RU2272199C1 - Device for converting rotation into reciprocation - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: device comprises screw, sectional housing with the ring grooves on the inner cylindrical surface, rollers provided with threaded sections and ring grooves that are in coincidence with the ring grooves provided in the housing along the axis of the screw, and balls which are mounted both in the ring groove of the housing and ring grooves of the adjacent rollers. The turns of the threaded sections of the rollers engage the turns of the screw thread, which causes the rollers to move. The balls, which represent separators for the rollers and convert the rotation of the screw into the reciprocation of the housing, transmit the axial load from the rollers to the housing without sliding friction.

EFFECT: enhanced efficiency and durability.

1 cl, 7 dwg

Description

The invention relates to mechanical engineering and can be used as a mechanical screw drive for converting rotational motion into translational.

Known planetary roller screw transmission, see Reshetov D.N. "Machine Details", a textbook for students of engineering and mechanical specialties of universities, 4th edition, Moscow, Mechanical Engineering, 1989, p. 314, consisting of a screw, a nut, and threaded rollers installed between them. The rollers with their end necks are installed in the separators. To exclude spontaneous unscrewing of the rollers, they are additionally connected along the ends with a nut by gears. The turns of the rollers are in threaded engagement with the turns of the screw and nut. At the same time, an internal multi-thread is performed on the nut.

The main disadvantage of this planetary roller screw transmission is the complexity of the design and manufacturing technology, namely, that:

- on the inner surface of the nut, hardened to high hardness, it is necessary to perform high-precision multi-thread (usually five-thread);

- the rollers, in addition to threaded gears with a screw and a nut, are installed in the separators and are connected by gearing to the nut or its housing.

Of the known technical solutions, the closest in technical essence to the claimed device is a device for converting rotational motion to translational, see US Patent No. 4926708 "Apparatus for converting rotary motion into axial motion" Int. Cl. ⁵ F 16 H 25/22, which is selected as a prototype. This device consists of a screw, a housing that performs translational motion, and rollers. At least two annular grooves are made on the inner cylindrical surface of the housing, which has the same axis as the screw. On each roller, annular grooves are made alternating with portions on which a cylindrical thread is cut. The threaded sections of each roller located between adjacent grooves, along one generatrix mesh with the screw thread, and along the opposite generatrix are placed in the annular grooves of the housing. Thus, the number of housing grooves is equal to the number of threaded sections on each roller, and the number of ring grooves made on each roller is one less. The body of the device does not have internal multi-thread, and the device as a whole - separators and gears. When the device is operating, the screw rotates, the rollers make a planetary motion, and the body moves progressively along the axis of the screw. The working axial force is transmitted from the screw to the rollers due to the engagement of the threads of these parts, and from the rollers to the housing due to the contact of the mating surfaces of the rollers with the grooves of the housing with sliding friction. This is a disadvantage of this device, as it leads to a decrease in efficiency and wear of the mating surfaces of the roller and the housing, reducing the durability of the device.

The objective of the invention is to increase the efficiency and durability of the device for converting rotational motion into translational motion, by replacing sliding friction with rolling friction at the interface between the surfaces of the rollers and the housing.

The task is achieved in that the device is equipped with balls, and the number of grooves made on the inner cylindrical surface of the housing is equal to the number of grooves made on the outer cylindrical surface of each roller, and each annular groove on the inner cylindrical surface of the housing is located in one plane perpendicular to the axis screws with corresponding annular grooves made on the outer cylindrical surface of each roller, with each ball located simultaneously in tsevom groove formed on an inner cylindrical surface of the housing, and annular grooves formed on the outer cylindrical surface of the two adjacent rollers. In order for the device to have a constant transfer function, external gear rims are made at the end sections of each roller, which mesh with gear rims made on the inner cylindrical surface of the housing.

The invention is illustrated by the accompanying drawings, where

- figure 1 shows a General view of the device;

- figure 2 shows a section aa in figure 1;

- figure 3 shows an axial section B - B in figure 1;

- figure 4 shows a section bb in figure 3;

- figure 5 shows a section GG in figure 4;

- figure 6 shows an axial section bB of the precast housing having four annular grooves;

- Fig.7 shows an axial section bB of the device with additional gears between the rollers and the housing covers.

