67results about How to "Eliminate residual internal stress" patented technology

The invention discloses a method with functions of preheating and postheating for forming crack-free coating with high efficiency by a three-light-beam laser-cladding technique. The method comprises the following steps of: splitting a laser beam emitted by an Nd: YAG laser into two laser beams by using a laser beam splitter, namely a preheating laser beam for preheating the surface of a base material and a postheating laser beam for postheating the formed coating; then blowing alloy powder into a molten pool which is formed by focusing a laser beam emitted by a CO2 laser and acting the focused laser beam on the surface of the base material by using a powder nozzle, wherein after the CO2 laser beam moves away, a molten layer is cured and crystallized quickly to form the coating; and postheating the formed coating by adopting the postheating laser beam. The method has the advantages that: (1) the dilution rate of the coating is low and adjustable, and the coating is metallurgically combined with the base material, so the base material has a small thermal influence area and is deformation-free and crack-free; (2) residual inner stress in the coating can be eliminated effectively, a tissue can be improved, and the coating has high abrasion resistance, high corrosion resistance, high anti-cracking performance and high thermal shock resistance; and (3) relative to the processing efficiency in the conventional laser cladding technology, the processing efficiency in the method can be improved by 50 times to the maximum extent, so the processing cost is reduced greatly, and a large-scale industrialized application potential is realized.

The invention discloses a polypropylene toughening modifying agent and a polypropylene modified product thereof. The polypropylene toughening modifying agent comprises the following components: 15-50 wt percent of polyethylene, 15-50 wt percent of polypropylene, 20-55 wt percent of ethylene / octene copolymer (POE), 0.1-2.0 wt percent of initiator and 0.05-1.0 wt percent of antioxidant. A polypropylene modified pipe and an injection molding product which are produced by adopting the polypropylene toughening modifying agent are produced by the steps as follows: 2-15 wt percent of the polypropylene toughening modifying agent and 85-98 wt percent of polypropylene resin are physically mixed, a proper amount of coloring agent is added, the polypropylene modified pipe is extruded on a single-screw pipe extruder, and the polypropylene modified product is injected-molded on an injection molding machine. The polypropylene modified product has an impact strength which is increased by 28-34.5 percent, the melting temperature which is raised by 1.5-1.8 DEG C, and the crystallinity which is increased by 26.7-35.2 percent. According to the invention, the slow secondary crystallization of the polypropylene modified product in a post-stage storage process can be effectively reduced, and the residual internal stress of the polypropylene modified product is greatly eliminated.

A method for straightening the deformed frame of car includes such steps as detaching, straightening the deformed parts, repairing the damaged parts by welding and redrilling, ageing, assembling with screw bolts and nuts, and cold rivetting by using rivets to replace the screw bolts and nuts. Its apparatus is also disclosed.