JPS5886967A - Production of abrasion-resistant composite aluminum member of cylindrical shape - Google Patents

Abstract

PURPOSE:To provide extremely high abrasion resistance on the inside circumferential surface and to maintain machinability on the outside circumferential part by fluidizing the state in solid-liquid coexistence of abrasion resistant powder and an Al alloy in a molding die by the insertion of a plunger die thereby molding the same into a cylindrical shape. CONSTITUTION:An Al alloy and a powdery abrasion-resitant material are agitated at the temp. region in solid-liquid co-existence of the Al alloy, and the half melt thereof is supplied into a molding die 1. Immediately thereafter a plunger die 4 is inserted into the hole 2 of the die 1 and the half melt is molded to a cylindrical shape under pescribed pressure. Thus on account of the effect of the abrasion-resistant dissimilar material existing preferentially on the inside circumferential surface, the part near said inside circumferential surface has extremely high abrasion resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a cylindrical member made of a composite material by adding a wear-resistant substance to an aluminum alloy.

Aluminum alloy (ht) In order to improve the wear resistance to the functional properties of the gold alloy, hard powder or powder consisting of a material exhibiting lubricating properties, such as graphite, is added to the At alloy.
Development is progressing on materials that are composites of powdered foreign substances such as e-SiCe activated carbon, and on methods for manufacturing 2-bar members made of such compositions. Among them, the four-coy casting method, in which the At alloy is heated and stirred in the solid-liquid coexistence temperature range, and the foreign substances are mixed, is used to wet the At alloy and to mix foreign substances with different specific gravities in multiple layers. It has the advantage of being able to be mixed, and is attracting attention in the field of composite materials. According to this compocasting method, all the foreign substances are added to a so-called semi-molten slurry in which primary solid phase particles are suspended, and the foreign substances are mixed while being held in the gaps between the primary crystals. Therefore, it is said that the foreign substances are uniformly dispersed in the At alloy regardless of wettability or specific gravity difference.

However, when viewed locally, the gap between the primary crystals is a liquid phase, so it is difficult to completely disperse the foreign substances, which are difficult to wet with the liquid phase of the At alloy and tend to aggregate, one by one. However, there is a problem that aggregates of foreign substances may remain in the alloy.

The presence of such local aggregates of foreign matter is disadvantageous to the strength characteristics of the material, and also causes problems such as seizure due to foreign matter falling off due to excessive wear. Furthermore, when considering a cylindrical member such as a cylinder lychee, wear resistance is generally required only on the inner peripheral surface, and machinability is rather required on other parts. Therefore, the present inventors focused on the fact that both wear resistance and machinability can be satisfied by unevenly distributing foreign substances only in the parts where wear resistance is required. As a result of molding the semi-shafts in order to make the foreign substances unevenly distributed without agglomeration and to prevent foreign substances from being present in other parts, the semi-molten material was supplied into the mold and a post-press die was inserted. By applying plastic flow to the semi-molten material, the local agglomeration of foreign substances is uniformly dispersed by the flow, and in addition, the semi-molten material is formed into a cylindrical shape. It was discovered that liquid flows preferentially in areas along the line, and as a result, foreign substances are unevenly distributed in these areas.

That is, the present invention was made by paying attention to the conventional problems as described above, and the present invention was made by focusing on the conventional problems as described above.
The solid-liquid coexistence state of the alloy is stirred and supplied to a mold, and a mold is inserted into the mold to form it into a cylindrical shape. At the same time, a part of the molded body along the mold, that is, near the inner circumferential surface, is powdered. The purpose of the present invention is to solve the above-mentioned problems by preferentially distributing wear-resistant substances.

Hereinafter, the present invention will be explained in detail based on Examples.

Example 1 The composition of the At alloy for casting used in this example is shown in the table.

(Heavy tchi) In order to handle the A4 alloy listed in the table in a semi-molten state, the relationship between temperature and solid phase ratio was investigated in advance by thermal analysis and microstructural observation. The results are shown in FIGS. 1 and 2. Next, the temperature at which the solid phase ratio in each alloy becomes 40 to SOS, that is, 560°C for AC8B alloy and 660°C for AC2A alloy, is
A semi-molten slurry was prepared by heating and maintaining the sample at 00° C. while applying mechanical stirring, and a wear-resistant foreign material was mixed into the semi-molten slurry. That is, AC8B alloy is mixed with 5% by weight of Aj, O, (average grain size 3μfT1) and 5-layer 1-chi graphite (average grain size 50-150μm), and AC2A
A semi-molten alloy was prepared by mixing 5 weights of StC (average particle size 70 μm) with 5 weights of activated carbon (average particle size 150 μm).

