Abstract:
A reduction of the number of parts and the prevention of a gap and a difference in level from occurring in the passage route of the rollers. A slider S is provided with a pair of guide holes 31, 32 for forming a return guide path. Guide cylinders 34 in which the rollers 37 roll are inserted in the guide holes 31, 32. A pair of passage groove 42, 43 having different depth and intersecting with each other is provided in each of the end caps e1, e2. A divider frame 36 is provided integrally with one end of each guide cylinder 34 for defining the intersecting passage grooves. The divider frame 36 is inserted in a cross portion of the intersecting passage grooves, whereby the outward guide path and the return guide path are defined while still intersecting.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     This invention relates to a linear motion rolling guide unit providing guide operation by rolling rollers on four raceway faces formed in a track-rail having raceway face.  
         [0003]     2. Description of the Related Art  
         [0004]     One of the conventional linear motion rolling units of the type described above is illustrated in FIGS.  13  to  19 . The conventional unit has a pair of raceway faces formed on each side face of a track-rail R, that is, the lower raceway faces  1   a,    2   a  and the upper raceway faces  1   b,    2   b.  The lower and upper raceway faces  1   a  and  1   b,    2   a  and  2   b,  are positioned forming an approximate right angle with each other. A recessed portion  3  is formed between the lower race way face  1   a  and the upper race way face  1   b.  Likewise, a recessed portion  4  is formed between the lower raceway face  2   a  and the upper raceway face  2   b.    
         [0005]     A slider S runs on the track rail R having such raceway faces. The slider S includes end caps  5  and  6  respectively combined with the front and back ends of a casing c. The casing c and the end caps  5  and  6  straddle the track-rail R having the raceway faces, tomove along the track-rail R. The slider S is bilaterally symmetrical with respect to the axis the track-rail R having the raceway faces. Therefore, the structural elements in bilateral symmetry will be hereinafter described by use of the same reference numerals or symbols. The description is given relating only to the raceway faces  1   a  and  1   b  as a representative example.  
         [0006]     A pair of guide holes  7  and  8  is located in the casing c to extend flush with and parallel to the raceway faces  1   a  and  1   b  (and to the raceway faces  2   a  and  2   b ) formed on the track-rail R. The guide holes  7  and  8  extend through the casing c in the axis direction and are parallel to each other in upper and lower positions. Guide cylinders  9  and  10  shown in  FIG. 14  are respectively inserted into the guide holes  7  and  8 .  
         [0007]     Each of the guide cylinders  9  and  10  is made up by combining two semicircular cylinder members together. Rollers  11  and  12  roll in the respective guide cylinders  9  and  10  in a such manner as to be parallel to the respective raceway faces  1   a  and  1   b  (to the respective raceway faces  2   a  and  2   b ) . As can be seen from  FIG. 13 , the rollers  11 , after rolling in the guide cylinder  9  of the upper guide hole  7 , are guided in a direction that brings them into contact with the lower raceway face  1   a  ( 2   a ), while the rollers  12 , after rolling in the guide cylinder  10  of the lower guide hole  8 , are guided in a direction that brings them into contact with the upper raceway face  1   b  ( 2   b ) . In this manner, the rollers  11  and  12  individually alternate between the upper and lower positions during their rolling movement, and the turning points are provided in the end caps  5  and  6 .  
         [0008]     As shown in  FIG. 15 , a pair of intersecting passage grooves  13  and  14  is provided in each of the end caps  5  and  6 . The passage groove  13  is deeper than the passage groove  14 , as shown in  FIG. 16 . The passage groove  13  would obstruct the continuity of the passage groove  14 . To avoid this, abridge member  15  as illustrated in  FIG. 16  is installed across the location where the continuity is obstructed. The bridge member  15  has a U-shaped end face. As can be seen from  FIG. 16 , the bottom  15   a  is formed in an arc shape continuous with the groove portions  14   a  and  14   b  of the passage groove  14 . The U-shaped bridge member  15  rests on bridge steps  16  which are provided parallel to the passage groove  13 .  FIG. 17  illustrates the bridge member  15  on the bridge steps  16 .  
