Heat treatment apparatus

Abstract

The application relates to a heat treatment device. The heat treatment device comprises a plasma power supply and a vacuum chamber capable of containing a target workpiece, a positive electrode of the plasma power supply is connected with an outer wall of the vacuum chamber, and a negative electrode of the plasma power supply is connected with the target workpiece; the plasma power supply is used for outputting a direct-current pulse voltage to generate a composite discharge in the vacuum chamber to perform heat treatment on the target workpiece, and the composite discharge is alternating discharge of glow discharge and arc discharge. The heat treatment device provided by the application can not only avoid the problem that the prior art is not applicable to the heat treatment of non-ferromagnetic materials, but also effectively improve the heat treatment efficiency.

Description

Technical Field

[0001] This application relates to the field of heat treatment technology, and in particular to a heat treatment apparatus. Background Technology

[0002] Heat treatment of metallic materials is an important means of improving their performance. Compared with offline heat treatment, online heat treatment does not require secondary transfer of the workpiece and has the advantages of small footprint and high production efficiency.

[0003] In existing technologies, the workpiece is typically heat-treated using an online heat treatment method with medium-frequency heating.

[0004] However, this method is not only poorly applicable, but also has low heat treatment efficiency. Summary of the Invention

[0005] Therefore, it is necessary to provide a heat treatment apparatus that not only has good applicability but also high heat treatment efficiency to address the above-mentioned technical problems.

[0006] In a first aspect, this application provides a heat treatment apparatus, which includes:

[0007] A plasma power source and a vacuum chamber for accommodating the target workpiece, wherein the positive terminal of the plasma power source is connected to the outer wall of the vacuum chamber and the negative terminal of the plasma power source is connected to the target workpiece.

[0008] The plasma power source is used to output a DC pulse voltage to generate a composite discharge in the vacuum chamber for heat treatment of the target workpiece. The composite discharge is an alternating discharge of glow discharge and arc discharge.

[0009] In one embodiment, the plasma power supply includes a control circuit, a processing circuit, and an arc extinguishing circuit. The control circuit is connected to both the processing circuit and the arc extinguishing circuit. The processing circuit is used to convert the AC voltage input from the three-phase power supply into a DC pulse voltage and output the DC pulse voltage. The control circuit is used to acquire the DC pulse voltage output by the processing circuit in real time, and when the processing circuit is determined to be in a first arc ignition state based on the DC pulse voltage, it sends a start signal to the arc extinguishing circuit. The arc extinguishing circuit is used to turn on the insulated gate bipolar transistor to extinguish the arc discharge upon receiving the start signal.

[0010] In one embodiment, the control circuit is further configured to send a shutdown signal to the arc extinguishing circuit after waiting for a preset time; the arc extinguishing circuit is configured to turn off the insulated gate bipolar transistor upon receiving the shutdown signal.

[0011] In one embodiment, the processing circuit includes a rectifier-filter circuit, an inverter circuit, a high-frequency transformer circuit, and a fast recovery rectifier circuit. The inverter circuit is connected to both the rectifier-filter circuit and the high-frequency transformer circuit. The rectifier-filter circuit converts the AC voltage from the three-phase power supply into a constant DC voltage and sends the constant DC voltage to the inverter circuit. The inverter circuit converts the constant DC voltage into a high-frequency AC pulse voltage and sends the high-frequency AC pulse voltage to the high-frequency transformer circuit. The high-frequency transformer circuit converts the high-frequency AC pulse voltage into a high-frequency, high-voltage AC pulse voltage and sends the high-frequency, high-voltage AC pulse voltage to the fast recovery rectifier circuit. The fast recovery rectifier circuit rectifies the high-frequency, high-voltage AC pulse voltage to obtain a DC pulse voltage and outputs the DC pulse voltage.

[0012] In one embodiment, the control circuit is connected to the inverter circuit; the control circuit is further configured to send a pulse width modulation signal to the inverter circuit according to the DC pulse voltage, and to stop sending the pulse width modulation signal to the inverter circuit when the processing circuit is determined to be in a first arcing state according to the DC pulse voltage.

[0013] In one embodiment, the control circuit is further configured to continue executing the step of sending the pulse width modulation signal to the inverter circuit according to the DC pulse voltage after the preset waiting time.

