JP2747757B2 - Cylindrical parts with ceramic sleeves - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a cylinder in which the inner surface of a cylindrical part is required to have wear resistance, corrosion resistance, etc., for example, an injection / extrusion molding machine used for molding plastic, ceramics, ferrite or rare earth magnets. The present invention relates to the improvement of cylindrical parts such as cylinders, particularly ceramic composite parts in applications where a cylindrical cylinder made of a ceramic material is fitted into an outer cylinder made of a metallic material and heated and cooled during use. Regarding improvement.

[0002]

2. Description of the Related Art For example, the inner surface of a cylindrical cylinder used in a plastic molding machine or the like is formed of a resin or a hard additive added to the resin when a screw provided in the cylinder slides and rotates in the cylinder. In addition to abrasion and corrosion caused by reinforcing agents such as agents and glass fibers, there is a problem that cylinder components are mixed into the molding material. In response to such problems, a cylinder in which a liner made of ceramics having excellent wear resistance, corrosion resistance, and heat resistance (thermal shock resistance) is mounted on the inner surface of a cylindrical cylinder is being studied. In this case, ceramics have extremely excellent wear resistance and corrosion resistance as compared with metal materials, but have the disadvantage that they are extremely brittle, but as described above, they are applied to the inner surface of a cylinder of a plastic molding machine or the like. For the purpose of preventing the ceramic from being damaged by molding internal pressure during molding, contact with a screw, etc., for example, as disclosed in JP-A-64-53825,
A composite structural part whose outer peripheral portion is reinforced with carbon steel or the like by shrink fitting or the like is used.

[0003]

However, when a ceramic composite cylinder having a structure in which ceramics are held by metal of the outer cylinder by performing shrink fitting or the like in advance as described above is used for a plastic molding machine or the like, the molding (use) temperature is increased. Is 200 ℃ ～ 4
Because of the temperature rise to 00 ° C, the difference in the coefficient of thermal expansion between the outer cylinder made of a metal material and the inner cylinder made of a ceramic material,
There is a problem that a difference in elongation in the axial direction is caused, and a tensile force in the axial direction acts on the inner cylinder due to the frictional force between the contact surfaces of the two to generate cracks in the circumferential direction. Further, the compressive stress applied to the inner cylinder secures a compressive stress with respect to the internal pressure generated in a state of use as a molding machine cylinder and a decrease in the compressive stress due to a difference in thermal expansion coefficient between the outer cylinder and the inner cylinder during heating. Need to add a very large shrink fit. For this reason, when heating and cooling of the ceramic composite cylinder are repeated, seizure may occur on the contact surface between them.
When this seizure occurs, the transmission force in the axial direction becomes extremely large, which causes a problem that cracks occur in the circumferential direction.

[0004] Therefore, as a method for preventing this, conventionally, as one of the methods for reducing the influence of heating and cooling, when selecting an outer cylinder made of a metal material, the coefficient of thermal expansion of the outer cylinder made of a ceramic material is reduced. The coefficient of thermal expansion has been approached.
No. 043, Kovar (main component 2)
8-29% Ni-17-18% Co-Fe alloy), Amber (36-52% Ni-Fe alloy).
Japanese Utility Model Laid-Open No. 4-450 discloses a Ti-based alloy such as T
A low thermal expansion alloy such as an i-6Al-4V alloy is applied. However, any metal material having a low coefficient of thermal expansion equivalent to ceramics that can be applied by this method is difficult to obtain and is expensive, and at the same time, has poor workability compared to carbon steel, etc., and is generally used for industrial applications. Is not suitable.

On the other hand, it is conceivable that the same effect can be obtained by providing a gap in the outer cylinder made of a metal material and cooling it to keep the temperature of the outer cylinder lower than the temperature of the inner cylinder made of the ceramic material. Because of the close contact by shrink fitting, the temperature of the ceramic inner cylinder also decreases, and it becomes difficult to knead each molding material and maintain an appropriate temperature for molding, resulting in insufficient kneading and molding failure. The present invention has been made to solve the above problems and problems, and is a cylindrical part in which an inner layer is made of ceramics and an outer layer part is made of metal, which prevents cracks and the like even when heated and cooled. It is an object of the present invention to provide a ceramic interior cylindrical part that can be manufactured.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a metal cylindrical sleeve.
A cylindrical shape made of ceramic material inside the leave
The composite cylindrical part that shrink-fits and holds the inner cylinder
After hard chrome plating the entire length of the inner surface of the cylindrical sleeve,
Between a metal cylindrical sleeve and a ceramic material inner cylinder
Characterized by lubricating material all over the length of the ceramic
It is in a cylindrical part with a sleeve inside.

[0007]

[Function] The lubricating agent disposed between the outer cylinder made of metal material and the inner cylinder made of ceramic reduces the frictional force between the contact surfaces of the two, lowers the tensile stress generated in the ceramic, and also prevents seizure. It has a great effect.

[0008]

The present invention will be described below in detail with reference to examples. FIG. 1 is a sectional view showing an embodiment of the present invention. FIG.
1A and 1B, the inner cylinder 2 is formed in a hollow cylindrical shape using sialon ceramics. Next, 1 is an outer cylinder,
The inner cylinder 2 is formed in a hollow cylindrical shape having a size and a shape capable of giving an optimal compressive stress, and the inner cylinder 2 is fitted by shrink fitting. In order to maintain the lubrication state in the heating atmosphere sounder, the inner surface of the outer cylinder was previously subjected to hard chrome plating 3 before use. If a soft layer, for example, a copper plating layer is used as the plating layer, the lubricating property is reduced, which is not preferable. At the time of shrink fitting, BN (boron nitride) powder was sprayed onto each of the inner peripheral surface of the outer cylinder 1 and the outer peripheral surface of the inner cylinder 2 before heating the outer cylinder 1 to form a lubricating layer 4 on the surface. After construction. The shrink-fitting ratio when used as a cylinder material is determined by using a tightening margin necessary to add a compressive stress that can withstand the operating temperature and operating pressure of the molding machine. In addition, since ceramics have the disadvantage of being brittle against impact, when used as a cylinder for molding machines, chamfering was applied to the inner corners of both ends where the impact was most likely to be impacted by the contact of the sliding and rotating screw. It was taken.

