Manufacturing method for cast products
By sealing a rough casting in a pressurized water environment with controlled water glass concentration, the method effectively breaks and discharges cores from castings, addressing the inefficiencies of traditional core removal methods.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2023-03-22
- Publication Date
- 2026-05-19
AI Technical Summary
Existing core removal methods face challenges where humidified gas fails to penetrate the sand core, leading to insufficient strength reduction and difficulty in breaking and discharging the core.
A method involving sealing a rough casting in a container immersed in water, maintaining pressure above atmospheric pressure by heating, and using water with a specific water glass concentration to facilitate core disintegration.
Enables easy and efficient core discharge without the need for additional impact or vibration, enhancing core removal efficiency.
Smart Images
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Abstract
Description
Technical Field
[0001] This disclosure relates to a method for manufacturing a casting product.
Background Art
[0002] In the core removal method disclosed in Patent Document 1, the strength of the sand core formed with a binder containing water glass in the rough casting is reduced by supplying a cooled humidified gas to the sand core. Then, an impact force is applied to the rough casting by an impact device to break the sand core. Further, the broken sand core is discharged from the rough casting by vibration by a vibration device. The core removal method disclosed in Patent Document 1 can be suitably used for casting products.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] The inventors of the present application have found the following problems. In such a core removal method, there are cases where the humidified gas does not reach the inside of the sand core and the strength of the sand core does not sufficiently decrease. Therefore, it may not be easy to break and discharge the sand core.
[0005] This disclosure has been made in view of the above problems, and provides a method for manufacturing a casting product that can easily discharge cores from a casting blank.
Means for Solving the Problems
[0006] The method for manufacturing a casting product according to this disclosure is a step of sealing a rough casting formed by casting using a core in a container immersed in water, The process involves heating the water in the container while the casting material is sealed, thereby maintaining the pressure inside the container above atmospheric pressure to break the core and form core sand. The process includes a step of removing the core sand from the casting material.
[0007] Furthermore, the core may be an inorganic core, and the inorganic core may include a binder and an aggregate, wherein the binder may include water glass.
[0008] Furthermore, in the process of forming the core sand, the pressure inside the container may be maintained at 0.15 MPa or higher.
[0009] Furthermore, the water in the container may contain water glass, and the water glass concentration in the water in the container may be characterized by being 3% or more and 5% or less by mass. [Effects of the Invention]
[0010] According to this disclosure, the core can be easily discharged from the casting material. [Brief explanation of the drawing]
[0011] [Figure 1] This is a flowchart showing the method for discharging the core according to Embodiment 1. [Figure 2] This table shows the water glass concentration, water temperature, pressure inside the container, and core disintegration rate for Examples 1-4 and Comparative Example 1. [Figure 3] This graph shows the nexon collapse rates of Examples 1-4 and Comparative Example 1. [Figure 4] This figure shows an example in which the core discharge method according to Embodiment 1 is applied. [Modes for carrying out the invention]
[0012] The inventors focused on the fact that atmospheric pressure in the core environment affects the disintegration properties of the core, and after diligently investigating various factors including atmospheric pressure, they came up with the present invention.
[0013] Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. Also, for clarity of explanation, the following description and drawings are simplified as appropriate.
[0014] <Embodiment 1> Referring to FIG. 1, a method for discharging neutrons according to Embodiment 1 will be described.
[0015] Seal the casting rough material in a container immersed in water (step ST1).
[0016] The container preferably has an internal space capable of sealing water and the casting rough material and is capable of heating the internal space. The container may be configured such that the pressure inside the container exceeds atmospheric pressure, for example, it may be equipped with a heating device for heating water, for example, a pressure cooker.
[0017] Also, the water in the container preferably contains water glass. The water glass concentration of the water in the container is preferably 1% or more and 5% or less, more preferably 3% or more and 5% or less, in mass%. The water glass concentration can be changed by adding water glass solids to water.
[0018] Also, the casting rough material is formed by casting using neutrons. The casting rough material has an internal space in which neutrons are arranged. The casting rough material is made of a metal material, for example, pure aluminum or an aluminum alloy. The casting method for forming the casting rough material is not particularly limited and can be selected from various casting methods, for example, gravity casting method, low-pressure casting method, die-cast casting method, suction casting method.
