JPH07233490A - Production of aluminum alloy bearing - Google Patents

Abstract

PURPOSE:To lessen the fluctuation in the height of a bearing consisting of an Al alloy and the variation thereof by roughening the surface of a bearing layer and subjecting the surface to a treatment for desmutting with a liquid having a specific compsn., then to an overlay treatment. CONSTITUTION:The surface of the Al alloy bearing layer is roughened by etching to 1 to 10mum Re, by which the adhesion property to a subsequent overlay etching layer is improved at the time of producing the bearing for internal combustion engines by joining a Cu alloy layer which is dispersed with a secondary phase consisting of at least one kind of Sn and Pb and contg. at least one kind among Cr, Si and Cu to the inside surface of a semi-arc-shaped steel backing metal. Next, the surface is treated by smut treating liquid contg. 20 to 80% phosphoric acid, 0.5 to 40% mineral acid, such as nitric acid, exclusive of a chromic acid and hydrofluoric acid, <20% heterocyclic compd., such as pyridine, etc., or <10% urea and <10% metal salt, such as sulfate and nitrate of Cu and Sn. The Al alloy bearing which is smaller in the amt. of decreasing the bearing height by the smut removal and is lessened in the variation thereof is easily produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an aluminum alloy bearing, and more specifically, a semi-finished product in which an aluminum bearing alloy layer is joined to the inner surface of a semi-circular arc-shaped back metal, The present invention relates to an improved method for producing an aluminum alloy bearing in which a semi-finished product is brought into contact with an etching solution to roughen the surface of an aluminum bearing alloy layer, and an overlay is applied to the roughened surface.

[0002]

2. Description of the Related Art An aluminum alloy bearing used for a bearing of an internal combustion engine, for example, a connecting rod bearing, is manufactured by pressing an aluminum alloy rolling plate or a cast plate to a backing plate such as a steel plate by rolling and heat treatment. It is well known. Also, aluminum alloy bearings are used for applications such as high-load or high-power gasoline engines or diesel engines, with Sn plating via a Ni plating barrier.
Alternatively, it is well known that the Pb-based overlay is used.

Further, it is well known that Sn is generally added to aluminum alloys for bearings, and in some cases, soft metals such as Pb, In and Bi are added to add conformability, lubricity and seizure resistance. is there. In addition, as proposed by the applicant for further improving the bearing performance, Si, Cr, M
Addition of hard metal such as o, W, Fe (Japanese Patent Laid-Open No. 58-678)
41, 58-64332, 58-64334) and the like have been proposed. If necessary, a reinforcing element such as Cu or Mg may be added to the aluminum alloy for bearings.

The present applicant discloses that the surface of the aluminum bearing alloy layer is etched and roughened to enhance the adhesion of the overlay layer. International Publication WO92 / 018
Proposed in No. 72. Furthermore, a method has also been proposed in which an overlay layer is formed on a roughened uneven surface and then surface polishing is performed so that Pb or the like of the overlay and barrier plating Ni are mottled on the sliding surface (US Pat. No. 5,071,263).

In the roughening etching, etching for making the aluminum alloy into a satin finish can also be applied,
Alkaline etching that dissolves the Sn phase is preferably applied. Furthermore, the present applicant has proposed that the international publication WO92 / 018.
By the method of combining acid etching and alkali etching as shown in No. 72, the oxide of aluminum can be removed by acid and the secondary phase such as Sn can be selectively etched by alkali.

[0006]

The roughening treatment described above is performed in a state in which a bimetal in which a backing metal and an aluminum bearing alloy are joined is processed into a semi-arc shape. At this time, first, degreasing and cleaning the arc-shaped semi-finished product with foreign matter such as oil, dust, and metal pieces derived from press working, machining, etc.,
A roughening treatment is performed by immersion etching in which a large number of these arc-shaped semi-finished products are continuously passed through the tank.

The roughening treatment causes smut on the surface of the aluminum alloy layer. The smut must be removed before overlay plating, but the smut embedded in the roughened recesses can hardly be removed by physical methods such as spray washing, so the smut is decomposed by a chemical method. The method of removal is adopted. Conventionally, the smut was removed with a chromic acid-sulfuric acid type liquid or a nitric acid-hydrofluoric acid type liquid. However, with the removal of the smut, the back metal was largely eroded, and the bearing height tolerance specified in JIS D3102 fluctuated significantly.

