High-precision intermediate frequency heater control cabinet

Abstract

The invention provides a high-precision intermediate-frequency heater control cabinet which comprises a high-precision intermediate-frequency heating protector, and the power output end of the high-precision intermediate-frequency heating protector is connected with the power input end of an intermediate-frequency heater. The high-precision medium-frequency heating protector comprises a voltage detection module, a current detection module and at least two temperature detection modules. The voltage detection module and the current detection module are used for detecting voltage and current values between the high-precision medium-frequency heating protector and the medium-frequency heater; the temperature detection module is used for detecting the temperature of a heated workpiece; the intermediate frequency heater comprises a current detection module and a temperature detection module; the current detection module and the temperature detection module are used for detecting the temperature and the current value of a heated workpiece; the working current of the intermediate frequency heater and the temperature of the heated workpiece can be monitored and adjusted in real time, and the problem that the measurement accuracy of a single temperature probe of the intermediate frequency heater is not high is solved.

Description

Technical Field

[0001] The invention relates to the technical field of electrical automation equipment, and in particular to a high-precision medium-frequency heater control cabinet. Background Art

[0002] The high-precision medium frequency heater control cabinet has dual redundant safety settings. Through two sets of safety self-test devices, the real-time voltage, temperature and current values ​​of the medium frequency heater during operation can be accurately monitored. The operator can reasonably calculate the heating curve and adjust it in real time according to the material characteristics, specifications and dimensions of the heated workpiece, and cut off the power supply in time when the current, temperature and other parameters exceed the set range to achieve the purpose of protecting the medium frequency heater.

[0003] Generally speaking, due to the high power, large voltage and current fluctuations of medium frequency heaters, and the inaccurate measurement of a single temperature probe of medium frequency heaters, medium frequency heaters have control hysteresis and equipment overload problems during use, which can easily lead to inaccurate local temperature sampling of large heated workpieces and equipment damage caused by excessive local temperature. Therefore, in the process of using medium frequency heaters, it is necessary to adopt a three-dimensional multi-module multi-channel temperature control and redundant protection solution to achieve reasonable local or overall heating of large irregular multi-material mixed workpieces. Summary of the invention

[0004] The present invention aims to at least solve the technical problems existing in the prior art, and in particular innovatively proposes a high-precision medium-frequency heater control cabinet.

[0005] In order to achieve the above-mentioned object of the present invention, the present invention provides a high-precision medium frequency heater control cabinet, comprising a high-precision medium frequency heating protector, wherein the power output end of the high-precision medium frequency heating protector is connected to the power input end of the medium frequency heater;

[0006] The high-precision intermediate frequency heating protector includes a voltage detection module, a current detection module and at least two temperature detection modules; the voltage detection module and the current detection module are used to detect the voltage and current values ​​between the high-precision intermediate frequency heating protector and the intermediate frequency heater; the temperature detection module is used to detect the temperature of the heated workpiece;

[0007] The intermediate frequency heater includes a current detection module and a temperature detection module; the current detection module, the temperature detection module and the current detection module are used to detect the temperature and current value of the heated workpiece;

[0008] Among them, the voltage detection module includes a voltage digital display, the current detection module includes a current digital display, and the temperature detection module includes a temperature digital display.

[0009] The temperature detection module of the high-precision medium frequency heating protector is used to detect the heated workpiece, and the temperature detection module of the medium frequency heater is used to detect the temperature output by the power element of the heater itself.

[0010] The current detection module of the high-precision medium-frequency heating protector is used for the output current of the three-phase power supply, and the current detection module of the medium-frequency heater is used for the output current of the medium-frequency heater.

[0011] Preferably, the high-precision medium-frequency heating protector comprises:

[0012] The three-phase power lines U, V, and W are respectively connected in series with the voltage digital display, air switch ZK1, current transformer, AC contactor KM, and medium frequency heater; among them, the current transformer is connected with the current digital display.