Next, the semi-molten product was molded using a molding apparatus shown in FIG. In FIG. 3, reference numeral 1 denotes a mold for determining the outer shape of a cylindrical member, which has a cylindrical hole 2 with a diameter of 96-2 and a height of 160 cm widening toward the bottom at the bottom, and an opening 6 at the top. Reference numeral 4 denotes a press die for molding the inner peripheral surface of the cylinder, which is inserted into the hole 2 of the mold 1 through the opening 6, and has a diameter of 74-. The mold 1 and the mold 4 are preheated to 400°C for the AC8B system, and to 450°C for the AC2A system, and after supplying the semi-molten material to the mold 1, the mold 4 is
was inserted into the cavity 2 of the mold 1 at a speed of 10 cm/l@-6 strokes and molded into a cylindrical shape under a pressure of 1300 Kf/as''.Then, the two types of cylindrical members 5 obtained were
A test piece was cut from each of the specimens near the inner circumferential surface and near the outer circumferential surface, and the amount of wear was measured using a Chimken wear tester. In addition,
For comparison, the amount of wear of a normal aluminum alloy (AC8B) that does not contain any foreign substances was also measured. The test conditions were to supply lubricating oil at 80℃, press the sample against the mating material (chromium plated FC25 material) with a load of 9.07K4,
A 2 hour wear test was conducted. The results are shown in FIG. In addition, in Fig. 4, I61 is AC8B series, and Ya2 is A
It is C2A type. As is clear from FIG. 4, in the case of the present invention, the inner circumferential surface has significant wear-resistant properties due to the effect of unevenly distributed wear-resistant foreign substances. Recognize.

Example 2 An AC8B alloy having the same composition as in Example 1 was heated at kA, 0.0°C while maintaining the temperature such that the solid phase ratio was 10-, that is, 580°C.
and graphite were added in the same proportions as in Example 1, stirred in a solid-liquid coexistence state, and then fed into the mold 1 (7) to form a cylindrical member 5 under the same conditions as in Example 1.

Next, the obtained cylindrical member 5 was cut horizontally and vertically, and the macrostructure of the cut surface was examined. The results are shown in photographs in FIGS. 5 and 6. As can be seen from these photographs, it can be seen that the wear-resistant foreign material is unevenly distributed along the inner peripheral surface of the cylindrical member 5.

For comparison, let the semi-molten solution cool as it is #! A photograph of the cross section of the solidified tomato block is shown in Fig. 7. According to FIG. 7, At
, O, and graphite are mixed uniformly,
Localized powder agglomerations remain.

On the other hand, in the case of the cylindrical member 5 manufactured by the method of the present invention shown in FIGS. 5 and 6, there is no agglomeration of foreign substances. Figure 8 (1) (b) is a scanning electron microscopic photograph showing the microstructure. Photo of the area near the surface* (1) (the left side of Fig. 8 (a) is the inner circumferential surface side) and photo of the outer circumference (b) (the right side of Fig. 8 (b) is the outer circumferential surface side) By comparing At and Os near the inner peripheral surface.
JP 11a 58-8 shows that graphite is densely distributed.
69fi7 (3) I understand.

Example 3 Using the A CZ A alloy with the same composition as in Example 1, check the temperature at which the solid phase ratio becomes 20 cm from Figure 2, and while maintaining it at that temperature, add SIC and activated carbon in the same proportions as in Example 1. The cylindrical member 5 was manufactured in the same manner as in Example 1. Samples were cut from the vicinity of the inner peripheral surface and the outer peripheral portion of the manufactured cylindrical member 5, and the structure was examined using a g-microscope. The results are shown in FIGS. 9(a) and 9(b).

Note that the left side of FIG. 9(a) is the inner peripheral surface side, and the left side of FIG.
The right side of b) is the outer peripheral surface side. As is clear from FIG. 9, there are many foreign substances in the vicinity of the inner peripheral surface, and it can be seen that they are dispersed without agglomeration. On the other hand, it can be seen that although foreign substances are not aggregated in the outer peripheral area, t is small. The large black part in the photo is activated carbon, and the white part is aluminum.

In the present invention, the reason why a large amount of foreign substances is selectively or preferentially localized on the inner circumferential surface is considered to be due to the following reason.

