JP2003010945A - Device of casting wheel for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling part body for casting a robust wheel product for automobiles. SOLUTION: Since this casting device is provided with an entire cooling part 16a for cooling the whole insert 8a and a point cooling part 14a for forcibly cooling a hub part 54, the robust wheel product for automobiles having no defect or the like can be cast. Further, by interposing a buffer material 13 for buffering thermal expansion/shrinkage between the insert 8a and either one of the entire cooling part 16a or the point cooling part 14a, or both parts of the cooling part body 9a, it can be prevented to generate a cavity in a contact part of the insert 8a and the cooling part body 9a by thermal expansion or shrinkage deformation. Furthermore, since the casting device does not need to previously arrange an escape space 18 anticipating the thermal expansion or shrinkage deformation, a pertinent cooling effect can be obtained, thus efficiently producing the robust wheel product.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting device used for molding automobile wheels.

[0002]

2. Description of the Related Art In the process of casting a wheel for an automobile by pouring the molten metal into a cavity of a mold, the center of the wheel serving as a hub is used as a sprue, and the molten metal is transferred from the spoke forming channel of the cavity to the rim forming channel. Is completely injected into the rim forming runner, and then the cooling process is started, and the rim forming runner gradually moves from the edge of the rim forming runner to the spout forming runner to the sprue. An automobile wheel is manufactured by solidifying and forming.

In such a cooling process, if the molten metal injected into the cavity is improperly solidified when it is cooled, bubble cavities, shrinkage cavities, cracks, surface defects, shape defects and the like are likely to occur. Therefore, by properly cooling the molten metal, it is possible to manufacture a sound product free from the defects. In addition, since a predetermined shape can be formed by replenishing the molten metal at any time with respect to heat shrinkage that occurs when the molten metal solidifies, a cooling means is used that appropriately solidifies and replenishes the molten metal in the cooling step. That is an important point for efficiently obtaining healthy products.

[0004]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention
Since it has a complicated shape, the wall thickness and the like of each portion are different, so that the progress of solidification is different for each portion during cooling, which tends to cause defects such as the above defects. Therefore, during the cooling process, the vicinity of the sprue, which is a relatively high temperature region, is positively cooled, and the time from the start of solidification at the end of the rim to the end of solidification in the entire region is shortened, so that the entire wheel is It is common to produce a sound product by creating a situation in which the solidification of the slag gradually progresses from the end of the rim toward the sprue.

In the above-mentioned automobile wheel, since the hub portion to which the thin spokes are joined is a portion requiring high mechanical strength due to the property of the product, it generally has a thick shape. Target. Therefore, it is necessary to enhance the cooling effect on the hub portion so that the solidification of the hub portion can be appropriately performed with respect to the solidification of the surrounding parts. As a cooling method for this purpose, conventionally, a passage is provided for injecting a cooling fluid into the insert, and the passage has a structure in which the flow rate of the cooling fluid is increased in a portion where the cooling action is most necessary, or In general, a cooling unit is separately provided and the cooling unit is installed at a predetermined position of the insert. However,
In the former case, since the passage is provided by making a hole in the insert, the durability of the insert is reduced, and the cost for processing the passage increases. Further, in the latter case, in order to avoid adverse effects due to thermal expansion contraction deformation between the insert and the cooling unit,
It was necessary to flatten the contact surface between the insert and the cooling unit, and it was difficult to locally enhance the cooling action. The present invention aims to solve such problems.

[0006]

SUMMARY OF THE INVENTION The present invention is a casting device for an automobile wheel, in which a thin portion is formed on the sprue forming runway at the sprue side, and the surface facing the spoke portion forming runway is provided on the thin side. An insert forming a cavity of an automobile wheel mold having a partial flat surface, and a surface of the thick wall portion excluding the thin wall portion, which faces the spoke part forming runway, being a thick wall side main surface, and a thick wall side. A cooling part body comprising an entire cooling part in contact with the main plane and a point cooling part in contact with the thin side partial plane, and between the point cooling part and the thin side partial plane or / and the entire cooling part and the thickness. It is characterized in that a thermal expansion / shrinkage buffer material is interposed between the meat side main plane.