[0013] Preferably, the high-precision medium-frequency heating protector further includes:

[0014] There are several parallel-connected circuits between the power V-phase line and the neutral line of the three-phase power line, including the secondary control circuit of the AC contactor, the power supply circuit of the voltage digital display, the power supply circuit of the current digital display, the power supply circuit of the temperature digital display, the control circuit of the working indicator light of the control cabinet, and the output control circuit of the current alarm switch;

[0015] The AC contactor secondary control circuit includes: a first end of a normally closed stop button switch SB1 is connected to a power supply V-phase line of a three-phase power line, a second end of the normally closed stop button switch SB1 is connected to a first end of a normally open start button switch SB2 and a first end of a normally open contact switch of the AC contactor KM, a second end of the start button switch SB2 and a second end of the normally open contact switch of the AC contactor KM are connected to a first end of a normally open contact switch of a temperature digital display T1, a second end of the normally open contact switch of the temperature digital display T1 is connected to a first end of a normally open contact switch of the temperature digital display T2, a second end of the normally open contact switch of the temperature digital display T2 is connected to a first end of a normally closed contact switch of an AC relay KA2, a second end of the normally closed contact switch of the AC relay KA2 is connected to a first end of a coil of the AC contactor KM and a first end of a coil of the AC relay KA1; a second end of the coil of the AC contactor KM and a second end of the coil of the AC relay KA1 are connected to a neutral line;

[0016] The voltage digital display power supply circuit comprises: a power supply V phase line of a three-phase power supply line is connected to a first end of the voltage digital display V, and a second end of the voltage digital display V is connected to a neutral line;

[0017] The current digital display power supply circuit comprises: a power supply phase V line of a three-phase power line is connected to a first end of a current transformer, a second end of the current transformer is connected to a first end of a current digital display A, and a second end of the current digital display A is connected to a neutral line;

[0018] The voltage transformer reduces the high voltage to a safe level, and then the voltage digital display measures the reduced voltage and displays it in digital form. This combination ensures the safety and accuracy of the measurement. The same is true for the current transformer.

[0019] The power supply circuit of the temperature digital display comprises: the power supply V phase line of the three-phase power line is connected to the first end of the coil of the temperature digital display T1; the second end of the coil of the temperature digital display T1 is connected to the neutral line;

[0020] The power supply V phase line of the three-phase power line is connected to the first end of the coil of the temperature digital display instrument T2; the second end of the coil of the temperature digital display instrument T2 is connected to the neutral line;

[0021] The control circuit of the working indicator light of the control cabinet includes: the power supply V phase line of the three-phase power line is connected to the first end of the normally closed contact switch of the AC relay KA1, the second end of the normally closed contact switch of the AC relay KA1 is connected to the first end of the working indicator light HL1, and the second end of the working indicator light HL1 is connected to the neutral line; the working indicator light HL1 is used to indicate abnormal working;

[0022] The power V phase line of the three-phase power line is connected to the first end of the normally open contact switch of the AC relay KA1, the second end of the normally open contact switch of the AC relay KA1 is connected to the first end of the working indicator light HL2, and the second end of the working indicator light HL2 is connected to the neutral line; the working indicator light HL2 is used for normal working indication;

[0023] The current alarm switch output control circuit includes: the power supply V phase line of the three-phase power line is respectively connected to the first end of the first current digital display switch I1, the first end of the second current digital display switch I2, and the first end of the third current digital display switch I3; the second end of the second current digital display switch I1, the second end of the second current digital display switch I2, and the second end of the third current digital display switch I3 are all connected to the first end of the coil of the AC relay KA2; the second end of the coil of the AC relay KA2 is connected to the neutral line;

[0024] Among them, the first current digital display switch, the second current digital display switch, and the third current digital display switch are normally open switches. The first current digital display switch, the second current digital display switch, and the third current digital display switch are used in conjunction with current transformers CT1, CT2, and CT3 to measure the current of the three-phase power line. If the current I1 of the first-phase power line is detected to be higher than the safety value, the first current digital display switch is closed; if the current I2 of the second-phase power line is detected to be higher than the safety value, the second current digital display switch is closed; if the current I3 of the third-phase power line is detected to be higher than the safety value, the third current digital display switch is closed. When any of the first current digital display switch, the second current digital display switch, and the third current digital display switch is closed, the coil of the AC relay KA2 is energized, the normally closed contact switch of the AC relay KA2 is disconnected, and the medium frequency heater control cabinet stops running.

[0025] The current transformers CT1, CT2 and CT3 are connected to the upper connector of the AC contactor. When the AC contactor coil is powered on, the main contacts of the AC contactor are closed and the power is output to the medium frequency heater.

