JP2004066240A - Cylinder for injection-molding machine for light alloy - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylinder for an injection-molding machine for light alloy of which the base material secures heat-resistance and high temperature strength and of which the manufacturing cost is lower than that of a conventional cylinder. <P>SOLUTION: In the cylinder for the injection-molding machine for light alloy in which a coating layer made of erosion-resistant material is deposited on the inner surface of the hollow cylindrical base material for the cylinder, the base material for cylinder is formed by joining front cylinder base material disposed at the injection outlet side with back cylinder base material disposed behind the front cylinder base material in the longitudinal direction. The front cylinder base material is made of a nickel-based heat-resistant alloy and the back cylinder base material is made of an iron-based material. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a cylinder used in an injection molding machine that heats, stirs and melts a material to form a product by injecting it into a mold in a molten or semi-molten state for injection molding of a light alloy such as magnesium and aluminum. It is about.
[0002]
[Prior art]
Cylinders used in magnesium alloy injection molding machines reach a high temperature of about 650 ° C. during use, so that they are required to have heat resistance and are required to have erosion resistance to molten magnesium alloys. As a cylinder for an injection molding machine for injecting a light alloy such as magnesium of this kind, for example, Japanese Patent No. 2862799 discloses that a cylinder base material is formed of a nickel-base heat-resistant alloy, and a cobalt-base heat-resistant alloy is formed on the inner surface of the cylinder base material. Is disclosed.
[0003]
[Problems to be solved by the invention]
Nickel-base heat-resistant alloys, which are cylinder base materials, have high quality reliability and are excellent in heat resistance and high-temperature strength because their manufacturing processes such as melting and casting are precisely controlled. However, since a large amount of nickel, which is an expensive element, is used, the material cost is high, and since it is a difficult-to-cut material, the cost required for machining tends to be high. Therefore, when the cylinder base material is made of a nickel-base heat-resistant alloy over the entire length of the cylinder product as in Japanese Patent No. 2862799, there is a problem that the production cost of the cylinder product increases.
[0004]
Accordingly, an object of the present invention is to provide a cylinder for a light alloy injection molding machine capable of securing the heat resistance and high-temperature strength of a cylinder base material and reducing the production cost as compared with the related art.
[0005]
[Means for Solving the Problems]
In a cylinder for a light alloy injection molding machine, the front part closer to the tip of the injection outlet side of the cylinder is in a higher temperature range than the part behind it and a high injection internal pressure is applied, so sufficient heat resistance and durability are achieved. is necessary. Therefore, the present inventors have found that the rear portion of the cylinder can be sufficiently used even if the heat resistance and the durability are somewhat inferior to the front portion of the cylinder, and have completed the present invention.
[0006]
The light alloy injection molding machine cylinder of the present invention is a light alloy injection molding machine cylinder in which a coating layer made of a erosion-resistant material is formed on the inner surface of a hollow cylindrical cylinder base material. The front cylinder base material placed in the front and the rear cylinder base material placed behind it are joined in the longitudinal direction, the front cylinder base material is a nickel-base heat-resistant alloy, and the rear cylinder base material is iron. It is characterized by being made of a base material.
[0007]
In the present invention, the iron-based material forming the rear cylinder base material is made of austenitic steel or heat-resistant austenitic steel. Further, the difference between the average thermal expansion coefficient of the front cylinder base material and the rear cylinder base material from room temperature to 650 ° C. is within 5 × 10 ⁻⁶ / ° C.
[0008]
Further, the coating layer formed on the inner surface of the cylinder base material may be made of a cobalt-based alloy, an iron-based alloy, a cermet-based material in which ceramics are dispersed in a cobalt-based alloy, or a cermet-based material in which ceramics are dispersed in an iron-based alloy. It is characterized by comprising. Further, the front cylinder base material and the rear cylinder base material are joined by the HIP method. Further, the invention is characterized in that the coating layer is joined to the inner surface of the cylinder base material by the HIP method.
