Three-dimensional processing machine and a method of processing a workpiece

A method of processing a workpiece in three dimensions in which a spindle head which supports a tool is moved in x, y, and z directions, a pickup extends beyond a distal end of said tool in the z direction by a predetermined distance, when said pickup is in a lowest position and a pickup displacement detecting means is provided for detecting when said pickup has moved from said lowest position, said method comprising the steps of:

• moving the tool in the x and y directions to an initial position over the workpiece;
• lowering the tool in the z direction to an abutment position wherein the pickup abuts against the workpiece and is moved from said lowest position;
• measuring the distance between the initial position and the abutment position;
• repeating said moving and said lowering steps a predetermined number of times while varying said initial position;
• determining an imaginary surface contour of the workpiece based on the initial positions and the abutment positions to allow a predetermined depth from the surface of the workpiece to be obtained during processing of the workpiece with reference to said imaginary surface.

A method for processing a workpiece in a three-dimensional processing machine, comprising the steps of:

• moving a spindle head provided with a tool in an XY axis direction with respect to a surface of a table;
• lowering the spindle head in the Z axis direction perpendicular to said surface of the table;
• measuring the amount of descent of the spindle head from a standard position thereof and applying a predetermined depth processing to the workpiece with the tool;
• characterized in that the method further comprises the steps of moving the spindle head above a plurality of measuring points defined on the workpiece surface before processing, lowering the spindle head from said standard position until the lower end of said tool abuts on the workpiece, measuring the amount of descent from said standard position of the spindle head, determining imaginary surface data of the workpiece on the basis of the respective coordinate values of each of the measuring points, said coordinate values being constituted by XY position data, and an amount of descent of the spindle head in the Z direction, utilizing a Bezier curve or a B spline curve analysis, and controlling the movement of the spindle head, with the imaginary surface data as basis on the Z axis, during the predetermined depth processing on the workpiece (96).