Study On Laser Re-manufacturing Straightening Technology Of Shaft Part

With the urgently needed of the sustainable development of a country, re-manufacturing technology has been given increasing attention. Re-manufacturing technology is a useful weapon in eliminating its environmental pollution and reducing the resource waste. Shaft parts are very important components in mechanical assembly. The annual output of the shaft parts in our country is about ten hundred million. Roughly70%shafts among them need to be straightened. How to combinate the re-manufacturing technology and shaft straightening together is the focus of attention. Since the1980’s, laser cladding and laser hardening technology have been widely used both at home and abroad.It has been applied in many industrial fields especially for re-manufacturing of mechanical parts. On this basis, laser re-manufacturing technology has been used for shaft straightening in this paper. The feasibility of laser technology for shaft straightening is proven by means of feasibility test. The effects of technological parameters on the shaft straightening degree is analyzed by means of technological parameter trail of laser cladding. Temperature gradient mechanism is preliminary verified by means of the collection and analysis of temperature data adjacent to cladding area. Transient temperature field and stress distribution and corresponding deform are obtained by use of the finite element numerical simulation method, which utilize the ANSYS software. Temperature gradient mechanism is further discussed. Successful completions of the engineering projects effectively prove that laser re-manufacturing straightening have extensively applied foreground. And finally this technology is introduced and extended intuitively and simply to the enterprise which in need. The main works involved as follows:(1) Laser hardening and laser cladding both can be used for shaft straightening. Stepped shaft is bent towards the laser beam. It confirm the feasibility of the project approval and the correctness of the analysis The eccentricity which is straightened by laser hardening is below0.09mm. The eccentricity which is straightened by laser cladding is larger than0.1mm. So if the shaft’s eccentricity is below0.1mm, laser hardening technology can be chosen. Or else laser cladding can be chosen.(2) In laser cladding straightening technology, center angle corresponding to the bending zone β has been chosen as the parameter to measure the bending degree. The technological parameters which have great effect on the bending degree are laser axial angles a and number of cladding layer n. When the axis angle a is smaller than90°, the shaft bending degree tanβ is directly proportional to the cladding area and when the angle a is greater than90°, the shaft bending degree tanβ is decreased. So theoretically the maximum of axial angles a is90°. The shaft bending degree tanβ is directly proportional to the number of cladding layer n. In practice the technological parameters is chosen according to the bending degree and the request of the client.(3) Temperature field simulation of the laser cladding straightening is obtained by use of the ANSYS finite element software. The temperature in cladding area is highest. The temperature in transition region is middle and the temperature in shaft is lowest. Temperature gradient is appeared along the length of the shaft and along the cross section of the shaft. Temperature field at any time are similar. That is the temperature in laser spot is highest and decreased outward centered on the laser spot. The isothermals are approximate ellipse. The center is the laser spot. The temperature of the location where the laser spot pass through has rapid variation, quick temperature rising and quick drop. Put up the typical sharp quenching and snap heating characteristic.(4) Thermal stress distribution simulation of the laser cladding straightening is obtained by use of the ANSYS finite element software. The thermal stress in cladding area is highest. The thermal stress distribution present dynamical change. Sometimes tensile stress and sometimes compressive stress. But there is always compressive stress in the center of the laser spot. So it can’t be considered that cladding area present compressive stress during laser cladding. Cladding area present tensile stress in X, Y and Z direction during cooling process. It is caused by cooling shrinkage of cladding area.(5) According to the trail data, either in laser cladding process or in cooling process, temperature in different points in circumference is different. There is temperature gradient along the cross section of the shaft. Temperature gradient makes the deformation at different location unevenness and then causes the thermal stress. Temperature gradient mechanism is preliminary verification. In temperature field simulation and thermal stress distribution simulation, temperature gradients appear along the length direction and along the cross section clearly which cause the thermal stress and shaft deformation. Temperature gradient mechanism is further verified.(6) The reasonable process route has been set during the engineering projects. Successful completions of the engineering projects effectively prove that laser cladding straightening is feasible. After the bending degree is measured and the bending direction is ensured and the specific analysis is done, the reasonable laser technology is arranged to straighten the shaft. It brings enormous economic benefit and has extensively applied foreground.