JP2004136325A - Method for assembling lost foam pattern, casting method with lost foam pattern and solid matter for combing lost foam pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new structure with which patterns used for a lost foam pattern casting method are easily and precisely assembled, and its method. <P>SOLUTION: In a method for obtaining the lost foam pattern assembling a plurality of separated constituting elements, respective constituting elements are combined by fitting solid matters possible to lose with molten metal into recessed parts arranged at the positions corresponding to the respective constituting elements for combining. Since the respective constituting elements are combined by fitting the solid matters into holes precisely opened and this state is held, slippage of the pattern is hardly developed. Therefore, defect in the obtained cast product can be reduced. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for assembling a disappearing model in casting using a disappearing model, the disappearing model, a casting method using the disappearing model, and a solid body for joining the disappearing model.
[0002]
[Prior art]
A casting method using a vanishing model (hereinafter, vanishing model casting method) is widely known. In general, the disappearing model casting method is to bury a disappearing model formed of expanded polystyrene or the like in a sand mold, inject molten metal, vaporize the lost model and eliminate it, and put molten metal in the resulting gap. This is a casting method to make a casting by filling.
[0003]
In order to manufacture a model used for this purpose, it has been conventional to assemble the parts constituting the model while joining them with an adhesive such as glue. However, when joining cannot be performed with high accuracy, a step or the like occurs on the mating surface, or when trying to join a thin and large object, if one end is joined correctly, the other end cannot be joined properly. There is a problem that it is difficult to assemble the vanishing model, and as the number of parts to be joined increases, the joining accuracy between the parts deteriorates.
[0004]
In addition, when a large amount of adhesive such as glue is applied, the accuracy is degraded by the thickness of the glue. In particular, when parts are stacked in several layers, a phenomenon that the accuracy of the model is further deteriorated was observed.
[0005]
In addition, since the vanishing model casting method is a method of producing a casting while replacing (disappearing) a model, a carbon material remains and becomes a defect in a model material in which the model is not easily decomposed by a molten metal. There was a problem. This defect is called a residue defect. For example, hard expanded polystyrene and the like having a low expansion ratio have a problem that carbon generated by carbonization of styrene remains in the casting as a residue.
[0006]
Also, the expanded polystyrene model is easily deformed due to its low strength, and when assembling after manufacturing each part, it is difficult to accurately join the parts with thin or large structures. For this reason, after applying the bonding agent to the components, the components are carefully combined, and after the overlapping, the components are adjusted from the surroundings using a tape or the like so that the components can be accurately bonded to each other. However, even in the case of a large-sized structure or the like, even if the work is carefully performed, a step is generated in a joint portion between the components, and the accuracy of the model often deteriorates. In addition, the dimensions were often out of order by the thickness of the glue.
[0007]
[Problems to be solved by the invention]
The present invention solves such a problem, and makes it possible to assemble a model reliably and accurately.
[0008]
That is, first, the present invention is a method of obtaining a disappearing model by assembling a plurality of separated components, and inserting a solid that can be removed by a molten metal into a concave portion provided at a corresponding position of each component to be combined. Then, the respective components are combined with each other. Since this solid is fitted into a hole that has been accurately drilled and combined with each other to maintain its state, the model is unlikely to be displaced. Therefore, the obtained casting can also reduce defects. In addition, even if an adhesive is used for more firm bonding, the amount of the adhesive can be reduced, and variations in accuracy caused by the thickness of the adhesive can be suppressed.
[0009]
Preferably, the solid is a wax, for example, comprising a wax-based material selected from the group of paraffin, paraffin wax, wood wax, microcrystalline wax, petrolatum, montan wax, and wax.
[0010]
By using a wax-based material having good slippage for the solid matter for binding, the solid matter for binding can be easily inserted into the concave portion provided in each component, and the solid matter for binding can be used between the components. Can be easily combined and assembled. In addition, since these substances have a low melting point and an excellent permeability into the mold after liquefaction, they are instantaneously discharged to the mold side, so that unnecessary residues are hardly generated, and products (castings) The yield was also improved.
[0011]
Preferably, the concave portion is formed by machining by a program, whereby the accuracy of the assembled model can be improved. Also, when assembling two or more concave parts, if the accuracy of the holes is not good, even when they are combined, distortion occurs, frictional resistance increases, and it may be difficult to combine them. Especially necessary.
[0012]
More preferably, the bonding surfaces of the components are bonded to each other. This makes it possible to more firmly connect the components and maintain the accuracy.
[0013]
After bonding, it is bonded while pressing in the elastic range of the compressive strength of the disappearing model material to prevent deformation while increasing the bonding, and excess adhesive is discharged outside the model to make it thinner. Prevention of dimensional deviation due to the thickness of the agent, and improved accuracy of the disappearing model.
