JPH04367351A - Casting apparatus - Google Patents

Abstract

PURPOSE:To provide a casting apparatus, by which the casting having little deformation and high dimensional accuracy can be efficiently manufactured. CONSTITUTION:This casting apparatus fills filling material 2, such as molding sand, into a molding flask 1 connected operationally with an exciting device 6 and on the other hand, embeds a pattern 3 having the prescribed shape, gasifiable with heat, etc., of molten metal, in the above filling material 2 and four molten metal into the above pattern 3 and solidifies this to manufacture the casting having the prescribed shape. In this casting apparatus, an auxiliary exciting device 8 applying the vibration to the filling material 2 at the optional position, is set at the position facing to the above exciting device 6.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting apparatus, and more particularly to a casting apparatus capable of efficiently manufacturing a cast article with little deformation and high dimensional accuracy.

0002

2. Description of the Related Art Casting apparatuses are widely used in which a casting model that disappears due to the heat of the molten metal is replaced with molten metal, and then the replaced molten metal is solidified to produce a cast product of a predetermined shape.

[0003] Conventionally, an apparatus as shown in FIG. 6, for example, has been used as a casting apparatus using the above-mentioned disappearing casting model. That is, in this casting apparatus, a casting flask 1 is filled with a filler 2 such as molding sand, and a casting model 3 made of a material that disappears due to the heat of the molten metal, such as expanded polystyrene, is used as the filler 2. It is constructed by being buried inside. Further, the casting model 3 is equipped with a sprue 4 and a runner 5 for injecting molten metal, and vibration is applied to the casting frame 1 and filling 2 to fix the buried casting model 3 in a predetermined position. A device 6 is equipped to support the entire casting flask 1.

During casting, after a predetermined amount of filler 2 is filled into the casting flask 1, the investment casting model 3 is set, and the casting model 3 is further filled with the filler supplied from a filler supply device (not shown). After the filler is filled so as to bury the molten metal, the investment casting model 3 is fixed at a predetermined position in the casting flask 1 by applying vibration with the vibrating device 6, and molten metal is injected from the sprue 4. The molten metal reaches the investment casting model 3 through the runner 5, gasifies and disappears the model 3, and solidifies the molten metal replacing the investment casting model 3, thereby performing casting.

[0005]

[Problems to be Solved by the Invention] However, when casting is performed using the above-mentioned conventional casting equipment, the deformation of the cast product becomes noticeable, and a large number of man-hours are required to correct the product after casting. There was a problem in that the product yield was reduced and the economic efficiency was greatly impaired. Particularly in the case of cylindrical, thin-walled cast products such as case castings for electric motors, the above-mentioned tendency for deformation is even more pronounced, and in any case, drastic improvements have been desired.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a casting apparatus that can efficiently produce cast products with little deformation.

[0007]

Means and Effects for Solving the Problems The present inventors have repeatedly conducted various experiments in order to elucidate the causes of problems in conventional devices.

As a result, the inventors discovered that the cause of defective products in conventional devices lies in the vibrating method and vibrating device of the device. That is, according to the conventional apparatus, when the casting flask is vibrated, the vibrations are transmitted from the bottom and side surfaces of the casting flask, so that the packing density of the filler filled in the casting flask varies depending on the location. In other words, the closer to the vibrating device disposed on the bottom surface, the higher the packing density is, and the farther away from the vibrating device, the lower the packing density is. For this reason, the deformation force that the investment casting model itself receives varies depending on the distance from the vibration source (the vibration source) and the casting frame wall (the vibration medium).
As a result, we discovered a causal relationship in which the deformation of the casting becomes significant.

In order to clarify the problems with conventional devices, the present inventors attached minute pressure sensors to the surfaces of investment casting models having various shapes and investigated in detail the pressure distribution that acts on the casting models during filling. did.

That is, as shown in FIG. 7, a thin plate-shaped casting model 3a is embedded in the filling 2, and a plurality of pressure sensors are installed at predetermined intervals in the height direction on the front surface S1 and the back surface S2 of the casting model 3a. In the casting device equipped with 7,
The distribution of pressure acting on the casting model 3a when the vibration device 6 was driven was as shown in FIG.

