This invention relates generally to a method of making valve bodies and the valve formed thereby, and more particularly to a method of making valve bodies for spool valves or the like.
Spool valves have cylindrical bores through the valve body with an axially shiftable central core or slide element movable therein to control the fluid flow from an inlet port to one or more outlet ports. Such spool valves have use as pilot valves, or the like, and are relatively simple and inexpensive to manufacture. However, because of the nature of construction of spool valves, their reliability over a long life is somewhat questionable. Spool valves of the type described above generally have O-rings inserted in grooves about the enlarged diameter portions of the slide element and these O-rings form the fluid seals between the respective chambers within the cylindrical bore. The inlet and outlet ports are formed by drilling or the like external passages from the outside of the spool valve to the interior thereof. By forming the inlet and outlet ports in this manner, a sharp peripheral edge is formed at the mating portions of the port orifice and the internal chamber wall of the cylindrical bore. By having these sharp ridges or edges about the periphery of the ports the O-rings passing over the ports tend to wear or be cut. Because spool valves are generally of relatively small construction, it is difficult, if not impossible, to eliminate these sharp edges by conventional manufacturing techniques used heretofore.