JP2020089895A - Method and system for molding - Google Patents

Abstract

To provide a method for molding capable of suitably cooling a metal material within a mold.SOLUTION: A method for molding comprises a mold preparation step that a mold 13 prepared therein includes a lower half 15 consisting of a sand mold, an upper half 17 consisting of a sand mold and one or more cores 19 consisting of sand molds, in which the one or more cores 19 have a plurality of holes 31 for venting gases, a pouring step that a metal material in a molten state is poured in the mold 13, and a coolant supply step that a liquid coolant is supplied in the plurality of holes 31 of the mold 13 holding the metal material, in which a coolant supply step the supply amount of the coolant is controlled separately between at least one of the plurality of holes 31 and another, at least one thereof.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to a casting method and a casting system.

In a casting (gravity casting) method in which a molten metal material (molten metal) is poured into a mold, there is known a technique of positively cooling the metal material poured into the mold (for example, Patent Documents 1 to 3). Patent Document 1 discloses a technique of supplying air or a mixed air flow of air and water to a flow path provided in a mold. Patent Document 2 discloses a technique of infiltrating water into sand constituting a mold. Patent Document 3 discloses a technique for supplying water to a gas vent hole formed in a core.

Japanese Patent Publication No. 4-45264 JP-A-9-225621 JP, 2011-56559, A

In Patent Documents 1 to 3, for example, a problem in casting a large-sized casting (for example, 50 t or more) and/or a relatively long casting (for example, a bed of a machine tool) is not examined. Then, in the case of casting a large and/or long casting, if the metal material in the mold is positively cooled, for example, a crack may occur in part. Therefore, it is awaited to provide a casting method and a casting system capable of suitably cooling the metallic material in the mold.

A casting method according to an aspect of the present disclosure includes a lower mold made of a sand mold, an upper mold made of a sand mold, and one or more cores made of the sand mold, and the one or more cores are degassed. Mold preparing step for preparing a mold in which a plurality of holes are formed, a pouring step of pouring a molten metal material into the mold, and the plurality of holes of the mold holding the metal material A coolant supply step of supplying a liquid coolant, and in the coolant supply step, the supply amount of the coolant is controlled separately for at least one of the plurality of holes and at least one of the other holes. To do.

In one example, the casting method further has a temperature detection step of detecting the temperature of a plurality of positions of the mold, in the coolant supply step, the temperature of the plurality of positions detected by the temperature detection step. The supply amount of the coolant to the plurality of holes is controlled based on the above.

In one example, in the plan view, the length of a casting part, which is a space for forming a casting made of the metal material, is twice or more the width of the casting part, and the plurality of holes are the casting part. Of the plurality of holes, the holes of which positions are different from each other in the longitudinal direction are separately controlled in the coolant supply step.

In one example, the coolant supply step is started when the temperature of the metal material drops to a temperature lower than the A1 transformation temperature.

In one example, the metallic material is flake graphite cast iron, and the coolant supply step is started when the temperature of the metallic material drops to a temperature of 500° C. or lower.

A casting system according to an aspect of the present disclosure includes a lower mold made of a sand mold, an upper mold made of a sand mold, and one or more cores made of the sand mold, and the one or more cores are degassed. And a cooling device capable of supplying a liquid coolant to the plurality of holes, wherein the cooling device has a plurality of supply amounts of the coolant. At least one of the holes and at least one of the other holes are separately controllable.

According to the above procedure or configuration, the metallic material in the mold can be cooled appropriately.

The schematic perspective view which shows the example of the casting which concerns on embodiment. The typical sectional view showing the composition of the casting system concerning an embodiment. The typical top view which shows the structure of the casting system of FIG. The flowchart which shows the outline of the procedure of the casting method which concerns on embodiment. The figure which shows the time-dependent change of the temperature of the metallic material in the mold which concerns on embodiment.

Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. The following drawings are schematic. Therefore, details may be omitted, and dimensional ratios and the like do not always match the actual ones. In addition, the dimensional ratios of the drawings are not necessarily the same.

In addition, a Cartesian coordinate system xyz is attached to each drawing for convenience of description. The +z side is, for example, the upper side during casting. In the description of the embodiments, the plan view means the view in the z direction unless otherwise specified. After casting, the casting may be utilized with either direction facing up. However, for convenience of description, the term "upper surface" or "lower surface" is also used for the casting with the +z side as the upper side.

(Example of casting)
FIG. 1 is a perspective view showing an example of a casting 1 produced by the casting method according to the embodiment.

The shape and size of the casting 1 may, of course, be appropriately set depending on the application of the casting 1. In the description of this embodiment, the casting 1 having a relatively long shape is taken as an example. An example of such a casting 1 is a bed of a machine tool.

In the long shape referred to here, for example, the length of the casting 1 in the longitudinal direction (x direction) is 1.5 times or more, 2 times or more, 3 times or more of the width (y direction) and the thickness (z direction) or It may be five times or more. The casting 1 may be relatively large. For example, the length of the casting 1 in the longitudinal direction may be 1 m or more, 5 m or more, or 10 m or more. Further, for example, the weight of the casting 1 may be 1 t or more, 5 t or more, 10 t or more, 20 t or more, or 50 t or more.