On the other hand, as shown in FIG. 9, the pressure distribution of the filling material 2 can also be measured in a casting apparatus in which pressure sensors 7 are similarly installed in the height direction of the inner circumferential surface Sin and outer circumferential surface Sout of the thin-walled cylindrical casting model 3b. The measurement was performed and the results shown in FIG. 10 were obtained.

In the graphs shown in FIGS. 8 and 10,
The vertical axis is the pressure, and the horizontal axis is the distance from the vibration device 6. The white circle in the figure is the surface S of the thin plate-like investment casting model 3a.
1 and the outer peripheral surface Sou of the thin cylindrical investment casting model 3b
t , and the black circles are the pressure measurements on the back surface S2 of the thin plate-shaped investment casting model 3a and the inner circumferential surface Sin of the thin cylindrical investment casting model 3b.

As is clear from the results shown in FIGS. 8 and 10, it can be seen that in both cases, as the distance from the vibration device 6 increases, the pressure decreases. However, as shown in FIG. 8, the thin plate-shaped investment casting model 3a shows similar pressure values on both the front surface S1 and the back surface S2, and exhibits the same decreasing tendency, whereas the thin cylindrical investment casting model 3a 3b, the inner circumferential surface Sin and the outer circumferential surface Sout are significantly different, and the outer circumferential surface Sout
It was confirmed that the pressure difference at the inner peripheral surface Sin becomes larger as the distance from the vibration device 6 increases. Particularly in a casting apparatus using a thin cylindrical casting model 3b as shown in FIG. 9, the greater the pressure difference, the greater the amount of deformation of the investment casting model 3b during filling. As a result of investigating the degree of deformation of the casting after casting, it was found that the amount of deformation increases as the distance from the vibration device 6 increases, similar to the pressure difference. This is casting frame 1
Vibrations from the sides are blocked by the investment casting model 3b,
The present inventors have confirmed that this is due to the fact that the packing density of the filler 2 on the inner circumferential surface of the cylinder cannot be increased, and as a result, the filler cannot be uniformly arranged around the entire circumference of the casting model 3b.

In order to solve the above problem, the inventors attempted experiments by changing the excitation force of the vibration device 6, the shape of the casting flask 1, etc., but this problem could not be solved within the scope of the configuration of the conventional device. It was impossible to resolve.

[0015] However, as a result of further experiments, the inventors of the present invention discovered that when an auxiliary vibration device was installed to apply vibrations to arbitrary positions of the filling, in addition to the conventional vibration device,
We obtained the knowledge that the deformation force applied to the investment casting model can be minimized and that castings with less deformation can be manufactured. The present invention was completed based on the above findings.

That is, the casting apparatus according to the present invention fills a casting flask operatively connected to a vibrating device with a filler such as molding sand, while casting a casting model of a predetermined shape that disappears due to the heat of the molten metal. An auxiliary vibration device that is embedded in the filling and applies vibration to the filling at an arbitrary position in a casting device for manufacturing a cast product of a predetermined shape by pouring and solidifying molten metal into the casting model, It is characterized in that it is disposed at a position facing the vibration excitation device.

[0017] Furthermore, it is preferable that the auxiliary vibration device is configured to be movable with respect to the casting model.

When producing a casting using the above-mentioned casting apparatus, first a predetermined amount of filler is filled into the casting flask, and then
Set up an investment casting model that connects the sprue and runner. After that, the filling material is further filled into the casting flask by the filling material supply device (not shown) and the casting model is buried, and then the vibration device and the auxiliary vibration device are activated to vibrate the filling material and cast it. The filling density around the model is made uniform and the investment casting model is fixed in a predetermined position. After the investment casting model is fixed, molten metal is injected through the sprue. The molten metal reaches the investment casting model through the runner, gasifies the model and replaces it with the investment casting model, and then solidifies to obtain a cast product of a predetermined shape.

