JPS6313782B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for forming a mold used for lost wax casting.

(Prior Art) In the lost wax casting method, a mold must be made by attaching a mold forming material to the surface of a lost model made of wax or expanded polystyrene. One method for making this mold is to immerse the vanishing model in slurry stored in a slurry tank, to make the slurry adhere to the outside surface of the vanishing model, and before the slurry dries, sprinkle with stucco grains, and then dry it. There is a way to repeat it multiple times. in this case,
Once the ceramic layer reaches the specified thickness, dry it thoroughly.
Elute the disappearing model.

Since the inner surface of the mold made in this way becomes the casting surface of the cast product, it is important that the slurry and stucco particles that adhere to the disappearing model are uniformly attached to the surface of the disappearing model.

However, in the conventional method, it is difficult to completely prevent small air bubbles from adhering to the surface of the vanishing model when the vanishing model is immersed in a slurry tank. As a result, defects such as pinholes occur on the inner surface of the mold due to the air bubbles, resulting in a problem that the quality of the cast product deteriorates.

In addition, in the conventional method of immersing a vanishing model in a slurry tank, if the vanishing model has an edge-shaped corner, the amount of slurry attached to the corner will be reduced, and the mold will also become thinner at the part corresponding to the corner. For this reason, it is necessary to increase the number of times the slurry and stucco particles are attached to the mold so that the part corresponding to this corner has the minimum necessary thickness, which inevitably lengthens the drying time and reduces production efficiency. There were also problems.

Furthermore, when making large-sized cast products, this conventional method requires a large slurry tank, and there is also the problem that it becomes difficult to immerse the disappearing model in this large slurry tank.

(Problems to be Solved by the Invention) The present invention has been made in view of the above circumstances, and the air bubbles adhering to the vanishing model cause defects such as pinholes on the inner surface of the mold, resulting in the failure of the cast product. There are problems such as poor quality, poor adhesion of slurry to the corners of disappearing models, which reduces production efficiency, and the need for large slurry tanks when manufacturing molds for large casting products. This solves the problems that immersion of the disappearing model becomes difficult.

(Means for Solving the Problem) In order to solve this problem, the present invention uses a method of electrostatically coating a mold forming material such as slurry or stucco particles onto a disappearing model.
That is, the present invention provides a mold forming method in which a disappearing model is made to adhere to a disappearing model with a mold forming material and then dried, and then the disappearing model disappears. The structure is such that the charged mold material is electrodeposited onto the vanishing model.

The vanishing model is preferably made of wax or expanded polystyrene, and its surface is preferably electrically conductive. For example, in the case of a wax model, you can mix water into the wax, or if the wax itself lacks conductivity, you can make the model by applying a mixture of water and surfactant to the model surface. Conductivity can be imparted to the surface. Further, when the slurry is electrodeposited, the slurry mist droplets can be charged using a sprayer that sprays the slurry.
When electrodepositing stucco particles, if the stucco particles are previously impregnated with a surfactant, the stucco particles can be electrodeposited better on the model surface.

(Example) The present invention will be described in detail below based on the drawings.

FIG. 1 is a conceptual diagram showing an apparatus for electrodepositing slurry, which is an embodiment of the present invention. In this figure, numeral 10 is a motor, 12 is a core rod rotated by this motor 10, and 14 is a wax model as a disappearing model formed on this core rod. This wax model 14 is preferably made of conductive wax. For example, montan wax mixed with water homogeneously and emulsified is preferable because water has conductivity. Note that if a surfactant or an emulsifier is mixed in when water is mixed in, the proportion of water mixed in can be increased and the conductivity can be further improved. In addition, in the case of a vanishing model with poor conductivity, such as a vanishing model using filler wax mixed with a non-conductive synthetic resin or a vanishing model using foamed polystyrene, the surface of the vanishing model is coated with water and surfactant. It is preferable to apply the mixed solution by spraying or to immerse the disappearing model in this mixed solution because this mixture has conductivity. It is desirable that the core rod 12 be deeply inserted into the wax model 14. This is because the core rod 12 serves as an electrode.

16 is a sprayer, which includes a substantially cup-shaped rotating plate 18;
A motor 20 and a rotating plate 1 that controls the rotation of the motor 20.
8. The rotating plate 18 and rotating shaft 22 are made of metal, and this sprayer 16
It also serves as a means to charge the slurry.

24 is a DC power supply that applies high voltage between the wax model 14 and the sprayer 16. That is, the power source 24 maintains the wax model 14 at a positive level via the core rod 12 and the rotating plate 18 at a negative level via the rotating shaft 22.

26 is a sealable slurry tank in which slurry 28 is accommodated. 30 is a stirring propeller, and 32 is a motor that rotates this propeller 30. Pressurized air is supplied into the slurry tank 26 by an air pump (not shown), and the slurry 28 is sent onto the rotary plate 18 of the atomizer 16 by the air pressure.

In this embodiment, when the slurry 28 is dripped onto the rotating plate 18 from the slurry tank 26, the rotating plate 18
8, the slurry 28 is scattered in the form of mist in the outer circumferential direction. The mist droplets of this slurry 28 are transferred to the rotating plate 18.
is negatively charged by These charged slurry mist droplets are attracted to and adhere to the surface of the wax model 14 kept at a positive potential. The wax model 14 is rotated by the motor 10 and moved up and down, so that the slurry is evenly applied to the outer surface.

