Apparatus, method, and program for manufacturing metal ingots

Abstract

To provide an apparatus for manufacturing a metal ingot with high quality by applying a melting and casting method.SOLUTION: An apparatus includes a melting furnace and a controller. The melting furnace includes a hearth, a first heat source, a mold, a second heat source, and an imaging device. The hearth is configured to receive a feedstock containing metals. The first heat source is configured to melt the feedstock on the hearth. The mold is configured to be injected with molten raw material. The second heat source is configured to provide thermal energy to the mold and the interior of the mold. The imaging device is connected to the controller and configured to acquire an image of the top surface of the mold as a plurality of data points arranged in a matrix. The controller is configured to detect sticking based on the image. The second heat source is further configured to irradiate the casting with an electron beam.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] One embodiment of the present invention relates to an apparatus, method, and program for producing ingots of metals such as titanium. [Background technology]

[0002] One method for producing a metal ingot is the melting and casting method. In this method, a liquid metal (molten metal) obtained by melting a raw material metal powder, pellets, wires, sponges, briquettes, plates, billets, etc. is poured into a mold and solidified to obtain a metal ingot that reflects the shape of the mold. For example, Patent Document 1 discloses that a titanium ingot having a cylindrical shape can be produced by irradiating a raw material titanium briquette with an electron beam to form a molten metal, and pouring and cooling the molten metal into a cylindrical mold. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-22976 A Summary of the Invention [Problem to be solved by the invention]

[0004] One of the embodiments of the present invention aims to provide a novel apparatus and method for manufacturing a metal ingot, and a program for executing this method. For example, one of the embodiments of the present invention aims to provide an apparatus and method for manufacturing a metal ingot, such as a titanium ingot, with high quality and / or high yield by applying a melting and casting method, and a program for executing this method. [Means for solving the problem]

[0005] One embodiment of the present invention is an apparatus for producing metal ingots. The apparatus includes a melting furnace and a controller. The melting furnace includes a hearth, a first heat source, a mold, a second heat source, and an imaging device. The hearth is configured to receive a feedstock material including a metal. The first heat source is configured to melt the feedstock material on the hearth. The mold is configured to be poured with the molten feedstock. The second heat source is configured to provide thermal energy to the mold and an interior of the mold. The imaging device is connected to the controller and configured to acquire an image of a top surface of the mold as a plurality of data points arranged in a matrix. The controller is configured to detect the presence of a mold based on the image. The second heat source is further configured to irradiate the mold with an electron beam.

[0006] One embodiment of the present invention is a method for manufacturing a metal ingot, the method including melting a raw material containing a metal in a melting furnace to form a molten metal and pouring the molten metal into a mold, acquiring an image of the upper surface of the mold as a plurality of data points arranged in a matrix using an imaging device provided in the melting furnace, detecting any adhesion based on the image using a control device connected to the imaging device, and irradiating the adhesion with an electron beam.

[0007] One embodiment of the present invention is a control program configured to cause a control device connected to an imaging device provided in a melting furnace for producing a metal ingot by pouring molten metal into a mold to execute the following steps: The steps include acquiring an image of the upper surface of the mold as a plurality of data points arranged in a matrix via the imaging device, detecting adhesion based on the image, and, when the adhesion is detected, supplying thermal energy to the adhesion using a heat source provided in the melting furnace.

[0008] One embodiment of the present invention is a computer-readable storage medium on which the above-mentioned control program is recorded. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram of a metal ingot manufacturing apparatus according to an embodiment of the present invention. [Diagram 2] 1 is a schematic end view of an apparatus for producing a metal ingot according to one embodiment of the present invention, and a top view of a portion of the apparatus. [Diagram 3] 1A and 1B are schematic end and top views of a portion of an apparatus for producing a metal ingot according to one embodiment of the present invention. [Figure 4] 1 is a flowchart showing a method for manufacturing a metal ingot according to one embodiment of the present invention. [Diagram 5] 1A and 1B are schematic top views illustrating the occurrence of sticking in a melting and casting method, and schematic end views illustrating a method for producing a metal ingot according to one embodiment of the present invention. [Figure 6] 1 is a schematic diagram illustrating a method for producing a metal ingot according to one embodiment of the present invention. FIG. [Figure 7] 1 is a schematic diagram illustrating a method for producing a metal ingot according to one embodiment of the present invention. FIG. [Figure 8] 1 is a schematic diagram illustrating a method for producing a metal ingot according to one embodiment of the present invention. FIG. [Figure 9] 1 is a schematic diagram illustrating a method for producing a metal ingot according to one embodiment of the present invention. FIG. [Figure 10] 1 is a chart showing the results of an example (A) and a comparative example (B). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, each embodiment of the present invention will be described with reference to the drawings, etc. However, the present invention can be embodied in various forms without departing from the gist of the present invention, and should not be construed as being limited to the description of the embodiments exemplified below.

[0011] In the drawings, the width, thickness, shape, etc. of each part may be shown diagrammatically compared to the actual embodiment in order to make the explanation clearer, but it is merely an example and does not limit the interpretation of the present invention. In this specification and each figure, elements having the same function as those explained with respect to the previous figures may be given the same reference numerals and duplicated explanations may be omitted. When describing a part of an element to which a numeral is given, a lowercase alphabet is added to the numeral. When describing multiple elements having the same or similar structure in a distinguished manner, a hyphen and a natural number are added after the numeral. When describing multiple elements having the same or similar structure collectively, only the numerals are used.

[0012] Here, dissolution is a phenomenon in which gas, liquid, and solid are mixed in a liquid to form a uniform liquid phase, but in the following description, it is used as a term that also includes melting, which is a phenomenon in which a solid changes into a liquid.

[0013] 1. Metal ingot manufacturing equipment First, a manufacturing apparatus 100 according to one embodiment of the present invention will be described. The manufacturing apparatus 100 is an apparatus for manufacturing a metal ingot by a melting casting method, and is configured to heat and melt a raw material containing a metal (a zero-valent metal) by supplying thermal energy, and to inject the molten metal (molten metal) into a mold. The molten metal is cooled in the mold to obtain a metal ingot. The raw material is heated using a heat source. Examples of the heat source include an electron gun and a plasma torch. When the former is used, thermal energy is supplied by an electron beam emitted from an electron gun, and when the latter is used, thermal energy is supplied by an arc discharge emitted from a plasma torch. The former method is called an electron beam melting casting method, and the latter method is called a plasma arc melting casting method. Hereinafter, an electron beam melting casting method using an electron gun as a heat source will be described, but one embodiment of the present invention can also be applied to a plasma arc melting casting method using a plasma torch as a heat source.