According to the casting apparatus having the above configuration, in addition to the conventional vibration device, an auxiliary vibration device is further provided at an opposing position, and this auxiliary vibration device can control the filling at any position. By applying vibration to the object, it is possible to make the packing density of the filling material more uniform around the entire circumference of the casting model. In particular, since the pressure difference between the outer circumferential surface and the inner circumferential surface of a cylindrical casting model is effectively reduced, a cast product with less deformation can be manufactured.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a sectional view showing an embodiment of a casting apparatus according to the present invention. Note that the same components as those of the conventional device shown in FIG. 6 are given the same reference numerals.

That is, in the casting apparatus according to this embodiment, a casting flask 1 operatively connected to a vibration device 6 is filled with a filler 2 such as molding sand, and a filler 2 of a predetermined shape that disappears due to the heat of the molten metal, etc. A casting model 3 is embedded in the filling material 2, and in a casting device for producing a cast product of a predetermined shape by casting and solidifying molten metal into the casting model material 3, vibration is applied to the filling material 2 located at an arbitrary position. An auxiliary vibration device 8 for applying vibration is disposed at a position facing the vibration device 6.

The casting model 3 is made of foamed polystyrene or the like, and is embedded in the filling 2 after a sprue 4 and a runner 5 for passing the molten metal are attached in advance.

The auxiliary vibration device 8 is mounted on a base 9 that moves in the horizontal direction, and this base 9 is integrally connected to a lifting mechanism 10 that moves in the vertical direction. Therefore, the tip vibrating part 8a of the auxiliary vibrating device 8 is configured to be movable with respect to the casting model 3, and is configured to be able to apply vibration to the filling material 2 located at an arbitrary position within the casting flask 1. . Note that the auxiliary vibration excitation device is not connected to other vibration sources (as shown in Figure 1).
(not shown), or may be integrally fixed to the side wall of the casting flask 1.

Furthermore, depending on the shape of the cast product to be manufactured, the packing density of the filler to be filled around and inside the casting model differs, and the time required to make the packing density uniform also differs, so the above-mentioned processing is necessary. It is desirable that the vibration force, vibration start time, vibration end time, etc. of the vibration device 6 and the auxiliary vibration device 8 can be set individually.

In order to confirm the effect of the casting apparatus according to this embodiment equipped with the auxiliary vibration device 8, FIGS.
The pressure distribution of the filler acting on the inner and outer peripheral surfaces of the cast model was measured in the same manner as the experiment shown in .

That is, as a casting model, an investment casting model 3c for forming a motor case casting as shown in FIG. 2 was prepared. This casting model 3c is molded from thin cylindrical foamed polystyrene. After arranging a plurality of pressure sensors 7 at predetermined intervals in the height direction of the inner circumferential surface Sin and outer circumferential surface Sout of this casting model 3c, they are embedded in the filling material 2 of the casting apparatus shown in FIG. After operating the vibrating device 6 and the auxiliary vibrating device 8 for a predetermined time with the vibrating part 8a of the device 8 disposed at the axial center of the casting model 3c, the pressure values are read from each pressure sensor 7 and are shown in FIG. I got similar results.

In the graph shown in FIG. 4, the vertical axis represents pressure and the horizontal axis represents distance from the vibration device 6. The open circles in the figure represent the pressure at the outer peripheral surface Sout of the thin plate cylindrical investment casting model 3c, and the black circles represent the pressure at the inner peripheral surface Sin. Although it is recognized that the pressure tends to decrease as the distance from the vibration device 6 increases, the decrease in pressure is slight compared to the results shown in FIG. 10 obtained without using the auxiliary vibration device 8. Furthermore, it can be seen that the pressure difference between the outer circumferential surface Sout and the inner circumferential surface Sin is almost eliminated.

Next, the procedure for performing casting using the investment casting model 3c for forming a motor case casting shown in FIG. 2 will be described below.

As shown in the casting apparatus of FIG. 1, the casting model 3c is molded from expanded polystyrene, and a sprue 4 and a runner 5, which are also molded from expanded polystyrene, are attached to this investment casting model 3c. It is being On the outside of the investment casting model 3c, SiO2, Al2O
3. A coating layer mainly composed of mineral particles such as MgO is formed (not shown). By forming this coating layer, it is possible to effectively prevent the molten metal from entering the sand mold (filling material) and from collapsing the mold itself, and at the same time, it is possible to smooth the surface of the cast product.

