JP3569243B2 - Sand mold for casting - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a casting sand mold used for manufacturing a metal casting such as an aluminum casting.
[0002]
[Prior art and its problems]
In sand mold casting, a wooden mold in the form of a product has been manufactured from the past, a mold in which the wooden mold is placed is filled with mold sand and hardened, and the sand mold obtained by removing the wooden mold is used as a mold, and the inside thereof is used as a mold. In this method, a molten metal is poured into a mold, and after cooling and solidifying, a sand mold is decomposed to take out a casting. In the casting method, a gravity method in which molten metal is injected into the mold from a gate on the upper surface of the mold, and a mold placed on a holding furnace having a pouring port opened upward, and a pressure is applied in the holding furnace. There is a low pressure method in which the molten metal inside is poured from the pouring port to the inside of the mold through the sprue on the lower surface of the mold, but in any case, volume shrinkage accompanying cooling and solidification of the molten metal inside the mold occurs. A feeder is generally provided on the upper surface side of the mold to compensate for the contraction volume. Further, in the mold applied to the gravity method, since the gate is opened upward, the gate is often used also as the feeder.
[0003]
For example, the sand mold shown in FIG. 6 is used for casting the aluminum alloy air surge tank T for an automobile engine shown in FIG. 5 by the gravity method, and the upper mold 11 and the lower mold 12 and the air surge tank T are used. And a core 13 which constitutes the internal space. The gates 11a and 11b provided in the upper mold 11 are also used as a feeder, and are vertically longer and inlet-side in order to secure a molten metal volume as a feeder and obtain a feeder pressure by potential energy. The diameter is set to be increased toward the upper side. 14 is an air vent hole provided in the upper mold 11, and 20 is a poured aluminum alloy. Although not shown, the upper die 11 is provided with a feeder corresponding to the tank component 21 of the air surge tank T separately from the gates 11a and 11b. The hot water also has a form that is expanded upward.
[0004]
[Problems to be solved by the invention]
As described above, in the conventional casting sand mold, the upper and lower thicknesses of the upper mold are increased in order to set the gate and the feeder which also serve as the feeder vertically longer, so that the weight of the upper mold and thus the entire mold is increased. There is a problem that a large amount of labor and energy are required for handling, and the amount of molding sand used for molding is increased.
[0005]
In order to reduce the weight of the mold, it is not impossible to make the gate and riser portions convex and reduce the thickness of the other areas in the vertical direction, but in this case the lid side of the mold to be filled with mold sand Needs to be formed into a special shape with irregularities, and the processing requires time and labor, and the cost of mold production is rather high. Also, in the conventional mold production, it is usual to form the mold for filling the mold sand into a simple box shape from the viewpoint of processing cost, so that the plane outer shape of the mold is rectangular regardless of the shape of the casting object. As a result, unnecessary weight is added to the mold due to unnecessary portions in terms of casting function such as strength, and the mold sand is wasted.
[0006]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a casting sand mold that can be easily reduced in weight and size, and can be manufactured efficiently at low cost.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a sand mold for casting according to the first aspect of the present invention has a three-dimensional sand mold member 1 provided with gates 4A and 4B opened upward, as indicated by reference numerals in the drawings. Each of the layers P _{1 to} Pn when the model is sliced in parallel into a plurality of layers is formed of a layered product M in which layers are sequentially formed as a bond-hardened layer by irradiating a laser beam L to the mold sand S layer, and the upper layer is opened above The upper portions of the spouts 4A, 4B are formed into a vertical cylinder and are integrally formed so as to protrude upward from the upper surface 10a of the main body portion 10 of the sand mold member 1 , and the inner space of the spouts 4A, 4B is expanded upward as a feeder. The outer diameter of the top portion of the vertical cylinder 40 is set to be larger than the outer diameter of the base portion, and the sand mold member 1 has a non-rectangular planar outer shape by removing a surplus portion corresponding to the shape of the casting object. It shall be.