As will be understood from the configuration of the mold (FIG. 2) described later, the casting 1 is hollow and has a plurality of spaces 3 inside. The plurality of spaces 3 are separated from each other by a plurality of partition walls 5 in the casting 1 (upper ends are indicated by dotted lines). The plurality of partition walls 5 include, for example, ones parallel to the yz plane and ones parallel to the xz plane. The upper and lower ends of each partition wall 5 are connected to the upper and lower surfaces inside the casting 1, and the horizontal ends are connected to the inner wall of the casting 1 and/or another partition wall 5. With such a configuration, the casting 1 can be made lighter and its strength can be secured.

Formed on the upper surface of the casting 1 are a plurality of openings 7 that connect the spaces 3 to the outside of the casting 1. This opening 7 is, for example, as will be understood from the description below, for the convenience of casting, and is not necessarily required for the function of the casting 1. In the illustrated example, one opening 7 is formed for each space 3.

The numbers, positions, shapes, sizes, etc. of the plurality of spaces 3 and the plurality of openings 7 may be appropriately set. In the illustrated example, the plurality of spaces 3 (the plurality of openings 7) are arranged in a matrix in the longitudinal direction (x direction) and the lateral direction (y direction) of the casting 1. The number of arrays in the longitudinal direction (7 in the illustrated example) is larger than the number of arrays in the lateral direction (2).

Although not particularly shown, the plurality of partition walls 5 may include only ones parallel to the yz plane. In other words, the spaces 3 may be arranged in one row in the x direction. An opening may be formed in the partition wall 5 so that the plurality of spaces 3 communicate with each other. Openings may be formed on the side surface and the lower surface of the casting 1. The opening 7 and other openings (not shown) are not only for convenience of casting, but may be essential or convenient in view of the use of the casting 1.

The material of the casting 1 is, for example, so-called cast iron. Therefore, the material of the casting 1 contains iron as a main component, and also contains carbon at a certain ratio (for example, 2.14 wt% or more). Other components of cast iron include silicon, manganese, phosphorus and sulfur. The cast iron may be, for example, flake graphite cast iron (gray cast iron, ordinary cast iron), spheroidal graphite cast iron (ductile cast iron), or other cast iron. However, in the description of the present embodiment, flake graphite cast iron may be taken as an example.

(template)
FIG. 2 is a diagram schematically showing a configuration of a casting system 11 for casting the casting 1. This figure also shows a cross-sectional view of a mold 13 into which a molten metal material (molten metal) that becomes the casting 1 is poured. This cross section corresponds to the line II-II in FIG.

The mold 13 has, for example, a lower mold 15, an upper mold 17 arranged on the lower mold 15, and at least one core 19 arranged between them. Although not particularly shown, the mold 13 may have a basin or the like arranged on the upper mold 17 in addition to the above. Between the members (15, 17, 19 and the like) forming the mold 13 or between the members, for example, a casting part 21 which is a void portion in which the casting 1 is formed, and a gap for guiding the molten metal to the casting part 21. The illustrated gate system is configured.

The mold 13 (lower mold 15, upper mold 17, and core 19) is a so-called sand mold. Specifically, for example, the lower mold 15 has a frame 23 and a sand part 25 arranged in the frame 23. Similarly, the upper mold 17 has a frame 27 and a sand part 29 arranged in the frame 27. The core 19 is, for example, a sand part.

The frames 23 and 27 are made of metal or wood, for example. The sand parts 25 and 29 and the core 19 are made of, for example, sand and a binder that binds the sand. The sand is, for example, silica sand. The binder is, for example, resin, clay or water glass. In the description of the present embodiment, a mode in which the binder is basically a resin, in other words, a mode in which gas is easily generated by pouring the molten metal into the mold 13 is taken as an example. Although not shown in particular, in the sand parts 25 and 29 and the core 19, gaps are formed between the sand grains, so that gas and liquid can flow in (liquid penetrates).

The casting part 21 is configured by a gap surrounded by the sand part 25 of the lower mold 15, the sand part 29 of the upper mold 17, and the core 19. The shape corresponds to the shape of the casting 1 described with reference to FIG. The surface (inner surface) of the sand part 25 of the lower mold 15 and the surface (inner surface) of the sand part 29 of the upper mold 17 have a shape and size corresponding to the shape and size of the outer surface of the casting 1. The cut surface (divided surface) of the lower die 15 and the upper die 17 may be any position between the upper surface and the lower surface of the casting 1, and is the upper surface position in the illustrated example.

The core 19 has a shape and size corresponding to the shape and size of the space 3 and the opening 7. Although not particularly shown, the core 19 is supported by the lower mold 15 at an appropriate portion such as a part of the lower surface and/or a protrusion formed on the side, or by the lower mold 15 and the upper mold 17. It may be positioned by being sandwiched vertically. In addition, in FIG. 1, the illustration of the shape formed by reflecting the shape of the portion corresponding to such positioning in the casting 1 is omitted.