[0014] There is no restriction on the metal that can be used in the manufacturing apparatus 100, and raw materials containing various metals such as titanium, copper, nickel, aluminum, zirconium, hafnium, tungsten, molybdenum, tantalum, or alloys containing metals selected from these metals can be handled. There is no restriction on the shape of the raw material, and not only raw materials in the form of powder, pellets, rods, wires, or plates, but also metal scraps that are by-produced when cutting metals and contain raw materials of various shapes may be used as the raw material. The density of the raw material is also arbitrary, and when using a raw material containing titanium, for example, sponge titanium produced by reduction of titanium tetrachloride, as exemplified by the Kroll method or the Hunter method, may be used, and an ingot of a metal containing titanium can be manufactured. Note that the metal containing titanium includes not only simple titanium but also titanium alloys such as titanium-aluminum alloys.

[0015] Fig. 1 is a block diagram of the manufacturing apparatus 100, and Fig. 2(A) is a schematic end view of the manufacturing apparatus 100. As shown in Fig. 1, the manufacturing apparatus 100 includes a melting furnace 110 and a control device 180. The control device 180 is connected to the melting furnace 110 or at least one component (described below) provided in the melting furnace 110 via an application programming interface (not shown), and controls all or part of the functions of the melting furnace 110.

[0016] 1-1. Melting furnace 2(A), the melting furnace 110 has a chamber 112 that provides a space for melting and solidifying the raw material, and the chamber 112 is equipped with a feeder 116 such as a drum feeder filled with the raw material 102 containing metal, and an exhaust device (vacuum pump) 114 for reducing the pressure inside the chamber 112. The exhaust device 114 can create a reduced pressure atmosphere of 0.01 Pa or less inside the chamber 112. This makes it possible to handle highly active metals, such as titanium, which easily reacts with oxygen and nitrogen in a molten state.

[0017] Further provided within the chamber 112 are a hearth 120 functioning as a container for melting metal, a hopper 118 for transporting the raw material 102 supplied from the feeder 116 to the hearth 120, and one or more electron guns 150 functioning as a heat source for supplying thermal energy required to melt the raw material 102 on the hearth 120. The hopper 118 is provided so that the hearth 120 side is lower than the feeder 116 side, and is connected to a vibration device (not shown). Therefore, for example, the feeder 116 can be rotated to supply the raw material 102 to the hopper 118, and the raw material 102 can be transported to the hearth 120 by vibrating the hopper 118.

[0018] The hearth 120 is configured to hold the raw material 102 and the molten metal, and to supply the molten metal to a mold 124 (described later). For this purpose, although not shown, the hearth 120 is provided with a spout for pouring the molten metal 104 into the mold 124, the spout being aligned with the mold 124. Although not shown, the hearth 120 may also receive raw material melted above it. Note that a skull 122 may be formed on the hearth 120 in advance, which is obtained by melting and solidifying the metal contained in the raw material. The skull 122 functions as a flow path for the molten metal 104, but a portion of it may be remelted to function as a supply source for the molten metal 104.

[0019] The electron gun 150 is configured to irradiate the raw material 102 on the hearth 120 with an electron beam (EB). Although not shown, the electron gun 150 basically comprises a filament for generating thermal electrons and a magnet for deflecting the electron beam. The irradiation direction of the electron beam is controlled by controlling the magnetic field of the magnet, and the electron beam can be scanned over the hearth 120. The metal contained in the raw material 102 is melted by the energy supplied by the electron beam, and a molten metal 104 is formed.

[0020] The chamber 112 further includes one or more molds 124 into which the molten metal 104 is poured. The molds 124 are disposed below the spout of the hearth 120. The molds 124 are made of a metal with high thermal conductivity, such as copper. As an optional configuration, the molds 124 may have a flow path 126 for cooling the molds 124. The molten metal 104 poured into the molds 124 can be effectively cooled by circulating a cooling medium through the flow path 126, such as water, glycols such as ethylene glycol and propylene glycol, alcohols such as ethanol and isopropanol, fluorine-containing compounds such as tetradecafluorohexane and perfluoro 2-butyltetrahydrofuran, silicon oil, and aromatic compounds that are solid at room temperature, such as a mixture of biphenyl and diphenyl ether.

[0021] There are no restrictions on the shape of the mold 124. For example, as shown in FIG. 2(B), the shape of the horizontal cross section of the mold 124, more specifically, the shape of the inner wall in the horizontal cross section, may be a polygon such as a rectangle, or as shown in FIG. 2(C), it may be a circle. By using a mold 124 having an inner wall with a rectangular or circular horizontal cross section, a rectangular parallelepiped or cylindrical metal ingot 106 can be obtained, respectively. Although not shown, the horizontal cross section of the inner wall of the mold 124 may be an ellipse, or may be composed of straight lines and curves. There are also no restrictions on the size of the mold 124, and for example, a mold with a horizontal cross section area of ​​1500 cm2 may be used. 2 More than 15000cm 2 The number of templates 124 is not limited. That is, the number of templates 124 may be one, or two or more.

[0022] A dovetail 128 that functions as a bottom lid is provided at the bottom of the mold 124, and a pulling mechanism 130 (described later) is connected to the dovetail 128. A starting block 108, also called a stub, may be formed on the dovetail 128. The starting block 108 contains metal contained in the raw material 102 to be cast, and is formed by pouring molten metal 104 onto the dovetail 128 and then solidifying it.

[0023] The starting block 108 may be connected to a pull-out mechanism 130 directly or via a dovetail 128. The pull-out mechanism 130 may be configured, for example, by a shaft 132, a motor 134 for sliding the shaft 132, and a belt 136 for transmitting the rotational force of the motor 134 to the shaft 132. The configuration of the pull-out mechanism 130 is not limited to this, and for example, a chain or a gear may be used instead of the belt 136. The shaft 132 may be, for example, a rod-shaped gear called a rack, or a shaft screw. The shaft 132 can be slid up and down by rotating the shaft 132 using the rotational force of the motor 134 or by rotating a gear fitted to the shaft 132. The molten metal 104 injected into the mold 124 starts to solidify from the starting block 108 side, so by using a pulling mechanism 130 to pull out the dovetail 128 and / or the starting block 108 from the mold 124 via a shaft 132, the portion of the molten metal 104 that has solidified within the mold 124 can be obtained as a metal ingot 106. Note that the starting block 108 may be integrated with the molten metal 104 when it solidifies, and may constitute a part of the metal ingot 106.

[0024] Optionally, the melting furnace 110 may include a cooling pipe 138 for cooling the metal ingot 106. The cooling pipe 138 is disposed to surround the shaft 132. Like the mold 124, the cooling pipe 138 is preferably made of a metal such as copper that has high thermal conductivity. The cooling pipe 138 may also be provided with a flow passage 140 for circulating a cooling medium.

[0025] The melting furnace 110 is further provided with one or more electron guns 152 that function as a heat source for supplying thermal energy to the mold 124 and the inside of the mold 124. Unlike the electron gun 150, the electron gun 152 is arranged to irradiate the inside of the mold 124 with an electron beam, and therefore can also irradiate the surface of the molten metal 104 with an electron beam. This allows the temperature of the molten metal 104 to be adjusted and the solidification rate to be controlled. Furthermore, the electron gun 152 is configured to also irradiate the mold 124 with an electron beam, and therefore, as described below, can irradiate the electron beam to the mold 124 with the electron beam to melt or evaporate the molded adhesion adhering to the upper surface or inner wall of the mold 124 and remove the molded adhesion. Like the electron gun 150, the electron gun 152 also has a filament and a magnet, and by controlling the magnetic field of the magnet, the electron beam can be scanned over the molten metal 104 and the electron beam can be selectively irradiated to any position.

[0026] 2, the melting furnace 110 further includes an imaging device 160 outside the chamber 112. The imaging device 160 is positioned so as to capture an image of the top surface of the mold 124. Examples of the imaging device 160 include an imaging device including a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) device. By using the imaging device 160, an image of the mold 124 and the molten metal 104 poured therein can be captured.

[0027] 3(A) shows a schematic end view of the imaging device 160 and its vicinity. An opening is provided in the chamber 112, and a window 162 is provided to cover the opening. The window 162 includes one or more of glass, quartz glass, and lead glass, and may be, for example, a laminate of quartz glass and lead glass. The imaging device 160 is positioned so as to be able to capture an image of the top surface of the mold 124 through the window 162.

[0028] The position where the opening is provided can be set arbitrarily. However, when the pressure inside the chamber 112 is reduced to melt the raw material 102, some types of metal may evaporate, resulting in metal deposition on the inner wall of the chamber 112 or inside the window 162. In particular, metal evaporated from the molten metal is likely to deposit at a position that overlaps with the mold 124 in the vertical direction. For this reason, as shown in FIG. 2(A), it is preferable to provide the opening at a position that does not overlap with the mold 124 or hearth 120, and to capture an image of the mold 124 from an oblique direction through the opening.

[0029] In addition, as an optional configuration, an adhesion prevention plate 164 overlapping with the window 162 may be provided in the chamber 112. The adhesion prevention plate 164 is a metal plate having a substantially circular shape. By providing the adhesion prevention plate 164, it is possible to suppress adhesion of metal vapor to the window 162, and as a result, metal deposition is prevented, and the transparency of the window 162 can be maintained. In order to enable the imaging device 160 to capture an image of the mold 124, one or more openings 164a may be provided in the adhesion prevention plate 164, and the adhesion prevention plate 164 may be rotated by a motor (not shown). The shape of the opening 164a may also be arbitrary, and it is sufficient that the opening 164a is formed so that the mold 124 can be captured when the opening 164a and the imaging device 160 overlap. For example, the opening 164a may be circular or rectangular. When a plurality of openings 164a are provided, their arrangement may be arbitrary, and for example, they may be arranged symmetrically with respect to the center of the adhesion prevention plate 164. In addition, a plurality of openings 164a may be arranged at equal intervals along the rotation direction of the adhesion prevention plate 164. Imager 160 is configured to capture an image when aperture 164 a overlaps imager 160 .

[0030] As an optional configuration, together with or instead of the adhesion prevention plate 164, a nozzle 166 for spraying an inert gas such as argon or helium onto the inside of the window 162 may be provided in the chamber 112 (FIG. 2(A)). The nozzle 166 is connected to an inert gas supply source (not shown) provided outside the chamber 112. When the raw material is melted, by supplying an inert gas from the inert gas supply source to the inside of the window 162, adhesion of metal vapor to the window 162 is suppressed, and the transparency of the window 162 is maintained.

[0031] Although not shown, it is possible to introduce an inert gas into the chamber 112. A gas inlet for this purpose may be further provided. An inert gas supply source is also connected to the gas inlet.

[0032] 1-2.Control device The control device 180 is a computer having communication and calculation functions, and may be a notebook or stationary computer, or may be a portable communication terminal such as a tablet computer. The control device 180 is connected to the melting furnace 110 or all or a part of the components provided in the melting furnace 110 (e.g., the electron gun 152 and the imaging device 160) via an external network such as the Internet or an internal network such as a LAN (Local Area Network).

[0033] The control device 180 includes a control unit 182 for controlling the operation of the control device 180, as well as an input unit 184, an output unit 186, a transmission / reception unit 188, a storage unit 190, an audio output unit 192, and the like, all of which are controlled by the control unit 182. The storage unit 190 stores a basic application program for operating the control device 180, as well as a control program for implementing a manufacturing method for a metal ingot, which will be described later. The control unit 182 includes a processor such as a central processing unit (CPU), and controls various processes executed by the control device 180 by operating the basic application program and the above-mentioned control program stored in the storage unit 190. The input unit 184 is a user interface used when inputting commands and information to the control device 180, and typically includes a keyboard, a touch panel, a mouse, or a combination of these. The output unit 186 provides various data stored in the storage unit 190 as images or printed matter, and is an output device such as a display, such as a liquid crystal display or an organic electroluminescent display, or a printer. The transmission / reception unit 188 has a function of communicating with the melting furnace 110 via a network. For example, the transmitter / receiver 188 receives images captured by the imaging device 160 and transmits signals to components provided in the melting furnace 110, such as the electron gun 152. The audio output unit 192 is a speaker capable of generating various sounds.

[0034] 1 shows an example in which all of the exhaust device 114, feeder 116, hopper 118, extraction mechanism 130, electron guns 150 and 152, and image capture device 160 provided in the melting furnace 110 are controlled by the control device 180. However, the control device 180 does not need to control all of these components, and may be configured to control and operate, for example, only the image capture device 160, or the image capture device 160 and the electron gun 152. In this case, the other components, for example, the feeder 116, hopper 118, extraction mechanism 130, and electron gun 150, may be controlled and operated by a control system independent of the control device 180.

[0035] As described in detail below, by using an imaging device 160 for capturing images of the mold 124 and the molten metal 104 poured therein, and an electron gun 152 configured to irradiate the mold 124 and the molten metal 104 with an electron beam, the occurrence of adhesion to the mold 124 can be detected and removed in a timely manner. This makes it possible to prevent deterioration in quality and yield caused by adhesion being mixed into the metal ingot, and makes it possible to manufacture high-quality metal ingots with good yield.

[0036] 2.Metal ingot manufacturing method Hereinafter, there will be described a method for manufacturing a metal ingot using the manufacturing apparatus 100. Fig. 4 is a flow chart showing an example of a method for manufacturing a metal ingot according to an embodiment of the present invention.

[0037] 2-1. Production of molten metal from raw materials First, the atmosphere in the chamber 112 is appropriately adjusted. For example, the exhaust device 114 may be used to reduce the pressure in the chamber 112. When using a source material 102 containing a metal such as titanium that exhibits high reactivity in a molten state, it is preferable to adjust the pressure in the chamber 112 to 0.001 Pa to 0.005 Pa. When using a source material 102 containing a metal that exhibits low reactivity in a molten state, the atmosphere in the chamber 112 may be air.

