Abstract:
The invention relates to a compact linear roller guide which makes it possible to transmit high forces and torques between a carriage ( 1 ) and a guide rail ( 3 ). The carriage ( 1 ) comprises two or more pairs of ribbed rollers ( 2 ), rotatably supported on the side walls of the carriage by means of bearings, between which the rail ( 3 ) is inserted, with a complementary cross-section, The simultaneous contact of the planar and convex surfaces of the rail ( 3 ) with the cylindrical and concave surfaces of the rollers ( 2 ) enables uniform distribution of the loads on said bearings and a compact configuration of the guide.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Linear roller guides have been extensively studied and developed in recent years with the objective of increasing the precision of the linear movement, the axial and radial load capacity, the rigidity and the working life of said guides through the utilization of stronger and more hardwearing materials, the development of more efficient manufacturing techniques and the minimization of the size thereof with the objective of the implementation thereof in applications requiring both precision and high load capacity. 
         [0002]    At the present time, for precision applications, there exist three types of linear guide systems, viz: (1) systems of shafts and linear ball bearings: for applications requiring a precision not greater than tens of microns, typically of the order of hundreds of microns; (2) guides with slides on rails: for applications having a precision of up to tens of microns or less and (3) precision guides for applications having a precision of units of microns. 
         [0003]    However, when a linear guide system refers to precision it does not refer to high load capacity or vice versa, by virtue whereof it is necessary to satisfy both demands in the new applications for linear guides which require both characteristics to be offered. 
         [0004]    Different configurations of linear guides have been described in the state of the art, for example the document DE 4324059 discloses a linear guide comprising a guide carriage system, a guide rail or track and rolling elements formed by a system of low-friction ball bearings. This linear guide comprises at least four rolling elements which, in this case, are ball bearings embedded in a system which holds them which, in turn, is attached to the guide carriage. These rolling elements are located in such a manner as to form geometrically equidistantly located reciprocally-parallel planes. The configuration of the rail may be appreciated in said document, it being grooved to receive the rolling elements, or it may present a convex surface which is embedded in said rolling elements. 
         [0005]    It has also become necessary to enhance the components comprising the guide with the objective of increasing the precision of the linear displacement, of increasing the load capacity and the rigidity of the guide, and of conferring additional qualities, such as the capacity to accept axial and radial loads. In this manner the document US 2003070465 discloses a track for linear guides including one or more raceway tracks or slots whereupon the rolling elements are supported and which are displaced along said track. Said track for linear guides presents the characteristic of being grooved, allowing the rolling elements to be located in a fixed manner in the slot of the rail, permitting said elements to be displaced with less friction by virtue of the low roughness of the surface. The foregoing discloses different configurations for the rail which permits the quantity of rolling elements to be varied and achieve different ways of locating them according to the requirement of the application. Similarly, it discloses different manufacturing procedures of said rail with the object of eliminating the disadvantages presented by the conventional rails of the linear guides and reducing the manufacturing cost, maintaining the exactitude and precision of said devices. 
         [0006]    The present document discloses a compact linear roller guide which, by virtue of the configuration and geometric distribution thereof, is capable of transmitting forces and high tension moments, in addition to achieving high precision in the linear displacement of the load. This linear guide in turn presents novel characteristics, such as the implementation of grooved rollers guided by means of a guide rail having surfaces especially designed to uniformly distribute the load on all the rollers comprised in the sliding carriage. The constructive characteristics of the present linear guide permit a system of power transmission to be realized between the sliding carriage and the guide rail by inserting a motor and the support thereof into at least one of the walls of the sliding carriage and within the space between the grooved rollers in such manner that, by means of a pinion mounted on the motor shaft, power may be transmitted to the rail by a longitudinally abutting rack, maintaining the very small physical dimensions, permitting the utilization of said linear guide in diverse applications requiring both precision and high load capacity. 
     
    
     
       DESCRIPTION OF THE FIGURES 
         [0007]      FIG. 1  provides a perspective illustration of an embodiment of the linear roller guide according to the present invention. 
           [0008]      FIG. 2  is a view of a transverse plane of the guide depicted in  FIG. 1 , wherein there is depicted how the guide and load transmission rail is inserted within the assembly of a pair of rotational support elements and grooved rollers and, furthermore, how the latter are mounted in the lateral walls of the sliding carriage. 
           [0009]      FIG. 3  is a cross sectional perspective view of the guide depicted in  FIG. 1 , wherein the upper and lower plates of the guide carriage have been omitted to depict the disposition of two pairs of rotational support elements and grooved rollers, and how the guide and load transmission rail is longitudinally inserted therebetween. 
           [0010]      FIG. 4  is a perspective view of the guide depicted in  FIG. 1 , wherein the components of the sliding carriage are depicted in detail. 
