Abstract:
A guide rail and method of forming a guide rail is provided. The guide rail includes a base rail having a groove with a plurality of fingers formed therein and a race insert mounted in the groove. The race insert has at least two different load directions. The fingers extend generally non-parallel to the different load directions. The fingers are preferably deformed into a state of bending.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This patent application claims the benefit of U.S. Provisional Patent Application No. 61/034,540, filed Mar. 7, 2008, the entire teachings and disclosure of which are incorporated herein by reference thereto. 
    
    
     FIELD OF THE INVENTION 
     This invention generally relates to guide rails and more particularly guide rails including a base rail including at least one raceway insert. 
     BACKGROUND OF THE INVENTION 
     Guide rails are used as a bearing and guide to support and direct the movement of a carriage, also known as a saddle, mounted to the guide rail. In some embodiments, the carriages will include metal rollers or guide wheels that ride on raceways of the guide rail. 
     As technology continues to strive to reduce weight, manufacturing time and manufacturing costs (with an emphasis on material costs) while maintaining structural integrity and tolerancing, numerous guide rail configurations have been developed. 
     One particular configuration is the use of a base rail formed of a lighter weight, cheaper base material such as aluminum to which harder, more wear resistant, and accurate raceways are mounted. 
     For example, U.S. Pat. No. 5,800,065 to Lyon teaches providing an extruded base member including a longitudinal groove on opposite sides of the base member. A carriage race is inserted into each of the grooves. The teachings and disclosure of U.S. Pat. No. 5,800,065 are hereby incorporated in its entirety by reference thereto. 
     U.S. Pat. No. 7,300,208 to Kuellstaedt teaches a similar guide rail that includes support ribs formed in the bottom of the grooves of the base member that are deformed during assembly of the guide rails. U.S. Pat. No. 7,300,208 emphasizes the importance of having the support ribs substantially parallel to the load transmission direction of the race. This configuration allows the support ribs to deform in a mushroom pattern with a portion of the rib deforming to both sides of the rib and permits generally placing the support ribs in a state of compression rather than bending. Further, these ribs extend at an angle relative to the direction in which the race is roller inserted into the grooves of the base member. The teachings and disclosure of U.S. Pat. No. 7,300,208 are hereby incorporated in its entirety by reference thereto. 
     The present invention provides improvements over the guide rails taught by U.S. Pat. No. 5,800,065 and U.S. Pat. No. 7,300,208. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention has several aspects that may be claimed and stand as patentable independently and individually or in combination with other aspects, including but not limited to the following. 
     In one embodiment of the invention, a guide rail includes a base rail and a race insert mounted to the base rail. The base rail includes a mounting groove. A plurality of fingers extend from a bottom of the groove. The race insert has two race ways that have different load transmission directions. Each race way is associated with a corresponding portion of the plurality of fingers. The load direction of the corresponding race way is non-parallel to the corresponding portion of the plurality of fingers. The race insert is mounted against the plurality of fingers. 
     In another embodiment of the invention, a method of forming a guide rail is provided. One step of the method includes forming at least one groove having a plurality of fingers extending from a base of the groove in a base rail. Another step includes mounting a race insert to the base rail with the race insert pressed in contact with the plurality of fingers. The step of mounting the race insert includes bending a first set of the plurality of fingers in a first direction and bending a second set of the plurality of fingers in a second direction, generally opposite the first direction. 
     Other embodiments of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings: 
         FIG. 1  is an exemplary embodiment of a guide rail in accordance with the teachings of the present invention; and 
         FIG. 2  is an end illustration of the base rail of the guide rail of  FIG. 1 ; 
         FIG. 3  is an enlarged partial illustration of the guide rail of  FIG. 1  illustrating the mounting arrangement of the race insert mounted to the base rail. 
     
    
    