[0009]
The cylinder according to the present invention is configured such that the cylinder base material is divided into two or more regions in the longitudinal direction, that is, the front portion is disposed adjacent to the injection nozzle provided in front of the cylinder and disposed in the region where the injection internal pressure is high. A nickel-base heat-resistant alloy excellent in high-temperature strength and creep resistance is used as a cylinder base material. Further, as a rear cylinder base material disposed behind the front cylinder base material, an iron-based material having similar thermal characteristics to a nickel-based heat-resistant alloy and having a lower material cost than a nickel-based heat-resistant alloy is used.
[0010]
The basic form of the cylinder preform of the present invention comprises one front cylinder preform and one rear cylinder preform. However, for example, a plurality of front and rear cylinder preforms are respectively formed in the longitudinal direction so that one front cylinder preform and two rear cylinder preforms are joined to produce the entire cylinder preform. You may separate and comprise.
[0011]
As the nickel-base heat-resistant alloy of the front cylinder base material, for example, alloys represented by Inconel 718, Inconel 706, Inconel X-750 and the like are desirable.
[0012]
When joining cylinder base materials of different materials in the longitudinal direction, when subjected to a solution heat treatment and aging treatment after joining, and a thermal cycle acting during injection, if there is a difference in thermal expansion coefficient of the cylinder base material, Thermal stress and residual stress are generated in the joint and the coating layer on the inner surface of the cylinder base material. This stress is likely to cause a crack or the like in the thin coating layer.
[0013]
Nickel-base heat-resistant alloys have a larger coefficient of thermal expansion than ordinary steel materials. For example, for Inconel 718, the coefficient of thermal expansion between room temperature and 650 ° C. is about 15 × 10 ⁻⁶ / ° C. In order to reduce the above-mentioned thermal stress and residual stress, it is necessary to use a material having a thermal expansion coefficient close to this.
[0014]
The difference in the coefficient of thermal expansion between the front cylinder base material and the rear cylinder base material from room temperature to 650 ° C. is within 5 × 10 ⁻⁶ / ° C., more preferably within 3 × 10 ⁻⁶ / ° C. preferable. As the rear cylinder base material, for example, an austenitic steel such as SUS304 or SUS316, or an austenitic heat-resistant steel such as SUH309 or SUH310 is desirable. These have high strength at high temperatures and can be sufficiently used except in the region of the tip of the cylinder.
[0015]
In the case where the front cylinder base material and the rear cylinder base material are joined in the longitudinal direction, the front cylinder base material and the rear cylinder base material are stacked in the longitudinal direction as in an example described later, and the two base materials are joined together. The end faces of the materials are joined to each other. Also, a male screw (or female screw) is engraved on the front cylinder base material, and a female screw (or male screw) is engraved on the rear cylinder base material. May be. The latter is preferable because the two base materials can be joined more firmly.
[0016]
The alloy coated on the inner surface of the cylinder base material is desirably one of a cobalt-based alloy, an iron-based alloy, a cermet-based material in which ceramics are dispersed in a cobalt-based alloy, and a cermet-based material in which ceramics are dispersed in an iron-based alloy. These materials are excellent in erosion resistance to molten metal such as magnesium, and have abrasion resistance, high-temperature strength, and the like, and can extend the life of members for injection molding machines.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic sectional view of a cylinder for a light alloy injection molding machine according to the present invention. In FIG. 1, a cylinder body 1 includes a hollow cylinder-shaped cylinder preform 4 formed by joining a front cylinder preform 2 and a rear cylinder preform 3 on concentric axes, and a molten metal of the cylinder preform 4. Is formed by forming a coating layer 5 made of a erosion-resistant material on the inner peripheral surface in contact with.
[0018]
First, Cr: 19%, Mo: 3%, Fe: 19%, Nb: 5%, Ti: 0.8%, Al: 0.5%, and Ni: the remaining nickel-based heat-resistant steel were used in terms of% by weight. A hollow cylindrical front cylinder base material 2 having an outer diameter of 150 mm, an inner diameter of 45 mm, and a length of 300 mm was produced. The front cylinder base material 2 has an average thermal expansion coefficient from room temperature to 650 ° C. of 15.0 × 10 ⁻⁶ / ° C.