When the molten metal is poured into the mold 13, the heat of the molten metal heats the sand portions 25 and 29 and the resin as the binder in the core 19 to generate gas. The core 19 is formed with a hole 31 for venting the gas. The hole 31 is open to the outside of the mold 13. The shape and size of the hole 31 may be set appropriately. In the illustrated example, the hole 31 linearly extends upward and communicates with the outside of the mold 13 through an opening (reference numeral omitted) formed in the upper mold 17. Although not particularly shown, the hole 31 may have a portion that extends in the horizontal direction or the like, and both ends thereof may be configured to communicate with the outside of the mold 13. Further, although not particularly shown, holes for venting gas may be formed in the outer molds (15 and 17).

(Cooling system)
The casting system 11 has a cooling device 33 in addition to the mold 13. The cooling device 33 is configured to supply a liquid coolant into the mold 13. Examples of the liquid coolant include water. The temperature of the coolant may be appropriately set, and may be, for example, so-called normal temperature (for example, 20° C.±15° C.).

The cooling device 33 includes, for example, a tank 35 that stores a coolant, a pump 37 that delivers the coolant in the tank 35, a relay channel 39 that extends from the pump 37 to the mold 13, and a tip of the relay channel 39. And a head 41 for sprinkling (spraying) the coolant in the mold 13. Further, the cooling device 33 includes a valve 43 located in the middle of the relay channel 39, a temperature sensor 45 for detecting the temperature of the metal material in the mold 13, and a pump 37 and a pump 37 based on the detected value of the temperature sensor 45. And/or a control unit 47 that controls the valve 43.

In the description of the present embodiment, a mode in which the operation of the cooling device 33 (casting system 11) is basically controlled by the control unit 47 is taken as an example. However, part or all of the operation of the cooling device 33 may be performed by an operator instead of the control unit 47. Further, the configuration of the components of the cooling device 33 such as the valve 43 may not be controllable by the control unit 47 but may be controllable by human power. Further, the operation of the control unit 47 described below may be appropriately read as the operation of the operator even if there is no particular mention that the operation may be performed by the operator.

The tank 35 and the pump 37 may have various known configurations. As the tank 35 and the pump 37, or instead of the tank 35 and the pump 37, a facility for supplying cooling water, which is included in a factory in which the mold 13 is installed, may be used. The water supplied from the water supply may be directly supplied to the relay channel 39 without providing the tank 35 and the pump 37. The relay channel 39 may also be various known ones. For example, the relay channel 39 may be a metal pipe or a resin hose.

At least a part of the head 41 is arranged in the hole 31 of the core 19, and the coolant is sprinkled in the hole 31. The configuration of the head 41 may be any suitable one. For example, the head 41 is configured such that a plurality of holes communicating with the inside and the outside of the metal pipe, such as a shower pipe, are formed at a plurality of positions in the longitudinal direction and the axial direction of the pipe. The diameter and length of the pipe and the diameter and number of the holes of the pipe may be set appropriately. In the illustrated example, the diameter of the head 41 is smaller than the diameter of the hole 31 of the core 19, and the outer peripheral surface of the head 41 is separated from the inner surface of the hole 31.

The valve 43 is a flow rate control valve capable of controlling the flow rate of the coolant supplied to the head 41. The configuration of the flow rate control valve may be any known appropriate one. The flow control valve is composed of a solenoid valve or the like, and controls the flow rate by changing its opening degree according to a control signal from the control unit 47. However, as described above, the flow control valve may be one whose opening is controlled by human power.

The temperature sensor 45 is, for example, exposed inside the casting part 21, and thereby detects the temperature of the metal material forming the casting 1. However, the temperature sensor 45 is only required to be able to detect a temperature close to the temperature of the casting 1 as compared with the outside portion of the casting mold 13 and the like, and is not necessarily exposed in the casting 21. For example, the temperature sensor 45 may detect the temperature at a position away from the casting part 21 at a distance of 1/3 or less or 1/5 or less of the distance (for example, the shortest distance) from the casting part 21 to the frame 27 or 23. Good. Further, in the following description, when it is referred to as a detected temperature or the like, the temperature is not only the value as it is (the raw value) detected by the temperature sensor 45, but also the metal material in the casting 21 estimated from the raw value. It also includes the temperature (temperature corrected for the raw value). The temperature sensor 45 may be provided on any of the lower mold 15, the upper mold 17, and the core 19, and the specific arrangement position may be set appropriately. The temperature sensor 45 may have various known configurations, for example, a thermocouple.

The control unit 47 is composed of, for example, a computer including a CPU, a ROM, a RAM, and an external storage device. The CPU executes a program recorded in the ROM and/or the external storage device to construct a functional unit that performs various controls. Although not shown in particular, the control unit 47 has an input device that receives an input operation of the worker and an output device (for example, a display device) that presents various kinds of information to the worker. As described above, the coolant may be supplied from the facility of the factory or the water supply, and in this case, for example, the control unit 47 does not control the pump 37 but only controls the valve 43.

