Spark protection circuit of high-frequency welding machine

Abstract

The utility model provides a spark protection circuit of a high frequency welding machine, which comprises a drive circuit and a spark detection circuit, the spark detection circuit comprises an optocoupler switch U1, a bidirectional thyristor V1 and a relay switch K1, a first pin of the optocoupler switch U1 is connected with one end of the bidirectional thyristor V1, a second pin of the optocoupler switch U1 is grounded, and a third pin of the optocoupler switch U1 is grounded. On one hand, a third pin of the optocoupler switch U1 is connected with the other end of the driving circuit, on the other hand, the third pin of the optocoupler switch U1 is connected with an external direct-current power supply, and a fourth pin of the optocoupler switch U1 is grounded; the other end of the bidirectional thyristor V1 is connected with a power supply, the control end of the bidirectional thyristor V1 is connected with one end of a relay switch K1, and the other end of the relay switch K1 is connected with a direct-current power supply; the short circuit protection circuit is simple in structure, can timely control the welding device to stop when the welding machine is short-circuited, and prevents sparks generated by short circuit from damaging workpieces.

Description

Technical Field

[0001] The utility model relates to the technical field of spark detection of a fusion splicer, in particular to a spark protection circuit for a high-frequency fusion splicer. Background Art

[0002] High frequency wave means high-frequency wave. High frequency wave and ultrasonic wave are two different concepts. High frequency wave refers to an electromagnetic wave with a frequency greater than 100KHz, and ultrasonic wave refers to a sound wave with a frequency exceeding 20 kHz. The welding principle and fusion principle of high frequency wave are also different from those of ultrasonic wave. High frequency wave uses high-frequency electromagnetic field to make the molecules inside the material collide violently with each other to generate high temperature to achieve the purpose of welding and fusion, while ultrasonic wave uses the principle of heat generation by friction to generate a large amount of heat to achieve the purpose of welding and fusion. High frequency wave has a wide range of application fields. At present, there are high-frequency plastic fusion splicers, high-frequency leather and plastic fusing machines, high-frequency folding box indentation machines, high-frequency metal heating machines, etc. A high-frequency fusion splicer uses a high-frequency electric field to make the molecules inside the plastic oscillate to generate heat energy for fusing various products. Under the action of the high-frequency electric field, the dielectric material activates the positive charged molecules, making the positive charged molecules of the dielectric material move at high speed and generate heat by friction to fuse the plastic. However, when processing a conveyor belt with a high-frequency welding machine, sometimes the upper and lower templates are directly connected, causing the template to be grounded and resulting in a short circuit in the circuit, generating sparks. If there is no spark protection, the welding die and the conveyor belt will be burned out.

[0003] In the patent document with the Chinese patent application number 200810072456.3 and the publication date of June 30, 2010, a spark protector for an HSI high-frequency machine is disclosed. It uses an IC chip, crystal elements, and generates oscillation pulses with a weak voltage to trigger the thyristor to conduct, forming a closed loop with the grid resistor of the electron tube of the high-frequency machine. A negative bias current is applied to the grid of the electron tube, and the high-frequency machine stops oscillating instantly (1 - 2 microseconds), thereby protecting the workpiece, the die, the eyesight, and the environment, preventing the raw materials from being severely damaged, and at the same time ensuring that the core component of the high-frequency machine - the electron tube is not impacted by a large current and prolonging its service life.

[0004] For the prior art similar to this document, in order to make the protector respond sensitively and the protection action fast, usually the wiring of the spark protection circuit becomes complex, which easily leads to the problems of high maintenance cost and great maintenance difficulty of the circuit after long-term use. Summary of the Invention

[0005] The utility model provides a spark protection circuit for a high-frequency fusion splicer. The circuit structure is simple. When the fusion splicer is short-circuited, it can timely control the fusion device to stop, preventing the sparks generated by the short circuit from damaging the workpiece.

[0006] To achieve the above object, the technical solution of the utility model is: a spark protection circuit for a high-frequency welding machine, including a driving circuit and a spark detection circuit. The spark detection circuit includes an optocoupler switch U1, a bidirectional thyristor V1, and a relay switch K1. The first pin of the optocoupler switch U1 is connected to one end of the bidirectional thyristor V1. The second pin of the optocoupler switch U1 is grounded. The third pin of the optocoupler switch U1 is connected to the other end of the driving circuit on the one hand and is connected to an external DC power supply on the other hand. The fourth pin of the optocoupler switch U1 is grounded. The other end of the bidirectional thyristor V1 is connected to the power supply. The control end of the bidirectional thyristor V1 is connected to one end of the relay switch K1, and the other end of the relay switch K1 is connected to the DC power supply.