[0038] Subsequently, the raw material 102 is introduced from the feeder 116 into the hopper 118 (S1). For example, a drum feeder filled with the raw material 102 may be used as the feeder 116, and the drum feeder may be rotated to drop the raw material 102 into the hopper 118. A vibration device (not shown) is provided in the hopper 118, and the raw material 102 moves toward the hearth 120 by vibration of the hopper 118, and is finally supplied into the hearth 120.

[0039] After that, one or more electron guns 150 are used to scan the electron beam over the hearth 120 so that the raw material 102 is irradiated with the electron beam. This melts the metal contained in the raw material 102, forming the molten metal 104 (S2). When a certain amount of the molten metal 104 accumulates, the molten metal 104 flows out of the hearth 120 and is supplied to the mold 124 (S3). The supply speed of the molten metal 104 to the mold 124 can be adjusted by appropriately controlling the supply amount of the raw material 102 and the intensity of the electron beam. Note that a dovetail 128 may be placed in advance at the bottom of the mold 124 before the molten metal 104 is poured into the mold 124. Alternatively, the dovetail 128 and the starting block 108 formed thereon may be placed (see FIG. 2), or only the starting block 108 may be placed separately instead of the dovetail 128. When the starting block 108 is in place, the molten metal 104 will merge with the starting block 108 as it solidifies to form a metal ingot 106 .

[0040] The surface of the molten metal 104 supplied to the mold 124 may also be scanned with the electron beam emitted from the electron gun 152. By appropriately controlling the intensity and scanning speed of the electron beam from the electron gun 152, the solidification rate can be adjusted.

[0041] After the molten metal 104 is poured, the shaft 132 is gradually slid using the withdrawal mechanism 130 to withdraw the dovetail 128 and the starting block 108 formed thereon from the mold 124. The withdrawal speed may be set appropriately within the range of, for example, 0.5 t / h to 4 t / h. In this way, the metal ingot 106 integrated with the starting block 108 can be obtained.

[0042] 2-2. Detection and removal of casts In the melting casting method using a heat source, steam is generated when melting the raw material and maintaining the raw material in a molten state, and therefore, as shown in Fig. 5(A), relatively small metal lumps called cast-in 125 may adhere to the inner wall of the mold 124. It is believed that cast-in 125 may also be formed when a part of the molten metal 104 is blown off by an electron beam irradiated to the molten metal 104 in the mold 124 and adheres to and solidifies on the upper surface or inner wall of the mold 124. When sponge titanium produced by the Kroll process is used as the raw material 102, chlorides such as magnesium chloride are inevitably mixed into the raw material 102 as impurities, and splashes are generated when these chlorides separate from the surface of the molten metal in the mold 124, adhering to the mold 124, making cast-in 125 likely to occur.

[0043] When the cast-in 125 is extremely small or when the cast-in 125 falls into the molten metal 104 and melts completely again, the effect of the cast-in 125 can be ignored. However, since the density of the cast-in 125 is low compared to the metal ingot 106 itself, if the enlarged cast-in 125 is not remelted and is mixed into the metal ingot 106, defects may occur in the metal ingot 106 or the metal material such as the rolled material obtained by processing the metal ingot 106. It may also cause defects on the surface of the metal ingot 106 or the metal material. Furthermore, if the electron beam is blocked by the cast-in 125, the electron beam cannot be sufficiently irradiated to the molten metal in the mold 124, and the solidification speed becomes uneven. In fact, the inclusion of the cast-in 125 is often not judged by observing the surface of the metal ingot 106, and may be detected only after rolling. Therefore, suppressing the occurrence of the cast-in 125 during melting and casting is the key to improving quality.

[0044] In a method for manufacturing a metal ingot according to one embodiment of the present invention, the manufacturing apparatus 100 is used to detect the inclusion 125 and remove it promptly or at the appropriate time. This prevents the inclusion from remaining in the metal ingot, and allows a high-quality metal ingot to be manufactured with a high yield. This method will be described in detail below.

[0045] (1) Imaging of the mold and molten metal After the supply of the molten metal 104 to the mold 124 is started, the imaging device 160 is operated via the control device 180 described above to obtain an image of the mold 124 and the molten metal 104 supplied thereto (S4). Image information is obtained as gradation data of each of the data points arranged in a matrix shape consisting of multiple columns and multiple rows. Each data point is expressed as a gradation selected from a total of 256 gradations from gradation 0 to gradation 255. When this image is displayed on a display device, each data point corresponds to a pixel, and the gradation is expressed as brightness. In other words, the image of the mold 124 and the molten metal 104 are viewed on the display device as a collection of pixels that provide 256 different levels of brightness. The obtained image information is permanently or temporarily stored in the memory unit 190 via the transmission / reception unit 188 of the control device 180.

[0046] If each data point contains color information, i.e., information on a color selected from red, green, or blue, the color information may be ignored and only the gradation of each data point may be used as gradation data. Alternatively, three data points containing consecutive red, green, and blue color information may be recognized as one data point, and the maximum gradation, minimum gradation, or average gradation of these may be used as gradation data.

[0047] (2) Pretreatment As an optional configuration, the obtained image information may be pre-processed (S5). As described later, the presence or absence of the mold-attached portion 125 is judged and its size is calculated based on the image information, and the accuracy of these calculations can be improved by performing pre-processing. There are no particular restrictions on the image pre-processing, but examples of the pre-processing include processing for removing noise and increasing contrast.

[0048] Examples of pre-processing for noise removal include median filtering, average filtering, weighted average filtering (Gaussian filtering), and spatial filtering. For example, in median filtering, nine data points of 3×3 are processed as one processing target, and the gradation of the central data point is replaced with the median value of the nine data points in the processing target. In the manufacturing method according to one embodiment of the present invention, in addition to the above-mentioned processing, one or more noise removal processes using other known algorithms can be applied.

[0049] The process for increasing contrast can also be performed by appropriately applying a known algorithm. For example, there are processes such as gray-scale conversion by linear conversion, gray-scale conversion by nonlinear conversion using a tone curve such as a quadratic curve, a logarithmic function, or a power function, histogram equalization, windowing, etc. In addition to the above processes, a manufacturing method according to one embodiment of the present invention can apply one or more contrast-increasing processes using other known algorithms.

[0050] (3) Creating a reference line In a manufacturing method according to one embodiment of the present invention, the determination of the presence or absence of the molded part 125 and the calculation of its size are performed by creating a reference line (S6). The details of this will be described below.

