CN220820256U

CN220820256U - Hot cutting knife

Info

Publication number: CN220820256U
Application number: CN202321795040.0U
Authority: CN
Inventors: 杨诚昊
Original assignee: Zhejiang Prade Electric Co ltd
Current assignee: Zhejiang Prade Electric Co ltd
Priority date: 2023-07-07
Filing date: 2023-07-07
Publication date: 2024-04-19
Anticipated expiration: 2033-07-07

Abstract

The utility model discloses a hot cutting knife, which belongs to the technical field of heating cutting equipment, and solves the problems that the prior art can only be applicable to alternating current and has lower fault tolerance rate; the load circuit comprises two conductive terminals arranged in the machine body, and the two conductive terminals are respectively and electrically connected with the cutter in a contact way to form a loop and generate load current to heat the cutter; the input end of the detection circuit is electrically connected with the load circuit and generates a detection signal according to the load current, and the output end of the detection circuit is electrically connected with the signal input end of the control circuit and outputs the detection signal to the control circuit; the signal output end of the control circuit is electrically connected with the load circuit and adjusts the power output by the load circuit to be matched with the cutter size according to the detection signal so as to heat the cutter. The process for detecting the cutter size is not limited to alternating current, direct current products can be suitable, detection is not needed at the moment of power-on, and the fault tolerance is higher.

Description

Hot cutting knife

Technical Field

The utility model relates to the technical field of heating cutting equipment, in particular to a hot cutting knife.

Background

Thermal cutting is a separation method for melting or burning materials by utilizing concentrated heat energy, and is widely applied to industries such as metal material blanking, processing of parts, waste and scrap disintegration and the like. Based on the hot cutting technology, a hot cutting knife is developed, the working power of the machine corresponding to the difference of the size of the hot cutting knife is also different, when the hot cutting knife is used, the machine with the corresponding power needs to be replaced according to the different cutter sizes, otherwise, the cutter is damaged or the requirements cannot be met, for example: the use of a hot cutter with a power of 200W of 30mm can cause deformation or even blowing of the cutter; the 200W power uses a 200mm hot cutting knife to cause insufficient heat, and the use requirement is not met.

In the prior art, chinese patent publication No. CN110470204A discloses a method for automatically identifying a knife handle by induction detection of a power coil, which comprises the following steps: s1, determining the sizes of different tool shanks and the frequency and time of the optimal heating current of the corresponding power coil, and writing and storing a corresponding control program according to a determined result; s2, starting heating by a hot charging machine; s3, detecting a waveform peak value of alternating current at the moment of energizing the power coil; s4, automatically judging the size of the heated knife handle according to the waveform peak value; and S5, according to the judged size of the heated knife handle, calling the optimal heating frequency and time corresponding to the control power coil stored in the corresponding control program to heat the knife handle. In the prior art, electromagnetic heating of the cutter handle is realized through the power coil, when the size of the cutter handle is judged, the detection is based on the waveform peak value of alternating current generated at the moment of electrifying the power coil, the detection can only be performed by using the alternating current, and the use limitation is large. In the prior art, the purpose of heating is to heat the cutter for hot loading and taking, only the cutter handle is heated, and the heating process is short instead of heating the whole cutter, so that the waveform peak value of alternating current needs to be detected at the moment of power coil electrifying, the condition of overhigh temperature occurs after a long time, the requirement on detection signals is high, and the fault tolerance rate is low.

Disclosure of utility model

The utility model aims to provide a hot cutting knife, which solves the problems that the prior art can only be applied to alternating current and has lower fault tolerance, the process of detecting the size of the cutting knife is not limited to alternating current, direct current products can also be applied, detection is not needed at the moment of power-on, and the fault tolerance is higher.

