JPS6136563A - Ceramics-metal compound cylinder - Google Patents

Abstract

PURPOSE:To prevent a liner from being broken by shrinkage-fit and from shifting and to improve the durability and reliability of a cylinder by providing a metallic thin film with axial notches adhering to the outer peripheral surface of a ceramic liner, and shrinkage-fitting the liner to the cylinder. CONSTITUTION:A soft metallic thin film 2 such as pure copper thin film adheres to the outer peripheral surface of a ceramic liner 1. The surface of the metallic thin film 2 is ground, and then a plurality of notches 4 are machined along the axis of the liner 1. The liner 1 is shrinkage-fitted to a metallic cylinder 3 to form a compound cylinder. In this arrangement, thermal expansion of the metallic thin film 2 is absorbed by the notches 4 to prevent breakage of the liner 1.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is applicable to cylinders whose inner surfaces are required to have wear resistance and corrosion resistance, such as plastics, ceramics, etc.
This invention relates to improvements in cylinders installed in injection/extrusion molding machines for magnetic powder and metal powder used in ferrite or rare earth magnets.

[Conventional technology]

In general, this type of cylinder is made of materials that are produced by wear due to friction when the material to be formed is transferred through the cylinder by a screw or blanker built into the cylinder, or by thermal decomposition of organic matter added with the material. Subject to corrosion.

For this reason, although the inner surface of the cylinder is nitrided or hard iron or nonferrous alloys are welded by centrifugal casting to provide wear resistance and corrosion resistance, the problem is that the service life is drastically shortened due to early deterioration. have.

In addition, when molding plastic-sized parts, if abrasion powder or corrosion powder generated from the inner surface of the cylinder gets mixed into the molded product, a problem arises in that electrical insulation, corrosion resistance, and strength deteriorate. Furthermore, in the molding of ceramics and metal powders that are sintered in the subsequent process, abrasion powder or corrosion powder on the inner surface of the cylinder will seriously deteriorate the sinterability after molding, and in some cases may even prevent sintering. Sometimes it makes it impossible.

For these reasons, #i! is used as a cylinder for injection/extrusion molding machines. ! A cylinder in which a liner made of ceramics such as alumina, silicon carbide, silicon nitride, and Norconi 7, which are highly wear-resistant and corrosion-resistant, is attached to the inner surface of the cylinder is being considered.

However, compared to metal materials for trench construction, ceramics have a fracture toughness value of less than CIO (brittleness), are not flexible, have a weak bending strength of 20 to 100 kg/ms, and have a thermal expansion coefficient of The characteristics of these ceramics, which are as low as 3 to 10 Xi O-''/''C, cause the following problems when attaching a ceramic liner to the inner surface of a steel cylinder or when using it.

[Problem that the invention seeks to solve]

To attach a ceramic liner to the inner surface of a steel cylinder, the inner diameter of the #l cylinder is made smaller than the outer diameter of the ceramic liner, and the steel cylinder is heated to a predetermined temperature. The inner diameter of the ceramic cylinder is larger than the outer diameter of the ceramic liner.
After installing the ceramic liner inside the steel cylinder,
A method of shrink-fitting is usually adopted by shrinking the steel cylinder as it cools.

However, with this method, if the cylindricity and straightness of the inner diameter of the steel cylinder and the outer diameter of the ceramic liner are not finished with high precision, concentrated load and bending stress will be applied to the ceramic liner due to shrink fit stress. may destroy the liner. In addition, when the cylinder is heated and used, the shrink fit stress is alleviated due to the small thermal expansion coefficient of ceramics, which may cause the liner to shift in the direction of the cylinder sleeve or create a gap between the mating surfaces of the cylinder and liner. , the liner may be destroyed by the internal pressure of the cylinder M#.

Further, a method is being considered in which a thin metal film is coated on the outer peripheral surface of a ceramic liner by thermal spraying or plating, and this liner is attached to the inner surface of a steel cylinder.

However, with this method, when the temperature when the cylinder is used becomes high, the expansion of the steel cylinder and thin metal film becomes larger than the expansion of the ceramic liner, and the shrink fit stress is alleviated. A similar problem arises.

