JP2017001060A - Casting formed part and low pressure casting device for manufacturing this casting formed part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a casting formed part capable of preventing the occurrence of a casting defect even in a thin and complicated shape, and a low pressure casting device for manufacturing this casting formed part.SOLUTION: A casting formed part comprises a bottom part 110, an outer wall part 120 rising from the outer periphery of the bottom part and a shelf part bridged in the outer wall part. This casting formed part has a plurality of casting plan parts 160 formed of a spruce runner of a casting device on an undersurface of the bottom part, and also has a vertical wall 180 for directly connecting the casting plan part and the shelf part. A low pressure casting device manufactures the casting formed part. In the casting formed part, this low pressure casting device has a down gate separately arranged from a cavity and a fan gate for communicating the down gate and the cavity on the lower side of the cavity of a casting mold, and the fan gate is connected to an undersurface of the cavity, and also has an upward inclination toward the cavity from the down gate, and the cavity forms a vertical wall for directly connecting the casting plan part and the shelf part of the casting formed part formed by the fan gate.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a cast molded product and a low-pressure casting apparatus for producing the cast molded product, and more specifically, a cast molded product capable of preventing the occurrence of casting defects even in a thin and complex shape, and The present invention relates to a low pressure casting apparatus for producing a cast product.

  An engine mounted on an automobile has a cylinder head. The cylinder head is a hollow cast product produced by a low pressure casting apparatus.

  In recent years, the thickness of the cylinder head has been set as thin as possible due to the demand for weight reduction of automobile components. However, in the low-pressure casting method (method), the casting performance decreases when the thickness is reduced. Defects are likely to occur.

  In Japanese Patent Application Laid-Open No. 2014-50883 of Patent Document 1, the shape of the fan gate that communicates the gate and the cavity is changed to a fan shape that spreads toward the cavity side, and the cross-sectional area is gradually reduced toward the cavity. A low-pressure casting apparatus is disclosed in which a gate can be connected to the lower part of the side surface of the cavity to enable thinning.

JP 2014-50883 A

  However, the low-pressure casting apparatus described in Patent Document 1 is for producing a suspension member, and is not suitable for molding a thinned cylinder head.

  In other words, the suspension member generally has a simple internal shape and a substantially uniform wall thickness, whereas the cylinder head has a complicated internal shape, a bent filling path, and a non-uniform wall thickness. It is.

  In addition, since the suspension member is large in the horizontal direction, the molten metal flows and is molded in a substantially horizontal direction. However, since the cylinder head has a substantially rectangular parallelepiped shape, the molten metal flows in a substantially vertical direction. Moreover, the gate space under the cavity is limited in the production of the cylinder head.

  As described above, the cylinder head is greatly different from the suspension member in the internal structure, the condition of the hot water supply, and the like, and by making the pouring gate thin, it cannot be thinned while preventing the occurrence of casting defects. .

  FIG. 1 shows a schematic view of a cylinder head. 1A is a plan view seen from the bottom of the cylinder head, that is, the combustion chamber side, and FIG. 1B is a cross-sectional view taken along line A-A ′ in FIG.

As shown in FIG. 1B, the cylinder head 100 generally has a substantially rectangular parallelepiped outer shape formed by a bottom portion 110 and an outer wall portion 120 that rises from the outer periphery of the bottom portion. A protruding portion 150 such as an intake port that protrudes obliquely upward from the outer wall portion 2 is formed.
Inside the cylinder head, a shelf 130 such as an upper deck bridged by the outer wall 2 is provided.
Note that the bottom surface of the bottom portion 110 serves as a gasket surface facing a cylinder block (not shown).

  The cylinder head 100 is manufactured by a low-pressure casting method, and the molten metal is supplied from the fan gate 12 connected to the lower part of the cavity, and filled toward the upper side of the cavity.