[0026] Preferably, the workflow of the high-precision medium frequency heater control cabinet includes:

[0027] S1, the high-precision medium-frequency heating protector performs power-on self-test: the voltage U of the three-phase electricity is monitored in real time by using a voltage digital display, the working current I of each power cable is collected by using a current digital display through a current transformer, and the initial working temperature T of the heated workpiece is monitored in real time by using a temperature digital display; the temperature digital display obtains the temperature T through a temperature probe, specifically by placing the temperature probe at the position where the workpiece temperature is highest; for workpieces that require precise processing, a hole is drilled on the heated workpiece and heat transfer oil is introduced, and then the probe is placed in the heat transfer oil to achieve precise temperature sampling, wherein the current, voltage, and temperature values ​​are displayed in real time on the control panel;

[0028] S2. When the power-on self-test is completed, the startup steps begin: When the detected voltage U, current I, and initial working temperature T are all within the set normal value range, press the start button switch SB2. At this time, the secondary control circuit is turned on: the AC contactor KM is energized. Place the temperature probe of the high-precision medium-frequency heating protector and the temperature probe of the medium-frequency heater into the standard temperature thermal conductivity pool; check whether these temperature probes can accurately and quickly detect the temperature to ensure that the equipment is operating normally. If the probes are working normally, sample the probe temperature of the high-precision medium-frequency heating protector and the probe temperature of the medium-frequency heater; at this time, the normally open contact switch of the temperature digital display T1 and the normally open contact switch of the temperature digital display T2 are closed; then based on the sampled data, set the parameters of the external heating function of the medium-frequency heater, including the output power of the medium-frequency heater, specifically set the temperature value and current value of the heated workpiece on the medium-frequency heater;

[0029] S3, operation steps: according to the shape specifications of the heated workpiece, measure the distance L from the workpiece surface to the center of the heated area, drill a hole to obtain a medium frequency heater, and insert the medium frequency heater probe into the bottom of the drilled hole; then select and drill holes in the heating area whose depth from the workpiece surface is less than the distance L and / or holes in the non-heating area as holes for high-precision medium frequency heating protectors, and insert the high-precision medium frequency heating protector probe into the bottom of the hole;

[0030] When the heated workpiece is a regular column, select a suitable point at the heated part of the workpiece and drill a hole. Measure the distance L from the workpiece surface to the center of the heated area. The depth of the three holes increases in sequence. The depth of the first hole is 1 / 3L from the workpiece surface, the depth of the second hole is 2 / 3L from the workpiece surface, and the third hole is drilled to the center of the heated area. Insert the medium frequency heater probe into the deep hole drilled, and the two temperature probes of the high-precision medium frequency heating protector are inserted into the first two shallow holes in sequence, and the temperature probe of the medium frequency heater is inserted into the third hole.

[0031] When the AC contactor KM is closed and power is supplied to the outside, the power of the high-precision medium-frequency heating protector is output to the medium-frequency heater. Press the start button of the medium-frequency heater and adjust the power knob. At this time, the workpiece is heated and the output current of the medium-frequency heater is observed. For metal workpieces of specific materials that are heated for the first time, experimental heating experiments can be carried out to collect data and establish a heating curve calculation formula. The specific method is to count the time required for the heated workpiece to be heated to the rated temperature and the temperature collected in real time by the temperature probe, calculate the time-temperature heating curve, and adjust the output power. When the medium-frequency heater probe detects that the temperature at the deepest part of the workpiece has reached the preset value, the equipment stops heating. When the temperature probe of the high-precision medium-frequency heating protector detects that the temperature of the external hole of the heated workpiece has also risen to the set value, the temperature protection is immediately started to prevent the medium-frequency heater from overheating and damaging the workpiece due to failure of the medium-frequency heater temperature probe, thereby achieving safe heating of the workpiece.

[0032] The installation position of the temperature probe is determined according to the size and area of ​​the heated workpiece, and the drilling position and depth of the temperature probe of the high-precision intermediate frequency heating protector and the intermediate frequency heater temperature probe are determined, so as to achieve three-dimensional high-precision local and overall heating of special workpieces with irregular volumes and mixed materials. The temperature probe is used for the temperature detection module.

[0033] Preferably, during the operation step, during the operation step, the current digital display and voltage digital display of the high-precision medium frequency heating protector continuously detect the voltage and current of the power supply; and monitor the temperature of the heated workpiece in real time. When the temperature value or current value of the heated workpiece is greater than the set value, the relevant protection device of the high-precision medium frequency heater control cabinet immediately acts to cut off the power output to prevent the heated workpiece from being damaged by excessive temperature, thereby achieving the purpose of protecting the medium frequency heater. Specifically, when the circuit current exceeds the set value range, the current alarm switch output control circuit is turned on, and the secondary control circuit of the AC contactor is disconnected, so that the AC contactor KM is disconnected; when the temperature of the heated workpiece exceeds the set value range, the secondary control circuit of the AC contactor is disconnected, so that the AC contactor KM is disconnected.

