MX2010011861A - Anti backlash monolithic flexible nut. - Google Patents

Abstract

The anti backlash monolithic flexible nut describes a monolithic mechanical element, i.e., made of a single piece, which has two sections: a support section that includes a first and a second element transversally located with regard to the power screw; a flexible section, which comprises at least two flexion beams and which may be located at any point in the first and second element, since they act as joint beams between said elements allowing the inventive nut to be compressed or expanded in the direction of the power screw axis, thereby compensating and mitigating the backlashing effects that may occur between the screw thread and the flexible nut thread. The support section has a threaded central orifice passing through the first and second element through which a power screw is introduced; the screw, along with the flexion beams, turns the rotating motion of the power screw into a linear movement of the flexible nut, which is simultaneously fastened to any element that requires a ccurate movements.

Description

Anti monolithic flexible nut FIELD OF THE INVENTION The present invention relates to mechanical devices that make the operation of machines more efficient; such is the case of threaded mechanical elements or with friction surfaces to transmit a movement, as are the power screws; specifically, particular devices that serve to compensate the gap between the threads of a screw and a nut, in such a way that the effect of the play between both is reduced or even eliminated.

OBJECT OF THE INVENTION The present invention mentions a mechanical element of precision of transmission of movement, in particular to a flexible monolithic anti-game nut capable of converting rotary movement to linear movement through friction and at the same time eliminating the play (backlash) between a screw and a nut, which is necessary when very precise movements are required, as in the movement of the axis of a machine tool, either conventional or numerical control.

BACKGROUND Numerous devices have been invented to eliminate the play between the screw and the nut, to provide precision to specific movements such as that of the axes of a machine tool; These devices are usually composed of multiple parts which require assembly for operation, so the size and maintenance cost of the same is increased, as well as the potential for error when having more elements assembled. The mechanism of the flexible monolithic anti-game nut, replaces the inventions that are mentioned below as it is a one-piece element, unlike the existing ones, which are formed of several pieces, in addition to the structure of the element presented here allows to predetermine the amount of deformation / compression of the flexible part of the nut. This in turn allows pre-determination of the preload and the torque required to turn the nut. The geometrical design of the monolithic flexible anti-game nut, coupled with the adequate selection of the material, and considering its mechanical properties allows to establish the magnitude of the compression of the flexible part of the monolithic element.

In the state of the art, there is the ball screw (ballscrew), which is one of the main methods of coupling between the screw and motor, for the conversion of the rotary movement of an electric motor to the linear displacement of structural components of machines. The ball screws use a screw with a nut containing posts or balls to reduce friction. Its operation is similar to that of a rolling element bearing, which contains small metallic spheres that rotate through a channel as the screw advances. This device differs from the proposed invention, since the ball screw has several pieces joined in such a way that the device operates efficiently, while the monolithic flexible anti-play nut is one piece.

The document entitled "Antibacklash spring mounted nut", with patent number US4434677, mentions a nut which consists of a body with grooves, which compensate the play between screw and nut, when coupled and pressed with a ring to the end of the nut. the nut. This element consists of several pieces and is more bulky than the monolithic flexible anti-game nut proposed here. The patent US4954032 mentions a reinforced nut, composed of several parts, in which a spring acts by pressing one of the longitudinal faces of one of the two parts of the nut against teeth that are in one of the elements, thus exerting the pressure against a screw that is inserted through the mediation of this nut. Like the previous patent, this element consists of several parts, including a spring, causing it to be more bulky and more complex than the monolithic flexible anti-game nut. In the same way the document "Reinforced anti backlash nut" with patent number US5027671, mentions a nut of several pieces, among them a spring; This nut also has grooves which function as bending means and are located longitudinally and tangentially to the movement of the nut, differing totally with the element proposed by requiring multiple components to perform its function of eliminating the game.

A nut comprised by two holes, a central screw and springs, which are pressed axially to compensate the backlash between the screw and the nut aided by the tightening of an external thread, is what is described in the document US5303606, and that solves the same problem as the mechanism of the flexible monolithic anti-game nut, but the latter with a single piece.

Document US6041671, proposes an anti-play nut mechanism, which is composed of a pair of nuts, which are threaded and joined by a washer, so there is a free space, which is occupied by a central screw that performs the compensation of the game. This mechanism differs from the proposed one since it has an assembly of several pieces unlike the flexible monolithic anti-game nut that is only one piece. Also, a nut that moves through a main screw, towards two longitudinal directions, is described in patent US5913940; this document mentions that the nut has threaded sections, as well as a kind of notches, which allow the precision in the movement of the screw; This device differs from the proposed one, since the monolithic flexible anti-game nut has no notches, besides it is a one-piece device. Finally, the patent entitled "Backlash free adjusting mechanism" and number US4279173, explains the operation of a device composed of several helical wires that has movement thanks to a mobile support, arranged concentrically and separated by a spring; again this device differs from the proposed one since it is a multi-piece mechanism, while the monolithic anti-game flexible nut consists of only one piece.

BRIEF DESCRIPTION OF THE FIGURES Figure 1. Isometric view of the monolithic flexible anti-game nut.

Figure 2. Transparent isometric view of the monolithic anti-play flexible nut. Figure 3. Front view of the monolithic flexible anti-game nut.

Figure 4. Front view of the flexible monolithic anti-gaming type tie beam beam.

Figure 5. Front view of the flexible monolithic anti-gullet type girder beam.

