Roller taper grinding method for planetary roller screw mechanism

A roller taper grinding method for a planetary roller screw mechanism, comprising steps as follows

• step 1:
• determining basic parameters and a bearing capacity of a planetary roller screw mechanism to be machined;
• step 2:
• establishing deformation and force balance equations of the planetary roller screw mechanism according to the basic parameters and the bearing capacity of the planetary roller screw mechanism determined in step 1;
• step 3:
• iteratively computing an optimal grinding taper angle of roller grinding according to the deformation and force balance equations established in step 2;
• step 4:
• determining process parameters of roller grinding wherein the process parameters include an axial movement direction of a grinding wheel which is determined based on the optimal grinding taper angle computed in step 3;
• and
• step 5:
• grinding a roller taper of the planetary roller screw mechanism by a machine tool according to the process parameters determined in step 4, wherein the machine tool includes the grinding wheel;
• wherein the basic parameters of the planetary roller screw mechanism in step 1 comprise major diameters, nominal diameters, minor diameters, thread angles, helix angles, thread pitches, thread starts of a screw, a roller and a nut, an external diameter of the nut, an arc radius of the roller, number of rollers, and number of threads per roller,
• wherein the deformation and force balance equations of the planetary roller screw mechanism established in step 2 are:
• {
• P
• S
• +
• Δ
• ⁢
• l
• Si
• =
• P
• R
• +
• Δ
• ⁢
• l
• S
• ⁢
• Ri
• ±
• P
• R
• ⁢
• tan
• ⁢
• γ
• P
• N
• +
• Δ
• ⁢
• l
• Ni
• =
• P
• R
• +
• Δ
• ⁢
• l
• N
• ⁢
• Ri
• ±
• P
• R
• ⁢
• tan
• ⁢
• γ
• ⁢
• ∑
• i
• =
• 1
• N
• t
• ⁢
• F
• S
• ⁢
• Ri
• =
• F
• Z
• R
• ⁢
• ∑
• i
• =
• 1
• N
• t
• ⁢
• F
• N
• ⁢
• Ri
• =
• F
• Z
• R
• wherein PS, PR and PN are the thread pitches of the screw, the roller and the nut respectively;
• i is a thread number of the roller, i=1, 2, 3, . . . Nt, and Nt is the number of threads per roller;
• ΔlSi and ΔlNi are axial deformation at an ith segment of the screw and the nut respectively;
• ΔlSRi and ΔlNRi are axial deformation of the roller on a screw side and a nut side respectively;
• γ is a grinding taper angle of the roller;
• FSRi and FNRi are axial forces borne by an ith thread on the screw side and the nut side respectively;
• F is a load value of the planetary roller screw mechanism;
• ZR is the number of rollers;
• and ± indicates a tension and compression state of the screw or the nut, + indicates tension, and − indicates compression.