JP2007125572A - Casting die - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the generation of casting defects in the case a casting having a cylindrical part is cast by the charge of molten metal from a side gate. <P>SOLUTION: The die of casting a wheel for a vehicle comprises: a disk part forming space; and a rim part forming space 20b (cylindrical part forming space) connected to the periphery of the disk part forming space and elongating from the periphery to the upper part. A side part runner is connected to the rim part forming space 20b, and the opening edge of the side part runner to the rim part forming space 20b forms a side gate 25x. When the runner part 25b in the vicinity of the side gate 25x in the side part runner is tilted to the normal of the circumferential face in the rim part forming space 20b when being observed from the upper part, and the crossing angle Θ between the runner part 25b and the normal N on the circumferential face of the rim part forming space 20b is 5 to 30°. The lower face 25L of the runner part 25b is tilted so as to lower toward the rim forming space 20b, and the boundary between the same and the outer circumferential face of the rim forming space 20b is R-chamfered. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a mold for a cast product having a cylindrical portion.

  Patent Document 1 discloses a low pressure casting apparatus that casts a vehicle wheel made of aluminum alloy (made of light alloy). The mold of this apparatus has a disk part forming space and a rim part forming space (cylinder part forming space). The ends of the plurality of side runners of the mold are opened to the peripheral surface of the rim forming space to form side gates.

During casting, the molten metal passes through the side runner and is supplied from the side gate to the rim portion forming space.
JP 2001-300716 A

  In the metal mold of Patent Document 1, the molten metal poured from the side gate through the side runner flows down into the molten metal pool in the disk part molding space or the molten metal pool in the rim part molding space. Thus, when the molten metal flows down to the molten metal pool, a gas such as air in the molding space is entrained and enters into the molten metal bubble as a bubble, which causes casting defects such as nests in the cast product. May occur.

  The inventor has analyzed the above phenomenon in detail. The analysis will be described with reference to FIGS. FIG. 6 is a transverse cross-sectional view of a mold similar to that of Patent Document 1, and a runner portion in the vicinity of the side gate 25x in the side runner is indicated by reference numeral 25b. The runner portion 25b is orthogonal to the outer peripheral surface of the cylindrical rim forming space 20b. In other words, the runner portion 25b extends along a line L 'passing through the central axis 20x of the rim portion forming space 20b.

  Due to the above-described configuration, as shown in FIG. 7, the molten metal poured from the side gate 25x through the runner portion 25b of the side runner vertically flows down in the rim portion forming space 20b. It is not easy for the bubbles K entrained in the flow-down process to be taken into the vortex generated in the molten metal reservoir Y ′ and escape from the molten metal reservoir Y ′. As a result, the above inconvenience occurs.

  In order to solve the above-mentioned problems, the present invention includes a cylindrical part forming space whose central axis extends in the vertical direction, and a side runner connected to the cylindrical part forming space, to the cylindrical part forming space of the side runner. In the casting mold in which the open end of the side portion is a side gate, the runner portion in the vicinity of the side gate in the side runner is inclined with respect to the normal of the peripheral surface of the cylindrical portion forming space when viewed from above. It is characterized by.

  According to the said structure, since the flow of the molten metal from a side gate has the vector of the circumferential direction, the bubble caught in the molten metal pool can be escaped favorably, and generation | occurrence | production of casting defects, such as a nest, can be suppressed.

  Preferably, the intersection angle between the runner portion near the side gate and the normal line of the peripheral surface of the cylindrical portion forming space is 5 to 30 °. This is because if the angle is less than 5 °, the above effect is reduced, and if it exceeds 30 °, the strength of the mold is reduced and the cost for manufacturing the mold is increased.

  Preferably, at least a lower surface of the runner portion in the vicinity of the side gate is inclined so as to be lowered toward the cylindrical portion forming space. According to this configuration, the molten metal flowing out from the side gate has little change in the direction of the flow when the molten metal flows from the runway to the side gate and the cylindrical part molding space, and the flow is less disturbed, thereby suppressing the entrainment of bubbles. To do. Therefore, the occurrence of casting defects can be further suppressed.