First, a predetermined amount of silica sand as the filler 2 is filled into the casting flask 1, and the surface is made sufficiently flat. Then, the investment casting model 3c with the sprue 4 and the runner 5 attached is set, and further casting is carried out. Fill the model 3c with silica sand. After burying the investment casting model 3c, the elevating mechanism 10 and the base 9 are driven, and the auxiliary vibration device 8 is lowered so that the vibration part 8a of the auxiliary vibration device 8 is placed at the center of the inner diameter of the cylindrical investment casting model 3c. bury it. Thereafter, the vibrating device 6 and the auxiliary vibrating device 8 are operated to make the filling uniform, and to sufficiently fix the investment casting model 3c. Vibration device 8 at this time
The excitation force and excitation start time and end time of the auxiliary excitation device 8 may be set to optimal values depending on the shape of the product.

After the fixation of the investment casting model 3c is completed, molten metal is injected through the sprue 4. The molten metal reaches the investment casting model through the runner 5, and by gasifying and disappearing the casting model 3c, it is replaced with the investment casting model and casting is performed. Gas generated during casting is removed using a gas exhaust device (not shown). The casting is then completed through a cooling process.

According to the casting apparatus according to this embodiment, in addition to the conventional vibrating device 6, an auxiliary vibrating device 8 is further provided at an opposing position, and this auxiliary vibrating device 8 allows arbitrary By applying vibration to the filling material 2 in the position, it becomes possible to make the packing density of the filling material 2 more uniform around the entire circumference of the casting model 3c. In particular, it is possible to minimize the difference in packing density of the filling material in the casting flask 1, and to minimize the difference in packing density between the outer circumferential surface Sout and the inner circumferential surface Sin of the cylindrical casting model 3c.
Since the pressure difference between
It is possible to produce high-quality cast products with little deformation.

In the above embodiment, one vibrating section 8a
Although a casting machine equipped with an auxiliary vibrator 8 having a It is also possible to use an auxiliary vibrating device having a vibrating section, which can be selected as appropriate.

The casting apparatus according to the present invention can also be used as a component of a continuous casting apparatus, as shown in FIG. 5 as an example.

[0035] This continuous casting apparatus has an arrangement of casting flasks 1,
The steps of filling the filler 2, arranging the casting model 3c, embedding the casting model 3c, making the filling density uniform by vibration, and pouring (pouring) are performed continuously at each station.

A large number of prepared casting flasks 1 are placed on a hydraulically driven conveyance device 11 and are intermittently moved to the subsequent process. The casting flask 1 filled with a predetermined amount of filler 2 via the filler supply device 12 at station 1 is moved to station 2 by the conveyor device 11, where the surface of the filled layer is made sufficiently flat. Afterwards, the investment casting model 3c with the sprue 4 and runner 5 attached is placed on the flattened surface. Furthermore, in the suite 3, the filling 2
The filling 2 is filled into the casting flask 1 from the filling supply device 12 until the filling height reaches the upper end of the sprue 4.

Next, at the station 4, the elevating mechanism 10 and the like are driven to bury the auxiliary vibration device 8 in a predetermined position. The optimal burial position differs depending on the shape of the casting model, etc., but the optimal burial position differs depending on the shape of the casting model, etc.
When using the auxiliary vibrating device 8, it is preferable to lower the auxiliary vibrating device 8 in the direction of the center axis of the cylindrical casting model 3c so that its vibrating part is buried in the filling material 2. In this state, the vibration device 6 disposed at the lower end of the casting flask 1 and the auxiliary vibration device 8 disposed at the center of the casting model 3c are driven for a predetermined period of time.

At this time, the vibrations applied by the vibrator 6 to the entire filling 2 from the bottom of the casting flask 1 and the casting model 3
The filling density of the filling material 2 in contact with the entire surface of the casting model 3c increases due to the vibration added by the auxiliary vibration device 8 to the filling material 2 filled in the center of the casting model 3c.
The pressure difference between the inner circumferential surface Sin and the outer circumferential surface Sout is reduced. Then, the filling density of the filling material 2 is made uniform, and the casting model 3c is fixed in a predetermined position. After a predetermined vibration time has elapsed, the auxiliary vibration device 8 is slowly raised upward while vibrating, and is pulled out above the filling 2.