In order to achieve the above purpose, the utility model adopts the following technical scheme: the hot cutting knife comprises a machine body and a knife, wherein the front end of the machine body is provided with a clamping head, the knife is detachably connected with the clamping head, and the machine body is provided with a load circuit, a detection circuit and a control circuit;

The load circuit comprises two conductive terminals arranged in the machine body, and the two conductive terminals are respectively and electrically connected with the cutter in a contact way to form a loop and generate load current to heat the cutter;

The input end of the detection circuit is electrically connected with the load circuit and generates a detection signal according to the load current, and the output end of the detection circuit is electrically connected with the signal input end of the control circuit and outputs the detection signal to the control circuit;

The signal output end of the control circuit is electrically connected with the load circuit and adjusts the power output by the load circuit to be matched with the cutter size according to the detection signal so as to heat the cutter.

After the technical scheme is adopted, the utility model has the following advantages: because the equivalent resistance values of the cutters with different sizes are different, the sizes of load currents generated after the cutters with different sizes are connected into the load circuit are also different, so that based on the load currents with different sizes, the detection circuit can generate corresponding different detection signals, the power suitable for the current cutter can be determined based on the detection signals, the power output by the load circuit is adjusted, and the cutters are normally heated, so that the hot cutters are self-adaptively heated for the cutters with different sizes, the conditions that the cutters are overheated or the heating speed is too slow are effectively prevented, the heating efficiency of the cutters is ensured, and the service life of the cutters is prolonged. Because the cutter is always connected in the load circuit, the cutter can be preheated firstly, the same power can be output when the cutter is preheated aiming at cutters with different sizes, the cutter is preheated by lower power in the preheating process, and the condition of overheating can not occur in a certain time, so that a detection signal can be obtained aiming at the load current in a period of time, the detection is not needed at the instant of electrifying, the detection fault tolerance rate can be improved, and the detection accuracy can be improved by detecting the load current at a plurality of time points. Because the cutter is directly connected into the load circuit, the load circuit is not limited by alternating current and direct current, so that the cutter can be suitable for alternating current and direct current products. And the cutter is connected into the load circuit and electrically connected with the machine body to heat the cutter, the electric connection heating directly converts electric energy into heat energy to heat the cutter, and the cutter is heated uniformly. The electric connection heating can be also suitable for cutters made of various conductive materials, including metal or nonmetal cutters, and the application range is wide. Meanwhile, the cutter is detachably connected to the machine body, when cutters of different sizes are used, only the cutters are required to be detached and replaced, the flexibility is high, the interchangeability is good, and the overhaul is convenient.

Further, the load circuit comprises a first transformer, and a secondary of the first transformer and the cutter form a loop. After the cutter is inserted into the machine body of the hot cutting knife, a loop is formed between the secondary of the first transformer and the cutter to generate load current, and the characteristics of low-voltage large current and lifting voltage can be output by utilizing the secondary of the first transformer, so that the cutter with smaller size can be suitable for the cutter, and the size range of the cutter suitable for products is widened.

Further, the detection circuit is connected with the primary side of the first transformer, so as to generate a detection signal according to the load current. After the secondary of the first transformer is connected with the cutter, the sizes of the cutters inserted into the machine body are different, and the currents generated by the primary of the first transformer are different, so that the detection circuit is connected with the primary of the first transformer, the detection circuit can generate a detection signal according to the load current generated by the load circuit and output the detection signal to the control circuit, and the control circuit can adjust the load circuit to output power matched with the cutter in size according to the detection signal so as to heat the cutter.

