JP2007061826A - Method for casting cast product by evaporative pattern casting method, and method for manufacturing metallic mold for forming foamed product pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an evaporative pattern casting method so that a cast product goes in a targeted size or permissible error range, and a method for manufacturing a metallic mold for forming the foamed pattern. <P>SOLUTION: A method for casting the cast product by the evaporative pattern casting method is contained of: (a) a casting simulation process for cast product, performing the simulation of the casting for cast product with the evaporative pattern casting method by inputting data related to three-dimensional size of the foamed product pattern corresponding to the targeted size, material data for foamed product and data of a gating system and a molten metal pouring method, into a computer, containing the simulations for molten metal flowing, the solidification of the molten metal and the deformation of the cast product with the solidification; (b) a process for deciding a last three-dimensional size of the foamed product pattern while considering the deformation of the cast product in the above casting simulation process for cast product and a contraction rule of the relation between the cast product and the foamed product pattern; (c) a process for manufacturing the foamed product pattern having the final three-dimensional size; and (d) a process for casting the cast product with the evaporative pattern casting method by using the foamed product pattern manufactured with the above method. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a casting casting method using a disappearance model casting method, and a method for manufacturing a foam product model molding die for molding a foam product model used in the disappearance model casting method.

  The foam product model used in the disappearance model casting method is manufactured as follows. First, the granular foam material beads are sealed in a container, and steam is blown into the foam to be pre-foamed (primary foaming), and then the pre-foamed beads are filled into a mold cavity for producing a foam product model and cured. Let

  The material beads are mainly composed of PMMA (polymethyl methacrylate), and polystyrene or the like is added thereto. The mixing ratio of these components varies depending on the manufacturer. In the pre-expansion, the material beads are expanded with an expansion ratio of about 40 times. In some cases (for example, when producing a thin casting), the expansion ratio may be increased to about 45 times. However, if the foaming rate is increased in this way, the foamed model hardness decreases, and the foamed model tends to be deformed when it is filled with sand, which is not suitable for manufacturing a thick casting.

  When a casting is manufactured by the vanishing model casting method using the foamed product model formed in this way, the shrinkage of the casting manufactured differs depending on the composition of the foam material beads and the difference in the expansion ratio.

  Further, an actual mold cavity is manufactured in consideration of a shrinkage allowance when the poured metal is solidified to become a product casting (that is, using an extension scale). The shrinkage allowance varies depending on the metal. The scale of the relationship between the casting and the model is 5/1000 to 8/1000. Further, there is a shrinkage of the foamed product model in the relationship between the foamed product model and its molding die, and the scale of 3/1000 to 10/1000 is used.

  In this way, it is confirmed whether or not the cast product cast using the extender has a target shape and size, or is within an allowable error range. However, if the product is not the target size or is out of the tolerance range, the model size needs to be corrected, so the mold cavity that molds the foam product model is expanded or the cavity is filled It is difficult to make a mold again.

  Even if casting is performed using a certain scale as described above, there may be differences in the shrinkage allowance depending on the casting part, and the casting product does not fit within the tolerance, and the mold for the foam product model is remanufactured. There was often a need to do that. The difference in the contraction allowance depending on the part is, for example, a bifurcated pipe, one of the branched pipe parts is substantially linear, and the other pipe part is curved in an arc shape. This is a cast pipe product. In this case, there is a difference in the shrinkage allowance between the convex part and the concave part of the pipe part that is curved in an arc shape.

  The invention described in the following Patent Document 1 (Japanese Patent Laid-Open No. 4-361849) relates to a cast product manufacturing system used when casting a press die or the like by a full mold method, and is designed with sufficient consideration of casting conditions when creating CAD data. The purpose is to provide a cast product manufacturing system capable of performing work management in a casting zone (casting process).

  Non-Patent Document 1 ("Jacto News No. 558 (June 20, 2003)" (Japan Foundry Technology Association)) is a commercially available computer that inputs data on the pouring plan, pouring method, etc. into a computer. Teaching to observe the flow of molten metal, solidification, and deformation simulation by finite element method using software, and to observe the state of molten metal flow, the presence or absence of shrinkage cavities, and cracks / deformation during casting solidification.

  However, both these documents do not disclose or suggest a casting simulation using the disappearance model casting method.

