger sleeve are consumables. Normal,
The plunger chip is manufactured by sequentially performing quenching, tempering, and heat treatment on a molded body made of JIS SKD61. The plunger tip has a hardness of about 450 HV and a life of about 10,000 shots (1
0 day).

[0003] On the other hand, the plunger sleeve is a large part and expensive, and is difficult to detach and attach.
Usually, it is designed to have a longer life than the plunger tip. That is, the plunger sleeve is
It is manufactured by sequentially performing quenching, tempering, and heat treatment on a molded body of S SKD61 material, and further performing a nitriding treatment. The plunger sleeve has a hardness of about 900 HV and a life of about half a year.

[0004] Normally, both the plunger tip and the plunger sleeve reach the end of their life when abrasion or scratches occur.
Cannot be reused. Here, since the life of the plunger tip is significantly shorter than that of the plunger sleeve, a longer life is required. As a plunger tip with a long life, a thermal spray material made of B-Cr-Mo is sprayed on the surface to improve the wear resistance.
A beryllium copper plunger tip has been developed which is entirely made of beryllium copper having high wear resistance.

FIG. 4 shows a vertical section of a thermal spray plunger tip. The thermal spray layer 21 is formed on the sliding surface A, and is formed on the corner B of the plunger tip to prevent peeling or cracking after thermal spraying.
Formed. However, in order to avoid cracking due to a difference in the coefficient of thermal expansion from the base material 22, the metal is not formed on the top C. FIG.
Represents the cross section of the thermal spray layer of the thermal spray plunger tip. Between the base material 22 and the sprayed layer 21, a welded portion 23 and a non-welded portion 24
Exists, and the thermal sprayed layer 21 is in a state of being easily peeled.

[0006] The sprayed plunger tip has a higher wear resistance than the non-sprayed plunger tip, and therefore has a long life and is about 2 times longer.
Up to 3,000 shots can be used, and even if the sprayed layer wears out, it can be used repeatedly by re-spraying,
It also reduces costs. JIS S45 cheaper base material
It is also possible to change to a material such as C. However, since the thermal sprayed layer is not completely welded to the base material, peeling from the base material is inevitable, and sufficient management of the replacement cycle is essential. In addition, when the sprayed layer is not allowed to be mixed into the product, the sprayed plunger tip cannot be used.

A beryllium copper plunger chip (for example,
Cu-2 to 2.5Be; the number represents weight%) has a longer life than the thermal spray plunger tip and can be used up to about 25,000 shots. However, beryllium copper plunger tips are expensive and cannot be used repeatedly by re-spraying like thermal spray plunger tips.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a surface layer (sprayed layer, build-up layer, plated layer, etc.) formed on a sliding surface with a plunger sleeve having high wear resistance. Re-processing (re-spray,
It is an object of the present invention to provide a plunger tip that can be repaired by rebuilding, replating, and the like.

[0009]

A plunger tip of a die casting machine according to the present invention is a plunger tip which slides in an axial direction of a hole in an inner peripheral wall of a plunger sleeve having a hole formed therein. A Co-based alloy is build-up welded on the sliding surface of the metal alloy (claim 1). As the Co-based alloy, 20 to 40% by weight of C
Those containing r and 3 to 20% by weight of W are preferably used (claim 2). The sliding surface may be formed so as to extend parallel to the axis of the hole (claim 3).

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As a Co-based alloy used in the present invention, 20 to 40% by weight of Cr and 0 to 20% by weight of W are used.
And 0.3 to 1.5% by weight of Si and 0.2 to 3% by weight
An alloy containing C is used. Among them, 20-40
It is preferable to use a Co-based alloy containing Cr of 3% by weight and W of 3 to 20% by weight. In particular, the total amount of Cr and W in the Co-based alloy is preferably 25 to 55% by weight. C
If the total amount of r and W is less than 25% by weight, the hardness is too small, and if it exceeds 55% by weight, the hardness is too large.

As a method of overlay welding of a Co-based alloy, a plasma arc method using powder as a filler material is preferably used in the following points. (a) Since a plasma arc having a high energy density is applied, powder can be used as a filler material. (b) By using powder as the filler, the content of each component in the filler can be freely adjusted. (c) Compared to arc welding (TIG, MIG, etc.), the amount of heat input can be reduced, so that the influence on the base material is small. (d) Compared to arc welding, the amount of fusion of the base metal on the weld surface is small, so the degree of dilution of the filler metal by the base metal is small, and its function (excellent wear resistance, etc.) is sufficient for the overlay welding layer. Can be demonstrated. (e) The filler metal (facing layer) deposited on the base material does not peel off. (f) The filler metal (facing layer) deposited on the base material can be used repeatedly by resurfacing even if worn. (g) The base material can be changed to a cheaper material such as JIS S45C.

