Abstract:
In this rod-less cylinder equipped with a guide mechanism ( 32 ), the guide mechanism ( 32 ) has: a first rail member ( 34 ), which is attached to the sidewall of a cylinder tube ( 2 ), has an inner rolling groove ( 34   a ), and is composed of alloyed steel; a second rail member ( 36 ), which is attached to a protrusion ( 31 ) of a slider ( 27 ), has an outer rolling groove ( 36   a ), and is composed of alloyed steel; a guide path ( 38   a ) provided in the protrusion of the slider and extending parallel to the second rail member; a connection member ( 39 ) having a connection path ( 39   a ) that connects the guide path and the inner rolling groove; and a plurality of rolling bodies ( 43 ) accommodated within an endless circulation path ( 42 ) formed of the inner rolling groove, the outer rolling groove, the guide path, and the connection path.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a rod-less cylinder equipped with a guide mechanism designed to allow a slider guided by a guide mechanism to move back and forth by a moving member. 
       BACKGROUND ART 
       [0002]    Known in the past has been a rod-less cylinder equipped with a guide mechanism and comprised of a cylinder tube having a slit in an axial direction, a piston fit in the cylinder tube, a piston mount at the outside of the cylinder tube, and a piston yoke passing through the slit and connecting the piston and piston mount thereby forming a moving member, wherein the slit is closed by inside and outside seal bands, and a slider guided by a guide mechanism is made to move back and forth by the moving member. The guide mechanism, as shown in PLT 1, is comprised of sliding guide-use grooves provided at the two sides of an outer circumferential part of a round cylinder tube and balls held in ballways provided at guide arms engaged with the same. In PLT 2, there has been known a mechanism comprised of guide rails attached to top surfaces of flange parts formed at a bottom part of a cylinder and guide members attached to the inside of a bottom end of a table and engaged with the same. 
       CITATION LIST 
     Patent Literature 
       [0003]    PLT 1: Japanese Utility Model Publication No. 3-2902Y 
         [0004]    PLT 2: Japanese Patent Publication No. 2721301 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0005]    In PLT 1, when a large load is applied to the guide arms from the vertical and horizontal directions, since sliding guide-use grooves made of an aluminum material have a low limit surface pressure, the pressing force on the plurality of balls say cause dents in the grooves and other effects on the rolling motion of the balls. There is the problem that the guide arms moving along the grooves could no longer smoothly move. Further, since the grooves are formed at the outer circumference part of a round cylinder tube, the centers of the grooves became the center position of the cylinder tube in the vertical direction. However, if pressurized air is fed to the inside of the cylinder tube, the outer circumference part of the cylinder tube elastically deformed to the outside and the grooves applied load to the balls. It is not possible to reduce the load by arranging the centers of the grooves below the center position of the cylinder tube in the vertical direction. In PLT 2, it is necessary to fasten the guide rails on the top surfaces of the flange parts sticking out from the side surfaces of the cylinder in the width direction. The span of the cylinder in the width direction is larger and the position for attachment of the cylinder may be limited. Therefore, an object of the present invention, in consideration of the above problems, is to provide a rod-less cylinder equipped with a guide mechanism designed to enable a moving member to smoothly move back and forth even when a large load acts on a slider guided by a guide mechanism from the vertical or horizontal direction. 