[0051] (3-1) In the case of a rectangular mold FIG. 6(A) shows an example of an image acquired by the imaging device 160 and a partially enlarged view of the image. First, an evaluation area is selected from the entire image. Since the adhesion 125 is likely to occur on the inner wall of the mold 124, in the case of the mold 124 having an inner wall with a rectangular horizontal cross section, one side wall and the molten metal 104 in its vicinity may be set as the evaluation area R. More specifically, one side wall and a range from the side wall to a distance D toward the inside of the mold 124 may be set as the evaluation area R. The distance D may be set appropriately depending on the size of the mold 124 and the quality required for the metal ingot 106, and may be appropriately selected from a range of, for example, more than 30 mm and less than or equal to 100 mm. As will be described later, the occurrence of the adhesion 125 is judged using information obtained from the evaluation area R, so the distance D is preferably determined taking into consideration the size of the adhesion 125 to be generated. For example, the distance D may be set to a threshold distance d th The evaluation area R may be 2 to 10 times, or 3 to 5 times (described later). Although only one evaluation area R is shown in Fig. 6(A), there may be multiple evaluation areas R. For example, a side wall facing a side wall included in one evaluation area R and the molten metal 104 in the vicinity thereof may also be used as the evaluation area. The side wall may be a side wall along the longitudinal direction of the mold 124, or a side wall perpendicular to the longitudinal direction.

[0052] Next, the evaluation region R is divided into n subregions B, i.e., the first subregion B1 to the nth subregion B n The number n can be selected from natural numbers greater than 1, but it is preferable to divide the evaluation region R so that the length of the sidewall included in one sub-region B is greater than 0 mm and less than or equal to 10 mm. Considering the size of the metal ingot to be produced and the accuracy of the reference line, which will be described later, it is preferable that n is 200 or more. The upper limit of n may be, for example, 1500, 1300, or 1100. The first sub-region B1 to the nth sub-region B nare arranged in this order, and as shown in FIG. 6(A), each sub-region B includes a plurality of data points 170. In each sub-region B, the data points 170 are arranged in a plurality of columns parallel to the arrangement direction of the sub-region B (the direction of the dotted arrow in FIG. 6(A)), and the data points 170 have one or more rows. The number of data points 170 included in each row is arbitrary and may be determined according to the distance D and the resolution of the image. In the example shown in FIG. 6(A), each sub-region B includes a plurality of data points 170 arranged in a matrix of 4 rows and 9 columns. Therefore, among the plurality of data points 170 included in each row of each sub-region B, some correspond to the molten metal 104, and some correspond to the side wall of the mold 124. In FIG. 6(A), m is a variable selected from natural numbers of 1 to (n-2). However, when n is 2, m is 1, and the third sub-region B3 does not exist.

[0053] 6(A), the molten metal 104 is brighter than the mold 124, and is therefore represented by a high-gradation data point 170-1. On the other hand, the mold 124 is represented by a low-gradation data point 170-2. Therefore, the difference in gradation between the data points 170-1 and 170-2 is large, and the boundary between the molten metal 104 and the mold 124 can be clearly identified.

[0054] Next, the first sub-region B1 to the n-th sub-region B n In each of the sub-regions, a critical data point CP is determined. Specifically, as shown in FIG. 6B, one row of data points 170 is selected in each sub-region B. When the number of rows of data points included in each sub-region B is multiple, the same row may be selected in all sub-regions B. Alternatively, multiple rows in each sub-region B may be convergently transformed into one row. In this case, in each sub-region B, the average value of data points 170 located in the column including the data point 170 may be adopted as the gradation of each data point 170. In the example shown in FIG. 6B, there are j rows including 17 data points 170 in each sub-region B, and the data point 170 located in the second row is selected. Here, j is a natural number equal to or greater than 2.

[0055] Next, in the selected (or convergent transformed) row, data points 170 on the molten metal 104 side (inside the mold 124) are selected one by one, and the gradation of the selected data point 170 is compared with that of a data point 170 adjacent to the side wall side of the mold 124, and the gradation difference ΔG is calculated. The data point 170 whose absolute value of the gradation difference ΔG first exceeds a certain value (threshold gradation) is determined as the critical data point CP. By performing this operation in each sub-region B, multiple critical data points CP, the same number as the number of sub-regions B, are obtained.

[0056] The threshold for determining the critical data point CP can be set arbitrarily. When the data points 170 have a gradation of 256, the threshold gradation may be selected, for example, from the range of 50 to 255, 100 to 255, or 150 to 255. Alternatively, the maximum gradation difference ΔG among the gradation differences ΔG of all combinations of adjacent data points 170 in the selected (or convergent transformed) row of each sub-region B may be set as the threshold gradation. max The threshold gradation may be a predetermined percentage of the absolute value of the threshold gradation. The predetermined percentage may be selected from the range of 50% to 100%, and may be, for example, 70%.

[0057] The method of determining the critical data point CP is not limited to this. For example, the pair of data points in the selected (or convergent transformed) row where the above grayscale difference is the largest (i.e., the above maximum grayscale difference ΔG maxAlternatively, one of the data points (pair of data points giving a gradation) may be determined as the critical data point CP. For example, in the example shown in FIG. 6(B), a plurality of data points 170-1 having high gradation are continuous on the molten metal 104 side. On the other hand, a plurality of data points 170-2 having low gradation are continuous on the side wall side of the mold 124. Therefore, the gradation difference ΔG between the data point 170-1a closest to the side wall among the data points 170-1 and the data point 170-2a closest to the molten metal 104 among the data points 170-2 is larger than the gradation difference ΔG between any other pair of adjacent data points. Therefore, the data point 170-1a or the data point 170-2a is determined as the critical data point CP. Note that selecting the data point 170-2a in this manner reduces the maximum gradation difference ΔG described above. max This corresponds to when a certain percentage of the absolute value of is set to 100%.

[0058] Next, an approximation line for the multiple critical data points CP is created as a reference line. Any algorithm may be used to create the approximation line, for example, the least squares method. The approximation line may be a linear line or a curve of an order other than linear. Alternatively, the approximation line may be composed of a straight line and a curve. When no casting 125 occurs, the critical data points CP are data points corresponding to the boundary between the molten metal 104 and the mold 124, and by connecting the critical data points CP, a straight line that approximately overlaps with the inner wall is obtained. Therefore, the reference line 172 substantially overlaps with the inner wall. However, as shown in FIG. 7, when the casting 125 occurs on the inner wall, connecting the multiple critical data points CP gives a curve that protrudes from the mold 124 into the molten metal 104. Therefore, the reference line 172 does not completely overlap with the inner wall, but is a straight line, a curve, or a combination thereof that is at least partially separated from the side wall. In the manufacturing method according to the embodiment of the present invention, by detecting a critical data point CP located on the molten metal side from the reference line 172, it is possible to determine that the molded-in part 125 has occurred at a position corresponding to the critical data point CP. Therefore, the occurrence of the molded-in part 125 can be easily detected and its position can be identified.

