A pulsating discharge method

Abstract

The application discloses a pulsating discharge method, comprising the following steps: in the electric spark machining, for each pulse output during the machining, an additional higher frequency pulse is superimposed, and the discharge current presents a pulsating state within a pulse width. The method can produce a changing magnetic field through the pulsating current in the electric spark machining, the changing magnetic field can produce a periodically changing force on the electrons in the discharge channel, the electrons in the plasma in the discharge channel can swing back and forth on the workpiece, the acting area is large, the energy is dispersed, the electric erosion pit is large and shallow, the high efficiency can be maintained, the better surface roughness and the shallower heat affected layer can be obtained, the efficiency and quality can be achieved, the method has the advantages of simplicity, reliability and stability, and does not affect the actual machining effect.

Description

Technical Field

[0001] This invention relates to the field of electrical discharge machining technology, specifically to a pulsed discharge method. Background Technology

[0002] Electrical discharge machining (EDM) is a machining method that uses electrical discharge between a workpiece and a tool electrode to generate high temperatures that melt and vaporize the material. It has advantages such as being unaffected by the hardness of the workpiece material and having low machining force, and is widely used in aerospace, weaponry, and civilian fields.

[0003] The characteristics of electrical discharge machining (EDM) dictate that efficiency and quality are mutually exclusive. High discharge energy results in high efficiency but also large craters, poor surface roughness, and a tendency to develop microcracks. Conversely, low discharge energy produces good surface quality but low efficiency. To balance efficiency and quality in EDM, existing technologies employ mixed-powder EDM, dispersing a single discharge point into multiple points for simultaneous discharge. This maintains the same total energy and total material removal, transforming the large craters removed by a single discharge into smaller craters from multiple discharge points, thus improving surface quality and reducing the heat-affected layer. However, in mixed-powder EDM, the significant density difference between the powder and liquid leads to sedimentation and clumping, negatively impacting the actual processing results. Therefore, a simple, reliable, and effective pulsed discharge method that achieves both efficiency and quality without compromising the final processing outcome is urgently needed. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned problems and provide a pulsed discharge method that can achieve both efficiency and quality in electrical discharge machining. This method is simple, reliable, and stable, and does not affect the actual machining effect.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A pulsed discharge method includes the following steps:

[0007] In electrical discharge machining, for each pulse output during machining, an additional pulse of a higher frequency is superimposed, so that the discharge current pulsates within a pulse width.

[0008] In a preferred embodiment of the present invention, the pulsating change of the discharge current is achieved by adjusting the periodic change of the current-limiting resistor in the pulsating discharge circuit.

[0009] Preferably, the specific steps for achieving the pulsating change of the discharge current by adjusting the periodic change of the current-limiting resistor in the pulsating discharge circuit are as follows:

[0010] The pulsating change of the discharge current is achieved by connecting a controllable periodically switching resistor branch in parallel with the current-limiting resistor in the pulsating discharge circuit.

[0011] Preferably, the pulsating discharge circuit includes a power supply, a circuit switch, a current-limiting resistor, an electrical discharge machining (EDM) unit, and a switchable resistor branch; wherein the power supply, circuit switch, current-limiting resistor, and EDM unit are connected in series; the resistor branch is connected in parallel with the current-limiting resistor; the resistor branch includes a branch switch and an adjustable resistor connected in series. In the above-mentioned pulsating discharge circuit, a switchable resistor branch is connected in parallel with the current-limiting resistor in the pulsating discharge circuit, and the pulsating change of the discharge current is achieved by periodically switching the adjustable resistor in the resistor branch on and off.

[0012] Preferably, the specific steps for achieving the pulsating change of the discharge current by adjusting the periodic change of the current-limiting resistor in the pulsating discharge circuit are as follows:

[0013] The pulsating change of the discharge current is achieved by periodically switching two current-limiting resistors with different resistance values ​​back and forth in the pulsating discharge circuit.