[0008]
In the casting sand mold having the above-described configuration, the upper portions of the gates 4A and 4B protrude above the upper surface 10a of the main body 10 of the sand mold member 1. Therefore , the sand mold member is different from the conventional configuration in which the gate is opened on the upper surface of the sand mold member. In 1, the vertical thickness of the main body 10 is reduced by the amount of the protrusion, and the weight is reduced. Thus, in the case of a sand mold applied to the gravity type casting, particularly when the gates 4A and 4B are set to be vertically long so as to serve as a feeder, the weight of the main body 10 can be significantly reduced by the thinning of the main body 10 due to the protrusion. I can do it. The sand mold member 1 is obtained by a lamination molding method in which a thin layer of sand bound and hardened by the heat of a laser beam is laminated and integrated to obtain a three-dimensional molded article. as it is unnecessary to mold to fill the mold sand, even complex shape top sprue 4A, 4 B becomes protrude is very efficiently be manufactured. In addition, the vertical cylinder 40 also expands upward in accordance with the form in which the inner diameter of the sprues 4A and 4B expands upward, so that the entire vertical cylinder 40 has a substantially constant wall thickness as much as necessary. The sand mold member 1 can be further reduced in weight. The setting of the vertical cylinders 40 of the gates 4A and 4B in such a manner that the diameter thereof is increased upward is possible only by adopting the above-described additive manufacturing method which does not require die cutting. Further, the sand mold member 1 is unnecessary in terms of casting function such as strength and the like, and unnecessary portions are removed, so that the weight is reduced accordingly.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a sand mold for casting according to the present invention will be specifically described with reference to the drawings.
[0012]
The casting sand mold shown in FIG. 1 is used for casting the aluminum alloy air surge tank T for an automobile engine shown in FIG. 5 by the gravity method as described above, and includes an upper mold 1 and a lower mold 2. The air surge tank T is composed of a core 3 constituting an internal space. Each of the upper mold 1, the lower mold 2 and the core 3 is manufactured by a layered molding method using a mold sand as a molding material.
[0013]
The air surge tank T to be cast includes a horizontally long open tank component 21 which is connected to a manifold member with a branch pipe (not shown) to form a closed tank, and a J-shaped curved pipe communicating with the center of the tank 21. And a connecting flange 21a at the periphery of the opening of the tank 21 and a square flange 22a at the outer periphery of the distal end of the curved tube 22 for connection to the throttle port of the engine. Further, a reinforcing plate portion 23 connecting between the tank 21 and the curved tube portion 22 is provided.
[0014]
The core 3 has a substantially τ shape in which the tank space 3a and the curved tube space 3b are integrated, corresponding to the inner shape of the air surge tank T, and is a substantially rectangular baseboard extending over the entire width of the tank space 3a. 31 and a short-axis type baseboard 32 extending from the curved pipe space 3b.
[0015]
The upper die 1 is provided with two gates 4A and 4B which are open upward, a triple feeder 5 and an air vent hole 6. The upper portions of the gates 4A, 4B and the air vent hole 6 constitute vertical cylinders 40, 60 projecting upward from the upper surface 10a of the flat main body 10 of the upper die 1, and the triple feed gate 5 is provided. Also forms a horizontally long convex part 50 protruding upward from the upper surface 10a of the main body part 10.
[0016]
As shown in FIG. 4, the inner spaces of the gates 4A and 4B are set to be vertically long and have a diameter that is increased upward as a feeder. Correspondingly, each of the vertical cylinders 40 also has a shape whose diameter is increased upward, and the outer diameter of the top 40a is larger than the outer diameter of the base 40b, so that the entire vertical cylinder 40 has a substantially constant thickness. Have a thickness. Also, the convex portion 50 of the triple feeder 5 also has an outer width at the top that is larger than the outer width at the base, corresponding to the shape of the inner space that widens upward.
[0017]
On the upper surface side of the lower mold 2, a recess 7 that accommodates the lower half of the core 3 and forms a mold space, an arc-shaped recess 8 that forms a runner communicating with the gate 4 </ b> A, and an upper mold Truncated conical fitting projections 9a, 9a for positioning are formed. 7a and 7b in the recess 7 are baseboard receiving portions corresponding to the baseboards 31 and 32 of the core 3, and small recesses 8a and 8a connecting the recess 7 and the arc-shaped recess 8 are provided from the runner to the mold space. I'm coughing. As shown in FIGS. 4 and 5, the lower surface of the upper die 1 is opposed to the recess 7 of the lower die 2 so as to receive the upper half of the core 3 and form a die space. And a fitting recess 9b that fits properly with each fitting projection 9a. The spout 4B communicates with the runner facing the baseboard 32 of the core 3 on the upper mold 1 side, and the three feeders 5 are located at positions corresponding to the tank components 21 of the air surge tank T in the mold space. Is in communication with
[0018]
In addition, the planar outer shapes of the upper mold 1 and the lower mold 2 in the present embodiment are rectangular as shown by the imaginary line in FIG. 1 corresponding to the shape of the curved pipe portion 22 of the intake surge tank T as a casting. It is designed so as to form a non-rectangular shape by previously removing three extra regions Z away from the mold space.