         [0009]      FIG. 17  illustrates the end cap  5 . By mounting the bridge member  15  in this manner, the groove portion  14   a,  the bottom  15   a  and the groove portion  14   b  are connected continuously to each other to form the passage groove  14 . By mounting the bridge member  15  as shown in  FIG. 17 , the passage grooves  13  and  14  are defined by the bridge member  15  and intersect with each other in a multilevel manner in a position corresponding to the bridge member  15 .  FIG. 17  further shows a cap member  17  which is mounted in a direction at right angles to the passage groove  14  and has two ends resting on supporting steps  18  as shown in  FIG. 16 .  
         [0010]     Two pairs of convexities  19  and  20  are provided on the respective ends of the passage grooves  13  and  14  which are father away from the track-rail R having the raceway faces, as shown in  FIG. 15 . A fitting recess  21  is formed between the pair of convexities  19 , and a fitting recess  22  is formed between the pair of convexities  20 . Two pairs of convexities  23  and  24  are provided one step higher up than the respective pairs of convexities  19  and  20 . The outer peripheries of the convexities  19  and  23  are combined together to form an arc shape in alignment with the outer periphery of the guide cylinder  9 , and likewise the outer peripheries of the convexities  20  and  24  are combined together to form an arc shape in alignment with the outer periphery of the guide cylinder  10 .  
         [0011]     As is clear from  FIG. 14 , projections  9   a  and  10   a  are provided at ends of the guide cylinders  9  and  10 , and designed to be tightly fitted into the respective fitting recesses  21  and  22 . By tightly fitting the projections  9   a  and  10   a  into the fitting recesses  21  and  22 , each of the guide cylinders  9  and  10  which are each made up of two members is kept in one piece. The ends of the guide cylinders  9  and  10  with the projections  9   a  and  10   a  fitted into the fitting recesses  21  and  22  are in contact with the convexities  19 ,  20  and the convexities  23 ,  24 , so that the continuity between the guide cylinders  9  and  10  and the respective passage grooves  13  and  14  is maintained.  
         [0012]     Accordingly, the rollers  11  and  12 , which have been respectively guided from the guide cylinders  9  and  10  to the passage grooves  13  and  14 , are further guided from access portions  25  and  26  which are the other ends of the passage grooves  13  and  14 , onto the lower raceway face  1   a  and the upper raceway face  1   b  of the track-rail R having the raceway faces. Alternatively, the rollers  11  and  12 , which have reached the end cap  5  or  6  from the lower raceway face la and the upper raceway face  1   b,  are then guided from the access portions  25  and  26  into the passage grooves  13  and  14 . Note that  FIG. 19  is a sectional view of the slider S straddling the track-rail R having the raceway faces.  FIG. 13  also shows a retaining plate  29  provided for preventing the rollers  11  and  12  guided from the access portions  25  and  26  as described above from falling out of the slider S.  
         [0013]      FIG. 14  also shows underside sealing members  27  that are provided for sealing the underside of the slider S for preventing the intrusion of dust and the like from the underside to the slider. In addition, end seal members  28  are provided on the outer sides of the respective end caps  5  and  6  for preventing the intrusion of dust and the like from the directions of movement of the slider.  
         [0014]     Upon the movement of the slider S along the track-rail R having the raceway faces, the rollers  11  and  12  installed in the slider S roll along move on the raceway faces  1   a  and  1   b  (and  2   a  and  2   b ) to ensure a smooth movement of the slider S. The following is the moving path of the rollers  11  and  12 .  
         [0015]     In accordance with the moving direction of the slider S, for example, the rollers  11  and  12  are introduced from the access portions  25  and  26  shown in  FIG. 15  into the passage grooves  13  and  14  or onto the raceway faces  1   a  and  1   b  (also  2   a  and  2   b ). First, the case of the rollers  11  and  12  introduced from the access portions  25  and  26  into the passage grooves  13  and  14 .  