That is, when the press mold 4 is inserted into the semi-molten material injected into the bottom part of the cavity 2 of the mold 1, a part of the semi-molten material moves to the upper space of the cavity 2, and the cavity The cavity between the hole 2 and the mold 4 is now completely filled with semi-molten material. By the way, semi-molten solid, ie, primary silicon, has large crystal grains and collides with other crystal grains, making it difficult to move. On the other hand, since foreign substances are fine powders, they act together with liquids. Therefore, when the press die 4 descends,
A liquid portion with high fluidity flows through the gaps between the primary crystals around the mold 4, and foreign substances also gather around the mold 4 along with the flow of the liquid portion. This flow prevents foreign substances from coagulating. 1+, corner A of the tip of the mold 4 (third
(see figure), the semi-molten material is subjected to the heaviest shearing, and as the mold 4 descends, the liquid flows preferentially around the mold 4, accompanied by the foreign material, and as a result, the foreign material becomes cylindrical. Many of these particles are unevenly distributed near the inner circumferential surface of the shaped member 5.

In the above embodiments, the molding is performed under pressure, but it is not necessarily necessary to apply pressure. However, it is possible to create a denser compact by applying pressure. In addition, the ratio of the solid phase of the At alloy when stirring with the 10 □ foreign material TKT alloy was 10 and 20, and 40 to 50% in the above examples, but as a result of preliminary experiments, it was found that the solid phase The ratio is 5~
Good moldability was shown at a ratio of 50.

Furthermore, although examples have been shown in which the At alloys are AC8B and ACZA, it goes without saying that any material that can obtain a solid-liquid coexistence state at a predetermined temperature can be manufactured by the method of the present invention.

As explained above, according to the present invention, an At alloy and a foreign material powder that imparts wear resistance are stirred at a temperature at which the solid and liquid of the At alloy coexist, and then this semi-molten material is supplied into a mold. However, since the press die was inserted into the mold and the semi-molten material was made to flow within the mold to form a cylinder, a wear-resistant foreign substance was formed near the inner peripheral surface of the cylinder made of At alloy. The cylindrical member according to the present invention has remarkable wear-resistant properties because the wear-resistant foreign substances are uniformly dispersed on the inner circumferential surface without agglomeration. Furthermore, it has excellent properties in that there are few such foreign substances on the outer periphery and machinability is not impaired, and it can be used for cylinder liners and bearings at equal pressure, and its industrial value is great.

[Brief explanation of drawings]

Figures 1 and 2 show casting k used in the embodiment of the present invention.
1 is a graph showing the relationship between temperature and solid fraction of alloy, FIG. 3 is a cross-sectional explanatory diagram showing the structure of the mold and press used in the example of the present invention, and FIG. Graphs showing the results of wear tests, Figures 5 and 6 are macrostructures in the horizontal and vertical directions, respectively, of the cylindrical member manufactured by the method of the present invention (Figure 5 is 1.5x, Figure 6 is 0x).
．． 8x) photograph, Figure 7 is a solidified structure of a semi-solid mixture of At, O, and graphite obtained by stirring AC8B alloy in a solid-liquid coexistence state (2x), Figure 8 (a) (b) ) and Figure 9 (
Xun (b) is a photograph of the microstructure of a cylindrical member manufactured by the method of the present invention (Fig. 8 at 500x, Fig. 9 at 100x);
(a) in each figure shows the inner peripheral side, and (a) in each figure shows the outer peripheral side. DESCRIPTION OF SYMBOLS 1... Molding die, 2... Cylindrical hole, 6... Opening part, 4... Embossing die, 5... Cylindrical member. 18 1982-86967 (4) i,, i3i Meno, Veri-Degree - Figure 5 Figure 6 Figure 7 Procedural amendment (voluntary) January 7, 1986 Haruki Shimada, Commissioner of the Patent Office 1. ! 41: Display of the matter 1986 Relationship with the case of Patent Application No. 184388 Applicant: 'l,''tf:, 7. Agent No. 1, 2-46 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture (Kakuguchi) 6. The number of inventions increased by the amendment 7. Details of the invention subject to the amendment @flA@ 5ift summary column 8, contents of the amendment as shown in the attached sheet 13 Vessel 2.1 1, Mei #111, page 9, No. 5 Correct "silicon" in the row to "α phase (aluminum solid solution)". Patent attorney Toyori Oshio

Claims (1)

[Claims] (1) Stirring an aluminum alloy and a powdered wear-resistant substance in the solid-liquid coexistence temperature range of the aluminum alloy, then supplying this semi-molten material into a mold, and inserting a press into the mold. Forming the semi-molten material into a cylindrical shape by
A method for manufacturing a wear-resistant cylindrical aluminum composite member, characterized by: