Patent Publication Number: US-2021162555-A1

Title: Support structure

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2019-216603 filed on Nov. 29, 2019, the contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention: 
     The present invention relates to a support structure that supports an expandable cover. 
     Description of the Related Art 
     Japanese Laid-Open Patent Publication No. 2018-039061 discloses a support structure of a cover (bellows) that can expand and contract in the moving direction of a slide table. This support structure includes a pair of shafts arranged substantially parallel to the moving direction of the slide table, a pair of bushes provided slidably on the respective shafts, and a cover supporting member which is attached to the pair of bushes and supports a cover. 
     SUMMARY OF THE INVENTION 
     In the support structure of Japanese Laid-Open Patent Publication No. 2018-039061, in some cases, the pair of shafts are not installed in parallel. In this case, since one of the paired shafts is skewed or inclined with respect to the other, the distance between the shafts becomes uneven, so that the movable range (slidable range) of the bushes on the shafts is reduced. 
     It is therefore an object of the present invention to provide a support structure capable of suppressing the reduction of the movable range of the bushes even when the shafts are not installed in parallel. 
     An aspect of the present invention resides in a support structure for supporting an expandable cover, the support structure including: at least two shafts extending in a first direction in which the cover expands and contracts, and arranged inside the cover so as to be spaced from each other in a second direction that intersects the first direction; a bush provided on each of the at least two shafts and configured to be slidable along the shaft; and a cover support member, which includes a main part configured to support the cover, a first connection part configured to connect the main part and the bush so as not to change the relative position between the bush and the main part, and a second connection part configured to connect the main part and the bush in such a manner that the relative position between the bush and the main part can be changed. 
     According to the present invention, it is possible to suppress the reduction of the movable range of the bushes even in a case where the shafts are not installed in parallel. 
     The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a slide table device of an embodiment; 
         FIG. 2  is a schematic view of a state in which a part of the cover of  FIG. 1  is cut out; 
         FIG. 3  is a schematic view of a state in which the table and a part of the covers of  FIG. 1  is removed; 
         FIG. 4  is a schematic sectional view showing a guide rail and slide in  FIG. 3 ; 
         FIG. 5  is a schematic sectional view showing shafts, bushes and a cover support member in  FIG. 3 ; 
         FIG. 6  is a schematic view when viewed from the direction of the arrow in  FIG. 5 ; 
         FIG. 7  is a schematic sectional view showing a state when the distance between the shafts is increased; 
         FIG. 8  is a schematic sectional view showing a state when the distance between the shafts is reduced; 
         FIG. 9  is a schematic view showing a cover support member of a modification 1 from the same viewpoint as that of  FIG. 6 ; 
         FIG. 10  is a schematic view showing a cover support member of a modification 2 from the same viewpoint as that of  FIG. 6 ; 
         FIG. 11  is a schematic view showing a cover support member of a modification 3 from the same viewpoint as that of  FIG. 6 ; and 
         FIG. 12  is a schematic sectional view of shafts, bushes, and a cover support member of a modification 4. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings. 
     Embodiment 
     [Structure of Slide Table Device] 
       FIG. 1  is a schematic view of a slide table device  10 . The slide table device  10  is used for a machine tool that processes (machines) a workpiece with a tool, a measuring machine having a moving mechanism, or the like. The slide table device  10  has a movable table  12  along a first direction (x-axis direction) in which the x-axis of  FIG. 1  extends. Expandable covers  14  are provided respectively on both sides of the table  12  in the moving direction (i.e., on the x-axis positive direction side and the x-axis negative direction side). 
     The cover  14  is formed so as to have a bellows-shape and serves to prevent liquid, such as a coolant ejected to a processed portion, or foreign material such as cutting chips generated during machining, from entering the interior. The covers  14  are provided respectively on the x-axis positive direction side and the x-axis negative direction side with the table  12  interposed therebetween. The cover  14  on the x-axis positive direction side and the cover  14  on the x-axis negative direction side expand and contract along the first direction (x-axis direction) in conjunction with the movement of the table  12 . When the table  12  moves in the x-axis positive direction, the cover  14  on the x-axis positive direction side contracts along the first direction (x-axis direction) while the cover  14  on the x-axis negative direction side expands in the first direction (x-axis direction). When the table  12  moves to the negative direction side of the x-axis, the cover  14  on the x-axis negative direction side contracts along the first direction (x-axis direction) while the cover  14  on the x-axis positive direction side expands in the first direction (x-axis direction) 
       FIG. 2  is a schematic view of a state in which a part of the cover  14  of  FIG. 1  is cut out,  FIG. 3  is a schematic view of a state in which the table  12  and a part of the covers  14  of  FIG. 1  is removed, and  FIG. 4  is a schematic sectional view of a guide rail  16  and a slide  18  in  FIG. 3 . 
     The slide table device  10  includes a guide rail  16 , a slide  18 , and an oil pan  40 . The oil pan  40  is formed in a box shape with its top open. The guide rail  16  is fixed to a bottom  40   a  of the oil pan  40  (see  FIGS. 3 and 4 ). The guide rail  16  is formed so as to extend in the first direction (x-axis direction). When the guide rail  16  is viewed from the first direction (x-axis direction), the cross section of the guide rail  16  is formed in a substantially T shape (see  FIG. 4 ). The slide  18  is provided over the guide rail  16 . When the slide  18  is viewed from the first direction (x-axis direction), the slide  18  is arranged so as to straddle the upper part of the guide rail  16  (see  FIG. 4 ). The slide  18  is driven by an unillustrated driving device along the guide rail  16  in the x-axis positive direction and the x-axis negative direction. The table  12  is supported by the slide  18 . The table  12  moves integrally with the slide  18  in the x-axis positive direction side and the x-axis negative direction side. The table  12  and the slide  18  constitute a slide table  38 . 
