JPS60199562A - Casting method of low melting alloy - Google Patents

Abstract

PURPOSE:To improve finishing accuracy of a casting by incorporating heat sensors in the casting and gas ejectors for cooling and heaters in a casting mold and averaging the internal temp. of the casting during solidifying. CONSTITUTION:Electric heaters 6 and gas ejectors 5 for cooling are disposed in casting molds 1, 2 and heat sensors 9 are embedded in a casting. The temp. in the slow cooling stage from the radiation down to an ordinary temp. in the stage when each part of the casting solidifies is measured by the sensors 9 with lapse of time and the temp. measured signal is applied to a computer. The computer ejects a cooling gas from the ejectors 5 to the point where the temp. is higher than the average temp. in the casting at the point of the time when the temp. is measured. The computer heats additionally the point where the temp. is lower than the average temp. by the heaters 6. The casting is thus slowly cooled while the temp. over the entire part thereof is averaged and is cast.

Description

[Detailed description of the invention] The present invention relates to a method for casting low melting point alloys.

Conventional casting methods for low melting point alloys use a riser or chiller in order to prevent underfilling or shrinkage defects due to shrinkage during solidification, and as a countermeasure for casting defects, extra thickness is added to the deaf material to compensate. Alternatively, in order to move the position of the defective part, a heating agent was used locally in the mold, a heat insulating material was used, or a heater was used to replenish the heat. Furthermore, casting materials have been made to have thermal shock resistance, ceramic mold materials that can minimize the amount of thermal deformation have been used, and heat-resistant binders have been used. However, with either method, it is nearly impossible to achieve dimensions of n degrees for large castings. Even if the shrinkage rate, which varies depending on the material of the casting material, is known accurately, the shape and wall thickness of the casting may vary.
If this change occurs, the calculated contraction or change may not occur. In addition, in the case of irregularly shaped special objects,
#The time it takes for the temperature to drop from solidification to room temperature during loading differs locally - in other words, temperature differences within the same barrel cause thermal stress, and the casting Always causes twisting. Until now, no construction method has been established that is theoretically acceptable for twisting, and normally ±1.
It is considered that the limit is to cast with an accuracy of ±4 mm per 2 m, and in general cast products, deformation or twisting of 5 to 10 mm per 1 m and 7 to 15 mm per 2 m occurs.

When casting a low melting point alloy, the present invention incorporates a heat sensor inside the casting, and also incorporates a cooling gas jet and a heater inside the mold to average the temperature inside the casting during solidification. This invention aims to improve the finishing accuracy of castings by doing this.

Embodiments of the present invention will be described with reference to the drawings.

(1) is the upper part of the mold, (2) is the lower part of the mold that faces the upper mold part (1), and there is a recess (2) inside the #-shaped lower part (2).
a) is formed, and the molding order metal (2a) is formed in the recessed part (2a).
3) Convex ceramic 1lf with breathability that includes
41 is fixed.

And Shizuku! The bottom part inside the B upper part (1) (the left and right sides (2b) in the lalJe type lower part (2)) and the bottom part (2
-F side of c) and the left and right sides (3a
) (3a) and the upper part of the mold (]) and the lower part of the mold (2).
A cooling gas jet (5) and an electric heater (
6), bury a plurality of each. The cooling gas ejector (5) has a large number of ejection holes (5a) bored in a pipe (7) that is connected to a device (not shown) that supplies a cooling gas such as nitrogen gas. It is formed by connecting the head (5b). The electric heater (6) is connected to a power source (not shown) (8).Furthermore, a cooling gas jet (5) is provided in the recess (2a) of the lower part (2) of the casting. ) A heat sensor f-(9) is installed at a position close to and facing each of the heat sensors f-(9), and each heat sensor (9) is connected to a temperature measuring computer (not shown).

In the figure, aO is a leather grain pattern.