(Supplying coolant to multiple locations)
FIG. 3 is a schematic diagram showing the configuration of the casting system 11 shown together with the top view of the mold 13. In this figure, for convenience of illustration, the connection between the plurality of valves 43 and the plurality of temperature sensors 45 and the control unit 47 is shown only for one valve 43 and one temperature sensor 45. However, the other valves 43 and the temperature sensor 45 are similar to those illustrated. Further, in this figure, the outer edge of the upper end portion of the core 19 (the portion which becomes the inner edge of the opening 7) is also indicated by a dotted line.

The mold 13 has a plurality of cores 19 at positions corresponding to the plurality of openings 7 of the casting 1, for example. Each core 19 has at least one hole 31 for venting gas, for example. As a result, the mold 13 has a plurality of holes 31. The head 41 is arranged in each of the plurality of holes 31. That is, the cooling device 33 supplies the coolant to the plurality of holes 31.

Specifically, for example, the relay flow channel 39 extending from the pump 37 appropriately branches and extends to the plurality of holes 31, and the head 41 is connected to the tips of the plurality of branch flow channels. The branching method may be set appropriately. In the illustrated example, the relay flow channel 39 is divided into rows 31 in each of two rows and seven rows (cores 19), and then, a plurality of holes (here, two) 31 are formed in each row. Every 31 is branched. In other words, the relay channel 39 has a two-stage branch.

More specifically, in the relay channel 39 of the illustrated example, the first channel 39a extends from the pump 37, and the first channel 39a extends in the longitudinal direction of the mold 13. It is connected to the flow channel 39b. A plurality of third flow paths 39c extend to a plurality of rows of holes 31 from a plurality of positions in the longitudinal direction of the second flow path 39b. From each third flow path 39c, two fourth flow paths 39d extend to the two holes 31 in each row.

Although not particularly shown, the relay flow channel 39 may be branched into a plurality of holes 31 from the beginning (in one stage) instead of branching in two stages as in the illustrated example, or conversely, three stages. You may branch by the above. Further, in the relay flow path 39, the first-stage branch is not performed for each row, but the first-stage branch is performed for every plural rows, or the first-stage branch is performed for each column. May be.

The connection position P1 between the first flow path 39a and the second flow path 39b may be located at an appropriate position with respect to the plurality of connection positions P2 between the second flow path 39b and the plurality of third flow paths 39c. .. In the illustrated example, the connection position P1 is a position deviated to one side (one side in the x direction) with respect to the center of the array of the plurality of connection positions P2. That is, the number of connection positions P2 on the −x side and the number of connection positions P2 on the +x side with respect to the connection position P1 are different. Although not particularly shown, the connection position P1 may be located at the center with respect to the array of the plurality of connection positions P2. However, for the sake of convenience due to the facility of the factory and the size of the mold 13, the connection position P1 is a position deviated to one side with respect to the center of the arrangement of the plurality of connection positions P2, as in the illustrated example. It is expected that there will be some cases.

(Control of coolant supply position by position)
The cooling device 33 is configured such that the supply amount of the coolant can be controlled separately for at least one of the plurality of holes 31 and at least one of the plurality of holes 31. In the illustrated example, the valve 43 is provided for each third flow path 39c, and the supply amount of the coolant can be controlled for each row of the plurality of holes 31. From another viewpoint, the cooling device 33 can separately control the supply amount of the coolant between the holes 31 having different positions in the longitudinal direction (x direction) of the mold 13 among the plurality of holes 31. Even if the holes 31 can be controlled separately, the holes 31 may have a mutual influence on the supply amount.

Although not particularly shown, the cooling device 33 may be capable of individually controlling the supply amount of the coolant for each hole 31 (one by one). For example, the valve 43 may be provided for each fourth flow path 39d instead of (or in addition to) the illustrated position. On the contrary, the cooling device 33 may be configured to control the supply amount of the coolant separately for the holes 31 of two or more rows. For example, as shown in the figure, instead of the relay flow channel 39 in which the first-stage branch is formed for each row of the holes 31, a relay flow passage is provided in which the first-stage branch is formed for every two rows or more. The valve 43 may be provided immediately after branching of the eyes.

The temperature sensors 45 are provided at a plurality of positions on the mold 13, for example. In the illustrated example, the temperature sensor 45 is provided for each row of the cores 19. From another viewpoint, the plurality of temperature sensors 45 are provided corresponding to the plurality of valves 43. In still another aspect, one temperature sensor 45 detects a representative value of the temperature of the metal material around the plurality of cores 19 (two here) in each row. From still another viewpoint, the control unit 47 acquires the temperature of the metal material in the mold 13 from the plurality of temperature sensors 45 at a plurality of positions in the longitudinal direction (x direction) of the mold 13.

Although not particularly shown, the plurality of temperature sensors 45 may be more or less than the number of the plurality of valves 43. Further, the plurality of temperature sensors 45 may be provided in a smaller number or a larger number than the number of rows of the plurality of cores 19. In the latter case, each of the plurality of cores 19 may be provided. May be provided.

