JPH02194107A - Manufacture of combined alloy cylinder - Google Patents

Abstract

PURPOSE:To prevent damage of crack, etc., without adding the special complicate process by developing compressive residual stress so as to cancel tensile stress caused by inner pressure in a cylinder during using in corrosion resistant and wear resistant alloy layer on the inner face of the cylinder. CONSTITUTION:Before inserting a steel-made core 2 into the cylinder base material 1, Ti or Ti alloy film layer having the suitable thickness is formed on the outer face of the core 2, or Ti or Ti alloy foil having the suitable thickness is wound and fixed on the outer face of the core 2. Successively, brittle layer 7 of Ti-Fe intermetallic compound, formed by reacting Fe and Ti in the core 2 with HIP treatment, is formed at between the outer face of the core and the lining alloy layer 8. After completing the HIP treatment, at the time of removing the core 2 by cutting both ends of the cylinder base material 1 with machining work, the detachment between the lining alloy layer and the core 2 is made to good with the brittle layer 7, and the lining alloy layer 8 is made to the remaining condition of the compressed residual stress to circular direction without developing any crack. The tensile stress loaded to the cylinder body at the time of operating at high temp. and high inner pressure is reduced with the compressive residual stress in the alloy layer 8.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a composite alloy cylinder that is subjected to large internal pressure during use and a method for manufacturing the same, and in particular to a pie metallic cylinder used in a plastic injection molding machine or an extrusion molding machine and its manufacturing method. Regarding the manufacturing method.

(Prior art) In injection molding machines and extrusion molding machines for plastics,
Composite alloy cylinders with corrosion-resistant and wear-resistant linings on the inner surface of the cylinders have traditionally been used. Conventionally, the method for manufacturing this type of composite alloy cylinder is to sinter corrosion-resistant and wear-resistant alloy powder onto the inner surface of the cylinder base material by hot isostatic pressing (so-called HIP treatment). , this method holds the above-mentioned lining alloy powder inside the cylinder base material by a solid or hollow core, and after the lining alloy powder is sintered and bonded by the HIP treatment, the core is removed, As a result, an injection cylinder having a corrosion-resistant and wear-resistant lining is obtained. In order to prevent cracking and peeling of the lining layer and to increase the strength of the cylinder base material, the cylinder base material is made of a metal material that can be strengthened by heat treatment, and alloy powder is used as the base material of the lining layer. is made of a metal material that has corrosion resistance and has the same heat treatment transformation characteristics and thermal expansion characteristics as the cylinder base material, and the alloy powder is filled into the inner surface of the cylinder base material and subjected to HIP treatment, thereby lining the cylinder. A method has been proposed in which the cylinder base material is heat-treated to further increase its strength (Japanese Patent Laid-Open No. 62-294106).

(Issue 1i1 to be solved by the invention) In injection molding machines and extrusion molding machines for plastics,
In response to recent precision molding, injection and extrusion molding at higher temperatures and pressures are increasingly required, and when the molding machine is in operation, a pressure as high as 2000 kgf/cj may be applied to the inner surface of the cylinder, causing the cylinder to become under internal pressure. There are problems caused by damage. Although the manufacturing method described in JP-A No. 62-294106 mentioned above is somewhat effective in achieving high strength of composite cylinders, it is limited by the materials of the cylinder base material and lining, and also requires heat treatment to increase hardness. There was a problem in that it increased the number of steps and cost.

SUMMARY OF THE INVENTION An object of the present invention is to provide a low-cost composite alloy cylinder that does not require any complicated steps, does not suffer from cracking or other damage, and can withstand high internal pressure during use, and a method for manufacturing the same.

The present invention can also effectively leave compressive residual stress in the circumferential direction in the lining alloy layer on the inner surface of the cylinder base material, and
It is an object of the present invention to provide a method for manufacturing a composite alloy cylinder that can improve peeling between a lining alloy layer and a core during manufacturing by IP processing.

(Means for Solving the Problems) A method for manufacturing a composite alloy cylinder according to the present invention includes inserting a core into a cylinder base material and forming an annular space therebetween;
After filling and sealing the annular space with a corrosion-resistant and wear-resistant alloy powder having a coefficient of thermal expansion smaller than that of the cylinder base material and the core, a HIP treatment is performed to provide corrosion and wear resistance to the inner surface of the cylinder base material. A wear-resistant alloy layer is formed, and an intermetallic compound embrittlement layer is formed between the corrosion-resistant and wear-resistant alloy layer and the outer surface of the core, and after the core is removed, the corrosion-resistant and wear-resistant alloy layer is formed at room temperature and pressure. Compressive residual stress is applied to the alloy layer.