The molten metal supplied to the cavity first flows separately in the direction of the bottom 1 and the direction of the vertical wall 2 as indicated by the arrows in FIG. 1 (b), and the molten metal surface rises so that the molten metal passes through the vertical wall 2 and the like. The shelf 130 is filled with molten metal.
However, since the thinned cylinder head is formed with a narrow molten metal flow path, that is, a cavity, the hot water circulation performance is lowered. In particular, the filling path to the upper shelf portion 130 bypasses, for example, an intake port, an exhaust port, or the like, so that the filling distance from the connecting portion of the fan gate 12 is long and bent. Therefore, the upper shelf 130 is not filled with sufficient molten metal, and casting defects are likely to occur.

  The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide a cast product that can prevent the occurrence of casting defects even in a thin and complex shape, and An object of the present invention is to provide a low pressure casting apparatus for producing a cast product.

  As a result of intensive studies to achieve the above object, the present inventors have provided a vertical wall that directly connects the upper shelf part and the fan gate connection part, which are difficult to circulate in the hot water, thereby shortening the filling path. It has been found that not only can the roundness be improved and the occurrence of casting defects can be prevented, but the rigidity of the entire cast molded product can be improved by the vertical wall, and the thickness can be further reduced, and the present invention has been completed.

  That is, the cast product of the present invention comprises a bottom, an outer wall that rises from the outer periphery of the bottom, and a shelf that is bridged by the outer wall. The cast product has a plurality of design parts formed by a runner of a casting apparatus on the bottom surface of the bottom part, and further has a vertical wall that directly connects the design part and the shelf part. To do.

The low-pressure casting apparatus of the present invention is for producing the cast product. The low-pressure casting apparatus includes a pouring gate disposed at a lower side of the cavity of the mold and spaced from the cavity, and a fan gate for communicating the pouring gate with the cavity.
The fan gate is connected to the lower surface of the cavity and has an upward slope from the gate toward the cavity.
Moreover, the said cavity forms the vertical wall which directly connects the design part of the cast molded product formed with the said fan gate, and the said shelf part.

  According to the present invention, since the vertical wall that directly connects the upper shelf portion that is difficult to circulate and the fan gate connection portion to which the molten metal is supplied is provided, the filling path to the upper shelf portion is shortened. As a result, it is possible to provide a cast-molded product that can be made thinner and thinner, and can achieve both weight reduction and prevention of casting defects.

(A) is the top view which looked at the cylinder head from the combustion chamber side. (B) is a figure which shows an example of the internal shape of a cylinder head. It is a figure which shows an example of the position of the plan part provided in the cylinder head of this invention, and a vertical wall. It is the schematic which shows an example of the low pressure casting apparatus of this invention. It is a graph which shows an example of the pressurization of a molten metal, and the pressure reduction pattern of a cavity. It is the schematic which shows an example of a fan gate.

A cylinder head as a cast product according to an embodiment of the present invention will be described in detail. The cylinder head is the most basic part constituting the engine together with the cylinder block.
FIG. 2 shows a schematic view of the cast product of the present invention. 2A is a plan view seen from the bottom of the cylinder head, that is, the combustion chamber side of the cylinder head, and FIG. 2B is a cross-sectional view taken along line AA ′ in FIG. FIG. 2C is a cross-sectional view taken along the line BB ′.
In addition, the plan part 160 shown to Fig.2 (a) has shown the location connected, and the fan-shaped part is abbreviate | omitted.

  As shown in FIG. 2B, the cast product includes a bottom portion 110, an outer wall portion 120 rising from the outer periphery of the bottom portion 110, and a plurality of shelves bridged by the outer wall portion. The shelf is a portion that extends in a substantially horizontal direction, and includes, for example, an upper deck 131, an intake port wall 132, an exhaust port wall 133, a valve guide 134, and the like.

Then, on the bottom surface of the bottom portion 110, a plan portion 160 formed by a runner of a low-pressure casting apparatus and solidified by molten metal is integrally connected.
The bottom surface of the bottom portion 110 is a gasket surface facing the cylinder block, and the design portion 160 is removed to form the cylinder head 100.

Specifically, as shown in FIG. 2B, the bottom 110 has an intake port wall 132 that forms an intake port 210 continuously with the combustion chamber wall 111 that becomes the ceiling surface of the combustion chamber 200, and An exhaust port wall 133 that forms the exhaust port 220 and a plug wall 170 that forms the spark plug mounting hole 230 are provided.
Note that the intake port and the exhaust port may protrude from the outer wall portion to form a protruding portion 150.