Next, to explain the casting method according to the present invention, an electromotive force is generated in each thermal sensor (9) at the same time as the zinc alloy in a melt state is poured into the recess (2aH) of the lower part of the mold (2). The electromotive force is guided to the ADi converter, converted into a digital signal, and inputted to the temperature measurement angle computer.
9) and calculate the average temperature. Then, for a part of the casting whose temperature is higher than the average temperature, an "open" signal is commanded to the electromagnetic valve that operates the cooling gas jetter (5) closest to the part, and cooling gas is jetted out. Cooling gas is ejected from the vessel (5). The ejected cooling gas permeates around the ejector (5) and locally lowers the heat in the casting (a) to the average temperature. In addition, for parts of the casting where the temperature is lower than the average temperature, a signal is given to the electric heater (6) placed closest to the part, and the electric heater (6) is energized via a relay to heat it. , the area is raised to an average temperature. In this way, thermal sensors embedded in various parts of the casting begin to solidify.
(9), the temperature at each location is measured at intervals of 30 seconds or 1 minute, the average temperature of the casting is calculated by a computer, and the cooling gas placed at the location is applied to the location where the temperature is higher than the average temperature. A command from the computer is given to the blower (5) to blow out the cooling gas, and the ambient air with thermal energy latent in the upper part of the mold or the lower part of the mold (2) around the part is used for casting. When a locally low-temperature boundary area is created, the heat drop between that boundary area and the part of the casting facing it increases, more heat is released from that boundary area, and the casting process gradually increases. The heat drop between the general part of the object and its boundary area, as well as the heat transfer inside the casting, converge to bring the temperature close to the average temperature. On the other hand, for a location with a temperature lower than the average temperature, the heat sensor (9) and computer command the electric heater (6) placed at that location to turn on electricity to generate heat. As the temperature of the mold and the atmosphere rises, the level of thermal energy that is to be released from the casting is higher than the level of thermal energy that is to be released from the casting, which prevents the casting from releasing heat, so cooling must be carried out by normal heat radiation or forced control from other high-temperature parts. Combined with heat dissipation, low temperature areas also converge to an average temperature.

Therefore, according to the present invention, by controlling the heat dissipation of the mold at the same time as the start of casting, the temperature of the cast is balanced and cooled, thereby preventing the generation of thermal stress and ensuring uniform shrinkage without twisting. It is possible to obtain highly accurate castings,
For example, for a 1 m casting, Q, about 3 mm, 2 m
It is possible to cast with an accuracy of about 0.5 mm, and the cutting edge can be made with extremely high precision compared to conventional methods. Therefore, the profiling and finishing processes that were conventionally required after machining the rough material and before assembling can be omitted, for example, using resin molding molds (INJ, BMO, BMO) or thin steel sheets of 1.2m to 2.3B. It is possible to use casting to achieve precision through the plate thickness of various male and female dies such as press drawing dies or molding dies for processing, and the production time and time is half of that of conventional methods. The cost is also 2
It is reduced to one to one third, and the industrial significance of improving the flexibility is extremely large.

[Brief explanation of drawings]

The figure is a cross-sectional view of an apparatus for making a top mold according to the present invention. Code 1・・・・・・・・・ Upper part of prayer type 5・・・・・・
......Cooling gas 2゜19.1910310.
Casting, 6a Squirt 2a...Concave part 5
a...Blowout holes 2b, 2b... Side part 5b... Head part 2c...
・・・・Bottom part 6・・・・・・・・・・Electric heater! ,-exposure/molding cold metal 7 ・・・ ・・
Pipe 3... 3. Head... side 8...
・・・・・・・・・ Conductor 4・・・・・・・・・・・・
・Ceramic 9・・・・・・・・・Thermal sensor mold. 99110011811. Leather, 15 patterns I...Cast March 23, 1980 Inventor Hei 1) Reitsu Department agent Masu Takaaki Torii

Claims (1)

[Claims] An electric heater and a cooling gas jet are placed inside the casting mold, and a heat sensor is installed inside the casting to measure the temperature during the slow cooling process from heat dissipation when each part of the casting solidifies to room temperature. is measured over time by a heat sensor, and the temperature measurement signal from the heat sensor is sent to a computer. Cooling gas is injected from a cooling gas injector into areas where the temperature inside the casting is higher than the average temperature at the time of measurement of the temperature change. The temperature of the entire casting is balanced by cooling it forcibly by ejecting water, supplementing heat with an electric heater in areas where the temperature is lower than the average temperature, and controlling the thermal energy stored in the mm surrounding the casting. A precision casting method for a low melting point alloy, characterized by casting while cooling;