JP2017006980A - Casting mold, and light alloy wheel manufacturing method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a casing mold for manufacturing a light alloy wheel reduced in a casting defect such as a shrinkage cavity to be formed in a rim part, and a processing method using the casting mold.SOLUTION: A casting mold comprises: an upper die; a lower die arranged to oppose the upper die; and a horizontal die arranged laterally of the upper die and the lower die. The horizontal die is formed with two sprues opened in a cavity shaping a rim part such that the two sprues are opposed to each other through the center line of the cavity shaping the rim part. The upper die is formed with an internal space for supplying a coolant. The upper die is formed with a bottom wall for defining the bottom of the internal space. The casting mold is characterized in that the bottom wall has an inner face facing the internal space, and in that the height of the inner face in a vertical direction with reference to the lower end of the cavity defining the rim part is low at the intermediate part of the two sprues and higher on the sprue sides than at an intermediate part.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a casting mold for producing a light alloy wheel formed of a light alloy such as an aluminum alloy and a method for producing a light alloy wheel using the same.

  As a light alloy wheel for a vehicle mounted on an automobile (passenger car or the like), an aluminum wheel formed entirely of an aluminum alloy by a technique such as low pressure casting is used in order to reduce the weight of the vehicle body.

  Light alloy wheels manufactured by a casting method are required to have few casting defects such as shrinkage cavities. Patent Document 1 discloses an example of such a manufacturing method. FIG. 8 shows a casting method described in Patent Document 1. When an upper mold of a side gate type mold apparatus provided with an upper mold, a lower mold, and a pair of horizontal molds is viewed from above, the internal structure of the upper mold is schematically illustrated. FIG. The air-cooling pipe 324 shown in FIG. 8 is for air-cooling the front dam portion S of the rim cavity CR. On the other hand, the misfire cooling means 325 mist cools the portion A of the rim cavity CR. This portion A is a portion of the cylindrical rim cavity CR that is shifted by 90 ° in the circumferential direction of the rim cavity CR from the front dam portion S connected to the dam forming space 331. This is the farthest part in the circumferential direction of the cavity CR.

JP 2008-155235 A (paragraph 0044, FIGS. 1 and 3)

  In the conventional casting method disclosed in Patent Document 1 as an example, there is a case where the suppression of the shrinkage nest at the intersecting portion where the rim portion and the disc portion of the light alloy wheel intersect is insufficient. Therefore, there is a demand for a casting mold capable of producing a light alloy wheel with high strength and reduced air leakage, and a method for producing a light alloy wheel using the same, with respect to the prior art, with reduced shrinkage at the intersection. It had been.

  Accordingly, an object of the present invention is to reduce the casting defects such as shrinkage cavities generated at the intersections, and to provide a casting mold for producing a light alloy wheel with high strength and suppressed air leakage, as compared with the prior art. It is to provide a manufacturing method using

  The casting mold according to the first invention of the present application is used for manufacturing a light alloy wheel having a substantially cylindrical rim portion and a disc portion installed in the rim portion to which an axle is mounted. A casting mold having an upper mold, a lower mold disposed to face the upper mold, and a horizontal mold disposed on a side of the upper mold and the lower mold. Among the cavities that are formed by matching the lower mold and the horizontal mold and that are shaped like the light alloy wheel, the cavity that has a substantially cylindrical shape that looks like the rim portion is arranged in a posture in which the center line is set up. The horizontal mold is formed such that two gates that open to the cavity that represents the rim portion are opposed to each other via the center line of the cavity that represents the rim portion. An internal space for supplying is formed, and the upper mold is A bottom wall defining a bottom portion in between, the bottom wall having an inner surface facing the inner space, and the height of the inner surface in the vertical direction with respect to the lower end of the cavity that represents the rim portion is In the direction, it is characterized in that it is low at the middle part of the two gates and is higher at the gate side than the intermediate part.

