JPH09136136A - Manufacture of composite body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the manufacture cost of a parts to be manufactured by providing a build-up layer on a surface of a base material. SOLUTION: A lower drum 1 is manufactured by forming a build-up layer 12 on the surface of a base material 11 consisting of Al alloy of excellent workability, and achieving the die forging. The die forging is achieved by a forging die set to generate the deformation associated with the material flow in the direction parallel to the bonding interface before the forming between the base material 11 and the cladding-by-welding layer 12 in the vicinity of the bonding interface so that the area of the bonding interface of the cladding- by-welding layer 12 with the base material 11. The working is facilitated thereby, the bonding strength of the base material 11 with the build-up layer 12 is improved, and the lower drum 1 excellent in the wear resistance can be manufactured at low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite body applicable to the manufacture of parts such as VTR drums, brake disc rotors, engine pistons, etc., whose surface is required to have characteristics such as wear resistance, corrosion resistance and heat resistance. It relates to a manufacturing method.

[0002]

2. Description of the Related Art Video tape recorders (VTRs) include:
Aluminum alloys such as JIS standard A2218 forgings and AC
A lower drum and an upper drum made of 8C casting material are vertically assembled and assembled. Of these drums, especially the lower drum is strongly required to have wear resistance on the outer peripheral surface with which the magnetic tape is in sliding contact. So, for the lower drum,
In order to improve its wear resistance, instead of the above material, for example Al
It is also becoming manufactured with -20 to 30% Si.

In this case, for example, as shown in FIG.
Using an extruded round bar 31 formed from Al-20 to 30% Si powder material as a raw material, a blank 32 having a predetermined length is produced by cutting the extruded round bar 31, and is then carved from the blank 32 to a predetermined length. The lower drum 33 having a shape can be manufactured. However, the above-mentioned materials have high hardness and are hard to cut, so that the blades are heavily worn. As a result, sufficient productivity cannot be obtained by the above-mentioned manufacturing method, resulting in high processing cost.

On the other hand, FIG. 1 (b) shows a method for manufacturing the lower drum by forging. That is, as in the above, Al-20
An extruded round bar 41 of ˜30% Si is used as a raw material and cut into a disc-shaped blank 42. Then, hot forging is repeated to sequentially form the primary molded body 43 and the secondary molded body 44 into a near net shape, and finally, finish processing such as cutting is performed to form the lower drum 45. However, even in this case, since the above-mentioned materials have poor workability, it is necessary to repeat hot forging several times, which results in a high processing cost.

By the way, for example, Japanese Patent Application Laid-Open No. 49-38839 discloses a method of manufacturing an engine piston by providing a special material layer on the surface of a base material. In that method, as shown in FIG.
As shown in (a), first, the head surface of a cylindrical base material 51 made of an aluminum alloy is sprayed with an aluminum oxide or the like to form a built-up layer 52, and then, in FIG. As shown, the built-up layer 52 is applied to the bottom of the forging die 53 to apply the base material 51 to this die.
After being housed in 53, the base material 51 is formed into a predetermined shape by closed die forging as shown in FIG. At this time, a high pressure acts on the overlay layer 52 in a direction of compressing the overlay layer 52, whereby the overlay layer 52 is compressed. As a result, the density of the built-up layer 52 having a high porosity is improved as it is by thermal spraying.

At the peripheral edge portion where the overlay layer 52 is in close contact with the inner peripheral surface of the forging die 53, it is difficult for the overlay layer 52 to be compressed and deformed due to the frictional force generated between the overlay layer 52 and the die surface. As a result, although the bonding interface between the overlay layer 52 and the base material 51 is slightly changed at the peripheral portion thereof, in this case, the shape of the bonding interface is almost unchanged before and after the forging process. Is being done.

The molded product 54 (FIG. 2 (d)) obtained by die forging as described above is subjected to finishing processing, and FIG.
A piston part 55 as shown in is manufactured. Therefore, also in the manufacturing of the lower drum described above, in order to reduce the processing cost as well as the overall material cost, similarly to the above, for example, the JIS standard excellent in machinability as a base material is used.
It is conceivable that a forged material such as A2218 is used, and the outer peripheral surface thereof is coated with a special material such as Al-20 to 30% Si having excellent wear resistance by thermal spraying or the like to produce a composite.