The relative position of each temperature sensor 45 with respect to the core 19 may be set appropriately. In FIG. 2 and FIG. 3, the temperature sensor 45 is located outside the alignment direction of the plurality of cores 19 (here, two) in each row. However, for example, the temperature sensor 45 may be located below or above the casting part 21 and may be located between the plurality of cores 19 of each row in a plan view. Further, for example, the temperature sensor 45 may be located on the center line of the array of the plurality of cores 19 in each row, or may be arranged deviated from the center line.

The control unit 47 controls the plurality of valves 43 so that the temperature of the metal material to be the casting 1 becomes uniform over the entire longitudinal direction (x direction) based on the temperatures detected by the plurality of temperature sensors 45, for example. Control. That is, the control unit 47 controls the plurality of valves 43 so that the flow rate in the valve 43 corresponding to the temperature sensor 45 that has detected the relatively high temperature is relatively increased. As a result of separately controlling the flow rates in the plurality of valves 43 so that the temperature of the metal material in the casting part 21 becomes uniform, even if the flow rates in some valves 43 become 0 (some valves 43 It doesn't matter) The control based on the detected temperature is performed in real time in one casting, for example. However, the plurality of valves 43 may be controlled based on the detection value of the temperature sensor 45 in the casting performed previously in the casting system 11 having the same configuration.

FIG. 4 is a flowchart showing an outline of the procedure of a casting method using the casting system 11.

In step ST1 (mold preparation step), the mold 13 is prepared. That is, the casting part 21 is configured by combining the lower mold 15, the upper mold 17, and the core 19 which are manufactured in advance. In addition, you may define step ST1 including manufacture of these members. The lower mold 15, the upper mold 17, and the core 19 may be manufactured and assembled by various known methods. The temperature sensor 45 may be embedded when the sand part 25 (or the sand part 29 or the core 19) is manufactured. In step ST1, the cooling device 33 is also arranged on the core 19 of the head 41.

In step ST2 (pouring step), pouring is performed. That is, the molten metal is poured into the casting portion 21 through a gate system (not shown) to fill the casting portion 21. This step may be performed similarly to various known methods. The gas generated from the core 19 and the like by the heat of the molten metal is discharged to the outside of the mold 13 through the holes 31 and the like of the core 19. The hole 31 of the core 19 can also contribute to the discharge of air during pouring.

The molten metal poured into the casting part 21 is cooled by being deprived of heat by the atmosphere via the mold 13, for example. This process may be regarded as performing a cooling step with air (atmosphere).

In step ST3, the control unit 47 (or an operator; hereinafter the same in this flowchart) determines whether or not the temperature detected by the temperature sensor 45 has dropped to a predetermined coolant supply start temperature T2. Then, the control unit 47 continues the cooling by the atmosphere in the case of a negative determination, and proceeds to step ST4 in the case of a positive determination. The detected temperature at this time may be a detected value of any one of the plurality of temperature sensors 45, or may be an average value of the detected values of two or more or all the temperature sensors 45. Good. In the former case, for example, the detected value of the temperature sensor 45 at the position predicted to be the most difficult to cool, or the highest detected value among the plurality of detected values actually detected by the plurality of temperature sensors 45 is used. You may. Also in step ST7 described later, the temperatures detected by the plurality of temperature sensors 45 may be used as in this step.

In step ST4, the control unit 47 starts supplying the coolant to the mold 13. Specifically, for example, the control unit 47 starts driving the pump 37 and opens the plurality of valves 43 at appropriate openings. As already described, depending on the configuration of the cooling device 33, the control unit 47 only opens the plurality of valves 43. The coolant is supplied to, for example, all heads 41 (all cores 19).

The supply amount of the coolant at this time is, for example, an amount sufficient for the coolant to penetrate into the sand grains of the core 19. That is, when the supply amount of the coolant is small, the coolant is immediately evaporated by the heat of the mold 13 and does not penetrate into the sand grains or hardly penetrates into the sand grains, but is supplied in a larger amount than such supply amount. It For example, the coolant is supplied in an amount of at least 1/3, 1/2, or 2/3 of the thickness from the hole 31 of the core 19 to the outer surface (for example, the bottom surface) of the core 19.

Further, the coolant that has permeated between the sand grains may reach the casting part 21 or may not reach it. Further, the coolant may penetrate into the sand portion 25 from the contact portion (not shown) between the core 19 and the sand portion 25 of the lower mold 15, and the core 19 and the sand portion 29 of the upper mold 17 may be mixed. The sand portion 29 may be soaked from the contact portion (shown or not shown). However, the coolant is supplied, for example, in a supply amount that does not or hardly flows out of the mold 13. For example, the amount of the coolant flowing out of the mold 13 is 1/3 or less, 1/10 or less, or 1/20 or less of the amount supplied to the mold 13.

In step ST5 (temperature detection step), the control unit 47 acquires information on detected temperatures from the plurality of temperature sensors 45. Then, in step ST6, the control unit 47 controls the plurality of valves 43 based on the temperature information acquired in step ST5. The control at this time is, for example, as described above, separately controlling the flow rates in the plurality of valves 43 so that the temperatures detected by the plurality of temperature sensors 45 become equal to each other. In addition to this, for example, the control unit 47 may perform feedback control so that the curve drawn by the change in the detected temperature over time follows a predetermined curve.