[0019] Also, the core is preferably water-soluble. For example, the core contains water glass as a binder. The core is preferably an inorganic core. For example, the core contains a binder and an aggregate, and the aggregate contains sand. The inorganic core may further contain additives or the like as required. An example of the method for manufacturing the core will be described. First, materials such as an aggregate and a binder are kneaded to form a kneaded product. Further, this kneaded product is filled into the cavity of a core mold. Furthermore, the filled kneaded product is heated and cured to form a core. For this heating and curing, the core mold may be heated using a heater, irradiated with microwaves to heat the kneaded product and the core mold made of resin, or heated by blowing hot air into the cavity of the core mold. Finally, the core is taken out of the core mold.
[0020] Subsequently, while keeping the casting rough material sealed, the water in the container is heated so that the pressure in the container is maintained to exceed atmospheric pressure to break the core and form core sand (step ST2). It is preferable that superheated steam is generated in the container by this heating.
[0021] The pressure in the container is preferably maintained to exceed atmospheric pressure, for example, 0.10 MPa. Specifically, it is preferably maintained at 0.15 MPa or 0.16 MPa or more. Also, the heating time for heating the water in the container may be determined empirically as appropriate according to the surface area and volume of the core and the like.
[0022] The water in the container preferably contains water glass, and the water glass concentration of the water in the container is preferably 1% or more and 5% or less, more preferably 3% or more and 5% or less, by mass%.
[0023] Finally, the core sand is discharged from the casting rough material (step ST3). For example, water may be flowed onto the core sand to discharge the core sand from the casting rough material. In step ST2, if a part of the core remains without being broken, a part of the remaining core may be discharged from the casting rough material as appropriate using a vibration device or a striking device.
[0024] Based on the above, by heating the water inside the container while the casting material is sealed, the pressure inside the container is maintained to exceed atmospheric pressure. As a result, superheated steam can come into contact with the core and reach the inside of the core. This causes the core to be subjected to pressure while its strength is sufficiently reduced. Consequently, the core is broken and core sand is formed. Since the core sand is a granular material, it can be easily moved from the internal space of the casting material to the outside of the casting material by flowing water through it. In other words, the core can be easily discharged from the casting material.
[0025] Furthermore, according to the configuration of the core discharge method of this embodiment 1, the pressure inside the container and the water glass concentration of the water inside the container are limited to a predetermined range, thereby enabling the further formation of core sand. For example, if almost all of the core is destroyed in step ST2 to form core sand, the core can be discharged from the casting material without applying impact force or vibration to the core. In other words, the core can be easily discharged from the casting material without using a vibration device or a striking device.
[0026] Furthermore, the core discharge method according to Embodiment 1 is preferably incorporated into a method for manufacturing cast products. In such a method for manufacturing cast products, the core can be easily discharged from the casting material, and the cast product can be manufactured. [Examples]
[0027] Next, referring to Figures 2 and 3, we will explain the results of verifying steps ST1 and ST2 of an example of a core discharge method according to Embodiment 1.
[0028] In Examples 1 to 4, the processes corresponding to steps ST1 and ST2 in the core discharge method according to Embodiment 1 were carried out, and the core collapse rate was determined. The results are shown in Figures 2 and 3.
[0029] The core decay rate RC can be calculated by determining the difference between the core weight W0 before the experiment and the core weight W1 after the experiment, and then dividing this difference by the core weight W0 before the experiment. In other words, the core decay rate RC can be calculated using the following relationship. RC = (W0 - W1) / W0
[0030] Core specimens were formed by heating and curing a mixture containing recycled inorganic core sand in a muffle furnace at a mold temperature of 260 degrees Celsius. The inorganic core contained water glass. The core specimens were then allowed to cool to below 100 degrees Celsius. A pressure cooker was used as the container. This pressure cooker was equipped with a lid, which had a thermometer and a pressure gauge attached. The core specimens were placed on a mesh and then placed inside the pressure cooker. The process corresponding to step ST2 was carried out under the conditions shown in Figure 2, namely, the water glass concentration in the water inside the container, the water temperature, and the pressure inside the container. The heating times for Examples 1 to 4 were 1 min, 5 min, 5 min, and 5 min, respectively. The weight of the core before being placed on the mesh was defined as core weight W0, and the weight of the core remaining on the mesh was defined as core weight W1.
