Mold blank preparation
1. Workpiece material and blank
Die working parts are generally forged blanks, and their wire cutting processing is often carried out after quenching and tempering. Due to the influence of material hardenability, when removing metal in a large area and cutting off processing, the relative equilibrium state of residual stress in the material will be destroyed and deformation will occur, which will affect the processing accuracy, and even cause sudden cracking of the material in the cutting process.
2. Mold blank preparation procedure
The preparation process of die blank refers to all the processing processes before the on-line cutting of punch or die.
(1) Preparation process of female die
(2) Preparation process of punch
Clamping and adjustment of workpiece
1. Clamping of workpiece
When clamping the workpiece, it must be ensured that the cutting part of the workpiece is within the allowable range of longitudinal and transverse feed of the machine tool workbench to avoid exceeding the limit.
2. Adjustment of workpiece
When clamping the workpiece in the above way, it must also be adjusted with the alignment method, so that the positioning reference plane of the workpiece can be parallel to the workbench of the machine tool and the feeding direction X and y of the workbench, so as to ensure the relative position accuracy between the cut surface and the reference plane.
Selection and adjustment of electrode wire
1. Selection of electrode wire
The electrode wire shall have good conductivity and corrosion resistance, high tensile strength and uniform material. Commonly used electrode wires include molybdenum wire, tungsten wire, brass wire and cored wire.
2. Selection of threading hole and electrode wire cutting position.
The threading hole is the starting point of the electrode wire relative to the workpiece, and it is also the starting point of the program execution. It is generally selected at the reference point on the workpiece.
3. Selection of threading hole and electrode wire cutting position
The threading hole is the starting point of the electrode wire relative to the workpiece, and it is also the starting point of the program execution. It is generally selected at the reference point on the workpiece.
Adjustment of electrode wire position
Before wire cutting, the electrode wire should be adjusted to the starting coordinate position of cutting. The adjustment methods are as follows:
1. Visual inspection method: for workpieces with low processing requirements, when determining the relative position between the electrode wire and the workpiece benchmark, you can directly use visual inspection or observe with the help of a 2 ~ 8 times magnifying glass.
2. Spark method: move the workbench so that the reference plane of the workpiece gradually approaches the electrode wire. At the moment of spark, write down the corresponding coordinate value of the workbench, and then calculate the coordinate of the electrode wire center according to the discharge gap.
3. Automatic centering: it is to make the electrode wire automatically locate in the center of the workpiece hole. This method is to determine the center position of the electrode wire according to the short-circuit signal between the wire electrode and the workpiece.
Selection of process parameters
1. Selection of pulse parameters
In WEDM, transistor high-frequency pulse power supply is generally used, and the positive polarity processing is carried out with a single pulse parameter with small energy, narrow pulse width and high frequency.
2. Selection of pulse parameters
In WEDM, transistor high-frequency pulse power supply is generally used, and the positive polarity processing is carried out with a single pulse parameter with small energy, narrow pulse width and high frequency. When programming, first of all, it is required to calculate the vertical distance between the electrode wire center track and the machining figure, and divide the electrode wire center track into a single straight line or arc segment. After calculating the intersection coordinates of each segment, the programming is carried out step by step.
3. Selection of working fluid
Working fluid has a great influence on cutting speed, surface roughness, machining accuracy, etc., so it must be selected correctly during machining. Commonly used working fluids mainly include emulsion and deionized water.