In FIG. 4, 1 is a semi-circular bearing semi-finished product,
2 is a back metal, 3 is an aluminum alloy bearing layer, but when the entire surface of the bearing semi-finished product 1 comes into contact with the desmutting treatment liquid, the end face is eroded by the lengths a and b, and the back metal 2 is eroded by the thickness c. To be done. After that, the bearing semi-finished product 1 is attached to the housing 4
(See reference), the bearing height is reduced by a + b + c × π (π is the circular constant) from the initial bearing height.

The bearing height is related to the tightening margin when a pair of semi-arc-shaped semi-finished products 1 is assembled in an arc shape. If the tightening margin is too large, the bearing is deformed at the butting surface of the semi-finished product 1 or in the vicinity thereof. It will hit hard against the shaft and seizure will occur easily,
In more extreme cases, the housing will deform. On the contrary, if the tightening margin is too small, the bearing will not stick to the housing, so
Seizure easily occurs due to defects such as inward bending at the abutting surfaces and displacement of the bearing during sliding.

Therefore, if the bearing height fluctuates significantly due to the desmutting treatment, there is a problem in that the tightening margin varies significantly. However, it has been found that, since hydrofluoric acid or chromic acid, which has a strong decomposing action, has been conventionally used to remove the smut, the backing metal is significantly eroded and the erosion amount varies greatly.

[0011]

SUMMARY OF THE INVENTION The present invention solves the above problems and reduces bearing height defects. An aluminum bearing alloy layer is bonded to the inner surface of a semi-circular backing metal. A method of manufacturing an aluminum alloy bearing in which a semi-finished product is brought into contact with an etching solution to roughen the surface of an aluminum bearing alloy layer, and an overlay is applied to the roughened surface. The present invention also relates to a method for producing an aluminum alloy bearing, which comprises bringing the semi-finished product into contact with a desmutting treatment liquid consisting essentially of phosphoric acid and a mineral acid other than chromic acid and hydrofluoric acid. Hereinafter, the constitution of the present invention will be described in more detail.

The present invention is to improve the desmutting treatment liquid so that the smut can be efficiently removed while reducing the erosion amount of the backing metal and reducing the variation of the erosion amount between treatment batches. Therefore, mineral acids that are substantially free of hydrofluoric acid and chromic acid, such as nitric acid and hydrochloric acid, are used to decompose smut, weaken the erosive action of these acids, and evenly act on the surface of the material to be treated. It is characterized by using phosphoric acid for this purpose. Of the mineral acids, nitric acid is particularly preferred. Orthophosphoric acid is used as phosphoric acid, but a mixed acid obtained by mixing 10% by weight or less of condensed phosphoric acid may be used.

The desmutting treatment condition is not particularly limited, but is preferably 10 to 50 ° C., and in the case of the dipping treatment, the dipping time is preferably 30 to 300 seconds. The immersion treatment may be performed at room temperature. Alternatively, a spray process may be used.

In the desmutting treatment by the method of the present invention, the estimated reduction amount of the bearing height is about 10 to 15 μm. That is, the bearing material is eroded in the above range while the smut is sufficiently removed. The processing accuracy before desmutting of arc-shaped semi-finished products is determined by taking into consideration the product standard range of the value of this range and the bearing height. Since the amount of smut also changes according to the degree of bearing roughness, the height of the bearing during the desmutting process also changes, but the above-mentioned method can meet the product specifications of the bearing height. The reduction in the bearing height in the roughening treatment performed prior to the desmutting treatment is substantially not present when only the alkali treatment is performed. It is necessary to use the above liquid that selectively reacts with a secondary phase such as Sn and has little reaction with Al, Fe and the like, and a small amount of reduction in bearing height. Further, the roughening treatment can also be performed by electrolytic etching.

After the desmutting treatment, the product is washed with an appropriate amount of water and then dried. After the roughening process, perform the usual process,
For example, overlay plating is applied after applying a barrier layer such as Ni plating. Further, Zn displacement plating may be applied before Ni plating.

The concentration of phosphoric acid in the desmutting treatment solution is 20.
It is preferable that the concentration of nitric acid is -80% by weight and the concentration of nitric acid is 0.5-40% by weight. More preferably, the concentration of phosphoric acid is 50-
The concentration of 80% by weight and nitric acid is 2 to 15% by weight. Most preferably, the concentration of phosphoric acid is 60 to 70% by weight and the concentration of nitric acid is 4 to 8% by weight.