Further, the load circuit comprises a forward push-pull circuit, the forward push-pull circuit is connected with the primary side of a first transformer, the primary side of the first transformer comprises a first winding and a second winding, the forward push-pull circuit comprises a first switching tube and a second switching tube, the grid electrode of the first switching tube is connected with the first signal output end of the control circuit, the source electrode of the first switching tube is connected with one end of the second winding, the drain electrode of the first switching tube is connected with the positive electrode of the power supply and one end of the first winding, and the output of the second winding is determined according to the on-off state of the first switching tube; the grid electrode of the second switching tube is connected with a second signal output end of the control circuit, the source electrode of the first switching tube is connected with the other end of the second winding and the negative electrode of the power supply, the drain electrode of the first switching tube is connected with the other end of the first winding, and the output of the first winding is determined according to the on-off state of the second switching tube. The two signal output ends of the control circuit are respectively and correspondingly connected with the first switch tube and the second switch of the forward push-pull circuit, and different signals are output at different signal output ends to control the first switch tube Q1 or the second switch tube Q2 to be conducted/cut off, so that the primary of the first transformer is controlled to realize alternate output, and the stable low-voltage high current output by the secondary of the first transformer is favorably met.

Further, the load circuit comprises a second transformer, the primary of the second transformer is connected with the cutter in series, the secondary of the second transformer is connected with the detection circuit, and the detection circuit induces load current through the second transformer, so that a detection signal is generated according to the load current. After the second transformer is connected with the cutter and the detection circuit, the cutter inserted into the machine body is different in size, the primary current flowing through the second transformer is also different, and the secondary induced current of the second transformer is correspondingly changed, so that the detection circuit is connected with the secondary of the second transformer, and can also generate a detection signal according to the load current and output the detection signal to the control circuit.

Further, the detection circuit comprises a detection element, the current value and/or the voltage value of the detection element change along with the load current, and the detection signal is the current value and/or the voltage value of the detection element. When the machine body is inserted into cutters with different sizes, load currents with different sizes are generated, and the current value and/or the voltage value of the detection element in the detection circuit are different, namely, the detection signals corresponding to the load currents with different sizes are also different, so that the control circuit can determine the output power suitable for the current cutter based on the detection signals, and accordingly, the power of the output matched cutter is adjusted to heat the cutter.

Further, the detection circuit further comprises a rectifying element and a filtering circuit, the rectifying element is electrically connected between the secondary of the second transformer and the filtering circuit, and the filtering circuit is electrically connected with the detection element. By connecting the rectifying element, the alternating current can be converted into direct current, which is more beneficial to the processing of a control circuit and the stable output of the output power which is more matched with the size of the cutter. In order to prevent unstable current in the detection circuit, a filter circuit is connected into the detection circuit, and the filter circuit can generate electromotive force so as to resist the change of the current, ensure the stability of the detection circuit, and be favorable for the detection circuit to accurately receive the current value and/or the voltage value of the detection element and accurately output a detection signal to the control circuit.

Further, the rectifying element comprises a diode, wherein the anode of the diode is connected with the secondary of the second transformer, and the cathode of the diode is connected with the filter circuit. The cost of using the diode is low.

Further, the rectifying element comprises a rectifying bridge, a first end of the rectifying bridge is connected with a secondary end of the second transformer, a second end of the rectifying bridge is connected with the filter circuit, a third end of the rectifying bridge is connected with the secondary end of the second transformer, and a fourth end of the rectifying bridge is grounded. The rectifier bridge can carry out full-wave bridge rectification to obtain stable direct-current voltage, so that the control circuit can acquire more stable detection signals and accurately judge the detection signals.

Further, the control circuit comprises a control chip of the corresponding relation between preset current or voltage data and the power required by the heating tool, and the control chip compares the power required by the heating tool corresponding to the preset current or voltage data after receiving the detection signal, and/or comprises a control chip with a function, and the control chip calculates the power required by the heating tool according to the detection signal and the function. The control chip can directly obtain the corresponding power according to the comparison of the detection signals through the corresponding relation between the preset current or voltage data and the power required by the heating tool, so that the power required by the corresponding heating tool can be rapidly output, the calculated amount can be reduced, the control circuit can rapidly respond, the heating efficiency is improved, and the operation load of the control chip is reduced; and calculating and outputting the power required by the heating cutter according to a control chip with a preset function, so that the power output by the load circuit is more accurate and is more matched with the size of the cutter.

