JPS62161458A - Method and apparatus for casting - Google Patents

Abstract

PURPOSE:To effectively heat and hold a molten metal and to make mass production of castings having good quality by providing an electromagnetic induction pump to a feed pipe and transferring the molten metal by the electromagnetic force thereof. CONSTITUTION:The molten metal level in the feed pipe 14 is detected by a molten metal level sensor 44 which inputs a detection signal to a microcomputer 48 so as to be subjected to arithmetic processing. The resulted output command is transmitted via an amplifier 60 to a voltage controller 42 with controls the excitation voltage of an excitation coil 40 of the electromagnetic induction pump. The molten metal in the pipe 14 is injected in accordance with a prescribed injection program. The molten metal therein is maintained at a specified level after the completion of casting. The sensor 44 energizes a servocontrol motor 46 by which the sensor 44 is lowered until the sensing part thereof contacts the molten metal surface A.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a low-pressure casting system, and particularly to a casting method and apparatus with improved molten metal pumping means and molten metal pumping pressure control.

[Conventional technology]

As a conventional low-pressure casting system, an apparatus is known in which a molten metal pipe is led out from a molten metal holding furnace having an airtight structure, and the molten metal is directly injected into a mold cavity from the molten metal pipe at low pressure using air pressure.

FIG. 2 shows an example of the construction of a casting apparatus using the conventional pneumatic control method. That is, in Figure 2,
Reference numeral 10 indicates a molten metal holding furnace, and this holding furnace 10 is hermetically sealed by a cover plate 12. However, a hot water supply pipe 14 is airtightly inserted through a part of this M4 wire, and an air pressure supply system 16 is connected thereto. Air pressure supply system 16,
It is configured to introduce pressurized air generated from a required air pressure source 18 into the holding furnace 10 via an air pressure control device 20. On the other hand, the hot water supply pipe 14 is connected to the fixed goi plate 22.
It is communicated and connected to the hot water passage 26 of the lower mold 24 via. An upper mold 28 is joined to the upper part of the lower mold 24, and a mold cavity 30 is provided between the L mating surfaces. Further, a gas burner 32 is disposed on the outer periphery of the portion of the hot water supply pipe 14 led out from the cover plate 12, and the mold cavity 3
The structure is such that solidification of the molten metal in the hot water supply pipe 14 is prevented during the holding time until the molten metal solidifies after the completion of casting the molten metal into the hot water supply pipe 14.

In the conventional low pressure casting equipment configured in this way,
Air pressure 11 (controlled air pressure is supplied from the yarn feeder 16) to the holding furnace 10 having an airtight structure, and casting is performed under a constant injection pressure of the melt field from the hot water supply pipe 14 into the mold cavity 30. In this case, after the casting cycle is completed, the air pressure supplied from the air pressure supply system 16 is released, so the molten metal in the hot water supply pipe 14 flows back into the holding furnace 10, and the molten metal level B is the molten metal level A of the holding furnace 10. will be at the same level.

[Problem that the invention seeks to solve]

According to the conventional casting apparatus described above, the injection pressure of the molten metal is kept at a constant condition by controlling the air pressure to the holding furnace 10, so the response to the injection control of the molten metal is slow and the casting cycle time is shortened. There are increasing difficulties. Furthermore, when programmatically controlling the injection pressure during injection of molten metal into the mold cavity 30, controllability decreases for the same reason and precise control is not possible, making it difficult to mold cast products with complex shapes. However, there are disadvantages in that the molten metal cannot flow sufficiently into the cavity at the tip of the mold, resulting in defective products. Further, in each casting cycle, the level B of the molten metal in the hot water supply pipe 14 fluctuates up and down due to switching of air pressure control, which causes air to be drawn into the molten metal in the hot water supply pipe 14, resulting in a cast product. There are disadvantages such as the formation of nests.

Therefore, an object of the present invention is to use an electromagnetic induction pump in place of conventional air pressure control, control the injection pressure of molten metal, and optimally hold the molten metal in the hot water supply pipe and holding furnace to ensure smooth casting work. The purpose of the present invention is to provide a casting method and apparatus that can achieve this and consistently obtain cast products of stable quality.