Table 1 shows the results of heating and cooling tests of various types of extruder cylinders manufactured as described above. The heating temperature was 250 ° C. for alumina and 300 ° C. for Sialon, and heating and cooling were repeated at least 10 times or more. As is clear from Table 1, it was confirmed that the product of the present invention exerts a great effect in preventing circumferential cracks which occurred in the conventional cylinder fitted and manufactured without performing lubrication treatment. .

[0010]

[Table 1]

Further, the ceramic inner diameter φ90 in Table 1
As a result of mounting a Sialon cylinder on the extruder shown in FIG. 2 and performing a molding test at a molding temperature of 250 to 300 ° C.,
In addition to preventing circumferential cracks at the time of heating that occurred in the cylinder when fitted and manufactured without performing lubrication treatment, and particularly when molded at a high temperature, the cylinder is heated to the heated ceramic interior cylinder 7 at room temperature. It was confirmed that there was no crack due to a temperature gradient (thermal shock) generated in the ceramic inner cylinder 2 when the screw 8 was inserted. In addition, the chamfered corners of the ceramic insert and insert
Collision between the rotating screw 8 and the inner surface corner of the ceramic was prevented, and it was confirmed that chipping of the end surface corner did not occur at all. When this ceramic interior cylindrical part is applied, for example, as a cylinder for a plastic molding machine, it is desirable to chamfer 0.1 to 1.0 mm to the corner of the ceramic end face in order to prevent chipping of the corner. 2, reference numeral 5 denotes a hopper, 6 denotes a hopper opening cylinder, 9 denotes a band heater, and 10 denotes a die.

Although the embodiments of the present invention have been described above, the material constituting the ceramic interior cylindrical part is as follows.
The ceramic liner is made of ceramic material such as alumina, silicon carbide, silicon nitride, and sialon, which has wear resistance, corrosion resistance, and heat resistance (thermal shock resistance). The steel outer cylinder is made of carbon steel, chromium-molybdenum steel, etc. Use steel. In particular, when the ceramic liner is used in a high temperature region exceeding 300 ° C., it is desirable to apply silicon nitride and sialon having higher thermal shock resistance. Materials used for forming the lubricating layer include lubricating materials capable of maintaining a lubricating effect at a working temperature required for fitting the inner and outer layers, such as a shrink fitting working temperature and a use temperature as a cylinder, for example, boron nitride, graphite, and the like. And molybdenum disulfide are preferred. As shown in FIG. 3, a spiral groove 11 having a depth of about 10 μm is formed on the inner peripheral surface of the metallic material outer cylinder 1 in order to hold the lubricant on the contact surface between the outer cylinder and the inner cylinder. It is desirable to provide a circumferential groove 12 near the end face, and also near the end face so that the lubricant does not flow out from both end faces.

[0013]

According to the present invention, the tensile stress in the axial direction at the time of forming (heating) acting on the inner cylinder made of a ceramic material can be made extremely small, and the occurrence of circumferential cracks generated in the inner cylinder can be prevented. can do. Also, an inexpensive material such as carbon steel can be used as the outer cylinder material. As a result, various properties such as wear resistance and corrosion resistance inherent in ceramic materials can be sufficiently exhibited, for example, durability of an extruder sleeve, stabilization of molded product quality,
It can significantly contribute to the improvement of product yield and the like, and has a great effect in that it can be manufactured at low cost by using a metal material such as carbon steel.

[Brief description of the drawings]

FIG. 1 is an exploded sectional view and an enlarged sectional view of a corner showing an embodiment of the present invention;

FIG. 2 is a cross-sectional view of an extruder cylinder used in the test of the embodiment.

FIG. 3 shows an example of groove processing of a metal material outer cylinder for holding a lubricant.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer cylinder 2 Inner cylinder 3 Hard chrome plating 4 Lubricant layer 5 Hopper 6 Hopper port cylinder 7 Ceramic interior cylinder 8 Screw 9 Band heater 10 Die 11 Spiral groove for holding lubricant 12 Peripheral groove for holding lubricant

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI B32B 9/00 B32B 9/00 Z 15/04 15/04 18/00 18/00 (72) Inventor Junichi Yoshiura Kitakyushu, Fukuoka Prefecture 46-59 Nakahara, Tobata-ku Nippon Steel Corporation Machinery & Plant Business Department (56) References JP-A-4-16569 (JP, A) JP-A-61-111981 (JP, A) JP-A-59 −33128 (JP, A) Actually open 62-148701 (JP, U)

Claims (1)

(57) [Claims] 1. A ceramic sleeve inside a metal cylindrical sleeve.
Shrink-fitting and holding the inner cylinder formed of a cylindrical material
For composite cylindrical parts, the total inner length of the metal cylindrical sleeve
After hard chrome plating on the metal cylinder sleeve and ceramic
Lubricants are distributed over the entire length between the inner cylinders of the mixed material.
Cylindrical part with ceramic sleeve inside
Goods.