Drawings

The utility model is further described below with reference to the accompanying drawings:

FIG. 1 is a schematic diagram of a thermal cutter according to a first embodiment of the present utility model;

FIG. 2 is a circuit diagram of a thermal cutting blade according to a first embodiment of the present utility model;

FIG. 3 is a circuit diagram of a thermal cutting blade according to a first embodiment of the present utility model;

fig. 4 is a circuit diagram of a thermal cutting blade according to a second embodiment of the present utility model.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model, and it is apparent that the described embodiments are only some embodiments of the present utility model, not all embodiments.

The terms "first," "second," and the like in the description and in the claims, if any, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order, and do not necessarily indicate a "first" even if a "second" is used before a certain feature. It should be understood that in the present utility model, "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. It should be understood that in the present utility model, "plurality" means two or more. "and/or" is merely an association relationship describing an association object, meaning that three relationships may exist, for example, X and/or Y may represent: x alone, X and Y together, and Y alone. The character "/" generally indicates that the context-dependent object is an "or" relationship. "comprising X, Y and Z", "comprising X, Y, Z" means that all three of X, Y, Z comprise, "comprising X, Y or Z" means that one of X, Y, Z comprises, "comprising X, Y and/or Z" means that any one or any two or three of X, Y, Z comprise.

The technical scheme of the utility model is described in detail below by specific examples. The following specific embodiments may be combined with or replaced with each other according to actual situations, and the same or similar concepts or processes may not be described in detail in some embodiments.

Embodiment one:

As shown in fig. 1 to 2, the present utility model provides a thermal cutting knife, comprising a machine body 1 and a cutter 2, wherein the front end of the machine body is provided with a clamping head, the cutter is detachably connected to the clamping head, the machine body 1 is provided with a load circuit 11, a detection circuit 12 and a control circuit 13, wherein:

The load circuit 11 comprises two conductive terminals arranged in the machine body, and the two conductive terminals are respectively and electrically connected with the cutter 2 in a contact way to form a loop and generate load current to heat the cutter 2;

The input end of the detection circuit 12 is electrically connected with the load circuit and generates a detection signal according to the load current, and the output end of the detection circuit 12 is electrically connected with the signal input end of the control circuit 13 and outputs the detection signal to the control circuit 13;

The signal output end of the control circuit 13 is electrically connected with the load circuit and adjusts the power output by the load circuit 11 to be matched with the size of the cutter 2 according to the detection signal so as to heat the cutter 2.

In this embodiment, the clamping head may adopt a common structure capable of being adjusted in tightness, the user connects the power cord to the mains supply or the product is charged with the power cord, opens the operation switch on the machine body, and the operation switch may be connected in series with the input end of the load circuit to provide the working power for the whole circuit. Because the equivalent resistance values of the cutters 2 with different sizes are different, the sizes of load currents generated after the cutters 2 with different sizes are connected into the load circuit 11 are also different, so that corresponding different detection signals are obtained based on the load currents with different sizes, the output power suitable for the current cutters 2 can be determined based on the detection signals, the output power is adjusted, and the cutters 2 are normally heated, so that the cutters 2 with different sizes are self-adaptively heated, the conditions that the cutters 2 are overheated or the heating speed is too slow are effectively prevented, the heating efficiency of the cutters 2 is ensured, and the service life of the cutters 2 is prolonged. Because the cutter is always connected in the load circuit, the cutter 2 can be preheated firstly, the same power can be output when the cutter 2 is preheated aiming at cutters with different sizes, the cutter 2 is preheated by lower power in the preheating process, the condition of overheating can not occur in a certain time, the detection signal can be obtained aiming at the load current in a period of time, the detection is not needed at the instant of electrifying, the detection fault tolerance rate can be improved, and the detection accuracy can be improved by detecting the load current at a plurality of time points. Since the cutter 2 is directly connected to the load circuit 11, the load circuit 11 is not limited by alternating current and direct current, so that the cutter can be applicable to alternating current and direct current products. And cutter 2 inserts in the load circuit 11 and is connected with organism 1 electricity in order to heat cutter 2, and the electric connection heating is direct with electric energy conversion heat energy, and the heating method is high-efficient, and energy loss is little, and the direct heating cutter can realize whole even heating, can not appear too high or low temperature, and electric connection heating can also be applicable to cutter 2 of various conductive material, including metal cutter 2 and non-metal cutter 2 etc. simultaneously cutter 2 detachable connection is on organism 1, when using cutter 2 of equidimension, only need dismantle change cutter 2, and the flexibility is high, interchangeability is good, and the maintenance of being convenient for.