There is a demand for a method for producing a foam product model mold that can reduce or eliminate the need to remanufacture a mold for a foam product model in the disappearance model casting method, and a casting casting method using the method. .
JP-A-4-361849 “Jacto News No. 558 (June 20, 2003)” (Japan Foundry Technology Association)

  The present invention solves the problem that the cast product cast by the disappearance model casting method does not fall within the allowable error, or the problem that the mold for the foam product model needs to be remanufactured without being within the allowable error. It is another object of the present invention to provide a disappearance model casting method for making a cast product fall within a target dimension or an allowable error range thereof, and a method for manufacturing a mold for molding a foam product model used in the method.

  In order to achieve the above object, in one embodiment, the present invention is a method of casting a casting having a target dimension by a vanishing model casting method using a foamed product model, and (a) corresponds to the target dimension. This is a process of inputting data relating to the three-dimensional dimensions of the foamed product model, data relating to the material of the foamed product model, and data relating to the pouring plan and the pouring method to a computer and simulating casting casting by the disappearance model casting method. The simulation includes a casting casting simulation process including simulation of molten metal flow, solidification of molten metal, and casting deformation caused by the solidification, and (b) the casting deformation in the casting casting simulation process, and the relationship between the casting and the foam product model. Determining the final three-dimensional dimension of the foam product model in consideration of the scale; and (c) the final three-dimensional dimension A step of fabricating a foamed product model, a (d) casting the casting method according evaporative pattern casting method comprising a step of casting the casting by evaporative pattern casting using the fabricated foamed product model.

  In this embodiment, the foamed product model can be manufactured from the foamed material block, thereby enabling casting by the disappearing model casting method without using a mold for the foamed product model.

In one embodiment, the present invention is a method of manufacturing a mold for molding a foam product model used in a disappearance model casting method for casting a casting having a target dimension, and (a) the foam corresponding to the target dimension A step of inputting data relating to the three-dimensional dimensions of the product model, data relating to the raw material of the foamed product, and data relating to the pouring gate method and the pouring method to a computer and performing a casting casting simulation by the disappearance model casting method, The simulation includes a casting casting simulation process including simulation of molten metal flow, solidification of the molten metal and casting deformation, and (b) foaming in consideration of the deformation of the casting in the casting casting simulation process and the scale of the relationship between the casting and the foam product model. A step of determining a final three-dimensional dimension of the product model; And (d) a step of trial casting a casting by the vanishing model casting method using the produced foamed product model, (e) a step of measuring three-dimensional data of the trial casting and (f) the measurement Determining whether the measured three-dimensional data is within the tolerance range of the target dimension; and (g) if the measured three-dimensional data is within the tolerance range of the target dimension, (H) the step of inputting the data of the final three-dimensional dimension into the controller of the NC machine tool and cutting the mold base by the NC machine tool to produce a mold having the cavity of the final three-dimensional dimension; A step of molding a foam product model using the manufactured mold, (i) a step of casting a casting by a vanishing model casting method using the molded foam product model, and (j) of the cast casting Measure 3D data (K) determining whether the three-dimensional data measured in step (j) is within an allowable error range of the target dimension; and (l) the three-dimensional data measured in step (k). If it is within the tolerance range of the target dimension, the method is terminated. If it is not within the tolerance range, the three-dimensional data of the casting inputted to the controller is corrected, and the NC is based on the corrected three-dimensional data. Modifying the final three-dimensional dimension of the mold cavity with a machine tool;
A mold manufacturing method including

  In this aspect of the mold manufacturing method, in several stages, it is checked whether the actually measured three-dimensional data is within the tolerance range of the target dimension, so the possibility of remanufacturing the mold is extremely low. be able to.

  In one embodiment, the present invention provides a step of molding a foam product model using the mold manufactured in the above-described mold manufacturing method, and a casting by a vanishing model casting method using the molded foam product model. A casting casting method including a step of casting.

  A casting simulation by a computer which is a main part of the present invention will be described. The casting simulation is done using a computer and software developed in connection with the present invention.

  First, as input parameters, data related to the three-dimensional dimensions of the foam product model corresponding to the target (design) dimensions of the product casting, data related to the material of the foam product model, and data related to the gate design and pouring method are input to the computer. To do. Data other than these data can be input as required.

  The simulation is performed in the order of molten metal flow analysis, solidification analysis, and deformation analysis. The molten metal flow analysis is to obtain the process of the molten metal entering the cavity, the time when the molten metal has entered the cavity, the pressure state and the temperature distribution at the time of filling the molten metal into the cavity. Perform solidification analysis using the temperature distribution at the time of cavity filling obtained by this molten metal flow analysis, and then perform deformation analysis due to thermal stress from the solidification time obtained by solidification analysis and the product temperature distribution during solidification Is. That is, the hot water flow is performed to analyze how the cavities are filled, and for this purpose, (1) filling time, (2) whether the hot water flow is turbulent or rectified, (3) Consider three factors of the order of filling positions. After the filling analysis is performed, thermal analysis is performed focusing on solidification, and deformation analysis due to thermal stress in the thermal analysis is performed.

