Dimension evaluation method, dimension evaluation device, and dimension evaluation program

Abstract

A dimension evaluation method, dimension evaluation device, and dimension evaluation program according to the present invention use a controller connected to an input unit and an output unit. The input unit accepts input of X-ray CT data of a part corresponding to a cast product in the manufacturing process of the cast product. The controller generates difference data indicating a difference between a first shape and a second shape on the basis of the X-ray CT data, where one or a plurality of processes included in the manufacturing process are defined as target processes, the shape of the part before the target processes is defined as the first shape, and the shape of the part after the target processes is defined as the second shape. The output unit outputs the difference data.

Description

Dimension evaluation method, dimension evaluation device, and dimension evaluation program

[0001] The present disclosure relates to a dimension evaluation method, a dimension evaluation device, and a dimension evaluation program.

[0002] Patent Document 1 discloses a method for observing the behavior of molten metal in a mold by irradiating X-rays during casting. According to this method for observing the inside of the mold, X-ray transmission materials excellent in X-ray transmission are disposed on opposite wall portions of the mold where X-rays are irradiated, and the X-rays are transmitted into the mold to observe the behavior of the molten metal.

[0003] Japanese Patent Application Laid-Open No. 2008-207193

[0004] Since the method described in Patent Document 1 does not measure the dimensions of the hollow portion of the mold at the time of mold molding and firing, it is impossible to measure the deformation of the shape of the portion corresponding to the cast product. Therefore, there is a problem that it is impossible to evaluate the degree of deformation of the shape of the portion corresponding to the cast product, which is necessary to stabilize the dimensions of the mold.

[0005] The present disclosure has been made in view of the above problems. An object thereof is to provide a dimension evaluation method, a dimension evaluation device, and a dimension evaluation program capable of evaluating the degree of deformation of the shape of a portion corresponding to a cast product, which is necessary to stabilize the dimensions of the mold.

[0006] The dimension evaluation method, dimension evaluation device, and dimension evaluation program according to the present disclosure use a controller connected to an input unit and an output unit. X-ray CT data of a portion corresponding to a cast product in the manufacturing process of the cast product is input to the input unit. The controller sets one or more processes included in the manufacturing process as target processes, the shape of the portion before the target process as the first shape, and the shape of the portion after the target process as the second shape, and generates difference data indicating the difference between the first shape and the second shape based on the X-ray CT data. The output unit outputs the difference data.

[0007] The target process may include at least any one of a mold shaping process, a dewaxing process, a firing process, and a casting process.

[0008] The controller may also generate difference data by aligning the first shape and the second shape based on the shape of interest formed on the surface of the part.

[0009] The shape of interest may be a flat surface.

[0010] The shape of interest may be a convex shape that protrudes from the surface of the part.

[0011] The size of the convex shape may be determined based on the resolution in the X-ray CT data, or the surface roughness of the shape of the portion.

[0012] If the target process begins with the mold manufacturing process, the controller may acquire the first shape based on X-ray CT data relating to the shape of the wax mold surface.

[0013] The controller may acquire the first shape based on X-ray CT data relating to the shape of the hollow portion of the mold before dewaxing, if the target process begins with the dewaxing process.

[0014] If the target process begins with the firing process, the controller may acquire the first shape based on X-ray CT data relating to the shape of the hollow portion of the mold before firing.

[0015] If the target process begins with the casting process, the controller may acquire the first shape based on X-ray CT data relating to the shape of the hollow portion of the mold before casting.

[0016] This disclosure provides a dimensional evaluation method, a dimensional evaluation apparatus, and a dimensional evaluation program that can evaluate the degree of deformation of the shape of the part corresponding to the casting, which is necessary for stabilizing the dimensions of the mold.

[0017] This is a block diagram showing the configuration of a dimensional evaluation device according to an embodiment of this disclosure. This is a flowchart showing the processing procedure of the dimensional evaluation device. This is a flowchart showing an example of the manufacturing process of a casting. This is a perspective view showing an example of a casting. This is a front view showing an example of a casting. This is a diagram showing an example of deformation in the cross-section of a part corresponding to a casting.

