JPS62116709A - Formation of sintered layer to curved part - Google Patents

Abstract

PURPOSE:To form a wear-resistant sintered layer having no crack defects by allowing the 1st alloy sheet to tightly contact a part of metallic parts where wear resistance is required and subjecting the sheet to preliminary sintering, then covering the cracked part of the preliminarily sintered layer with the 2nd alloy powder sheet and sintering the sheet. CONSTITUTION:The 1st alloy sheet 2 obtd. by kneading 91vol%<=150 mesh powder of the ternary eutectic alloy of Fe-P-C, Fe-Mo-C, Fe-B-C, etc., having high hardness and excellent wear resistance and 9vol% acrylic resin adhesive binder such as acrylate diluted with toluene and rolling the mixture is brought into tight contact with the part 6a such as cam of a metallic cam shaft for automobiles, etc., where the curving is large and such sheet is preliminarily sintered in an H2 atmosphere. The cracks are often generated in such a case; therefore, the 2nd alloy sheet 10 which consists of 97vol%<=200 mesh powder of ferro alloy ocntg. 2.5% P, 4.5% C, and 11% Mo and 3vol% above-mentioned resin binder and generates a liquid phase at the temp. lower than the temp. of the 1st alloy sheet 2 is coated on such cracks and is sintered in the non- oxidizing atmosphere. The cracks aare filled by the liquid phase of the 2nd alloy sheet and the crack-free sintered layer is thus formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for forming a wear-resistant sintered layer on a curved portion of the surface of a metal base material.

(Conventional technology) Conventionally, alloy powder with excellent wear resistance is compressed into a predetermined shape to form a green compact, and this green compact is sintered. Methods of obtaining metal parts are well known. In this way, when obtaining a metal member having a desired shape by sintering a green compact, if the entire metal member is formed by sintering a molded green compact, the manufacturing cost is usually comparatively low. It becomes a big deal. For this reason, instead of forming the entire metal member by sintering a molded green compact, wear-resistant sintering is applied only to the parts of the metal member where wear resistance is particularly required, for example, to the surface of the metal member. Methods of forming layers are also known.

As a method for forming a wear-resistant sintered layer on the surface of such a metal member, for example, as described in JP-A-51-83834, a layer made of a self-fusing alloy powder and a thermoplastic acrylic resin is used. By adhering the sheet to the surface of the metal base material using a binder such as toluene, and then heating and sintering the sheet together with the metal base material in an air atmosphere,
A method has been proposed in which self-fusing alloy powder is fused to the surface of a metal base material. Also, for example, JP-A-59-83704
The publication describes that by forming an alloy powder sheet made of wear-resistant ternary eutectic alloy powder and acrylic resin, and heating and sintering this alloy powder sheet in close contact with the surface of a metal base material, A method has been proposed in which a ternary eutectic alloy powder is melted to fuse an alloy powder sheet to the surface of a metal base material to form a wear-resistant sintered layer.

(Problems to be Solved by the Invention) By the way, when forming a wear-resistant sintered layer on the surface of a metal base material having a curved surface, such as a cam provided on a camshaft of an automobile, the above-mentioned method is used. When a method in which an alloy powder sheet is brought into close contact with the surface of a metal base material and heated and sintered is applied, bending stress is applied to the alloy powder sheet when it is brought into close contact with the surface curve of the metal base material. Therefore, this bending stress becomes considerably large in a portion where the curvature of the surface curved portion of the metal base material is relatively large.

Then, during sintering, the alloy powder sheet closely adhered to the metal base material is hardened by a condensation polymerization reaction accompanying thermal decomposition of the resin used as a binder in the preliminary sintering stage for dewaxing. Although it is forced, like this,
By hardening the alloy powder sheet under a relatively large bending stress, the alloy powder sheet can cope with surface curvatures of the metal base material, especially surface curvatures with relatively large curvatures. There is a risk that cracks may occur in the areas where the When the alloy powder sheet is subjected to main sintering in order to fuse the alloy powder sheet and the metal base material in a state in which cranking has occurred in the alloy powder sheet, the surface of the metal member after sintering will have crack defects. There is a disadvantage that the sintered layer is formed.