As described above, as a nest of a wheel mold for an automobile, a cooling portion is brought into contact with a thin portion formed on a sprue side of a spoke forming passage and a thick portion other than the thin portion, respectively. While the overall cooling unit can increase the cooling speed of the automobile wheel as a whole, the point cooling unit can locally and forcibly cool the hub portion to which the spokes are joined in accordance with the cooling speed. A cooling action can be generated, and the solidification of the molten metal can proceed from the outermost end of the rim portion toward the sprue as sequentially as possible, so that a sound product can be efficiently manufactured.

The above cooling unit has a stepped structure consisting of a point cooling unit and an entire cooling unit, and the main purpose of the point cooling unit is to locally cool the portion where the spokes are joined to the hub portion. Therefore, it may be installed only at a position corresponding to the hub part where the spoke parts of the automobile wheel are joined, or may be installed over the entire circumference of the hub circumference. On the other hand, the overall cooling unit may be configured over the entire circumference of the wheel, or a plurality of cooling unit bodies may be configured corresponding to the installation position of the point cooling unit.

As a cooling method for such a cooling unit,
General water cooling, air cooling, or the like can be used, and it is possible to provide a flow path through which the cooling fluid flows in the cooling section body and perform cooling by injecting the cooling fluid into the flow path. . Such a cooling fluid flow path can be provided in each of the point cooling unit and the entire cooling unit, and thus the cooling action of the point cooling unit can be further enhanced.

As a nest cooled by the cooling unit according to the present invention, a thin side partial plane surface and a thick side main plane surface are formed in the nest in order to obtain a proper cooling action from the point cooling section and the whole cooling section. However, the contact surfaces of the insert and the cooling member are in plane contact so that the contact surfaces are cooled uniformly.

The thickness of the thin portion of the flat surface on the side of the thin portion formed in such a nest can be set to an appropriate shape depending on the shape and material of the automobile wheel to be cooled.

On the other hand, in the above-described cooling process of the casting apparatus, the temperature of the insert is about 400 ° C. to 500 ° C., while the cooling body is about 100 ° C. A change in thermal expansion and contraction occurs in the insert and the cooling section body, and a compressive load acts on the contact surface between the point cooling section and the thin-side partial plane and the contact surface between the entire cooling section and the thick-side main plane. Or the contact surface may be separated.
Therefore, a configuration (not a known example) in which an escape space is provided in anticipation of thermal expansion / contraction deformation is also considered, but in an escape space provided in advance between the entire cooling part and the thick side main plane. Since the thermal conductivity of air is low, the cooling effect becomes insufficient, and the required cooling effect cannot be obtained. Therefore, as a result of further intensive study, the inventor can absorb the above thermal expansion / contraction shrinkage deformation between the point cooling part and the thin side partial plane or / and between the entire cooling part and the thick side main plane. It came to interpose a thermal expansion / shrinkage buffer material. By using the thermal expansion / shrinkage cushioning material in this way, it is possible to prevent a load from being applied between the cooling section body and the insert due to thermal expansion / contraction deformation, or to create a space, and to provide a sufficient cooling effect. It was to be demonstrated.

Since the shape of the insert and the cooling part and the temperature difference between the insert and the cooling part affect the thermal expansion and contraction deformation, the point contact cooling is used as the contact surface for interposing the thermal expansion and contraction member. Expansion and contraction deformation that occurs on the contact surface between the cooling section and the thin side partial flat surface is compared with the thermal expansion and contraction deformation that occurs on the contact surface between the entire cooling section and the thick side main surface, and a larger amount of deformation occurs It is effective to interpose a thermal expansion / shrinkage buffer material on the other contact surface. Further, a thermal expansion / shrinkage buffer material may be provided on both contact surfaces depending on the deformation amount and the deformation action.

