JPH01262018A - Extruding method for tube stock of metallic radical composite material - Google Patents

Abstract

PURPOSE:To work a tube stock of metallic radical composite material excellent in surface quality by molding matrix metal integrally and arranging it to the side of a die through a stepped mandrel. CONSTITUTION:A stepped part 12a larger in diameter than a central part is provided on the die part at the tip of the mandrel 12, a hollow billet part is molded in layers out of a metallic radical composite material part 15 and a matrix 16 and the matrix part 16 is arranged to the side of the die 3b. First, dead zones 20a, 20b of the mere matrix metal are generated by pressurizing a stem 13 directly in front of the die 3b, and the matrix metal flows out little by little through an outlet of the die 3b and the outlet at the tip part of the mandrel 12 as the hollow billet is deformed and a tube material consisting of a central part made of metallic radical composite material 18 and an internal and an external circumferential surface made of matrix metal parts 19a, 19b can be obtained. Thus, it is possible to work the tube stock of metallic composite material free from surface cracks and excellent in surface quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for extruding a tube material of a metal matrix composite material.

(Prior Art) Metal matrix composite materials can be classified into fiber-reinforced composite materials, two particle-reinforced composite materials, one dispersion-reinforced composite material A, etc., depending on the reinforcing method. Among these, fiber-reinforced composite materials have high specific strength, high specific stiffness, and excellent heat resistance due to the combination of reinforcing fibers and matrix materials, and are used as structural materials for aircraft, etc. is being planned. In addition, particle-reinforced composites (A) are made by combining reinforcing particles and matrix materials.
Materials with excellent heat resistance, abrasion resistance, and corrosion resistance are obtained and are being applied to mechanical parts (particularly sliding parts, etc.).

Although this material has many advantages, it generally has the disadvantages of low deformability and difficulty in plastic working.

In particular, this tendency becomes more pronounced as the volume content of reinforcing fibers and reinforcing particles increases. However, if it were possible to perform plastic processing on this metal matrix composite material, it would be possible to efficiently form it into a predetermined size and shape, and by selecting various plastic processing methods, the orientation of reinforcing fibers, etc. could be controlled. The advantages of metal matrix composite materials can be fully demonstrated. In particular, extrusion processing has a wide range of applications as a plastic processing method applied to metal matrix composite materials, and is an extremely effective processing method as a method for manufacturing pipe materials. That is,
Extrusion pipes of different sizes can be manufactured by exchanging dies, making it suitable for high-mix, low-volume production. In addition, in the production of ring-shaped mechanical components made of metal matrix composite materials,
By cutting the long tube side, it can be manufactured efficiently.

As mentioned above, metal matrix composite tubing can be made with lower cost I.
Although the desire to obtain ... has become extremely high in recent years, there is still no known method for realizing such a desire. That is, a metal matrix composite with a high volume content of reinforcing fibers or reinforcing particles (Vf = 20% or more) is produced by direct extrusion using a mandrel, which is conventionally used as a manufacturing method for high-strength aluminum alloy pipes, etc. The manufacturing method for pipe material has not been established.

Conventionally, methods for extruding brittle materials with low deformability include:
(1) Hydrostatic extrusion method that uses hydrostatic pressure, (2) Ultra-high pressure extrusion method that applies high hydrostatic pressure to the die exit side to prevent cracking, and (3) Extruded billets can be processed by other processing methods. Capsule extrusion methods, in which the material is wrapped in metal and then extruded, are used. However, in these methods, the billet 1~
In order to encapsulate, it requires a lot of pre-processing or for the first time! II. The equipment cost 1- and operating cost of I are higher than those of the direct extrusion method using a mandrel, and the objective of reducing costs has not been achieved.

(Problems to be Solved by the Invention) As mentioned above, metal matrix composites are generally difficult-to-process materials. Taking fiber-reinforced composite materials as an example, as the volume content of reinforcing fibers increases, cracks occur on the surface of the extruded product after extrusion processing. This is due to the tensile stress transferred to the extruded surface during the extrusion process.

That is, metal flow 1 of the direct extrusion method of solid material in Fig. 7
As can be seen in the example above, during extrusion, there is friction between the billet and the wall of container 2! As shown in Fig. 8, the flow velocity distribution of the extruded material 4 at the exit side of the die 3a is caused by the influence of shear interference in the dead zone, friction between the extruded material surface and the die strand, etc. The velocity (Vc) is higher than the surface velocity (Vs) of the extruded material, and the difference in flow velocity (△
V-c Vs) causes tensile stress to act on the surface of the extruded material. In ordinary aluminum materials, surface cracks due to this flow velocity difference are unlikely to occur, but as mentioned above, in the case of metal matrix composite material A, which is a difficult-to-process material, cracks (tearing) occur.
This tends to occur, and especially when the volume content of reinforcing fibers increases, cracking becomes more noticeable.