  1st invention of this application WHEREIN: The structure where the inner surface of the said intermediate part and the inner surface of the pouring gate side rather than the said intermediate part continue in a step shape is employable.

  1st invention of this application WHEREIN: It is preferable that the range of the said intermediate part in the circumferential direction is 20 degrees-70 degrees centering | focusing on the intermediate point of said two gates, and it is still more preferable that it is 30 degrees-60 degrees.

  A method for manufacturing a light alloy wheel according to a second invention of the present application is a method of injecting a molten metal made of a light alloy into a cavity that represents the light alloy wheel of a casting mold according to the first invention of the present application, and providing the upper mold with the molten metal. The coolant is supplied to the inner space to cool the molten metal injected into the cavity that represents the rim.

  The light alloy wheel manufacturing method according to the present invention is a casting method for manufacturing a light alloy wheel in which casting defects such as shrinkage cavities generated at intersections are reduced and air leakage is suppressed with respect to the prior art. And a light alloy wheel manufacturing method using the same.

It is a longitudinal cross-sectional view (B'-IB sectional drawing of FIG. 2) which shows an example of the casting die used in order to manufacture the light alloy wheel which concerns on embodiment of this invention. It is AA sectional drawing of FIG. FIG. 3 is a DD arrow view of FIG. 2. FIG. 3 is a partial cross-sectional view taken along the line IB in FIG. 2 and a partial cross-sectional view taken along the line IE in FIG. It is a figure which shows the progress state of solidification of the molten metal cast in the cavity for rim | limb parts. It is a top view which shows an example of a light alloy wheel. It is JJ sectional drawing of the light alloy wheel of FIG. It is a top view of the casting_mold | template apparatus for enforcing the manufacturing method of the conventional light alloy wheel.

  The present invention will be described based on specific embodiments with reference to the drawings. It should be noted that the present invention is not limited to the embodiments described below, and can be appropriately modified and implemented within the range of the same as long as the effects of the invention are exhibited.

  The inventors have made the height of the inner surface of the upper mold bottom wall in the vertical direction with respect to the lower end of the cavity representing the rim portion lower in the middle portion between the two gates in the circumferential direction and lower than the middle portion. The inventors have found that the above object can be achieved by producing a light alloy wheel using a casting mold raised on the side, and have arrived at the present invention. The detailed configuration of the upper mold will be described later.

  Hereinafter, a light alloy wheel manufacturing method according to an embodiment of the present invention will be described in detail with reference to FIGS.

[Configuration of light alloy wheel]
The structure of the light alloy wheel according to the embodiment of the present invention will be described by taking an aluminum wheel as an example with reference to FIGS. FIG. 6 is a bottom view of the aluminum wheel (hereinafter sometimes referred to as a wheel) 10 of FIG. 7 is a cross-sectional view taken along line JJ in FIG. The direction of the center line I of the wheel 10 shown in FIG. 7 may be referred to as the axial direction, the direction orthogonal to the center line I may be referred to as the radial direction, and the direction around the center line I may be referred to as the circumferential direction. As shown in FIGS. 6 and 7, the wheel 10 has a disk portion 9e having a hub portion 9f and a design portion 9g formed radially from the outer peripheral surface of the hub portion 9f. The wheel 10 includes a rim main body portion 9b in which the outer peripheral portion of the disk portion 9e is coupled to the inner peripheral surface, and a first flange portion (a so-called outer flange portion) disposed at the lower (one) end of the rim main body portion 9b. ) 9c and a substantially cylindrical rim portion 9a having a second flange portion (so-called inner flange portion) 9d disposed at the upper (other) end. The rim portion 9a is coupled to the disc portion 9e on the first flange portion 9c side, and the portion of the disc portion 9e that is coupled to the rim portion 9a is the intersecting portion 26. Moreover, although the form of the design part 9g of this embodiment is a spoke type, the form of a design part is not limited to this, For example, it can be set as a mesh type and other various forms. In this wheel 10, after the tire is attached to the rim body 9b so as to be sandwiched between the first flange portion 9c and the second flange portion 9d, the disc portion 9e faces the outside of the vehicle body. Attach it to the axle and use it.