[Means for solving problems]

The casting method according to the present invention is a casting method in which molten metal in a holding furnace is poured directly into a mold cavity through a hot water supply pipe at low pressure, and an electric induction pump is disposed in a part of the hot water supply pipe. A movable hot water level detection sensor is provided in the holding furnace, the hot water level detection sensor detects the hot water level in the holding furnace,
Based on this detection signal, the excitation voltage of the electromagnetic induction pump is calculated, commanded, and controlled in order to set the injection pressure when pouring metal into the mold cavity from the hot water supply pipe and to maintain the molten metal in the hot water supply pipe at an optimal level. It is characterized by

Further, the casting apparatus according to the present invention for carrying out the above method has an excitation coil that constitutes an electromagnetic induction pump arranged in a position close to the mold cavity of the hot water supply pipe, and on the other hand, a hot water level in the holding furnace. A hot water level detection sensor is installed so that it can be moved up and down, and the hot water level detection signal is input to set the injection pressure and control the molten metal in the hot water supply pipe when pouring metal from the hot water supply pipe into the mold cavity. A means for calculating an excitation voltage trI command of the electromagnetic induction pump to maintain it at an optimum level is provided, and a voltage controller is further provided for energizing and controlling the excitation coil according to an excitation voltage command obtained by the calculation means. Features.

[Effect]

According to the casting method and apparatus of the present invention, an electromagnetic induction pump is provided in the hot water supply pipe and the hot water is transferred by its electromagnetic force. G? & Addition 3: Electromagnetic induction is used to enable effective holding and to detect the level of the molten metal in the holding furnace, so that appropriate injection pressure and injection amount can always be obtained based on this detection signal. By controlling the excitation of the pump, it is possible to mass-produce high-quality castings.

〔Example〕

Next, the casting method according to the present invention will be described in detail by exemplifying an apparatus for carrying out this method.

FIG. 1 shows an embodiment of the casting apparatus of the present invention. For convenience of explanation, the same components as those of the conventional casting apparatus shown in FIG. 2 will be described with the same reference numerals. In FIG. 1, the molten metal holding furnace 10. The configurations of the hot water pipe 14 and the molds 24 and 28 are similar to those of the conventional apparatus.

The present invention is characterized in that an electromagnetic induction pump is provided in the vicinity of the hot water supply pipe 14 where it is communicatively connected to the fixed die plate 22. For this reason, in this embodiment, the hot water supply pipe 14 is led out from the side surface of the bottom of the holding furnace 10, and the excitation coil 40 of the electromagnetic induction pump is arranged around the rising part of the hot water pipe 14 at a position close to the fixed guide plate 22. be. However, this electromagnetic induction pump transfers the molten metal by electromagnetic force and injects it into the mold cavity 30 by adjusting the excitation voltage of three-phase alternating current or the like supplied to the excitation coil 40 by the voltage controller 42. It works like that. In this case, the following control system is employed to control the voltage controller 42.

That is, reference numeral 44 is a hot water level detection sensor inserted into the holding furnace 10 from the lid plate 12 so as to be vertically movable;
The movement of the hot water level detection sensor 44 is controlled by a servo motor 46. This servo motor 46 is controlled based on a command signal output from a microcomputer 48.
This is performed using the j8 signal output from the amplifier 50.

Further, the pulse generator 52 is coupled to the servo motor 42, detects the vertical position of the hot water level detection sensor 44, and inputs this detected position signal to the microcomputer 48.

Roughly speaking, a detection signal for detecting contact with the hot water level by the hot water level detection sensor 44 is inputted to the microcomputer 48 via the converter 54 .

Therefore, the microcomputer 48 inputs the injection pressure and the programmatic change pattern of the injection pressure as the optimum casting conditions through the input means 56 such as a keyboard while checking the CRT display device 58 as appropriate. , compares the data on the molten metal level position in the holding furnace 10 inputted from the pulse generator 52, calculates the optimum injection conditions for the molten metal, and outputs a control command for the electromagnetic induction pump. Therefore, the control command output by this microcomputer 48 is transmitted to the voltage controller 4 via the amplifier 60.
2, the excitation coil 40 of the electromagnetic induction pump is energized. Note that reference numeral 62 indicates a power source for driving the servo motor 46 that moves the excitation coil 40 and the hot water level detection sensor 44 of the electromagnetic induction pump.