[0014] Preferably, the pulsating discharge circuit includes a power supply, a resistive pulsating circuit, and an electrical discharge machining (EDM) unit; the power supply, pulsating circuit, and EDM unit are connected in series; the pulsating circuit includes a first resistor branch and a second resistor branch connected in parallel; the first resistor branch includes a first branch switching transistor and a first current-limiting resistor connected in series; the second resistor branch includes a second branch switching transistor and a second current-limiting resistor connected in series; the two current-limiting resistors are the first current-limiting resistor and the second current-limiting resistor, respectively, and the resistance values ​​of the first current-limiting resistor and the second current-limiting resistor are different. In the above-mentioned pulsating discharge circuit, by connecting a first current-limiting resistor and a second current-limiting resistor with different resistance values ​​in parallel, the on and off states of the first current-limiting resistor and the second current-limiting resistor are periodically switched back and forth, thereby realizing the pulsating change of the discharge current.

[0015] Preferably, the pulsating change of the discharge current is achieved by periodically switching the high-voltage power supply and the low-voltage power supply alternately on and off in the pulsating discharge circuit.

[0016] Preferably, the pulsating discharge circuit includes a power pulsating circuit, a current-limiting resistor, and an electrical discharge machining (EDM) unit. The power pulsating circuit, current-limiting resistor, and EDM unit are connected in series. The power pulsating circuit includes a first power supply branch and a second power supply branch connected in parallel. The first power supply branch includes a first branch switch, a low-voltage power supply, and a first diode connected in series. The second power supply branch includes a second branch switch, a high-voltage power supply, and a second diode connected in series. In the above-mentioned pulsating discharge circuit, by periodically switching the high-voltage power supply and the low-voltage power supply on and off by connecting them in parallel, the pulsating change of the discharge current is achieved.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] The pulsed discharge method in this invention superimposes a higher-frequency pulse onto the normal electrical discharge machining pulse (the original pulse). That is, within one pulse width, the discharge current fluctuates instead of remaining constant. This changing current generates a changing magnetic field, which exerts a varying force on the electrons in the discharge channel. This causes the electron beam within the plasma in the discharge channel within the machining gap to sweep back and forth across the workpiece surface, increasing the effective area and resulting in larger, shallower craters from the explosion. Therefore, while maintaining the original machining efficiency, surface roughness is improved and the heat-affected zone is reduced. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structural principle and a diagram of the discharge current variation of the first specific embodiment of the pulsating discharge circuit in this invention.

[0020] Figure 2 This is a schematic diagram of the structural principle and a diagram showing the change in discharge current of a second specific embodiment of the pulsating discharge circuit in this invention.

[0021] Figure 3 A schematic diagram of the structural principle and a diagram of the discharge current variation of the third specific embodiment of the pulsating discharge circuit in this invention. Detailed Implementation

[0022] To enable those skilled in the art to fully understand the technical solutions of the present invention, the present invention will be further described below in conjunction with embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0023] Example 1

[0024] This embodiment provides a pulsed discharge method, including the following steps:

[0025] In electrical discharge machining, for each pulse output during machining, an additional pulse of a higher frequency is superimposed, so that the discharge current pulsates within a pulse width.

[0026] The pulsed discharge method in this embodiment adds a higher frequency pulse to the normal electrical discharge machining pulse (the original pulse), that is, it varies pulsatingly within a pulse width instead of the original constant value. This pulsating current generates a changing magnetic field, which exerts a periodically changing force on the electrons in the discharge channel. Electrons in the plasma within the discharge channel sweep back and forth across the workpiece 1, resulting in a large effective area, dispersed energy, and large but shallow electro-erosion pits. While maintaining high efficiency, it achieves better surface roughness and a shallower heat-affected layer, achieving both efficiency and quality. It has the advantages of simplicity, reliability, and stability, and does not affect the actual processing effect.

[0027] See Figure 1 The pulsed discharge method is implemented through a pulsed discharge circuit. Specifically, the pulsed change of the discharge current is achieved by periodically adjusting the current-limiting resistor in the pulsed discharge circuit.

[0028] See Figure 1 The specific steps to achieve the pulsating change of discharge current by adjusting the periodic change of the current-limiting resistor in the pulsating discharge circuit are as follows: the pulsating change of discharge current is achieved by connecting a controllable periodically switching resistor branch in parallel with the current-limiting resistor 3 in the pulsating discharge circuit.