[Casting mold]
An example of a casting mold for manufacturing the wheel having the above-described configuration will be described with reference to FIGS. Here, FIG. 1 is a longitudinal sectional view along the axial direction of a casting mold 100 incorporated in a casting apparatus for low pressure casting of the spoke type aluminum wheel (B′-IB sectional view of FIG. 2). It is. FIG. 2 is a cross-sectional view taken along the line AA in the radial direction of the casting mold 100 of FIG. 3 is a DD partial arrow view of the upper mold 13 in the circumferential direction of the casting mold 100 of FIG. 4 is a partial cross-sectional view taken along line IB in FIG. 2 (a) and a partial cross-sectional view taken along line IE in FIG. In FIG. 2, which is a cross-sectional view taken along the line AA of FIG.

  As shown in FIG. 1, a casting mold (hereinafter sometimes referred to as a mold) 100 includes an upper mold 13, a lower mold 12, an upper mold 13, and a lower mold disposed so as to face the upper mold 13. It has a horizontal mold 14 which is a pair of movable split molds arranged on the side of the mold 12. A wheel material (hereinafter referred to as a wheel including this wheel material) in which an appropriate surplus (for example, machining allowance) is added to the wheel 10 as necessary by clamping and mold-matching each die. An imaged cavity is formed. That is, as shown in FIGS. 1 and 2, a cavity 100a in which the disk portion 9e is formed (hereinafter sometimes referred to as a disk portion cavity; the same applies to cavities in other portions) 100a and a rim portion 9a are formed. A rim cavity 100b is formed. In the present embodiment, the rim cavity 100b is arranged in a posture in which the center line I is set up. The mold 100 has a gate (hereinafter also referred to as a center gate) 18 that opens into the hub cavity 21a, and two hot water that opens into the rim body cavity 23a of the rim cavity 100b. B (hereinafter sometimes referred to as a side gate) 19 is formed, and the center gate 18 and the side gate 19 are connected to stalks 15 and 16 which are runners, respectively. In carrying out the present invention, the center gate 18 opened to the hub cavity 21a is not essential, and may be provided as necessary.

  As shown in FIG. 2, the horizontal mold of the mold 100 according to the present embodiment is composed of two horizontal molds divided through a center line I. The two side gates 19 that open to the rim cavity are formed on the die mating surfaces of the two horizontal dies 14 that are clamped. In other words, the two side gates 19 are formed so as to face each other via the center line of the cavity that represents the rim portion. In addition, although the horizontal type | mold 14 of this embodiment is divided into 2 parts, the structure of 3 parts or more may be sufficient.

  FIG. 2 is a sectional view taken along the line AA in FIG. The upper mold 13 has an internal space 131. Here, the cross-sectional shape in the radial direction of the outer periphery of the upper mold 13 of this embodiment is a circular shape. The outer surface 131o of the inner space 131 is formed concentrically with respect to the outer periphery of the upper die 13 in the upper die 13 so that the thickness in the radial direction of the side wall 13c of the upper die 13 is uniform along the circumferential direction. The In addition, the internal space 131 of the present embodiment has an inner surface 131i formed concentrically inside the outer surface 131o and has a ring shape as a whole. The inner surface 131i is not always necessary. For example, the inner surface may not be formed, and may be a cylindrical internal space having only the outer surface 131o. The internal space 131 does not necessarily have an integral structure, and may be formed by being divided in the circumferential direction. For example, in the case of dividing into four, a total of four internal spaces can be formed between each position facing two side gates and between them. An advantage of dividing the internal space is that independent cooling control can be performed in each internal space.