     While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a guide rail  100  according to the teachings of the present invention. The guide rail  100  includes a base rail  102  and a pair of race inserts  104 ,  105  mounted to the base rail  102 . The base rail  102  is preferably formed from a lighter and/or softer material than the race inserts  104 ,  105 . Typically, the base rail  102  is an extrusion formed from aluminum and the race inserts  104 ,  105  are a steel or other wear-resistant material. 
     In a preferred embodiment, the race inserts  104 ,  105  form a gothic arch profile including race ways  108 - 111 . As is known in the art, a ball bearing (not shown) carried by the raceways  108 - 111  will only contact the race ways  108 - 111  at a single point when using a gothic arch profile. Further, as is more fully described in U.S. Pat. No. 7,300,208, such a race insert  104 ,  105  includes two load transmission lines that extend at an angle relative to one another. These load transmission lines are illustrated by arrows  112 ,  114 . However, other designs and profiles may be used while remaining within the scope of the present invention. 
     The race inserts  104 ,  105  are mounted in grooves  116 ,  118  formed in opposed sides of the base rail  102 . Typically, tabs  120  are swaged over the ends of the race inserts  104 ,  105  to secure the race inserts  104 ,  105  within the grooves  116 ,  118 . 
     When assembling the guide rail  100 , the race inserts are inserted laterally into the grooves  116 ,  118  along a direction illustrated generally by arrow  121 . 
     The grooves  116 ,  118  further include biasing fingers  130  that support the race inserts  104 ,  105 . Prior to assembly of the guide rail  100 , the fingers  130  extend generally parallel to one another, as well as the direction of insertion, i.e. arrow  121 , and laterally outward from the base of grooves  116 ,  118 . 
     In this configuration, the fingers  130  are non-parallel with load transmission lines  112 ,  114 . 
     During mounting of the race inserts  104 ,  105 , the race inserts are inserted along the direction of arrow  121 . During this process, a sufficient force is applied to the race inserts  104 ,  105  to cause the fingers  130  to deform substantially under a state of bending. More particularly, the fingers  130  associated with a top portion of race insert  104 ,  105  bend toward the top  132  of the base rail  102  and therefore deform away from the bottom portion of a race insert  104 ,  105 . Similarly, the fingers  130  associated with a bottom portion of race insert  104 ,  105  bend toward the bottom  134  of the base rail  102  and, therefore, deform away from the top portion of the race insert  104 ,  105 . During this assembly, the fingers are cammed against the back surfaces of the race inserts  104 ,  105  to cause the fingers to bend. In other words, the tips of the fingers contact the back surface of the race inserts  104 ,  105  and then as the race inserts  104 ,  105  are continually pushed into the grooves, the fingers  130  slide along back surface of the race inserts  104 ,  105  and are bent. 
     By placing the fingers  130  in a state of bending, it is contemplated that a more controlled deformation of the fingers  130  can be accomplished. As such, tolerancing of the race ways  108 - 111  is believed to be more accurately controlled. 
     In some embodiments, the extent of bending the fingers  130  is between about 5 degrees and 35 degrees. Further, the bending may be more arcuate in nature than is illustrated in the figures. 
     With reference to  FIG. 2 , it will be noted that the configuration of the illustrated embodiment is free of undercuts between adjacent ones of the fingers  130  which can assist in the event that the fingers  130  are machined into the base rail  102 . In such an arrangement, a grinder having a rotating axis extending perpendicularly to the insertion direction  121  can be used so that all of the fingers are cut with a grinding wheel rotating in the same direction. Thus, all material for each finger will be exposed to similar machining characteristics. If undercuts were provided, the grinding wheel would have to be inserted with an axis of rotation generally parallel to insertion direction  121  such that the top portion and bottom portion of fingers  130  would be ground by opposite sides of a wheel, which can provide different machining characteristics to the fingers  130 , such as material flow directions. 
     In the illustrated embodiment, each race insert  104 ,  105  includes first, second and third back surface segments  140 ,  142 ,  144  (numbered and discussed in terms of race insert  104 ). The first and third back surface segments  140  extend at non parallel and non-perpendicular angles to second back surface segment  142 . In the illustrated embodiment, the first and third back surface segments  140 ,  144  face away from one another. 
     Prior to deformation of fingers  130  that associate with the first back surface  140 , the tips of the fingers  130  generally are aligned at an angle relative to the bottom of the channel  146  (see  FIG. 2 ) that is the same angle as the first back surface segment  144  aligns with the second back surface segment  142 . The same arrangement is true with regard to the fingers  130  that associate with the third back surface  144 . As such, a line segment passing through the bases  150 ,  152  where the fingers  130  extend from are preferably parallel to the corresponding first or third back surface segments  140 ,  144 . 
     Further, in the illustrated embodiment, no fingers  130  engage the second back surface  142 . This is because back surface  142  is generally perpendicular to insertion direction  121 . The use of fingers  130  to contact these regions would result in the fingers being axially mushroomed and placed into a state of compression rather than a state of bending as discussed previously. 
     As such, each of the fingers  130  extend laterally outward a same distance. This distance is measured on a same side of the fingers  130  in which the fingers will be bent during insertion of the race inserts  104 ,  105 . This arrangement promotes substantially constant bending forces throughout the various fingers  130  during assembly of the guide rail  100 . This constant distance is illustrated in  FIG. 2 . Further, as the fingers  130  are not compressed or mushroomed, the thickness of the fingers  130 , perpendicular to the cantilevered length of the fingers  130 , remains substantially constant even after assembly. This constant thickness is provided by the beneficial arrangement of having the fingers  130  in a state of bending rather than a state of compression further promoting more consistent loading of the race inserts  104 ,  105  by fingers  130 . 
     In the illustrated embodiment, only two fingers  130  are associated with a given back surface segment  140 ,  144 . However, in other embodiments, more or less fingers can be used depending on the length of the back surface and desired support and resistance during assembly. 
     In the illustrated embodiment, all of the fingers  130  that are associated with the first back surface segment  140  are laterally bent away from the fingers  130  that are associated with third back surface segment  140 . This is because the first, and second surfaces face away from one another. However, if a different profile, such as V-profile were used, where the fingers  130  are located internal to the V-profile, the fingers  130  associated with one back surface segment would be laterally bent toward the fingers  130  associated with the other back surface segment of the V-profile. 
     All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
     The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
     Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.