An object of the present invention is to provide a ceramic-metal composite cylinder that has wear resistance and corrosion resistance, effectively prevents liner breakage, and significantly improves durability and reliability. shall be.

[Means for solving problems]

The present invention is a ceramic-metal composite cylinder in which a thin metal film having notches in the axial direction of the liner is coated on the outer peripheral surface of a ceramic liner, and this is attached to the inner surface of a steel cylinder by shrink fitting.

As for the material forming this cylinder, the ceramic liner uses ceramics having wear resistance and corrosion resistance, such as alumina, silicon carbide, silicon nitride, and zirconia.

The fR cylinder uses steel materials such as carbon steel and chromium-molybdenum steel.

The material for the thin film that adheres to the outer peripheral surface of the ceramic liner may be iron, iron alloy, nonferrous metal, or nonferrous metal alloy, preferably a soft metal material with a large coefficient of thermal expansion. For example, chromium.・Nickel-based austenitic steel, aluminum, aluminum-magnesium alloy, nickel, nickel-molybdenum alloy steel, brass, etc. are good.These materials have good workability and the coefficient of thermal expansion is larger than 18XIO-@/'C. .

Can the metal thin film be applied to the outer surface of the ceramic liner by thermal spraying or plating? After forming a thin film on the inner outer circumferential surface, finishing is performed to a predetermined outer diameter dimension by turning or AIU.

Next, a plurality of notches are formed in the metal thin film liner in the axial direction using a grinder or a cutting tool.

This liner is then shrink-fitted into the W4g1 cylinder. The cross section of the cylinder obtained is as shown in the mi diagram.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to FIG. 1st
The figure is a cross-sectional view showing off the thickness of the metal thin film layer.

In FIG. 1, the material of the ceramic liner 1 is alumina, and as will be described later, pure copper is coated on its outer circumferential surface by thermal spraying and then smoothed by cylindrical grinding. I2 is formed. And this metal thin film layer 2 has a notch! 4 has 16 threads machined in the axial direction.

The material of the steel cylinder 3 is chromium-molybdenum steel,
The inner surface is honed and has a ceramic liner 1.
is shrink-fitted at a shrink-fit ratio of 1/1000.

The ceramic liner 1 is formed by slurry casting and then sintered under normal pressure, and has an inner diameter of 40-1 and an outer diameter of 50-1. After machining it to a length of 800 mm, it is rotated and
Pure copper powder is coated with 1.21 - on the outer circumferential surface by flame spraying.
The surface was ground until a metal thin film layer 2 with a thickness of 1 mm was obtained after cooling.

Further, the chromium-molybdenum steel cylinder 3 has an outer diameter of 1
Using rolled steel material of 50aia+, the inner diameter is 49.95+u
It is honed to +.

Then, this was uniformly heated to 200° C., and the ceramic liner 1 having the metal 115Iffi 2 was inserted into the hole and shrink-fitted.

After this cylinder was subjected to the required processing as a cylinder for a ceramic injection molding machine, it was put into use, but no breakage of the ceramic liner or misalignment with the p* cylinder occurred.

〔Effect of the invention〕

As described above, in the present invention, a soft gold R thin film with a large coefficient of thermal expansion is coated on the outer circumferential surface of a ceramic liner, and notches are provided. It has the effect of expanding in the radial direction of the up cylinder, and prevents breakage of the liner due to shrink fit and relaxation of shrink fit stress caused by cylinder heating.

Therefore, the composite cylinder is extremely stable both mechanically and thermally, without liner displacement or liner destruction due to internal pressure during use, and has significantly improved durability and reliability. It has the effect of making things happen.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a ceramic-metal composite cylinder showing an embodiment of the present invention. 1: Ceramic liner, 2: Metal thin film layer, 3
: W4 cylinder, 4 : Notch agent Patent attorney Takashi Honma Figure 7

Claims (1)

[Claims] 1. A composite of ceramics and metal, characterized in that a thin metal film having a notch in the liner axial direction is coated on the outer peripheral surface of a ceramic liner, and the ceramic liner is attached to the inner surface of a steel cylinder by shrink fitting. Cylinder.