  The internal space 131 is provided with a cooling means 13a. The cooling means 13a is located in the middle of the two side gates 19 in the circumferential direction (centering on the middle point between the two side gates 19 in the circumferential direction). A range of approximately 90 ° (hereinafter, simply referred to as “medium”) is configured to eject the refrigerant (liquid or gas) toward the side wall 13c existing in the middle. The refrigerant jetted to the side wall 13c cools the molten metal filled in the middle of the rim portion cavity 100b through the side wall 13c. Further, the internal space 131 is provided with a cooling means 13b, and the cooling means 13b is configured to eject a refrigerant (liquid or gas) toward the side wall 13c existing in front of and in the vicinity of the side gate 19. Has been. The refrigerant jetted to the side wall 13c cools the molten metal filled in front of and in the vicinity of the side gate 19 of the rim cavity 100b through the side wall 13c.

  The upper mold 13 has bottom walls 131m and 131s that form a disk portion cavity 100a by mold matching with the lower mold 12. The bottom wall 131m is formed in the middle part (hereinafter simply referred to as the middle part) of the two side gates 19 in the circumferential direction, and the bottom wall 131s is formed closer to the side gate 19 than the middle part. The bottom walls 131m and 131s have inner surfaces 131ms and 131ss facing the internal space 131. Then, as shown in FIG. 3 which is an enlarged arrow view of the DD portion of FIG. 2, the inner surfaces 131ms of the upper mold bottom walls 131m, 131s in the vertical direction with respect to the lower end of the rim cavity 100b as a reference. The height of 131 ss (hereinafter sometimes referred to as the height of the inner surface) is such that the inner surface 131 ms of the intermediate portion of the two side game rods 19 is low (illustrated h1) in the circumferential direction, and is closer to the side gate than the intermediate portion. The inner surface 131s is high (illustration h2). Here, the lower end of the rim cavity 100b is a surface 100be that is in contact with the lower mold 12 on the side where the intersecting portion 26 is located in the rim cavity 100b that is arranged in a posture in which the center line I is erected. Point to. In addition, as shown in FIG. 3, it is preferable that the inner surface 131ms of the intermediate portion and the inner surface 131ss on the side gate 19 side of the intermediate portion are connected in a stepped manner.

  The range θ in the circumferential direction of the intermediate portion where the low inner surface 131 ms is disposed as described above is preferably 20 ° to 70 °, and is preferably 30 ° to 60 °, centering on the intermediate point of the two side gates 19. More preferably. This is because if it is less than 20 ° or more than 70 °, the effect of reducing casting defects such as shrinkage cavities generated in the rim portion is slightly reduced.

  When a light alloy wheel is manufactured by a casting method in which a molten metal is injected from the side gate 19 that opens to the rim cavity 100b, the molten metal filled in the rim cavity 100b is moved from the position farthest from the side gate 19. It is known that it is preferable to solidify along the circumferential direction toward the side gate 19 (hereinafter, this solidification form may be referred to as circumferential-directional solidification). A portion of the rim portion cavity 100b close to the disk portion cavity 100a (hereinafter sometimes referred to as a rim portion lower cavity) is dotted with the intersecting portions 26 that easily form an unsolidified closed loop. It was difficult to achieve circumferential directional solidification in this part. In particular, in the circumferential direction, when the intersection 26 exists at a position farthest from the side gate 19 and 90 ° away from the side gate 19, not only can the circumferential direction solidification be achieved, but also the pushing from the side gate 19 can be achieved. The hot water effect was insufficient, and casting defects such as shrinkage could occur at the intersections.