(Example) Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal cross-sectional view of a composite alloy cylinder according to the present invention in a state in the middle of the manufacturing process. First, a solid or hollow core 2 is placed inside the cylinder base material l, which will become the cylinder body, at a distance from the inner circumferential surface of the base material, and the lower ends of the base material l and the core 2 are connected to each other. 1 [Seal by welding etc. according to 3,
Similarly, the upper end of the base material 1 is sealed with an upper lid 5 having a degassing pipe 4. There is a gap between the upper end of the core 2 and the top cover 5 as shown in the figure, and the annular space formed by the cylinder base material l and the core 2 and the gap between the core 2 and the top cover 5 are provided with corrosion-resistant material. After filling with wear-resistant alloy powder 6 and deaerating and sealing, external pressure F is applied to perform HIP treatment. Select mutual materials so that the coefficients (α) are qualitatively large, small, and large. For example, if the cylinder base material l is bearing steel 5UJ-2 and α is 16 x 10-' The lining alloy is a corrosion-resistant and wear-resistant CO or Ni-based self-fluxing alloy with α of 13 x 10-' and an m-core of austenitic stainless steel 5US304, α-20.
The material is X10-"K-'. As a result, compressive residual stress (σ-ku0) remains in the lining alloy layer in the circumferential direction, but at the same time, tensile residual stress (σ-ku0) remains in the radial direction.
σ, > 0), and cracks may occur in the lining alloy layer during cooling after HIP treatment.

Therefore, the present invention involves forming a coating layer of titanium or titanium alloy with an appropriate thickness on the outer surface of the steel core 2 before inserting the steel core 2 into the cylinder base material l, or by using another method. A titanium or titanium alloy foil of an appropriate thickness is wrapped and fixed around the outer surface of the core 2, and the embrittled layer 7 of the Ti-Fe intermetallic compound in which the Fe and Ti of the core 2 have reacted by the above-mentioned HIP treatment is applied to the outer surface of the core. and the lining alloy layer.

After the HIP process is completed, when cutting both ends of the cylinder base material l by machining and removing the core 2, the embrittlement layer 7 is removed.
This improves the peelability between the lining alloy layer and the core 2, and the lining alloy layer does not crack, leaving compressive residual stress in the circumferential direction. FIG. 2 is a longitudinal cross-sectional view of the composite alloy cylinder IO in this state, in which a corrosion-resistant and wear-resistant lining alloy layer 8 with compressive residual stress is fixed to the inner surface of the cylinder 10, which has been finished into a desired shape. ing. In this way, the cylinder 10, in which compressive residual stress in the circumferential direction remains in the lining alloy JiI8, is damaged when the injection molding machine or extrusion molding machine is operated at high temperature (350 to 500°C) and high internal pressure (2000 to 2500 kgf/cj). The tensile stress applied to the cylinder body is canceled out or reduced by the compressive residual stress of the lining alloy layer 8,
Unreasonable force is not generated at the joint between the cylinder body and the lining alloy layer, resulting in increased durability and longer life of the entire cylinder.

(Effects of the Invention) As explained above, according to the present invention, HI using a core
By creating a compressive residual stress in the corrosion-resistant and wear-resistant alloy layer on the inner surface of the cylinder through the simple process of P treatment, which cancels out the tensile stress caused by the cylinder's internal pressure during use, it can be used under high temperature and high pressure conditions. The tensile stress is reduced, and by forming an embrittled layer between the core and the alloy layer, there is no fear of cracking in the post-HIP process, and a highly reliable cylinder can be obtained. Note that the present invention is not limited to cylinders for plastic molding machines, but can be applied to any composite hollow structure that is subjected to high internal pressure.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing a state in the middle of the manufacturing process of a composite alloy cylinder according to an embodiment of the present invention, and FIG. 2 is a vertical cross-sectional view of a composite alloy cylinder obtained by the method of the present invention. 1... Cylinder base material, 2... Core, 3... Lower cover,
4... Degassing pipe, 5... Upper lid, 6... Corrosion and wear resistant alloy powder, 7... Ti-Fe intermetallic compound embrittlement layer, 8... Lining alloy layer, lO...・Composite alloy cylinder. Figure 1 Sub-Agent Patent Attorney Toshikichi Somekawa Figure 2 Nakatsumaai @ Suzume Shirireki Rei Nilede Ordinance 4:1

Claims (3)

[Claims] (1) A core is inserted into the cylinder base material to form an annular space therebetween, and the annular space has a coefficient of thermal expansion smaller than that of the cylinder base material and the core.・After filling and sealing the wear-resistant alloy powder, HIP treatment is performed to form a corrosion-resistant and wear-resistant alloy layer on the inner surface of the cylinder base material, and also to form an intermetallic layer between the corrosion-resistant and wear-resistant alloy layer and the outer surface of the core. A method for manufacturing a composite alloy cylinder, comprising forming a compound embrittlement layer, and after removing the core, compressive residual stress is applied to the corrosion-resistant and wear-resistant alloy layer at room temperature and pressure. (2) After forming a titanium or titanium alloy film layer on the outer surface of the core by thermal spraying, T
2. The method of manufacturing a composite alloy cylinder according to claim 1, further comprising forming an i-Fe intermetallic compound embrittlement layer. (3) A Ti-Fe intermetallic compound embrittlement layer is formed by wrapping and fixing titanium or titanium alloy foil of an arbitrary thickness around the outer surface of the core in advance and by the HIP treatment. A method for manufacturing a composite alloy cylinder according to item 1.