[0014] In one embodiment, the heat treatment apparatus further includes a first micro-positive pressure chamber and a second micro-positive pressure chamber. The first micro-positive pressure chamber includes a first sub-through hole and a second sub-through hole, and the second micro-positive pressure chamber includes a third sub-through hole and a fourth sub-through hole. The vacuum chamber further includes a first through hole and a second through hole disposed at both ends. The first micro-positive pressure chamber is disposed at the first through hole end of the vacuum chamber, and the second micro-positive pressure chamber is disposed at the second through hole end of the vacuum chamber. The first sub-through hole, the first through hole, the second through hole, and the third sub-through hole are used to place the target workpiece. The first micro-positive pressure chamber and the second micro-positive pressure chamber are used to maintain a micro-positive pressure environment when a protective gas is introduced. The protective gas is introduced into the first micro-positive pressure chamber and the second micro-positive pressure chamber through the second sub-through hole and the fourth sub-through hole, respectively.

[0015] In one embodiment, the vacuum chamber further includes a third through-hole for discharging gas from the vacuum chamber under the action of a vacuum pump.

[0016] In one embodiment, the heat treatment apparatus further includes a protective cover; wherein the vacuum chamber is disposed within the protective cover, and a cooling medium is disposed between the outer wall of the vacuum chamber and the protective cover.

[0017] In one embodiment, the heat treatment apparatus further includes a clamping wheel for fixing the target workpiece; wherein the negative terminal of the plasma power source is connected to the target workpiece via the clamping wheel.

[0018] The aforementioned heat treatment apparatus includes a plasma power source and a vacuum chamber for accommodating the target workpiece. The positive terminal of the plasma power source is connected to the outer wall of the vacuum chamber, and the negative terminal is connected to the target workpiece. The plasma power source outputs a DC pulse voltage to generate a composite discharge within the vacuum chamber for heat treatment of the target workpiece. This composite discharge is an alternating discharge of glow discharge and arc discharge. The heat treatment apparatus provided in this application, based on the stable glow discharge and arc discharge generated by the plasma power source within the vacuum chamber, achieves heat treatment of the target workpiece. This not only avoids the problem that existing technologies are not suitable for heat treatment of non-ferromagnetic materials but also effectively improves the efficiency of heat treatment. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the heat treatment apparatus in one embodiment;

[0021] Figure 2 This is a waveform diagram of the voltage and current of the plasma power supply under ideal conditions in one embodiment;

[0022] Figure 3 This is a structural block diagram of a plasma power source in one embodiment;

[0023] Figure 4 This is a structural diagram of the processing circuit in one embodiment;

[0024] Figure 5 This is a circuit diagram of the processing circuit in one embodiment;

[0025] Figure 6 This is a signal waveform diagram of various points in the processing circuit of one embodiment;

[0026] Figure 7 This is a schematic diagram of the control circuit in one embodiment;

[0027] Figure 8 This is a block diagram of the control circuit and inverter circuit in one embodiment;

[0028] Figure 9 The waveforms of voltage and current during plasma power supply discharge are shown in one embodiment. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0030] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0031] In this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, for example, two, three, etc., unless otherwise explicitly specified.

[0032] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0033] Heat treatment of metallic materials is an important means of improving their performance. Compared with offline heat treatment, online heat treatment does not require secondary transfer of the workpiece and has the advantages of small footprint and high production efficiency.

[0034] In existing technologies, the workpiece is typically heat-treated using an online heat treatment method with medium-frequency heating.

[0035] However, for ferromagnetic materials, medium-frequency heating has a high energy coupling coefficient and heating efficiency. But for non-ferromagnetic materials such as copper, aluminum or austenitic stainless steel, the electromagnetic coupling coefficient of medium-frequency heating is significantly lower, which in turn leads to lower heating efficiency. In particular, when using medium-frequency heating to heat treat copper workpieces with good conductivity, the energy consumed by the medium-frequency coil is even higher than the energy of the workpiece being heated, resulting in extremely low heat treatment efficiency for copper materials.

[0036] In view of this, this application provides a heat treatment apparatus with high applicability and high heat treatment efficiency.