  Preferably, the boundary between the lower surface of the runner portion and the outer peripheral surface of the cylindrical portion forming space is rounded. According to this configuration, the molten metal flowing out from the side gate to the cylindrical portion forming space easily flows along the outer peripheral surface of the cylindrical portion forming space, and the flow of the molten metal becomes difficult to peel off from the outer peripheral surface of the cylindrical portion forming space. Suppresses entrainment. Therefore, the occurrence of casting defects can be further suppressed.

  Preferably, it is for casting a vehicle wheel, and has a disk part forming space and a rim part forming space that is continuous with the periphery of the disk part forming space and extends upward and downward from the periphery. A part forming space is provided as the cylindrical part forming space. Thereby, a high quality vehicle wheel can be cast.

  According to the present invention, it is possible to improve the quality of a cast product having a cylindrical portion.

  Hereinafter, a low pressure casting apparatus for a vehicle wheel (casting product) made of aluminum alloy (made of light alloy), which constitutes a first embodiment of the present invention, will be described with reference to FIGS. As is well known, the vehicle wheel has a disk portion and a rim portion (cylindrical cylindrical portion) formed integrally with the periphery of the disk portion.

  As shown in FIG. 1, the low-pressure casting apparatus includes a mold 10 and a molten metal holding furnace installed below the mold 10 as basic components.

  As shown in FIGS. 1 and 2, the mold 10 is divided into a lower mold 11 fixed at a predetermined position, an upper mold 12 that is positioned directly above the lower mold 11 and moves up and down, and is divided into a plurality in the circumferential direction. The horizontal mold 13 is provided. In these drawings, the dividing surface of the horizontal mold 13 is omitted.

  As shown in FIG. 1, when the mold 10 is clamped, a wheel forming space 20 for casting a vehicle wheel is formed therein.

  The wheel forming space 20 has a disk part forming space 20a and a cylindrical rim part forming space 20b (cylinder part forming space) connected to the periphery thereof. A central axis 20x of the rim portion forming space 20b extends vertically through the center of the disc portion forming space 20a.

  A plurality of side runners 25 are formed between the side surfaces of the adjacent horizontal molds 13. In the present embodiment, the horizontal mold 13 is divided into three, and three side runners 25 are formed at equal intervals in the circumferential direction.

  The side runner 25 includes a first runner portion 25a that extends vertically, and a second runner portion 25b that extends in the radial direction and inward direction of the mold 10 from the upper end of the first runner portion 25a. Yes. In the present embodiment, the upper surface 25U of the second runner portion 25b extends horizontally, and the lower surface 25L of the second runner portion 25b is inclined so as to descend inward, that is, toward the rim portion forming space 20b. ing.

  An upper end of a stalk (not shown) is connected to a base for fixing the mold 10, and is connected to a lower end of the first runner portion 25a. This stalk extends vertically downward, and its lower end is immersed in a molten metal in a melting and holding furnace (not shown).

  The distal end of the second runner portion 25b is separated from the disk portion forming space 20a, opens to the outer peripheral surface of the rim portion forming space 20b, and serves as a side gate 25x. Therefore, the second runner portion 25b is a runner portion near the side gate 25x.

  The boundary between the lower surface 25L of the second runner portion 25b and the outer peripheral surface of the rim portion molding space 20b is rounded. This round chamfer is indicated by reference numeral 25R in the figure.

  As shown in FIG. 2, the second runner portion 25b of the side runner 25 is inclined with respect to the normal line of the outer peripheral surface of the rim portion molding space 20b when viewed from above. That is, the angle formed by the normal line N of the outer peripheral surface of the rim portion molding space 20b and the line L (line representing the extending direction of the second runner portion 25b) passing through the center in the width direction of the second runner portion 25b is It intersects at a predetermined angle Θ, not zero. This crossing angle Θ is in the range of 5-30 °.