[0019]
The upper mold 1 and lower mold 2 and the core 3 to be manufactured by a lamination molding method of above, when the parallel sliced into many layers P ₁ to PN having a thickness of about 150~250μm design models initially on Konpyuta The data of each cross-sectional pattern is created, and this data is input to the controller of the additive manufacturing apparatus, and the sliced layers are automatically converted by the modeling apparatus into the lowermost layer P by the molding material S (see FIGS. 2 and 3). _The layers are sequentially formed one by _one from one. The mold sand S generally includes a resin-coated sand in which the surface of sand particles is coated with a thermosetting resin component (for example, a mixture of a main resin such as a phenol resin and a hardening agent such as hexamethylenetetramine) as a binder. Used.
[0020]
2 and 3 are schematic longitudinal sectional side views showing an example of the additive manufacturing apparatus. In the additive manufacturing, as shown in FIG. 2, a base plate 43 is placed on an elevating table 42 arranged in a box-shaped modeling frame 41, and the horizontal movement of the recoater 44 cuts the mold sand S by the parallel slice. placed on base thick Supureto 43, it irradiates the laser beam L on the surface of this type sand S layer along section pattern of the bottom layer P _1. As a result, the thermosetting resin component on the particle surface of the mold sand S is melted by the heat of the laser beam L and undergoes a curing reaction, and adjacent sand particles are bound via the cured resin, and the entire irradiation area is integrally formed. first layer of a two-dimensional pattern consisting of a thin layer of the binder cured mold sand S will form a (lowermost layer) P _1. Then the elevating base 42 is lowered by the thickness of the one layer, newly loaded mold sand S in a thickness corresponding to one layer said similarly binder cured layer corresponding to the second layer P ₂ is irradiated with a laser beam L Then, in the same manner, the supply of the mold sand S and the irradiation of the laser beam L are repeated by sequentially lowering the elevating table 2 by one layer at a time, so that all the layers in the parallel slice are finally formed as shown in FIG. A laminated object M in which P _{1 to} P _n are laminated and integrated is formed. In FIG. 3, the upper mold 1 is shown as the layered product M.
[0021]
Thus, when the lamination molding is completed, the pace plate 43 is locked by the stopper 41a projecting inside the molding frame 41, the molding frame 41 is removed from the elevating table 42, and the uncured mold sand S is removed. Take out the layered product M. The recoater 44 receives the supply of the mold sand S from the material supply device 47 disposed at both ends of the movement stroke, and horizontally moves while flowing the mold sand S from the slit-like opening 44a at the lower end, so that the recoater 44 moves once. Is formed to form one mold sand S layer. 70 is a laser oscillator such as a carbon dioxide laser, and 71 is an XY scanner for controlling the irradiation direction of the laser beam L.
[0022]
In order to leave a certain amount of unreacted portion in the thermosetting resin component binding the sand particles, the obtained layered product M is usually subjected to a heat treatment for a predetermined period of time in a heating furnace or the like as post cure. Then, the resin component is completely cured.
[0023]
The upper and lower molds 1 and 2 and the core 3 of the laminate molded article thus obtained are assembled as shown in FIGS. 4 and 5 to form a mold, and the molten aluminum alloy 20 is poured into the mold space from the gates 4A and 4B. At the same time, the molten metal 20 is also supplied to the feeder port 5, and the molten metal 20 is cooled and hardened. The volume shrinks due to the cooling and hardening of the molten metal 20, but the shortage due to the shrinkage is replenished by the molten metal 20 filled in the gates 4A and 4B also serving as the riser and the riser 5 entering the mold space by its own weight. You. Thus, when the cooling and hardening of the molten metal 20 is completed, the mold is disassembled and the intake surge tank T of the casting is taken out. The core 3 can be easily removed from the hollow portion of the casting by vibrating and breaking it down into sand particles.
[0024]
In the casting sand mold having the above-described configuration, the gates 4A and 4B of the upper mold 1 are set to be vertically long so as to serve also as a feeder. Also, since the upper side of the feeder 5 is also formed by the convex portion 50, the gates 4A and 4B and the feeder 5 are opened on the upper surface of the main body 10, that is, the conventional structure shown in FIG. The vertical thickness of the main body 10 is much thinner than that of the upper die 11, and the vertical cylinder 40 and the convex portion 50 also correspond to the space form expanding above the gates 4A, 4B and the feeder gate 5 on the base side. The upper and lower dies 1 and 2 both have a non-rectangular planar outer shape excluding an extra region Z corresponding to the shape of the cast product.
[0025]
Accordingly, the casting sand mold is significantly lighter in weight than the conventional casting sand mold (see FIG. 6), and the labor and energy required for handling the casting sand mold are significantly reduced. The amount is small and can contribute to resource saving. Generally, it is said that a sand mold having a thickness of about 30 mm can sufficiently withstand casting.