[0008]

However, if the method described in the above publication is applied as it is to the production of the lower drum, there is a problem that sufficient bonding strength cannot be obtained especially between the substrate and the overlay layer. Occurs. That is, in the method described in the above publication, the blank shape and the die shape are set in the overlay layer 52 at the time of forging so that basically only the compressive deformation due to the disappearance of the internal pores due to the compressive force occurs. The joint interface between the material 51 and the overlay layer 52 is almost unchanged before and after forging. Therefore, in manufacturing the lower drum, for example, even if the above-mentioned Al-20-30% Si build-up layer is formed on the outer peripheral surface of the base material made of JIS standard A2218 described above, and the above forging is performed, The surface layer of the base material, particularly the surface oxide film of the aluminum alloy, remains as it is with the buildup layer. For this reason,
No metallurgical joining state can be obtained between the substrate and the overlay, and as a result, sufficient joining strength cannot be secured. As a result, problems such as peeling of the build-up layer are likely to occur when the build-up layer is subjected to finishing processing after forging, and the product yield is reduced, so that the product cost cannot be sufficiently reduced.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for producing a composite body which can reduce the production cost of a component produced by providing a built-up layer on the surface of a substrate. I am trying.

[0010]

In order to achieve the above object, the method for producing a composite of the present invention comprises the steps of forming a built-up layer made of a material different from the base material on the surface of the base material, A method for producing a composite body, in which a base material is molded into a predetermined shape by die forging, wherein a material in a direction substantially parallel to a bonding interface before molding is formed in order to expand the area of the bonding interface between the overlay layer and the base material. It is characterized in that the die forging is performed by providing a forging die set such that the deformation accompanied by the flow occurs in the base material and the overlay layer near the bonding interface.

According to such a manufacturing method, at the time of die forging, a material flow in a direction substantially parallel to the bonding interface occurs in the base material and the overlay layer together with the bonding interface, and the material is deformed.
As a result of expanding the area of the bonding interface between the overlay layer and the base material, the base material or the skin layer of the overlay layer at this bonding interface, particularly,
As described above, when the base material is made of an aluminum alloy, the surface oxide film is divided. Then, at this dividing point, the respective bases of the base material and the built-up layer are directly brought into close contact with each other, whereby atomic diffusion occurs and a metallurgical joining state is obtained. As a result, the bond between the buildup layer and the base material becomes strong, so that peeling of the buildup layer is unlikely to occur during the subsequent finishing process and the like, and the process is facilitated. by this,
It is possible to inexpensively manufacture a composite molded body in which the characteristics due to the material of the overlay layer are surely retained on the surface of the base material.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment in which the present invention is applied to manufacture of a lower drum of a VTR will be described. at first,
The shape of the lower drum 1 will be described with reference to FIG. The lower drum 1 is provided with a cylindrical shaft portion 1a on the central axis, and a collar-shaped portion 1b extending in the radial direction is provided on the outer periphery of the shaft portion 1a at a middle position. The shaft portion 1a is formed with a center through hole 1c through which the center axis of the upper drum 2 described later penetrates, while the lower outer periphery of the collar-shaped portion 1b of the shaft portion 1a is formed in two steps. There is. On the other hand, an outer wall portion 1d extending upward concentrically with the shaft portion 1a is extended from the outer peripheral edge of the collar-shaped portion 1b, and a concave portion 1e opening upward is formed between the outer wall portion 1d and the shaft portion 1a. Has been done. Further, a cutout-shaped opening 1f through which a lead wire for transmitting a signal to a magnetic head or the like provided inside is inserted is formed in a part of the outer wall portion 1d.

The lower drum 1 having such a shape is combined with the upper drum 2 having the same diameter in the vertical direction and incorporated in the video device.
Information is recorded on and reproduced from the magnetic tape 3 in such a manner that the magnetic tape 3 is obliquely wound around the outer peripheral surfaces of the drums 1 and 2 to run. During this information recording / reproduction, the upper drum 2 is rotated at a high speed, whereby an air layer is interposed between the surface of the upper drum 2 and the magnetic tape 3. On the other hand, the lower drum 1 is fixed, and the magnetic tape 3 is
It runs while sliding on the surface of. As a result, wear resistance is particularly required on the outer peripheral surface of the lower drum 1, that is, the outer peripheral surface of the outer wall portion 1d. If the specific dimensions of the lower drum 1 as described above are taken as an example, the outer diameter of the shaft portion 1a is about 20 mm and the length is about 26 mm.
mm, outer diameter of outer wall 1d is about 62 mm, axial length of this outer wall 1d is about
15 mm.

The lower drum 1 having the above-described shape is manufactured as follows in this embodiment. That is, as shown in FIG. 1A, first, an extruded round bar of an aluminum alloy for stamping and forging corresponding to JIS standard A2218 is used as the substrate 11. The diameter of the base material 11 is slightly smaller than the outer diameter of the outer wall portion 1d, for example, about 58 mm. And
As shown in FIG. 2B, Al-30% Si is thermally sprayed over the entire length of the outer peripheral surface of the base material 11 by, for example, a flame spraying method to form a built-up layer 12 having a thickness of about 1 mm.

