September 19th, 2021
Principles and applications of laser heat treatment technology
Principle: Lasers have a very strong penetrating ability. When a metal surface is heated to a critical transformation temperature below its melting point, it is rapidly austenitized, then rapidly self-cooled and rapidly cooled, and the metal surface is rapidly strengthened. In other words, laser phase transformation curing. Laser heat treatment uses a high-power density laser beam to perform surface treatment of metals, and then performs surface modification treatments such as phase change hardening and surface alloying, resulting in surface composition, structure, and surface composition and structure that cannot be achieved by other surface quenching. It's a way to create performance. .. change.
Features: High-speed heating, high-speed cooling, the obtained structure is fine, high hardness, excellent wear resistance, hardened parts can obtain residual compressive stress exceeding 400kgf / mm2, which helps to improve fatigue performance. Control of multiple spot sizes is suitable for curing local areas such as tube holes, deep grooves, microzones, edges and cutting edges that cannot be processed by other heat treatment methods. Lasers Allows long-distance transmission, enabling a single laser on multiple worktables while using computer programming to control and control the laser heat treatment process for automation of the manufacturing process.
Applications: With the development of high power CO2 lasers, various forms of surfaces using many major automotive parts such as lasers, cylinder blocks, cylinder liners, crankshafts, camshafts, exhaust valves, valve seats, rocker arms, etc. The processing can be realized. Grooves on all aluminum piston rings can be treated with laser heat treatment. General Motors Corporation of the United States used a CO2 laser of over 12 kW to locally cure the inner wall of the steering gear housing, with a daily output of 30,000 sets, quadrupling work efficiency. China used high power CO2. The laser overhaul mileage to strengthen the inner wall of the automobile engine cylinder bore that can extend the engine is more than 150,000 kilometers; the wear resistance of the laser-treated cylinder block and cylinder liner hardening belt has been significantly improved and not yet. Hardened belts can increase oil storage and improve lubrication performance.
Cylinder block laser heat treatment equipment and production line laser coatings are similar to the laser alloying process, but with no additional alloys, the metal surface melts before cooling and solidifying, resulting in a fine, nearly uniform surface. It can be obtained. For some eutectic alloys, an amorphous surface layer with excellent corrosion resistance can be obtained. For example, a chrome-based surface coating on cast iron valve seats for diesel engines can provide a good stainless steel surface.
In 1997, Wuhan Huagong Laser designed and developed the "Cherokee" engine cylinder laser quenching production line. The production line used pioneering domestic and international technologies, including the use of new high-absorption materials and spray technology to replace traditional phosphate quenching. Quality The laser quenching system, including the main engine 2kW CO2 laser, precision numerically controlled quencher tool, and unmanned cooling system, is stable and reliable, and has excellent cylinder wall hole cleaning technology. Completed at once. Since the production line went into operation, about 100,000 engine blocks have been produced together with foreign advanced automobile manufacturing equipment, the surface hardness and wear resistance of the cylinder block have been improved, and the service life of the engine has been increased by 1 to 3 times. I did. ..
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