In view of this, the present invention involves sintering an alloy powder sheet in close contact with the surface of a metal base material in order to form a wear-resistant sintered layer on the surface of the metal base material having a curved surface. Hits the,
The alloy powder sheet is closely attached to the surface of the metal base material,
Even if cracks occur during preliminary sintering in a curved portion of the surface of the metal base material that corresponds to a relatively large curvature area, the surface curve of the metal member obtained after main sintering may The wear-resistant sintered layer that forms the curved portion can be made free of crack defects.
It is an object of the present invention to provide a method for forming a sintered layer on a curved part.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the method of forming a sintered layer on a curved part according to the present invention includes a wear-resistant joint alloy powder and an acrylic adhesive binder. A first alloy powder sheet consisting of a wear-resistant alloy powder and an acrylic adhesive binder is pre-sintered in a non-oxidizing atmosphere by closely contacting the surface curve of the metal base material. A second alloy powder sheet that is made of
After the pre-sintered first alloy powder sheet is brought into close contact with the portion corresponding to the relatively large surface curvature of the metal base material, the first alloy powder sheet and the second alloy By sintering the powder sheet in a non-oxidizing atmosphere, a wear-resistant sintered layer is obtained on the curved surface of the metal base material.

(Function) According to the method for forming a sintered layer on a curved part according to the present invention, the first alloy powder sheet is brought into close contact with the surface of the curved part of the metal base material, and the non-oxidized After pre-sintering in a neutral atmosphere, a portion corresponding to a relatively large curvature portion of the surface curve of the metal base material is placed on the pre-sintered first alloy powder sheet. A second alloy powder sheet is brought into close contact so as to cover the sheet, and then both the first and second alloy powder sheets are sintered in a non-oxidizing atmosphere to improve the surface of the metal member obtained after sintering. A wear-resistant sintered layer forming a curved portion will be formed.

In this case, as the first alloy powder sheet is hardened by a condensation polymerization reaction accompanying thermal decomposition of the acrylic adhesive binder during preliminary sintering, the curvature at the surface curve of the gold FF1L material Even if a crack occurs in a part that is in close contact with a relatively large area, such a crack
The first alloy powder sheet is brought into close contact with the pre-sintered first alloy powder sheet, covering the crank generation part, and the second alloy powder sheet is sintered at the same time as the main sintering of the first alloy powder sheet. It is occluded by the resulting liquid phase components. the result,
A high-quality wear-resistant sintered layer without crack defects is formed on the curved surface of the metal member obtained after main sintering.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIGS. 1 to 5 show each step in an example of the method for forming a sintered layer on a curved part according to the present invention, and this example shows a camshaft used as a metal base material having a curved surface. It is said that this method has been applied to form a wear-resistant sintered layer on the cam forming part of.

In this example, first, as shown in FIG. 1, 9% by volume of an acrylic resin diluted with toluene and 9% by volume of a wear-resistant eutectic alloy powder are used as an acrylic adhesive binder.
The first alloy powder sheet 2 formed by kneading 1% by volume is brought into close contact with the curved surface of the cam forming part 6 used as the metal base material.

In forming the first alloy powder sheet 2, the acrylic resin may be, for example, a polymer of ecrylic ester or methacrylic ester, or a polymerizable monomer having a functional group copolymerizable with these esters. A copolymer with is used. On the other hand, the wear-resistant eutectic alloy powder that is bonded by the acrylic resin used as the acrylic adhesive binder to form the first alloy powder sheet 2 has a composition in which, for example, phosphorus (P) is .0% by weight.

Carbon (C) is 2. O @ amount%, molybdenum (Mo) is 4.
0 weight%, chromium (Cr) 10.0% by weight, and iron (F
e) is 83.0% by weight, and the powder particle size of each of these components in the first alloy powder sheet 2 is 150 mesh or less.