In step ST7, the control unit 47 determines whether or not the temperature detected by the temperature sensor 45 has dropped to a predetermined coolant supply stop temperature T3. Then, the control unit 47 continues the supply of the coolant in the case of a negative determination, and proceeds to step ST8 in the case of a positive determination.

In step ST8, the control unit 47 stops the supply of the coolant to the mold 13. Specifically, for example, the control unit 47 stops driving the pump 37 and closes the plurality of valves 43.

After that, when the detected temperature drops to a predetermined temperature and/or when a predetermined time elapses, the casting 1 is taken out of the mold 13 (step ST9). In other words, the solution frame is set. At this time, the opening 7 of the casting 1 is used to take out the sand (core 19) in the casting 1 from the inside of the casting 1.

(Coolant supply period)
FIG. 5 is a diagram showing the change over time in the temperature of the metal material in the mold 13.

In this figure, the horizontal axis represents time t (h) and the vertical axis represents the temperature T (°C) of the metal material. The temperature T may be regarded as a detection value of the temperature sensor 45. The solid line L1 indicates the temperature change in the present embodiment. The two-dot chain line L2 shows a part of the temperature change in the comparative example. The two-dot chain line L3 shows a part of the temperature change in the modified example.

Time point t0 corresponds to immediately after pouring. The temperature of the metal material at this time is T0. The specific value of the temperature T0 may be an appropriate value. As an example, the temperature T0 is 1200° C. or higher and 1400° C. or lower.

After pouring, the temperature of the metal material is lowered by cooling by the atmosphere. Immediately after pouring, there is a large temperature difference between the metal material (the mold 13 from another perspective) and the atmosphere. Therefore, heat is easily transferred from the metal material to the atmosphere, and the temperature of the metal material is rapidly lowered. Then, as the temperature of the metal material decreases, the absolute value of the temperature change rate with respect to time gradually decreases.

After that, the temperature of the metal material reaches the A1 transformation temperature T1 (eutectic transformation temperature) (time point t1). For example, in the case of cast iron, the A1 transformation temperature T1 is 720° C. or higher and 730° C. or lower.

The coolant supply start temperature T2 is set to a temperature lower than the A1 transformation temperature T1, for example. For example, the temperature T2 is lower than the temperature T1 by 50° C. or higher, 100° C. or higher, or 200° C. or higher. Further, for example, the temperature T2 may be lower than the temperature at which annealing is generally performed. Taking the case where the metal material to be the casting 1 is flake graphite cast iron as an example, the value of the temperature T2 is illustrated. The temperature T2 is set in the range of 400°C or higher, 450°C or higher, 500°C or higher, or 600°C or higher. The temperature may be set to 650° C. or lower, 600° C. or lower, 500° C. or lower, 450° C. or lower. The lower limit and the upper limit may be appropriately set as long as they do not conflict. For example, the temperature T2 may be set in the range of 400°C to 600°C, or 450°C to 500°C.

When the temperature of the metal material reaches the coolant supply start temperature T2 (time point t2), the supply of the coolant is started as described above. As a result, the temperature of the metal material sharply decreases as compared with immediately before the time point t2. From another viewpoint, the temperature is lower than the temperature (line L2) when the coolant is not supplied.

After that, when the temperature of the metal material reaches the coolant supply stop temperature T3 (time point t3), the supply of the coolant is stopped as described above. The temperature T3 may be set appropriately. When the temperature T3 is set to a relatively low temperature, for example, the time for cooling the mold 13 to near room temperature becomes short. As a result, the time taken to remove the casting 1 from the mold 13 can be shortened. On the other hand, if the temperature T3 is set to a relatively high temperature, it is possible to reduce the probability that a large amount of the non-evaporated coolant will flow out of the mold 13, for example. If the coolant flows out of the mold 13, for example, the coolant may reach other equipment or the like in the factory and affect the work related to the other equipment. Further, for example, if the temperature T3 is set to a relatively high temperature, it is possible to reduce the probability that a large amount of the coolant remains in the mold 13. If a large amount of coolant remains in the mold 13, for example, it takes a long time to dry the sand in order to reuse the sand of the mold 13. Therefore, the temperature T3 may be appropriately set in consideration of the effect of setting it low and the effect of setting it high.

As an example, for example, the coolant supply stop temperature T3 may be a temperature whose difference from the coolant supply start temperature T2 is 300° C. or lower, 200° C. or lower, or 100° C. or lower. And/or the temperature T3 may be 100° C. or higher, 200° C. or higher, or 300° C. or higher. As described above, when the temperature T3 is set higher than the normal temperature, it is possible to reduce the probability that the coolant flows out of the mold 13 or remains in the mold 13 in a large amount.

After the supply of the coolant is stopped, as described above, when a predetermined time elapses and/or when the temperature of the metal material decreases to a predetermined temperature (time point t4), the unraveling work is performed. The temperature T4 at this time may be an appropriate temperature. For example, in the illustrated example, the temperature T4 is depicted as a temperature having a relatively small difference from the coolant supply stop temperature T3 and/or a relatively large difference from the room temperature. For example, the temperature T4 may be a temperature whose difference from the temperature T3 is 300° C. or lower, 200° C. or lower, or 100° C. or lower. And/or the temperature T4 may be 100° C. or higher, 200° C. or higher, or 300° C. or higher. In addition, the unraveling frame may be performed after waiting until the temperature of the metal material decreases to near room temperature, as in the modification shown by the line L3.