  For reference, in the present embodiment, since the rim portion forming space 20b has a cylindrical shape, the normal N of the outer peripheral surface always passes through the central axis 20x.

  The low-pressure casting method using the apparatus having the above configuration will be described in detail. When the mold 10 is tightened, a pressurized gas such as dry air is supplied to the molten metal holding furnace, and when the molten metal surface is pressurized, the molten metal passes through the stalk and side runner 25, and from the side gate 25x to the rim portion molding space. Poured into 20b.

  The molten metal poured from the side gate 25x flows down the rim portion forming space 20b and is supplied to the disk portion forming space 20a. After filling the disk portion forming space 20a, the rim portion forming space 20b is filled. Thereby, the vehicle wheel is cast.

  As shown in FIG. 3, when the molten metal Y poured from the side gate 25x flows down into the molten metal pool Y ′ of the disk portion forming space 20a or the rim portion forming space 20b, a gas such as air in the forming space 20 Therefore, bubbles K are generated in the molten metal reservoir Y ′.

  In the present embodiment, since the second runner portion 25b in the vicinity of the side gate 25x is inclined with respect to the normal line of the peripheral surface of the rim portion forming space 20b, the molten metal passes through the second runner portion 25b. The circumferential kinetic energy as shown by arrow A1 is given.

  Therefore, when the molten metal flows down the rim portion forming space 20b, the molten metal flows in an oblique manner as indicated by an arrow A2 including a vector in the circumferential direction, not directly below.

  As a result, a flow including a circumferential vector is generated in the molten metal reservoir Y 'as indicated by an arrow A3. This flow drives the bubbles K that have entered the molten metal Y ′ to a position shifted in the circumferential direction from the flowing position of the molten metal Y, and helps the bubbles K escape from the molten metal pool Y ′.

  As described above, since the bubbles K generated when the molten metal Y flows in can easily escape from the molten metal reservoir Y ′, it is possible to prevent casting defects such as nests from remaining in the rim portion of the cast vehicle wheel.

  Since the intersection angle Θ between the second runner portion 25b and the normal line N is 5 ° or more, the above-described good bubble detachment effect can be ensured. Moreover, since the crossing angle Θ is 30 ° or less, it is possible to avoid a decrease in strength of the mold 10 and an increase in manufacturing cost of the mold 10.

  Further, since the lower surface 25L of the second runner portion 25b is inclined so as to be lowered toward the rim portion forming space 20b, the molten metal flowing out from the side gate 25x is formed from the runner 25b to the side gate 25x and the cylindrical portion. When the molten metal flows into the space 20b, there is little change in the direction of the flow and there is little turbulence in the flow.

  Further, since the boundary between the lower surface 25L of the second runner portion 25b and the outer peripheral surface of the rim portion molding space 20b is rounded (see reference numeral 25R), the molten metal that has flowed out from the side gate 25x to the rim portion molding space 20b. However, it is easy to flow along the outer peripheral surface of the rim molding space 20b, and the flow of the molten metal becomes difficult to peel off from the outer peripheral surface of the rim portion molding space 20b, and as a result, entrainment of bubbles can be suppressed.

  Hereinafter, other embodiments of the present invention will be described. In these embodiments, components corresponding to the preceding embodiments are assigned the same reference numerals and detailed description thereof is omitted.

  In the second embodiment shown in FIG. 4, the upper surface 25U of the second runner portion 25b is also inclined so as to go down toward the rim portion forming space 20b in the same manner as the lower surface 25L. Is inclined. According to this, entrainment of bubbles can be further suppressed. Other configurations are the same as those of the first embodiment.