Since the above-mentioned thermal expansion cushioning material is required to be able to sufficiently transmit the cooling action from the cooling part,
It is proposed to use materials with high thermal conductivity. Further, by making the thermal expansion / contraction cushioning material an elastic body having a high elasticity, both are constantly in contact through the thermal expansion / contraction cushioning material even if the insert or the cooling member is deformed by thermal expansion / contraction. For,
Heat conduction can be sufficiently performed. In addition, a material having sufficient heat resistance in the temperature range of the insert during casting is preferable. Further, a material having a higher coefficient of thermal expansion than the insert and the cooling unit may be used.

As such a thermal expansion / contraction material, a carbon material such as copper or graphite can be used. Above all, a graphite sheet member made of graphite, which has high thermal conductivity, high elasticity, and heat resistance, and
It is proposed to use a carbon fiber non-woven fabric composed of short carbon fibers. In particular, the graphite sheet member
Since the restoration rate when compressed is also high, the durability against repeated use is also high.

As the above-mentioned thermal expansion / shrinkage buffer material, the thickness of the material is generally inversely proportional to the thermal conductivity, so that it is preferable that it is thin from the viewpoint of thermal conductivity. On the other hand, it is necessary to have a thickness that can support the amount of thermal expansion / contraction deformation of the insert and the cooling unit, so an appropriate thickness is considered in consideration of the shapes of the insert and the cooling unit and the maximum temperature difference between the insert and the cooling unit. Need to decide.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a casting mold 1 for molding an automobile wheel. The cavity 5 is formed by combining the upper mold 2, the lower mold 3, and the horizontal molds 4 and 4. The cavity 5 includes a hub portion 54, a spoke portion 52, and a rim portion 53.
The molten metal is injected from the stalk 6 through the molten metal injection passage 7 through the molten metal inlet 51, passes through the molten metal passage of the hub portion 54, the spoke portion 52, and the rim portion 53, and is filled with the molten metal. A cooling unit 9 is installed on the insert 8 that is assembled to the lower mold base to form the lower mold 3, and the molten metal is solidified by the cooling action of the cooling unit 9 or the like to manufacture an automobile wheel.

FIG. 2 is an enlarged view of the insert 8a of the mold 1 and the cooling body 9a. The thin portion 10 is formed on the insert 8a as a place where the hub portion 54 between the sprue 51 and the spoke portion 52 can be locally cooled, and the thick portion 12 other than the thin portion 12 is formed.
Are formed. Partial plane 11 on the thin side of the thin portion 10
The point cooling unit 14a of the cooling unit body 9a is pressed against the thermal expansion and contraction cushioning material 13 via the thermal expansion and contraction cushioning member 13. Further, the entire cooling portion 16a of the cooling portion body 9a is in contact with the thick side main plane 15a of the thick portion 12. Here, the thermal expansion / shrinkage buffer material 13
As the graphite sheet member,

The thermal expansion / shrinkage cushioning material 13 includes the thick side main plane 15a of the insert 8a and the entire cooling portion 16a of the cooling portion body 9a.
Can be intervened between
Between the thin-side partial flat surface 11a and the point cooling part 14a, and between the thick-side main flat surface 15a and the cooling part body 9a.
You may make it intervene both between 6a.

Further, the cooling part 9a is provided with a flow path 17a for flowing cooling water, and the flow path 17a is provided at a predetermined cooling time.
A cooling action is generated in the cooling unit 9a by flowing cooling water to the cooling unit 9a. Further, other cooling fluid such as cooling air can be used for the flow path 17a.

On the other hand, as shown in FIG. 3, the shapes of the cooling unit 9b and the insert 8b according to the present invention are also proposed. In the structure of FIG. 3, since the thin portion 10 of the insert 8b is wider than that of the structure of FIG. 2, the pressure contact surface between the thin-side partial flat surface 11b and the point cooling portion 14b is wide, and the gate 51 and the spoke portion 52 are wide.
The effect of cooling the hub portion 54 between and can be further improved. Further, in such a structure, when the die 1 is processed, the processing of the insert 8b is relatively easy, so that it is possible to suppress a rise in die processing cost.