Such wear-resistant eutectic alloy powders include, for example, Fe-
PC-based, Fe-Mo-C-based, and Fe-B-C-based ternary eutectic alloy powders are used. Then, this ternary eutectic alloy powder has a temperature of 10 to 5
It is desirable that a liquid phase of 0% by volume is formed and that the liquid phase component has good wettability to the metal base material. In addition, chromium (Cr), vanadium (
■), tungsten (W), niobium (Nb).

Some secondary components such as tantalum (Ta) and titanium (Ti) are added. The reason why the powder particle size of each component in the first alloy powder sheet 2 is 150 mesh or less is because the first alloy powder sheet 2 is sintered and a part of the wear-resistant eutectic alloy powder is melted. This is to reduce the number of pores that occur when the pores are exposed. Then, the first alloy powder sheet 2 containing 91% by volume of wear-resistant eutectic alloy powder bound by 9% by volume of acrylic resin is rolled by a roller or the like to a thickness of, for example, 2 mm.

It is approximately 70cm long and 25cm wide.

Next, the first alloy powder sheet 2 brought into close contact with the curved surface of the cam forming part 6 is pre-sintered in a non-oxidizing atmosphere. This preliminary sintering is performed, for example, by heating the first alloy powder sheet 2 in a hydrogen gas atmosphere at a heating rate of about 0°C/min to about 300°C;
℃) for about 60 minutes. In this preliminary sintering, the acrylic resin in the first alloy powder sheet 2 causes a condensation polymerization reaction, thereby improving the adhesion between the first alloy powder sheet 2 and the curved surface of the cam forming part 6. Secured. At this time, the first alloy powder sheet 2 is hardened by the condensation polymerization reaction of the acrylic resin, and the curvature of the surface curved portion of the cam forming portion 6 is increased at a portion 6a where the acting bending stress is increased. As shown in FIG. 2, crank 8 is likely to occur in the portion corresponding to .

Subsequently, as shown in FIG.
The second alloy powder sheet 10 is placed on the portion of the first alloy powder sheet 2 that corresponds to the portion 6a of the surface curved portion of the cam forming portion 6 where the curvature is large. Being held in close contact. This second alloy powder sheet 10 is heated to a lower temperature than the first alloy powder sheet 2, for example, to a temperature that is 50°C or more lower than the first alloy powder sheet 2. For example, 3% by volume of acrylic resin diluted with toluene, which is an acrylic adhesive binder, and 97% by volume of wear-resistant eutectic alloy powder. are kneaded and formed. Such second alloy powder sheet 10
The wear-resistant eutectic alloy powder forming the composition contains, for example, 2.5% by weight of phosphorus, 4.5% by weight of carbon, 11.0% by weight of molybdenum and 82.0% by weight of iron. The powder particle size of each component is approximately 200 mesh or less. Then, the second alloy powder sheet 10 containing 97% by volume of wear-resistant eutectic alloy powder bound by 3% by volume of acrylic resin is rolled by a roller or the like to a thickness of, for example, 1 mm.

It is formed to have a length of 3Qmm and a width of 25mm.

Next, main sintering of the first alloy powder sheet 2 to which the second alloy powder sheet 10 is closely attached as described above is performed in a non-oxidizing atmosphere. In this main sintering, first, the first alloy powder sheet 2 and the second alloy powder sheet 10 are heated to about 1040°C at a temperature increase rate of about 0°C/minute in a hydrogen gas atmosphere, for example. , its temperature (approximately 10
40"C) for 10 minutes. At this time, a part of the wear-resistant eutectic alloy powder in the second alloy powder sheet 10 melts to form a liquid phase, and the liquid phase components , as shown in FIG. 4, the cam forming portion 6 of the first alloy powder sheet 2
If a crack 8 is generated in a portion corresponding to a portion 6a having a large curvature in the surface curved portion, the crack 8 will penetrate into that crank 8 and close it.