In extrusion processing of metal matrix composite materials, basic optimal extrusion conditions (e.g.
It is natural to limit the extrusion temperature, extrusion speed, lubrication conditions, die shape, etc.), or metal matrix composite materials have a basic problem of low deformability as a material for extrusion processing. Please keep in mind that (you must

Compared to conventional extrusion methods for brittle materials (such as the above-mentioned hydrostatic extrusion method), metal matrix composite materials can be produced using a simpler method that requires lower initial equipment costs and operational costs. Efficient pipe material extrusion (if possible, 1-1 Tarcos 1 of metal matrix composite material products)
- This leads to a reduction in the amount of carbon dioxide and enables a wider range of applications. In particular, if this extrusion becomes possible using the direct extrusion method using a mandrel, pipe materials made of metal matrix composite materials with a high volume content of reinforcing fibers can be produced at a low cost without changing existing equipment.
It can be obtained with ~. If tubes made of metal matrix composite materials can be easily manufactured using conventional extrusion processing equipment, ring-shaped mechanical components with excellent wear resistance, heat resistance, specific strength, and specific stiffness can be obtained at low cost. , its industrial effects are extremely large.

The purpose of the present invention is to obtain a sound extruded product with no surface cracks, improve the mechanical properties through extrusion processing, and further improve the productivity of extrusion processing and reduce the cost of manufacturing parts and products. An object of the present invention is to provide a method for extruding a tubular material of a base composite material.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a fixed mandrel system in which a pipe material of a metal matrix composite material is produced by a fixed mandrel method of direct extrusion. A stepped part is provided at the tip so that the diameter is larger than the center part,
The method is characterized in that a matrix metal layer is integrally formed, and this matrix metal layer is placed on the die side before extrusion.

(Function) A layer consisting only of matrix metal, which has higher deformability than metal matrix composite materials, is formed on the surface of the extruded product.
The tensile stress exerted on the surface of the extruded material during extrusion is relaxed, resulting in a metal matrix composite tube with crack-free surface quality and excellent mechanical properties.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. The following explanation uses a die half-angle of 90° as an extrusion method.
An example of the direct (forward) extrusion method using the fixed mandrel method and the fixed mandrel method as a method for forming the hollow part of the tube material is shown below. FIG. 1 shows the process of manufacturing a hollow billet for pipe extrusion using an infiltration method (molten metal forging method), which is an example of a method for manufacturing fiber-reinforced composite materials. The infiltration method is a method in which molten metal is infiltrated into reinforcing fibers under pressure. In the present invention, during this pressurized infiltration, in addition to the portion 10 where the matrix molten metal has penetrated between the reinforcing fibers, a portion 11 containing only the molten metal without reinforcing fibers, that is, only the matrix metal, is formed, and then cooled after heat treatment. This is then used as a hollow billet for extruding tube materials. Here, the thickness of the part containing only 71~risk metal is the reinforcing fiber volume, the matrix molten metal volume,
It can be changed by adjusting the pressure during pressurized infiltration, pressurizing stroke, etc.

FIG. 2 shows an example of direct (forward) extrusion using a fixed mandrel method as the next step, which is the method of extruding the tube material. Tube extrusion methods can be categorized by the method of forming the hollow part (inner diameter part), and include hollow die (combined die) methods and mandrel methods, and each of these methods includes direct (forward) extrusion and indirect (tangential) extrusion. - The hollow die method has better dimensional accuracy (particularly thickness unevenness accuracy) than the mandrel method, but it is not suitable for difficult-to-process materials because of the presence of hot crimped parts within the film. As a measure to improve the dimensional accuracy of the mandrel method, accuracy can be improved by thorough management of the extruder core and tools (mandrel, die). For the above reasons, the direct extrusion mandrel method is suitable for extruding metal matrix composite materials. As shown in FIG. 2, the main feature of the present invention is the shape of the mandrel.

That is, the die portion at the tip of the mandrel 12 is provided with a stepped portion 12a that is thicker than the center portion of the mandrel. In addition,
In the figure, reference numeral 13 indicates a stem, and reference numeral 14 indicates a push block. The hollow billet manufactured by the infiltration method shown in FIG. 1 consists of a metal matrix composite material part 15 and a matrix metal part 16, as shown in FIG. Therefore, the matrix metal portion 16 is placed on the die 3b side. Next, the third
As shown in the figure, the die 3b is pressurized by the stem 13.
A tube material 17 of metal matrix composite material is obtained from the outlet of the tube. A cross section of the stationary portion of this tube material 17 is shown in FIG. That is, tube material 1
The central part of 7 is a metal matrix composite material part 18, and the outer peripheral surface and inner diameter surface are matrix metal parts 19a and 19b, respectively.
It becomes. Hereinafter, the reason why the cross section of the extruded material has the structure shown in FIG. 4 by the tube material extrusion method according to the present invention will be explained.

As shown in FIG. 3 during extrusion deformation, two dead zones 20a are formed in the outer circumference and the mandrel immediately before the die 3b.
20b occurs. These dead zones 20a, 2
As described above, the matrix 0b does not contain reinforcing fibers, and since the matrix metal part 4 is arranged on the die 3b side, it is formed only of the matrix metal.