[0018] Several exemplary embodiments will be described below with reference to the drawings. Common parts in each drawing are denoted by the same reference numerals, and redundant explanations will be omitted.

[0019] [Configuration of the Dimensional Evaluation Device] Figure 1 is a block diagram showing the configuration of a dimensional evaluation device according to an embodiment of the present disclosure. The dimensional evaluation device 20 comprises an input unit 21, an output unit 23, and a controller 25. The controller 25 is connected to the input unit 21 and the output unit 23 so as to be able to communicate with them.

[0020] The input unit 21 receives X-ray CT data of the part of the casting corresponding to the casting during the casting manufacturing process. Figure 1 shows the input unit 21 connected to the X-ray CT scanner (CT).

[0021] An X-ray CT scanner (CT) irradiates an object TG (transient gravitational) with X-rays and acquires a two-dimensional transmission image of the object TG. For example, as shown in Figure 1, an object TG is placed between an irradiation source (XR) and an imaging unit (RV). X-rays are irradiated from the irradiation source (XR), and a two-dimensional transmission image is acquired by the imaging unit (RV). The two-dimensional transmission image contains information such as X-ray absorption and scattering by the object TG. Multiple two-dimensional transmission images are then acquired by rotating the object TG and irradiating it with X-rays from different angles. By analyzing these multiple two-dimensional transmission images, the three-dimensional density distribution of the object TG is calculated.

[0022] The spatial resolution of the three-dimensional density distribution of an object (TG) can vary depending on the performance of the X-ray CT scanner (CT). A typical X-ray CT scanner can achieve a resolution of several tens of microns.

[0023] The three-dimensional density distribution of an object TG is represented by a set of voxels. Here, a "voxel" is the smallest unit of data used to represent a three-dimensional object in a computer. For example, a voxel may be a cube, which is the unit element of an orthogonal grid. Alternatively, a voxel may be any other polyhedron. On a computer, a component containing multiple structural elements is represented as a set of voxels, and each voxel has a scalar value. By giving the density of the object TG as a scalar value, the entire set of voxels can represent the three-dimensional density distribution of the object TG.

[0024] Regarding the acquisition of X-ray CT data for the "part corresponding to the casting," it is important to note that the target object's TG may differ depending on at which stage of the casting manufacturing process the X-ray CT data is acquired.

[0025] For example, consider a case where the manufacturing process for a casting includes a mold making process, a dewaxing process, a firing process, and a casting process. Figure 3 is a flowchart showing an example of the manufacturing process for a casting.

[0026] Step S201, the "mold forming process," is a process in which a refractory slurry is poured around a model made of wax to form a mold of a predetermined thickness around the wax model.

[0027] Step S203, the "dewaxing process," is a process in which the wax mold is heated to melt the wax and remove the wax while leaving the mold intact.

[0028] Step S205, the "firing process," is a process in which the mold is fired to increase its strength.

[0029] Step S207, the "casting process," is the process of pouring metal or the like into a mold to form a casting.

[0030] Before the "mold making process," the object TG becomes a wax model. Alternatively, the shape of the object TG may be obtained based on the design data of the casting, instead of using X-ray CT data. The surface shape of the wax model corresponds to the shape of the "part corresponding to the casting."

[0031] After the "mold forming process" and before the "dewaxing process," the object TG becomes a mold and a wax mold formed from refractory slurry. The shape of the interface between the mold and the wax mold corresponds to the shape of the "part corresponding to the casting." However, since the mold also forms runners through which the metal flows during casting, the interface between the mold and the wax mold does not directly match the shape of the "part corresponding to the casting."

[0032] After the "dewaxing process" and before the "firing process," the object TG becomes a mold formed from refractory slurry. At this stage, the wax mold has been removed, so the mold has a hollow section. The shape of the inner surface of the hollow section of the mold corresponds to the shape of the "part corresponding to the casting."

[0033] After the "firing process" and before the "casting process," the object TG becomes the mold after firing. The shape of the inner surface of the hollow part of the mold corresponds to the shape of the "part corresponding to the casting."