As can be understood from the comparison between the solid line L1 and the chain double-dashed line L2 after the time point t2, by supplying the coolant to the mold 13, the timing of the unraveling (time point t4) can be significantly advanced. For example, in the illustrated example, the line L2 does not reach the temperature T4 of the open frame within the illustrated range. This is because when the temperature of the metal material (or the mold 13) that becomes the casting 1 decreases and the difference between the temperature of the metal material and the temperature of the atmosphere decreases, the temperature decrease of the metal material slows down. In an experiment using the casting 1 of about 10 tons by the inventor of the present application, a temperature decrease of 100° C. to 150° C. in a temperature range of 500° C. or lower is promoted by supplying a coolant, and the temperature is 1 day or more or 30% or more. It was confirmed that it is possible to shorten the cooling time.

As described above, the casting method according to the present embodiment includes the mold preparation step (ST1), the pouring step (ST2), and the coolant supply step (for example, after step ST4 to before step ST8). The mold 13 prepared in the mold preparing step includes a lower mold 15 made of a sand mold, an upper mold 17 made of a sand mold, and one or more cores 19 made of the sand mold. The one or more cores 19 have a plurality of holes 31 for venting gas. In the pouring step, the molten metal material is poured into the mold 13. In the coolant supply step, liquid coolant is supplied to the plurality of holes 31 of the mold 13 holding the metal material. Further, in the coolant supply step, the supply amount of the coolant is controlled separately for at least one of the plurality of holes 31 and at least one of the plurality of holes 31.

Therefore, first, the cooling time can be shortened by supplying the coolant. Since the coolant is supplied to the inside (core 19) of the mold 13, the probability that the coolant will flow down the outside of the mold 13 is reduced. Further, by cooling from the core 19 which is located inside the mold 13 and tends to collect heat, the deviation of the temperature of the metal material in the casting part 21 is reduced. Generally, the volume (heat volume) of the lower mold 15 is larger than the volume of the upper mold 17, and heat is likely to be trapped in the lower mold 15. Further, the upper mold 17 may be removed during cooling, and in this case also, the heat of the casting 1 tends to remain below. Therefore, when the liquid coolant infiltrates downward from the inside of the core 19 by gravity, it becomes easy to make the temperature of the metal material in the casting part 21 uniform. Since the hole 31 for degassing is used to supply the coolant to the core 19, no major design change is necessary for the mold 13, which is simple.

Furthermore, since the supply amount of the coolant to the plurality of holes 31 is separately controlled between the holes 31, it is easy to make the temperature of the metal material in the casting 21 uniform. As a result, for example, it is possible to reduce the probability that only a part is rapidly cooled and cracks and/or cavities occur. From another point of view, the probability that only a part of the casting part 21 is rapidly cooled may reduce the supply amount more than necessary, and the temperature of the entire metal material in the casting part 21 may be reduced early. Can be reduced to

Moreover, the casting method according to the present embodiment further includes a temperature detection step (ST5) of detecting temperatures at a plurality of positions of the mold 13. In the coolant supply step (ST4 to ST8), the supply amount of the coolant to the plurality of holes 31 is controlled based on the temperatures at the plurality of positions detected by the temperature detection step (step ST6). In this case, for example, it is easy to make the temperature of the metal material in the casting 21 uniform.

Further, in the present embodiment, in the mold 13, in plan view, the length (x direction) of the casting part 21 which is a space for forming the casting 1 made of a metal material is twice the width (y direction) of the casting part 21. That is all. The plurality of holes 31 include two or more holes whose positions in the longitudinal direction (x direction) of the casting 21 are different from each other. In the coolant supply step (ST4 to ST8), the supply amount of the coolant is controlled separately among the holes 31 having different longitudinal positions.

In the experiment by the inventor of the present application, if the coolant is supplied to the long casting part 21 through the relay channel 39 as shown in FIG. 3 and without the valve 43 for each third channel 39c, the coolant is not supplied. It was confirmed that the probability of cracks occurring in a part of the casting part 21 in the longitudinal direction is higher than in the case. Therefore, for example, the effect of equalizing the temperature of the metal material in the casting part 21 is effectively achieved by controlling the supply amount of the coolant separately among the holes 31 whose longitudinal positions are different from each other. To be demonstrated.

Further, in the present embodiment, the coolant supply step (ST4 to ST8) is started when the temperature of the metal material is lowered to a temperature lower than the A1 transformation temperature T1 (step ST4). More specifically, for example, in the present embodiment, the metal material is flake graphite cast iron, and the coolant supply step is started when the temperature of the metal material decreases to a temperature of 500° C. or lower. Therefore, for example, while shortening the cooling time, it is possible to obtain the casting 1 of the same quality as when the cooling is performed only by the atmosphere without supplying the coolant.