[0037] In one exemplary embodiment, such as Figure 1 As shown, the heat treatment apparatus 100 includes a plasma power supply 101 and a vacuum chamber 102 for accommodating the target workpiece. The positive electrode of the plasma power supply 101 is connected to the outer wall of the vacuum chamber 102, and the negative electrode of the plasma power supply 101 is connected to the target workpiece 103.

[0038] The plasma power supply 101 is used to output a DC pulse voltage to generate a composite discharge in the vacuum chamber 102 for heat treatment of the target workpiece 103. The composite discharge is an alternating discharge of glow discharge and arc discharge.

[0039] Optionally, the plasma power source 101 refers to a device for generating plasma, which can excite stable plasma by providing a high-frequency, high-amplitude pulse voltage.

[0040] Optionally, the composite discharge refers to the alternating discharge of the glow discharge and the arc discharge according to a preset strategy.

[0041] Optionally, the discharge area of ​​the composite discharge is the gap between the inner wall of the vacuum chamber 102 and the target workpiece 103.

[0042] In one possible implementation, although the voltage generated by glow discharge is high, the low current density results in low power per unit area, which cannot meet the requirements of high-power online heat treatment. Increasing the voltage or current would cause the glow discharge to transition into arc discharge, leading to crater damage on the surface of the target workpiece. Therefore, this composite discharge refers to generating only one arc discharge during each voltage pulse. This not only effectively ensures the power required for online heat treatment but also avoids continuous arc discharge damage to the target workpiece. Specifically, the waveforms of the voltage and current of this plasma power supply discharge can be seen as follows: Figure 2 As shown.

[0043] Optionally, the vacuum chamber 102 can be a low vacuum chamber, which can be used to provide a low vacuum environment.

[0044] In one possible implementation, the low vacuum chamber is cylindrical and can be cut into two equal parts along the axial direction, namely a first vacuum chamber and a second vacuum chamber. The first vacuum chamber and the second vacuum chamber are movably connected on one side, and the target workpiece can be placed into the low vacuum chamber through the other side of the first vacuum chamber and the second vacuum chamber.

[0045] In another possible implementation, the low vacuum chamber can be cylindrical and have a through hole in the axial direction through which the target workpiece can be inserted into the low vacuum chamber.

[0046] Optionally, the target workpiece 103 can be a tubular or rod-shaped workpiece made of metal.

[0047] In one possible implementation, after the target workpiece 103 is placed into the vacuum chamber, the positive terminal of the plasma power supply 101 can be connected to the outer wall of the vacuum chamber 102, and the negative terminal of the plasma power supply 101 can be connected to the target workpiece 103. After connection, the plasma power supply 101 is turned on to enter the working state, so as to output DC pulse voltage and generate a composite discharge in the vacuum chamber 102 to achieve heat treatment of the target workpiece 103.

[0048] The aforementioned heat treatment apparatus includes a plasma power source and a vacuum chamber for accommodating the target workpiece. The positive terminal of the plasma power source is connected to the outer wall of the vacuum chamber, and the negative terminal is connected to the target workpiece. The plasma power source outputs a DC pulse voltage to generate a composite discharge within the vacuum chamber for heat treatment of the target workpiece. This composite discharge is an alternating discharge of glow discharge and arc discharge. The heat treatment apparatus provided in this application, based on the stable glow discharge and arc discharge generated by the plasma power source within the vacuum chamber, achieves heat treatment of the target workpiece. This not only avoids the problem that existing technologies are not suitable for heat treatment of non-ferromagnetic materials but also effectively improves the efficiency of heat treatment.

[0049] In one exemplary embodiment, such as Figure 3 As shown, the plasma power source includes a control circuit 201, a processing circuit 202, and an arc extinguishing circuit 203. The control circuit 201 is connected to the processing circuit 202 and the arc extinguishing circuit 203, respectively.

[0050] The processing circuit 202 is used to convert the AC voltage of the three-phase power input into a DC pulse voltage and output the DC pulse voltage; the control circuit 201 is used to acquire the DC pulse voltage output by the processing circuit in real time, and send a start signal to the arc extinguishing circuit when the processing circuit is determined to be in the first arc ignition state based on the DC pulse voltage; the arc extinguishing circuit 203 is used to turn on the insulated gate bipolar transistor to extinguish the arc discharge when the start signal is received.