           [0011]      FIG. 5  depicts the novel system of power transmission employed by the linear guide of the invention, which is connected between the sliding carriage and the guide and load transmission rail. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0012]    The present invention discloses a compact linear roller guide capable of transmitting forces and high torques between a sliding carriage, defined by a longitudinal axis and a rectangular cross section, and a guide and load transmission rail inserted longitudinally into the carriage and housed between an assembly of rotational support members and grooved rollers mounted in the sliding carriage, said grooved rollers radially traversing the sliding carriage, to be inserted in a perpendicular manner into two of the facing lateral walls thereof, said insertion being realized in the internal raceways of respective bearings mounted in said facing lateral walls, the rollers being disposed in at least two pairs distributed in both radial planes separated by a certain distance above the longitudinal axis. The planar and convex bearing surfaces of the guide and load transmission rail are in simultaneous contact with the corresponding planar and concave bearing surfaces of all the grooved rollers of the at least two pairs of rollers. Said simultaneous contact permits the uniform distribution of forces and torques between the rotational support bearings, reducing the load demands on said individual bearings. Such constructional characteristics permit the linear guide of the present invention to maintain physical dimensions considerably smaller than the existing art whilst supporting the same load demands. 
         [0013]    In another aspect of the present invention there is disclosed a compact linear roller guide capable of transmitting forces and high torques between a sliding carriage, defined by a longitudinal axis and a rectangular cross section, and a guide and load transmission rail inserted longitudinally into the carriage, housed between an assembly of rotational support members and grooved rollers mounted in the sliding carriage, wherein the bearings whereby the grooved rollers are supported receive axial and radial loads, but wherein the transmission of the load between the sliding carriage and the guide and transmission rail is uniformly distributed between the individual bearings in such a manner that a special design of the latter is not required, consequently standard bearings may be employed facilitating the construction of the linear guide. 
         [0014]    In a third aspect of the invention there is disclosed a compact linear roller guide capable of transmitting forces and high torques between a sliding carriage, defined by a longitudinal axis and a rectangular cross section, and a guide and load transmission rail inserted longitudinally into the carriage and housed between an assembly of rotational support members and grooved rollers mounted in the sliding carriage, wherein the constructional characteristics of the present invention permit the realization of a system of power transmission between the sliding carriage and the guide and load transmission rail, maintaining small physical dimensions when a motor and the support thereof is inserted in at least one of the walls of the sliding carriage in the space between the pairs of grooved rollers such that, by means of a pinion mounted on the motor shaft, power may be transmitted to the guide and load transmission rail by a rack abutting onto the corresponding longitudinal flank. 
       DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION 
       [0015]      FIG. 1  provides a perspective view of an embodiment of the linear guide of the present invention wherein there is included a sliding carriage  1 , having a plurality of rotational support and rolling elements  2 , and a guide and load transmission rail  3 . The guide and transmission rail  3  is inserted within the sliding carcass supported by the rotational and rolling support elements  2 . 
         [0016]      FIG. 2  depicts a cross section of the linear guide without the upper and lower portions of the sliding carriage  1 , showing in detail the insertion of the guide and load transmission rail  3  which extends longitudinally from each of the extremities, consequently defining an axial axis  4 , depicted in  FIG. 3 , being radially intersected by two axes, a major radial axis  5  which in turn intersects a minor radial axis  6 . The axial axis  4  and the radial axes  5  and  6  are orthogonal, reciprocally intersecting in the center of the cross section  7  of the guide rail  3 . The cross section  7  is formed principally by a central rectangular region whereof the greater sides run parallel to the major radial axis  5  and the smaller sides run parallel to the minor radial axis  6 . Commencing from this rectangular region, and centered on the minor radial axis, from each greater side there projects a convex area  8 . In  FIG. 3  it may be observed how the longitudinal extension of the cross section  7  produces planar longitudinal rolling surfaces  9  and convex rolling surfaces  10  and two longitudinal flanks  11 , these latter may be used to attach any power transmission system for the linear guide. The adjacent areas between the planar longitudinal rolling surfaces  9  and convex rolling surfaces  10  serve to prevent the lateral displacement of the guide and load transmission rail  3  and to transmit radial loads between this latter and the grooved rollers  21 . The combination of a central rectangular section and a convex section adjacent to each greater side of the rectangular section, and projected longitudinally as described, confer on the guide and load transmission rail  3  the capacity to transmit and support high torsion loads. 
