EDM Gap Control via Discharge Discrimination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In electric discharge machining, achieving precise control of the work gap to ensure consistent energy application and prevent leakage currents, which can lead to inadequate material removal and suboptimal surface roughness, especially when high-frequency alternating voltage is used.
Innovation Solution
An electric discharge machining apparatus that includes a power supply, motor, discharge counter, gap controller, and electric discharge discriminator to accurately count and control the number of electric discharges and detect inversions in gap voltage, allowing for precise servo control and discrimination of electric discharge occurrences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high frequency a.c. voltage is applied to the work gap to achieve μm order surface roughness, then surface finish quality is improved, but leakage current from microscopic waste causes incorrect servo control and insufficient material removal
Solution Approach 1:
The patent implements a feedback mechanism where the detected discharge occurrences are fed back to the servo controller to adjust the work gap size. The servo controller uses the discharge detection signal to determine whether to increase or decrease the gap, ensuring that sufficient material is removed while maintaining the desired surface roughness. This closed-loop feedback system resolves the contradiction by dynamically adjusting parameters based on actual discharge conditions.
Solution Approach 2:
The patent replaces the conventional mean gap voltage detection method with an electric discharge detection system. Instead of relying on voltage measurements that are affected by leakage current, the system directly detects discharge occurrences using a discharge detection circuit. This substitution eliminates the interference from leakage current and provides accurate feedback for servo control, resolving the contradiction between surface finish quality and material removal efficiency.
2Reliability
If mean gap voltage is used as servo control parameter, then work gap size is maintained at optimum value, but leakage current lowers non-load voltage causing incorrect servo control
Solution Approach 1:
The patent replaces the conventional mean gap voltage detection method with an electric discharge detection system. Instead of relying on voltage measurements that are affected by leakage current, the system directly detects discharge occurrences using a discharge detection circuit. This substitution eliminates the interference from leakage current and provides accurate feedback for servo control, resolving the contradiction between surface finish quality and material removal efficiency.
Solution Approach 2:
The patent introduces a discharge detection circuit as an intermediary between the work gap and the servo controller. This intermediary component directly detects discharge occurrences and provides a clean signal to the servo controller, bypassing the leakage current interference that affects voltage measurements. The discharge detection circuit acts as a mediator that translates the complex electrical conditions in the work gap into a reliable control signal.
3Use of energy by moving object
If a.c. voltage is applied to the work gap to generate repeated current pulses, then energy application efficiency is improved, but difficulty in accurately discriminating electric discharge occurrences increases
Solution Approach 1:
The patent introduces a discharge detection circuit as an intermediary between the work gap and the servo controller. This intermediary component directly detects discharge occurrences and provides a clean signal to the servo controller, bypassing the leakage current interference that affects voltage measurements. The discharge detection circuit acts as a mediator that translates the complex electrical conditions in the work gap into a reliable control signal.
Solution Approach 2:
The patent employs a detection method that identifies discharge occurrences through specific electrical characteristics (analogous to color changes). The discharge detection circuit looks for characteristic voltage changes or current patterns that indicate actual discharges versus leakage currents. By detecting these distinctive electrical 'signatures,' the system can accurately discriminate discharge occurrences even in the presence of a.c. voltage and leakage current.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables stable and precise electric discharge machining by accurately controlling the work gap, ensuring a sufficient number of electric discharges occur, thereby maintaining the desired surface roughness and dimensional precision.
Implementation Method 1
a power supply for applying a voltage to a work gap formed between the tool electrode and the workpiece to cause electric discharge
Data Source
AI summary
An electric discharge machining apparatus comprises a power supply (5) for applying a voltage to a work gap formed between a tool electrode (E) and the workpiece (W) and a motor (7) that moves the tool electrode relative to the workpiece. An electric discharges counter (45) counts a number of electric discharge occurrences within a specified period (Td1) and generating a first count. A gap controller (48) multiplies the first count by a gain to generate position command or speed command for motor drive. An inversion counter (42) counts a number of inversions of the gap voltage upwards or downwards within a second specified period (Td2) and generating a second count. An electric discharge discriminator (44) discriminates the occurrence of electric discharge when the second count reaches a set value.