[0029] See Figure 1 The pulsating discharge circuit includes a power supply 10, a circuit switch 7, a current-limiting resistor 3, an electrical discharge machining (EDM) unit, and a switchable resistor branch. The power supply 10, circuit switch 7, current-limiting resistor 3, and EDM unit are connected in series. The resistor branch is connected in parallel with the current-limiting resistor 3. The resistor branch includes a branch switch 5 connected in series and an adjustable resistor 4. In the above pulsating discharge circuit, a switchable resistor branch is connected in parallel with the current-limiting resistor 3. The pulsating change of the discharge current is achieved by periodically switching the adjustable resistor 4 in the resistor branch on and off.

[0030] See Figure 1 The electrical discharge machining unit includes a workpiece 1 and an electrode 2, with a discharge gap between the workpiece 1 and the electrode 2; the positive terminal of the power supply 10 is connected to the workpiece 1, and the current limiting resistor 3 and the adjustable resistor 4 are both connected to the electrode 2; one end of the circuit switch tube 7 is connected to the negative terminal of the power supply 10, and the other end is connected to the branch switch tube 5 and the current limiting resistor 3 respectively.

[0031] See Figure 1 The circuit switch 7 is switched on and off at a frequency of f1. During the on-time of the circuit switch 7, the voltage source provides the basic discharge current I1 through the current limiting resistor 3. The branch switch 5 is switched on and off at a frequency of f2 higher than f1, generating a pulsating current I2 with a pulse frequency of f2 in the resistor branch. I1 and I2 are superimposed to form the pulsating discharge current I0.

[0032] See Figure 1 R c1 Represented as current-limiting resistor 3, R c2 Q1 is represented as adjustable resistor 4, Q2 is represented as branch switch transistor 5, Q1 is represented as loop switch transistor 7, and U is represented as power supply 10.

[0033] Example 2

[0034] See Figure 2The pulsating discharge circuit in this embodiment is different from the pulsating discharge circuit in Embodiment 1, and the adjustment method is also different. The specific steps to achieve the pulsating change of the discharge current by adjusting the periodic change of the current limiting resistor in the pulsating discharge circuit are as follows: the pulsating change of the discharge current is achieved by periodically switching back and forth two current limiting resistors with different resistance values ​​in the pulsating discharge circuit.

[0035] See Figure 2 The pulsating discharge circuit includes a power supply 10, a resistor pulsating circuit, and an electrical discharge machining (EDM) unit. The power supply 10, the pulsating circuit, and the EDM unit are connected in series. The pulsating circuit includes a first resistor branch and a second resistor branch connected in parallel. The first resistor branch includes a first branch switch 6 and a first current-limiting resistor 3 connected in series. The second resistor branch includes a second branch switch 5 and a second current-limiting resistor 4 connected in series. The two current-limiting resistors are the first current-limiting resistor 3 and the second current-limiting resistor 4, respectively, and their resistance values ​​are different. In the above pulsating discharge circuit, by connecting the first current-limiting resistor 3 and the second current-limiting resistor 4 with different resistance values ​​in parallel, the on / off state of the first current-limiting resistor 3 and the second current-limiting resistor 4 is periodically switched back and forth, achieving pulsating changes in the discharge current.

[0036] See Figure 2 The electrical discharge machining (EDM) unit includes a workpiece 1 and an electrode 2, with a discharge gap between the workpiece 1 and the electrode 2. The positive terminal of the power supply 10 is connected to the workpiece 1, and the electrode 2 is connected to a first current-limiting resistor 3 and a second current-limiting resistor 4. The negative terminal of the power supply 10 is connected to a first branch switch 6 and a second branch switch 5. By alternately turning on the first branch switch 6 and the second branch switch 5, the discharge current provided by the first resistor branch is I1 when the first branch switch 6 is on, and the discharge current provided by the second resistor branch is I2 when the second branch switch 5 is on. Within one pulse width, I1 and I2 continuously switch to form a pulsating discharge current I0.

[0037] See Figure 2 R c1 Represented as the first current-limiting resistor 3, R c2 4 represents the second current-limiting resistor, 5 represents the second branch switch transistor, 6 represents the first branch switch transistor, and 10 represents the power supply.

[0038] Example 3

[0039] See Figure 3 The pulsating discharge circuit in this embodiment is different from the pulsating discharge circuit in embodiment 1. In this embodiment, the pulsating discharge circuit achieves the pulsating change of the discharge current by using two power supplies, high voltage power supply 11 and low voltage power supply 10, to alternately and periodically switch on and off.