[0034] Preferably, during the operation step, the workpiece to be heated is heated by the medium frequency heater, and there are two heating methods;

[0035] Method 1: When the volume of the heated workpiece is greater than or equal to 0.5 cubic meters, directly wrap the heating wire of the medium frequency heater around the heated part of the heated workpiece;

[0036] Method 2: When the volume of the heated workpiece is less than 0.5 cubic meters, the heating wire of the medium frequency heater is respectively wound around a dummy load and the heated part of the heated workpiece, and the dummy load is a metal object.

[0037] When the heated workpiece is small, the second method is used to ensure sufficient inductance and reach a cointegration equilibrium point by adjusting the parameters, thereby ensuring the stability, efficiency and controllability of the heating process.

[0038] Preferably, the process of power-on self-test and operation steps also includes:

[0039] The voltage digital display monitors the working voltage. When the voltage is undervoltage, overvoltage or phase loss, the voltage digital display will display it on the panel in real time.

[0040] The current digital display monitors the current of three three-phase power lines. When the current of any one of the three power lines exceeds the set value, the current digital display switch changes from the normally open state to the normally closed state, causing the coil of the AC relay KA2 to be energized, thereby disconnecting the power supply of the secondary control circuit of the AC contactor. The coil of the AC contactor KM loses power, causing the contact switch of the AC contactor KM to be disconnected, and finally causing the AC contactor KM to disconnect the power supply, thereby ensuring the equipment safety of the medium frequency heater. It can realize multi-probe and multi-channel temperature cross-comparison, and realize multi-point three-dimensional detection of workpieces with huge specifications and irregular sizes, ensuring that large irregular workpieces with mixed materials can achieve overall uniform heating, and avoid extrusion deformation damage caused by local overheating.

[0041] The temperature digital display monitors the heated workpiece in real time. When the temperature of the heated workpiece exceeds the upper limit of the set value, the temperature digital display will change the temperature alarm switch (the temperature alarm switch is the normally open contact switch of the temperature digital display T1 and the temperature alarm switch is the normally open contact switch of the temperature digital display T2) from the normally closed state to the normally open state. The temperature digital display monitors the temperature of the heated workpiece, causing the secondary power supply circuit of the AC contactor to be disconnected, and then the coil of KM loses power, thereby disconnecting the main power supply;

[0042] The voltage, current and temperature detection modules of the high-precision medium frequency heater control cabinet continuously monitor these parameters to ensure that they are within the safe range. Once any parameter is detected to exceed the set safety value, the system will immediately cut off the current output to protect the medium frequency heater itself and the heated workpiece.

[0043] Preferably, the starting step comprises:

[0044] After the power-on self-test, the power supply voltage displayed by the voltage digital display is within the normal range, the switches of the three current digital displays are in the normally open state, the normally closed point of the AC relay KA2 remains in the closed state, and the switches of the two temperature digital displays are in the normally closed state; at this time, the normally closed switch of the AC relay KA2 and the normally closed switch of the temperature digital display constitute a secondary control circuit for controlling the on and off of the AC relay, and there is no breakpoint except the start button. When the start button is pressed, the secondary control circuit is turned on, and then the normally open contact switch of the AC contactor KM is closed, and the normally closed switch of the AC relay KA2 is connected to the power supply.

[0045] Preferably, it also includes: if the temperature detection module of the medium frequency heater detects that the temperature is higher than a set temperature threshold, or the current detected by the current detection module is higher than a set current threshold, the medium frequency heater cuts off the current output.

