Direct-through demagnetizing power supply for steel plates and its demagnetizing method

Abstract

This invention relates to a direct-through demagnetizing power supply and method for steel plates. The method demagnetizes the steel plate by providing an alternating sequence of positive and negative demagnetizing currents that decrease sequentially, achieving higher demagnetizing efficiency than conventional through-type demagnetizing devices. It features easily disassembled demagnetizing clamps, has low requirements for the demagnetizing environment, and can be used for rapid demagnetizing of steel plates in complex environments. This overcomes the shortcomings of through-type demagnetizing devices, such as large footprint, immobility, and low demagnetizing efficiency, and has promising application prospects.

Description

Technical Field

[0001] This invention relates to a demagnetization technique, and more particularly to a direct-through demagnetization power supply for steel plates and a demagnetization method thereof. Background Technology

[0002] Large steel plates are magnetized during smelting, loading and unloading, non-destructive testing using magnetization, or storage in strong magnetic fields, resulting in residual magnetism. When the residual magnetism is below 50 Gs, welding is generally possible. However, when the residual magnetism exceeds 50 Gs, magnetic blow occurs, causing the arc to deviate to one side, resulting in poor fusion on both sides, leading to undercut and incomplete weld penetration, severely impacting weld quality.

[0003] Existing technologies typically employ handheld demagnetizers and through-type demagnetizing devices for demagnetizing steel plates. Handheld demagnetizers have relatively low power, are slow, and have poor demagnetizing effects; they can demagnetize small steel plates but cannot be used for large-area steel plate demagnetization. Through-type demagnetizing devices generate an alternating magnetic field through a demagnetizing coil, in which the steel plate passes through the alternating magnetic field for demagnetization. However, they require a large space, have low demagnetizing efficiency, are time-consuming, and the demagnetizing process is complex and difficult to move, limiting their application scenarios. Summary of the Invention

[0004] To address the existing problems in demagnetization, a direct-through demagnetization power supply for steel plates and its demagnetization method are proposed, which improves demagnetization efficiency and ease of operation.

[0005] The technical solution of the present invention is: a steel plate direct-through demagnetizing power supply, comprising a demagnetizing power supply module, a bus +, a bus -, a demagnetizing cable, a magnetometer, a control unit, a touch screen display, and an auxiliary power supply;

[0006] The demagnetizing power module has its input terminal connected to a three-phase 380V AC power supply, and its output terminal connected to busbar + and busbar -. Busbar + and busbar - are connected to the positive and negative terminals of the demagnetizing clamp via a demagnetizing cable. The demagnetizing power module receives the demagnetizing current command sent by the control unit and converts the input three-phase 380V AC power into a corresponding demagnetizing current. The demagnetizing current demagnetizes the steel plate held by the demagnetizing clamp. A magnetometer is placed at the center of the steel plate to detect the residual magnetism of the steel plate and feeds it back to the control unit. The touch screen receives the demagnetizing setting command and parameters and sends them to the control unit. The auxiliary power supply powers the control power supply and the touch screen.

[0007] Preferably, the demagnetizing power supply module includes a Vienna rectifier unit, an LLC isolated buck unit, and an H-bridge inverter unit connected in sequence;

[0008] The Vienna rectifier unit is used to rectify three-phase 380V AC power into 640V DC power;

[0009] The LLC isolation step-down unit is used to isolate and step down 640V DC power to 40V;

[0010] The H-bridge inverter unit is used to convert 40V DC power into demagnetizing current that follows the demagnetizing command.

[0011] Preferably, several demagnetizing power modules are connected in parallel with equal current, and the parallel output meets the required demagnetizing current.

[0012] Preferably, the bus+ and bus- are evenly distributed at the output terminals of several parallel demagnetizing power modules. The shape of the bus+ and bus- and the impedance of the connecting soft bus with the demagnetizing power modules ensure that the output resistance of each parallel demagnetizing power module is consistent.

[0013] Preferably, the control unit collects the residual magnetism of the steel plate and interacts with the touch screen, receives the demagnetization command from the touch screen, and sends the demagnetization command to the demagnetization power module via CAN communication.

[0014] A demagnetizing method for steel plates using a direct-current demagnetizing power supply, comprising the following specific steps:

[0015] 1) The control unit detects the human-machine interaction information on the touch screen. When it detects the start demagnetization command and the demagnetization current value, it executes step 2).

[0016] 2) The control unit receives the demagnetization information according to step 2), edits the demagnetization pulse sequence command and outputs the corresponding demagnetization current to control the demagnetization power module to output the corresponding demagnetization current; the demagnetization current pulse sequence command alternates between positive and negative, and the amplitude of the demagnetization current decreases by 10% with each alternation until the demagnetization current is reduced to zero, and then executes step 3).

[0017] 3) The control unit reads the residual magnetism of the steel plate detected by the magnetometer. When the residual magnetism is less than the set value, the residual magnetism of the steel plate will not affect the welding and the demagnetization target is achieved, and the demagnetization ends. When the residual magnetism is greater than the set value, the demagnetization target is not achieved, and the process returns to step 2) until the residual magnetism is less than the set value and the demagnetization ends.