[0007] In the above structure, a driving circuit is provided to connect to an external high-frequency driving power supply to drive the welding device to work. If the welding device contacts the ground and a short circuit occurs, the relay switch K1 closes, so that the control end of the bidirectional thyristor V1 gets electricity, making the bidirectional thyristor V1 conduct, and then the optocoupler switch U1 opens. The external DC power supply is grounded through the optocoupler switch, making the high frequency ineffective and the switching circuit disconnect, so that the welding device stops working to protect the workpiece. During normal operation, the optocoupler switch U1 is disconnected, so that the external DC power supply supplies power to one end of the driving circuit, making the external high-frequency power supply form a loop through the switching circuit and making the welding device in a working state. The circuit structure is simple. When a short circuit occurs in the welding machine and sparks are generated, the welding device can be timely controlled to stop, preventing the generated sparks from damaging the workpiece.

[0008] Further, the driving circuit includes a MOS tube VT1 and an electron tube grid resistor R0. The source S of the MOS tube VT1 is grounded. The drain D of the MOS tube VT1 is connected to one end of the electron tube grid resistor R0. The gate G of the MOS tube VT1 is connected to the third pin of the optocoupler switch and the external DC power supply. The other end of the electron tube grid resistor R0 is connected to the other end of the welding device, and one end of the welding device is connected to the switching circuit.

[0009] With the above settings, by setting the MOS tube VT1, during normal operation, the external DC power supply supplies power to the gate G of the MOS tube VT1 and makes the MOS tube VT1 conduct. Thus, the external high-frequency power supply can pass through the switching circuit, pass through the MOS tube VT1, and be grounded to form a loop. Therefore, the external high-frequency power supply supplies power to the switching circuit to make the welding device work.

[0010] Further, the switching circuit includes a switch P1 and a contactor M1. One end of the switch P1 is connected to the external high-frequency power supply. The other end of the switch P1 is connected to one end of the welding device. The other end of the welding device is connected to the driving circuit. When the contactor M1 is energized, it drives the switch P1 to be normally closed.

[0011] With the above settings, when the circuit is short-circuited, the driving circuit loses power, causing the contactor M1 to disconnect, thereby opening the switch P1, further disconnecting the power supply from the welding device, and thus driving the welding device to stop working.

[0012] Further, the gate G of the MOS transistor VT1 is also grounded through a resistor R2.

[0013] With the above settings, the resistor R2 provides a voltage to the gate of the MOS transistor.

[0014] Further, a resistor R3 is provided between the third pin of the opto-coupler switch U1 and the external DC power supply.

[0015] With the above settings, the resistor R3 prevents the current in the opto-coupler switch U1 circuit from being too large, thereby causing damage to the circuit.

[0016] Further, the resistance value of the electron tube grid resistor R0 is 3500 ohms.

[0017] With the above settings, it is possible to prevent damage to the MOS transistor VT1 by passing through a high-value resistor with an external high-frequency input power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a circuit schematic diagram of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] The present utility model will be further described in detail below with reference to the drawings and specific embodiments.

[0020] As Figure 1 shown, a spark protection circuit for a high-frequency welding machine includes a driving circuit 1 and a spark detection circuit 2. The spark detection circuit 2 includes an opto-coupler switch U1, a bidirectional thyristor V1, and a relay switch K1. The first pin of the opto-coupler switch U1 is connected to one end of the bidirectional thyristor V1, the second pin of the opto-coupler switch U1 is grounded, the third pin of the opto-coupler switch U1 is connected to the driving circuit 1 on the one hand, and the third pin of the opto-coupler switch U1 is connected to the external DC power supply on the other hand. The fourth pin of the opto-coupler switch U1 is grounded; the other end of the bidirectional thyristor V1 is connected to the power supply, the control end of the bidirectional thyristor V1 is connected to one end of the relay switch K1, the other end of the relay switch K1 is connected to the DC power supply, one end of the driving circuit 1 is connected to the high-frequency input end through a switching circuit, and the closing of the relay switch K1 makes the bidirectional thyristor V1 conduct.

[0021] The driving circuit includes an MOS transistor VT1 and a grid resistor R0 of the electron tube. The source S of the MOS transistor VT1 is grounded. The drain D of the MOS transistor VT1 is connected to one end of the grid resistor R0 of the electron tube. The gate G of the MOS transistor VT1 is connected to the 3rd pin of the opto-coupler switch and an external DC power supply. The other end of the grid resistor R0 of the electron tube is connected to the other end of the welding device. The resistance value of the grid resistor R0 of the electron tube is 3500 ohms. This enables the external high-frequency input power supply to pass through a high-value resistor to prevent damage to the MOS transistor VT1. One end of the welding device is connected to the switching circuit. By setting the MOS transistor VT1, during normal operation, the external DC power supply supplies power to the gate G of the MOS transistor VT1 and makes the MOS transistor VT1 conduct. Thus, the external high-frequency power supply can form a loop through the switching circuit and the MOS transistor VT1 to ground, so that the external high-frequency power supply supplies power to the switching circuit and enables the welding device to work.