The desmutting treatment liquid may contain 20% by weight or less of a nitrogen-containing organic compound. This can prevent the generation of nitrous acid gas. As the nitrogen-containing organic compound, 20% by weight or less of a complex compound and 100 g / l or less of urea may be used. As the heterocyclic compound, pyridine, triamitriazine, dicyanodiamide, dicyanodiamidine and the like can be used, and the smut is removed together with the foam by foaming. The content of the heterocyclic compound is preferably 0.1 to 10% by weight, more preferably 0.5 to 5%.
% By weight. The preferred content of urea is 30-80 g /
1 and more preferably 40 to 60 g / l. You may use these together.

The desmutting treatment liquid may further contain 10% by weight or less of a metal salt. The metal salt stabilizes the treatment liquid by ionizing it in the desmutting treatment liquid. As the metal salt, sulfate, nitrate, etc. can be used, and as the metal, Cu, Sn, Al, Ni, etc. can be used. Preferably the concentration of metal salt is 1
~ 5% by weight.

The desmutting treatment liquid may be an aqueous solution containing the above-mentioned components, or may be composed of only the above-mentioned components without a solvent such as water.

The aluminum bearing alloy is not limited in composition, and any composition can be desmutted according to the present invention. However, it is preferable to treat an aluminum bearing alloy that can utilize an uneven surface larger than a normal matte surface for improving sliding characteristics. For example, S
An aluminum alloy in which a secondary phase consisting essentially of at least one of n and Pb is dispersed corresponds to this. In particular, the content of these elements is preferably 1 to 30% by weight. Further, it may contain at least one of Cr, Si and Cu.

Although the surface roughness of the aluminum alloy bearing layer is not limited by the roughening treatment, it is 1-10.
It is preferably μmRz. More preferably 2
It may be 7.5 μmRz.

[0022]

[Function] Conventional 30 g / l chromic acid-100 to 300 g
The smut was treated with a 1 / l sulfuric acid-based desmutting treatment solution and a method using the 70 wt% phosphoric acid-6 wt% nitric acid-based desmutting treatment liquid of the present invention. The amount of smut generated was 1 to 10 mg / cm @ 2 after the natural drying. It was typically about 4 mg / cm 2. When the effect of removing smut was visually evaluated, there was no difference between both methods, and it was found that good quality was obtained when the post-process was applied.

The change in the bearing height before and after the desmutting treatment is
The method of the present invention is shown in FIG. 1, and the conventional method is shown in FIG. These figures show that according to the method of the present invention, both the reduction amount of bearing height and its variation (σ) are significantly reduced. Further, in the conventional method, since the average value of the bearing height is reduced to the lower limit of the standard, about half of the processed bearings are defective. On the other hand, according to the method of the present invention, ± 3σ
Will fall within the standard range, resulting in a sharp reduction in defects.

Desmutting treatment is carried out by the above-mentioned method of the present invention,
After that, the surface of the back metal steel sheet after being washed with water and dried was analyzed by an X-ray diffraction method using a Cu target. As a result, a strong diffraction peak of Fe was observed in the X-ray diffraction pattern, and it was also considered that iron phosphate had a weak peak. The diffraction peak is 2θ = 38 °, 43
It was observed at ° and 55 °.

Further, when the surface of the backing steel sheet after desmutting treatment by the method of the present invention was analyzed by EPMA, P was detected as being uniformly distributed. Therefore, X-ray and EPMA
From the results, it was estimated that the iron phosphate formed on the surface of the back metal suppressed the corrosion of the steel sheet and made the corrosion uniform.

[0026]

Example A bearing material in which an aluminum bearing alloy (hereinafter referred to as "lining") having a thickness of 0.3 mm is laminated on a backing steel plate (SPCC) having a thickness of 1.5 mm has a length of 78 mm and a width of 2 mm.
It was cut into 0 mm and was bent into an arc shape in the latter half of which the cut surface was polished to obtain a semi-finished product. This semi-finished product was degreased with an aqueous solution to which a degreasing agent (Pakuna manufactured by Henkel Hakusui Co., Ltd.) was added. The aluminum bearing alloy was laminated on the back metal plate by pressure welding.

Then, the semi-finished product was immersed in a caustic soda aqueous solution having a NaOH concentration of 65 g / l for 40 seconds for roughening treatment (temperature: 55 ° C.) to obtain a surface roughness Rz of 0.8 μm. Subsequently, the semi-finished product was immersed in a smut removal solution for 60 seconds to remove the smut (temperature 30 ° C.). Subsequently, it was washed with water and dried. The desmutting treatment liquid was phosphoric acid 60
% By weight, nitric acid 4% by weight, heterocyclic compound (pyridine) 3% by weight, and the balance water. For comparison, a conventional method of immersing the semi-finished product in an aqueous solution containing 150 g / l of sulfuric acid and 40 g / l of CrO3 for 108 seconds was performed (temperature: 10 to 19 ° C).