[0014]
The present invention also provides a method of performing casting using a vanishing model obtained by combining a plurality of separated components. It is characterized in that a solid material that can be eliminated by a molten metal is fitted into a concave portion provided at a corresponding position of each component to be coupled, the respective components are coupled, and the molten metal is cast into the assembled disappearance model. Things.
[0015]
Preferably, the solid is a wax. The temperature of the molten metal is preferably 600 ° C. or higher.
[0016]
Furthermore, it is preferred that the solid is a wax and that the total volume ratio of the wax used to the volume of the melt is such that it does not substantially affect the casting. For example, the volume ratio is 15%.
[0017]
In addition, the bonding strength can be further increased by bonding the joining surfaces of the respective components and joining the respective components before casting the molten metal, and the components that have been accurately coupled can be easily formed. There is no shift.
[0018]
Furthermore, by bonding while applying pressure within the elastic range of the compressive strength of the vanishing model material, while preventing deformation of the vanishing model, the adhesive strength is further increased, and excess adhesive is discharged to the outside of the model to provide more adhesive. The thickness of the adhesive can be reduced, the deviation of the dimensions due to the thickness of the adhesive can be prevented, and the accuracy of the disappearing model can be improved.
[0019]
The present invention also provides a vanishing model assembled by combining a plurality of separated components, which can be vanished by molten metal in a concave portion provided at a corresponding position of each component to be coupled. It is characterized in that a solid is inserted.
[0020]
The recess is formed by machining by a program.
[0021]
An adhesive is applied to and joined to the joint surfaces of the components.
[0022]
The invention of the present application further provides a solid for binding to be provided in a vanishing model assembled by combining a plurality of separated components, the solid being capable of being vanished by a molten metal. It is characterized by being.
[0023]
Preferably, the solid is a wax, for example, consisting of a wax-based material selected from the group of paraffin, paraffin wax, wood wax, microcrystalline wax, petrolatum, montan wax, wax.
[0024]
Further, in order to facilitate the disappearance by the molten metal, the solid is a wax having a melting point of 35 to 150 ° C.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
The method for assembling the disappearing model, the casting method using the disappearing model, the disappearing model, and the solid for joining the disappearing model according to the present invention will be described with reference to embodiments. However, the present invention is not limited to these embodiments. .
[0026]
FIG. 1 shows an example of a vanishing model and a binding solid used in the vanishing model. The vanishing model 10 is formed by joining one model 1 and the other model 2, which are constituent elements thereof, so that their joint surfaces 1a and 2a are respectively aligned.
[0027]
The models 1 and 2 are both polystyrene foam in this example, but may be other materials that can be used in the vanishing model casting method.
[0028]
Holes 1b and 2b that become concave portions are provided at positions corresponding to each other when the models 1 and 2 are coupled to each other on the joining surfaces 1a and 2a of the models 1 and 2. One end is fitted into the hole 1b so that the other end of the solid 3 is protruded, and the other end of the solid 3 is fitted into the other hole 2b. The models 1 and 2 are combined so that the surfaces 1a and 2a are brought together to form a vanishing model.
[0029]
The solid 3 for bonding is vaporized and substantially disappears in the same manner as the models 1 and 2 during the casting of the molten metal for casting, and the space of the solid 3 for bonding can be filled with the molten metal. It is preferable that the bonding solids 3 do not remain in the casting product after pouring or react with the molten metal to generate unnecessary gas.
[0030]
The present inventor has confirmed many organic substances, such as solid polystyrene, which are the same as the model, as the solid substance 3 for bonding, but many of them remain as carbides in the product or react with the molten metal to generate gas. However, this resulted in gas defects in the product. By improving the conditions such as the manufacturing process and the temperature, it is conceivable that such a substance will not cause a problem, but at present, it has been found that a wax-based substance is convenient. Examples of the wax-based substance include paraffin, paraffin wax, wax, wood wax, microcrystalline wax, perolatam, montan wax, wax, and the like.
[0031]
It is considered that these substances have a low melting point and excellent permeability into the mold after liquefaction. A more detailed investigation has shown that wax does not cause problems in the melt due to the following reasons.
[0032]
First, in the case of a molten metal having a casting temperature of 600 ° C. or more, such as cast iron or cast steel or copper or aluminum, when the molten metal approaches the wax at this temperature, the wax having a melting point of 35 to 150 ° C. is instantaneously melted. Since the molten wax has good permeability, it is instantly discharged to the mold side. On the other hand, even a substance having a low melting point, which has poor permeability, adheres to the mold wall surface and causes a casting surface defect. Thus, waxes having a melting point of 35-150 ° C. have been found to be particularly effective. It has also been found that the use of wax as the binding solid 3 facilitates easy assembly into the holes 1b and 2b when the models 1 and 2 are combined.
