(1) Selection of pulse parameters
In wire cutting machining, transistor high-frequency pulse power supply is generally used, and positive polarity machining is carried out using pulse parameters with small single pulse, narrow pulse width, and high frequency. During processing, the pulse parameters that can be changed mainly include current peak, pulse width, pulse interval, no-load voltage, and discharge current. When requesting a better surface roughness, the selected electrical parameters should be small; If higher cutting speed is required, larger pulse parameters should be selected, but the increase in machining current is limited by chip removal conditions and electrode wire cross-sectional area. Excessive current can easily cause wire breakage.
(2) Determination of process dimensions
During wire cutting, in order to obtain the required machining size, a certain distance must be maintained between the electrode wire and the machining pattern. When programming, it is first required to determine the vertical distance △ R (gap compensation distance) between the electrode wire trajectory and the machining shape, and divide the electrode wire trajectory into a single straight line or arc segment. After calculating the intersection coordinates of each segment, programming is gradually carried out. The specific steps are as follows:
1) Set machining coordinate system
Determine the machining coordinate system based on the clamping situation and cutting direction of the workpiece. To simplify calculations, it is advisable to select the symmetrical axis of the graph as the coordinate axis as much as possible.
2) Compensation calculation
According to the selected electrode wire radius r, the discharge gap δ, and the single-sided matching gap Z/2 of the convex and concave molds, the compensation distance △ R1 for processing the concave mold is r+δ
3) Divide the electrode wire trajectory into smooth straight lines and single arc lines, and calculate the coordinate values of the intersection points of each line segment based on the average size of the hole or punch.
(3) Selection of working fluid
The working fluid has a significant impact on cutting speed, surface roughness, machining accuracy, etc. It is necessary to select and match it correctly during machining. The commonly used working fluids include emulsions and water-based solutions. The working medium can be tap water, distilled water, high-purity water, and magnetized water.