[0046] In summary, due to the adoption of the above technical solution, the present invention can achieve three-dimensional high-precision heating of large irregular, mixed workpieces of various metal materials, and is equipped with temperature monitoring, voltage monitoring, leakage protection, current protection, manual start, and manual shutdown functions, which can effectively prevent the medium frequency heater from being damaged by excessive power, leakage, overcurrent, undervoltage, and overtemperature. The main advantages are as follows:

[0047] (1) A high-precision medium-frequency heating protector with multiple temperature probes is designed. Compared with the medium-frequency heater that can only detect the center of the workpiece heating area, the present invention can detect the local temperature of the workpiece, the non-heating area, and the temperature of the non-center of the heating area; in this way, the temperature distribution of the workpiece can be fully detected, and the temperature changes of each area during the heating process can be accurately grasped to ensure the accuracy and controllability of the heating process. By detecting the local temperature of the workpiece, the temperature changes of each area during the heating process can be monitored in real time to ensure that the heating process is more accurate. This helps to avoid quality problems such as deformation and cracking of the workpiece caused by uneven heating. Temperature detection of the non-heating area can timely detect and prevent the diffusion of heat to the non-heating area, ensuring that the heating process is more concentrated and efficient. In addition, potential overheating risks can be discovered in time to avoid excessive heating of the medium-frequency heater and damage to the workpiece due to failure of the medium-frequency heater temperature probe, thereby achieving safe heating of the workpiece.

[0048] (2) The present invention can monitor and adjust the working current of the medium frequency heater and the temperature of the heated workpiece in real time, solving the problem of low measurement accuracy of a single temperature probe of the medium frequency heater, and is helpful for safe and reasonable three-dimensional heating of large-sized, irregularly shaped workpieces with mixed parts of various metal materials. In addition, it also solves the problem that the circuit protection system used by the medium frequency heater itself reacts slowly when the current is overloaded and the temperature is too high, which easily burns the components of the medium frequency heater.

[0049] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0051] Figure 1 It is a schematic diagram of a main control circuit according to an embodiment disclosed in the present invention.

[0052] Figure 2 It is a schematic diagram of a secondary control loop according to an embodiment disclosed in the present invention.

[0053] Figure 3 It is a schematic diagram of the working principle of an embodiment disclosed in the present invention.

[0054] Figure symbols: L1: power supply U phase; L2: power supply V phase; L3: power supply W phase; V: voltage digital display; A: current digital display; T1: temperature digital display; T2: temperature digital display; ZK1: air protection switch; KM: AC contactor; KA1: AC relay; KA2: AC relay; SB1: stop button; SB2: start button; U(t): input power supply voltage; I(t): circuit real-time current; T1(t): real-time temperature of the heated workpiece; T2(t): the temperature of the heated workpiece detected by temperature detection probe 1; T3(t): the temperature of the heated workpiece detected by temperature detection probe 2. DETAILED DESCRIPTION

[0055] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0056] The present invention proposes a high-precision medium frequency heater control cabinet, which belongs to the technical field of electrical automation equipment. The control cabinet comprises a medium frequency heater, a cabinet body and a voltage digital display, a current digital display, a temperature digital display and buttons on the front of the cabinet body. The cabinet body contains a current transformer, an AC contactor, an AC relay and an air switch. This control cabinet monitors the voltage in real time through the voltage digital display, and the current digital display collects the real-time current of the three-phase AC through the current transformer. It adopts a multi-module multi-channel mode, and innovatively realizes the multi-point temperature stereoscopic detection of large-sized irregular workpieces and the directional heating function of specific areas of the workpiece. The temperature digital display monitors the temperature of the heated workpiece in real time. By monitoring the voltage on the panel of the digital display, the temperature of the heated workpiece and the upper and lower limits of the current are collected in real time. The alarm output switches on the current digital display and the temperature digital display are connected in series and then connected to the secondary control circuit. Only when the current and temperature are within the set range, the start button is pressed, the secondary control circuit will be turned on, and the AC contactor can be attracted, so as to connect the power supply to the intermediate frequency heater. After the intermediate frequency heater power supply is connected, the temperature value is set, and the start button is pressed to start heating the workpiece. According to the heating curve of different positions of the workpiece, the power output can be adjusted by the knob. When the temperature probes at each point detect that the temperature of the heated workpiece reaches the preset value or when the output current of the heater is too large, the intermediate frequency heater stops working.

[0057] The present invention uses a voltage digital display to directly collect the main circuit voltage and display it on the voltage digital display panel. The temperature digital display uses a temperature probe to directly contact the surface of the heated workpiece or insert the probe into the inside of the heated workpiece to accurately obtain the temperature. The alarm switches of two temperature digital displays are connected in series in the secondary control circuit of KM to prevent the failure of the temperature protection function caused by the damage of a single temperature probe. The power supply cable is passed through the current transformer coil to indirectly measure the real-time current value of the three-phase electricity.

