SU709318A1 - Machine tool working member power drive mechanism - Google Patents

Description

I

The invention relates to the field of machine tools and can be used to force the movement of the working body of the machine.

A mechanism for powering the working body of a machine tool is known, comprising a follower and a driving element in the form of a rail and a screw, a rotational drive and a reciprocating movement of the screw, ending with an eccentric acting on the shaft of the screw.

A disadvantage of the known mechanisms is the presence of friction sliding in a pair of worm to-rail, which leads to its wear. 1.

in order to increase the accuracy and smoothness of movement by eliminating sliding friction in the engagement of the worm-to-rake pair, the torque of the rotational drive motor is selected with a torque limit equal to the friction moment in the worm-to-rake pair, and the eccentric is designed with an eccentricity corresponding to the maximum axial the gap in the engagement of the H-rake pair.

FIG. 1 shows the kinematic scheme of the mechanism; in fig. 2 - engagement of the screw with the rail of the mobile unit.

The mechanism contains the leading element -

screw to 1 mounted on shaft 2 rotatably independently

and fixed against axial displacement.

Worm to 1 is equipped with a rotation drive 3,

driven by an electric motor 4

DC and low power and you

sub-frequency drive 5 reciprocating movement, which has

eccentric shaft 6 with eccentricity e.

Worm to 1 mounted in a fixed node 7 and coupled with the rail 8, mounted on the movable node 9.

FIG. Figure 2 shows the gap between the turns of the screw and the slats equal to 2e.

The mechanism works as follows.

The high-frequency drive motor 5 is engaged in reciprocating movement, which rotates the eccentric shaft 6. The eccentric shaft 6 acts on the screw of the worm 1, together with it the high-frequency reciprocating

moving by 2e, equal to two eccentricities of shaft 6. When the shaft 6 is rotated 1/2 turn, the eccentric draws the worm to 1 from the rail 8 by 2e. Simultaneously with the retraction drive, the rotation drive 3 turns the screw to 1 by an angle corresponding to the selected speed of movement of the rail 8 (or the machine tool) and proportional to the axial movement of the screw coil equal to 2e.

When the shaft b is rotated to the next 1/2 turn, the eccentric of the shaft b moves the rail 8 through the screw to 1 also by the value 2e.

The rotation drive 3 continuously rotates the worm to I From the moment the worm 1 is retracted from rail 8 to its next approach to it. The rotation of the screw 1 continues until contact between the turns of the screw 1 and the teeth of the lath 8. With this contact, there is a moment of friction, which is greater than the twist torque of the rotation drive 3. The rotation of the screw 1 stops.

The movement of the rail 8 comes from the pressure of the turns of the screw 1 on the teeth of the rail 8 in the direction of movement of the machine tool.

The rotation of the screw 1 takes place during the entire time of its movement back, i.e. in the direction opposite to that of the working body 9 of the machine.

With such a rotation of the screw 1, there is no friction in its engagement with the rail 8. The angle, and which will have time to turn the screw to 1, will give the amount of movement of the contact point of the turn of the screw 1 along the center line. This value should be smaller or equal to the gap between the turns of the screw 1 and the teeth of the rack 8 to exclude friction between them.

When the screw 1 is axially moved forward by 2e, i.e., in the direction of movement of the working element 9, the teeth of the rail 8 are pressed with a force equal to the pull force. In this case, the contact force in the engagement instantly gives rise to a great friction force, which stops the rotation of the screw 1.

The motor 4 of the rotational drive 3 is of low power, unable to turn the transmission chain and is braked while remaining under voltage. Work cycle

rotation drive 3 is repeated every time the worm goes backwards.

The speed of movement of the working body 9 depends on the speed of rotation of the actuator 5 and the speed of reciprocating movement. The direction of movement of the working opra.ia 9 depends on the direction of rotation of the actuator 3.

Thus, the worm to 1 performs a high-frequency oscillatory motion in the axial direction by an amount of 2e, equal to the gap between the turns of the screw 1 and the teeth of the lath 8, which creates the effect of their backlash-free engagement:

Combination of work of rotational drives 3

and drive 5 high-frequency reciprocating movement provides

smooth movement of the working body 9,

eliminates friction in the engagement of the screw 1

with rail 8, which allows you to speed up

rotation of the screw 1, and, therefore, the movement of the working body 9 of the machine.

The low power of the electric motor 4 of the rotational drive 3 allows for the performance of the reverse and precise stopping of the movable working element 9 necessary for the automation of machine tools.

Claims (1)

Invention Formula The mechanism of force movement of the working body of the machine, containing the driven and driving elements in the form of a rod and a screw, drives the rotation of the screw and drives the reciprocating movement of the screw, the last chain link of which is an eccentric acting on the shaft of the screw, characterized in that , in order to improve the accuracy and smoothness of shifting by eliminating friction in engagement of the screw and rail, the torque of the rotational drive motor is selected with a torque limit equal to the moment of rubbing in the pair of the screw to the rail, and the eccentric is made with an eccentricity corresponding to the maximum axial clearance in the engagement of the H-rake pair. Sources of information taken into account during the examination 1. Kozhevnikov, S. N. and others. Mechanism. Anchors, 1965, p. 623, fig. 8.69. 18