[0034] After the "casting process," the object TG becomes the casting itself. The surface shape of the casting corresponds to the shape of the "part corresponding to the casting."

[0035] Thus, although the object TG may change depending on the stage of the casting manufacturing process, the shape of the "part corresponding to the casting" can be defined for the object TG at each stage.

[0036] In the following explanation, "parts corresponding to the casting" refers to parts whose shape can be defined for an object TG that may change depending on the stage of the casting manufacturing process. Therefore, "parts corresponding to the casting" may include not only parts related to the casting itself, but also parts such as wax molds and casting molds that appear in the process of manufacturing the casting.

[0037] Furthermore, the input unit 21 may be connected to the X-ray CT scanner (CT) wirelessly or via a wired connection. Also, the input unit 21 is not limited to being directly connected to the X-ray CT scanner (CT). The input unit 21 may acquire X-ray CT data obtained by the X-ray CT scanner (CT) by reading it from an external storage device (not shown). The input unit 21 may be integrated with the X-ray CT scanner (CT).

[0038] The output unit 23 outputs various types of information generated by the controller 25, which will be described later. For example, the output unit 23 outputs differential data generated by the controller 25. In addition, the output unit 23 may output information generated based on the differential data.

[0039] The output unit 23 may be connected to an external storage device (not shown) or a display device (not shown). The information output from the output unit 23 may be presented to the user by a display device (not shown) or the like.

[0040] The controller 25 is a general-purpose computer equipped with a CPU (Central Processing Unit), memory, and an input / output unit. The controller 25 has a computer program (dimensional evaluation program) installed for functioning as the dimensional evaluation device 20. By executing the computer program, the controller 25 functions as one of the multiple information processing circuits (251, 253, 255) provided by the dimensional evaluation device 20. The computer program may be stored on a storage medium readable and writable by the computer, or it may be distributed via a telecommunications line.

[0041] This disclosure provides an example of implementing multiple information processing circuits (251, 253, 255) using software. However, it is also possible to configure the information processing circuits (251, 253, 255) by preparing dedicated hardware for each of the information processing operations described below. Alternatively, the multiple information processing circuits (251, 253, 255) may be configured using separate hardware.

[0042] As shown in Figure 1, the controller 25 includes a plurality of information processing circuits (251, 253, 255), namely a shape acquisition unit 251, a positioning unit 253, and a difference calculation unit 255.

[0043] The shape acquisition unit 251 acquires the shape (first shape) of the "part corresponding to the casting" before the target process. The shape acquisition unit 251 also acquires the shape (second shape) of the "part corresponding to the casting" after the target process. Here, the "target process" refers to one or more processes included in the manufacturing process. For example, the "target process" may include at least one of the following: the mold making process, the dewaxing process, the firing process, and the casting process.

[0044] For example, the shape acquisition unit 251 may acquire the first shape and the second shape based on the X-ray CT data. Specifically, the shape acquisition unit 251 may acquire the three-dimensional density distribution of the object TG based on the X-ray CT data and acquire the shape of the surface of the object TG.

[0045] Also, when the target process starts from the mold shaping process, the shape acquisition unit 251 may acquire the first shape based on the X-ray CT data related to the shape of the surface of the wax mold. Further, the shape acquisition unit 251 may acquire the first shape based on the design data of the casting. Specifically, the shape acquisition unit 251 may read and acquire the design data of the casting from an external storage device (not shown). Also, the shape acquisition unit 251 may acquire the design data of the casting from external CAD (Computer Aided Design) software. The method of acquiring the design data is not limited to the examples given here.

[0046] When the target process starts from the dewaxing process, the shape acquisition unit 251 may acquire the first shape based on the X-ray CT data related to the shape of the hollow part of the mold before dewaxing. Also, when the target process ends with the dewaxing process, the shape acquisition unit 251 may acquire the first shape based on the X-ray CT data related to the shape of the hollow part of the mold.

[0047] When the target process starts from the firing process, the shape acquisition unit 251 may acquire the first shape based on the X-ray CT data related to the shape of the hollow part of the mold before firing. Also, when the target process ends with the firing process, the shape acquisition unit 251 may acquire the first shape based on the X-ray CT data related to the shape of the hollow part of the mold after firing.