  A casting simulation of the disappearance model casting method was performed under the following conditions using a mesh model with a minimum mesh interval of 4.5 by the finite element method using the above software.

Conditions Shape of cast product: Cylindrical (length (height) 80mm, outer diameter 250mm, minimum wall thickness 3.5mm)
Product material: FCD450
Results The results of the casting simulation were as follows.

1. Analysis of molten metal flow The process of molten metal entering the product, the time that it entered, and the pressure state at the time of filling the molten metal cavity were obtained. The pouring time was 7.07 seconds, and the molten metal pressure (product part) was 0.07 to 0.10 MPa.

(If the pouring time is too long, there may be a defect that the hot water does not completely enter the cavity. Based on the results of the simulation, it is possible to make a casting plan in which the molten metal can easily enter.)
2. The solidification time, which is the time from when the hot water has completely entered the solidification analysis cavity (liquid state) to when the hot water solidifies (becomes solid state), was 120 seconds.

A portion where the porosity amount was 0.2% or more was slightly seen in the runway.

(Defects such as shrinkage cavities are more likely to occur in the part where the product solidifies at the end, and the presence of porosity greatly affects the product strength. It is also possible to make a casting plan that does not easily occur.)
3. The amount of variation in the outer periphery of the deformation analysis product was the largest and was distorted by 0.021 mm.

Thermal stress is generated in the process of solidifying the product, and the product is deformed by the stress, but if it is possible to know in advance how much the product will be deformed by simulation, it is possible to produce a foam model mold that anticipates the amount of deformation. It is.

  The data after the deformation analysis is converted into STL data (three-dimensional CAD intermediate file data) by simulation software.

  The variation amount of 0.021 mm exceeds the allowable error of 0.015 mm. Considering this, the dimensions of the foam product model that can reduce this error (within the allowable error range) are considered. Such dimensions can be determined empirically. Alternatively, the size of the foam product model may be changed and / or other parameters input to the computer may be changed, and the computer simulation may be performed again until the error falls within the allowable error range. In this way, the three-dimensional dimension of the foam product model is determined so that the variation amount falls within the allowable error range, and the three-dimensional dimension of the determined foam product model and the scale of the relationship between the casting and the foam product model are taken into consideration. Determine the final 3D dimensions of the model.

  Next, a method for producing a foamed product model having the final three-dimensional dimensions will be described.

  As one of the methods, a foamed product model having a final three-dimensional dimension is formed by putting granular foam material beads into a sealed container and blowing steam to form a foam block having an appropriate foaming ratio, and processing the foam block. To manufacture.

  As another method, the foamed product model can be molded using a foamed product model molding die manufactured by using a method for manufacturing a mold for molding a foamed product model, which will be described later.

  Next, a casting can be manufactured by the vanishing model casting method using the manufactured foamed product model.

Here, the aspect of the method of manufacturing the metal mold | die which shape | molds the foamed product model according to this invention is demonstrated. This aspect is a method of manufacturing a mold for molding a foam product model used in a disappearance model casting method for casting a casting having a target dimension.
(A) Casting by the disappearance model casting method by inputting data relating to the three-dimensional dimensions of the foamed product model corresponding to the target size, data relating to the raw material of the foamed product, and data relating to the pouring plan and pouring methods to a computer. A casting simulation process, the simulation including a casting casting simulation process including simulation of molten metal flow, solidification of molten metal and casting deformation;
(B) determining the final three-dimensional dimensions of the foam product model in consideration of the casting deformation in the casting casting simulation process and the extension of the relationship between the casting and the foam product model;
(C) producing a foam product model of the final three-dimensional dimension;
(D) a step of trial casting a casting by a vanishing model casting method using the produced foamed product model;
(E) a step of measuring three-dimensional data of the prototype cast product,
(F) determining whether the measured three-dimensional data is within an allowable error range of the target dimension;
(G) If the measured three-dimensional data is within an allowable error range of the target dimension, the final three-dimensional data is input to the controller of the NC machine tool, and the mold base is moved by the NC machine tool. Cutting to produce a mold with the final three-dimensional cavity;
(H) forming a foamed product model using the manufactured mold;
(I) a step of casting a casting by a vanishing model casting method using the molded foam product model;
(J) measuring three-dimensional data of the cast casting;
(K) determining whether the three-dimensional data measured in step (j) is within an allowable error range of the target dimension;
(L) If the measured three-dimensional data in step (k) is within the allowable error range of the target dimension, the method is terminated. If not, the three-dimensional data of the casting is input to the controller. And correcting the final three-dimensional dimension of the mold cavity by the NC machine tool based on the corrected three-dimensional data;
A mold manufacturing method including

  Since the steps (a) and (b) are the same as those in the first embodiment, description thereof is omitted.