[0051] In an optional embodiment of this application, such as Figure 4 As shown, the processing circuit includes a rectifier filter circuit 301, an inverter circuit 302, a high-frequency transformer circuit 303, and a fast recovery rectifier circuit 304. The inverter circuit 302 is connected to the rectifier filter circuit 301 and the high-frequency transformer circuit 303, and the high-frequency transformer circuit 303 is connected to the fast recovery rectifier circuit 304.

[0052] The rectifier-filter circuit 301 converts the AC voltage from the three-phase power supply into a constant DC voltage and sends the constant DC voltage to the inverter circuit 302. The inverter circuit 302 converts the constant DC voltage into a high-frequency AC pulse voltage and sends the high-frequency AC pulse voltage to the high-frequency transformer circuit 303. The high-frequency transformer circuit 303 converts the high-frequency AC pulse voltage into a high-frequency high-voltage AC pulse voltage and sends the high-frequency high-voltage AC pulse voltage to the fast recovery rectifier circuit 304. The fast recovery rectifier circuit 304 rectifies the high-frequency high-voltage AC pulse voltage to obtain a DC pulse voltage and outputs the DC pulse voltage.

[0053] In one possible implementation method Figure 4 In this context, "three-phase" refers to a three-phase power supply, "rectifier and filter" refers to rectifier and filter circuit 301, "inverter" refers to inverter circuit 302, "high-frequency transformer circuit" refers to high-frequency transformer circuit 303, and "fast recovery rectification" refers to fast recovery rectification circuit 304. The circuit diagram of this processing circuit can be seen as follows: Figure 5 As shown, Figure 5 The inverter circuit 302 adopts a full-bridge inverter circuit, including a first bridge arm and a second bridge arm. The first bridge arm includes a first upper bridge arm switch and a first lower bridge arm switch, and the second bridge arm includes a second upper bridge arm switch and a second lower bridge arm switch. The midpoint of the first bridge arm and the midpoint of the second bridge arm are the output terminals of the full-bridge inverter circuit, and the output terminals output a high-frequency AC pulse voltage. Figure 5 The high-frequency transformer in the circuit is also known as the high-frequency transformer circuit. Its input terminal is connected to the output terminal of the inverter circuit 302. It isolates and regulates the high-frequency AC pulse voltage output from the inverter circuit 302, outputting a high-frequency, high-voltage AC pulse voltage. This high-frequency, high-voltage AC pulse voltage is then input to the fast recovery rectifier circuit 304. The first output terminal of the fast recovery rectifier circuit 304 is the output terminal of the plasma power supply. It rectifies the high-frequency, high-voltage AC pulse voltage to output a DC pulse voltage Uo. The fast recovery rectifier circuit 304 consists of a full-bridge rectifier circuit composed of four fast recovery diodes. The reverse recovery time of the fast recovery diodes should be less than 120ns. Figure 5 In the diagram, Uf refers to the output voltage of the plasma power supply, and If refers to the output current of the plasma power supply. The signal waveforms at various points in the processing circuit can be seen as follows: Figure 6 As shown.

[0054] Optionally, the control circuit refers to a circuit equipped with a controller.

[0055] In an optional embodiment of this application, the control circuit includes a constant voltage control circuit 401.

[0056] In one possible implementation, such as Figure 7 As shown, taking the controller in this control circuit as an example (SG3525), the input terminal of the constant voltage control circuit 401 is connected to the sampling output terminal of the fast recovery rectifier circuit to obtain the voltage feedback signal corresponding to the DC pulse voltage output by the fast recovery rectifier circuit, and the voltage feedback signal Uf and the preset voltage signal ( Figure 7 After comparing the voltage setting in the input voltage sensor with the voltage setting in the input voltage sensor, the output voltage is adjusted by the PID controller and sent to the compensation input pin of the SG3525 controller. This is used to control the amplitude of the DC pulse voltage according to the target set value, so as to achieve the purpose of constant voltage control. The target set value can be set by the technician according to the actual needs.

[0057] In an optional embodiment of this application, the control circuit further includes an arc extinguishing control circuit 402.