[0048] When the target process starts from the casting process, the shape acquisition unit 251 may acquire the first shape based on the X-ray CT data related to the shape of the hollow part of the mold before casting. Also, when the target process ends with the casting process, the shape acquisition unit 251 may acquire the first shape based on the X-ray CT data related to the shape of the casting itself.

[0049] The alignment unit 253 aligns the first shape and the second shape. For example, the alignment unit 253 aligns the first shape and the second shape using a target shape formed on the surface of the "part corresponding to the casting" as a reference.

[0050] Specifically, the alignment unit 253 extracts a shape of interest from the first shape and also extracts a shape of interest from the second shape. Then, the alignment unit 253 moves one of the first shape and the second shape relative to the other so that both the shape of interest included in the first shape and the shape of interest included in the second shape overlap. The movement includes translation and rotation.

[0051] The "shape of interest" can refer to various shapes. For example, the "shape of interest" may be a flat surface. Flat surfaces are easily identifiable in X-ray CT data and can therefore be used as a reference for alignment.

[0052] The "shape of interest" may be a convex shape that protrudes from the surface of the "part corresponding to the casting." More specifically, if the object TG is a wax mold, the shape of interest may be a convex shape that protrudes from the surface of the wax mold. The shape of interest may also be a convex shape newly added to the wax mold.

[0053] If the object TG is a mold, the shape of interest may be a convex shape projecting from the center of the hollow portion of the mold outwards on the surface of the hollow portion. Alternatively, a convex shape newly added to the mold may be the shape of interest.

[0054] If the object TG is a casting, the convex shape protruding from the surface of the casting may be designated as the shape of interest.

[0055] The size of the convex shape may be set based on the resolution in the X-ray CT data, or the surface roughness of the shape of the "part corresponding to the casting." In particular, the size of the convex shape may be set to be larger than the resolvable length scale determined by the resolution in the X-ray CT data.

[0056] The difference calculation unit 255 generates difference data that shows the difference between the first shape and the second shape. More specifically, it calculates the difference in surface position between the aligned first shape and the second shape.

[0057] Refer to Figures 4-6 for an explanation of how to calculate the difference data.

[0058] Figure 4 is a perspective view showing an example of a casting. Figure 5 is a front view showing an example of a casting. Figures 4 and 5 show a casting having parts P1 to P3. Parts P1 and P3 have a rectangular parallelepiped shape, with their bottom surfaces arranged parallel to the xz plane. Part P2 has a plate-like shape and connects the bottom surface of part P1 and the top surface of part P3.

[0059] For example, after manufacturing the castings shown in Figures 4 and 5, part P2 is separated from parts P1 and P3, and part P2 becomes the final product. Parts P1 and P3 correspond to the runners through which molten metal flows into the mold. The shapes of the castings shown in Figures 4 and 5 are merely examples.

[0060] For example, the alignment unit 253 aligns the first shape and the second shape using a flat surface on the upper surface of part P3 as the shape of interest. Alternatively, the alignment unit 253 may align the first shape and the second shape using a convex shape newly provided separately on parts P1 to P3 as the shape of interest.

[0061] The alignment unit 253 may perform alignment using one shape of interest, or it may perform alignment using multiple shapes of interest.

[0062] Figure 6 shows an example of deformation in the cross-section of a part corresponding to a casting. In Figure 6, the surface shapes of parts P1 to P3 in the cross-section in the yz plane are shown by curves C1 and C2. For example, curve C1 corresponds to the first shape, and curve C2 corresponds to the second shape. Regions with z coordinates smaller than curve C1 or curve C2 are regions where parts P1 to P3 exist.

[0063] Due to the alignment performed by the alignment unit 253, curves C1 and C2 coincide at part P3. On the other hand, at part P2, a misalignment occurs between curves C1 and C2. This misalignment represents a change in shape before and after the target process.