[0022] The switching circuit includes a switch P1 and a contactor M1. One end of the switch P1 is connected to the external high-frequency power supply. The other end of the switch P1 is connected to one end of the welding device 01. The other end of the welding device 01 is connected to the driving circuit. When the contactor M1 is energized, it drives the switch P1 to be normally closed. When the circuit is short-circuited, the driving circuit 1 loses power, causing the contactor M1 to disconnect. As a result, the switch P1 opens, and further disconnects the power supply from the welding device 01, thereby driving the welding device 01 to stop working.

[0023] The gate G of the MOS transistor VT1 is also grounded through a resistor R2. A resistor R3 is provided between the 3rd pin of the opto-coupler switch U1 and the external DC power supply. The function of the resistor R3 is to prevent the current in the opto-coupler switch U1 circuit from being too large, thus preventing damage to the circuit.

[0024] The working principle of the present utility model: By setting the driving circuit 1 for the external high-frequency driving power supply to drive the welding device 01 to work. If the welding device comes into contact with the ground and a short circuit occurs, the relay switch K1 closes, enabling the control end of the bidirectional thyristor V1 to be powered, making the bidirectional thyristor V1 conduct, thus opening the opto-coupler switch U1. The external DC power supply is grounded through the opto-coupler switch U1, causing the 3rd pin and the 4th pin of the opto-coupler switch U1 to be connected. This triggers the MOS transistor VT1 to disconnect, causing the high frequency to fail and the contactor M1 to disconnect, thereby stopping the welding device from working and protecting the workpiece. During normal operation, the opto-coupler switch U1 is disconnected, and the 3rd pin and the 4th pin of the opto-coupler switch U1 are in a disconnected state. The gate of the MOS transistor is connected through voltage division by the resistor R2 and the resistor R3, so that the external DC power supply supplies power to one end of the driving circuit, enabling the external high-frequency power supply to form a loop through the switching circuit and making the welding device in a working state. The circuit structure is simple. When the welding machine generates sparks, it can timely control the welding device to stop, preventing the generated sparks from damaging the workpiece.

Claims

1. A spark protection circuit for a high-frequency welding machine, characterized in that: It includes a drive circuit and a spark detection circuit. The spark detection circuit includes an optocoupler switch U1, a triac V1, and a relay switch K1. The first pin of the optocoupler switch U1 is connected to one end of the triac V1. The second pin of the optocoupler switch U1 is grounded. The third pin of the optocoupler switch U1 is connected to the other end of the drive circuit on the one hand and is connected to an external DC power supply on the other hand. The fourth pin of the optocoupler switch U1 is grounded. The other end of the triac V1 is connected to the power supply. The control end of the triac V1 is connected to one end of the relay switch K1, and the other end of the relay switch K1 is connected to the DC power supply.

2. The spark protection circuit of a high-frequency welding machine according to claim 1, wherein: The drive circuit includes an MOS transistor VT1 and a grid resistor R0 of an electron tube. The source S of the MOS transistor VT1 is grounded. The drain D of the MOS transistor VT1 is connected to one end of the grid resistor R0 of the electron tube. The gate G of the MOS transistor VT1 is connected to the third pin of the optocoupler switch and the external DC power supply. The other end of the grid resistor R0 of the electron tube is connected to the other end of the welding device, and one end of the welding device is connected to the switch circuit.

3. The spark protection circuit of a high-frequency welding machine according to claim 2, wherein: The switch circuit includes a switch P1 and a contactor M1. One end of the switch P1 is connected to an external high-frequency power supply. The other end of the switch P1 is connected to one end of the welding device, and the other end of the welding device is connected to the drive circuit. When the contactor M1 is energized, it drives the switch P1 to be normally closed.

4. The spark protection circuit of a high-frequency welding machine according to claim 2, characterized in that: The gate G of the MOS transistor VT1 is also grounded through a resistor R2.

5. The spark protection circuit of a high-frequency welding machine according to claim 1, wherein: A resistor R3 is provided between the third pin of the optocoupler switch U1 and the external DC power supply.

6. The spark protection circuit of a high-frequency welding machine according to claim 2, characterized in that: The resistance value of the grid resistor R0 of the electron tube is 3500 ohms.

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