As a possible embodiment, the load circuit 11 includes a first transformer T1 and a second transformer T2, the secondary of the first transformer T1 and the tool 2 form a loop, i.e. the conductive terminal is electrically connected to the secondary of the first transformer T1, where the load current is the current in the loop formed by the secondary of the first transformer T1 and the tool 2, the primary of the second transformer T2 is connected in series with the tool 2, the secondary of the second transformer T2 is connected to the detection circuit 12, and the detection circuit senses the load current through the second transformer, so as to generate the detection signal according to the load current. After the second transformer is connected with the cutter and the detection circuit, the cutter inserted into the machine body is different in size, the load current flowing through the primary side of the second transformer is also different, and the induction current of the secondary side of the second transformer is correspondingly changed, so that the detection circuit is connected with the secondary side of the second transformer, and can also generate a detection signal according to the load current and output the detection signal to the control circuit.

Specifically, the detection circuit 12 includes a detection element, the detection element may adopt a resistor R1, a current value and/or a voltage value of the resistor R1 changes with the load current, the detection signal is the current value and/or the voltage value of the resistor R1, when the machine body 1 is inserted into the tool 2 with different sizes, load currents with different sizes will be generated, so that the detection signals corresponding to the load currents with different sizes are different, that is, the current value and/or the voltage value of the resistor R1 in the detection circuit 12 are also different, so that the control circuit 13 can determine the output power suitable for the current tool based on the detection signals, the detection signal sampling is simple and convenient, and the power of the output matching tool is adjusted to heat the tool. Other common components for current or voltage sampling may be used in addition to resistor R1.

The detection circuit 12 further includes a rectifying element D3 and a filter circuit, the rectifying element D3 is electrically connected between the secondary of the second transformer T2 and the filter circuit, and the filter circuit is electrically connected to the resistor R1. By switching in the rectifying element D3, the alternating current can be converted into direct current, which is more advantageous for the processing of the control circuit 13 and for the stable output of the output power which is more matched with the size of the tool 2. In order to prevent unstable current in the detection circuit 12, a filter circuit is connected to the detection circuit 12, and the filter circuit can generate electromotive force, so that the change of current is resisted, the stability of the detection circuit 12 is ensured, the accurate detection of the current value and/or voltage value of the resistor R1 by the detection circuit 12 is facilitated, and a detection signal is accurately output to the control circuit 13. Specifically, the detection circuit 12 further includes a shunt resistor R2, one end of the shunt resistor R2 is connected between the resistor R1 and the input end of the control circuit 13, the other end of the shunt resistor R2 is grounded, the filter circuit includes a capacitor C2 and an inductor L1, the inductor L1 is connected in series with the resistor R1, one end of the capacitor C2 is connected between the inductor L1 and the resistor R1, and the other end of the capacitor C2 is grounded.

In one embodiment, referring specifically to fig. 2, the rectifying element D3 includes a diode, the anode of which is connected to the secondary of the second transformer T2, and the cathode of which is connected to the filter circuit. The detection circuit 12 can obtain a stable current value and/or voltage value of the resistor R1 through half-wave rectification of the diode, and can output a stable detection signal to the control circuit 13, so that the heat required by the cutter 2 is matched more, and the cutter 2 is heated more stably.