[0064] The difference calculation unit 255 calculates the difference between curve C1 and curve C2. For example, it calculates the difference between the z coordinate of curve C1 and the z coordinate of curve C2 at a predetermined y-coordinate position as difference data. In this way, the difference calculation unit 255 may calculate the difference in z coordinates for each x and y coordinate and use it as difference data.

[0065] In this way, the difference calculation unit 255 generates difference data, allowing the user to refer to the difference data and consider where in the part of the casting the shape changes before and after the target process are most likely to occur. This enables the evaluation of the degree of deformation of the part of the casting that is necessary to stabilize the dimensions of the mold.

[0066] [Processing Procedure of the Dimensional Evaluation Device] Figure 2 is a flowchart showing the processing procedure of the dimensional evaluation device.

[0067] In step S101, the shape acquisition unit 251 acquires the first shape.

[0068] In step S103, the shape acquisition unit 251 acquires the second shape.

[0069] In step S105, the alignment unit 253 extracts the shape of interest from the first shape and the second shape.

[0070] In step S107, the alignment unit 253 performs alignment of the first shape and the second shape.

[0071] In step S109, the difference calculation unit 255 generates difference data.

[0072] In step S111, the output unit 23 outputs the difference data.

[0073] [Effects of the Embodiment] As described in detail above, the dimensional evaluation method, dimensional evaluation device, and dimensional evaluation program according to this disclosure use a controller connected to an input unit and an output unit. X-ray CT data of the part of the casting corresponding to the manufacturing process of the casting is input to the input unit. The controller takes one or more processes included in the manufacturing process as the target process, the shape of the part before the target process as the first shape, and the shape of the part after the target process as the second shape, and generates difference data showing the difference between the first shape and the second shape based on the X-ray CT data. The output unit outputs the difference data.

[0074] This allows for the evaluation of the degree of deformation of the part of the mold corresponding to the casting, which is necessary to stabilize the dimensions of the mold. For example, by referring to the difference data, users can consider where in the part of the casting that changes in shape before and after the relevant process are likely to occur. As a result, they can take measures such as changing the runners in the casting manufacturing process, which leads to the stabilization of the mold dimensions.

[0075] The target process may include at least one of the following: mold making, dewaxing, firing, and casting. This allows for the evaluation of the degree of deformation of the part of the casting corresponding to each step of the lost-wax precision casting process. For example, the magnitude of deformation can be evaluated for each step, and countermeasures can be pinpointed and applied to steps with large deformations.

[0076] The controller may align the first and second shapes based on the shape of interest formed on the surface of the part, and generate difference data. This makes it easy to compare the first and second shapes.

[0077] The shape of interest may be a flat surface. This allows for easy comparison of the first and second shapes using the flat surface as a reference. Furthermore, it allows for evaluation of the degree of deformation using the flat surface as a reference.

[0078] The shape of interest may be a convex shape protruding from the surface of the part. This makes it easy to compare the first shape and the second shape with respect to a reference position where the convex shape is provided. Furthermore, it is possible to evaluate the degree of deformation that has occurred relative to the reference position.

[0079] The size of the convex shape may be set based on the resolution in the X-ray CT data or the surface roughness of the partial shape. This makes it easier to extract the convex shape from the X-ray CT data. As a result, it becomes easier to compare the first shape and the second shape.

[0080] If the target process begins with the mold making process, the controller may acquire a first shape based on X-ray CT data relating to the surface shape of the wax mold. This makes it possible to evaluate the degree of deformation that has occurred based on the design data of the casting.

[0081] If the target process begins with the dewaxing process, the controller may acquire a first shape based on X-ray CT data relating to the shape of the hollow portion of the mold before dewaxing. This makes it possible to evaluate the degree of deformation that has occurred based on the shape of the surface of the wax mold.

[0082] If the target process begins with the firing process, the controller may acquire a first shape based on X-ray CT data relating to the shape of the hollow portion of the mold before firing. This makes it possible to evaluate the degree of deformation that has occurred based on the shape of the hollow portion of the mold before firing.

[0083] If the target process begins with the casting process, the controller may acquire a first shape based on X-ray CT data relating to the shape of the hollow portion of the mold before casting. This makes it possible to evaluate the degree of deformation that has occurred based on the shape of the hollow portion of the mold before casting.