The present invention is not limited to the above embodiments and may be implemented in various modes.

One core may have two or more vent holes. Further, the two or more holes whose supply amounts of the coolant are controlled separately from each other may be arranged in one core. The template may include only one core.

The supply amount of the coolant does not have to be performed in real time based on the detection value of the temperature sensor provided in the mold that has just been poured. For example, based on the detection result of the temperature when casting was performed for the mold of the similar configuration previously, the supply amount is set in advance with respect to the passage of time, and the supply amount is controlled according to the passage of time. Good. Even in this mode, it is possible to reduce variations in temperature at a plurality of positions and to make temperature changes at each position suitable. The control in this aspect is also included in the control in the case of controlling the supply amount based on the detected temperature. In another aspect, the temperature sensing step may not occur during the coolant supply step. From still another viewpoint, the temperature sensor may not be provided in the mold that is currently being poured.

The above applies not only to the flow rate control in step ST6 but also to the coolant supply start in step ST3 and the coolant supply stop in step ST7. That is, the timing of starting and/or stopping the supply of the coolant is set based on the detection result of the temperature when casting was performed before, and depending on whether or not the time has come, the supply start and/or The supply may be stopped. The supply start in such a mode is also included in the start when the temperature of the metal material is lowered to a temperature lower than the A1 transformation temperature, for example.

In the embodiment, the core is composed of only the sand part. However, the core may have a portion other than the sand portion. For example, the core may have a vipe which is inserted into the sand part and whose inside constitutes a vent hole. The pipe forming the vent hole may have, for example, a plurality of holes that communicate the inside and outside of the pipe so that the coolant can penetrate into the sand portion. The pipe having such a plurality of holes may also serve as the head 41 that sprinkles the coolant shown in the embodiment, or may be a pipe different from the head 41 into which the head 41 is inserted. The pipe forming the vent hole may be made of, for example, a heat-resistant material such as carbon steel or ceramic, and may contribute to reducing the probability of the core (sand part) losing its shape. ..

In the embodiment, the coolant was supplied in an amount sufficient to penetrate the sand. However, the coolant may be supplied in a relatively small amount that evaporates without penetrating into the sand portion. Conversely, the coolant may be provided in a relatively large amount so that it flows out of the mold in a relatively large amount.

In the embodiment, the aspect has been described in which the supply amount of the coolant is controlled so that the temperature of the metal material in the casting is equalized. However, depending on the specific aspect of the casting, the temperature of a part of the metal material in the casting part may be lowered early or, on the contrary, the supply amount of the coolant may be delayed so as to delay the drop of a part of the temperature. You may control.

From the present disclosure, the following concept can be extracted, which is not premised on the supply of the coolant to the vent hole.
(Concept 1)
A mold preparation step of preparing a mold including a lower mold composed of a sand mold and an upper mold composed of a sand mold,
A pouring step of pouring a molten metal material into the mold;
A coolant supply step of supplying a liquid coolant to the mold holding the metal material;
Has
The casting method, wherein the coolant supply step is started when the temperature of the metal material drops to a temperature lower than the A1 transformation temperature.

DESCRIPTION OF SYMBOLS 1... Casting, 13... Mold, 15... Lower mold, 17... Upper mold, 19... Core, 31... Gas vent hole, 43... Valve.

Claims (6)

A mold that includes a lower mold made of a sand mold, an upper mold made of a sand mold, and one or more cores made of the sand mold, and a plurality of holes for degassing are formed in the one or more cores. A mold preparation step to prepare
A step of pouring a molten metal material into the mold,
A coolant supply step of supplying a liquid coolant to the plurality of holes of the mold holding the metal material,
Has
A casting method, wherein in the coolant supplying step, the supply amount of the coolant is controlled separately for at least one of the plurality of holes and at least one of the plurality of holes. The method further comprises a temperature detection step of detecting temperatures at a plurality of positions of the mold,
The casting method according to claim 1, wherein in the coolant supply step, the supply amount of the coolant to the plurality of holes is controlled based on the temperatures of the plurality of positions detected by the temperature detection step. In the plan view, the length of a casting part, which is a space for forming a casting made of the metal material, is at least twice the width of the casting part in plan view,
The plurality of holes include holes having different positions in the longitudinal direction of the casting,
The casting method according to claim 1 or 2, wherein in the coolant supply step, the supply amount of the coolant is controlled separately among the plurality of holes having different positions in the longitudinal direction. The casting method according to claim 1, wherein the coolant supply step is started when the temperature of the metal material drops to a temperature lower than the A1 transformation temperature. The metal material is flake graphite cast iron,
The casting method according to claim 4, wherein the coolant supply step is started when the temperature of the metal material drops to a temperature of 500°C or lower. A mold that includes a lower mold made of a sand mold, an upper mold made of a sand mold, and one or more cores made of the sand mold, and a plurality of holes for degassing are formed in the one or more cores. When,
A cooling device capable of supplying a liquid coolant to the plurality of holes,
Has
The casting system has a plurality of valves so that the supply amount of the coolant can be separately controlled by at least one of the plurality of holes and at least another of the plurality of holes.

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