         [0016]     Let us assume the slider S is moved and the rollers  11  are introduced from the access portion  25  and the rollers l 2  are introduced from the access portion  26  of the end cap  5  or  6  which is located to the rear of the moving direction of the slider S. The rollers  11 , after entering the access portion  25 , are guided into the passage groove  13  and then into the guide cylinder  9  that is connected to the end of the passage groove  13  opposite to the access portion  25 . Similarly, the rollers  12 , after entering the access portion  26 , are guided into the passage groove  14  and then into the guide cylinder  10  that is connected to the end of the passage groove  14  opposite to the access portion  26 . At this point, the row of rolling rollers  11  and the row of rolling rollers  12  intersect with each other on either side of the bridge member  15 , as can be seen from  FIG. 17 . This intersection of rows of the rolling rollers is represented by the rollers  11  and  12  in  FIG. 14 .  
         [0017]     The rollers  11  and  12  after having intersected with each other in one end cap  5  or  6  in this manner are guided from the passage grooves  13  and  14  through the guide cylinders  9  and  10  into the other end cap  6  or  5  that is located to the front of the moving direction of the slider S. Then, in the end cap  6  or  5  located to the front of the moving direction, the rollers  11  and  12  are introduced into the ends of the passage grooves  13  and  14  opposite to the access portions  25  and  26 . Then, the rows of rolling rollers  11  and  12  intersect with each other while moving through the passage grooves  13  and  14 .  
         [0018]     Such a conventional linear motion rolling guide unit as described above needs a large number of parts incorporated in the end caps  5  and  6 , and in addition the guide cylinders  9  and  10  are independent of these incorporated parts. In consequence, the problem of a significantly low efficiency of the assembly process for the entire unit arises. It is needless to say that another problem is the increase in the manufacturing cost for the parts because of the large number of parts.  
         [0019]     Further, when the number of parts incorporated in the end caps is large, the dimensional tolerance and the like of the parts affects the junction between the parts, and inevitably a gap and/or a difference in level easily occur at such a junction. Once the gap and/or the difference in level occur, they cause the rollers  11 ,  12  to tilt or to catch, or alternatively cause the abrasion of the guide cylinders  9 ,  10 . As a result, the smooth circulation of the rollers  11  and  12  is impeded. A problem rising for this reason is variation in the frictional resistances of the slider S to the track-rail R when the slider S runs on the track-rail R having the raceway faces.  
       SUMMARY OF THE INVENTION  
       [0020]     It is an object of the present invention to provide a linear motion rolling guide unit which has the number of junctions between parts reduced through a reduction in the number of parts in order to overcome the conventional problems.  
         [0021]     The present invention provides a linearmotion rolling guide unit which is provided with a track-rail which has two raceway faces formed on each of its two sides, and a slider which straddles and moves along the track-rail having the raceway faces and incorporates a plurality of rollers forming four endless rolling rows. In the slider, two sets of outward guide paths for guiding the respective endless rows of the rollers rolling in one direction and return guide paths for guiding the corresponding endless rows of the rollers rolling in the opposite direction are provided on each of the two sides of the track-rail having the raceway faces. The outward guide paths are parallel to the respective raceway faces. The return guide paths extend through the inside of the slider. Each of the outward guide paths and the return guide path paired therewith intersect with each other in an end cap provided in the slider.  
         [0022]     In the linear motion rolling guide unit of the present invention, the slider contains a pair of guide holes provided for forming the return guide paths. Guide cylinders in which the rollers roll are inserted in the respective guide holes. The end cap contains a pair of passage grooves having different depths and intersecting with each other. A divider frame is provided integrally with one end of each of the guide cylinders for providing apartition between the intersecting passage grooves. The divider frame is fitted into a cross portion of the passage grooves intersecting with each other, whereby the outward guide path and the return guide path are defined while still intersecting. The types of rollers described in the present invention include a cylindrical roller, a long cylindrical roller, a needle roller and the like.  
         [0023]     Further, in the linear motion rolling guide unit of the present invention, the divider frame forms a passage hole enabling the rollers which have moved through the guide cylinder to continue to roll. The outer face of the divider frame serves as a guide face for the rollers which have rolled through another guide cylinder.  
         [0024]     According to the present invention, the parts required for forming the return guide path are only the guide cylinders having the divider frames formed integrally therewith and the end caps. In other words, the required number of parts incorporated in the end cap is only one. Hence, as compared with the conventional linear motion rolling guide units, a significant reduction in the manufacturing cost is possible. A small number of parts leads to a reduction in the number of processes for assembly. In consequence, the assembly process can be simplified, which in turn aids in reducing the cost.  
         [0025]     Further, the reduced number of parts incorporated in the end cap as described above results in a reduction in the number of junctions. In consequence, the occurrence of gaps and differences in level in the junctions caused by the dimensional tolerance and the like of the parts is reduced. If the gaps and differences in level are not produced in this manner, the disadvantages of the roller tilting or catching or the abrasion of the guide cylinders are eliminated. For this reason, when the slider runs on the track-rail having the raceway faces, a stable frictional resistance of the slider to the track-rail is achieved. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]      FIG. 1  is a perspective exploded view of a slider according to the present invention.  
         [0027]      FIG. 2  is a view of an end cap when viewed from a casing.  
         [0028]      FIG. 3  is a plan view of a guide cylinder.  
         [0029]      FIG. 4  is a side view of the guide cylinder.  
         [0030]      FIG. 5  is a bottom view of the guide cylinder.  
         [0031]      FIG. 6  is a sectional view taken along the VI-VI line in  FIG. 3 .  
         [0032]      FIG. 7  is a sectional view of the guide cylinder with a divider frame mounted on the end cap.  
         [0033]      FIG. 8  is a sectional view of the guide cylinder with a step mounted on the end cap.  
         [0034]      FIG. 9  is a partial perspective view of the divider frame of the guide cylinder.  
         [0035]      FIG. 10  is a partial perspective view including a partial sectional view of a connection portion of a passage groove in the end cap.  
         [0036]      FIG. 11  is a perspective view illustrating the intersection of rows of rolling rollers with each other.  
         [0037]      FIG. 12  is a partial perspective view of the guide cylinder installed in the end cap.  
         [0038]      FIG. 13  is a perspective view with a partial sectional view illustrating a conventional linear motion rolling guide unit.  
         [0039]      FIG. 14  is a perspective exploded view of the conventional guide unit.  
         [0040]      FIG. 15  is a view of a conventional end cap when viewed from a casing.  
         [0041]      FIG. 16  is a partial perspective view including a partial sectional view of the conventional end cap.  
         [0042]      FIG. 17  is a sectional view of the conventional end cap with a cap member, taken along the line XVII-XVII line in  FIG. 15 .  
         [0043]      FIG. 18  is a perspective view of a bridge member to be incorporated in the conventional end cap.  
         [0044]      FIG. 19  is a sectional view of the conventional slider straddling a track-rail having raceway faces. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0045]      FIG. 1  to  FIG. 12  illustrate an embodiment of the present invention, in which the principal elements of a slider S are a casing c and a pair of end caps e 1  and e 2 . The slider S moves on a conventional track-rail R having raceway faces as described earlier. The structure of the casing c is practically the same as that of the conventional one. A pair of guide holes  31  and  32  is formed in each of the two side portions of the casing c. Reference numeral  33  in  FIG. 1  denotes an underside seal for preventing the intrusion of dust and the like from under the slider S.  
         [0046]     The biggest feature of the embodiment is the structure of a guide cylinder  34  incorporated in each of the guide holes  31  and  32 . The four guide cylinders  34  used here are identical in shape. All the guide cylinders are designated by the same reference numeral  34 . Eachof the guide cylinders  34  is composed of a cylinder  35  inserted into the guide hole  31  or  32 , and a divider frame  36  formed integrally with the cylinder  35 , as can be seen from  FIG. 3  to  FIG. 6 .  