[0018] The beneficial effects of this invention are as follows: The direct-through demagnetizing power supply and demagnetizing method for steel plates of this invention demagnetize the steel plate by providing an alternating sequence of positive and negative demagnetizing currents that decrease sequentially. This method has a higher demagnetizing efficiency than conventional through-type demagnetizing devices. The easily disassembled demagnetizing fixture reduces the requirements for the demagnetizing environment, allowing for rapid demagnetizing of steel plates in complex environments. This overcomes the shortcomings of through-type demagnetizing devices, such as large footprint, immobility, and low demagnetizing efficiency, and has good application prospects. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the direct-through demagnetizing power supply structure for the steel plate of the present invention;

[0020] Figure 2 This is a structural block diagram of the demagnetizing power supply module of the present invention;

[0021] Figure 3 This is a flowchart of the demagnetization control process of the present invention;

[0022] Figure 4 This is a diagram of the demagnetizing current pulse sequence of the present invention. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0024] A direct-through demagnetizing power supply and method for steel plates are disclosed. Demagnetization is achieved by directly passing alternating positive and negative demagnetizing pulse currents through the steel plate. The demagnetizing fixture is installed on the steel plate to be demagnetized, allowing for demagnetization anytime, anywhere. The demagnetization time is short, and the demagnetization effect is excellent, making it ideal for steel plate welding sites in shipyards.

[0025] like Figure 1 The schematic diagram of the steel plate direct-through demagnetizing power supply structure is shown. The steel plate direct-through demagnetizing power supply includes a demagnetizing power supply module, bus +, bus -, demagnetizing cable, magnetometer, control unit, touch screen and auxiliary power supply.

[0026] The demagnetizing power module has its input terminal connected to a three-phase 380V AC power supply, and its output terminals connected to busbar + and busbar -. Busbar + and busbar - are connected to the positive and negative terminals of the demagnetizing clamp via a demagnetizing cable. The demagnetizing power module receives demagnetizing current commands from the control unit and converts the input three-phase 380V AC power into a corresponding demagnetizing current, which demagnetizes the steel plate held by the demagnetizing clamp. A magnetometer detects the residual magnetism of the steel plate and feeds it back to the control unit. The touchscreen receives demagnetizing setting commands and parameters and sends them to the control unit. An auxiliary power supply powers both the control power supply and the touchscreen.

[0027] like Figure 2 The block diagram of the demagnetizing power supply module shown is provided. The demagnetizing power supply module includes a Vienna rectifier unit, an LLC isolation buck unit, and an H-bridge inverter unit connected in sequence.

[0028] The Vienna rectifier unit rectifies three-phase 380V AC power into 640V DC power. The input terminal is connected to three-phase 380V AC power, and the output terminal is connected to an LLC isolation step-down unit. It has the advantages of low input harmonics, high power factor, and high efficiency.

[0029] The described LLC isolated step-down unit isolates and steps down 640V DC to 40V. The input terminal is connected to the output terminal of the Vienna rectifier unit, and the output terminal is connected to the H-bridge inverter unit. It adopts LLC resonant soft-switching technology and synchronous rectification technology, and has a primary-side series and secondary-side parallel structure, which has the advantages of low-voltage high-current output capability and high efficiency.

[0030] The H-bridge inverter unit converts 40V DC power into a demagnetizing current that follows the demagnetizing command. The input terminal is connected to the output terminal of the LLC isolation buck unit, and the output terminal is connected to bus + and bus -. The H-bridge inverter can continuously output a positive and negative adjustable demagnetizing current with fast response speed and high steady-state accuracy.

[0031] The demagnetizing power supply module has a parallel current sharing function, with n modules connected in parallel to output the required demagnetizing current.

[0032] The bus+ and bus- collect the outputs of the demagnetizing power modules. The input terminals are connected to the demagnetizing power modules, and the output terminals are connected to the demagnetizing cables. Bus+ and bus- are evenly distributed at the output terminals of several parallel demagnetizing power modules. By reasonably controlling the shape of the bus and the impedance of the connecting flexible bus to the demagnetizing power modules, the output resistance of each parallel demagnetizing power module is basically the same, thereby improving the current sharing effect of the demagnetizing power modules.

[0033] The demagnetizing cable and demagnetizing clamp deliver the demagnetizing current to the steel plate to be demagnetized. The input ends are connected to busbar + and busbar -, and the output ends are fixed to both ends of the steel plate by the demagnetizing clamp. Multiple sets of demagnetizing cables and clamps can be configured, each set capable of withstanding a demagnetizing current of 2000A. The required number of sets is selected according to the maximum demagnetizing current.

[0034] The demagnetizing clamp uses a convenient screw clamping method, supports demagnetization of steel plates up to 100mm thick, and has low contact resistance, reaching less than 100uΩ. The demagnetizing clamps are evenly distributed at both ends of the steel plate, which is beneficial to the uniformity of demagnetization.