Next, the plate is successively cut into a plate thickness corresponding to the volume of the lower drum 1, for example, a thickness of about 8 mm, and the same figure (c).
As shown in, a disc-shaped blank 13 for die forging is produced. It is also possible to fabricate a blank 13 similar to the above by first cutting the base material 11 to a predetermined thickness and spraying Al-30% Si on the outer peripheral surface thereof to form the overlay layer 12. Is.

The blank 13 is inserted into the lower die 14 of the forging device, as shown in FIG. The lower mold 14 is formed with a central cavity portion 14a corresponding to the upper side of the shaft portion 1a of the lower drum 1 on the bottom surface, and a peripheral cavity portion 14b corresponding to the outer wall portion 1d at the peripheral portion.
Are formed. Then, as shown in FIG. 2 (e), the lower mold 14 has an upper mold having a lower surface than the collar-shaped portion 1b of the lower drum 1 and a shape corresponding to the central through hole 1c on the lower surface. 15 is inserted from above, and the closed die forging of the blank 13 heated to a predetermined temperature is performed.

At this time, the base material occupying most of the blank 13
Since No. 11 is made of a material having good workability equivalent to JIS standard A2218, it can be formed into a shape substantially similar to the shape of the lower drum 1 by performing only one hot forging as described above. With the plastic deformation of the base material 11 as described above, the region on the peripheral side of the blank 13 is deformed so as to expand in the radial direction until it comes into close contact with the inner peripheral surface of the lower mold 14, and at the same time Side space, that is, the peripheral cavity portion
A material flow such as flowing into 14b fills this space, and thereby the outer wall portion of the lower drum 1
1d is formed. At this time, the build-up layer 12 provided in the outermost layer of the blank 13 also causes a material flow to flow into the peripheral cavity portion 14b, and from the initial shape of the blank 13,
It can be expanded not only in the radial direction but also in the axial direction. As a result, the buildup layer 12 has an initial thickness of about 1 mm of 0.6 to 0.7 mm.
Although the thickness is reduced to some extent, almost the entire outer peripheral surface of the outer wall portion 1d is covered.

As a result of the processing being performed so that such a material flow also occurs in the overlay layer 12, the overlay layer 12 has pores and the like that have been generated inside during spraying disappear, and the density is sufficiently increased. At the same time, the oxide film on the powder surface is also divided. At the same time, at the joint interface between the overlay layer 12 and the base material 11, deformation such that the area thereof is expanded occurs, and as a result, the skin layer of the base material 11 made of an aluminum alloy, particularly the oxide film, is separated.
As a result, a joining surface where the base material 11 and the overlay layer 12 directly contact with each other without intervening an oxide film appears, and the base material passes through this joining surface.
Atomic diffusion between 11 and the overlay 12 easily occurs. As a result, a bonded state in which the overlay layer 12 is firmly bonded to the base material 11 is obtained.

After the die forging as described above is completed, a forged compact 16 as shown in FIG. 6 (f) is taken out of the die, and then,
This molded body 16 is subjected to additional processing and surface finishing of the opening 1f, and as shown in FIG. 6 (e), the outer peripheral surface of the outer wall 1d is made of Al-30% Si having good wear resistance. Is completed as a lower drum 1 having a surface layer composed of As described above, in the present embodiment, the Al-
30% Si is sprayed to form a built-up layer 12, which is forged to form the shape of the lower drum 1. As a result, the use of a special material whose material cost is expensive can be suppressed to a necessary minimum, and most of the processing cost can be reduced by using a material having good workability as the base material 11.
The overall product cost can be made cheaper.

Further, in the above, the overlay layer 12 is formed at the time of forging.
Since the processing of causing plastic deformation in the direction along the bonding interface with the base material 11 is also performed on the portion, the density is improved and the wear resistance is further improved. Moreover, as a result of the joining state between the base material 11 and the overlay layer 12 also becoming strong, for example, excessive machining force is applied to the overlay layer during mechanical finishing after forging.
Even if 12 is added, peeling of the overlay layer 12 is unlikely to occur. As a result, the finishing process is also facilitated, whereby the lower drum 1 having a good shape accuracy can be manufactured at a lower cost.

Next, another embodiment of the present invention will be described with reference to FIG. FIG. 1B shows a disc rotor 21 used for a disc brake. While such a disc rotor 21 is desired to be lightweight, it is used under high temperature, so that the brake sliding surface, that is,
Heat resistance and wear resistance are required for the front and back surfaces of the disk-shaped flange portion 22 that expands in the radial direction.