[0059] If it is determined that the adhesion 125 has occurred in all cases where the critical data point CP is detected on the molten metal side from the reference line 172, even small adhesions 125 that do not affect the properties of the metal ingot 106 will be detected. Therefore, the distance d of each critical data point CP from the reference line 172 may be calculated (see FIG. 7) and the occurrence of adhesions 125 to be removed may be determined using the distance d. The distance d may be centered on the reference line 172, with the molten metal 104 side being positive and the mold 124 side being negative. Since the distance d depends on the size of the adhesion 125, the size of the adhesion 125 can be estimated by calculating the distance d. This makes it possible to determine the occurrence of adhesions 125 to be removed, and also to determine the priority order of adhesions 125 to be removed. For example, when the distance d is a predetermined value, i.e., a threshold distance d th If the distance exceeds the threshold distance d, it is determined that the adhesion 125 has occurred. th The threshold distance d may be appropriately determined depending on the size of the mold 124 and the quality required for the metal ingot 106, and may be selected, for example, from the range of 2 mm to 30 mm. th is preferably set to a size that is a size of the casting 125 that needs to be irradiated with the electron beam and that can be dissolved in the molten metal 104 even if it is dropped into the molten metal 104, for example.

[0060] Distance d is the threshold distance d th If it is less than 1 minute, that is, if it is determined that the formation of the mold-attached 125 is not significant, the processes from S4 to S6 are repeated again. The time until the process of S4 is started again after the process of S4 is started may be set arbitrarily, and may be selected from the range of, for example, 0.01 seconds to 1 minute, 0.01 seconds to 10 seconds, or 0.01 seconds to 1 second.

[0061] As described above, during the manufacture of the metal ingot 106, the electron gun 152 irradiates the molten metal 104 with an electron beam continuously or intermittently. Therefore, depending on the timing of the electron beam irradiation and the timing of the image capture, the obtained image may be distorted due to halation or the like. In this case, the critical data point CP cannot be determined accurately, and the reference line 172 and the distance d cannot be accurately created or calculated. Therefore, in order to eliminate the influence of image distortion, the series of processing steps from S4 to S6 are repeated multiple times (e.g., k times, where k is a natural number equal to or greater than 1) until the distance d is equal to or smaller than the threshold distance d in each of the multiple consecutive processing steps (e.g., (k+1) times). th If the number of times exceeds the number of times, it may be determined that the mold 125 has formed. k may be appropriately selected from the range of 5 to 30. When one operation is repeated k times, the operation is performed (k+1) times.

[0062] (3-1) In the case of a circular mold Even when the horizontal cross section of the inner wall of the mold 124 is a circle, it is possible to create the reference line 172 to detect the mold-sticking 125 and calculate its size. Specifically, first, the side wall of the mold 124 and the molten metal 104 in its vicinity are set as the evaluation region R (see FIG. 8(A)). More specifically, the side wall and the range from the side wall to the center of the circle up to a distance D can be set as the evaluation region R. Therefore, the evaluation region R is a region sandwiched between two concentric circles with different radii. The distance D can be set appropriately depending on the size of the mold 124 and the quality required for the metal ingot 106, and can be appropriately selected from a range of more than 30 mm and not more than 100 mm, for example.

[0063] Next, set a number of straight lines Ln extending radially from the center of the circle of the horizontal cross section of the mold 124. It is preferable that the multiple straight lines Ln are set so that the angle θ between adjacent straight lines is the same, that is, so that they extend radially at equal angles.

[0064] Next, a critical data point CP is determined for each straight line Ln. Specifically, as shown in FIG. 8(B), a plurality of data points 170 that overlap with the straight line Ln and are included in the evaluation region R are selected as evaluation target data points 170-3 (data points hatched in FIG. 8(B)). Then, a critical data point CP is determined from the evaluation target data points 170-3. That is, one by one of the data points on the molten metal 104 side (the inside side of the mold 124) is selected from the evaluation target data points 170-3, and the gradation of the selected data point is compared with that of a data point 170 adjacent to the side wall side of the mold 124, and the difference is calculated. The data point 170 whose difference first exceeds the threshold gradation is adopted as the critical data point CP. Alternatively, one of the pair of data points with the largest gradation difference may be determined as the critical data point CP. By performing this operation on the data points 170 that overlap with each straight line Ln, the same number of critical data points CP as the straight line Ln are obtained.

[0065] Next, an approximation circle for the multiple critical data points CP is created as a reference line 172. This approximation circle is created so as to be concentric with the inner wall in the horizontal cross section. For example, an approximation circle may be created for all critical data points CP by appropriately using an algorithm such as the least squares method. When no casting 125 occurs, the critical data points CP are data points corresponding to the boundary between the molten metal 104 and the side wall, and by connecting the critical data points CP, a circle that approximately overlaps with the inner wall is obtained. Therefore, the reference line 172 is also a circle that substantially overlaps with the inner wall. However, as shown in FIG. 9, when casting 125 occurs, connecting the multiple critical data points CP gives a curve that protrudes from the mold 124 into the molten metal 104. Therefore, the reference line 172 does not overlap with the inner wall, and is a circle away from the side wall. In the manufacturing method according to the embodiment of the present invention, by detecting a critical data point CP located on the molten metal side from the reference line 172, it is possible to determine that casting 125 has occurred at a position corresponding to this critical data point CP. Therefore, the occurrence of the adhesion 125 can be easily detected and its location can be easily identified.

[0066] As in the case of using a mold 124 having an inner wall with a rectangular horizontal cross section, the occurrence of the sticking 125 may be judged based on the distance from the reference line 172 to each critical data point CP, i.e., the distance d from the reference line 172 to the critical data point CP in the radial direction of the inner wall in the horizontal cross section. This distance d may also be centered on the reference line 172, with the molten metal 104 side being positive and the mold 124 side being negative. Since the distance d depends on the size of the sticking 125, by calculating the distance d, it is possible to detect the occurrence of the sticking 125 that should be removed and to estimate the size of the sticking 125. Furthermore, it is possible to determine the priority order for removing the sticking 125. For example, if the distance d is a threshold distance d th If the distance exceeds the threshold distance d, it is determined that the adhesion 125 that needs to be removed has occurred. th The threshold distance d may be selected from the range of 2 mm to 30 mm, for example. th is preferably set to a size that is a size of the casting 125 that needs to be irradiated with the electron beam and that can be dissolved in the molten metal 104 even if it is dropped into the molten metal 104, for example.