       Solution to Problem 
       [0006]    The present invention provides a rod-less cylinder equipped with a guide mechanism, the cylinder comprising a moving member comprised of a piston fit in a cylinder hole of a cylinder tube having a slit in an axial direction, a piston mount at an outside of the cylinder tube, and a piston yoke passing through the slit to connect the piston and piston mount, wherein the slit is closed by inside and outside seal bands, and a slider guided by the guide mechanism being made to move back and forth by the moving member, 
         [0007]    characterized in that the slider is formed so as to straddle a top surface of the cylinder tube, and the guide mechanism is provided between projecting parts sticking out downward and formed at the two ends of the slider in the width direction and side walls of the cylinder tube and has first rail members attached in a longitudinal direction of the cylinder tube, forming inside rolling grooves, and comprised of alloy steel, second rail members attached to the projecting parts of the slider, forming outside rolling grooves, and comprised of alloy steel, guide paths provided at projecting parts of the slider parallel with the second rail members, connecting members forming connecting paths connecting the guide paths and inside rolling grooves, and pluralities of rolling members held inside endless circulation paths formed by the inside rolling grooves, outside rolling grooves, guide paths, and connecting paths. Furthermore, the cylinder hole formed in the cylinder tube is non-circular, and centers of the circulation paths formed by the inside rolling grooves and outside rolling grooves are arranged below the center position of the cylinder hole in a vertical direction. 
       Advantageous Effects of Invention 
       [0008]    In the present invention, when a large load acts on the slider moving due to the moving member from the vertical or horizontal direction, the load causes the pluralities of rolling members to press against the inside rolling grooves of the first rail members and the outside rolling grooves of the second rail members, but the limit surface pressures of inside and outside rolling grooves made of alloy steel are high and therefore there are no dents made in the grooves or other effects on the rolling motion or the rolling members. Accordingly, even when the load is applied, the slider can be made to smoothly move back and forth. Further, by attachment of the first rail members of the guide mechanism to the side walls of the cylinder tube, the span of the cylinder tube in the width direction does not become larger. Furthermore, since the cylinder tube is formed with a slit, while it used to be that the pressurized fluid supplied to the cylinder chamber caused the two side walls of the cylinder tube to elastically deform to the outside and apply an excessive load to the rolling members of the guide mechanism and thereby made it impossible for the slider to smoothly move and had other effects, by arranging the centers of the circulation paths formed by the inside rolling grooves and outside rolling grooves below the center position of the noncircular cylinder hole in the vertical direction, it is possible to prevent deformation of the two side walls of the cylinder tube from causing an excessive load to act on the rolling members of the guide mechanism. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0009]      FIG. 1  is a view showing a rod-less cylinder equipped with a guide mechanism of the present embodiment. 
           [0010]      FIG. 2  is a plan view of  FIG. 1 . 
           [0011]      FIG. 3  is an enlarged cross-sectional view along the line III-III of  FIG. 2 . 
           [0012]      FIG. 4  is a front view of the rod-less cylinder equipped with a guide mechanism shown in  FIG. 1  and a partially cutaway view. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0013]    A cylinder tube  2  of a rod-less cylinder  1  equipped with a guide mechanism shown in  FIG. 1  is produced by extruding or drawing a nonmagnetic material such as aluminum. The cylinder tube  2  has a substantially rectangular cross-section. The cylinder tube  2  has a noncircular cylinder hole  3  inside it and is formed with a slit  4  extending over its entire span in the longitudinal direction. At the cylinder tube  2 , as shown in  FIG. 3 , in addition to the cylinder hole  3  and slit  4 , mounting holes  5  for mounting end members are formed parallel to the cylinder hole  3 . The two end parts of the cylinder tube  2  in the longitudinal direction are closed by left and right end caps  6  shown as end members. Between the left and right end caps  6 , a cylinder chamber  7  is formed. The end caps  6  are attached by inserting large diameter parts of insert shaft parts  8  formed corresponding to the cylinder hole  3  into the cylinder hole  3  and in that state screwing in tapping screws  9  into the mounting holes  5  for end member mounting-use of the cylinder tube  2 . The insert shaft parts  8  have piston dampers  10  integrally attached to them. The piston dampers  10  and the insert shaft parts  8  form gasket grooves  11  into which cylinder gaskets  12  are fit. 