FIG. 4 shows a partial cross-sectional view taken along the line IB of FIG. 2 and a partial cross-sectional view taken along the line IE of FIG. In the present invention, the circumferential compared to the height _{h 1} of the inner surface 131ms of the bottom wall 131m of the middle portion of the two side gates 19 in the direction, with respect to the bottom wall 131m of the middle portion of the side gate 19 side of the bottom wall 131s since was higher position the height h ₂ of the inner surface 131Ss, middle portion of the bottom wall 131m molten metal of the rim portion lower cavity 100bd the corresponding position on the side wall of the upper mold 13 for (hereinafter, referred to as intermediate rim under melt.) Compared to the heat removal ability (thick arrow) by 13c, the upper mold 13 for the molten metal in the rim portion lower cavity 100bd at the position corresponding to the bottom wall 131s on the side gate 19 side (hereinafter referred to as the side gate side rim lower molten metal). The heat removal ability (thin arrow) by the side wall 13c of the steel plate is relatively lowered. The height h ₁ of the inner surface 131 ms is preferably equal to or lower than the height of the intersecting portion 26, and the height h ₂ of the inner surface 131 ss preferably exceeds the height of the intersecting portion 26. Therefore, the relationship of h ₁ <h ₂ is established. The ratio of the liquid phase of the side gate side rim lower molten metal is always larger than the ratio of the liquid phase of the intermediate rim lower molten metal until the solidification is completed after the rim cavity 100b is filled with the molten metal. Therefore, the effect of the hot water on the molten rim under the rim through the side gate side molten rim is maintained. As a result, circumferential direction-directed solidification can be achieved also in the rim portion lower cavity 100bd, and casting defects such as shrinkage cavities generated at the intersection can be reduced.

[Production method of light alloy wheel]
Next, a method for manufacturing a light alloy wheel using the mold 100 having the above-described configuration will be described. First, the lower mold 12, the upper mold 13 and the horizontal mold 14 in FIG. 1 are clamped to form a cavity. Next, a molten metal pressurized and stored in a holding furnace (not shown) installed under the mold 100 is a cavity that looks like a wheel from the center gate 18 and the side gate 19 via the stalks 15 and 16. It inject | pours into the cavity 100a for disc parts, and the cavity 100b for rim | limb parts. Then, after the molten aluminum alloy is filled up to the inner flange cavity 25a, which is the upper end of the rim cavity 100b, pressurization in the holding furnace is maintained for a predetermined time (a pouring process).

  After the molten metal is filled up to the inner flange cavity 25a in the pouring step, the cooling air is circulated through the cooling pipes (cooling means) 13a and 13b and ejected, whereby the molten aluminum alloy injected into the rim cavity 100b is injected. A cooling process is performed. By cooling the molten aluminum alloy filled to increase the solidification rate, the solidified structure becomes finer, and the wheel strength can be improved.

  With reference to FIG. 5, a description will be given of the circumferential directional solidification of the molten metal filled in the rim cavity 100 b achieved by the mold 100 and the manufacturing method of the above aspect. FIG. 5 is a diagram conceptually showing the solidification process of the molten metal in the cooling process. In FIGS. 1 and 2, the disk portion cavity 100a, the rib portion cavity 100b, the center gate 18 and the side gate 19 are filled. 5 is a perspective sectional view showing only the molten metal, and illustration of each component of the manufacturing apparatus such as the upper mold 13 and the lower mold 12 is omitted for the sake of understanding. Moreover, the two-dot chain line shown with the code | symbol R1-R7 in FIG. 5 has shown the distribution of the solidus line when a molten metal solidifies in a contour line. Specifically, each of the lines R1 to R7 is a line connecting points where the molten metal reaches the solid phase line at approximately the same time in the cooling process after the filling of the molten metal into the rim cavity 100b is completed.

  In the mold 100 having the cooling means 13a and 13b having the above configuration, the molten metal filled in the rim cavity 100b through the side gate 19 is solidified in the form described below. That is, when the mold 100 of this aspect is used, the solidification of the molten metal filled in the rim portion cavity 100b is present at a position farthest from the side gate 19 and from a position in contact with the side wall of the upper mold 13. Start. In the case of the present embodiment, the cavity for the inner flange portion disposed in the middle portion of the pair of side gates 19 (position 90 ° away from the side gates 19) in the circumferential direction and disposed above in the axial direction. Solidification of the melt starts from point Q of 25a.