[0035] The magnetometer is placed at the center of the steel plate to measure the residual magnetism of the steel plate and transmit the data to the control unit.

[0036] The control unit collects the residual magnetism of the steel plate and interacts with the touch screen, receives the demagnetization command from the touch screen, and sends the demagnetization command to the demagnetization power module via CAN communication.

[0037] The touch screen is the human-computer interaction terminal of this invention. It receives the demagnetization command from the operator and sends it to the control unit. At the same time, it receives the operating data sent by the control unit and displays it.

[0038] The auxiliary power supply converts three-phase 380V AC power into 24V auxiliary power to power the control power supply and the touch screen display.

[0039] like Figure 3 The demagnetization control flowchart shown below details the specific steps:

[0040] Step 1: The control unit detects the human-machine interaction information on the touch screen. When it detects the start demagnetization command and the demagnetization current value, it executes Step 2.

[0041] Step 2: Control the demagnetizing power supply module to output the corresponding demagnetizing current according to the demagnetizing pulse sequence command; the demagnetizing current pulse sequence command alternates between positive and negative, and the amplitude of the demagnetizing current decreases by 10% with each alternation until the demagnetizing current is reduced to zero, then execute step 3;

[0042] Step 3: Read the residual magnetism of the steel plate detected by the magnetometer. When the residual magnetism is less than 30 Gs (adjustable), the residual magnetism of the steel plate will not affect welding, the demagnetization target is achieved, and demagnetization ends. When the residual magnetism is greater than 30 Gs (adjustable), the demagnetization target is not achieved, and Step 2 is executed until the residual magnetism is less than 30 Gs (adjustable), and demagnetization ends.

[0043] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A direct-through demagnetizing power supply for steel plates, characterized in that, Includes a demagnetizing power module, bus +, bus -, demagnetizing cable, magnetometer, control unit, touch display screen, and auxiliary power supply; The demagnetizing power module has an input terminal connected to a three-phase 380V AC power supply and an output terminal connected to busbar + and busbar -. Busbar + and busbar - are connected to the positive and negative terminals of the demagnetizing clamp via a demagnetizing cable. The demagnetizing power module receives the demagnetizing current command sent by the control unit and converts the input three-phase 380V AC power into a corresponding demagnetizing current. The demagnetizing current is used to demagnetize the steel plate held by the demagnetizing clamp. A magnetometer is placed at the center of the steel plate to detect the residual magnetism of the steel plate and feed it back to the control unit. The touch screen receives demagnetization setting instructions and parameters and sends them to the control unit. An auxiliary power supply powers the control power supply and the touch screen. The demagnetization power module includes a Vienna rectifier unit, an LLC isolation step-down unit and an H-bridge inverter unit connected in sequence. The Vienna rectifier unit is used to rectify three-phase 380V AC power into 640V DC power; The LLC isolation step-down unit is used to isolate and step down 640V DC power to 40V; The H-bridge inverter unit is used to convert 40V DC power into demagnetizing current that follows the demagnetizing command.

2. The direct-through demagnetizing power supply for steel plates according to claim 1, characterized in that, Several demagnetizing power modules are connected in parallel to share current, and their parallel output meets the required demagnetizing current.

3. The direct-through demagnetizing power supply for steel plates according to claim 2, characterized in that, The bus+ and bus- are evenly distributed at the output terminals of several parallel demagnetizing power modules. The shape of the bus+ and bus- and the impedance of the connecting soft bus with the demagnetizing power modules ensure that the output resistance of each parallel demagnetizing power module is consistent.

4. The direct-through demagnetizing power supply for steel plates according to claim 1, characterized in that, The control unit collects the residual magnetism of the steel plate and interacts with the touch screen, receives the demagnetization command from the touch screen, and sends the demagnetization command to the demagnetization power module via CAN communication.

5. A demagnetizing method for steel plates using a direct-current demagnetizing power supply, characterized in that, Demagnetization is performed using the direct-through demagnetizing power supply for the steel plate as described in claim 1, and the specific steps are as follows: 1) The control unit detects the human-machine interaction information on the touch screen. When it detects the start demagnetization command and the demagnetization current value, it executes step 2). 2) The control unit receives the demagnetization information according to step 1), edits the demagnetization pulse sequence command and outputs the corresponding demagnetization current to control the demagnetization power supply module; the demagnetization current pulse sequence command alternates between positive and negative, and the amplitude of the demagnetization current decreases by 10% with each alternation until the demagnetization current is reduced to zero, and then executes step 3). 3) The control unit reads the residual magnetism of the steel plate detected by the magnetometer. When the residual magnetism is less than the set value, the residual magnetism of the steel plate will not affect the welding and the demagnetization target is achieved, and the demagnetization ends. When the residual magnetism is greater than the set value, the demagnetization target is not achieved, and the unit returns to step 2) until the residual magnetism is less than the set value and the demagnetization ends.

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