Rigid fireproof cable online frequency conversion annealing device

Abstract

The invention discloses an online variable frequency annealing device for rigid fireproof cables, belonging to the technical field of cable annealing. An online annealing device with a variable frequency function for heating a copper skin and a copper core respectively is proposed. The technical scheme is as follows: the online variable frequency annealing device for rigid fireproof cables comprises: a shell, an induction heating module and a cooling module; the shell is provided with the induction heating module and the cooling module, and the cable passes through the induction heating module and the cooling module in sequence; the induction heating module comprises: a heating coil and a variable frequency control circuit; the variable frequency control circuit provides a variable frequency electromagnetic field for the heating coil, realizes variable frequency electromagnetic heating for the cable, heats the copper skin and the copper core, and realizes the purpose of uniform annealing effect.

Description

Technical Field

[0001] The invention discloses an online frequency conversion annealing device for rigid fireproof cables, belonging to the technical field of cable annealing. Background Art

[0002] During the rolling process of rigid fireproof cables, work hardening will make subsequent rolling impossible, so the cables need to be annealed online to ensure continuous rolling of the cables. The cable production line is tens or even hundreds of meters long, so traditional resistance furnaces cannot complete online annealing. Induction heating devices can complete the annealing process. Rigid fireproof cables are three-layer composite structures, from the outside to the inside, they are the outer copper skin, magnesium oxide powder and copper core. Due to the skin effect, fixed-frequency induction heaters often cause the outer copper skin to reach the softening temperature during annealing, while the temperature of the inner copper core is still very low, making it difficult to achieve overall annealing of the cable. Summary of the invention

[0003] In order to solve the above technical problems, the present invention proposes an online annealing device with a frequency conversion function for heating the copper skin and the copper core respectively.

[0004] In order to achieve the above technical objectives, the technical solution provided by the present invention is:

[0005] The rigid fireproof cable online variable frequency annealing device comprises: a shell, an induction heating module and a cooling module; the shell is provided with the induction heating module and the cooling module, and the cable is heated by the heating coil;

[0006] The induction heating module comprises: a heating coil and a frequency conversion control circuit; the heating coil is fixed on the housing, the frequency conversion control circuit is fixed in the housing, and the frequency conversion control circuit is electrically connected to the heating coil;

[0007] The frequency conversion control circuit is as follows: the positive pole of the power supply D is connected in parallel to one end of the inductor L1 and one end of the inductor L2, the other end of the inductor L1 is connected in parallel to one end of the heating coil, one end of the heating capacitor group and the D pole of the field effect tube Q1, the other end of the inductor L2 is connected in parallel to the other end of the heating coil, the other end of the heating capacitor group and the D pole of the field effect tube Q2, the S pole of the field effect tube Q1 and the S pole of the field effect tube Q2 are grounded, the G pole of the field effect tube Q1 is connected in series with a resistor R1 and then connected to the positive pole of the power supply D, a diode D2 is connected in series between the G pole of the field effect tube Q1 and the D pole of the field effect tube Q2, a diode D1 is connected in series between the G pole of the field effect tube Q2 and the D pole of the field effect tube Q1, the G pole of the field effect tube Q2 is connected in series with a resistor R2 and then connected to the positive pole of the power supply D, the heating capacitor group includes at least one capacitor C3, and several capacitors of the heating capacitor group are arranged in parallel.

[0008] A control switch S is connected in series to each of C1 and C2 of the heating capacitor group.

[0009] The time when the field effect transistor Q1 reaches its turn-on voltage Vtn1 is different from the time when the field effect transistor Q2 reaches its turn-on voltage Vtn1.

[0010] The shell is a square box with a through hole running through the entire box. A ring-shaped heating coil is fixed to one side of the shell wall with the through hole. The heating coil is a hollow copper tube, and the two pins of the heating coil are co-centering with the through hole.

[0011] A cooling module is fixed in the outer shell, and the cooling module includes: a fan, a cold water pump and a circulating water pipe. The fan is fixed near the other side of the outer shell wall where the heating coil is arranged. The fan cools the frequency conversion control circuit board. The circulating water pipe is arranged along the inner side of the box wall and is divided into three sections. One end of the first section of the circulating water pipe is connected to a pin of the heating coil, and the other end is connected to a water source. The inlet of the cold water pump is connected to the water source through the second section of the circulating water pipe, and the outlet of the cold water pump is connected to another pin of the heating coil through the third section of the circulating water pipe.

[0012] A main power switch is arranged on the positive output end of the power source D, and the main power switch is embedded on the wall of the outer shell.

[0013] A plurality of control switches S are embedded on the wall of the outer casing.

[0014] The S pole of the field effect tube Q1 and the ground terminal are connected in parallel to a voltage stabilizing diode D3 and a resistor R3; the S pole of the field effect tube Q2 and the ground terminal are connected in parallel to a voltage stabilizing diode D4 and a resistor R4.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention adopts an LC oscillation circuit in combination with a field effect transistor to form a heating current for the heating coil, and then changes the size of the LC oscillation circuit capacitor to change the frequency of the electromagnetic field change of the heating coil, thereby achieving electromagnetic field frequency conversion for cable work, and then changing the heating effect of the cable copper skin and inner copper core, and combined with different combinations of heating capacitors, the heating temperature of the cable copper skin and copper core can be uniform, thereby improving the cable annealing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the present invention.