[0040] See Figure 3 The pulsating discharge circuit includes a power pulsating circuit, a current-limiting resistor 3, and an electrical discharge machining (EDM) unit. The power pulsating circuit, current-limiting resistor 3, and EDM unit are connected in series. The power pulsating circuit includes a first power supply branch and a second power supply branch connected in parallel. The first power supply branch includes a first branch switch 12, a low-voltage power supply 10, and a first diode 8 connected in series. The second power supply branch includes a second branch switch 13, a high-voltage power supply 11, and a second diode 9 connected in series. In the above pulsating discharge circuit, by periodically switching the high-voltage power supply 11 and the low-voltage power supply 10 on and off, the pulsating change of the discharge current is achieved.

[0041] See Figure 3 The electrical discharge machining (EDM) unit includes a workpiece 1 and an electrode 2, with a discharge gap between the workpiece 1 and the electrode 2. The positive terminal of the low-voltage power supply 10 is connected to a first diode 8, and the negative terminal is connected to a first branch switch 12. The positive terminal of the high-voltage power supply 11 is connected to a second diode 9, and the negative terminal is connected to a second branch switch 13. The workpiece 1 is connected to both the first diode 8 and the second diode 9. One end of the current-limiting resistor 3 is connected to both the first branch switch 12 and the second branch switch 13, and the other end of the current-limiting resistor 3 is connected to the electrode 2.

[0042] See Figure 3 In this embodiment, voltage regulation is used to achieve pulsating discharge. The low-voltage power supply 10 is a low-voltage DC source, and the high-voltage power supply 11 is a high-voltage DC power supply 10. The low-voltage power supply 10 is connected in series with a first diode 8, and the high-voltage power supply 11 is connected in series with a second diode 9 to prevent the high-voltage power supply 11 from charging the low-voltage power supply 10. The first branch switch 12 is switched on and off at a frequency f1. The low-voltage power supply 10 provides a relatively small basic discharge current I1 at a frequency of f1. The second branch switch 13 is switched on and off at a frequency f2 higher than f1. The high-voltage power supply 11 generates a higher pulsating current I2 at a frequency of f2. I1 and I2 are superimposed to form the pulsating discharge current I0.

[0043] See Figure 3 Because the discharge current I0 is pulsating, a changing magnetic field is generated. The changing magnetic field exerts a periodically changing force on the electrons moving in the discharge channel. The plasma sweeps back and forth on the surface of the workpiece 1, expanding the area of ​​electro-erosion. Under the condition that the processing efficiency remains basically unchanged, the electro-erosion pits become shallower and the heat-affected layer becomes thinner, thus conveniently and reliably achieving efficient and high-quality processing results.

[0044] See Figure 3 R cQ1 represents the current-limiting resistor 3, Q2 represents the second branch switch transistor 13, Q1 represents the first branch switch transistor 12, U1 represents the low-voltage power supply 10, U2 represents the high-voltage power supply 11, D2 represents the second diode 9, and D1 represents the first diode 8.

[0045] The above are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above content. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A pulsed discharge method, characterized in that, Includes the following steps: In electrical discharge machining, the pulsating change of the discharge current is achieved by adjusting the periodic change of the current-limiting resistor in the pulsating discharge circuit. The specific steps to achieve the pulsating change of the discharge current by adjusting the periodic change of the current-limiting resistor in the pulsating discharge circuit are as follows: The pulsating change of the discharge current is achieved by periodically switching two current-limiting resistors with different resistance values ​​back and forth in the pulsating discharge circuit. The pulsed discharge circuit includes a power supply, a resistor pulsed circuit, and an electrical discharge machining (EDM) unit; the power supply, pulsed circuit, and EDM unit are connected in series; the pulsed circuit includes a first resistor branch and a second resistor branch connected in parallel; the first resistor branch includes a first branch switch transistor and a first current-limiting resistor connected in series; the second resistor branch includes a second branch switch transistor and a second current-limiting resistor connected in series; the two current-limiting resistors are the first current-limiting resistor and the second current-limiting resistor, respectively, and the resistance values ​​of the first current-limiting resistor and the second current-limiting resistor are different; By alternately turning on the first branch switch and the second branch switch, the discharge current provided by the first resistor branch is I1 when the first branch switch is turned on, and the discharge current provided by the second resistor branch is I2 when the second branch switch is turned on. Within one pulse width, I1 and I2 continuously switch to form a pulsating discharge current I0.

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