[0019]
Next, using an austenitic steel material consisting of Si: 0.3%, Mn: 1.5%, Ni: 8%, Cr: 18%, Fe: balance by weight%, outer diameter 150 mm, inner diameter 45 mm, length A 400 mm-thick hollow cylindrical rear cylinder base material 3 was produced. The rear cylinder base material 3 has an average thermal expansion coefficient from room temperature to 650 ° C. of 19.0 × 10 ⁻⁶ / ° C.
[0020]
Next, a mandrel was placed at the center of the HIP can, and a front cylinder base material 2 and a rear cylinder preform 3 were inserted into the outer periphery of the metal core and stacked in the longitudinal direction. Then, in a gap having a width of about 3 mm formed between the outer surface of the core metal and the inner surfaces of the front cylinder base material 2 and the rear cylinder base material 3, Si: 1% by weight as a coating layer 5; A cobalt-based alloy powder consisting of Mn: 1%, Cr: 20%, B: 3%, and Co: balance was filled.
[0021]
HIP processing was performed in the state set in this way. After the HIP treatment, the core metal is removed, and a coating layer 5 made of a cobalt-based alloy is formed on the inner surface of a cylinder base material 4 in which the front cylinder base material 2 and the rear cylinder base material 3 are concentrically joined. The cylinder body 1 on which was formed was taken out and subjected to predetermined machining to obtain a cylinder for a light alloy injection molding machine of the present invention.
[0022]
Inspection of the joint surface between the front cylinder base material 2 and the rear cylinder base material 3 and the joint surface between the cylinder base material 4 and the coating layer 5 by penetrant inspection showed that defects such as cracks were not recognized and sound. Had been joined. In addition, the cylinder for a light alloy injection molding machine of the present invention significantly reduces the manufacturing cost over the entire length of the cylinder base material as compared with a conventional cylinder made of a nickel-base heat-resistant alloy, which is expensive in material and processing costs. did it.
[0023]
By using the cylinder for a light alloy injection molding machine of the present invention, magnesium whose temperature during use is 600 to 650 ° C. in a range of about 200 mm from the front end face of the injection outlet side of the cylinder, and less than 600 ° C. in a region behind it. Injection molding of the alloy was tested in an actual machine, and it was confirmed that there was no occurrence of erosion or abrasion in long-term use, and that the alloy was excellent in durability.
[0024]
【The invention's effect】
According to the cylinder for a light alloy injection molding machine of the present invention, while having properties such as heat resistance, high temperature strength, erosion resistance, and wear resistance required as a member for an injection molding machine of molten metal such as magnesium, It is possible to obtain a light alloy injection molding machine cylinder that can reduce the manufacturing cost as compared with the related art.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a cylinder for a light alloy injection molding machine of the present invention.
[Explanation of symbols]
1 cylinder body, 2 front cylinder base material, 3 rear cylinder base material,
4 cylinder base material, 5 coating layer

Claims (6)

In a cylinder for a light alloy injection molding machine in which a coating layer made of a erosion-resistant material is formed on the inner surface of a hollow cylindrical cylinder base material, the cylinder base material is a front cylinder base material disposed on the injection outlet side, and thereafter. Light alloy injection, characterized in that the rear cylinder base material is joined in the longitudinal direction, the front cylinder base material is made of a nickel-based heat-resistant alloy, and the rear cylinder base material is made of an iron-based material. Cylinder for molding machine. The cylinder for a light alloy injection molding machine according to claim 1, wherein the iron-based material forming the rear cylinder base material is made of austenitic steel or austenitic heat-resistant steel. The difference between the average thermal expansion coefficient of the front cylinder base material and the rear cylinder base material from room temperature to 650 ° C. is within 5 × 10 ⁻⁶ / ° C. 3. Cylinder for light alloy injection molding machine. The coating layer formed on the inner surface of the cylinder base material is made of one of a cobalt-based alloy, an iron-based alloy, and a cermet-based material in which ceramics are dispersed in a cobalt-based alloy or an iron-based alloy. The cylinder for a light alloy injection molding machine according to any one of claims 1 to 3. The cylinder for a light alloy injection molding machine according to any one of claims 1 to 4, wherein the front cylinder base material and the rear cylinder base material are joined by a HIP method. The cylinder for a light alloy injection molding machine according to any one of claims 1 to 5, wherein the coating layer is joined to an inner surface of the cylinder base material by a HIP method.

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