Effects of process parameters on workpiece roundness in tangential-feed centerless grinding using a surface grinder

A new through-feed centerless grinding technique using a surface grinder

“…For the tangential-feed type, Xu et al (2010) created a 2-D grinding model by taking into account the elastic deformation of the machining system to clarify the workpiece rounding process and the effects of the process parameters on the workpiece roundness, and experimentally confirmed the simulation results. Further, Wu and Xu (2010) proposed a practical method for increasing material removal rate while workpiece final roundness is maintained at a high level in the tangential-feed type.…”

“…When the ultrasonic shoe is parallel to the grinding wheel axis, i.e. = 0 • (hereafter called tilt angle), the frictional force F f between the workpiece and ultrasonic shoe generated by the elliptic motion is only in the X-direction and used to control the workpiece rotational motion as that in tangential-feed type (Wu et al, 2005a;Xu et al, 2010) and in-feed type (Xu and Wu, 2011) centerless grinding, so that the peripheral speed of workpiece is the same as the bending vibration speed on the shoe upper end-face. However, in through-feed type centerless grinding the workpiece needs not only rotational motion but also through-feed motion along the Z-direction, thus the ultrasonic shoe is tilted at a small angle, i.e.…”

Sphere forming mechanisms in vibration-assisted ball centreless grinding

“…4b). It is obvious that the switch "off" time T off greatly affects the roundness of the cross-sections passing through x-axis [18], while the switch "on" time T on determines the whole ground area on spherical surface. To well-grind the whole ball surface, T off should be an integral number of the ball rotation period (1/n wz ) around z-aixs, while T on should be small enough.…”

“…This technique is based on the concept of the ultrasonic vibration-assisted centreless grinding of cylindrical components [16][17][18][19]. Two kinds of ultrasonic vibrations are applied to the ball, and by adjusting the directions of the vibrations, the ball can be controlled to rotate in two directions to achieve a full spherical surface grinding [14,15].…”

“…Once the required stock removal has been attained, the wheel feeding will stop followed by a dwell to allow "spark-out". During grinding, the ball's rotation around z-axis is controlled by the elliptic vibration from ultrasonic shoe, which is a typical centreless grinding operation for high precision roundness forming [16][17][18][19]. With an additional well-controlled rotational motion around x-axis by ultrasonic regulator, the whole surface of the ball can be well ground to generate a spherical shape.…”