         [0014]    At the cylinder hole  3  of the cylinder tube  2 , a piston  13  comprised of a piston body  13   a  at the two ends of which piston ends  13   b  are provided is fit. Due to the piston  13 , the cylinder chamber  7  is divided into front and rear cylinder chambers  7 A,  7 B. Inside the front and rear cylinder chambers  7 A,  7 B, pressurized fluid supplied from the supply/discharge holes  14  of the end caps  6  causes the piston  13  to move back and forth. At the piston body  13   a,  a piston yoke  15  passing through the slit  4  is integrally formed. Part of the piston yoke  15  spreads to the left and right at the outside of the cylinder tube  2  to form a piston mount  16 . The piston  13 , piston yoke  15  and piston mount  16  form a moving member  17 . At the outer circumference of the bottom end of the piston mount  16 , a scraper  18  is attached over the entire circumference. This prevents entry of dust from the clearance between the top surface of the cylinder tube  2  and the bottom surface of the piston mount  16 . 
         [0015]    The inside and outside of the slit  4  are closed by the inside and outside seal bands  19 ,  20 . The inside and outside seal bands  19 ,  20  pass over the top and bottom of the piston yoke  15  and are connected at their two ends at the left and right end caps  6 . The inside and outside seal bands  19 ,  20  are elastic bands having thin thicknesses and elasticity. For example, they are comprised of steel bands or other magnetic materials. The outside seal band  20  is pulled in by magnets  21  arranged along the lengths of the two sides of the slit  4  at the top surface of the cylinder tube  2  and close the silt  4  from the outside. Except for the part through which the piston yoke  15  passes, the inside seal band  19  closes the slit  4  from the inside by magnetic attraction force and the fluid pressure applied to the cylinder chamber  7 . 
         [0016]    The left and right end caps  6  are formed with band insertion holes  22 ,  23  in which the inside and outside seal bands  19 ,  20  are respectively fit. They are also provided with pin holes  24  extending in the vertical direction and passing through the band insertion holes  22 ,  23 . In the band, insertion holes  22 ,  23 , the two ends of the inside and outside seal bands  19 ,  20  in the longitudinal direction are fit. Not shown mounting holes provided at the two ends of the inside and outside seal bands  19 ,  20  and the pin holes  24  are aligned, then mounting pins  25  are inserted into the mounting holes and pin holes  24  to thereby connect the inside and outside seal bands  19 ,  20  to the left and right end caps  6 . The left and right end caps  6  have cap covers  26  attached to them. These prevent the mounting pins  25  from being pulled out from above. 
         [0017]    At the cylinder tube  2 , a slider  27  formed so as to straddle the cylinder tube  2  is arranged. At the bottom surface side of the slider  27 , a recessed part  28  is formed. By engaging the piston mount  16  of the moving member  17  with that recessed part  28  and making the moving member  17  move back and forth, the slider  27  is made to move in the longitudinal direction of the cylinder tube  2 . At the left and right end caps  6 , shock absorbers  29  for easing the impacts at the stroke ends of the slider  27  and adjustment bolts  30  for adjusting the stop positions of the slider  27  are attached. At the two ends of the slider  27  in the width direction, projecting parts  31  are formed so as to stick out downward. Between those projecting parts  31  and the side walls of the cylinder tube  2 , a guide mechanism  32  for guiding the slider  27  along the longitudinal direction of the cylinder tube  2  is provided. 
         [0018]    The guide mechanism  32  will be explained next. At the two side walls of the cylinder tube  2 , first recessed grooves  33  are formed. First rail members  34  forming inside rolling grooves  34   a  having cross-sectional shapes of gothic arch shapes comprised of two arcs and made of alloy steel are fit in the first recessed grooves  33 . At the projecting parts  31  of the slider  27 , second recessed grooves  35  are formed at positions facing the first recessed grooves  33 . Second rail members  36  forming outside rolling grooves  36   a  of the same shapes as the inside rolling grooves  34   a  and made of alloy steel are fit in the second recessed grooves  35 . The first and second rail members  34 ,  36  of the present embodiment are formed from, for example, stainless steel as the alloy steel. The projecting parts  31  of the slider  27  are formed with through holes  37  parallel to the second recessed grooves  35 . In these through holes  37 , tubular members  38  each having a guide path  38   a  running therethrough are held. At the projecting parts  31  of the slider  27 , pairs of connecting members  39  having U-shaped connecting paths  39   a  connecting the guide paths  38   a  and the inside rolling grooves  34   a  are arranged. At the front and rear ends of the slider  27 , end plates  40  are attached by bolts  41  for abutting against the connecting members  39 . The inside rolling grooves  34   a,  outside rolling grooves  36   a,  guide paths  36   a,  and connecting paths  39   a  form endless circulation paths  42 . In these, pluralities of spherical rolling members  43  are held. The rolling members  43  can roll along the endless circulation paths  42  due to the back and forth motion of the slider  27 . 