Next, the casting flask 1 is transported to a station 5 where a pouring process is performed. At station 5, molten metal 14 stored in ladle 13 is injected from sprue 4. The injected molten metal 14 reaches the investment casting model 3c via the runner 5 buried in the filler 2, and the model 3c is gasified and disappeared, replacing it with the investment casting model, and casting is performed. Gas and dust generated during casting are exhausted to the outside of the system by a gas exhaust device 15 connected to an exhaust blower (not shown).

In this way, a casting frame 1 is placed at each station.
is fed intermittently, making continuous casting possible.

In addition, as a result of investigating the amount of deformation of the casting after casting, it was found that in the device of this embodiment using the auxiliary vibration device 8,
Compared to conventional equipment that does not use an auxiliary vibration device, the amount of deformation is significantly reduced, the number of man-hours required for secondary processing of cast products is significantly reduced, and the manufacturing yield of cast products is significantly improved. was completed.

As described above, in the casting apparatus according to this embodiment as well, the casting model 3c is
Compared to conventional equipment, it is possible to make the packing density of the filler filled on the inner and outer circumferential surfaces of the machine more uniform, resulting in less deformation and
High precision castings can be manufactured.

In other words, in the conventional device, a large number of man-hours were required to shape the cast product after casting, but with the device of this embodiment, even thin-walled cylindrical castings such as motor case castings can be easily deformed. , can carry out high quality casting operations.

Although the above embodiment shows an example of forming a thin-walled cylindrical cast product such as a motor case, the present invention is not limited thereto, and the vibration position of the auxiliary vibration device and the vibration By changing the force appropriately, the method can be similarly applied to manufacturing castings of any shape.

[0045]

[Effects of the Invention] As explained above, according to the casting apparatus according to the present invention, in addition to the conventional vibration excitation device, an auxiliary vibration device is further equipped at an opposing position. By applying vibration to the filler at an arbitrary position, it is possible to make the packing density of the filler more uniform around the entire circumference of the casting model. In particular, since the pressure difference between the outer circumferential surface and the inner circumferential surface of a cylindrical casting model is effectively reduced, a cast product with less deformation can be manufactured.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a casting apparatus according to the present invention.

FIG. 2 is a perspective view showing an investment casting model for casting the motor case casting produced in the example.

FIG. 3 is a sectional view of a casting apparatus according to an embodiment in which a thin cylindrical casting model is embedded.

FIG. 4 is a graph showing the distribution of pressure acting on the casting model shown in FIG. 3;

FIG. 5 is a perspective view showing the configuration of a continuous casting apparatus according to another embodiment of the present invention.

FIG. 6 is a sectional view showing a configuration example of a conventional casting device.

FIG. 7 is a sectional view of a conventional casting device in which a thin plate-shaped casting model is embedded.

8 is a graph showing the distribution of pressure acting on the casting model shown in FIG. 7. FIG.

FIG. 9 is a sectional view of a casting apparatus according to an embodiment in which a thin cylindrical casting model is embedded.

FIG. 10 is a graph showing the distribution of pressure acting on the casting model shown in FIG. 9;

[Explanation of symbols]

1 Casting frame 2 Filler (foundry sand) 3, 3a, 3b, 3c Casting model 4 Sprue 5 Hot water path 6 Vibration device 7 Pressure sensor 8 Auxiliary vibration device 8a Vibration part 9. Base 10 Lifting mechanism 11 Conveyance device 12 Filling supply device 13 Ladle 14 Molten metal 15 Gas exhaust device

Claims (2)

[Claims] Claim 1: A casting flask operatively connected to a vibration device is filled with a filler such as molding sand, and a casting model having a predetermined shape that disappears due to heat of the molten metal is buried in the filler. , in the casting device for manufacturing a cast product of a predetermined shape by pouring and solidifying molten metal into the casting model, an auxiliary vibration device for applying vibration to a filling material located at an arbitrary position is arranged opposite to the vibration device. A casting device characterized in that it is arranged at a position. 2. The casting apparatus according to claim 1, wherein the auxiliary vibration device is configured to be movable with respect to the casting model.