[0067] Regardless of the shape of the mold 124, in any configuration, the distance d is a threshold distance d th If the distance d exceeds the threshold distance d in the series of processing steps from S4 to S6, the control device 180 may be configured to generate a sound (warning sound) using the audio output unit 192. th Alternatively, the controller 180 may be configured to sound an alarm whenever the distance d exceeds the threshold distance d for all of a number of successive processing steps. th The controller 180 may be configured to sound an alarm if the distance d exceeds a threshold distance d. th The controller 180 may be configured to silence the warning sound if the following values ​​are regained:

[0068] Optionally, the image is displayed on the display of the output unit 186, and the distance d is a threshold distance d thThe control device 180 may be configured to indicate on a display the location of the adhesion 125 when the distance d exceeds a threshold distance d. th An arrow indicating the critical data point CP that exceeds the threshold distance d or a figure surrounding the critical data point CP may be displayed on the display. Alternatively, the critical data point CP that is the furthest from the reference line 172 toward the molten metal 104 may be selected, and a circle centered on the selected point may be displayed on the display. Similarly, when the distance d is greater than the threshold distance d th The controller 180 may be configured to stop displaying the circles and arrows when the following values ​​are regained:

[0069] (4) Removal of cast-in deposits Distance d is the threshold distance d th When it is determined that the casting 125 to be removed has been formed by exceeding the size, the electron gun 152 is used to irradiate the casting 125 with an electron beam, for example, to melt and / or evaporate the casting 125 (S7). This makes it possible to selectively irradiate the electron beam on the casting 125 that has grown to a certain size and that may cause a deterioration in the quality of the metal ingot if it grows further (see FIG. 5(B)). That is, the casting 125 that is negligibly small is excluded from the target of the electron beam irradiation, simplifying the work, and the casting 125 can be removed before it becomes excessively large. However, the casting 125 may not melt or evaporate due to the irradiation of the electron beam and may fall into the molten metal 104. In this case, in order to prevent the cast 125 that has fallen from remaining in the metal ingot 106 without melting, it is preferable to irradiate the electron beam on the casting 125 at a stage where it can be melted in the molten metal 104. Regarding the irradiation of the electron beam to the casting 125, specifically, the distance d is set to a threshold distance d via the control unit 182. thThe coordinates of the critical data point CP exceeding the critical value CP are obtained, and the electron gun 152 is controlled and operated so as to irradiate the electron beam with the position corresponding to these coordinates as the center. This operation may be performed automatically by the control device 180, or the coordinates to be irradiated may be specified using the input unit 184, and the electron gun 152 may be operated so as to irradiate the electron beam with the position corresponding to these coordinates as the center. Note that a plurality of electron guns 152 may be provided in the chamber 112, and some of these may be used to irradiate the molten metal 104 with the electron beam continuously or intermittently, and the other may be used to irradiate the cast metal 125 with the electron beam.

[0070] The above-mentioned series of process steps including S4 to S7 are repeated until the melting and casting is completed. In this manufacturing method, the interval between process steps is short compared to the speed at which the metal ingot 106 is drawn out, so that the inclusion of the casting 125 can be prevented throughout the obtained metal ingot 106. As a result, a high-quality metal ingot can be manufactured.

[0071] 3. Control Program A manufacturing method according to one embodiment of the present invention can be implemented by the above-described manufacturing apparatus 100 and a control program installed in its control device 180. Thus, one embodiment of the present invention is a control program for causing the control device 180 to execute some or all of the above-described steps S1 to S7 for manufacturing a metal ingot by a melting and casting method.

[0072] A computer-readable recording medium on which the control program is recorded is also one of the embodiments of the present invention. Examples of the computer-readable recording medium include a magnetic medium such as a hard disk, a flexible disk, and a magnetic tape, an optical medium such as a CD-ROM or a DVD, a magneto-optical medium such as a floptical disk, and a hardware device configured to store and execute the control program, such as a ROM, a RAM, a flash memory, etc. The control program includes not only a machine code such as that generated by a compiler, but also a high-level language code executed by a server using an interpreter, etc. The control program is installed in the storage unit 190 from the computer-readable medium. The control program may be downloadable from a network to the storage unit 190. EXAMPLES

[0073] In this example, the results of experimentally producing a titanium ingot using a production method according to one embodiment of the present invention will be described.

[0074] In this embodiment, a manufacturing apparatus 100 including a melting furnace 110 having a configuration as shown in FIG. 2 was used. Metal pieces including titanium sponge were continuously supplied to the hearth 120 from the feeder 116 via the hopper 118 at a rate of about 3 t / h. After that, an electron gun 150 (manufactured by Ardennes, model EH-800V) for irradiating the molten metal was used to irradiate the hearth 120 with an electron beam. The supply of the obtained molten metal 104 to the two molds 124 (the horizontal cross section of the inner wall is 1360 mm long x 250 mm wide) was started, and the electron gun 152 (manufactured by Ardennes, model EH-800V) arranged above the molds was used to start irradiating the molten metal 104 with an electron beam. Furthermore, the dovetail 128 was lowered at a rate of about 1.5 t / h using the pulling mechanism 130.

[0075] During the above operation, a series of process steps from S4 to S7 described above were repeatedly carried out using the control device 180. Images were acquired through the window 162 using a CMOS camera (manufactured by Keyence Corporation, model CA-H500C) as the imaging device 160 while rotating the adhesion prevention plate 164. Of the acquired images, the side wall in the longitudinal direction and the molten metal 104 in its vicinity, and the side wall opposite to the side wall and the molten metal 104 in its vicinity were each set as evaluation regions R. The setting conditions of the control program are as follows: Processing interval: 0.1 seconds Distance D in evaluation area R (see Figure 6(A)): 50 mm Noise reduction: Median processing Contrast Enhancement: Contrast expansion processing Number of sub-areas B: 860 Number of rows of 170 data points in each sub-area B: 1 Threshold distance d th :12mm Number of consecutive processing steps to determine the occurrence of 125-casting: 10

[0076] The critical data point was determined as follows: The maximum gray level difference ΔG among all combinations of adjacent data points 170 in sub-area B max The maximum gradation difference ΔG from the molten metal side in sub-area B is obtained. max The ratio of the gradation difference ΔG to the maximum gradation difference ΔG max The data point that first shows a gradation difference ΔG exceeding 70% was defined as the critical data point CP.

[0077] The control program installed in the control device 180 determines whether the distance d from the critical data point CP to the reference line 172 is equal to or smaller than the threshold distance d in any of the total of 10 consecutive processing steps. thWhen the distance d exceeds the threshold distance d, the control program determines that a casting 125 that should be removed has occurred, and causes the audio output unit 192 to output a warning sound, and also causes the display of the output unit 186 to display a circle centered on the critical data point CP that is the furthest from the reference line 172 toward the molten metal 104 side. th I have it set to stop warning when the temperature drops below this level.

[0078] When it was determined that the adhesion 125 had occurred, the input unit 184 was used to specify the coordinates of the critical data point CP corresponding to the adhesion 125, and the electron gun 152 was used to irradiate the position corresponding to the coordinates with the electron beam. The irradiation of the electron beam was continued until the warning sound was stopped, that is, until the distance d reached the threshold distance d. th The following was done until recovery.

[0079] As a comparative example, the occurrence of the adhesion 125 was judged by visual inspection, and the adhesion 125 was removed by using the electron gun 152. Specifically, the sound output unit 192 was not made to output a warning sound, and the distance d was a threshold distance d th The control program was changed so that no display was given on the display even if the time exceeded 100 s, and the same operation as in the example was performed.

