JP2510801B2 - Pipe casting - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe stuffed cast method for forming a pipe line of an aluminum cast product by loading an aluminum pipe into a mold and casting the aluminum pipe. It is suitable for use in the production of various cast aluminum products.

[0002]

2. Description of the Related Art In recent years, in an air supply manifold for an automobile engine, an exhaust gas circulation pipe and a PCV are provided together with a distribution pipe for supplying an original fuel gas-air mixture to each cylinder.
The one with a conduit for (purge control valve) is commonly used. A cast product made of an aluminum alloy is generally used for such an air supply manifold. However, when the circulation pipe line, the PCV pipe line and the like are integrated into the manifold body, the pipes are thin and long, and therefore, cast. Since it is difficult or impossible to set with the mold configuration of No. 1, the thick part previously provided in the casting is perforated by mechanical processing after casting, or it is cast by loading an aluminum pipe in the mold (pipe casting method) Thereby, the means for forming the conduit is adopted.

[0003] In particular, the latter case of the cast-in-gurgling method has the advantage that the former can be omitted from the mechanical work and is suitable for mass production, and that a curved pipe line which is difficult or impossible to form by the mechanical work can be easily formed. Further, melting damage of the pipe during casting can be prevented by forming a heat resistant coating on the surface of the pipe as disclosed in JP-B-57-31499.

[0004]

However, the aluminum pipe arranged in the mold in the cast-in-turn method is
Generally, the temperature of the molten aluminum is about 670 to 750 ° C. However, this heat inevitably causes a decrease in rigidity and distortion due to heat even when the heat resistant coating is included, and the main flow of the molten metal in the mold during casting. When the direction crosses the longitudinal direction of the pipe, the pipe whose rigidity is lowered is likely to be bent by the pouring pressure, and the bending is more remarkable as the crossing angle becomes closer to 90 degrees, However, there was a problem that the wall thickness of the cast product becomes thin, and in an extreme case, the wall thickness breaks, leading to product defects.

In order to prevent such bending of the pipe during casting, a mold having a receiving seat that abuts the pipe on the bending direction side is used, or the inside of the pipe during casting is externally exposed. It is possible to send more air or the like to cool. However, in the former case, it is necessary to fill the hole after casting with the receiving seat by welding or resin encapsulation, and this post-processing requires a great deal of trouble, and in the latter case, there is a problem in that it affects the quality of the casting. It is very complicated and difficult to control the temperature and the amount of cooling medium introduced, and the molten metal that is pouring is rapidly cooled around the pipe and solidifies quickly, making it difficult for the molten metal to spread to the inner depth side from the pipe position. In particular, when the thickness of the cast product at the position of the pipe is thin (that is, the molten metal flow path is narrow), there is a drawback that clogging occurs at the solidified portion and defective casting frequently occurs.

[0006] In view of the above situation, an object of the present invention is to bend the aluminum pipe arranged in the mold regardless of the direction of the arrangement when forming the pipe line by the cast pipe casting in the casting of the aluminum casting. Providing a casting method that can be reliably prevented, and that does not require complicated control during casting or post-processing after casting, can efficiently obtain high-quality cast products with high yield, and is excellent in mass productivity and practicality. Especially.

[0007]

[Means for Solving the Problems] As means for achieving the above-mentioned object, in a pipe cast gurney casting method according to claim 1 of the present invention, an aluminum pipe is placed in a mold and molten aluminum is poured, In the case of the round-the-wall casting method in which the pipe is cast to form a pipe line of an aluminum cast product, in the aluminum pipe in which the longitudinal direction of the pipe crosses the main flow direction of the molten metal at the time of pouring, A rod or a metal stranded wire is fitted and inserted over the entire length of the pipe so as to be in contact with the inner surface thereof, and the metal rod or the stranded metal wire is extracted after pouring and solidifying in this fitted state. It was done.

[0008] According to a second aspect of the present invention, there is provided a cast-in-a-roll casting method according to the first aspect of the present invention, in which a heat-resistant coating is provided on the surface of the aluminum pipe.

[0009]

[Operation] When placing an aluminum pipe in the mold and pouring it,
As it is, the pipe is hollow and has a small heat capacity, so that the temperature rapidly rises and the rigidity is lowered, but in the configuration of the present invention, the metal rod or the stranded metal wire is provided inside the pipe over the entire length of the pipe. Since it is inserted so as to be in contact with the inner surface of the pipe, the heat capacity as a whole including the inside of the pipe is remarkably increased, and in addition, the heat conductivity of the metal rod material or the metal stranded wire material is good. The heat transferred is efficiently and quickly absorbed by the internal metal rod or stranded metal wire evenly over the entire length of the pipe, and the temperature of the pipe itself does not rise so much and sufficient rigidity is maintained. In particular, when the main flow direction of the molten metal at the time of casting intersects with the longitudinal direction of the aluminum pipe, the material or the metal stranded wire also fulfills a mechanical reinforcing function as the core material of the pipe during pouring. Even when the crossing angle is right, the bending of the pipe due to the pouring pressure is surely prevented, and the distortion due to the partial temperature difference of the pipe itself is also prevented. For example, even a thin aluminum pipe with a thickness of about 1 mm It is possible to obtain a cast-molded pipe that is not deformed by heat and is homogeneous throughout. The term aluminum used in the present invention includes aluminum and its alloys.