A device for converting rotational motion into translational movement, see FIGS. 1 and 2, consists of a screw 1 and a node performing translational movement. The prefabricated housing of this assembly consists of a base part 2 and two covers 3, which are connected to the base part by screws 4 with spring washers 5. Other housing designs are possible that provide assembly and operation of the device.

Two covers 3 and the base part 2, see figure 3, form on the inner cylindrical surface of the housing, which has the same axis as the screw, two annular grooves "D". On each roller 6, the same number of annular grooves "E" are made as on the inner cylindrical surface of the housing, and threaded sections "Zh" that alternate with grooves "E". Moreover, each annular groove "D" on the inner cylindrical surface of the housing is located in one plane perpendicular to the axis of the screw, with the corresponding annular groove "E" of each roller 6. The turns of the threaded sections "G" of each roller are engaged with the threads of the screw 1. To retain the lubricant inside the housing, oil scraper rings 7 are installed in the covers 3.

In each annular groove "D" of the housing between adjacent rollers 6, balls 8 are installed, see Figs. 3-5. Moreover, each ball 8 is also installed in the annular grooves "E" of two adjacent rollers. In order to have the smallest possible gaps between the ball and the three mentioned grooves, in which the ball is simultaneously located, a geometric calculation is necessary.

On the inner cylindrical surface of the precast housing, the number of grooves "D" can be more than two, as well as the number of corresponding grooves "G" on the rollers. For this, at least one additional part 9 is introduced into the device. Fig. 6 shows an axial section of a prefabricated housing having two additional parts 9. Moreover, the number of grooves "D" on the inner cylindrical surface of the housing, and therefore the grooves " F "on rollers, equal to four.

The device described above, due to slipping at the interface between the screw and the rollers, rollers and balls, balls and the housing, may have an unstable axial movement of the housing with the rollers and balls during uniform rotation of the screw (variable transfer function). Devices for converting rotational motion into translational motion with a variable transfer function can be used, for example, in locking mechanisms, jacks, and so on.

In order for the proposed device to have a constant transfer function, additional communication between the rollers and the housing, for example, gears, is necessary. In this case, see Fig. 7, at the ends of each roller 6, external gear rims "I" are made, and in the hole of each cover 3, internal gear rims "K" are made. Internal gear crowns can be cut into special bushings that are fixed in the holes of the covers when assembling the device.

A device for converting rotational motion into translational works as follows. The screw 1, see Fig.3-5, rotating, drives the rollers 6, which make a planetary motion. The rollers are fixed from axial displacement relative to the housing due to balls installed in the annular grooves of the housing and the rollers. This is the mechanism for converting the rotational motion of the screw into the translational motion of the housing together with all the parts installed in it. In this case, the balls 8 will roll along the annular grooves "D" of the housing and perform additional spinning under the action of friction forces, similarly to the balls of ball angular contact bearings. In addition, balls are separators for rollers.

In the prototype device, the working axial force is transmitted from the rollers to the housing due to the contact of the surfaces of these parts with sliding friction. In the inventive device due to the introduction between the rollers and the housing of additional parts - balls, friction sliding is replaced by rolling friction, which helps to increase the efficiency device, reduces wear on contact surfaces and increases durability. In addition, the starting torque is reduced on the screw.

Claims (2)

1. A device for converting rotational motion into translational, containing a screw, a housing, on the inner cylindrical surface of which, coaxial with the screw, at least two annular grooves are made and rollers installed between the screw and the housing having alternating annular grooves and threaded on the outer cylindrical surface sections that engage with the screw thread, characterized in that the device is provided with balls, and the number of grooves made on the inner cylindrical surface of the housing is equal to the number the grooves made on the outer cylindrical surface of each roller, and each annular groove on the inner cylindrical surface of the housing is located in the same plane perpendicular to the axis of the screw with the corresponding annular grooves made on the outer cylindrical surface of each roller, with each ball located simultaneously in the annular a groove made on the inner cylindrical surface of the housing, and in annular grooves made on the outer cylindrical surface of two adjacent rollers ikov. 2. The device according to claim 1, characterized in that at the end sections of each roller there are external gear rims that mesh with gear rims made on the inner cylindrical surface of the housing.

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