[0026]
In addition, since this sand mold for casting is manufactured by a lamination molding method of obtaining a three-dimensional molded object by laminating and integrating a thin layer of sand that has been bound and hardened by the heat of a laser beam, a conventional method is used for the production. A mold for filling the mold sand and a wooden mold for the product are not required, and the spouts 4A and 4B and the feeder spout 5 can be manufactured extremely efficiently and in a short time even though they have a shape protruding from the main body 10. In addition, in the additive manufacturing method, since it is not necessary to remove the molded product, even if the vertical cylinders 40 of the gates 4A and 4B and the convex portion 50 of the feeder gate 5 are upwardly expanded, there is no problem at all. Can be manufactured.
[0027]
In the above embodiment, a casting sand mold used for casting an aluminum alloy air surge tank T for an automobile engine is exemplified. However, the present invention can be applied to all casting sand molds for obtaining castings of various forms. Needless to say, the present invention is also applicable to those without a core and those made of a sand mold member divided into three or more pieces. Although the sand mold of the above embodiment is used for gravity casting, the present invention can also be applied to a sand mold used for low pressure casting. The sand mold used in the latter casting method has a sprue opening on the lower surface. Therefore, in the present invention, a sand mold having an upwardly opening sprue is applicable.
[0028]
In addition, since the mold making is unnecessary in the additive manufacturing method as described above, a sand mold in which the core is integrated into the upper mold or the lower mold, or a non-divided mold, that is, an integral sand mold having a mold space inside is also manufactured. It is possible, and the present invention can be applied to these. Furthermore, according to the casting sand mold of the present invention, the number and arrangement of the gate and the feeder can be variously set according to the size and shape of the cast product, and the configuration in which the gate does not also serve as the feeder, and only the feeder and the feeder are used. A configuration without a feeder can also be employed.
[0029]
【The invention's effect】
According to the present invention, as casting sand mold, since the upper opening the hot water inlet upwardly protrudes upward from the body portion upper surface of the sand mold member, prior 該湯port is opened to the upper surface of the sand mold member construction It is much lighter than, especially when the length of a sand mold used for gravity casting is set up and down for dual use as a feeder, etc. In addition, energy is significantly reduced, the amount of mold sand used for mold production is reduced, which contributes to resource saving, and a product that can be produced efficiently at low cost is provided. In this casting sand mold, the upper part of the gate opening upward forms a vertical cylinder, and the outer diameter of the top of the vertical cylinder is set to be larger than the outer diameter of the base. The thickness of the sand mold member can be further reduced by making the thickness substantially constant at the limit. Moreover, since the planar outer shape of the sand mold member is non-rectangular except for the surplus portion corresponding to the shape of the casting object, the sand mold member is further reduced in weight.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a sand mold for casting according to one embodiment of the present invention.
FIG. 2 is a schematic vertical sectional side view showing an initial stage of manufacturing the sand mold for casting by an additive manufacturing method.
FIG. 3 is a schematic vertical sectional side view showing a final stage of production by the additive manufacturing method.
FIG. 4 is a longitudinal sectional view at a gate position showing a casting state by the casting sand mold.
FIG. 5 is a vertical sectional view at the position of the feeder, showing the same casting state.
FIG. 6 is a perspective view of an intake surge tank which is a casting using the same casting sand mold.
FIG. 7 is a longitudinal sectional view showing a casting state using a conventional sand mold for casting.
[Explanation of symbols]
1 upper mold (sand mold member)
DESCRIPTION OF SYMBOLS 10 Main body part 10a Upper surface 2 Lower mold 3 Core 4A, 4B Gate 40 Vertical cylinder 40a Top 40b Base ₅ Feeder 50 Convex part 6 Air vent hole 60 Vertical cylinder M Layered object L Laser beam P1-Pn Parallel sliced layer S type sand

Claims (1)

Sand mold member comprising a hot water outlet which is open upwardly, the layers at the time of parallel slices the three-dimensional model in multiple layers, the laminate shaped article according sequentially laminated as the binder cured layer by irradiation with a laser beam to the type sand made, it is integrally formed on the protruded upper part of the hot water port opening upward of the can form a vertical tube upwardly from the body portion upper surface of the sand mold member,
The inner space of this gate is expanded upward as a feeder, and the outer diameter of the top of the vertical cylinder is set to be larger than the outer diameter of the base,
A sand mold for casting, wherein the sand mold member has a non-rectangular planar outer shape by removing a surplus portion corresponding to the shape of the casting object .

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