[0058] In one possible implementation, such as Figure 7 As shown, taking the SG3525 controller in this control circuit as an example, the input terminal of the arc extinguishing control circuit 402 is connected to the sampling output terminal of the fast recovery rectifier circuit. The DC pulse voltage and current output by the fast recovery rectifier circuit are used to determine whether it is the first arc state. If it is determined to be the first arc state, a timer records the duration of the first arc state. When the duration of the first arc state exceeds a preset time, the monostable circuit is triggered to output a high level. This preset time can be set by technicians according to actual needs; for example, the preset time can be one PWM cycle. The high level output by the arc extinguishing control circuit is equivalent to the aforementioned start signal, used to start the arc extinguishing circuit. Figure 7 (The arc-extinguishing device in the middle) to extinguish the electric arc.

[0059] As mentioned above, the first arc state can be determined by the DC pulse voltage and current output by the fast recovery rectifier circuit.

[0060] In one possible implementation, the output voltage and output current of the plasma power supply can be determined first based on the DC pulse voltage and current output by the fast recovery rectifier circuit. When the output voltage of the plasma power supply is lower than 1 / 3 of the normal glow discharge voltage and the output current is greater than twice the normal value of the glow discharge current, it can be determined as the first arc initiation state. When the first arc initiation state is determined, the time of the first arc initiation state is recorded by a timer. When the time of the first arc initiation state is greater than a preset time, the monostable circuit is triggered to output a high level.

[0061] In an optional embodiment of this application, such as Figure 5 As shown, the arc extinguishing circuit 203 is connected in parallel to the output terminal of the processing circuit, which is also the output terminal of the fast recovery rectifier circuit 304. The arc extinguishing circuit 203 includes a high-speed IGBT with strong resistance to current surges. When the processing circuit is determined to be in the first arc initiation state, the IGBT is controlled to conduct in order to unload the arc energy and extinguish the arc. The IGBT is the insulated gate bipolar transistor mentioned above.

[0062] In an optional embodiment of this application, such as Figure 8 As shown, the control circuit 201 is connected to the inverter circuit 302.

[0063] The control circuit 201 is also used to send a pulse width modulation signal to the inverter circuit 302 according to the DC pulse voltage, and to stop sending the pulse width modulation signal to the inverter circuit 302 when the processing circuit is determined to be in the first arcing state according to the DC pulse voltage.

[0064] In an optional embodiment of this application, the control circuit further includes an inverter control circuit 403.

[0065] In one possible implementation, such as Figure 7 As shown, the inverter control circuit 403 consists of an SG3525 controller, a trigger, and logic circuits. It is used to control the duty cycle of the AC pulse voltage signal of the inverter circuit 403. The duty cycle is controlled by the voltage at pin 9. The output terminal of the inverter control circuit 403 is connected to the second input terminal of the inverter circuit. It is used to control the opening and closing of each switching device of the inverter circuit, thereby realizing the control of the power supply output voltage.

[0066] In an optional embodiment of this application, the control circuit is further configured to send a shutdown signal to the arc extinguishing circuit after waiting for a preset time; the arc extinguishing circuit is configured to turn off the insulated gate bipolar transistor upon receiving the shutdown signal.

[0067] In one possible implementation, the preset time can be between 200-300µs, and can also be set by technicians according to actual needs. After waiting for the preset time, a shutdown signal is sent to the arc extinguishing circuit to turn off the insulated gate bipolar transistor in the arc extinguishing circuit.

[0068] In an optional embodiment of this application, the control circuit is further configured to continue executing the step of sending the pulse width modulation signal to the inverter circuit according to the DC pulse voltage after waiting for the preset time.

[0069] In one possible implementation, the preset time can be between 200-300µs, and can also be set by technicians according to actual needs. After waiting for the preset time, the step of sending the pulse width modulation signal to the inverter circuit according to the DC pulse voltage continues to be executed in order to continue generating glow discharge.

[0070] In an optional embodiment of this application, the plasma power supply is further provided with an overcurrent protection circuit and an overheat protection circuit. The input terminal of the overcurrent protection circuit is connected to a sampling resistor on the main circuit after the rectifier and filter circuit to monitor the current on the main circuit. The input terminal of the overheat protection circuit is connected to a thermistor to monitor the temperature of the power supply during operation. The output is connected to the inverter control circuit, which will shut down the inverter circuit if overcurrent or overheating occurs.

