A heating device for the throat of a riser pipe in a low-pressure casting machine

Abstract

This utility model relates to a heating device for the throat of a riser pipe in a low-pressure casting machine. It includes a crucible containing molten aluminum, with a riser pipe inserted into the crucible and extending into the molten aluminum. An induction heater is fitted at the throat of the riser pipe, connected to a heating unit. A steel flange is located in the middle of the induction heater, fitting snugly against the outer wall of the throat of the riser pipe. This utility model achieves integrated control through a heating unit, using electromagnetic induction to precisely control the temperature of the riser pipe throat. The steel flange in the middle of the induction heater allows heat to be conducted to the riser pipe and then to the molten aluminum as the flange heats up, effectively solving the problem of aluminum solidification.

Description

Technical Field

[0001] This utility model relates to a throat heating device for a riser pipe, and more particularly to a throat heating device for a riser pipe used in a low-pressure casting machine, belonging to the technical field of low-pressure casting. Background Technology

[0002] In the casting process, molten aluminum rises from the crucible through a riser pipe into the mold cavity. The throat of the riser pipe, as a critical channel for the flow of molten aluminum, is prone to significant temperature drops due to its large heat dissipation area and long residence time of the molten aluminum. Therefore, heating the throat of the riser pipe is necessary. Furthermore, when the temperature of the molten aluminum falls below the liquidus line, a solidified layer forms, causing flow channel blockage, affecting casting continuity, and potentially leading to inclusion defects in the casting due to solidified layer detachment. Frequent cleaning of solidified material also increases equipment maintenance costs and downtime. Existing technologies, such as traditional external heating methods (e.g., resistance heating), suffer from low heating efficiency, uneven temperature distribution, and susceptibility to damage, failing to meet the requirements of high-precision casting processes.

[0003] Therefore, developing an efficient and safe heating device for the throat of a riser pipe is of great significance. This invention is thus derived. Utility Model Content

[0004] To address the aforementioned technical problems in the prior art, the purpose of this utility model is to provide a heating device for the throat of a riser pipe in a low-pressure casting machine. This device is integrated and controlled by a heating host, and achieves precise temperature control of the throat of the riser pipe through the principle of electromagnetic induction. A steel flange is designed in the middle of the induction heater. After the temperature of the steel flange rises, the heat can be conducted to the riser pipe and then to the molten aluminum, effectively solving the problem of molten aluminum solidification.

[0005] To achieve the above objectives, this utility model is implemented through the following technical solution:

[0006] A heating device for the throat of a riser pipe in a low-pressure casting machine includes a crucible containing molten aluminum and a riser pipe inserted into the crucible. The riser pipe extends into the molten aluminum. An induction heater is fitted at the throat of the riser pipe. The induction heater is connected to a heating host and a steel flange is provided in the middle of the induction heater. The steel flange is fitted to the outer wall of the throat of the riser pipe.

[0007] The steel flange is ring-shaped.

[0008] The induction heater is an induction coil, and the induction coil and the steel flange are coupled in a non-contact manner.

[0009] The induction coil is made of hollow copper tube and is covered with a high-temperature resistant insulating layer.

[0010] The heating host is an integrated heating host, which adopts a PLC control system to monitor and adjust the heating power, temperature and time parameters in real time.

[0011] The integrated heating host is equipped with a human-machine interface and supports process parameter preset and data storage functions.

[0012] The integrated heating host has a built-in over-temperature protection module and an over-current protection module.

[0013] The PLC control system collects temperature data in real time through thermocouples embedded in the throat of the riser pipe and dynamically adjusts the current frequency of the induction coil to keep the deviation between the heating temperature and the set value within the allowable range.

[0014] The integrated heating host is connected to the main control system of the low-pressure casting machine, receives process signals during the filling stage / holding stage, and starts the heating program only during the holding stage. During the filling stage, it automatically reduces the heating power to maintain the temperature.

[0015] The over-temperature protection module is equipped with a dual judgment mechanism. When the throat temperature exceeds the set threshold or the temperature rise rate of the steel flange is greater than 10℃ / s, the power supply is immediately cut off and an audible and visual alarm is triggered.

[0016] The beneficial effects of this utility model are as follows:

[0017] This invention relates to a heating device for the throat of a riser pipe in a low-pressure casting machine. It integrates control through a heating main unit and utilizes electromagnetic induction to achieve precise temperature control at the throat. An induction heater acts on a steel flange at the throat, generating electromagnetic eddy currents that raise the flange temperature. Heat is then transferred from the flange through the riser pipe to the molten aluminum, solving the problem of aluminum solidification at the throat and meeting the requirements of high aluminum temperature or long holding times in casting production. Furthermore, this invention innovatively introduces casting stage identification technology. By analyzing the real-time pressure curve of the low-pressure casting machine, it intelligently determines the filling and holding stages, activating full-power heating only during the holding stage when the risk of aluminum stagnation is highest, achieving an optimal balance between energy consumption and heating efficiency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of this utility model;

[0019] Figure 2 This is a cross-sectional structural diagram of the present invention;

[0020] Among them, 1 is the heating host, 2 is the riser pipe, 3 is the induction heater, 4 is the steel flange, 5 is the crucible, and 6 is the aluminum liquid. Detailed Implementation

[0021] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0022] like Figure 1 and 2 As shown, this utility model is mainly used in low-pressure casting machines. A riser pipe 2 is installed inside the crucible 5, and the riser pipe 2 is inserted into the molten aluminum 6 inside the crucible 5. An induction heater 3 is fitted at the throat of the riser pipe 2. The induction heater 3 is connected to a heating unit 1, and a steel flange 4 is provided in the middle of the induction heater 3. The steel flange 4 is annular and fits tightly against the outer wall of the throat of the riser pipe 3, transferring heat to the molten aluminum through heat conduction. The induction heater 3 is an induction coil, made of hollow copper tubing, and covered with a high-temperature resistant insulating layer.