  Furthermore, in the present invention, the bottom wall 131s on the side gate 19 side of the intermediate gate wall 131m is compared with the height of the inner surface 131ms of the intermediate wall 131m of the intermediate wall between the two side gates 19 in the circumferential direction. The rim at a position corresponding to the bottom wall 131s on the side of the side gate 19 as compared with the heat removal ability of the lower rim cavity at the position corresponding to the bottom wall 131m at the middle portion with the height of the inner surface 131ss being higher. Since the heat removal capability of the lower part cavity relative to the molten metal is relatively lowered, the molten metal that has started to solidify from the point Q moves from the line R1 to the line R7 as indicated by arrows P1 to P3, and the inner flange cavity 25a As the solidification progresses downward from the side gate 19 to the side gate 19, the solidification in the circumferential direction becomes clearer. Thus, in the metal mold | die which concerns on this invention, and a manufacturing method using the same, desired circumferential direction directional solidification toward the side gate 19 from the position (point Q) most distant from the side gate 19 can be achieved. .

  After the above cooling process is completed, pressurization in the holding furnace is stopped, the molten metal is returned to the holding furnace, the solidified wheel material is taken out from the mold 100, and this wheel material is appropriately processed or painted as necessary. A desired wheel can be obtained by performing an appropriate process.

10 Aluminum wheel 9a Rim part 9b Rim body part 9c First flange part (outer flange part)
9d Second flange (inner flange)
9e Disk part 9g Design part 12 Lower mold 13 Upper mold 13a, 13b Cooling pipe (cooling means)
13c Side wall 14 Horizontal type 18 Center gate (gate)
19 Side game bowl (Yuguchi)
100 casting mold 100a disk part cavity 100b rim part cavity 100bd rim part lower cavity 23a rim body part cavity 24a first flange part cavity 25a second flange part cavity 131 inner space 131i inner surface of inner space 131o Outer surface 131m of the inner space Bottom wall 131ms of the inner space of the middle part of the two side game boxes 131ms Inner surface 131s of the inner wall of the inner space of the middle part of the two side game lamps 131ss The inner surface θ of the bottom wall of the internal space on the side of the side game board relative to the middle part The range of the bottom wall of the middle part

Claims (4)

A casting mold used for producing a light alloy wheel having a substantially cylindrical rim portion and a disk portion mounted on the rim portion and mounted with an axle,
An upper mold, a lower mold disposed to face the upper mold, and a horizontal mold disposed on a side of the upper mold and the lower mold,
Of the cavities that are formed by matching the upper mold, the lower mold, and the horizontal mold and that are shaped like the light alloy wheel, the cavity that has a substantially cylindrical shape that looks like the rim portion has its center line set up. Arranged in a posture,
The horizontal mold is formed such that two gates that open to a cavity that models the rim portion are opposed to each other via a center line of the cavity that models the rim portion,
The upper mold is formed with an internal space for supplying a refrigerant,
The upper mold has a bottom wall that defines a bottom portion of the internal space, and the bottom wall has an inner surface facing the internal space;
The height of the inner surface in the vertical direction with respect to the lower end of the cavity representing the rim portion is lower in the middle portion between the two gates in the circumferential direction and higher on the gate side than the intermediate portion. Mold for casting.   The casting mold according to claim 1, wherein the inner surface of the intermediate portion and the inner surface on the side of the pouring gate with respect to the intermediate portion are connected stepwise.   The casting mold according to claim 1 or 2, wherein a range of the intermediate portion in the circumferential direction is 20 ° to 70 ° centering on an intermediate point between the two gates.   The molten metal made of a light alloy is injected into a cavity representing the light alloy wheel of the casting mold according to any one of claims 1 to 3, and a coolant is supplied to an internal space provided in the upper mold to thereby form the rim. A method of manufacturing a light alloy wheel, characterized by cooling a molten metal injected into a cavity that represents a part.

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