[0080] The results of the example and the comparative example are shown in FIG. 10(A) and FIG. 10(B), respectively. In both charts, the horizontal axis is the time (seconds) from the start of melting the raw material, and the time from the start of melting to the end of melting in the example and the comparative example was about 2 hours 20 minutes and 2 hours, respectively. The vertical axis is the distance d (unit: mm) from the side wall of the mold 124 to the critical data point CP, which corresponds to the size of the molded part 125. As shown in the chart of FIG. 10(A), it can be seen that the distance d is small and its fluctuation can be significantly suppressed by using the manufacturing method according to the embodiment of the present invention. Specifically, the distance d is a maximum of 18 mm from the start of melting to the end, and can be suppressed to 20 mm or less. This suggests that the manufacturing method can detect the molded part 125 before it grows large, even if it occurs, and can quickly remove the molded part 125. On the other hand, as can be seen from the chart of FIG. 10(B), it can be seen that the distance d fluctuates greatly when operated by visual inspection, reaching a maximum of nearly 30 mm. This suggests that the detection of the adhesion 125 is delayed when the adhesion is performed visually, and as a result, it is difficult to remove the adhesion 125 in a timely manner before it grows larger.

[0081] The above results indicate that the application of the manufacturing apparatus and manufacturing method according to one embodiment of the present invention can significantly reduce the probability of the inclusion of the casting 125 in the metal ingot 106. This effect contributes to the manufacture of high-quality metal ingots 106 with a high yield. It is possible to handle metal ingots longer than those manufactured in the examples without any problems.

[0082] Based on the above-mentioned embodiments of the present invention, those in which a person skilled in the art appropriately adds, removes, or modifies components, or adds, omits, or modifies processes are also included in the scope of the present invention as long as they include the gist of the present invention. Even if there are other effects and advantages different from those provided by the aspects of the above-mentioned embodiments, those that are clear from the description in this specification or that can be easily predicted by a person skilled in the art are naturally considered to be provided by the present invention. [Explanation of symbols]

[0083] 100: manufacturing equipment, 102: raw material, 104: molten metal, 106: metal ingot, 108: starting block, 110: melting furnace, 112: chamber, 114: exhaust device, 116: feeder, 118: hopper, 120: hearth, 122: skull, 124: mold, 125: casting, 126: flow path, 128: dovetail, 130: extraction mechanism, 132: shaft, 134: motor, 136: belt, 138: cooling pipe, 140: flow path, 150 : electron gun, 152: electron gun, 160: imaging device, 162: window, 164: shield, 164a: opening, 170: data point, 170-1: data point, 170-1a: data point, 170-2: data point, 170-2a: data point, 170-3: data point to be evaluated, 172: reference line, 180: control device, 182: control unit, 184: input unit, 186: output unit, 188: transmission / reception unit, 190: storage unit, 192: audio output unit

Claims

1. A melting furnace and a control device are included. The melting furnace is a hearth for receiving the metal-bearing feedstock; a first heat source for melting the raw materials on the hearth; a mold into which the molten material is poured; a second heat source configured to provide thermal energy to the mold and an interior of the mold; and an imaging device coupled to the controller and configured to capture an image of the top surface of the mold as a plurality of data points arranged in a matrix; The control device is configured to detect casting based on the image; The apparatus for producing a metal ingot, wherein the second heat source is further configured to provide thermal energy to the casting.

2. The control device includes: selecting an evaluation area from the image that includes at least a portion of the mold and a portion of an interior of the mold; Dividing the evaluation region into first through nth subregions, each subregion including at least one row including a plurality of the data points; determining critical data points in each of the first through nth subregions; creating an approximation line for the critical data points of the first through nth subregions; and calculating a distance from the approximation line to the critical data point in a direction perpendicular to a side wall of the mold; The method is configured to carry out a process including the steps of: n is a natural number greater than 1, 2. The apparatus of claim 1, wherein in each of the first through nth subregions, the critical data point is a data point at which the difference in gradation between adjacent data points first exceeds a threshold gradation when the plurality of data points included in the row are selected from the interior side of the mold.

3. The apparatus of claim 2 , wherein the controller is configured to determine that the gluing has occurred if, after the step, the distance exceeds a threshold distance.

4. The control device includes: Repeating the steps k times; and The method is configured to determine that the adhesion has occurred when the distance exceeds a threshold distance in any of the (k+1) consecutive steps, The apparatus of claim 2 , wherein k is a natural number equal to or greater than 1.

5. Melting raw materials containing metal in a melting furnace to form a molten metal and pouring the molten metal into a mold; acquiring an image of the top surface of the mold using an imaging device installed in the melting furnace as a plurality of data points arranged in a matrix; detecting the adhesion based on the image by a control device connected to the imaging device; and irradiating the casting with an electron beam.

6. selecting an evaluation area from the image that includes at least a portion of the mold and a portion of an interior of the mold; Dividing the evaluation region into first through nth subregions, each subregion including at least one row including a plurality of the data points; determining critical data points in each of the first through nth subregions; creating an approximation line for the critical data points of the first through nth subregions; and calculating a distance from the approximation line to the critical data point in a direction perpendicular to a side wall of the mold; n is a natural number greater than 1, The manufacturing method described in claim 5, wherein in each of the first to nth sub-regions, the critical data point is a data point at which the difference in gradation between adjacent data points first exceeds a threshold gradation when the multiple data points included in the row are selected from the internal side of the mold.

7. The method of claim 6 further comprising determining that the gluing has occurred if the distance exceeds a threshold distance.

8. repeating a series of steps including the acquisition of the image and the calculation of the distance k times; and determining that a mold has formed if the distance exceeds a threshold distance in any of the (k+1) consecutive times of the steps; The method according to claim 6 , wherein k is a natural number of 1 or more.

9. The method of claim 7 or 8, wherein the irradiation of the electron beam to the mold occurs when the distance exceeds the threshold distance.

10. A control device connected to an imaging device provided in a melting furnace for producing a metal ingot by pouring molten metal into a mold, acquiring an image of the top surface of the mold via the imaging device as a plurality of data points arranged in a matrix; detecting the adhesion based on the image; and When the adhesion is detected, heat energy is supplied to the adhesion using a heat source provided in the melting furnace. A program for executing a process including the steps of:

11. The process further comprises: selecting an evaluation area from the image that includes at least a portion of the mold and a portion of an interior of the mold; Dividing the evaluation region into first through nth subregions, each subregion including at least one row including a plurality of the data points; determining critical data points in each of the first through nth subregions; creating an approximation line for a plurality of the critical data points of the first through nth sub-regions; and calculating a distance from the approximation line to the critical data point in a direction perpendicular to a side wall of the mold; n is a natural number greater than 1, The program of claim 10, wherein in each of the first to nth subregions, the critical data point is a data point selected from a plurality of data points included in the row from the interior side of the mold, the data point being the data point at which the gradation difference between adjacent data points first exceeds a threshold gradation.

12. The program according to claim 11 , further causing the control device to execute, after the step, determining that a mold-sticking has occurred if the distance exceeds a threshold distance.

13. Repeating said steps k times; and The program according to claim 11, further causing the control device to determine that a mold has formed if the distance exceeds a threshold distance in any of (k+1) consecutive times of the steps.

Images