[0033]
The holes 1b, 2b are formed inside the models 1, 2 so as to be dug vertically from the joint surfaces 1a, 2a to form a cylindrical cavity. In addition, the binding solid 3 has a shape adapted to fit inside the cavity formed by the holes 1b, 2b and fit into the holes 1b, 2b. The depth of each of the cavities of the holes 1b, 2b is smaller than the length of the binding solid 3 so that one end protrudes from the joining surfaces 1a, 2a even if the binding solid 3 is inserted into any of the holes 1b, 2b. The sum of the depths of 2b is at least greater than the length of the binding solid 3 so that the binding solid 3 fits within the cylindrical cavity formed by the holes 1b, 2b. The diameter of the binding solid 3 is at least partially such that the binding solid 3 is inserted into the holes 1b and 2b and the models 1 and 2 are not displaced from each other. It has the same diameter as 1b and 2b, or a rod having a slightly larger diameter such that accuracy does not substantially degrade when the model is deformable such as foamed polystyrene. Further, preferably, both ends or at least one end in the shape of a rod are tapered or hemispherical in order to make it easier to insert the binding solid 3 into the holes 1b, 2b.
[0034]
In this example, the diameter of the holes 1b and 2b was 10 mm, and the depth was 25 mm. As the wax used as the binding solid 3, a rod-shaped wax having a diameter of 10 mm and a length of 40 mm was used so as to correspond to the diameters of the holes 1b and 2b. However, the shapes of the holes 1b and 2b and the shape of the solid body 3 for connection corresponding thereto are not limited to this example as long as the models 1 and 2 can be mutually connected with high accuracy.
[0035]
The holes 1b and 2b were made by an NC machine that can be machined by a program. As a result, the displacement of the holes is eliminated, and the assembly can be performed with high accuracy.
[0036]
The number of the rod-shaped waxes 3 was 26 so that the total weight of the waxes 3 used was within 15% of the weight of the molten metal. This prevents unnecessary wax components from remaining in the finished casting.
[0037]
The method of assembling the disappearing model is as follows. First, the models 1 and 2 are prepared, and one end of the rod-shaped wax 3 is inserted into the hole 1b or 2b of the model 1 or 2. Thereafter, the model 1 and the model 2 are combined so that the other end of the wax 3 enters the hole 2b or 1b of the model 2 or 1. The insertion of the wax 3 may be entirely inserted into one of the models 1 as shown in FIG. 2A, or may be alternately or arbitrarily inserted into both models 1 and 2 as shown in FIG. 2B. In this example, at least one end of the wax 3 is hemispherical as shown in FIG. 2, so that the models 1 and 2 can be easily combined.
[0038]
The joining surfaces 1a and 2a of the combined models 1 and 2 whose positions are fixed by the wax 3 may be joined with an adhesive such as glue. In this case, before combining the model 1 and the model 2, an adhesive is applied in advance. In this example, the adhesive was applied after the solid body 3 for bonding was inserted into one of the models 1.
[0039]
After the models 1 and 2 were combined, the models 1 and 2 were joined while being pressed within the elastic range of the compressive strength of the material. As a result, excess glue is discharged to the outside of the model, uniform bonding can be performed, and dimensional deviation due to glue has been eliminated.
[0040]
In the case of expanded polystyrene foamed 50 times, the normal pressure is in the range of 3 to 150 g / cm ² . Further, when a high-strength material such as an iron plate and a low-strength material such as expanded polystyrene used in a vanishing model casting method are subjected to pressure, there is a problem that only the surface layer of the weak material is deformed. For this reason, as shown in FIG. 3, by applying pressure through the plate 5 of the same material as the material of the disappearing model, the problem of partial deformation could be avoided. Although the plate 5 is a flat plate in this example, if the outer shape of the disappearing model includes many irregularities, it may be made according to the outer shape. As a result, since the pressure can be applied in a wider range, the pressing force can be uniformly distributed and the pressing force can be dispersed throughout, so that excessive deformation of the disappearing model can be prevented.
[0041]
By using the disappearing model 10 in which the adhesive is solidified and integrated, a mold can be applied and molded in the same manner as a general disappearing model casting method. Here, a coating mold for a disappearing model was used. The mold used was a furan-based organic self-hardening mold that solidifies sand by the reaction of a furan resin and a curing agent.