[0018] Figure 2 This is the frequency conversion control circuit diagram of the present invention.

[0019] In the figure: 1 is a housing, 21 is a heating coil, 22 is a frequency conversion control circuit, 31 is a fan, 32 is a cold water pump, and 33 is a circulating water pipe. DETAILED DESCRIPTION

[0020] In order to further understand the present invention, the following is described in detail with reference to the accompanying drawings and embodiments:

[0021] like Figure 1 and Figure 2 As shown: the rigid fireproof cable online variable frequency annealing device of the present invention comprises: a housing 1, an induction heating module and a cooling module; the housing 1 is provided with an induction heating module and a cooling module, and the cable is heated by a heating coil;

[0022] The induction heating module includes: a heating coil 21 and a frequency conversion control circuit 22; the heating coil 21 is fixed on the housing 1, the frequency conversion control circuit 22 is fixed in the housing 1, and the frequency conversion control circuit 22 is electrically connected to the heating coil 21;

[0023] The frequency conversion control circuit 22 is as follows: the positive pole of the power supply D is connected in parallel to one end of the inductor L1 and one end of the inductor L2, the other end of the inductor L1 is connected in parallel to one end of the heating coil 21, one end of the heating capacitor group and the D pole of the field effect tube Q1, the other end of the inductor L2 is connected in parallel to the other end of the heating coil 21, the other end of the heating capacitor group and the D pole of the field effect tube Q2, the S pole of the field effect tube Q1 and the S pole of the field effect tube Q2 are grounded, the G pole of the field effect tube Q1 is connected in series with the resistor R1 and then connected to the positive pole of the power supply D, the G pole of the field effect tube Q1 and the D pole of the field effect tube Q2 are connected in series with the diode D2, the G pole of the field effect tube Q2 and the D pole of the field effect tube Q1 are connected in series with the diode D1, the G pole of the field effect tube Q2 is connected in series with the resistor R2 and then connected to the positive pole of the power supply D, the heating capacitor group includes at least one capacitor C3, and several capacitors of the heating capacitor group are arranged in parallel.

[0024] For example: the resistance value of the resistor R1 is equal to the resistance value of the resistor R2, and the heating capacitor group is provided with three parallel capacitors C1, C2 and C3, wherein the capacitor C1 is connected in series with the switch 1, and the capacitor C2 is connected in series with the switch 2. At this time, the field effect tube Q1 first reaches the turn-on voltage Vth1, the S pole of the field effect tube Q1 is connected with the D pole of the field effect tube Q1, and the D pole potential of the field effect tube Q1 is pulled down, close to the ground terminal potential, and the G pole of the field effect tube Q2 is at a high potential, and the diode D1 connects the G pole of the field effect tube Q2 with the S pole of the field effect tube Q1, and the G pole voltage of the field effect tube Q2 is reduced, and the field effect tube Q2 is completely cut off. The power supply D charges the capacitor C connected to the circuit through the inductor L2. As time goes by, the D pole potential of the field effect tube Q2 reaches a peak value, and the heating coil and the capacitor C connected to the circuit form a parallel resonant circuit. The D-pole potential of the field effect tube Q2 will begin to drop. When the voltage drops to zero, the diode D2 is turned on, discharging the G-pole of the field effect tube Q1, causing the field effect tube Q1 to turn off from on, and the D-pole voltage of the field effect tube Q1 begins to rise. The field effect tube Q2 is turned on, and the D-pole potential of the field effect tube Q2 is pulled down to the ground voltage, and the field effect tube Q1 is completely turned off. The power supply D charges the corresponding capacitor C through the inductor L1. As time goes by, the D-pole potential of the field effect tube Q1 reaches the peak value, and the heating coil and the corresponding capacitor C form a parallel resonant circuit. The D-pole potential of the field effect tube Q1 will begin to drop. When it drops to zero, the diode D1 is turned on, discharging the G-pole of the field effect tube Q2, causing the field effect tube Q2 to turn off from on, and the D-pole voltage of the field effect tube Q2 begins to rise and returns to the initial state. This reciprocating cycle forms a continuous sinusoidal current oscillation state. When heating the cable, eddy currents are formed inside the copper skin and the copper core. During the heating process, the number of capacitors C connected to the circuit is changed multiple times to change the heating frequency, and different frequency combinations are used to eventually make the copper skin and copper core reach the heating temperature.

[0025] A control switch S is connected in series to each of C1 and C2 of the heating capacitor group.

[0026] The time when the field effect transistor Q1 reaches its turn-on voltage Vtn1 is different from the time when the field effect transistor Q2 reaches its turn-on voltage Vtn1.