ZnO 20 g / l, NaOH 100 g / l
Immerse the semi-finished product in a plating solution with the composition of 40 seconds (Temperature 2
7 ° C.) to form Zn displacement plating on the lining surface to a thickness of 0.1 μm. Next, the semi-finished product is lifted from the plating solution and washed with water, and the H2 SO4 concentration is 10 g /
Immerse the semi-finished product in 10 liters of sulfuric acid solution (temperature 18
(° C), the remaining Zn-substituted plating solution was neutralized.

Subsequently, 0.3 μm-thick Ni plating was formed as a barrier layer on the lining surface with a Watt bath,
Next, a Sn overlay having a thickness of 5 μm was formed by a neutral Sn plating bath.

Twenty bearing semi-finished products were processed by the method described above. FIG. 3 shows the bearing height and 3σ after polishing the cut surface and after desmutting treatment. When various nitrogen-containing organic compounds were used in the above composition instead of the pyridine,
Similar results were obtained. When urea was set to 50 g / l and the range of the present invention was followed, good results were obtained.

[0031]

As described above, according to the method of the present invention, the reduction amount of the bearing height due to the removal of the smut is 1/4 of the conventional value.
1/3, and its variation (3σ) is 1 /
Since the number of bearings is 3, it is possible to drastically reduce defective bearings.

[Brief description of drawings]

FIG. 1 is a graph showing changes in bearing height when desmutting treatment is performed by the method of the present invention.

FIG. 2 is a graph showing a change in bearing height when a desmutting process is performed by a conventional method.

FIG. 3 is an explanatory graph similar to FIGS. 1 and 2 for an example of the present invention and a conventional method.

FIG. 4 is an explanatory diagram of a dimension piece in a desmutting process of a semi-circular bearing.

FIG. 5 is an assembly diagram of a housing.

[Explanation of symbols]

 1 Arc-shaped bearing semi-finished product 2 Back metal 3 Aluminum bearing alloy (lining)

[Procedure amendment]

[Submission date] February 25, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

[Figure 5]

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area F16C 33/14 Z 6814-3J

Claims (10)

[Claims] 1. A semi-finished product in which an aluminum bearing alloy layer is joined to the inner surface of a semi-circular backing metal is brought into contact with an etching solution to roughen the aluminum bearing alloy layer, and an overlay is applied to the roughened surface. In the method for manufacturing an aluminum alloy bearing, the desmutting treatment liquid consisting essentially of phosphoric acid and a mineral acid other than chromic acid and hydrofluoric acid, and the semi-finished product after the surface roughening treatment and before overlaying. And a method for manufacturing an aluminum alloy bearing. 2. The method for producing an aluminum alloy bearing according to claim 1, wherein the desmutting treatment liquid consists essentially of phosphoric acid and nitric acid. 3. The desmutting treatment liquid has a phosphoric acid concentration of 20 to 80% by weight and a nitric acid concentration of 0.5 to 40% by weight.
The method for manufacturing an aluminum alloy bearing according to claim 2. 4. The method for producing an aluminum alloy bearing according to claim 3, wherein the desmutting treatment liquid further contains 20% by weight or less of a nitrogen-containing organic compound. 5. The method for producing an aluminum alloy bearing according to claim 3, wherein the desmutting treatment liquid contains 20 wt% or less of a heterocyclic compound and 100 g / l or less of a nitrogen-containing compound containing at least one kind of urea. 6. The method for producing an aluminum alloy bearing according to claim 3, wherein the desmutting treatment liquid further contains 10% by weight or less of a metal salt. 7. The method for manufacturing an aluminum alloy bearing according to claim 2, wherein the desmutting treatment liquid is an aqueous solution. 8. The aluminum alloy comprises Sn and Pb.
8. The method for manufacturing an aluminum alloy bearing according to claim 1, wherein a secondary phase consisting essentially of at least one of the above is dispersed. 9. The aluminum alloy comprises Cr, Si,
The method for manufacturing an aluminum alloy bearing according to any one of claims 1 to 8, which contains at least one kind of Cu. 10. The surface roughness of the aluminum alloy bearing layer is set to 1 to 10 μmRz by the surface roughening treatment.
Or the manufacturing method of the aluminum alloy bearing of 9 above.