  In the step (c), the foam block is processed and manufactured as described in the first embodiment. After step (c), proceed to step (d) (prototype casting by vanishing model casting using the produced foamed product model), and further to step (e) (measure the three-dimensional data of the prototype cast) move on.

  In the step (e), the three-dimensional data of the casting is measured with a three-dimensional measuring device. The three-dimensional data measured by the three-dimensional measuring device can be compared with the STL data regarding the amount of mutation for reference. After step (e), the process proceeds to step (f) (determines whether the measured three-dimensional data is within the allowable error range of the target dimension), and then proceeds to (g).

  In the step (g), if the measured three-dimensional data is not within the tolerance range of the target dimension, it is assumed that there is some defect. I do. That is, the process returns to step (a).

  In step (j), the three-dimensional data of the casting is measured with a three-dimensional measuring device. Next, the process proceeds to step (k). Here, it is determined whether or not the three-dimensional data measured in the step (j) is within the allowable error range of the target dimension.

  In step (k), if the measured three-dimensional data is within the allowable error range of the target dimension, the method is terminated. On the other hand, if the measured three-dimensional data is not within the tolerance range of the target dimension, the method proceeds to step (l), where the three-dimensional data of the casting input to the controller is corrected, and the corrected tertiary Based on the original data, the NC machine tool corrects the final three-dimensional dimension of the mold cavity to finish the final process of the mold.

  The foamed product model can be molded using the mold described above, which has been finished, and the cast product can be cast using the molded foamed product model in the disappearance model casting method.

Claims (3)

A method of casting a casting having a target dimension by a vanishing model casting method using a foam product model,
(A) Data relating to the three-dimensional dimensions of the foamed product model corresponding to the target dimensions, data relating to the material of the foamed product model, and data relating to the pouring gate method and the pouring method are input to a computer, and the disappearance model casting method is used. A casting casting simulation process including a simulation of casting flow, solidification of molten metal and casting deformation due to the solidification;
(B) determining the final three-dimensional dimensions of the foam product model in consideration of the casting deformation in the casting casting simulation process and the extension of the relationship between the casting and the foam product model;
(C) producing a foam product model of the final three-dimensional dimension;
(D) a step of casting a casting by a vanishing model casting method using the produced foamed product model;
Casting method by vanishing model casting method including A method for producing a mold for molding a foam product model used in a disappearance model casting method for casting a casting having a target dimension,
(A) Casting by the disappearance model casting method by inputting data relating to the three-dimensional dimensions of the foamed product model corresponding to the target size, data relating to the raw material of the foamed product, and data relating to the pouring plan and pouring methods to a computer. A casting simulation process, the simulation including a casting casting simulation process including simulation of molten metal flow, solidification of molten metal and casting deformation;
(B) determining the final three-dimensional dimensions of the foam product model in consideration of the casting deformation in the casting casting simulation process and the extension of the relationship between the casting and the foam product model;
(C) producing a foam product model of the final three-dimensional dimension;
(D) a step of trial casting a casting by a vanishing model casting method using the produced foamed product model;
(E) a step of measuring three-dimensional data of the prototype cast product,
(F) determining whether the measured three-dimensional data is within an allowable error range of the target dimension;
(G) If the measured three-dimensional data is within an allowable error range of the target dimension, the final three-dimensional data is input to the controller of the NC machine tool, and the mold base is moved by the NC machine tool. Cutting to produce a mold with the final three-dimensional cavity;
(H) forming a foamed product model using the manufactured mold;
(I) a step of casting a casting by a vanishing model casting method using the molded foam product model;
(J) measuring three-dimensional data of the cast casting;
(K) determining whether the three-dimensional data measured in step (j) is within an allowable error range of the target dimension;
(L) If the measured three-dimensional data in step (k) is within the allowable error range of the target dimension, the method is terminated. If not, the three-dimensional data of the casting is input to the controller. And correcting the final three-dimensional dimension of the mold cavity by the NC machine tool based on the corrected three-dimensional data;
A mold manufacturing method including: Forming a foam product model using a mold produced by the method of claim 2;
Casting the casting by vanishing model casting using the molded foam product model;
A casting method comprising: