Studies on Grind-hardening with the Aid of Laser Conditioning of Grinding Wheel Surface

一般情况下，磨削热对工件会产生各种热损伤，如灼伤、裂纹、相变等。在本研究中，研磨作业被视为。一种称为磨削硬化的热处理工艺。这种新的热处理方法可以使钢的表层从奥氏体相转变为马氏体相。在几种进给速度下进行了外圆磨削试验，观察到了明显的硬化层，当进给速度大于40μm/S时，形成了硬度为700HV的马氏体组织，硬化层深度随进给速度的增加而增加。SCM435铬钼钢的插磨硬化层厚度约为0.16 mm。作为第二种方法，激光作为非接触式热修整…，可以去除磨削表面的氧化膜，使表面光滑且圆整度好更具工具的是青铜结合剂钻石砂轮。脉冲Nd：YAG光束法向对准，聚焦在砂轮表面，轴向进给直线工作台，该运动与砂轮转速、激光脉冲频率和脉冲宽度相协调，使激光覆盖整个砂轮表面。只有激光照射才能部分去除结合剂，熔化和汽化。为了有效地去除手部材料，有必要在激光照射点上喷气，以便在熔融的粘结剂再次凝固之前将其吹走，从而减少金刚石颗粒的微裂纹或石墨化等损伤。为了评价激光修整砂轮的磨削性能，对工程陶瓷进行了插入磨削试验，磨削力与普通修整砂轮基本相同，单位宽度的磨削量约为50mm~3/mm，这表明金刚石磨粒牢固地锚定在结合剂中而不会发生热劣化。因此，在适当的修整条件下，有效的激光修整是可望的。从实际应用的角度出发，设计了一种激光与空气射流同轴发射的一体化激光空气头。激光修整砂轮磨削时，磨削表面与常规修整砂轮基本相同。较少

In general, grinding heat canoes various types of thermal damage to the workpiece, such as burning, cracks, and phase transformation. In this study, the grinding operation is regarded as. a heat treatment process called Grind-hardening. This new heat treatment method enables the phase transformation from austenite to martensite in the surface layer of steels. The cylindrical grinding tests at several infeed rates are carried out A clear hardened layer is observed, where the martensitic structure is formed having the hardness of 700HV when the infeed rate is larger than 40μm/s. The depth of hardened layer increases as infeed rate increase. The hardened layer of approximately 0.16 mm is attained in plunge grinding of chrome-molybdenum steel SCM435. The oxidized film at the ground surface layer can be removed by the spark-out grinding and this process makes the surface smooth and good circularity of the workpiece.As the second approach, laser beam is used as a noncontact thermal dressing … More tool of a bronze bond diamond wheel. The pulsed-Nd:YAG laser beam is aligned in the normal direction and focused on the wheel surface The linear stage is fed in the axial direction and this motion is coordinated with the wheel rotation, laser pulse frequency and pulse duration so as to cover the overall wheel surface by laser beam The bond material is partially removed by laser irradiation only, in which melting and vaporizing take place. In order to efficiently remove the hand material, it is necessary to spray air jet on the laser irradiating spot so as to blow away the molten binder before it solidifies again less damage of diamond particles such as micro-cracks or graphitization is observed. In order to evaluate the grinding performance of a laser-dressed wheel, the plunge grinding tests of engineering ceramics are carried out The grinding forces are almost the same as the ordinary dressed wheel, and they are roughly kept constant up to 50 mm3/mm in stock removed per unit width of cut This shows that the diamond grits are anchored firmly in the bond without thermal deterioration_ Consequently, the effective laser dressing is expectable with the appropriate dressing conditions. For the purpose of practical use, the integrated laser-air head is designed in which laser beam and air jet are shot on the same axis. In grinding with the laser-dressed wheel, the grinding faces are almost the same as those for the conventionally dressed wheel. Less