[0071] In one exemplary embodiment, such as Figure 1 As shown, the heat treatment apparatus 100 further includes a first micro-positive pressure chamber 104 and a second micro-positive pressure chamber 105. The first micro-positive pressure chamber 104 includes a first sub-through hole 1041 and a second sub-through hole 1042. The second micro-positive pressure chamber 105 includes a third sub-through hole 1051 and a fourth sub-through hole 1052. The vacuum chamber 102 also includes a first through hole 1021 and a second through hole 1022 disposed at both ends. The first micro-positive pressure chamber 104 is disposed at the first through hole 1021 end of the vacuum chamber 102, and the second micro-positive pressure chamber 104 is disposed at the second through hole 1022 end of the vacuum chamber 102.

[0072] The first sub-through hole 1041, the first through hole 1021, the second through hole 1022, and the third sub-through hole 1051 are used to place the target workpiece 103; the first micro-positive pressure chamber 104 and the second micro-positive pressure chamber 105 are used to maintain a micro-positive pressure environment when a protective gas is introduced, and the protective gas is introduced into the first micro-positive pressure chamber 104 and the second micro-positive pressure chamber 105 through the second sub-through hole 1042 and the fourth sub-through hole 1052, respectively.

[0073] In one possible implementation, the protective gas can be introduced into the first micro-positive pressure chamber 104 and the second micro-positive pressure chamber 105 through the second sub-through hole 1042 and the fourth sub-through hole 1052, respectively, to maintain a micro-positive pressure environment and prevent oxidation of the target workpiece.

[0074] In one exemplary embodiment, such as Figure 1 As shown, the vacuum chamber 102 also includes a third through hole 1023.

[0075] The third through hole 1023 is used to discharge the gas in the vacuum chamber 102 under the action of the vacuum pump.

[0076] In one possible implementation, the third through hole 1023 can be used by a vacuum pump to expel the gas in the vacuum chamber 102 to prevent the target workpiece 103 from oxidizing during online heat treatment.

[0077] In one exemplary embodiment, such as Figure 1 As shown, the heat treatment apparatus 100 also includes a protective cover 106.

[0078] The vacuum chamber 102 is disposed inside the protective cover 106, and a cooling medium is disposed between the outer wall of the vacuum chamber 102 and the protective cover 106.

[0079] In an optional embodiment of this application, the anode is disposed inside the protective cover, the target workpiece is the cathode, and the space between the anode and the protective cover is filled with cooling oil, which achieves both cooling of the anode and electrical isolation protection.

[0080] In one exemplary embodiment, such as Figure 1 As shown, the heat treatment apparatus 100 also includes a clamping wheel 107 for fixing the target workpiece 103.

[0081] The negative terminal of the plasma power source 101 is connected to the target workpiece via the pressure roller 107.

[0082] In one possible implementation, the negative terminal of the plasma power source 101 is connected to the target workpiece 103 via the clamping wheel 107 and connected to the protective ground wire for electrical safety.

[0083] It should be noted that the inventors of this application have actually measured the voltage and current output by the plasma power supply in the heat treatment apparatus of this application, and the specific measurement results are as follows: Figure 9 As shown, it can be verified that the plasma power source in this application can achieve a combined discharge in the vacuum chamber, generating only one arc discharge during each voltage pulse, thus ensuring the power required for online heat treatment and avoiding damage to the target workpiece from continuous arc discharge. Figure 9 The upper part of the signal is a voltage signal, and the lower part is a current signal. Both the output voltage and current are DC pulse signals. An electric arc discharge occurs in the latter half of the second pulse.

[0084] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0085] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A heat treatment apparatus, characterized in that, The heat treatment apparatus includes a plasma power source and a vacuum chamber for accommodating the target workpiece. The positive terminal of the plasma power source is connected to the outer wall of the vacuum chamber, and the negative terminal of the plasma power source is connected to the target workpiece. The plasma power supply is used to output a DC pulse voltage to generate a composite discharge in the vacuum chamber for heat treatment of the target workpiece. The composite discharge is an alternating discharge of glow discharge and arc discharge. The composite discharge generates an arc discharge only once during each voltage pulse. The plasma power supply includes a control circuit, a processing circuit, and an arc extinguishing circuit. The control circuit is connected to both the processing circuit and the arc extinguishing circuit. The processing circuit is used to convert the AC voltage of the three-phase power input into a DC pulse voltage and output the DC pulse voltage. The control circuit is used to acquire the DC pulse voltage output by the processing circuit in real time, and send a start signal to the arc extinguishing circuit when the processing circuit is determined to be in the first arc ignition state based on the DC pulse voltage. The arc extinguishing circuit is used to turn on the insulated gate bipolar transistor to extinguish the arc discharge when the start signal is received. The control circuit is also used to send a shutdown signal to the arc extinguishing circuit after waiting for a preset time; The arc-extinguishing circuit is also used to turn off the insulated gate bipolar transistor upon receiving the shutdown signal.