In another embodiment, as shown in fig. 3, the rectifying element D3 includes a rectifying bridge, a first end of the rectifying bridge is connected to a secondary end of the second transformer T2, a second end of the rectifying bridge is connected to the filtering circuit, a third end of the rectifying bridge is connected to a secondary end of the second transformer T2, and a fourth end of the rectifying bridge is grounded. Full-wave bridge rectification is performed through the rectifier bridge, alternating current is converted into stable direct current, and the control circuit 13 can acquire more stable detection signals and accurately judge the detection signals.

As a possible implementation manner, the load circuit 11 includes a forward push-pull circuit, the forward push-pull circuit is connected with a primary side of the first transformer T1, the primary side of the first transformer T1 includes a first winding and a second winding, the forward push-pull circuit includes a first switching tube Q1 and a second switching tube Q2, a gate of the first switching tube Q1 is connected with a first signal output end of the control circuit 13, a source of the first switching tube Q1 is connected with one end of the second winding, a drain of the first switching tube Q1 is connected with a positive electrode of a power supply and one end of the first winding, and an output of the second winding is determined according to on-off of the first switching tube Q1; the grid electrode of the second switching tube Q2 is connected with a second signal output end of the control circuit 13, the source electrode of the first switching tube Q1 is connected with the other end of the second winding and the negative electrode of the power supply, the drain electrode of the first switching tube Q1 is connected with the other end of the first winding, and the output of the first winding is determined according to the on-off state of the second switching tube Q2.

Specifically, the first switching tube Q1 and the second switching tube Q2 may be N-MOS tubes, and by correspondingly connecting two signal output ends of the control circuit 13 with the first switching tube Q1 and the second switching tube Q2 of the forward push-pull circuit, different signals are output at different signal output ends to control the first switching tube Q1 or the second switching tube Q2 to be turned on/off, so as to control the primary of the first transformer T1 to realize alternate output, which is favorable for satisfying the low-voltage heavy current with stable secondary output of the first transformer T1. Wherein the control signal may be high/low.

More specifically, the control circuit is also turned on unidirectionally to realize the alternate output of the first winding and the second winding of the first transformer T1 by connecting the diode D1 in parallel with the source and the drain of the first switching tube Q1 and connecting the diode D2 in parallel with the source and the drain of the second switching tube Q2.

As a possible implementation manner, the control circuit includes a control chip of a corresponding relation between preset current or voltage data and power required by the heating tool, and after receiving the detection signal, the control chip compares the detection signal with the preset current or voltage data to output the power required by the heating tool. Through the corresponding relation between the preset current or voltage data and the power required by the heating tool, the control chip can directly obtain the corresponding power according to the comparison of the detection signals, so that the power required by the corresponding heating tool is rapidly output, the calculated amount can be reduced, the control circuit can rapidly respond, the heating efficiency is improved, and the operation load of the control chip is reduced.

In another embodiment, the control circuit comprises a control chip with a preset function, and the control chip calculates the power required for outputting the heating tool according to the detection signal and the function. And calculating and outputting the power required by the heating cutter according to a control chip with a preset function, so that the power output by the load circuit is more accurate and is more matched with the size of the cutter. The function may be a current or voltage function common to the control chip itself.

Embodiment two:

As shown in fig. 4, the load circuit 11 includes a first transformer T1, a secondary of the first transformer T1 forms a loop with the tool 2, and the detection circuit 12 is connected to a primary of the first transformer T1, so as to generate a detection signal according to a load current. At this time, the load current is the current flowing through the primary of the first transformer T1. After the secondary of the first transformer is connected with the cutter, the sizes of the cutters inserted into the machine body are different, and the currents generated by the primary of the first transformer are different, so that the detection circuit is connected with the primary of the first transformer, the detection circuit can generate a detection signal according to the load current generated by the load circuit and output the detection signal to the control circuit, and the control circuit can adjust the load circuit to output power matched with the cutter in size according to the detection signal so as to heat the cutter. In the process, the characteristics of low-voltage large current and lifting voltage can be output by utilizing the secondary of the first transformer, so that the cutter 2 with smaller size can be suitable, and the size range of the cutter 2 suitable for products is widened.