[0058] like Figure 1 As shown in the main control circuit diagram, when the voltage digital display directly collects voltage from the connector on the air switch ZK1, it enters the voltage digital display after passing through the fuse, and the voltage value is displayed on the digital display panel. The three power cables pass through the current transformers CT1, CT2, and CT3 respectively. These current transformers are not only connected to the current digital display to display current data, but their outputs are also connected to the input of the AC contactor. When the coil of the AC contactor is energized, its main contact will close, so that the power can be output to the medium frequency heater.

[0059] like Figure 2 As shown, in the secondary control circuit, it is divided into the secondary control circuit of the AC contactor, the power supply circuit of the voltage digital display, the power supply circuit of the current digital display, the power supply circuit of the temperature digital display, the control circuit of the working indicator light of the control cabinet, and the output control circuit of the current alarm switch. Among them, the secondary control circuit of the AC contactor is composed of the stop button switch, the start button switch, the two temperature digital display alarm normally closed switches, the KA2 normally closed contact switch, and the coil of the KM AC contactor in series, wherein the normally open contact switch of the AC contactor KM is connected in parallel with the SB2 start button switch. When there is no current overcurrent alarm and no temperature alarm, the three switches T1, T2, and KA2 are all in the closed state. At this time, the start button is pressed, the coil of the AC contactor KM is energized, and the coil is closed, so that the main contact of the main contactor of the AC contactor KM is closed. When there is a temperature alarm and a current alarm, this control secondary control circuit is disconnected to achieve the protection purpose. In the power supply circuit of the voltage digital display, the live wire and the neutral wire are respectively connected to the power interface of the voltage digital display to realize the power supply of the equipment. In the power supply circuit of the current digital display, connect the live wire and the neutral wire to the power interface of the current digital display to realize the power supply of the equipment. In the power supply circuit of the temperature digital display, connect the live wire and the neutral wire to the power interface of the temperature digital display to realize the power supply of the equipment. In the control circuit of the working indicator light of the control cabinet, the red light is connected in series with the normally closed contact switch of KA1 and then connected to the power supply, and the green light is connected in series with the normally open contact switch of KA1. When the control cabinet is not working, the red light is on and the green light is off. When the start button is pressed, if KA1 is energized to attract the coil, the red light will be off and the green light will be on.

[0060] like Figure 3As shown in the control flow diagram of the high-precision medium-frequency heater control cabinet, the first step is to connect the external power supply to the high-precision medium-frequency heater control cabinet, and the power-on self-test step is used to detect the voltage and current flowing through the medium-frequency heater. Monitor the temperature of the heated workpiece at the end and display the value on the control panel in real time. Startup step, when the voltage, current, and temperature are within the set normal value range, press the start button, the secondary control circuit is turned on, the AC contactor KM coil is energized, and the power is output to the medium-frequency heater. The operation steps are as follows: when the AC contactor is closed and supplies power to the outside, the voltage and current of the power supply are continuously detected, and the temperature of the heated workpiece is monitored in real time. When the circuit current and the temperature of the heated workpiece exceed the set value range, the control module alarms and outputs, and the secondary power supply circuit of the AC contactor KM is cut off, thereby disconnecting the AC contactor to achieve the purpose of protecting the medium frequency heater. At the same time, the medium frequency heater equipment body also has a set of current, temperature detection and protection functions, which can cut off the current output when the temperature of the heated workpiece is too high or the current load is too large, solving the problem that the single temperature probe of the medium frequency heater has low measurement accuracy, and the circuit protection system used by the medium frequency heater itself reacts slowly when the current is overloaded and the temperature is too high, which makes it easy to burn out the components of the medium frequency heater.

[0061] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A high-precision medium frequency heater control cabinet, characterized in that: It includes a high-precision medium-frequency heating protector, wherein the power output end of the high-precision medium-frequency heating protector is connected to the power input end of the medium-frequency heater; The high-precision intermediate frequency heating protector includes a voltage detection module, a current detection module and at least two temperature detection modules; the voltage detection module and the current detection module are used to detect the voltage and current values ​​between the high-precision intermediate frequency heating protector and the intermediate frequency heater; the temperature detection module is used to detect the temperature of the heated workpiece; The intermediate frequency heater includes a current detection module and a temperature detection module; the current detection module, the temperature detection module and the current detection module are used to detect the temperature and current value of the heated workpiece; Among them, the voltage detection module includes a voltage digital display, the current detection module includes a current digital display, and the temperature detection module includes a temperature digital display.