  In the first and second embodiments, a central runner may be formed at the center of the lower mold 11. This central runner extends vertically, and the upper end of the stalk is connected to the lower end thereof. The lower end of this stalk is immersed in the molten metal in the molten metal holding furnace. The upper end of the central runner opens to the center of the lower surface of the disk part forming space 20a to form a center gate. When the pressurized gas is supplied into the molten metal holding furnace, the molten metal is supplied from the center gate to the disk portion forming space 20a through the stalk and the central runner.

  In 3rd Embodiment of FIG. 5, the plane cross section of the cylinder part formation space 120b has comprised the polygon, for example, the hexagon. The outer peripheral surface of this cylindrical part forming space 120b consists of six flat surfaces, and the second runner portion 25b of the side runner 25 is connected to three selected flat surfaces among them.

  Also in the third embodiment, the line L indicating the extending direction of the second runner portion 25b intersects the normal line N of the flat surface of the tubular portion forming space 120b at a predetermined angle Θ. Moreover, although not shown in figure, the lower surface of the 2nd runner part 25b inclines like 1st Embodiment. As a result, the same effect as the first embodiment can be obtained. Since the operation of the third embodiment including the other configurations and the flow of the molten metal is the same as that of the first embodiment, a detailed description thereof will be omitted.

  In addition, when the cylinder part shaping | molding space 120b has comprised the polygon, the line L showing the extension direction of the 2nd runner part 25b passes along the central axis 120x of the cylinder part shaping | molding space 120b as shown in the figure. There is also.

  The present invention is not limited to the above embodiment, and various forms can be adopted. For example, the upper and lower surfaces of the runner portion near the side gate in the side runner may be horizontal. Moreover, the metal mold | die of this invention is applicable not only to low pressure casting but to high pressure casting.

It is a longitudinal cross-sectional view of the metal mold | die of the low pressure casting apparatus which makes 1st Embodiment of this invention. It is a cross-sectional view of the metal mold | die along the II-II line of FIG. In the same embodiment, it is the schematic which looked at the flow of the molten metal which poured into the rim | limb part shaping | molding space from the side gate through the side runner, ie, the III direction in FIG. FIG. 3 is a view corresponding to FIG. 1 showing a second embodiment of the present invention. FIG. 6 is a view corresponding to FIG. 2 showing a third embodiment of the present invention. It is a cross-sectional view of a conventional casting mold. It is the schematic which looked at the flow of the molten metal in the conventional metal mold | die from the VII direction inside, ie, FIG.

Explanation of symbols

10 Mold 20b Rim part molding space (Cylinder part molding space)
20x Central axis 25 Side runner 25b Second runner (runner near the side gate)
25L Lower surface 25U of the second runner portion Upper surface 25R of the second runner portion Rounded chamfered portion 25x Side gate 120b Cylindrical molding space 120x Central axis N Normal line L Line extending the runner portion Θ Crossing angle

Claims (6)

A casting mold having a cylindrical part forming space whose central axis extends in the vertical direction and a side runner connected to the cylindrical part forming space, and an opening end of the side runner to the cylindrical part forming space serves as a side gate. In
A casting mold characterized in that a runner portion in the vicinity of a side gate in the side runner is inclined with respect to a normal line of a peripheral surface of the cylindrical portion forming space when viewed from above.   2. The casting mold according to claim 1, wherein an intersecting angle between a runner portion near the side gate and a normal line of a peripheral surface of the cylindrical portion forming space is 5 to 30 °.   3. The casting mold according to claim 1, wherein at least a lower surface of a runner portion in the vicinity of the side gate is inclined so as to descend toward the cylindrical portion forming space.   The casting mold according to any one of claims 1 to 3, wherein a boundary between the lower surface of the runner portion and the outer peripheral surface of the cylindrical portion forming space is rounded.   A casting wheel for a vehicle, comprising: a disk portion forming space; and a rim portion forming space that is continuous with the periphery of the disk portion forming space and extends upward and downward from the periphery. Is provided as the cylindrical part forming space. The casting mold according to any one of claims 1 to 4.   The vehicle wheel manufactured with the casting metal mold | die of Claim 5.

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