Next, the casting process in the present invention will be described with reference to a concrete example using FIGS. 1 and 2. As a material for automobile wheels, for example, an aluminum alloy is melted by heating in a melting furnace or the like to form a molten metal. The molten aluminum, which has been heated to a high temperature of about 700 ° C., is poured from the gate 51 of the automobile wheel casting mold 1. The molten metal flows into the cavity 5, passes through the spokes 52 from the hub 54, reaches the rim 53, is filled from the end of the rim 53, and reaches the end of the rim 53. The temperature gradually decreases,
The progress of coagulation begins. Generally, a metal material such as an aluminum alloy undergoes heat shrinkage deformation upon cooling, and thus cracks, defects, and the like are likely to occur in the aluminum alloy. for that reason,
The molten metal is injected from the gate 51 at a predetermined pressure, and the molten metal is replenished so that the product has a desired shape.

As the molten metal flows in in this way, the mold is heated to a high temperature by the molten metal, and in particular, the gate 5 of the insert 8a.
In the vicinity of 1, it becomes a high temperature of about 400 ° C to 500 ° C. In order to cool the insert 8a that has reached a high temperature, in the cooling part 9a, the entire cooling part 16a contacts the thick side main plane 15a to cool the entire insert 8a, and the point cooling part 14a expands and contracts by heat. The sprue 51 and the hub portion 54 of the spoke portion 52 are locally forcedly cooled by pressure contact with the thin-side partial flat surface 11a via the cushioning material 13 (graphite sheet member). This makes it possible to cool the thick hub portion 54 faster than the thin sprue 51 while increasing the cooling speed of the entire wheel.
As a result, it is possible to solidify from the outermost end of the rim portion 53 toward the sprue 51 as sequentially as possible. Therefore, it is possible to cast a sound product without defects by rapidly solidifying while replenishing the molten metal with respect to the heat shrinkage of the aluminum alloy.

Further, as described above, the hub portion 54 having a large wall thickness
By locally forcibly cooling, the internal / external difference in the degree of solidification that occurs in the thickness direction can be reduced, so that an effect of preventing internal defects that are likely to occur when the thick portion is cooled can also be obtained.

In such a cooling process, the temperature of the cooling member 9a is about 100 ° C. and the temperature of the insert 8a is about 400 during cooling.
C. to 500.degree. C., the heat conduction between the two causes the cooling section body 9a and the insert 8a to expand and contract thermally, and the point cooling section 1
In 4a, the contraction deformation of the cooling unit 9a becomes large due to the difference in the heat contraction deformation action. In order to prevent the generation of space due to this, the thermal expansion / shrinkage cushioning material 13 as described above is interposed. The thermal expansion / shrinkage cushioning material 13 is used for the insert 8 at room temperature.
Since the cooling portion body 9a is in a compression deformation state by being pressed against a, even if the insert 8a and the cooling portion body 9a are separated due to the thermal expansion / contraction deformation of the point cooling portion 14, the thermal expansion is caused by the deformation. Only the compressive deformation of the shrinkage cushioning material 13 is alleviated, and the shrinkage cushioning material 13 can be kept in contact with both the insert 8a and the cooling section body 9a, so that heat conduction between them can be properly performed.

On the other hand, in the mold 1 having the conventional cooling section body 9'as shown in FIG. 4 (the same reference numerals are used for common parts), the entire cooling section 16 'of the cooling section body 9'is provided. Is in contact with the thick-walled main plane 15 ', thereby cooling the insert 8'as a whole, so that the spokes 52 and the sprue 51, which have a relatively thin shape, cool faster. The cooling rate of the hub portion 54 having a thick shape is the same as the spoke portion 52.
It becomes dull compared to the end of the gate 51. Therefore, as described above, the sprue 51 is cooled faster than the hub portion 54 and solidifies, and it becomes difficult to replenish the molten metal to the hub portion 54. Therefore, defects or the like are likely to occur due to heat shrinkage, and This can cause a decrease in efficiency.

Further, a mold 1 provided with a cooling part body 9 "of a comparative example shown in FIG. 5 (the same reference numerals are used for common parts).
Since the thermal expansion / shrinkage cushioning material 13 is not used between the thin-side partial flat surface 11 ″ of the insert 8 ″ and the point cooling part 14 ″ of the cooling part 9 ″, the insert 8 ″ and the cooling part In anticipation of thermal expansion / contraction deformation caused by heat conduction with the body 9 ", the escape space 18 is previously formed in the thick side main plane 15" and the entire cooling unit 1
6 ". Generally, the thermal conductivity of air is low, so that the thermal conduction of the escape space 18 becomes insufficient, and the necessary cooling action may not be obtained.