2. The high-precision medium frequency heater control cabinet according to claim 1 is characterized in that: The high-precision medium-frequency heating protector comprises: The three-phase power lines U, V, and W are respectively connected in series with the voltage digital display, air switch ZK1, current transformer, AC contactor KM, and medium frequency heater; among them, the current transformer is connected with the current digital display.

3. The high-precision medium frequency heater control cabinet according to claim 1 is characterized in that: The high-precision medium-frequency heating protector also includes: There are several parallel-connected circuits between the power V-phase line and the neutral line of the three-phase power line, including the secondary control circuit of the AC contactor, the power supply circuit of the voltage digital display, the power supply circuit of the current digital display, the power supply circuit of the temperature digital display, the control circuit of the working indicator light of the control cabinet, and the output control circuit of the current alarm switch; The AC contactor secondary control circuit includes: a first end of a normally closed stop button switch SB1 is connected to a power supply V-phase line of a three-phase power line, a second end of the normally closed stop button switch SB1 is connected to a first end of a normally open start button switch SB2 and a first end of a normally open contact switch of the AC contactor KM, a second end of the start button switch SB2 and a second end of the normally open contact switch of the AC contactor KM are connected to a first end of a normally open contact switch of a temperature digital display T1, a second end of the normally open contact switch of the temperature digital display T1 is connected to a first end of a normally open contact switch of the temperature digital display T2, a second end of the normally open contact switch of the temperature digital display T2 is connected to a first end of a normally closed contact switch of an AC relay KA2, a second end of the normally closed contact switch of the AC relay KA2 is connected to a first end of a coil of the AC contactor KM and a first end of a coil of the AC relay KA1; a second end of the coil of the AC contactor KM and a second end of the coil of the AC relay KA1 are connected to a neutral line; The voltage digital display power supply circuit comprises: a power supply V phase line of a three-phase power supply line is connected to a first end of the voltage digital display V, and a second end of the voltage digital display V is connected to a neutral line; The current digital display power supply circuit comprises: a power supply phase V line of a three-phase power line is connected to a first end of a current transformer, a second end of the current transformer is connected to a first end of a current digital display A, and a second end of the current digital display A is connected to a neutral line; The power supply circuit of the temperature digital display comprises: the power supply V phase line of the three-phase power line is connected to the first end of the coil of the temperature digital display T1; the second end of the coil of the temperature digital display T1 is connected to the neutral line; The power supply V phase line of the three-phase power line is connected to the first end of the coil of the temperature digital display instrument T2; the second end of the coil of the temperature digital display instrument T2 is connected to the neutral line; The control circuit of the working indicator light of the control cabinet includes: the power supply V phase line of the three-phase power line is connected to the first end of the normally closed contact switch of the AC relay KA1, the second end of the normally closed contact switch of the AC relay KA1 is connected to the first end of the working indicator light HL1, and the second end of the working indicator light HL1 is connected to the neutral line; The power V phase line of the three-phase power line is connected to the first end of the normally open contact switch of the AC relay KA1, the second end of the normally open contact switch of the AC relay KA1 is connected to the first end of the working indicator light HL2, and the second end of the working indicator light HL2 is connected to the neutral line; The current alarm switch output control circuit includes: the power supply V phase line of the three-phase power line is respectively connected to the first end of the first current digital display switch I1, the first end of the second current digital display switch I2, and the first end of the third current digital display switch I3; the second end of the second current digital display switch I1, the second end of the second current digital display switch I2, and the second end of the third current digital display switch I3 are all connected to the first end of the coil of the AC relay KA2; the second end of the coil of the AC relay KA2 is connected to the neutral line.