[0027] The shell 1 is a square box, and a through hole is provided on the shell 1 that runs through the entire box. A ring-shaped heating coil 21 is fixed to one side of the box wall of the shell 1 with the through hole. The heating coil 21 is a hollow copper tube, and the two pins of the heating coil 21 are co-centering with the through hole.

[0028] A cooling module is fixed in the outer shell 1, and the cooling module includes: a fan 31, a cold water pump 32 and a circulating water pipe 33. The fan 31 is fixed near the other side of the box wall of the outer shell 1 where the heating coil 21 is arranged. The fan 31 cools the frequency conversion control circuit board. The circulating water pipe is arranged along the inner side of the box wall and is divided into three sections. One end of the first section of the circulating water pipe is connected to a pin of the heating coil 21, and the other end is connected to a water source. The inlet of the cold water pump 32 is connected to the water source through the second section of the circulating water pipe, and the outlet of the cold water pump is connected to another pin of the heating coil 21 through the third section of the circulating water pipe.

[0029] A main power switch is provided on the positive output end of the power source D, and the main power switch is embedded on the wall of the housing 1.

[0030] A plurality of control switches S are embedded on the wall of the housing 1 .

[0031] The S pole of the field effect tube Q1 and the ground terminal are connected in parallel to a voltage stabilizing diode D3 and a resistor R3; the S pole of the field effect tube Q2 and the ground terminal are connected in parallel to a voltage stabilizing diode D4 and a resistor R4.

[0032] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Those familiar with the technology may modify or improve the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. Rigid fireproof cable online frequency conversion annealing device, characterized in that: include: Housing (1), induction heating module and cooling module; The housing (1) is provided with an induction heating module and a cooling module, and the cable is heated by a heating coil; The induction heating module comprises: a heating coil (21) and a frequency conversion control circuit (22); the heating coil (21) is fixed on the housing (1), the frequency conversion control circuit (22) is fixed in the housing (1), and the frequency conversion control circuit (22) is electrically connected to the heating coil (21); The frequency conversion control circuit (22) comprises: a positive electrode of a power source D is connected in parallel to one end of an inductor L1 and one end of an inductor L2; the other end of the inductor L1 is connected in parallel to one end of a heating coil (21), one end of a heating capacitor group and a D electrode of a field effect tube Q1; the other end of the inductor L2 is connected in parallel to the other end of the heating coil (21), the other end of the heating capacitor group and a D electrode of a field effect tube Q2; the S electrode of the field effect tube Q1 and the S electrode of the field effect tube Q2 are grounded; the G electrode of the field effect tube Q1 is connected in series with a resistor R1 and then connected to the positive electrode of the power source D; a diode D2 is connected in series between the G electrode of the field effect tube Q1 and the D electrode of the field effect tube Q2; a diode D1 is connected in series between the G electrode of the field effect tube Q2 and the D electrode of the field effect tube Q1; the G electrode of the field effect tube Q2 is connected in series with a resistor R2 and then connected to the positive electrode of the power source D; the heating capacitor group comprises a plurality of capacitors C3; and the plurality of capacitors C3 of the heating capacitor group are arranged in parallel; A main power switch is provided at the positive output end of the power source D, and the main power switch is embedded in the wall of the housing (1); The S pole of the field effect tube Q1 and the ground terminal are connected in parallel to a voltage stabilizing diode D3 and a resistor R3; the S pole of the field effect tube Q2 and the ground terminal are connected in parallel to a voltage stabilizing diode D4 and a resistor R4.

2. According to claim 1, the online variable frequency annealing device for rigid fireproof cables is characterized by: The heating capacitor group includes a capacitor C1 and a capacitor C2, and each of the capacitors C1 and C2 is connected in series with a control switch S.

3. According to claim 2, the online variable frequency annealing device for rigid fireproof cables is characterized by: The time when the field effect transistor Q1 reaches its turn-on voltage Vtn1 is different from the time when the field effect transistor Q2 reaches its turn-on voltage Vtn1.

4. According to claim 3, the online variable frequency annealing device for rigid fireproof cables is characterized by: The shell (1) is a square box, and a through hole is provided on the shell (1) that penetrates the entire box. A ring-shaped heating coil (21) is fixed to one side of the box wall of the shell (1) having the through hole. The heating coil is a hollow copper tube, and two pins of the heating coil (21) are co-centering with the through hole.

5. According to claim 4, the online variable frequency annealing device for rigid fireproof cables is characterized by: A cooling module is fixed inside the housing (1), and the cooling module comprises: a fan (31), a cold water pump (32) and a circulating water pipe (33). The fan (31) is fixed near the other side of the housing (1) wall where the heating coil (21) is arranged, and the fan (31) cools the frequency conversion control circuit board. The circulating water pipe is arranged along the inner side of the housing wall and is divided into three sections. One end of the first section of the circulating water pipe is connected to a pin of the heating coil (21), and the other end is connected to a water source. The inlet of the cold water pump (32) is connected to the water source through the second section of the circulating water pipe, and the outlet of the cold water pump is connected to another pin of the heating coil (21) through the third section of the circulating water pipe.

Images