2. The heat treatment apparatus according to claim 1, characterized in that, The processing circuit includes a rectifier filter circuit, an inverter circuit, a high-frequency transformer circuit, and a fast recovery rectifier circuit. The inverter circuit is connected to the rectifier filter circuit and the high-frequency transformer circuit, respectively. The high-frequency transformer circuit and the fast recovery rectifier circuit are connected. The rectifier and filter circuit is used to convert the AC voltage sent by the three-phase power supply into a DC constant voltage and send the DC constant voltage to the inverter circuit. The inverter circuit is used to convert the DC constant voltage into a high-frequency AC pulse voltage and send the high-frequency AC pulse voltage to the high-frequency transformer circuit. The high-frequency transformer circuit is used to convert the high-frequency AC pulse voltage into a high-frequency high-voltage AC pulse voltage, and send the high-frequency high-voltage AC pulse voltage to the fast recovery rectifier circuit. The fast recovery rectifier circuit is used to rectify the high-frequency high-voltage AC pulse voltage to obtain a DC pulse voltage and output the DC pulse voltage.

3. The heat treatment apparatus according to claim 2, characterized in that, The control circuit is connected to the inverter circuit; The control circuit is further configured to send a pulse width modulation signal to the inverter circuit based on the DC pulse voltage, and to stop sending the pulse width modulation signal to the inverter circuit when the processing circuit is determined to be in a first arcing state based on the DC pulse voltage.

4. The heat treatment apparatus according to claim 3, characterized in that, The control circuit is further configured to continue executing the step of sending the pulse width modulation signal to the inverter circuit according to the DC pulse voltage after the preset waiting time.

5. The heat treatment apparatus according to claim 1, characterized in that, The heat treatment apparatus further includes a first micro-positive pressure chamber and a second micro-positive pressure chamber. The first micro-positive pressure chamber includes a first sub-through hole and a second sub-through hole. The second micro-positive pressure chamber includes a third sub-through hole and a fourth sub-through hole. The vacuum chamber further includes a first through hole and a second through hole disposed at both ends. The first micro-positive pressure chamber is disposed at the first through hole end of the vacuum chamber, and the second micro-positive pressure chamber is disposed at the second through hole end of the vacuum chamber. The first sub-through hole, the second through hole, and the third sub-through hole are used to place the target workpiece; The first micro-positive pressure chamber and the second micro-positive pressure chamber are used to maintain a micro-positive pressure environment when a protective gas is introduced. The protective gas is introduced into the first micro-positive pressure chamber and the second micro-positive pressure chamber through the second sub-through hole and the fourth sub-through hole, respectively.

6. The heat treatment apparatus according to claim 5, characterized in that, The vacuum chamber also includes a third through-hole; The third through hole is used to discharge the gas in the vacuum chamber under the action of the vacuum pump.

7. The heat treatment apparatus according to claim 1, characterized in that, The heat treatment apparatus also includes a protective cover; The vacuum chamber is located inside the protective cover, and a cooling medium is provided between the outer wall of the vacuum chamber and the protective cover.

8. The heat treatment apparatus according to claim 1, characterized in that, The heat treatment apparatus also includes a clamping wheel for fixing the target workpiece; The negative terminal of the plasma power source is connected to the target workpiece via the pressure roller.

9. The heat treatment apparatus according to claim 1, characterized in that, The discharge area of ​​the composite discharge is the gap between the inner wall of the vacuum chamber and the target workpiece.

10. The heat treatment apparatus according to claim 1, characterized in that, The vacuum chamber is cylindrical and is divided into two equal parts along the axial direction, namely the first vacuum chamber and the second vacuum chamber.

Images