4. The high-precision medium frequency heater control cabinet according to claim 1 is characterized in that: The working process of the high-precision medium frequency heater control cabinet includes: S1, the high-precision medium-frequency heating protector performs power-on self-test: the voltage U of the three-phase electricity is monitored in real time by using a voltage digital display, the working current I of each power cable is collected by using a current digital display through a current transformer, and the initial working temperature T of the heated workpiece is monitored in real time by using a temperature digital display; S2, when the power-on self-test is completed, start the startup steps: when the detected voltage U, current I, and initial working temperature T are all within the set normal value range, press the start button switch SB2, and put the temperature probe of the high-precision intermediate frequency heating protector and the temperature probe of the intermediate frequency heater into the standard temperature thermal conductivity pool; if the probe works normally, sample the probe temperature of the high-precision intermediate frequency heating protector and the probe temperature of the intermediate frequency heater; at this time, the normally open contact switch of the temperature digital display T1 and the normally open contact switch of the temperature digital display T2 are closed; then based on the sampled data, set the parameters of the external heating function of the intermediate frequency heater; S3, operation steps: according to the shape specifications of the heated workpiece, measure the distance L from the workpiece surface to the center of the heated area, drill a hole to obtain the medium frequency heater, and insert the medium frequency heater probe into the bottom of the drilled hole; then select and drill holes in the heating area whose depth from the workpiece surface is less than the distance L and / or holes in the non-heating area as holes for the high-precision medium frequency heating protector, and insert the high-precision medium frequency heating protector probe into the bottom of the hole; then, the power supply of the high-precision medium frequency heating protector is output to the medium frequency heater, press the start button of the medium frequency heater, and adjust the power knob. At this time, the workpiece is heated, and the output current of the medium frequency heater is observed.

5. The working method of the high-precision medium frequency heater control cabinet according to claim 4 is characterized in that: During the operation steps, the current digital display and voltage digital display of the high-precision medium frequency heating protector continuously detect the voltage and current of the power supply; and monitor the temperature of the heated workpiece in real time. When the temperature value or current value of the heated workpiece is greater than the set value, the relevant protection device of the high-precision medium frequency heater control cabinet will immediately act to cut off the power output to prevent the heated workpiece from being damaged by excessive temperature, thereby achieving the purpose of protecting the medium frequency heater.

6. The high-precision medium frequency heater control cabinet operating method according to claim 4 is characterized in that: During the operation step, the workpiece is heated by the medium frequency heater. There are two heating methods: Method 1: When the volume of the heated workpiece is greater than or equal to 0.5 cubic meters, directly wrap the heating wire of the medium frequency heater around the heated part of the heated workpiece; Method 2: When the volume of the heated workpiece is less than 0.5 cubic meters, the heating wire of the medium frequency heater is respectively wound around a dummy load and the heated part of the heated workpiece, and the dummy load is a metal object.

7. The working method of the high-precision medium frequency heater control cabinet according to claim 4 is characterized in that: The power-on self-test and operation steps also include: The voltage digital display monitors the working voltage. When the voltage is undervoltage, overvoltage or phase loss, the voltage digital display will display it on the panel in real time. The current digital display monitors the current of three three-phase power lines. When the current of any one of the three power lines exceeds the set value, the current digital display switch changes from the normally open state to the normally closed state, causing the coil of the AC relay KA2 to be attracted, thereby disconnecting the power supply of the secondary control circuit of the AC contactor. The coil of the AC contactor KM loses power, causing the contact switch of the AC contactor KM to be disconnected, and finally causing the AC contactor KM to disconnect the power supply; The temperature digital display monitors the heated workpiece in real time. When the temperature of the heated workpiece exceeds the upper limit of the set value, the temperature digital display will change the temperature alarm switch from the normally closed state to the normally open state. The temperature digital display monitors the temperature of the heated workpiece, causing the secondary power supply circuit of the AC contactor to be disconnected, and then the coil of KM loses power, thereby disconnecting the main power supply.

8. The working method of the high-precision medium-frequency heater control cabinet according to claim 4 is characterized in that: The startup steps include: After the power-on self-test, the power supply voltage displayed by the voltage digital display is within the normal range, the switches of the three current digital displays are in the normally open state, the normally closed point of the AC relay KA2 remains in the closed state, and the switches of the two temperature digital displays are in the normally closed state; at this time, the normally closed switch of the AC relay KA2 and the normally closed switch of the temperature digital display constitute a secondary control circuit for controlling the on and off of the AC relay, and there is no breakpoint except the start button. When the start button is pressed, the secondary control circuit is turned on, and then the normally open contact switch of the AC contactor KM is closed, and the normally closed switch of the AC relay KA2 is connected to the power supply.

9. The working method of the high-precision medium-frequency heater control cabinet according to claim 4 is characterized in that: Also includes: If the temperature detection module of the intermediate frequency heater detects that the temperature is higher than the set temperature threshold, or the current detected by the current detection module is higher than the set current threshold, the intermediate frequency heater cuts off the current output.

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