DETAILED DESCRIPTION OF THE INVENTION The monolithic flexible anti-play nut is a monolithic mechanical element, that is, a single piece, made of metal, plastic or other material that preferably has linear elastic behavior, to facilitate the design and modeling of the response of behavior of the same, but that is not limited to linear elastic materials, because materials that improve performance can be used selectively, for example, coatings to reduce wear or non-linear materials that have a variable performance for any application that requires it . In this flexible monolithic anti-game nut, two functional structural sections are distinguished: a supporting section and a flexural section. In Figure 1, one of the two structural sections is observed, the support section, which is made up of two elements: a first element (1) with circular, oval or polygonal geometry, preferably rectangular positioned transversely to the displacement of a nut with respect to the length of a power screw (5); and a second element (2) of circular, oval or polygonal geometry, preferably rectangular, also placed transversely to the displacement of the nut and parallel to the first element (1), so that they are aligned with each other, and where the dimensions of the first element (1), of the second element (2) or both, allows having a threaded central hole through which passes a power screw (5), as well as at least a pair of through holes (7 and 8) that may or may not be threaded; These through holes (7 and 8) are located, either in the first element (1), or in the second element (2), located at any point within the area of the first element (1) or the second element (2). ), to facilitate the clamping of the monolithic flexible anti-play nut with the element that is to move the rotary movement to linear, which can be a displacer carriage, a work table, or an adapter to facilitate the assembly of other equipment (6) The dimensions of the first element (1) and the second element (2) are preferably the same; for the correct functioning of the monolithic flexible anti-play nut only the first element (1) or the second element (2) must be attached to the trolley, work table or adapter (6). Once the first element (1) or the second element (2) is fixed to the car or to the element in which the precision is required, the element that has not been fastened is free to move with respect to the one that is subject to the car. or table.

The bending section comprises at least two flexible elements, called bending beams (3 and 4), which preferably have the same mirror geometry and which can be placed at any point of the first element (1) and the second element ( 2), since they serve as connecting beams between the first element (1) and the second element (2); in normal operation, the bending beams (3 and 4) are compressed or expanded in the same direction as the axis of the power screw (5). The geometry of the bending beams (3 and 4) is defined considering the movement required between the first element (1) and the second element (2), and can be made more rigid or more sensitive, as the case may be. The design of the geometry of the bending beams (3 and 4) can be done previously for specific applications; for example, the geometry can be in the form of "U" (see figure 4) or semicircular (see figure 5). With the geometry in the beams of flexure (3 and 4) in the form of "U" (see figure 4), the monolithic flexible nut anti-game becomes more rigid, characteristic necessary in some industrial application; on the other hand, the semicircular geometries (see figure 5) for the bending beams (3 and 4), are more sensitive to the applied forces, characteristic necessary, for example, in optical applications. The design of the beams of flexion (3 and 4) is not limited only to the two geometries described here (figures 4 and 5), since these geometries are designed depending on the stiffness required, where preferably curved geometric shapes are used , since they facilitate the flexion.

The support section, that is, the first element (1) and the second element (2), have in their middle part a threaded central hole that is aligned with the first element (1) and second element (2). During the insertion of the monolithic flexible anti-play nut into the power screw (5), the bending section compresses a distance of at least one step of the power screw (5), thus leaving the first element (1) ) and the second element (2) closer to each other than when they are not mounted on the power screw (5). In case there is a gap or play between the thread of the monolithic flexible nut and the power screw (5), this gap is eliminated, since the flexible beams (3 and 4) allow the expansion of the monolithic flexible nut anti-game, that is, allows controlled separation between the first element (1) and second element (2). The play between the cord of the power screw (5) and the thread of the threaded center hole is reduced or eliminated completely by the pressure exerted by the bending beams (3 and 4) on the teeth of the first and second element threading ( 1 and 2), thus allowing to perform high precision linear movements.

Claims (11)

CLAIMS Having sufficiently described my invention, I consider it a novelty and therefore claim as my exclusive property, what is contained in the following clauses:

1. A flexible monolithic anti-game nut characterized in that it comprises a monolithic mechanical element in one piece, where 2 sections are distinguished; a support section, and a flexure section, wherein the support section is formed by a first element and a second element parallel to each other, and where the flexure section is formed by at least two bending beams of the same geometry in image mirror which serve as a union between the first element and the second element.

2. The monolithic flexible anti-game nut according to claim 1, characterized in that the monolithic mechanical element can be of any material exhibiting linear elastic behavior, preferably metal or plastic.

3. The monolithic flexible anti-game nut according to claim 1, characterized in that the first element and the second element have a circular, oval, polygonal or combination of the above and preferably both rectangular geometries.

The monolithic flexible anti-game nut according to claim 1, characterized in that the first element and the second element have at least one pair of through holes that may or may not be threaded therein and that allow the fastening of a carriage, table work or adapter.

The monolithic flexible anti-game nut according to claim 1, characterized in that the dimensions of the first element and the second element are preferably the same.

The monolithic flexible anti-game nut according to claim 1, characterized in that the first element and the second element are transverse to the length of the power screw and joined together by at least two bending beams.

The monolithic flexible anti-game nut according to claim 1, characterized in that the bending beams preferably have the same mirror geometry.

8. The monolithic flexible anti-game nut according to claim 7, characterized in that the bending beams can be placed at any point along the length of the first and second elements, since they serve as connecting beams between these elements.

9. The monolithic flexible anti-game nut according to claim 7, characterized in that the geometry of the bending beams can be designed depending on the stiffness that is preferably required using curves that facilitate bending.

10. The monolithic flexible anti-game nut according to claim 1 characterized in that a threaded central hole is in the middle part of the support section, allowing the first and second elements to be aligned with each other.

11. The monolithic flexible anti-game nut according to claim 10 characterized in that a power screw passes through the threaded central hole.