[0042]
When the solid 3 for bonding was a solid wax having a melting point of 30 to 150 ° C., it was found that the casting temperature was preferably 600 ° C. or higher. Under these conditions, it was found that the wax did not remain inside, and the wax fluidized before reacting with the molten metal and was discharged out of the mold.
[0043]
In this example, low melting point wax 3 that melts at about 65 ° C. was used. The temperature of the molten metal at the time of pouring into the mold was set to 1,400 ° C. in order to allow at least 600 ° C. or more of the molten metal to flow into the model of the product even if the temperature of the molten metal was lowered by cooling to the mold. If pouring is performed at 1,400 ° C., when the molten metal enters, the wax 3 in the model starts to melt. The melted wax 3 is discharged to the mold side.
[0044]
If the melting temperature is 600 ° C. or lower, the melting of the wax 3 is delayed, so that the wax 3 may react with the molten metal before being completely discharged to the mold side, and may cause gas defects. Further, the molten wax has a high permeability to the mold, and is discharged to the mold side without adhering to the mold wall surface. Therefore, the wax 3 does not remain in the model (in the product) and has no adverse effect on the product.
[0045]
As described above, a concave portion was provided in each component constituting the vanishing model. Then, a new connecting solid that can be fitted into the recess is newly conceived, and the components are connected by the connecting solid to assemble the entire disappearance model. The solid material for binding was used as a material that disappeared by the molten metal in the same manner as the disappearance model. As a result, not only can the disappearing model be more easily assembled, but also a highly accurate disappearing model can be provided. In particular, even when a vanishing model is made by combining a large number of components, it is possible to easily and stably achieve the accuracy.
[Brief description of the drawings]
FIG. 1 is a perspective view of a model 1 and a model 2 of a vanishing model 10 according to the present invention, and a solid body 3 for combining them.
FIG. 2 is a cross-sectional view showing an example of a state in which a binding solid 3 is inserted into a hole 1a or 2a.
FIG. 3 is a partial cross-sectional view showing a state where the combined models 1 and 2 are pressed by a pressing machine.
[Explanation of symbols]
1, 2 foamed polystyrene mold 1a, 2a joining surface 1b, 2b hole 3 solid for binding (rod-shaped wax)
4 pressing machine 5 plate 10 vanishing model

Claims (19)

A method of obtaining a vanishing model by combining a plurality of separated components,
A method for assembling a vanishing model, characterized in that a solid matter that can be eliminated by a molten metal is fitted into a concave portion provided in each of the above-mentioned components to connect the respective components. The method according to claim 1, wherein the solid is wax. The method according to claim 1, wherein the recess is formed by machining by a program. 2. The method according to claim 1, further comprising bonding and joining the joining surfaces of the components. The method of assembling a vanishing model according to claim 4, wherein after the bonding, the vanishing model material is joined while being pressed within an elastic range of a compressive strength of the vanishing model material. A method of performing casting using a vanishing model obtained by combining a plurality of separated components,
Each component is joined by fitting a solid that can be eliminated by the molten metal into a concave portion provided at a position corresponding to each component,
A casting method characterized by casting a molten metal into the combined vanishing model. The casting method according to claim 6, wherein the solid is wax. The casting method according to claim 6, wherein the temperature of the molten metal is 600C or higher. The casting method according to claim 6, wherein the solid is wax, and a total volume ratio of the wax used to the molten metal volume is such that it does not substantially affect the casting. The casting method according to claim 9, wherein the volume ratio is 15%. The casting method according to any one of claims 6 to 9, wherein, before casting the molten metal, an adhesive is applied to a joint surface of each of the components to bond the components. The casting method according to claim 11, wherein the bonding is performed while applying pressure within an elastic range of the compressive strength of the disappearing model material. A vanishing model assembled by combining a plurality of separated components,
A vanishing model, characterized in that a solid that can be vanished by a molten metal is fitted into a recess provided at a position corresponding to each component to be coupled. 14. The vanishing model according to claim 13, wherein the recess is formed by machining by a program. The casting method according to claim 13, wherein joining surfaces of the respective components are adhered to each other. A binding solid to be provided in the vanishing model assembled by combining a plurality of separated components,
The solid matter for binding, wherein the solid matter is a solid matter that can be eliminated by a molten metal. 17. The binding solid of claim 16, wherein the solid is a wax. 17. The binding solid of claim 16, wherein the solid comprises a wax-based material selected from the group consisting of paraffin, paraffin wax, wood wax, microcrystalline wax, petrolatum, montan wax, and wax. 17. The solid according to claim 16, wherein the solid is a wax having a melting point of 35 to 150 [deg.] C.

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