         [0047]     The cylinder  35  has a hollow portion provided for allowing rollers  37  to roll therein, and enables the rollers  37  to roll in the hollow portion with the axis of each roller  37  placed at right angles to the axis of the cylinder  35 , as can be seen from  FIG. 11 . Two slits  38   a  are formed in the cylinder  35  and extend in the axis direction. A leaf spring  38  is formed between the slits  38   a.  For example, when the interval between each of the rolling rollers  37  is lessened and the regularly spacing and lining up of the rollers  37  is disturbed, the leaf spring  38  is provided for correcting the disturbed row and elastically retreating.  
         [0048]     The divider frame  36  is provided integrally with one end of the cylinder  35 , and provided with a passage hole  36   a  extending in a direction at right angles to the axis of the cylinder  35 , and with a surrounding wall  36   b  on the periphery of the passage hole  36   a,  as can be seen from FIGS.  3  to  6 . As can be seen from FIGS.  6  to  9 , a pair of projecting arms  39  is formed integrally with the surrounding wall  36   b  on the top thereof, or on an extension of the cylinder  35 . In addition,a guide piece  40  having an arc-shaped inner face is also formed integrally with the surrounding wall  36   b  at the lower end of the divider frame  36  located opposite to the projecting arms  39 . Further, as can be seen from  FIG. 6 , a step  49  is formed at the other end of the guide cylinder  34 .  
         [0049]     The end caps e 1  and e 2  provided at the respective ends of the casingare identical instructure, sothat eachof the structural elements is hereinafter described with the same reference numeral. As can be seen from  FIG. 2 , a pair of passage grooves  42  and  43  is formed in each end cap e 1 , e 2 . The passage grooves  42  and  43  intersect with each other. The groove depth of each passage groove  43  is deeper than that of each passage groove  42 . Hence,the continuity of the passage groove  42  is obstructed by the passage groove  43 . Incidentally, the description is given relating to only one of the right and left passage grooves  42  and one of the right and left passage grooves  43  in each end cap in  FIG. 2 , as a representative example.  
         [0050]     The passage groove  42  has one end serving as an access portion  42   a  and the other end serving as a connection portion  42   b.  As illustrated in  FIG. 7 , the connection portion  42   b  has a bottom face  42   c  formed in an arc shape. As illustrated in  FIG. 10 , receiving grooves  42   d  are formed on either side of the connection portion  42   b,  into which the projecting arms  39  formed in the guide cylinder  34  are respectively inserted. By inserting the projecting arms  39  into the receiving grooves  42   d,  the divider frame  36  of the guide cylinder  34  is placed in a position corresponding to a cross portion  44  between the passage grooves  42  and  43 .  
         [0051]     As shown in  FIG. 7 , the divider frame  36  is disposed at the cross portion  44 . Specifically, by disposing the divider frame  36  in a position corresponding to the cross portion  44 , the discontinuity of the passage groove  42  is reconnected through the passage hole  36   a  of the divider frame  36 , and the passage formed by the passage groove  42  and the passage formed by the passage groove  43  are defined by the surrounding wall  36   b  of the divider frame  36 . At this point, the outer periphery face of the surrounding wall  36   b  is combined with the passage groove  43  to guide the rollers  37 , thus constituting the guide face of the present invention.  
         [0052]     When the divider wall  36  of the guide cylinder  34  is fitted into each of the end caps el and e 2 , the passage groove  42  is reconnected. The connection portion  42   b  is continuous with the cylinder  35  and the access portion  42   a  is combined with the guide piece  40  to form an introducing portion  45 . As illustrated in  FIG. 12 , a guide piece  46  is formed integrally with each of the end caps el and e 2 , and forms a passage  47  which is structured to be continuous with the raceway face of the track-rail R having the raceway faces.  
         [0053]     On the other hand, the passage groove  43  also has one end serving as an access portion  43 a and the other end serving as a connection portion  43   b.  As shown in  FIG. 2  and  FIG. 8 , a step  50  is formed in the connection portion  43   b.  The bottom face  43   c  of the connection portion  43   b  is structured to be continuous with the cylinder  35 . The access portion  43   a  is continuous with a passage  48  formed by the guide piece  46  as shown in  FIG. 12 . The passage  48  is also structured to be continuous with the raceway face of the track-rail R having the raceway faces.  