  An upper deck 131 is provided above the intake port 210 and the exhaust port 220, and a valve guide part 134 provided with a valve for opening and closing the intake port 210 or the exhaust port 220 is provided above the upper deck. And has a plurality of shelves.

  A hollow water jacket 140 through which cooling water flows is formed around the combustion chamber wall 111, the intake port wall 132, and the exhaust port wall 133.

  As shown in FIG. 2C, the cylinder head according to the present invention includes a vertical wall 180 that directly connects the above-described plan portion 160, that is, a connecting portion of a fan gate and a shelf portion such as the upper deck 131. The vertical wall 180 shortens the filling path to the shelf and makes it straight, thereby improving the hot water supply and preventing the occurrence of casting defects and improving the rigidity of the entire cast molded product. Thus, further thinning is possible and the weight is reduced.

The plan portion 160 and the vertical wall 180 extending from the plan portion 160 are preferably provided in the upper portion between the combustion chamber walls 111 as shown in FIGS. 2 (a) and 2 (c).
By providing the vertical wall 180 in the water jacket 140, not only the hot water circulation property to the upper deck 131 is improved, but also the rigidity of the entire cylinder head is improved, and the flow of cooling water can be improved.

That is, the cylinder head 100 has a generally small projected area from above, and it is difficult to secure a gate space under the cavity. In addition, since it is necessary to remove the plan portion 160, there is a concern that if the fan gate 12 is connected in the vicinity of the combustion chamber 200, it may affect the compression or the like. Many.
Accordingly, the shelf such as the upper deck 131 that extends in the substantially horizontal direction at the upper part of the combustion chamber is separated from the fan gate 12 provided on the outer periphery of the bottom 110 and the filling path is bent. It is a difficult part.

In the present invention, by providing the vertical wall 180, it becomes possible to fill the molten metal without using the outer wall portion 120, and the hot water circulation property is improved.
Further, by using a fan-shaped fan gate that expands toward the cavity, which will be described later, a gate space is secured, and the thickness of the design portion 160 is reduced, so that the design portion 160 can be easily removed.

Next, the low pressure casting apparatus of the present invention will be described.
A low-pressure casting apparatus 1 shown in FIG. 3 has a well-known basic structure, and includes a table-like stationary platen 2, a holding furnace 3 disposed below the stationary platen 2, and a pair standing upright on the stationary platen 2. A movable platen 5 that is driven up and down along the column 4 is provided. The fixed platen 2 is provided with a lower die (fixed die) 6L of the mold 6, and the movable platen 5 is provided with an upper die (movable die) 6U of the mold 6. The mold 6 forms a cavity C, which is a casting molding space, between the upper mold 6U and the lower mold 6L.

  On the upper surface of the movable platen 5, a pair of guide posts 7, an ejector plate 8 guided up and down by the guide posts 7, and a cylinder 9 that drives the ejector plate 8 up and down are provided. The ejector plate 8 is provided with an appropriate number of ejector pins 10 that slidably penetrate the movable platen 5 and the upper die 6U.

  Although not shown in the drawing, the low-pressure casting apparatus 1 has a driving device for moving the movable plate 5 up and down, a heater for heating the molten metal accommodated in the holding furnace 3, and a gas for pressurizing the inside of the holding furnace 3 during casting. A supply device or the like is provided, and the inside of the holding furnace 3 is pressurized to supply the molten metal to the cavity C through stalk (not shown).

Furthermore, as a more preferred embodiment, the low-pressure casting apparatus 1 may include a decompression device V that sucks the gas in the cavity C of the mold 6 as indicated by a virtual line in FIG.
When the molten metal is filled, air in the cavity C is supplementarily sucked by the decompression means V, so that the molten metal can be improved and the quality of the cast product can be improved.

  When the pressure reducing means V is provided, the molten metal in the holding furnace is pressurized to a predetermined initial pressure (+ P1) as shown in FIG. Thereafter, the molten metal in the holding furnace is pressurized to the filling pressure (+ P2), and the inside of the cavity is depressurized (−P) to fill the cavity with the molten metal.