Other matters not described in this embodiment can refer to embodiment one.

In the direct current product, the first transformer is not required, or the direct current transformer is adopted, and a rectifying element can be omitted in the detection circuit, so that the circuit structure is simplified.

In addition to the preferred embodiments described above, other embodiments of the present utility model are also contemplated as falling within the scope of the claimed utility model, as well as all other embodiments that may be made by one of ordinary skill in the art without making any inventive effort based on the embodiments of the present utility model.

Claims

1. The hot cutting knife comprises a machine body and a knife, wherein the front end of the machine body is provided with a clamping head, and the knife is detachably connected with the clamping head;

2. The thermal cutting blade of claim 1, wherein the load circuit comprises a first transformer, a secondary of the first transformer forming a loop with the blade.

3. The thermal cutting blade of claim 2, wherein the detection circuit is coupled to the primary of the first transformer to generate the detection signal based on the load current.

4. The hot cutting knife according to claim 2, wherein the load circuit comprises a forward push-pull circuit, the forward push-pull circuit is connected with a primary of a first transformer, the primary of the first transformer comprises a first winding and a second winding, the forward push-pull circuit comprises a first switching tube and a second switching tube, a grid electrode of the first switching tube is connected with a first signal output end of the control circuit, a source electrode of the first switching tube is connected with one end of the second winding, a drain electrode of the first switching tube is connected with a positive electrode of a power supply and one end of the first winding, and an output of the second winding is determined according to on-off of the first switching tube; the grid electrode of the second switching tube is connected with a second signal output end of the control circuit, the source electrode of the first switching tube is connected with the other end of the second winding and the negative electrode of the power supply, the drain electrode of the first switching tube is connected with the other end of the first winding, and the output of the first winding is determined according to the on-off state of the second switching tube.

5. The thermal cutting blade of claim 1 or 2, wherein the load circuit comprises a second transformer, the primary of the second transformer being connected in series with the blade, the secondary of the second transformer being connected to a detection circuit, the detection circuit inducing a load current through the second transformer, thereby generating the detection signal in dependence on the load current.

6. The thermal cutting burr of claim 5, wherein the detection circuit comprises a detection element, a current value and/or a voltage value of the detection element varies with the load current electrical signal, and the detection signal is the current value and/or the voltage value of the detection element.

7. The thermal cutting burr of claim 6, wherein the detection circuit further comprises a rectifying element and a filtering circuit, the rectifying element being electrically connected between the secondary of the second transformer and the filtering circuit, the filtering circuit being electrically connected to the detection element.

8. The thermal cutting blade of claim 7, wherein the rectifying element comprises a diode, the anode of the diode being connected to the secondary of the second transformer, the cathode of the diode being connected to the filter circuit.

9. The thermal cutting burr of claim 7, wherein the rectifying element comprises a rectifying bridge, a first end of the rectifying bridge is connected to a secondary end of the second transformer, a second end of the rectifying bridge is connected to the filter circuit, a third end of the rectifying bridge is connected to a secondary end of the second transformer, and a fourth end of the rectifying bridge is grounded.

10. The hot cutting knife according to claim 1, wherein the control circuit comprises a control chip for corresponding relation between preset current or voltage data and power required by the heating knife, the control chip is used for comparing and outputting the power required by the heating knife corresponding to the preset current or voltage data after receiving the detection signal, and/or the control circuit comprises a control chip preset with a function, and the control chip is used for calculating and outputting the power required by the heating knife according to the detection signal and the function.