SU1357637A1 - Ball bearing screw mechanism - Google Patents

Abstract

BACKGROUND OF THE INVENTION The invention relates to ball bearing precision screw transmissions. The purpose of the invention is to increase / 1 L / niv accuracy and transmission capacity due to the direct contact of the balls with the screw groove at a large angle of coverage. Ball bearings 4 without inner rings are installed in housing I at an angle to the axis of the screw 2 equal to the angle of lift of the screw grooves 3 , and with multidirectional eccentricity. The bearings 4 are raised by the set screws 8 within the elastic deformation, as a result of which the angle of coverage of the balls 5 of the screw 2 increases. When the screw is screwed 2, the balls 5 are rotated along the helical groove 3, and the body I makes translational motion. Zil. (L has eaten O5 oo Figure 1

Description

The invention relates to mechanical engineering, in particular to screw gears, and can be applied in precision machine-tool construction, as well as in devices that require the conversion of rotational motion into a high-precision translational,

The purpose of the invention is to increase the accuracy and load capacity of the transmission due to the direct contact of the balls with the helical groove. screws at a higher angle of capture.

Figure 1 shows the structural scheme of the mechanism; figure 2 - section aa in figure 1; on fig.Z - installation diagram of ball bearings along the axis of the screw.

The mechanism includes a housing 1, a screw 2 housed therein with a screw groove 3 cut into it, and ball bearings 4, balls 5 of which are housed in cages 6 and designed to interact directly with screw grooves 3 of screw 2. Ball bearings 4 are mounted with a multi-directional eccentricity relative to screw 2 and at an angle to its axis equal to the angle of elevation of the screw groove 3.

The housing 1 has threaded holes 7, the axes of which form between them a central angle oi. . Depending on the number of balls 5 in ball bearings 4, the angle about has the following meanings: for nine balls 46-120, and for sixteen balls 80-157 °.

The holes 7 accommodate set screws 8, which ensure the eccentricity of the ball bearings 4 relative to the screw 3 and increase: the angle tji of the coverage of the balls 5 of the screw 3 due to the elastic deformation of the outer rings of the ball bearings 4. To install the ball bearings 4 with a step equal to or proportional to the pitch of the helical groove 3 , spacers 9 are used. Vel: Ningina deformations of outer rings of ball bearings 4 90 °

for angle 0 mule

is determined by fory 0.3 (R - R, d),.

R, is the inner radius of the screw

grooves 3 on screw 2; R, 2 is the radius of the treadmill of the outer ball bearing 4 before deformation;

d is the diameter of the balls 5. At the same time, the ratio of the values of R, R and d must satisfy the condition

5j. ± d f) OS about q TJ); 7J ... and, y /,

R,

a recommended

the number of balls (when used by the Research Institute of Standard Ball Bearings of the Ultralight Series) placed in each of the outer rings of the ball bearing 4 is 9-16 pieces and is determined by the formula

15

P

2 rr (R -) t

0

five

0

five

0

five

where n is the number of balls in each outer ring of the ball bearing nick 4;

t is the positioning ball of the balls 5 in the separator 6 (specified constructively).

The limiting values of the angle about are determined by calculation from the dependences,. 80

t 360 °

  о7 5-jloT and - it was stated / iKKj -d //;

depends on the number of balls 5 in the ring 4.

When assembling, the installation screws are screwed in the direction of the axis of the screw 2 until the first ball 5 contacts the screw groove 3. After that, the screws 8 are displaced by an amount A, until all the balls 5 that are in the angle sector are about will contact simultaneously with the screw groove 3 and with the running point of the outer ring of the ball bearing 4. This contact is determined by a sharp increase in the moment of resistance to twisting on the screws 8, for example, using a torque wrench, after moving each pair of screws 8 by y D angle oi coverage balls 5 screw 2 corresponds to the calculated.

Sha rikopodshipnikovy screw mechanism works as follows.

When the screw 2 is rotated from the drive (not shown), the balls 5 are wrapped around the treadmill of the outer ring of the ball bearing 4 and within the angle et along the helical groove 3, which causes the forward movement of the housing 1 along the axis of the screw 2. The axial rigidity of the mechanism is ensured by the elastic deformation of the outer ball bearing rings 4 when tightened with screws 8.

Claims (1)

Claims of the ball-bearing screw mechanism, comprising a housing, a spindle accommodated therein, ball bearings eccentric to a screw, mounted in the housing at an angle to the screw axis, - equal to the elevation angle of the screw groove, and accommodated in the threaded holes of the housing according to the number of ball bearings screws designed for the connection of ball bearings with screw thread, characterized in that, in order to improve the accuracy and load capacity of the ball bearings are placed in the screw Anavka screws, in the housing, respectively, are the number of ball bearings made of additional threaded holes, the axes of which are inclined, to the axes of the main holes at a central angle of 46-157, and the mechanism is equipped with additional set screws placed in additional threaded holes. 2 Fig.Z