JPH0324432B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a friction welding method when one or both of the materials are ceramics.

[Conventional technology]

In recent years, ceramics have attracted attention as materials with excellent heat resistance, corrosion resistance, and wear resistance.
Molding complex shapes and large parts is difficult, and the establishment of bonding technology is awaited as a solution to these problems.

Conventionally, there have been many research reports and practical examples regarding friction welding of metal materials, but ceramics, which are brittle materials, have problems such as being easily cracked during chucking and being easily cracked by thermal stress, so it has not been put to practical use. has not been standardized.

[Problem to be solved by the invention]

An object of the present invention is to make friction welding, which has high joint strength, work efficiency, and energy efficiency, applicable to joining ceramic materials.

[Means and actions to solve the problem]

In order to achieve the above object, the present invention is characterized in that, as a pre-process, a ductile metal pipe is caulked to the outer peripheral surface of a ceramic cylinder.

To explain the present invention in detail based on the drawings, a pipe 2 made of a ductile metal material is attached to the cylindrical outer peripheral surface of the ceramics 1 to be joined by caulking.
In this case, in friction welding, the material must have a circular cross section such as a round bar or pipe, so the ceramic 1 is a round bar or pipe, and the pipe 2 is made of thin walled material such as aluminum, copper, or nickel. It's a tube.

If the ceramic 1 is directly gripped with a chuck, it often breaks due to stress concentration, and if the gripping force is reduced to prevent it from cracking, it will not be able to withstand the torque during pressure welding and will spin idly.

In the present invention, the pipe 2 made of a ductile metal material is attached to the ceramic 1 by caulking, so that the stress concentration during chuck is alleviated by the pipe 2, and the ceramic 1 can be gripped sufficiently without being destroyed. Further, since metals generally have better thermal conductivity than ceramics, the pipe 2 assists in heat conduction in the axial direction of the ceramics 1 and serves to prevent the ceramics 1 from breaking due to thermal stress.

Further, as shown in FIG. 4, the ceramic 1 to which the pipe 2 is attached and the metal round bar 4 can be friction-welded.

Note that when an insert 3 made of a ductile metal material is fixed to the joint surface between ceramics and ceramics or metal, the ductility of the insert 3 prevents cracking of the ceramic 1, and also relieves thermal stress on the joint surface and increases the joint strength. can be done (first
(see figure).

After joining, the pipe 2 can be removed by cutting or the like, but it can also be left in place and used effectively as a buffer material that can withstand external stress.

〔Example〕

A round bar of 95% alumina ceramics (hereinafter referred to as ``alumina'') with an outer diameter of φ16.3 x 50 mm and a pipe material with an outer diameter of φ16.3 x inner diameter of φ5 x length of 50 mm were used as the material to be welded. Insert 3 is a thin plate of pure aluminum (JIS-A-1050) with an outer diameter of φ16.4 x 2 mm for pressure welding of round bar materials, and an outer diameter of φ16.4 x inner diameter of 7 x 2 mm for pipe materials. was inserted into both joint end faces and pressure welding was performed. Note that alumina, which is a brittle material, can be damaged by impact cracking due to the clamping force, rotational force, pressurizing force, etc. and a sudden temperature gradient near the joint if the outer circumference of the sample is strongly tightened directly with a hydraulic chuck. As shown in Figure 1, the outer periphery of the sample is covered with a thin-walled tube made of aluminum, copper, nickel, etc., the alumina sample is inserted into the thin-walled tube, and the alumina is measured using the planetary ball die method. By slightly contracting the outer periphery, a sample was prepared and pressure welded, taking care not to idle against rotational force and pressurizing force.

Figure 5 shows aluminum inserts made of alumina round bars (outer diameter φ16.4 x thickness 2 mm).
into both joint end faces, and the rotation speed is 4000 rpm.
Friction pressure P ₁ 2Kgf/mm ² , upset pressure P ₂ 3Kgf/mm ² ,
This is an example showing the change in the thickness of the aluminum pieces of the joint joined at a pressure welding time t _{1 of} 20 seconds. As seen in FIG. 5, the shape of the aluminum piece is extruded to the outer periphery of the alumina by frictional heat and pressure, and the thickness of the aluminum piece becomes thinner in the center.

Therefore, if the friction time is increased, the thickness will gradually become thinner, and when the welding is completed, the alumina round bars can be welded together. In addition, in an experiment of joining alumina pipe materials, as shown in FIG. 1, there was no aluminum piece near the joint, and the alumina pipe materials were joined together. In addition, to describe the results of a tensile test of a joint between alumina round bars, the rotation speed was 4000 rpm, the friction pressure P ₁ 2 Kgf/mm ² , the upset pressure P ₂ 3 Kgf/mm ² , and the welding time t ₁ 15 to 20 seconds. The joint welded under the following conditions has a tensile strength σ〓: 8Kgf/
mm ² or more, the fracture occurred at the base material of the alumina round bar, indicating that the joint was strong.

〔Effect of the invention〕

The present invention uses a ductile metal pipe caulked to the outer circumferential surface of ceramics to alleviate stress concentration during chucking, and improves axial heat conduction to prevent damage due to thermal stress. Friction welding of ceramics, which are brittle materials, can be performed.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the sample structure, Figure 2 is a cross-sectional view of ceramics joined together, Figure 3 is an electron micrograph showing the joint between ceramics and the ceramic structure around it, and Figure 4 is a metal FIG. 5 is a cross-sectional view of a case where alumina and ceramics are joined together, and a diagram showing changes in the thickness of the joint during friction welding of alumina to each other. 1...Ceramics round bar, 2...Metal pipe, 4...
Metal round bar.

Claims (1)

[Claims] 1. A method for friction welding ceramics and ceramics or metals, which comprises caulking a ductile metal pipe to the cylindrical outer peripheral surface of the ceramics as a pre-process.