The dead zones 20a and 20b formed in this way are formed during the extrusion deformation process (in the extrusion deformation process, the hollow billet is not a completely rigid body but is deformed by the pressure applied by the stem 13, and the dead zones 20a and 20b are formed from the exit of the die 3b and the exit of the tip of the mandrel 12. It flows out little by little, resulting in a cross section as shown in Figure 4.

In extrusion processing of materials with low deformability, cracks are most likely to occur at the surface of the extruded material. The cause of this is the tensile stress caused by the difference in flow velocity between the central part and the surface layer of the extruded material 4, as shown in FIG. Therefore, in order to prevent surface cracking of the extruded material H, which has low deformability, it is necessary to reduce this tensile stress (i.e., reduce the flow velocity difference between the central part of the extruded material 4 and the surface layer), or increase it. There is a method to alleviate the tensile stress on the extruded product part of the metal matrix composite material by placing a deformable material on the surface layer where large tensile stress is applied. The present invention uses the latter method to form a matrix metal layer on the outer circumferential surface and inner surface of the tube, thereby obtaining a sound metal matrix composite tube with no surface cracks. Another method of disposing a highly deformable material on the outer periphery of an extruded material is as follows: (1) As shown in Fig. 5, ring-shaped metals 21a and 21b that are easy to process are separately manufactured, and the metal matrix composite material is A method for obtaining a combined borrow billet 23 by inserting it into a borrow billet I~ 22 and extruding it, (2) As shown in FIG. Possible methods include immersing the billet in a liquid, cooling it, attaching a number of easily processable metals to the outer periphery of the billet, and extruding the billet to obtain a combined hollow billet 24.

These methods require an additional step in the manufacturing process, but in the present invention, the part that provides the above effect is manufactured during infiltration during the extrusion hollow billet manufacturing process, so extrusion can be performed without the need for a new process. This makes it possible to manufacture hollow billets for use.

Although the infiltration method has been described above as a method for producing hollow billets, a powder method (a method in which metal powder and reinforcing fibers or reinforcing particles are mixed, heated and pressurized, and sintered) is also possible. That is, by adding matrix material powder 71 to a mixture of matrix material powder and reinforcing particles, pressurizing it, and heating it in a heating furnace, extrusion billet 1 to which provides the effects of the present invention is obtained.

[Effects of the Invention] Since the present invention is configured as described above, a pipe material of a metal matrix composite material, which is a difficult-to-process material, can be extruded using a normal extrusion method without using a special method such as using hydrostatic pressure. According to
It is possible to obtain extruded pipe products with excellent surface quality and no surface cracks.

Furthermore, in the case of fiber-reinforced composite materials, mechanical strength can be improved by orienting the fibers in the extrusion direction as a result of extrusion processing. Furthermore, in the manufacturing process, the above effects can be obtained without adding any new steps, and production efficiency can be improved.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing a configuration for producing a hollow billet related to the present invention by an infiltration method, and Fig. 2 is a case in which the hollow billet according to the production method shown in Fig. 1 is directly (forward) extruded by a fixed mandrel method. FIG. 3 is an explanatory diagram showing the state before extrusion, FIG. 3 is an explanatory diagram showing the state during extrusion processing from the state shown in FIG. 2, and FIG. A top view, Figure 5 is an explanatory diagram showing a method different from the method shown in Figure 1, in which easy-to-process metal is placed on each part of the outer and inner peripheries of a tubular extruded material, and Figure 6 shows the outer periphery of a tubular extruded material. , An explanatory diagram showing a method different from the method shown in Figures 1 and 5, in which metal that is easy to process is placed on each part of the inner periphery. Figure 7 is a conventional direct (front) extrusion process of metal from a solid material. FIG. 8 is an explanatory diagram showing the flow, and FIG. 8 is an explanatory diagram showing the difference in flow velocity between the central part and the outer peripheral part of the extruded material in the extrusion processing method. 3b...Dice 10...Part 11 where molten metal of the matrix penetrates between the reinforcing fibers...Part 15 of the matrix where only molten metal exists...
Metal matrix composite material portion 16 of hollow billet 1~ Matrix metal portion 17 to hollow billet 1...Metal matrix composite material pipe material (8733) Agent Patent attorney Yoshiaki Inomata (et al.)
1 person) Karo Chii ■Hi9kuchi Figure 2 ↓ Saito Shi Rikiji Figure 5 Figure 6

Claims (1)

[Claims] In the method for extruding a metal matrix composite pipe material by extruding a metal matrix composite material hollow billet through a die and a mandrel, in the manufacturing process of the metal matrix composite material hollow billet, the tip of the mandrel has a central part. A tube material of a metal matrix composite material, characterized in that a stepped portion is provided so that the diameter becomes larger, a matrix metal layer is formed in one piece, and this matrix layer is arranged so as to be on the die side before extrusion. Extrusion processing method.