  The low-pressure casting apparatus of the present invention is for molding a cylinder head as a cast product based on a low-pressure casting method, specifically, for manufacturing a cylinder head of an automobile engine shown in FIG. Aluminum or aluminum alloy is used.

The cylinder head generally has a substantially rectangular parallelepiped shape and has a small horizontal spread, so that the gate space under the cavity is limited. Therefore, when providing a plurality of gates, the gates are often connected to the outer peripheral portion of the cylinder head.
However, since the internal structure of the cylinder head is complicated, the molten metal filling path is bent and the distance through which the molten metal flows becomes long, so that it is difficult for the molten metal to travel to a substantially horizontal shelf-like portion at the upper center of the cylinder head. Casting defects are likely to occur in the cylinder head.

In the low-pressure casting apparatus 1 of the present invention, the gate is spaced from the cavity C and disposed below the cavity C, and the fan gate 12 that communicates with the lower surface of the cavity C and the gate 11 is disposed.
As shown in FIG. 5, the fan gate 12 has a fan shape that expands toward the cavity in plan view, and can supply molten metal over a wide range, and the sectional area gradually decreases toward the cavity. Since the thickness of the portion is the same as the thickness of the cavity, turbulence is unlikely to occur in the molten metal flowing into the cavity.

  The fan gate 12 is preferably connected to the lower surface of the cavity and has an upward slope toward the cavity. Since the cylinder head is formed by flowing a large amount of molten metal not only in the horizontal direction but also in the vertical direction, the molten metal can easily flow upward by being supplied from the lower surface of the cavity with an upward inclination.

Specifically, the flow of the molten metal from the fan gate connected to the outer periphery of the cavity can be dispersed in the direction of the outer wall 120 and the direction of the bottom 110, thereby improving the amount of hot water around the cylinder head. Moreover, the hot water performance can be further improved by directing the fan gate connected to the central portion of the cavity toward the vertical wall 180.
Although the said inclination | tilt angle is based also on the shape of a cavity, etc., it is preferable that it is 35 degrees-55 degrees.

  The fan gate 12 can be formed of a heat insulating member such as a sand mold.

  Further, the cavity C of the mold of the low-pressure casting apparatus of the present invention has a vertical wall 180 that directly connects the connecting portion of the fan gate and the substantially horizontal shelf-like portion at the center upper portion of the cylinder head shown in FIG. To form. Therefore, the filling path to the shelf-like portion is shortened and linear.

Further, the cross-sectional area of the connecting portion of the fan gate can be made different between the fan gates.
The amount of molten metal supplied by the fan gate may vary depending on the internal shape of the cavity, and the occurrence of casting defects such as air entrainment can be prevented by reducing the difference in filling time.

As shown in FIG. 2A, the low-pressure casting apparatus of the present invention includes a fan gate connected to the inside from the outer periphery of the cavity, specifically, between the combustion chamber wall 111 and the combustion chamber wall 111 at the bottom. . By supplying the molten metal also from the center of the lower surface of the cavity, the length of the molten metal filling path can be shortened as a whole.
The cavity forms a vertical wall that directly connects the fan gate connection between the combustion chamber walls 111 and the shelf such as the upper deck 131. Therefore, the molten metal can easily go around a substantially horizontal shelf portion such as the upper deck 131 at the upper center of the cylinder head.

  Further, when the cylinder head has a protruding portion 150 such as an intake port protruding from the outer wall portion of a substantially rectangular parallelepiped, a fan gate is provided immediately below the protruding portion, and the fan gate is connected in a substantially vertical direction. Is preferred.

  Further, as shown in FIG. 5, the gate is a hollow section having a circular cross-section with the upper end closed, and the fan gate 12 is connected to the side near the upper end, and is connected to the fan gate 12. A trap space 11A is provided on the upper side (upper end) than the section.

Since the low-pressure casting apparatus includes a trap space 11A at the upper end of the gate 11, when filling the cavity C with the molten metal, the oxide film on the molten metal surface and the solidified shell of the previous shot are captured in the trap space 11A. Only molten metal without impurities can be fed into the fan gate 12.
Further, since the fan gate 12 is inclined upward toward the cavity C, it is possible to prevent air from being entrained in the molten metal passing therethrough and to supply the molten metal upward.

