JPS6182073A - Compound cylinder of ceramics and metal - Google Patents

Abstract

PURPOSE:To prevent a ceramic made liner from destruction due to a change of temperature in a cylinder when it is used, by providing an air gap between the metallic cylinder and the ceramic made liner and enabling pressurized fluid to be fed into this air gap. CONSTITUTION:A compound cylinder, fitting a ceramic made liner 1 into a metallic cylinder 2, provides an air gap 3 over almost the whole length of the metallic cylinder 2. And this air gap 3 communicates with the outside through a fluid supply hole 4. Next the compound cylinder is enabled to force pressurized fluid, fed from a pressure fluid unit, to be supplied by pressure into the air gap 3 through a hose 5.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is a composite cylinder in which a ceramic liner is attached to the inner surface of a metal cylinder whose inner surface is required to have wear resistance and corrosion resistance, such as a plastic cylinder. The present invention relates to an improvement of a composite cylinder equipped in an injection/extrusion molding machine for magnetic powder and metal powder used in ceramics, 7-elite, or rare earth magnets.

[1 Jumei technology] In general, this type of cylinder suffers from wear due to friction when the material to be molded is transferred through the cylinder by a screw or plunger built into the cylinder, and from heat generated by organic matter added with the material. Substances generated by decomposition cause corrosion.

Therefore, as cylinders for injection/extrusion molding machines, the inner surface of metal cylinders is coated with alumina, carbide, and nitrogen, which have excellent wear resistance and corrosion resistance.

Composite cylinders equipped with ceramic liners such as silicon oxide and norconia came into use.

However, as shown in FIG. 3, in order to protect the inner ceramic liner 1, which is weak against tensile stress, with the outer metal cylinder 2, the conventional composite cylinder is installed by shrink fitting or press fitting, and the ceramic liner 1 is attached by shrink fitting or press fitting. The liner is composited in a state where compressive stress (hereinafter referred to as preload) is generated.

[Problems that δ Ming attempts to solve]

In conventional composite cylinders, when the temperature rises during use, the thermal expansion coefficient of ceramics is smaller than that of metals, so the interference becomes smaller and the preload becomes lower, causing the gap between the ceramic liner and the metal cylinder to decrease. In some cases, gaps may appear between the lines, which can cause the ceramic liner to break during use.

Therefore, there is a very troublesome problem in that the setting of the interference during shrink fitting or press fitting and the selection of the ceramic material are subject to various restrictions depending on conditions such as temperature and internal pressure when the cylinder is used.

In addition, in the case of shrink fit or press fit, if the machining accuracy of the joint surface between the ceramic liner and the metal cylinder is poor, the joint is uneven, or the interference is large, and the preload generated on the ceramic liner is too large. The ceramic liner may be destroyed during the composite process.

Therefore, the outer surface of the ceramic liner and the metal! ! The inner circumferential surface of the ring requires highly accurate machining, and this machining requires a large number of man-hours, and it is extremely difficult to ensure accuracy in the axial direction for long items.

The present invention aims to solve these problems.

[Means for solving problems]

In the composite cylinder of the present invention, a gap is provided between the metal cylinder and the ceramic liner attached to the inner surface thereof, and pressurized fluid can be introduced into the gap via, for example, a fluid pressure unit. This is what I did.

[For production]

The pressure of the fluid introduced into the gap between the metal cylinder and the ceramic liner can be kept constant at all times by controlling an externally provided fluid pressure unit, for example. In other words, the preload of the ceramic liner can be maintained at a predetermined pressure at all times.

Therefore, no matter how the gap between the joint surfaces of the metal liner and the ceramic liner changes due to changes in temperature when the cylinder is used, the stress caused by the internal pressure generated within the ceramic liner is always suppressed. Because it can be transmitted smoothly and evenly to the outer metal cylinder,
The ceramic liner will not be destroyed when the cylinder is used.

Furthermore, even if the machining accuracy is poor and the joining is uneven, the same effect as described above can be achieved by feeding pressurized fluid into the gap.

〔Example〕

FIG. 1 is a sectional view showing one embodiment of the present invention, in which a ceramic liner 1 is fitted into a metal cylinder 2, an empty PJ 3 is provided over almost the entire length of the metal cylinder 2, and this air gap 3 is connected to the outside. are communicated through a fluid supply hole 4, so that pressurized fluid sent from a fluid pressure unit (not shown) via a hose 5 can be pressurized into the air F]3. 6 is a seal ring.

FIG. 2 is a sectional view showing another embodiment of the present invention, in which a gap 3 is provided in a part in the axial direction where fractures and the like are particularly common in order to generate a constant preload.

〔Effect of the invention〕

According to the present invention, a predetermined preload can always be generated in the ceramic liner, so there is no limitation on the material due to the coefficient of thermal expansion between ceramic and metal.
Further, the outer circumferential surface of the ceramic liner and the inner circumferential surface of the metal cylinder do not need to be processed with high precision, so that the composite cylinder can be manufactured easily and at low cost.

Furthermore, since the ceramic liner does not break during use, the life of the composite cylinder is extended and work efficiency is significantly improved.

As described above, the present invention has many effects.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing one embodiment of the present invention, (&) is a front sectional view, (l+) is a cross-sectional view 1--A of (1), and Fig. 2 is another embodiment of the present invention. Figure 3 shows a conventional composite cylinder; (,) is a front sectional view;
(b) is a side view.

Claims (1)

[Claims] In a ceramic-metal composite cylinder in which a ceramic liner is attached to the inner surface of a metal cylinder, a gap is provided between the metal cylinder and the ceramic liner, and pressurized fluid can be fed into the gap. A composite cylinder made of ceramics and metal, which is characterized by being smoothed.