In addition, the metal rod and the metal stranded wire which are inserted into the above-mentioned aluminum pipe are replaced by a heat-resistant material such as granular, chip-like or powder-like material in comparison with the case where the pipe is loaded with the heat-resistant material. In addition, a large contact area with the inner surface of the pipe can be secured, and the operability of inserting into the pipe and withdrawing from the pipe after casting is excellent, and morphologically easy to handle. Although there is no particular difference in terms of functionality between the metal rod and the stranded metal wire, for example, if the pipe to be formed is a straight pipe or a simple arc pipe, a metal rod or a bent pipe should be extracted after casting. In order to facilitate the above, a flexible metal stranded wire material may be used.

In the casting method of the present invention, the metal rod or the metal stranded wire is inserted into the aluminum pipe so as to come into contact with the inner surface thereof over the entire length of the pipe as described above, but the temperature rise of the pipe is further reduced. If necessary, one end or both ends of the metal rod-shaped material or the metal stranded wire material may be sandwiched between the upper and lower molds so that heat is discharged to the mold by heat conduction, and further the one or both ends are led out of the mold. It is also possible to positively cool it with air, water, oil or the like.

The aluminum pipe is preferably provided with a heat resistant coating on the surface thereof in order to enhance the resistance to molten metal. This coating is obtained by coating and drying a dispersion liquid of a metal oxide powder or an easily oxidizable metal powder, and the above-mentioned JP-B-57-31.
Any chemical conversion coating as disclosed in Japanese Patent Publication No. 499 may be used as long as it has heat resistance to withstand the temperature of the molten aluminum. Further, the pipe may be provided with a small hole for degassing in order to prevent generation of a porosity due to partially decomposed gas of the coating film.

During casting, the upper and lower molds are preheated, and the aluminum pipe in which the metal rod or the twisted metal wire is inserted in the lower mold is set at a required position, and the upper mold is set. After covering the lower mold and pouring molten aluminum into the mold, the solidified casting is removed from the mold, and the metal rod material or the metal stranded wire material may be extracted from the pipe cast therein. The extracted metal rod material or metal stranded wire material can be used repeatedly, and can be continuously used several times without cooling under normal casting conditions. The temperature of the preheating is usually 330 to 430 ° C. for the upper mold, about 280 to 330 ° C. for the lower mold, and the temperature of the molten aluminum is 67.
It is about 0 to 750 ° C.

[0014]

1 and 2 show an intake manifold M for a four-cylinder automobile engine made of an aluminum cast product manufactured by applying the casting method of the present invention. This manifold M
Is an intake header 1 that introduces a gasoline-air mixture.
The four branch pipes 2 ... Corresponding to each cylinder of the engine extend further, and the end portions of the branch pipes 2 ... Are integrated to form the mounting flange portion 3 for the engine body, and the branch pipes 2 ... The horizontal cross section 4 connected at the front side of the middle section (Fig. 1)
The horizontal rail 4 is provided with a PCV pipe line 5 in the form of a straight pipe in a direction substantially perpendicular to the respective branch pipes 2 and an aluminum pipe 6.
It is configured by casting.

In the manufacture of the intake manifold M, it is preferable to form a heat-resistant coating on the surface of the aluminum pipe 6 and, for example, as shown in FIG. 4, steel having an outer diameter slightly smaller than the inner diameter of the pipe 6 is used. The rod 7 is fitted and set in the lower mold of the preheated mold 8 together with the core 9 in a state where the steel rod 7 is in contact with the pipe inner surface over the entire length of the pipe 6, and the upper mold preheated to the lower mold. The aluminum rod was poured into the mold, and after solidification, it was taken out from the mold.
By pulling out the pipe 6 cast as shown in FIG.
The PCV conduit 5 according to the above is constructed, and then machining for forming attachment tap holes and the like may be performed. In this case, since the respective branch pipes 2 are arranged substantially at right angles to the PCV pipe line 5, the main flow direction of the molten metal at the time of pouring is substantially orthogonal to the longitudinal direction of the pipe 6, and the pipe 6 The largest fluid pressure will act on. Next, an example of actual casting will be specifically described.