[0023] Furthermore, the induction coil and the steel flange 4 in this invention are designed with a non-contact coupling to avoid mechanical wear.

[0024] Furthermore, the heating host 1 in this invention is an integrated heating host, employing a PLC control system. The PLC control system collects temperature data in real time via thermocouples embedded at the throat of the riser pipe, dynamically adjusting the current frequency of the induction coil to keep the deviation between the heating temperature and the set value within an allowable range. It can monitor and adjust heating power, temperature, and time parameters in real time. It is equipped with a human-machine interface, supporting process parameter presets and data storage functions. It has built-in over-temperature protection and over-current protection modules. The over-temperature protection module has a dual judgment mechanism: when the throat temperature exceeds the set threshold or the temperature rise rate of the steel flange is >10℃ / s, it immediately cuts off the power and triggers an audible and visual alarm to ensure safe operation of the equipment. Moreover, the integrated heating host is communicatively connected to the main control system of the low-pressure casting machine, receiving process signals during the filling / holding stages. The heating program is only activated during the holding stage, and the heating power is automatically reduced to a temperature maintenance mode during the filling stage.

[0025] In this invention, the heating host 1 establishes communication with the main control system of the low-pressure casting machine to acquire the pressurization curve and stage signals of the casting machine in real time. During the filling stage, the heating power is automatically reduced to maintain only the base temperature; after entering the holding pressure stage, the power is increased for compensatory heating. The specific control relationships, process parameter preset and storage methods, and over-temperature and over-current protection modules of the PLC control system can all adopt modules or methods commonly used in the field, and are not the protection content of this invention, so they will not be described in detail here.

[0026] The heating method at the throat of the riser tube 2 in this invention is as follows:

[0027] The induction heater 3 in the heating host 1 is fitted at the throat of the riser pipe 2. The induction heater 3 is an induction coil made of hollow copper tube, covered with a high-temperature resistant insulation layer, and has a steel flange 4 at its center as the induction heating element. During heating, the heating host 1 supplies high-frequency alternating current (frequency range above 100kHz) to the induction heater 3. An alternating magnetic field is generated around the induction heater 3. Under the action of the magnetic field, the steel flange 4 generates eddy current effect, and the violent movement of electrons inside is converted into heat energy, causing the temperature of the steel flange 4 to rise rapidly. The heat is conducted to the aluminum liquid through the pipe wall of the riser pipe 2, maintaining the temperature of the aluminum liquid at the throat of the riser pipe 3 within the process requirements.

[0028] This invention employs a medium-frequency heating induction coil with a frequency range of 500Hz-10kHz to inductively heat the steel flange 4 at the throat of the riser pipe 2. The heating of the steel flange 4 prevents the temperature at the throat of the riser pipe 2 from dropping. The induction coil does not require water cooling, ensuring that the risk of explosion due to water pipe rupture is avoided in low-pressure aluminum alloy casting processes. Furthermore, the induction coil uses a low-voltage, high-current heating method, with a safe voltage. In the low-pressure casting environment, all equipment is made of conductive metal, preventing electric shock accidents caused by the rupture of the induction coil due to high temperatures.

[0029] Furthermore, the rapid temperature drop at the throat leads to defects such as porosity and air bubbles in the casting, and blockage of the riser pipe 2, preventing production. The addition of a medium-frequency induction coil allows for rapid heating of the throat. Combined with the characteristics of low-pressure casting, the time for the riser pipe 2 to fill with molten aluminum is very short in each production cycle. Therefore, the throat heating device does not need to be constantly activated; heating is only required during the pressure holding stage. Traditional resistance coils or gas heating cannot achieve rapid, continuous heating, have short lifespans, and require high investment costs. This new medium-frequency heating system avoids these problems, offering rapid heating, good stability, long service life, and guaranteed safety.

[0030] The above embodiments are only used to explain the inventive concept of this utility model, and are not intended to limit the protection of this utility model. Any non-substantial modifications made to this utility model using this concept should fall within the protection scope of this utility model.

Claims

1. A heating device for the throat of a riser pipe in a low-pressure casting machine, comprising a crucible containing molten aluminum, and a riser pipe inserted into the crucible, the riser pipe extending into the molten aluminum, characterized in that: An induction heater is fitted at the throat of the riser pipe. The induction heater is connected to a heating host, and a steel flange is provided in the middle of the induction heater. The steel flange is fitted to the outer wall of the throat of the riser pipe.

2. The riser throat heating device for a low-pressure casting machine as described in claim 1, characterized in that: The steel flange is ring-shaped.

3. The riser throat heating device for a low-pressure casting machine as described in claim 1, characterized in that: The induction heater is an induction coil, and the induction coil and the steel flange are coupled in a non-contact manner.

4. The riser throat heating device for a low-pressure casting machine as described in claim 3, characterized in that: The induction coil is made of hollow copper tube and is covered with a high-temperature resistant insulating layer.

5. The riser throat heating device for a low-pressure casting machine as described in claim 1, characterized in that: The heating host is an integrated heating host, which adopts a PLC control system to monitor and adjust the heating power, temperature and time parameters in real time.

6. The riser throat heating device for a low-pressure casting machine as described in claim 5, characterized in that: The integrated heating host is equipped with a human-machine interface and supports process parameter preset and data storage functions.

7. The riser throat heating device for a low-pressure casting machine as described in claim 5, characterized in that: The integrated heating host has a built-in over-temperature protection module and an over-current protection module.

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