## 6 Conclusions
\begin{tabular}{l l} \(h_{min}\) & the minimum oil film thickness \\ \(h_{t}\) & the maximum depth of the texture \\ \(h_{0}\) & the oil film thickness in the center of the elliptical contact area. \\ \(h_{i,j}\) & all grid points on the surface of the grinding wheel are characterized by a matrix \\ \(h(i,j)\) & the height of the cutting edge of the abrasive grain at the point (i, j) \\ \(h_{o},h_{p}\) & the oil film thickness distribution in the non-textured area and textured area on the \\ \(h_{o},h_{p}\) & raceway surface of the ball screws \\ \(i,j\) & the position of the abrasive grain in the circumferential and radial directions on the \\ \(L\) & the lead of the ball screw \\ \(L_{A},L_{B}\) & the friction arms of the screw and the nut raceway \\ \(L_{D}\) & the distance between the contact point of the ball and the bearing raceway and the \\  & rotation axis of the textured workpiece \\ \(L_{ij}\) & the arc length of the rotational movement of the abrasive cutting edge \\ \(M\) & the grit number \\ \(M_{1},M_{2}\) & the friction torques of the ball and bearing \\ \(M_{3}\) & the friction torque due to the coaxial error of the textured workpiece \\ \(M_{S}\) & the friction torque of the ball screws \\ \(M_{E}\) & the friction torque measured in the experiment \\ \(n_{b}\) & the number of working balls in a nut \\ \(n\) & the rotation speed of the grinding wheel \\ \(N_{D}\) & the number of balls in the bearing raceway \\ \(p\) & the bearing capacity of the oil film \\ \(p_{a},p_{f}\) & the bearing stress distribution of the asperity and the oil film in the elliptical contact area \\ \(p_{c}\) & the cavitation pressure of the oil film \\ \(P_{AS}^{H}\) & the parameter expression of the cross-sectional arc of the screw raceway at contact point \(A\) \\ \(P_{AS}^{S}\) & the parameter equation of the screw raceway in the coordinate system \(OXYZ\) \\ \(Q\) & the total normal contact force of the ball \\ \(Q_{a}\) & the normal force of the asperity contact \\ \(Q_{A}Q_{D}\) & the normal contact forces of the balls in the circular raceway and the bearing raceway \\ \(r_{b}\) & the radius of the ball \\ \(r_{t}\) & the radius of the texture \\ \(r_{s}\) & the radius of gyration of the cutting edge of the abrasive grain \\ \(r_{i,j}\) & the radial distance from the abrasive grain \(G_{ij}\) to the center of the grinding wheel \\ \(R_{x},R_{y}\) & the equivalent curvature radius in the \(x\) and \(y\) directions of the contact area \\ \(R(x,y)\) & the rough surface of the grinding raceway \\ \(R_{q}\) & the root mean square of the roughness of the screw raceway \\ \(t\) & the time taken for the grain \(G_{1}\) to rotate an angle \(\theta\) \\ \(T_{S}^{H}\) & the coordinate transformation matrix from the coordinate system \(OXYZ\) to the \\ \(T_{\mathbf{A}}^{H}\) & Frenet-Serret coordinate system \(O_{H}Hub\) of the helical trajectory of the ball center \\ \(T_{\mathbf{A}}^{A}\) & the coordinate transformation matrix from the Frenet-Serret coordinate system \\ \(O_{H}Hub\) to the contact coordinate system \(AX_{A}Y_{A}Z_{A}\) \\ \(u_{1},u_{2}\) & the linear velocities of the ball and raceway along the tangent direction of the spiral \\ \(u_{s}\) & the entrainment speed of the oil film \\ \(v_{s},v_{w}\) & the speeds of the grinding wheel and the screw \\ \(v_{uav},v_{s}\) & the feed speed of the workpiece and the circumferential speed of the grinding wheel \\ \(v_{s,b},v_{w,c}\) & the equivalent speeds of the grinding wheel and the screw \\ \(V_{\mathbf{S}}\) & the density of the wheel \\ \(V(x,y)\) & the elastic contact deformation in the elliptical contact area between the ball and \\  & the screw raceway \\ \(x_{int},y_{in}\) & the coordinates at the entrance of the contact area between the ball and the raceway \\ \(x_{out},y_{out}\) & the coordinates at the exit of the contact area between the ball and the raceway \\ \end{tabular}