FIG. 1 shows a vertical section of the plunger tip of the present invention. Hardfacing layer 1 made of Co-based alloy with high wear resistance
Is formed on the sliding surface A of the base material 2 with the plunger sleeve (not shown). No overlay layer is formed on the corners B and the tops C. The sliding surface A of the plunger tip that slides on the inner peripheral surface of the hole of the plunger sleeve is formed so as to extend parallel to the axis x of the hole of the plunger sleeve. That is, on the cut surface including the axis x of the hole of the plunger sleeve, the outer contour of the build-up layer is a straight line parallel to the axis x. FIG. 2 shows a cross section of the cladding layer of the plunger tip of the present invention. Between the base material 2 and the overlay 1
There are no welds and all interfaces are completely welded.

The build-up welding may be performed on the sliding surface with the plunger sleeve, and the build-up layer can be formed by a single welding process. However, as shown in FIG. 1, the corner a of the plunger tip is covered with a welding bead in order to prevent wear due to sliding.
The hardness of the overlay is 300 to 600 HV so as not to damage the plunger sleeve.

FIG. 3 shows the structure around the die of the die casting machine.
Shown in In FIG. 3, a mold 12 fixed to a mold fixing plate 11 is shown.
And a cavity 14 for molding a metal product is formed between the movable molds 13 and 13 '. When the plunger tip 16 slides in the plunger sleeve 15 disposed so as to penetrate the mold fixing plate 11 and the mold 12, the molten metal 19 injected by the ladle 18 through the molten metal injection port 17 forms a cavity. , And is solidified by being extruded into the plunger tip 16 and the movable mold
3, 13 'retracts and is taken out as a metal product.

[0015]

EXAMPLE 1 A cobalt alloy (Co-28Cr-4.3W-1.2Si-1.1C; Co-28Cr-4.3W-1.2Si-1.1C;
(The numbers represent% by weight) were overlaid with a plasma arc build-up welding machine (180 A AC, argon plasma). The formed overlay layer has a thickness of about 2.5 mm,
The surface hardness was about 350 HV. After finishing this plunger chip, when it was used in a die casting machine, it could be used up to about 15,000 shots (15 days). During this time, the plunger sleeve was not damaged.

Example 2 A sliding surface of a plunger tip subjected to normalizing treatment of JIS S45C was coated with a cobalt alloy (Co) having an average particle diameter of 150 μm.
-30Cr-8W-1.2Si-1.5C; the numbers represent% by weight) with a plasma arc build-up welding machine (AC 180
A, argon plasma). The formed build-up layer had a thickness of about 3.0 mm and a surface hardness of about 450 HV. After finishing this plunger chip, it was used in a die casting machine.
Use up to 5,000 shots (15 days) was possible. During this time, the plunger sleeve was not damaged.

[0017]

The plunger tip of the present invention has a long life, does not peel off the build-up layer formed on the sliding surface, and can be used repeatedly by rebuilding even if the build-up layer is worn. In addition, the build-up layer is excellent not only in wear resistance but also in corrosion resistance and heat resistance.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a plunger tip of the present invention.

FIG. 2 is a sectional view of a cladding layer of the plunger tip of the present invention.

FIG. 3 is a view showing a structure around a die of the die casting machine.

FIG. 4 is a longitudinal sectional view of a conventional thermal spray plunger tip.

FIG. 5 is a sectional view of a thermal spray layer of a conventional thermal spray plunger tip.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 overlay layer 2 base material 11 mold fixing plate 12 mold 13, 13 ′ moving mold 14 cavity 15 plunger sleeve 16 plunger tip 17 molten metal injection port 18 ladle 19 molten metal 21 sprayed layer 22 base material 23 welding part 24 Non-welded portion A Sliding surface a Corner B Corner C Top x-axis

Claims (3)

[Claims] 1. A plunger tip that slides in the axial direction of a hole in an inner peripheral wall of a plunger sleeve having a hole formed therein, wherein a Co-based alloy is overlay-welded to a sliding surface with the plunger sleeve. Plunger chip for die casting machine. 2. The plunger tip according to claim 1, wherein said Co-based alloy contains 20 to 40% by weight of Cr and 3 to 20% by weight of W. 3. The plunger tip according to claim 1, wherein said sliding surface extends parallel to an axis of said hole.