[0084] Each of the functions described in the embodiments above may be implemented by one or more processing circuits. These processing circuits may include programmed processors, electrical circuits, and further may include devices such as application-specific integrated circuits (ASICs), or circuit components arranged to perform the described functions.

[0085] According to this disclosure, the degree of deformation of the shape of the part corresponding to the casting can be evaluated, and as a result, the user's workload when stabilizing the dimensions of the mold can be reduced. Therefore, for example, it can contribute to United Nations Sustainable Development Goal (SDG) 8, "Promote inclusive and sustainable economic growth and full and productive employment and decent work for all."

[0086] Although several embodiments have been described, it is possible to modify or transform the embodiments based on the above disclosure. All components of the above embodiments, and all features described in the claims, may be taken individually and combined, provided that they do not conflict with each other.

[0087] The entire contents of Japanese Patent Application No. 2024-167403 (Filing Date: September 26, 2024) are incorporated herein by reference.

[0088] 20 Dimensional evaluation device 21 Input unit 23 Output unit 25 Controller 251 Shape acquisition unit 253 Alignment unit 255 Difference calculation unit CT X-ray CT device P1-P3 Body part RV Imaging unit TG Object XR Irradiation source

Claims

1. A dimensional evaluation method for controlling a controller connected to an input unit and an output unit, wherein the input unit receives X-ray CT data of a portion of a casting in the manufacturing process of the casting; the controller generates difference data showing the difference between the first and second shapes based on the X-ray CT data, with one or more processes included in the manufacturing process as the target process, the shape of the portion before the target process as the first shape, and the shape of the portion after the target process as the second shape; and the output unit outputs the difference data.

2. The dimensional evaluation method according to claim 1, wherein the target process includes at least one of the following: a mold making process, a dewaxing process, a firing process, and a casting process.

3. The dimensional evaluation method according to claim 1, wherein the controller aligns the first shape and the second shape with respect to a shape of interest formed on the surface of the portion, and generates the difference data.

4. The dimensional evaluation method according to claim 3, wherein the shape of interest is a flat surface.

5. The dimensional evaluation method according to claim 3, wherein the shape of interest is a convex shape protruding from the surface of the portion.

6. The dimensional evaluation method according to claim 5, wherein the size of the convex shape is set based on the resolution in the X-ray CT data or the surface roughness of the shape of the portion.

7. The dimensional evaluation method according to claim 1, wherein the controller acquires the first shape based on the X-ray CT data relating to the shape of the surface of the wax mold when the target process starts from the mold making process.

8. The dimensional evaluation method according to claim 1, wherein the controller acquires the first shape based on the X-ray CT data relating to the shape of the hollow portion of the mold before dewaxing, when the target process begins with the dewaxing process.

9. The dimensional evaluation method according to claim 1, wherein the controller acquires the first shape based on the X-ray CT data relating to the shape of the hollow portion of the mold before firing, when the target process begins with the firing process.

10. The dimensional evaluation method according to claim 1, wherein the controller acquires the first shape based on the X-ray CT data relating to the shape of the hollow portion of the mold before casting, when the target process begins with the casting process.

11. A dimensional evaluation device comprising an input unit, an output unit, and a controller, wherein the input unit receives X-ray CT data of a portion of a casting in the manufacturing process of the casting; the controller generates difference data showing the difference between the first and second shapes based on the X-ray CT data, with one or more processes included in the manufacturing process as the target process, the shape of the portion before the target process as the first shape, and the shape of the portion after the target process as the second shape; and the output unit outputs the difference data.

12. A dimensional evaluation program executed by a controller connected to an input unit and an output unit, comprising: a step of inputting X-ray CT data of a portion of a casting in the manufacturing process of a casting via the input unit; a step of generating difference data showing the difference between the first shape and the second shape based on the X-ray CT data, with one or more processes included in the manufacturing process being the target process, the shape of the portion before the target process being the first shape, and the shape of the portion after the target process being the second shape; and a step of outputting the difference data via the output unit.

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