JPH0120948B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for easily manufacturing cylinders with superior properties.

Efforts are being made to reduce the weight and cost of engines, compressors for car coolers, etc. in order to save energy. In particular, cylinders for engines and car cooler compressors need to be lightweight, have excellent wear resistance and lubrication properties, and have long-term durability. Al and Al alloys are used to reduce weight, but since Al and Al alloys have poor wear resistance and lubrication properties, the following methods are used to impart these properties: (1) Cast iron cylinders Liner casting method, (2) Coating method by thermal spraying on the inner surface of the cylinder, (3) Coating method by wire blast spraying on the inner surface of the cylinder, (4) Method for plating the inner surface of the cylinder, (5) Made of high-Si aluminum alloy. Cylinder honing methods and (6) cylinder press-fitting methods for sintered and cast iron castings have been devised and applied, but each of these methods has the following drawbacks and has not been put into practical use. There are things that aren't there.

In other words, (1) and (6) result in an increase in weight, (2) is the difficulty of thermal spraying on the inner surface of a small diameter cylinder, and (3) to (5) are costs, product yield, and uniformity of manufacturing technology quality. There are quite a few problems.

On the other hand, in addition to the above method, a thermal spray coating is formed on the surface of the core material using a core material, the core material with the sprayed coating formed is placed in a mold as it is, and the desired material is cast. A thermal spray coating transfer method for transferring a thermal spray coating has been proposed. In this method, the core material with the sprayed coating is placed directly into the mold and cast under high temperature and pressure. Therefore, when Al material is used for the core material, the core material is heated and softened during casting, causing deformation. In addition, when the core material is finally removed, the core material may be deformed, or scratches may occur due to sliding on the die-casting mandrel, and it takes a considerable amount of time to remove the core material. In addition, products that require cutting when the core material is finally taken out are expensive because the core material cannot be reused, and products that reuse the core material require undercoating, which increases costs. .

The present invention eliminates the drawbacks of the thermal spray coating transfer method and provides a method for manufacturing cylinders that is lightweight, has excellent abrasion resistance, and lubrication properties, and is intended to achieve mass production and cost reduction of the cylinder manufacturing method. .

The present invention uses a material with a large coefficient of thermal expansion (such as Al material) for the core material, expands the core material by heating before thermal spraying, and forms a thermal sprayed coating with excellent sliding properties on top of the core material. When the core material is then cooled, the core material contracts due to the difference in thermal expansion coefficient between the thermal spray coating and the core material, causing the core material and the thermal spray coating to peel off. By directly covering the mandrel or casting core for cylinder forming of a die-casting machine with this peeled film and casting it around the outer periphery, the thermal sprayed material with excellent sliding properties can be applied to surfaces that require sliding properties such as cylinders. Unlike the conventional method where the thermal sprayed coating is placed into the mold together with the core material, only the coating is used, so it is easier to take out the core material,
All drawbacks related to reuse have been eliminated.

The present invention will be explained in more detail using the accompanying drawings.

FIG. 1 shows core materials used in the present invention, with 1 showing a pipe-shaped core material and 2 a solid core material.

Either (1) or (2) may be used, but pipe material is more effective in terms of mass productivity of thermal spraying and heating processes, manufacturing cost, etc. In addition, as mentioned above, the material has a coefficient of thermal expansion as large as possible and will not soften, generate heat, deform, or burn during thermal spraying, and will not dissolve or deform when exposed to organic solvents or other degreasing agents. In particular, it is preferable to use a material that does not undergo dimensional changes due to factors other than temperature rise due to structural changes, growth of the structure, recrystallization, etc. due to thermal spraying or heating. Taking these factors and cost into consideration, non-heat-treated Al
The material was the most suitable.

The core shape has a slight taper on the outer periphery, considering the ease of separating the coating after thermal spraying and the ease of fitting into the core during casting (tapering is not necessary if only separation is required). In addition, care must be taken to avoid chamfering the end faces and to give the surface a good finish of about 100 ml. 〓〓
〓The finish indicates precision finishing, and the range of roughness is
It indicates a surface roughness of 6.3μ or less.

The reason for using a tapered core shape is as follows.
In addition to the above, when performing die casting, in order to prevent the thermal spray coating from being damaged by the casting pressure of the die casting, it is also necessary to adhere closely to the tapered mandrel of the die casting, and this shape is not suitable for gravity casting or low pressure casting. This necessity is not recognized, and a parallel shape may be sufficient. In addition, the surface roughness was finished at the level of 〓〓〓, but this is because the roughness of the core surface is transferred to the joint of the thermal spray coating with the core surface, so if the surface roughness is made rough, the surface roughness of the core will be The roughness of the contact surface of the core during thermal spraying requires a gap that is at least twice as large as the roughness of the meshing surface, so it is best to have as fine a roughness as possible. In the case of a parallel core using a drawn pipe, etc., the drawn surface can be used as is.

These core materials are sufficiently degreased using an organic solvent, etc., and a predetermined thermal sprayed material with lubricating properties and wear resistance is applied as a cylinder material to the outer periphery of the core materials 1a and 2a, as shown in Figure 2. Thermal spraying is performed to a thickness to form a thermal sprayed coating 3.

Regarding the materials to be thermally sprayed, the expected properties differ depending on the cylinder used, and as a result, the required properties of the coating also differ. superalloys such as Al, Al alloys Cu, Cu alloys Zn, Sn, non-ferrous metals and their alloys), ceramics (Al ₂ O ₃ , SiO ₂ , TiO, WC, CrO ₂ ,
Select the material that meets the required characteristics from among oxides such as ZrO and TiC, compounds such as carbides, boride nitrides, and silicides, and mixtures thereof) and cermets (mixtures of ceramics and metals, etc.). .

The thermal spraying method may be any thermal spraying method, such as flame thermal spraying using a wire, electric arc thermal spraying using a wire, flame thermal spraying using a powder, or plasma thermal spraying, but the method should be selected as appropriate depending on the thermal spraying material.

The thickness of the thermal spray coating is very easy to select from a design perspective as the sprayed coating will be transferred as is, but considering casting accuracy, processing accuracy, etc., it is thought to be about 0.5 to 5 mm, and it is expected that about 0.5 to 1.5 mm will remain after processing. To,
The thickness of the sprayed coating is not particularly limited, and may be determined by considering each processing accuracy.

In addition, before thermal spraying, the core materials 1a and 2a are sufficiently heated by preheating, and at the same time, the formation of irregularities that increase the anchoring effect, such as blasting or thread cutting, is not performed.
It is necessary to thermally expand the diameter of the outer periphery. After that, when it is cooled, a gap is created between the core material and the thermal sprayed coating due to the difference in thermal expansion coefficient between the core material and the thermal sprayed coating, so the thermal sprayed coating and the core are easily separated, resulting in a coating as shown in Figure 3. 3 can be taken out. Thereafter, the sprayed coating 4a is applied to a sand mold for forming a cylinder such as a mold 7 or a mold 7a, or a sand mold core or a mandrel 6 of a mold, as shown in FIG. A desired material such as an Al alloy is cast into the space 5 of the mold, and the thermal spray coating is transferred. Thereafter, the product is cooled and taken out from the mold, and as shown in FIG. 5, the transferred thermal sprayed layer that becomes the cylinder is processed 8 (the inner diameter side of the tapered thermal sprayed coating is removed) to obtain a desired cylinder 5a. In this case, the situation of the transfer area is as shown in Figures 6 and 7. If the surface of the thermally sprayed layer remains after being thermally sprayed, the surface of the thermally sprayed layer will be uneven due to the thermally sprayed particles, and this will act as an anchoring effect on the cast base metal. The sprayed coating clings firmly to the metal molded into the main body.

According to the present invention, only the thermal sprayed coating that is to become the cylinder surface is manufactured by an automated and simple external thermal spraying method using a core material made of Al material with a large coefficient of thermal expansion (the core is not damaged in any way). (Can be used continuously), this is firmly transferred to the inner surface of the casting or cylinder using the conventional die casting method, metal mold casting method, or sand mold casting method, resulting in high precision and wear resistance. Cylinders can now be manufactured.

The cylinder manufacturing method of the present invention is suitable for use in cylinders for air, hydraulic, and refrigeration compressors including car cooler compressors, engine cylinders, cylinder parts used by casting that require good sliding properties, and casting during injection molding of plastics. It is applied to the manufacture of parts such as cylinders that require sliding characteristics due to wrapping.

Example 1 A 5052 series Al pipe with an outer diameter of 60 mm and a wall thickness of 8 ^t mm was made to have a length of 100 ^l mm with the inner diameter unchanged, and the smaller outer diameter side was 58.0 mm and the larger outer diameter side was 59.0 mm. The core material was processed into a tapered shape. At this time, the core material is non-heat treated aluminum (1000 series, 3000 series
5000 series) and austenitic stainless steel can be used. In this example, availability,
Considering the strength aspect, we used 5052 series Al pipe. At this time, the inner diameter side was left as is, the outside diameter was machined to a finish of 〓〓〓 (about Rmax 8μ), and the inner diameter end face was chamfered to about ^2c , but the outer diameter side was not chamfered. did. Thereafter, the core material was vapor degreased using trichloride to make the surface clean and free of any oil or fat. Handle all degreased core material with clean gloves to avoid contaminating the surface. Approximately 15 of these cores were passed through a 44 mm rod-shaped jig. At this time, heat-resistant rubber with an inner diameter of 44〓mm, an outer diameter of 60〓mm, and a thickness of 1 ^tmm is inserted between the cores, both ends are fixed, and 15 pieces are combined into one.
The cores were heated as one set using a torch or a heating furnace to a temperature of about 240° to 260°C. Immediately after that, wire gas spraying is applied to the entire outer diameter.
Low alloy steel (Ni4%, Mo1~3
%, Cr1.5%, Mn2%) sprayed. The large diameter side of the core material during this heating becomes 59.35〓mm, and thermal spraying is applied onto this diameter. After that, when it is cooled, the diameter of the large diameter side returns to the 59.0〓mm at the time of processing, and at the same time the inner diameter of the sprayed coating also shrinks slightly to about 59.17〓mm, with a difference of about 0.17mm.
This becomes the gap between the core and the sprayed coating.
On the other hand, the surface of the sprayed base material has a roughness of about 8μ, so if there is a gap of 8μ×2=16μ or more, it will come through. Also, the core has a taper of about 5/100mm, so a slight movement will create a larger gap. However, in general thermal spraying, the surface is activated by threading or blasting, and at the same time, the anchoring effect is used to increase the adhesion to the base material as much as possible, but in the present invention, The sprayed layer is formed without these treatments, but since the adhesion strength to the base material is extremely weak, the above dimensional difference causes the coating to not follow the base material and a space is created, causing the core and the sprayed layer to form. The coating is separated and only the sprayed coating can be taken out.

In this way, apply the created thermal spray coating to the mandrel of the die-casting machine (5/5cm so that the thermal spray coating is in close contact with the die-casting machine).
Place it over a mandrel with a 100mm taper.
Then, aluminum alloy (ADC12) was die-cast there. Thereafter, the cylinder was punched out from a die-casting machine mold and processed to the specified dimensions at the center of the cylinder. In addition, the result of observing the situation of the thermal spray transfer part of the cylinder after processing shows that the transferred film is in the circumferential direction,
There was no unevenness in thickness in the longitudinal direction, and the film was properly transferred to the Al alloy side, with good adhesion. In addition, after assembling the completed cylinder and operating it continuously for 240 hours at 1800 rpm as a 1-cylinder 4-cycle 8ps agricultural engine, we found that there were no abnormalities on the inside of the cylinder or on the sliding surface of the Al alloy piston. Good results were obtained, with no difference in oil consumption compared to conventional engines.

Example 2 A 5052 Al pipe with an outer diameter of 50 mm and a wall thickness of 6 ^t mm was
47 ^l mm, the outer diameter is tapered to 49.3〓mm on the large diameter side and 49.0〓mm on the small diameter side. Surface roughening, end face processing, etc. were performed in the same manner as in Example 1. Further, 0.8% C steel was thermally sprayed using the same pretreatment, heating, and thermal spraying methods as in Example 1, except that the thermal spraying method was a wire-type electric arc gun method. After that, the sprayed coating was separated from the core, the sprayed coating was taken out, and the same method as in Example 1 was used to make a two-cylinder compressor for a car cooler.The sprayed coating was cast into the cylinder part by die-casting, and the sprayed coating was finished to the specified dimensions at 8000 rpm. As a result of 50 hours of continuous durability operation, there were no abnormalities on the inner surface of the cylinder or the sliding surface of the Al alloy piston, and there was no difference in compression performance compared to the conventional model.

[Brief explanation of drawings]

Fig. 1 is a side view and cross-sectional view of an example of the core material used in the present invention, Fig. 2 is a view of the core material of Fig. FIG. 2 is a diagram showing only the thermal spray coating taken out from FIG. 2; Figures 4 and 5 show how to actually apply the sprayed coatings obtained in Figures 1 to 3 to cylinder molds to manufacture cylinders, and Figures 6 and 7 show how the sprayed coatings obtained in Figures 1 to 3 are applied to cylinder molds. This is a representative microscopic tissue diagram.

Claims (1)

[Claims] 1. In a method of manufacturing a cylinder with a coating with excellent cylinder properties formed on its surface by transferring a thermal spray coating, a core material with a coefficient of thermal expansion larger than that of the thermal spray coating to be transferred is used, and the core material is heated before thermal spraying. A sprayed coating is formed on the thermally expanded material, and after cooling, only the sprayed coating is taken out due to the dimensional difference caused by the difference in thermal expansion coefficient between the sprayed coating and the core material, and this sprayed coating is applied to the cylinder after casting. A cylinder manufacturing method that consists of covering the mold part of the cylinder so that it forms the surface, and then transferring the casting and thermal spray coating to the outer periphery.