         [0019]    Therefore, the guide mechanism  32  has the first rail members  34  attached to the cylinder tube  2 , forming the inside rolling grooves  34   a,  and made of alloy steel, the second rail members  36  attached to the slider  27 , forming the outside rolling grooves  36   a,  and made of alloy steel, the guide paths  38   a  provided at the projecting parts  31  of the slider  27  parallel with the second rail members  36 , the connecting members  39  forming the connecting paths  39   a  connecting the guide paths  38   a  and the inside rolling grooves  34   a,  and the pluralities of rolling members  43  held in the endless circulation paths  42  formed by the inside rolling grooves  34   a , outside rolling grooves  36   a,  guide paths  38   a,  and connecting paths  39   a.  In the rod-less cylinder  1  equipped with the guide mechanism, when a large load F acts on the slider  27  moved by the moving member  17  from the vertical or horizontal directions, that load F causes the pluralities of rolling members  43  to press against the inside rolling grooves  34   a  of the first rail members  34  and the outside rolling grooves  36   a  of the second rail members  36 . In comparison with the limit surface pressures of grooves formed by a conventional aluminum material, the limit surface pressures of the inside and outside rolling grooves  34   a,    36   a  formed by alloy steel are high, so there is no denting of the grooves  34   a,    36   a  or other effects on the rolling motion of the rolling members  43 . Accordingly, even if the load F is applied, it becomes possible to make the slider  27  (moving member  17 ) smoothly move back and forth. 
         [0020]    By attaching the first rail members  34  of the guide mechanism  32  to the side walls of the cylinder tube  2 , there is no need to provide flange parts sticking out in the width direction of the cylinder tube  2  like in the past and the cylinder tube  2  does not become greater in span in the width direction. Furthermore, since a cylinder tube  2  is formed with a slit  4 , it used to be that the pressurized fluid supplied to a cylinder chamber  7  caused the two side walls of the cylinder tube  2  to elastically deform to the outside and apply an excessive load to rolling members  43  of guide mechanism  32  and thereby made it impossible for slider  27  (moving member  17 ) to smoothly move and had other effects. On the other handy in the present embodiment, by arranging the centers of the circulation paths  40  formed by the inside rolling grooves  34   a  and outside rolling grooves  36   a  below the center position of the noncircular cylinder hole  3  in the vertical direction, the guide mechanism  32  is provided at a position further away from the slit  4  than in the past so deformation of the two side walls of the cylinder tube  2  no longer causes an excessive load to act on the rolling members  43  of the guide mechanism  32 . 
       REFERENCE SIGNS LIST 
       [0021]      1 . rod-less cylinder equipped with guide mechanism 
         [0022]      2 . cylinder tube 
         [0023]      3 . cylinder hole 
         [0024]      4 . slit 
         [0025]      13 . piston 
         [0026]      15 . piston yoke 
         [0027]      16 . piston mount 
         [0028]      17 . moving member 
         [0029]      27 . slider 
         [0030]      31 . projecting part 
         [0031]      32 . guide mechanism 
         [0032]      34 . first rail member 
         [0033]      34   a . inside rolling groove 
         [0034]      36 . second rail member 
         [0035]      36   a . outside rolling groove 
         [0036]      38   a . guide path 
         [0037]      39   a . connecting path 
         [0038]      42 . circulation path 
         [0039]      43 . rolling member