Therefore, in the present embodiment, similar to the above-described embodiment, for example, a high-strength Al alloy equivalent to JIS standard A2218 or 5000
A round bar of Al-Mg alloy of type No. is used as a raw material, and first, this is cut into a predetermined length to produce a disk-shaped base material 23 as shown in FIG. Then, a material of Al-20 to 40% Si, for example, is thermally sprayed in an annular shape on the front and back surfaces of the base material 23 to form the overlay layer 24. Then, using this as a blank for forging, the die forging similar to the above is performed to form the disc rotor 21 having the shape shown in FIG.

Also in this case, as shown by the broken line arrow in the figure, the blank 23 is formed so that the flange portion 22 is formed by causing the material flow such that the built-up layer 24 expands in the radial direction together with the base material 23. The die forging is performed by defining the shape and the shape of the forging die. As a result, the density of the overlay layer 24 exposed on the front and back surfaces of the flange portion 22 is improved, and the bonding strength with the base material 23 is also strong. As a result, it is lightweight, and the brake sliding surface provided by the overlay layer 24 has heat resistance and
Since the disc rotor 21 has excellent wear resistance and hardly peels off, it can be manufactured as the disc rotor 21 capable of maintaining stable braking performance for a long period of time.

The above embodiments are not intended to limit the present invention, and various modifications can be made within the scope of the present invention. For example, in the above, the build-up layer was formed using a material of Al-20 to 40% Si, but in addition, a wear-resistant / heat-resistant material in which strengthening particles of SiC or Al ₂ O ₃ are dispersed in an Al alloy is used for the meat overlay. It is also possible to form a build-up layer, and further, the present invention can be applied to any combination of the material of the base material and the material of the build-up layer.

Further, in the above, an example in which the overlay layer is formed by flame spraying has been described, but in addition to flame spraying, for example,
Other thermal spraying methods such as HVOF (High Velocity Oxygen Fuel) and plasma spraying can be appropriately selected and used according to the material for forming the overlay. Further, the thickness of the build-up layer at this time can be appropriately set within a range of, for example, about 0.5 to 5 mm.

Further, in addition to the thermal spraying method, the build-up layer can be formed by other methods such as PTA (Plasma Transfered Arc Welding). In addition to the lower drum and the disc rotor described above, the present invention is applied to the manufacture of any component that can improve the surface characteristics by configuring the surface material with a material different from the base material, such as an engine piston. It is possible to

[0027]

As described above, according to the method for producing a composite of the present invention, the molding during die forging after forming the build-up layer on the surface of the base material is performed by forming the build-up layer and the base material. In order to increase the area of the bonding interface, the material flow is performed in the overlay layer together with the base material with the bonding interface interposed therebetween in a direction substantially parallel to the bonding interface. As a result, for example, an oxide film or the like that is present at the bonding interface is divided, and at this dividing position, the bases and the overlaying layers directly adhere to each other to cause atomic diffusion, resulting in a bond. Become stronger. As a result, peeling of the overlay layer is unlikely to occur in the subsequent finishing process, etc., and it becomes possible to manufacture a composite molded body in which the characteristics due to the material of the overlay layer are reliably retained on the substrate surface at a lower cost. .

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a manufacturing process of a VTR lower drum according to an embodiment of the present invention.

FIG. 2 is a partially cutaway front view showing the shape of the lower drum.

3A and 3B show a method for manufacturing a brake disc rotor according to another embodiment of the present invention. FIG. 3A is a perspective view showing a blank shape before die forging, and FIG. 3B is a diagram after die forging. It is sectional drawing which shows a molded shape.

[Fig. 4] Fig. 4 shows an example of a conventional method for manufacturing a VTR lower drum made of a special material. Fig. 4 (a) is an explanatory view of the manufacturing method by shaving, and Fig. 4 (b) is an explanation of the manufacturing method by forging. It is a figure.

FIG. 5 is an explanatory view showing a method for manufacturing an engine piston in a conventional example.

[Explanation of symbols] 11 Base material 12 Overlay layer 13 Blank 14 Lower mold 15 Upper mold

Claims (2)

[Claims] 1. A method for producing a composite body, which comprises forming a built-up layer made of a material different from that of the base material on the surface of the base material, and then forming the base material into a predetermined shape by die forging. In order to increase the area of the bonded interface between the weld layer and the base material, it is set so that deformation with material flow in a direction substantially parallel to the bonded interface before molding occurs in the base material and the weld overlay near the bonded interface. A method for manufacturing a composite body, which comprises providing a forged die and performing die forging. 2. The method for producing a composite according to claim 1, wherein the base material is made of an aluminum alloy.