In the casting apparatus of this embodiment, the hot water level B in the hot water supply pipe 14 is determined by inputting the detection signal from the hot water level detection sensor 44 to the microcomputer 48 for arithmetic processing, and using the obtained output command. Voltage controller/
By controlling the excitation voltage of the excitation coil 40 of the electromagnetic induction pump, the molten metal in the hot water supply pipe 14 is injected based on a predetermined injection program, and after completion of casting, the molten metal level B is maintained at a constant level. It is possible to maintain the In this case, the hot water level detection sensor 44 energizes the servo motor 46 until its sensing portion contacts the hot water level, and the sensor 44
Move down until it comes into contact with the hot water surface A. At this time, the temperature sensor or energization sensor that constitutes the sensing part of the hot water level detection sensor 44 is activated, and its output is sent to the microcomputer 48 via the converter 54, and the output from the microcomputer 48 is sent via the amplifier 50. A command to stop driving the servo motor 46 is output. At the same time, the position signal detected by the pulse generator 52 coupled to the servo motor 46 is input to the microcomputer 48, and based on this hot water level data, the excitation coil 40 of the electromagnetic induction pump is adjusted to Performs arithmetic processing to determine.

〔Effect of the invention〕

As is clear from the embodiments described above, according to the present invention,
The electromagnetic induction pump makes it possible to maintain the molten metal at a constant level in the hot water supply pipe regardless of changes in the level of the molten metal in the holding furnace, making it possible to properly control injection pressure under the same casting conditions at all times.

In addition, in the present invention, by using an electromagnetic induction pump, it is possible to maintain the hot water level in the hot water supply pipe at an optimal level, and a heating effect is added due to the generation of eddy current due to the electromagnetic induction effect. It is possible to effectively prevent the molten metal from solidifying in the hot water supply pipe during the solidification period after completion of solidification.

Furthermore, when controlling the injection pressure, the pressure change during injection can be set and changed arbitrarily using a microcomputer, and the level of the hot water in the hot water supply pipe can always be maintained at an optimal level. There is no air winding, and productivity is improved by shortening the casting cycle by one step, and defect-free, high-quality castings can be mass-produced.

Although the preferred embodiments of the present invention have been described above, it goes without saying that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the main part configuration and control system of an apparatus for carrying out the casting method according to the present invention, and FIG. 2 is a diagram showing the main part configuration of a conventional low-pressure casting apparatus. 10. Holding furnace 12. , , cover plate 14,
,, Hot water pipe 1G, , Pneumatic supply system 1B
, , , pneumatic source 20. ,, pneumatic control device 22, , fixed die plate 24. ,,lower mold 26,
,,Hot water passage 28. ,, upper mold 30, , mold cavity 32. , , Gas burner 40 , , Excitation coil (electromagnetic induction pump) 42 , , Voltage controller
44. , , hot water level detection sensor 46 , , servo motor

Claims (2)

[Claims] (1) In a casting method in which molten metal in a holding furnace is poured directly into the mold cavity through a hot water supply pipe at low pressure, an electromagnetic induction pump is installed in a part of the hot water supply pipe, and the molten metal level in the holding furnace is A detection sensor is provided movably, and the level of the hot water in the holding furnace is detected by the hot water level detection sensor, and based on this detection signal, the injection pressure setting and the inside of the hot water supply pipe are determined when pouring metal from the hot water pipe into the mold cavity. A casting method characterized in that the excitation voltage of the electromagnetic induction pump is calculated, commanded, and controlled in order to maintain the molten metal at an optimum level. (2) In a casting device configured to pour molten metal in a holding furnace directly into a mold cavity through a hot water supply pipe at low pressure, an electromagnetic induction pump is configured in a position close to the mold cavity of the hot water supply pipe. On the other hand, a hot water level detection sensor for detecting the hot water level is installed in the holding furnace so as to be movable up and down, and the hot water level detection signal is inputted to inject the hot water into the mold cavity from the hot water supply pipe. In order to maintain the injection pressure setting when hot water is heated and the molten metal in the hot water supply pipe at an optimum level, a means is provided for calculating an excitation voltage command for the electromagnetic induction pump, and furthermore, the excitation voltage command obtained by the calculation means is used to calculate the excitation voltage command for the electromagnetic induction pump. A casting device characterized by being provided with a voltage controller for controlling energization of a coil.