[0031] In Comparative Example 1, the core disintegration rate was determined by performing a core disintegration method different from that of Embodiment 1. The results are shown in Figures 2 and 3. In this alternative core disintegration method, first, a core test specimen is placed in a container filled with water. The container is not sealed and is open to the atmosphere. Furthermore, the pressure inside the container is maintained at atmospheric pressure by heating the water inside the container. The core test specimen and container used in Comparative Example 1 are the same as those used in Examples 1 to 4. The alternative core disintegration method was performed under the conditions shown in Figure 2, namely, the water glass concentration of the water in the container, the water temperature, and the pressure inside the container.
[0032] As shown in Figure 3, the core collapse rates in Examples 1-4 were 40% or higher, which was a good value. On the other hand, the core collapse rate in Comparative Example 1 was 16%, which is lower than that in Examples 1-4. One reason for this is that in Examples 1-4, the pressure inside the container was higher and maintained above atmospheric pressure compared to Comparative Example 1.
[0033] Furthermore, in Examples 2-4, the core disintegration rate was 57% or higher, which was an even higher value. One reason for this is that, compared to Example 1, Examples 2-4 had a higher water glass concentration in the water inside the container, ranging from 1% to 5% by mass.
[0034] Furthermore, in Examples 3 and 4, the core disintegration rate was 96% or higher, which was remarkably high. One reason for this is that, compared to Examples 1 and 2, Examples 3 and 4 had a higher water glass concentration in the water inside the container, ranging from 3% to 5% by mass.
[0035] Next, with reference to Figure 4, Example 5, which applies an example of the core discharge method according to Embodiment 1, will be described.
[0036] In Example 5, a cylinder head casting was used as the raw material. This cylinder head casting was more complex in shape and larger in size compared to the core test piece described above. An inorganic core containing water glass was used as the core. The cylinder head casting was formed using a low-pressure casting method. The water glass concentration in the water in the container was 5% by mass. The maximum temperature of the water in the container was 122°C. The cylinder head casting was heated to 120°C or higher for 5 minutes.
[0037] The cylinder head casting material was left in the air for two weeks in its as-cast state, and then stored for two weeks in a dry environment using a desiccant. In other words, the cylinder head casting material was placed in an environment where cores were more likely to remain compared to a normal manufacturing line. The cylinder head casting material was cut and divided into parts C1, C2, and C3. An example of a core removal method was performed on each part C1, C2, and C3. The cylinder head casting material was not subjected to vibration or impact using a vibration device or impact device. Figure 4 shows the parts C1, C2, and C3 of the cylinder head casting material before and after performing the example of a core removal method.
[0038] As shown in Figure 4, in section C1 of the cylinder head casting before the procedure, the core R1 remained and was adhering to the inner wall surface of the internal space of section C1. On the other hand, in section C1 of the cylinder head casting after the procedure, neither the core R1 nor the sand could be found. In other words, the core R1 could be easily removed from section C1. In addition, the cores R2 and R3 that remained in sections C2 and C3 of the cylinder head casting before the procedure could also be easily removed from sections C2 and C3, respectively, in the same way as the core R1. From the above, the cores R1, R2, and R3 could be removed from the cylinder head casting without applying impact force or vibration to the cores R1, R2, and R3. In other words, the cores R1, R2, and R3 could be easily removed from sections C1, C2, and C3 of the cylinder head casting.
[0039] It should be noted that the present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. Furthermore, the present invention may be implemented by combining the above embodiments or examples thereof as appropriate. [Explanation of symbols]
[0040] R1, R2, R3 Core C1, C2, C3 Cylinder head casting material parts ST1, ST2, ST3 process
Claims
1. A process of sealing a casting material formed by casting with a core into a container immersed in water, The process involves heating the water in the container while the casting material is sealed, thereby generating superheated steam inside the container, maintaining the pressure inside the container above atmospheric pressure to break the core, and forming core sand. The process includes a step of removing the core sand from the casting material, In the process of forming the core sand, The temperature of the water in the container is between 117°C and 122°C. A method for manufacturing cast products.
2. The aforementioned core is an inorganic core, The inorganic core includes a binder and aggregate. The aforementioned binder includes water glass, A method for manufacturing a cast product according to claim 1.
3. In the process of forming the core sand, The pressure inside the container shall be maintained at 0.15 MPa or more and 0.16 MPa or less. A method for manufacturing a cast product according to claim 1 or 2.
4. The water in the container contains water glass. The water glass concentration of the water in the container is 3% or more and 5% or less by mass. The meson collapse rate is 96% or higher. A method for manufacturing a cast product according to claim 1 or 2.