As described above, according to the present invention, in the cooling process of the automobile wheel, the entire cooling unit 16 of the cooling unit 9a is used.
The entire insert 8a is cooled by a, and the point cooling unit 14
Since the hub portion 54 is forcibly cooled by a, the occurrence of defects can be prevented. Further, by interposing the thermal expansion / contraction cushioning material 13 between the point cooling part 14a of the cooling part 9a and the thin side partial flat surface 11a of the insert 8a, the point cooling part 14a and the thin side partial flat surface due to thermal expansion / contraction. Since it is possible to prevent the generation of a space between 11a and to eliminate the need to provide the escape space 18 in anticipation of thermal expansion / contraction deformation, it is possible to perform a proper cooling action on the insert 8a. The present invention is not limited to this embodiment, and can be implemented in various forms without departing from the scope of the present invention, and can be appropriately implemented in manufacturing other than automobile wheels.

[0029]

As described above, according to the present invention, as the cooling unit for the automobile wheel, the entire cooling unit for cooling the entire insert and the point cooling unit for forcibly cooling the hub unit are provided, so that the entire cooling unit can be used for the automobile. While the wheel cooling rate is generally increased, the point cooling section can locally and forcibly cool the hub section according to the cooling rate, so that an appropriate cooling effect can be produced as a whole, and the molten metal Since a process in which the solidification of (1) progresses sequentially from the outermost end of the rim toward the sprue, defects and the like can be prevented and a sound automobile wheel product can be efficiently manufactured.

By interposing a thermal expansion / contraction cushioning material in either or both of the overall cooling part and the point cooling part of the cooling part body which is in contact with the insert, the contact part between the cooling part and the insert due to thermal expansion / contraction deformation. Since it is possible to prevent the occurrence of a space in the space and it is not necessary to provide an escape space in advance in anticipation of the thermal expansion / contraction deformation, an appropriate cooling effect can always be obtained.

A high cooling effect and durability can be obtained by using a sheet member made of graphite as an elastic body having excellent thermal conductivity and high heat resistance for the thermal expansion / shrinkage buffer material.

[Brief description of drawings]

FIG. 1 is a sectional view of an automobile wheel mold 1 of the present invention.

FIG. 2 is a specific example of an insert 8a and a cooling unit 9a according to the present invention.

FIG. 3 is a specific example of the insert 8b and the cooling unit 9b according to the present invention.

FIG. 4 is an example of a conventional insert 8'and a cooling body 9 '.

FIG. 5 is a relief space 18 between the insert 8 ″ and the cooling body 9 ″.
It is a comparative example in which is set.

[Explanation of symbols]

1 mold 8a, 8b nesting 9a, 9b Cooling body 11a, 11b Partial plane of thin side 13 Thermal expansion / shrinkage buffer material 14a, 14b Point cooling unit 15a, 15b thick main surface 16a, 16b Whole cooling unit

Claims (3)

[Claims] 1. A spoke having a thick portion formed by forming a thin portion on a sprue side of a spoke portion forming runway, a surface facing the spoke portion forming runway being a thin side partial flat surface, and further excluding the thin portion. Part that defines the cavity of an automobile wheel mold whose surface facing the molding hot runway is the thick side main plane, the entire cooling section that contacts the thick side main plane, and the thin side partial plane And a cooling part body including a point cooling part, and a thermal expansion / shrinkage buffer material is interposed between the point cooling part and the thin-side partial plane surface and / or between the entire cooling part and the thick-side main plane surface. A casting device for automobile wheels, which is characterized in that 2. The casting device for a wheel for an automobile according to claim 1, wherein the thermal expansion / shrinkage buffer material is an elastic body having both high thermal conductivity and heat resistance. 3. The automobile wheel casting apparatus according to claim 1, wherein the thermal expansion / shrinkage buffer material is a sheet member made of graphite.