The operation of the low pressure casting apparatus 1 will be described.
As shown in FIG. 3, the low-pressure casting apparatus 1 having the above configuration sets the sand mold 13 and the core 50 in the mold 6 and then lifts the ejector pin 10 together with the ejector plate 8 and moves the movable platen. 5 is lowered and the upper mold 6U and the lower mold 6L of the mold 6 are closed.

  Next, the molten metal is filled into the cavity C by pressurizing the inside of the holding furnace 3. At this time, it is also effective to suck the air in the cavity C by operating the decompression means V.

  Then, after the molten metal in the cavity C is solidified, the low-pressure casting apparatus 1 raises the movable platen 5 and opens the mold 6. Thereafter, a casting receiver (not shown) is disposed between the upper die 6U and the lower die 6L, the ejector pin 10 is lowered together with the ejector plate 8 to remove the casting from the mold 6, and the core 50 and the plan portion 160 are removed. To do.

The configuration of the low-pressure casting apparatus of the present invention is not limited to the above embodiment, and details of the configuration can be changed as appropriate without departing from the gist of the present invention.
Moreover, the low-pressure casting apparatus of the present invention can form various types of castings having a thin wall and a complicated internal structure based on the low-pressure casting method.

DESCRIPTION OF SYMBOLS 1 Low pressure casting apparatus 2 Fixed platen 3 Holding furnace 4 Support column 5 Movable platen 6 Mold 7 Guide post 8 Ejector plate 9 Cylinder 10 Ejector pin 0
DESCRIPTION OF SYMBOLS 11 Gate 12 C Fan V C Cavity V Pressure reducing device 100 Cylinder head 110 Bottom part 111 Combustion chamber wall 120 Outer wall part 130 Shelf part 131 Upper deck 132 Inlet port wall 133 Exhaust port wall 134 Valve guide part
140 Water jacket 150 Protruding portion 160 Design portion 170 Plug wall 180 Vertical wall 200 Combustion chamber 210 Intake port 220 Exhaust port 230 Spark plug mounting hole

Claims (9)

A cast product comprising a bottom, an outer wall rising from the outer periphery of the bottom, and a shelf bridged on the outer wall,
On the lower surface of the bottom portion, there are a plurality of design parts formed by the runner of the casting apparatus,
A cast product having a vertical wall directly connecting the design part and the shelf part.   2. The cast product according to claim 1, wherein the cast part has the design part inside the outer periphery of the bottom part, and has a vertical wall that directly connects the design part and the shelf part.   The cast product according to claim 1, wherein the plan portion has a fan shape in which a cross-sectional area gradually decreases toward a lower surface of the bottom portion and expands to a lower surface side of the bottom portion in a plan view. The above-mentioned plan part has an upward slope toward the bottom surface of the bottom part,
The cast molded article according to any one of claims 1 to 3, wherein an inclination angle is 35 ° to 55 °.   The cast product according to any one of claims 1 to 4, wherein the cast product is a cylinder head. A low-pressure casting apparatus for forming a cast product including a bottom, an outer wall rising from an outer periphery of the bottom, and a shelf bridged on the outer wall;
A gate below the cavity of the mold, spaced from the cavity,
A fan gate for communicating the gate and the cavity,
The fan gate is connected to the lower surface of the cavity, and the shape of the fan gate is a fan shape in which a cross-sectional area gradually decreases toward the cavity and expands toward the cavity in a plan view;
The low-pressure casting apparatus, wherein the cavity forms a vertical wall that directly connects a design part of a cast product formed by the fan gate and the shelf part. Having a fan gate connected to the inside of the outer periphery of the cavity;
The low-pressure casting apparatus according to claim 6, wherein the cavity forms a vertical wall that directly connects the connecting portion of the fan gate and the shelf. The fan gate has an upward slope toward the cavity;
The low-pressure casting apparatus according to claim 6 or 7, wherein the inclination angle is 35 ° to 55 °.   The low-pressure casting apparatus according to any one of claims 6 to 8, further comprising a decompression device that sucks the inside of the cavity of the mold.

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