         [0054]     A step  49  is formed at the other end. of the guide cylinder  34 . The step  49  is in contact with the step  50  formed in the end cap e 1  (e 2 ) as illustrated in  FIGS. 2 and 8 , in order to achieve a continuous connection between the cylinder  35  of the guide cylinder  34  and the passage groove  43 , as illustrated in  FIG. 8 .  
         [0055]     Next,the assembly process for the components will be described with reference to  FIG. 1 . Initially, the divider frame  36  of the guide cylinder  34  is fitted into each of the cross portions  44  of each of the end caps e 1  and e 2 . The guide cylinder  34  of which the divider frame  36  is thus fitted into the cross portion  44  is inserted in the guide hole  31  ( 32 ) of the casing c. The guide cylinder  34  is formed in dimensions such that the step  49  provided at the end of the guide cylinder  34  opposite the divider frame  36  projects from the casing c when it is inserted in the guide hole  31  ( 32 ). The projecting step  49  is adjoined with the step  50  of the end cap e 1  (e 2 ), such that the guide cylinder  34  communicates with the passage groove  43 .  
         [0056]     The guide groove  43  inserted in the guide hole  31  ( 32 ) constitutes the return guide path of the present invention. The area continuous with the introducing portion  45  and extending parallel to the corresponding raceway face  1   a,    1   b,    2   a  or  2   b  constitutes the outward guide path of the present invention.  
         [0057]     A plurality of rollers  37  is loaded in each of the outward guide paths and each of the return guide paths. A row of rollers  37  rolling in the guide cylinder  34  inserted in the guide hole  31  and a row of rollers  37  rolling in the guide cylinder  34  inserted in the guide hole  32  are formed. The rows of the rolling rollers  37  intersect with each other at the cross portion  44  of each of the end caps e 1  and e 2  for circulation.  
         [0058]     More specifically, for example, the rollers  37  entering the introducing portion  45  (see  FIG. 7 ) of the end cap  1   e  from the outward guide path move through the passage groove  42  while moving trough the passage hole  36   a  of the divider frame  36 . Then, the rollers  37  are guided from the connection portion  42   b  of the passage groove  42  to one end of the cylinder  35 . The rollers  37  reaching the end of the cylinder  35  move to the other end of the cylinder  35 , and are then guided from the other end of the cylinder  35  to the connection portion  43 b of the passage groove  43  formed in the other end cap e 2 , thus passing through the return guide path. The rollers  37  guided to the connection portion  43   b  of the end cap e 2  move through the passage groove  43  in the end cap e 2  and reach the introducing portion  45 . Then, the rollers  37  are guided,via the passage  48  formed in the end cap e 2 , to the corresponding raceway face  1   a,    1   b,    2   a  or  2   b,  and then pass through the outward guide path.  
         [0059]     The rollers  37 , which have moved through the outward guide path, reach the passage  47  formed in the end cap e 1 , then move to the access portion  42   a  of the end cap e 1 , and then repeat the motion through the same route. Which everway,the rollers  37  rolling between the end caps e 1  and e 2  roll through the outward guide path and the return guide path while keeping the row of rollers rolling endlessly.  
         [0060]     The rollers  37  move in the opposite direction to whichever the moving direction of the slider S is, but the moving route of the rollers  37  is the same as in the foregoing case, and it is simply the rolling direction that is different.  
         [0061]     According to the foregoing embodiment, the guide cylinder  34  is formed integrally with the divider frame  36 . Hence, the component which must be mounted in each of the end caps e 1  and e 2  is only the guide cylinder  34 . For this reason, the number of parts is significantly reduced and accordingly the number of assembly processes is reduced. If the number of assembly processes is reduced, it is needless to say that this makes a reduction in the total manufacturing cost possible.  
         [0062]     The reduction in the number of parts results in a reduction in the number of junctions between parts. In consequence, occurrence of gaps and differences in level in the junctions caused by the dimensional tolerance and the like of the parts as is found in the conventional linear motion rolling guide units is eliminated. Thus, the tilting and catching of the rollers is prevented.