         [0017]      FIG. 4  depicts the sliding carriage  1  comprising a first plate  12  facing and parallel to a second plate  13 . A third plate  14  joins the first plate  12  and the second plate  13  along one of the coincident longitudinal edges thereof, a fourth plate  15  joins the first plate  12  to the second plate  13  along the coincident longitudinal second edges thereof. Plates  12 ,  13 ,  14  and  15  define a longitudinal axis and a rectangular cross section for the sliding carriage  1  such as to confer thereon a structure capable of transmitting high torsion loads. In plate  12  there are at least four through-orifices  17 , each of said orifices being faced by a corresponding orifice in the second plate  13 , the central axis of each pair of facing orifices being aligned with a coincident axis  18  perpendicular to the first plate  12  and to the second plate  13 , forming a pair of facing and aligned orifices  19 . Such an arrangement creates at least four axes of alignment  18  between the facing orifices of plates  12  and  13  and perpendicular to the latter. These orifices serve for the mounting of the plurality of rotational support and rolling elements  2 .  FIG. 4  depicts the configuration of the plurality of rotational support and rolling elements  2 ; in each of the orifices forming the pair of facing and aligned orifices  19  there is mounted a bearing for combined axial and radial loads  20 . Each of the at least four pairs of facing and aligned orifices  19  and the respective bearings thereof for combined axial and radial loads  20  serve as support for one of the at least four grooved rollers  21 , each roller being supported at its end shanks  22  by the bearings for combined loads  20 . The grooved rollers  21  have a step  23  at the extremities thereof created by the reduction in the diameter thereof to form the end shanks  22  which are inserted into the bearings for combined loads  20 , the shoulder formed by said step serving as a surface of transmission of axial loads on the grooved rollers  21  towards the bearings for combined loads  20 . With such a distribution each alignment axis  18  coincides with the corresponding geometric axis of one of the at least four grooved rollers  21 , also coinciding with the central axes of the bearings for combined loads  20  and with the corresponding pair of facing and aligned orifices  19 . In this manner there are at least four support and rolling complexes  24 , viz: grooved roller  21  supported on each end shank  22  by a bearing for combined loads  20 , in turn mounted in a pair of facing and aligned orifices  19 , each thereof having an alignment axis  18 . In turn, these at least four support and rolling complexes  24  are distributed in two pairs, wherein a first pair is organized in a first plane  25  coincident with a cross section of the sliding carriage  1  in such a manner that the corresponding alignment axes  18  of each support and rolling complex  24  run parallel within said coincident plane  25 , separated by a certain radial distance c. A second pair of support and rolling complexes  24  is organized in a second plane  27  coincident with a cross section of the sliding carriage  1 , and located at a certain distance d on the longitudinal axis  4  perpendicular to planes  25  and  26 , in such manner that the corresponding alignment axes  18  of each support and rolling complex  24  run parallel within said coincident plane  27  separated by a certain radial distance c. 
         [0018]    The guide and load transmission rail  3  is inserted longitudinally into the sliding carriage  1  within the intermediate space which is formed by virtue of the axial separation c between the alignment axes  18  of the respective support and rolling complexes  24  located in the corresponding transverse planes  25  and  26 . In  FIG. 2  it is depicted how the guide and load transmission rail  3  is in simultaneous contact with all the grooved rollers  21  of the at least two pairs of rollers, the line of contact between each grooved roller  21  and the planar longitudinal rolling surfaces  9  and convex rolling surfaces  8  of the guide and load transmission rail  3  is adjusted such that there is no play in movement other than the linear movement in the longitudinal direction. The transmission of radial loads in the direction of the minor radial axis  6  of the guide and load transmission rail  3  is realized by means of the contact between the linear region of the grooved rollers  21  and the planar longitudinal rolling surfaces  9  of the guide and load transmission rail  3 . The transmission of radial loads in the direction of the major radial axis  5  of the guide and load transmission rail  3  is realized by means of the contact between the concave region of the grooved rollers  21  and the convex rolling surfaces  10  of the guide and load transmission rail  3 . In the foregoing manner linear guiding and load transmission is achieved free of play between the sliding carriage  1  and the guide and load transmission rail  3 . 
         [0019]      FIG. 5  depicts an additional aspect of the linear guide according to the present invention. In this embodiment, provision is made for a system of power transmission for the linear guide connected between the sliding carriage  1  and the guide and load transmission rail  3 . The system of power transmission includes at least: the orifice for mounting the motor  28 , a motor  29 , a motor support  30 , a pinion  31  and a rack  32 . The motor is mounted directly on one of the plates of the sliding carriage  1 , for the purposes of illustration in this case on the first plate  12 , by means of the insertion aperture  28  located between two pairs of the support and rolling complexes  24 , the orifice  28  permitting the insertion of part of the motor  29  together with the support  30  thereof. For a compact design the pinion  31  may be mounted directly on the motor shaft  29  in such a manner that the connection is realized directly upon the rack  32  which is mounted on one of the lateral flanks  11  of the guide and load transmission rail  3 .