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To enhance the effectiveness of jet polishing, ultrasonic coupled abrasive jet polishing (UC-AJP) was applied. Through high-frequency ultrasonic vibration, pressure lower than saturated vapor was generated in the jet. It made the jet medium cavitation; thus, cavitation-jet composite energy enhanced the material removal rate and reduced the roughness of the workpiece surface. Firstly, the principle of UC-AJP was analyzed, and a numerical model of UC-AJP was established according to the shear-stress transport (SST) k-ω turbulence model, Schnerr-Sauer cavitation model, and discrete phase model (DPM). Through the numerical calculation, the cavitation was enhanced with the increase of ultrasonic amplitude. When the amplitude reached 20 μm, the cavitation bubbles acted on the workpiece surface. Cavitation also increased the velocity and turbulent kinetic energy of the jet. Then, cavitation observation experiments were carried out; the results were consistent with the numerical simulation. Through the fixed-point polishing experiments, it was found that the erosion effect of UC-AJP on the workpiece was enhanced and then weakened. Through continuous polishing experiments, the surface of the workpiece was the smoothest after the polishing with amplitude 20 μm, the roughness decreased from 3.2 μm to 69 nm, and the speed of roughness reduction was also the fastest. [ABSTRACT FROM AUTHOR]

With the rapid development of modern industry, the surface of workpieces is becoming increasingly complex, and workpieces present the trend of small personalized batches. Robot polishing has become one of the required precision machining methods because of their excellent flexibility, ample working space, and strong maneuverability. Therefore, this paper reviews a series of precision machining methods based on robotic technology. First of all, the seven aspects of the operating principle of industrial robot polishing system like robot polishing force control technology, robot polishing trajectory planning, robot polishing path planning, robot teaching programming technology, robot polishing vibration control, multi-robot polishing control technology, and commercial robotic polishing systems, have been carried on in detailed by discussion and analysis. Secondly, researches on the basic architecture of the polishing robot are concluded by two aspects as researches on structure classification of the polishing robot and design of robot polishing end-effector. Finally, the study of robot polishing and future work are summarized. [ABSTRACT FROM AUTHOR]

A pneumatic wheel tool with reinforced aramid fiber is presented to finish irregular freeform surface with high hardness. Aramid fiber mainly is selected as a filler to achieve multi-dimension net distribution in polymer. In this case, the wheel can keep the outer abrasive particles more stable and decrease scratch damages of surface in the high-speed machining process. Based on the Halpin-Tsai formula, the orientation coefficient is brought in for the establishment of an elastic modulus prediction model of a fiber-reinforced pneumatic wheel. By ANSYS simulation, rules of stress and strain of pneumatic wheel with different volume ratios of fiber are given. It has been proved out that the fiber-reinforced method can overcome the defect of inner rubber deformation in the contact process. By mixed refining method, pneumatic wheels reinforced by aramid fiber are achieved. Multi-dimension net distribution of aramid fiber–reinforced polymer is observed in a microscopic view. Elastic modulus–predicted model is confirmed by drawing experiments. After that, aramid fiber–reinforced pneumatic wheel machining experiments are carried out. Results show that the fiber-reinforced method can improve surface roughness efficiently in the pneumatic wheel machining process and decrease scratch damages of the surface. [ABSTRACT FROM AUTHOR]

For improvement of finishing effect to the laser hardening mold's free-form surface with high hardness, double-layer elastic mechanics theory of pneumatic wheel based with softness consolidation abrasives (SCA) is analyzed. Under the annular stress around, ratio coefficient m of modulus of elasticity of abrasive layer to modulus of rubber layer and ratio coefficient n of thickness of abrasive layer to radius of stress have been bought in for establishing machining force model and deformation formula of double-layer elastic wheel. After that, a double-layer elastic model of the wheel has been established by ANSYS and the machining process has been simulated. Stress distribution and deformation rule are given by simulation. In the experiments, we use fiber to reinforce inner rubber layer and take binder to hold on abrasive particles. Microscopic analysis demonstrates that pneumatic wheel accords with the situation of double-layer elastic mechanic theory. Moreover, machining platform is established and empirical results show that pneumatic wheel can finish laser hardening mold's free-form surface efficiently. And conclusion shows pneumatic wheel with lower factor n can help to decrease R when it faces with concave surface and pneumatic wheel with higher factor n can improve machining efficiency to convex surface. [ABSTRACT FROM AUTHOR]

Pneumatic wheel based on softness consolidation abrasives (SCA) is presented as a key machining tool mainly for the improvement of finishing efficiency to free-form surface of laser-hardened molds. In this case, though its softness fits for machining to free-form surface, it cannot keep all abrasives within bounds strictly, but it makes abrasives experience creep deformation, which always leads to unstable machining characteristics. For research on the working rule of SCA, dynamic characteristics of abrasives need to be investigated. Firstly, soft ball model is brought into analysis of the normal and shear contact forces between two particles. By introducing damping coefficient, formulas on displacement and velocity of SCA are given for theory analysis of creep deformation. After that, force chains are established by simulation, which proves that SCA possesses more cutting force than free abrasives. At the same time, creep deformation of SCA is confirmed in accordance with the analysis of velocity of the single particle. Subsequently, combined with the modified Preston formula, comparative machining tests on material removal are carried on a laser-hardened free-form surface. Experimental results show that material removal rate of SCA is higher than that of free abrasive by approximately 34.35 %. Moreover, abrasive size is discussed as a key parameter respectively according to consolidation effects and surface roughness. The final conclusion is that SCA is certified to improve finishing efficiency for laser-hardened surfaces as well as suitable for machining free-form surfaces. [ABSTRACT FROM AUTHOR]

The high hardness and irregular characteristics of laser hardening free-form surface bring many problems into the finishing process. A new autofinishing method based on softness consolidation abrasives (SCA), oriented to laser hardening surface, is brought forward. Abrasives are consolidated on the rubber bonnet by the polymer binder, which have micromovement under the elastic restraint to form stress concentration for cutting. By the modification of coefficients and stress, the material removal model is given by the modified Preston equation. According to a series of simulation and practical experiments, the size of abrasive, hardness of abrasive, and hardness of surface were derived as important factors for the material removal. The empirical results showed that the modified Preston equation is propitious to avoid errors for calculation. Compared with free abrasive methods, it demonstrated that SCA can help to improve at least 13.6 % of efficiency. [ABSTRACT FROM AUTHOR]