The wax model 14 to which the slurry has been applied is sprinkled with stucco particles and dried.

With the above, the first slurry and stucco grain adhesion process is completed. From the second time onwards, this first
The same process as the first time may be repeated, or it may be immersed in a slurry tank and then sprinkled with stucco grains as in the conventional method.

If the first slurry is applied by electrostatic coating in this way, the slurry 2 in the slurry tank 26 will be
Even if air bubbles are mixed in the slurry 28, the slurry 28 can be adhered to the surface of the wax model 14 without being affected by the air bubbles.
Therefore, defects such as pinholes caused by air bubbles do not occur on the inner surface of the mold.

Furthermore, as shown in the cross-sectional view of the wax model 14A in FIG.
If there is, the electric field density at this corner A will be higher, so more slurry 2 will be applied to this corner A than other parts.
8 is attached. In FIG. 2, the state of adhesion of the slurry 28 is exaggerated. As a result, many stucco particles adhere to the corner A, so that the number of repetitions of the slurry and stucco particle adhesion process can be reduced compared to the conventional method. That is, in the conventional method, the adhesion of the slurry and stucco particles at the corners is poor, so it is necessary to repeat the process of adhering the slurry and stucco particles so that the parts corresponding to the corners are sufficiently thick, which increases the number of repetitions. This not only increases the number of man-hours but also increases the drying time, significantly reducing production efficiency. However, according to the present invention, this problem is eliminated and production efficiency can be significantly increased.

Furthermore, when making large cast products, there is no need to use a large slurry tank to hold the disappearing model, and the slurry can be applied by moving the slurry sprayer 16, improving work efficiency. .

Note that the method of the present invention can be applied not only to the application of slurry but also to the application of other mold forming materials such as stucco particles. In particular, in the case of stucco particles, impregnating them with a surfactant improves the charging property and also improves the adhesion of the stucco particles.

Of course, the method of the present invention can be applied not only to the ceramic shell molding method that does not use sand backup, but also to the solid molding method that uses sand backup.

(Example) A wax model made of filler wax is immersed in a mixture of water and surfactant, and the
Position them 600mm apart. The wax model is about the size of a golf head. Other conditions are as follows.

Slurry viscosity 20sec (according to Zahn cut No. 4) Slurry supply rate 120c.c./min Rotating plate diameter 80mm Rotating plate rotation speed 2500r.pm Power supply voltage 90kV Working environment temperature 23℃ Under these conditions, slurry mist droplet diameter is 30μm
The slurry was applied to the surface of the wax model in a thickness of about 200 μm in several tens of seconds without containing any air bubbles. Even if the conductivity of the wax model was poor at the initial stage of coating, once even a small amount of slurry was applied, the conductivity improved and subsequent coating was promoted.

(Effects of the Invention) As described above, in the present invention, since the mold forming material is electrostatically coated on the surface of the disappearing model, air bubbles are prevented from forming in the mold forming material such as slurry or stucco particles applied to the disappearing model. No contamination occurs, and defects such as pinholes do not occur on the inner surface of the mold. This improves the quality of cast products. Further, more mold forming material adheres to the edge-like corners of the vanishing model than to other parts, and the mold becomes thicker at these corners than at other parts. Therefore, compared to conventional methods, the number of repetitions of applying the mold forming material can be reduced, reducing the number of steps. Therefore, drying time can be significantly shortened and production efficiency can be significantly improved. Furthermore, when creating a mold for a large casting product, there is no need to prepare a large slurry tank, and it is possible to fix a large vanishing model and apply it while moving the means for charging the mold forming material. It also has the effect of making it easier to create large molds.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of an embodiment of the present invention, and FIG. 2 is a sectional view of a wax model showing the state of slurry application. 14...Wax model as a disappearing model, 16...
Sprayer as means for charging, 24...power supply, 28
…slurry.

Claims (1)

[Scope of Claims] 1. A mold making method in which the disappearing model is made to disappear after attaching a mold forming material to the disappearing model and drying, the method comprising applying a DC voltage between the means for charging the mold forming material and the disappearing model. A mold forming method characterized by electrodepositing a charged mold forming material onto a vanishing model in a state where the mold forming material is electrically charged. 2. The mold making method according to claim 1, wherein at least the first deposition of the mold making material is carried out by electrodeposition, and the other appropriate depositions are carried out by immersing the mold making material in a tank containing the mold making material. . 3. The mold making method according to claim 1 or 2, wherein the disappearing model is made of wax, and water is uniformly mixed in the wax. 4 The vanishing model is made of wax, and filler wax containing synthetic resin as a main component is used for this wax, and a mixture of water and a surfactant is applied in advance to the vanishing model before electrodeposition of the molding material. A mold making method according to claim 1 or 2. 5. The mold making method according to claim 1 or 2, wherein the disappearing model is made of expanded polystyrene. 6. The mold making method according to claim 1 or 2, wherein the mold making material is a slurry, and the means is to charge a sprayer that sprays the slurry in the form of droplets. 7. The mold making method according to claim 1 or 2, wherein the mold making material is made of stucco particles, and the stucco particles are impregnated with a surfactant and charged. 8. Claim 1 or 2, wherein the mold is relatively thick for use in a ceramic shell molding method that does not use sand backup.
Mold manufacturing method described in section. 9 The mold is a solid mold using a sand backup.
The mold making method according to claim 1 or 2, wherein the mold is formed to be relatively thin so as to be used in a molding method.