Example 1 An aluminum pipe (melting point 660 ° C.) having a thickness of 1 mm and an outer diameter of 10 mm was degreased with an aqueous solution of sodium hydroxide, neutralized with an aqueous solution of nitric acid, washed with water, and then an aqueous solution of zinc fluoride having a concentration of 3% by weight. Immerse in it at room temperature for 10 minutes and wash it with water to 100
A heat resistant coating was formed by drying at ˜120 ° C. for 10 minutes. Next, a steel rod having a diameter of a little less than 8 mm was inserted into this pipe, and this was set in the lower mold of the mold preheated to 280 to 350 ° C. along with the core while being in contact with the pipe inner surface over the entire length of the pipe, The lower mold was covered with an upper mold preheated to 330 to 430 ° C., molten aluminum at 670 to 750 ° C. was poured, and after 2 minutes, a solidified casting was taken out from the mold. Then, the steel rod in the cast pipe was extracted, and an intake manifold cast product having a structure shown in FIGS. 1 to 3 and having a thin portion from the header 1 to each branch pipe 2 having a thickness of 3 to 5 mm was manufactured.

Example 2 Example 1 was repeated except that a composite twisted steel wire having a diameter of slightly less than 8 mm was inserted into an aluminum pipe instead of the steel rod.
An intake manifold cast product was manufactured in the same manner as in.

Example 3 An intake manifold cast product was produced in the same manner as in Example 1 except that an aluminum pipe having no heat resistant coating was used.

COMPARATIVE EXAMPLE 1 An intake manifold cast product was manufactured in the same manner as in Example except that an aluminum pipe was set in a mold without inserting a steel rod.

Comparative Example 2 An intake manifold cast product was manufactured in the same manner as Comparative Example 1 except that an aluminum pipe having no heat resistant coating was used.

Comparative Example 3 An intake manifold cast product was produced in the same manner as in Example 1 except that an aluminum pipe was filled with steel balls having a diameter of 8 mm instead of the steel rod.

For each of the 20 intake manifolds cast by the methods of the above-mentioned Examples and Comparative Examples, it was examined whether or not the PCV pipeline 5 was curved or broken, and the aluminum pipe was melted or damaged. The results shown in the table below were obtained.
In the table, the mild curvature indicates that the degree of bending is within a range allowable as a product, and the severe curvature and the wall thickness breakage indicate defective products.

[0024]

[Table 1]

[0025]

According to the cast-in-gurney casting method of the present invention, in the production of an aluminum cast product, a pipe path is formed by the cast-in-girth of an aluminum pipe, particularly the longitudinal direction of the pipe is relative to the main flow direction of the molten metal during pouring. When forming a pipe line in a state where the pipes intersect with each other, by inserting a metal rod or a metal stranded wire into the pipe, by an extremely simple operation of taking out the metal rod or the stranded metal wire after casting, It is possible to reliably prevent the bending of the aluminum pipe placed in the mold, for example, a thickness of 1 m
Even thin aluminum pipes with a thickness of about m can be made into a cast-mellow pipe that is homogeneous throughout without any thermal deformation, and has special post-processing after casting, as well as the temperature and flow rate during casting such as when using a cooling fluid. It does not require complicated control, and does not cause quality deterioration due to supercooling around the pipe or defective casting due to obstruction of molten metal flow.Moreover, the metal rod and metal stranded wire rod can be inserted into and removed from an aluminum pipe. It is excellent in operability and easy to handle, so that a high-quality cast product having the above-mentioned pipeline can be efficiently manufactured at a high yield at a low cost.

Further, according to the second aspect of the present invention, there is an advantage that the melting loss of the cast aluminum pipe can be surely prevented.

[Brief description of drawings]

FIG. 1 is a front view of a four-cylinder intake manifold for an automobile engine, which is an example of an aluminum cast product manufactured by applying the present invention.

FIG. 2 is a side view of the intake manifold.

FIG. 3 is a cross-sectional view of a portion corresponding to the line AA of FIG. 1 in the intake manifold after casting.

FIG. 4 is a cross-sectional view of a PCV conduit portion at the time of casting of the intake manifold.

[Explanation of symbols]

 5 PCV Pipeline (Pipelined Pipeline) 6 Aluminum Pipe 7 Steel Rod 8 Mold M Intake Manifold (Aluminum Cast)

Claims (2)

(57) [Claims] The method according to claim 1] to pouring the molten aluminum by placing an aluminum pipe into a mold, in the pipe insert casting casting constituting a conduit aluminum castings by casting the pipe, pouring time of the molten metal The longitudinal direction of the pipe with respect to the main flow direction of
In the aluminum pipe in a crossing relationship, a metal rod or a metal stranded wire is fitted and inserted over the entire length of the pipe so as to be in contact with its inner surface, and the metal rod or the metal rod is poured after solidification in this fitted state or solidified. A pipe stuffed toy casting method characterized by extracting a stranded metal wire. 2. The pipe cast gurney casting method according to claim 1, wherein a heat resistant coating is provided on the surface of the aluminum pipe.