Recently, various machining processes such as mechanical nontraditional machining, electric nontraditional machining, and chemical nontraditional machining have been studied in various ways to perform surface finishing on mechanical parts and increase their durability.
Examples of mechanical nontraditional machining include sandblasting and shot peening, both of which improve fatigue strength and surface hardness by generating work-hardening on the surface of a workpiece. In particular, shot peening can not only increase design ability by improving strength of a material, but maintain high toughness at the center portion of the material, so it is very useful for parts in a mechanical structure that receive fatigue loads, and is very important particularly for improving fatigue strength and lifespan.
In comparison to heat treatment or other machining methods, an advantage of shot peening is that it is possible to be performed without using a large energy source and thus pollution due to consumption of fuel is reduced. Further, strength increases after shot peening, so weight decreases, energy is saved, and air pollution is prevented.
Shot peening is used throughout industry including mechanical, aerial, automotive, shipbuilding, and civil engineering and construction fields, and particularly, the size, strength, and safety of products have been improved and the weight of products has been decreased with development of the technology, so shot peening is applied to various and wide fields.
Further, shot peening is particularly useful for increasing fatigue lifespan and fatigue strength of a coil spring, a leaf spring, a gear, a crankshaft, a connecting rod, an axle shaft, a universal joint, a piston, a cylinder block, a crank case, a torsion bar, a chain link, a milling cutter, a drill, a high-pressure steel pipe, a high-pressure container, jet engine blades, and blades of a helicopter. Furthermore, shot peening is useful for a notch of a part, a key groove, a welded portion, corrosion fatigue portion, a portion under high stress, a surface of a part after machining, a surface after grinding, a decarbonized portion after heat treatment, a friction portion, a distorted portion, and a surface after discharge machining.
Soft steel, hard steel, tooled steel, steel for a structures, spring steel, duralumin, an aluminum alloy, stainless steel, zinc, and emery are generally used for the material of shot balls.
Manufacturing methods for a steel shot ball include a casting method and a method that uses a cut wire, and both are used to create a stronger paint adhesion quality on a metal surface by making the metal surface rough using metallic particles like sand grains.
Shot and grit are types of shot peening balls generally used in industries using metal as a raw material, such as automotive, constructing, shipbuilding, forging, and steel industries, and are needed to satisfy various shapes and properties of metals. Accordingly, the inventor(s) has proposed a “Shaping apparatus for shot” and manufactured a shot in Korean Patent No. 10-0524536.
However, according to the shaping apparatus for shot, material is accumulated between projection sides in projection for rounding and there is a problem of inaccurate sorting and loss of shot in the process of sorting complete shot balls in accordance with diameters thereof.
Further, dust cannot be completely collected due to overload in the apparatus, so there is a need for an apparatus for forming shot equipped with a device that can strongly suppress generation of dust.