Thereafter, the first alloy powder sheet 2 and the second alloy powder sheet 10 are further heated at a heating rate of approximately 0° C./min.
00℃, and at that temperature (approximately 1100℃) 20
After being held for a minute, it is slowly cooled. In such a heating and cooling process, in addition to the wear-resistant eutectic alloy powder in the second alloy powder sheet 10, a part of the wear-resistant eutectic alloy powder in the first alloy powder sheet 2 is melted. It becomes a liquid phase. Then, the liquid phase component increases within the range of 10 to 50% and diffuses along the surface of the cam forming part 6, thereby causing the cam to form as shown by the dashed line in FIG. Part 6
A wear-resistant sintered layer 2° obtained by sintering the first alloy powder sheet 2 and a wear-resistant sintered layer 2° obtained by sintering the second alloy powder sheet 10 on the curved surface of the A stratum 10' is formed. Here, generated in the first alloy powder sheet 2,
If there is a crack 8 in which a part of the wear-resistant eutectic alloy powder in the second alloy powder sheet 10 has melted and the liquid phase component has permeated, the crack 8 is in the second alloy powder sheet 10. 10
will be filled with the sintered body obtained by sintering.

The wear-resistant sintered layers 2'' and 10'' formed on the curved surface of the cam forming portion 6 as described above are then ground to form a structure as shown by the solid line in FIG. Cam 6 provided with a wear-resistant sintered layer forming a curved portion on the surface
' is formed. In such a case, as described above, cracks 8 are generated in the first alloy powder sheet 2 at the portion corresponding to the portion 6a of the surface curved portion of the cam forming portion 6 where the curvature is large during its preliminary sintering. However, the first and second alloy powder sheets 2 and 10 are in a state where such cracks 8 are closed by the liquid phase component generated during sintering of the second alloy powder sheet 10 disposed so as to cover the cracks 8. Since the material is sintered, the wear-resistant sintered layer forming the 6° surface curve of the cam obtained after sintering is of good quality and free of crack defects.

(Effects of the Invention) As is clear from the above explanation, according to the method for forming a sintered layer on a curved part according to the present invention, the sintered layer is brought into close contact with the curved part of the surface of the metal base material and is subjected to preliminary sintering. A second alloy powder sheet that produces a liquid phase component at a lower temperature than that of the first alloy powder sheet in a portion corresponding to a portion where the surface curved portion has a relatively large curvature. After the alloy powder sheets are brought into close contact, main sintering is performed in which the first and second alloy powder sheets are sintered, so even if cracks occur in the first alloy powder sheet as a result of preliminary sintering, , such cracks are closed by the liquid phase component obtained by melting the second alloy powder sheet during the main sintering, and as a result, a curved part is formed on the surface of the metal member obtained after the main sintering. The wear-resistant sintered layer can be made of high quality without crack defects.

[Brief explanation of drawings]

FIG. 1, FIG. 2, FIG. 3, FIG. 4, and FIG. 5 are diagrams used to explain each step of an example of the method for forming a sintered layer on a curved portion according to the present invention. In the figure, 2 is the first alloy powder sheet, 2' and lO' are the wear-resistant sintered layers, 6 is the cam forming part, 6'' is the cam, 8 is the crack, and lO is the second alloy powder sheet. Yes. Patent applicant Mazda Motor Corporation Figure 1

Claims (1)

[Claims] a step of closely adhering a first alloy powder sheet comprising wear-resistant eutectic alloy powder bound by an acrylic adhesive binder to a curved surface of a metal base material; and a step of pre-sintering the first alloy powder sheet in close contact with the first alloy powder sheet in a non-oxidizing atmosphere, and bonding the wear-resistant eutectic alloy powder with an acrylic adhesive binder; A second alloy powder sheet that generates a liquid phase component at a lower temperature than the alloy powder sheet of A method for sintering a curved portion, comprising a step of bringing the first and second alloy powder sheets into close contact with a portion corresponding to a relatively large portion, and a step of sintering the first and second alloy powder sheets in a non-oxidizing atmosphere. How to form strata.