| 摘要 |
The method involves a theoretical volume invoked for programming purposes. It is a two-stage process in which the upper face of a workpiece is machined, whilst the workpiece is held down flat by its base onto the milling machine table, followed by inversion and packing up, to replace lost material (or height) precisely, before machining the former base. Preferred features: The packing is formed by covering the surface initially machined by fixing a protective film (9) to it, or coating with parting agent. A hardening material (10) is cast onto it (9). A soft (plastic) spacer (7) is placed on top. This exceeds the thickness of the material machined away in the initial stage. It is precision-surfaced by milling to the required height (H) above the lower surface (112). Datums (11, 12) are defined and projected to the machine table (111, 112), to locate the principal axes after inversion. Screws, or preferably pegs fix and locate these axes, passing through extensions of the spacer (13, 15), the extensions being made of plastic resin. The workpiece is adhered to the milling table for fixation. The protective film is a plasticized adhesive.
|