     The slide table device  10  has a support frame  20  that encloses the outsides of the guide rail  16  and the slide  18  around the entire circumference (see  FIG. 3 ). The support frame  20  is formed as a rectangular frame shape that opens upward and downward. The support frame  20  is arranged above the oil pan  40  (see  FIG. 4 ) and is fixed to the oil pan  40  through unillustrated fixation members. The support frame  20  has a pair of side walls  20   a  opposing each other in the longitudinal direction of the support frame  20  and a pair of side walls  20   b  opposing each other in the lateral direction of the support frame  20 . 
     The x-axis positive direction side cover  14  and the x-axis negative direction side cover  14  are provided so as to straddle the outer sides of the side wall  20   b  of the support frame  20  (see  FIG. 1 ). An end of the x-axis positive direction side cover  14  that lies on the table  12  side is attached to the table  12  while the other end of the cover  14  that faces away from the table  12  is attached to a fixing plate  22  fixed to the outer surface of the side wall  20   a  of the support frame  20  (see  FIG. 2 ). An end of the x-axis negative direction side cover  14  that lies on the table  12  side is attached to the table  12  while the other end of the cover  14  that faces away from the table  12  is attached to another fixing plate  22  fixed to the outer surface of the side wall  20   a  of the support frame  20  (see  FIG. 1 ). Thus, the exteriors of the side walls  20   a  and the side walls  20   b  of the support frame  20  and the upper opening of the support frame  20  are covered with the table  12 , the covers  14 , and the fixing plates  22 . 
     [Slide Support Structure] 
     A gap is formed between the guide rail  16  and the slide  18  (see  FIG. 4 ). Hydraulic oil is supplied into the gap by an oil supply unit  30  (see  FIG. 3 ). The oil supply unit  30  is controlled by a control unit  34 , and supplies hydraulic oil into the gap between the guide rail  16  and the slide  18  at a constant pressure. This creates an oil bearing between the guide rail  16  and the slide  18 , so that the slide  18  is held in a floating state with respect to the guide rail  16 . 
     Since the guide rail  16  and the slide  18  do not directly contact each other, friction between the guide rail  16  and the slide  18  is only due to viscous resistance of the hydraulic oil. Therefore, the friction between the guide rail  16  and the slide  18  is greatly reduced as compared with the friction between the guide rail  16  and the slide  18  when rollers or the like are provided between the guide rail  16  and the slide  18 . The oil supply unit  30  includes a strainer for filtering the hydraulic oil, a pump for sending the hydraulic oil, and the like. The oil supply unit  30  draws in the hydraulic oil stored in the oil pan  40 , and supplies the hydraulic oil to the gap between the guide rail  16  and the slide  18 . The hydraulic oil that has flowed out from the gap between the guide rail  16  and the slide  18  is recirculated back to the oil pan  40  and is stored therein. 
     [Cover Support Structure] 
     The support structure of the x-axis positive direction side cover  14  and the support structure of the x-axis negative direction side cover  14  are the same, and only the support structure of the x-axis positive direction side cover  14  will thus be described. 
     Two shafts  24  are attached to the support frame  20 . The support frame  20  is a shaft support member that supports the shafts  24 . In the support frame  20 , each of the side walls  20   b  that face each other in the lateral direction of the support frame  20  has a pair of flanges FR protruding inward from the corresponding side wall  20   b.  The paired flanges FR face each other in the first direction (x-axis direction) along which the cover  14  expands and contracts. The shaft  24  is arranged between the paired flanges FR on each side wall  20   b  of the support frame  20 , and is fixed to the flanges FR so that the two shafts  24  are attached to the support frame  20 . The two shafts  24  are spaced from each other in a second direction that intersects the first direction in which the cover  14  expands and contracts, and the shafts  24  extend in the first direction. In the present embodiment, the second direction is the y-axis direction that is perpendicular to the first direction (x-axis direction) in the horizontal plane. 
     Each of the two shafts  24  is provided with a bush (bushing)  26  that can slide on the shaft  24 . Each bush  26  is attached to a cover support member  28  for supporting the cover  14 . The cover support member  28  moves along the shafts  24  together with the bushes  26 . 
     A fluid such as air is supplied between the bush  26  and the shaft  24  by a fluid supply unit  32 . The fluid supply unit  32  is controlled by the control unit  34  so as to supply a fluid between the bush  26  and the shaft  24  at a predetermined pressure. This creates a fluid bearing between the bush  26  and the shaft  24 , so that the bush  26  is held in a floating state with respect to the shaft  24 . Since the bush  26  and the shaft  24  do not come into direct contact with each other, the friction between the bush  26  and the shaft  24  is only due to the viscous resistance of the fluid. Therefore, the friction between the bush  26  and the shaft  24  is greatly reduced as compared with the friction between the bush  26  and the shaft  24  when the bush  26  and the shaft  24  are in contact with each other. The fluid supply unit  32  includes a filter for removing dust and the like from the sucked air, a pump for sending the fluid, and the like. 
     The above cover support member  28  will be described in more detail.  FIG. 5  is a schematic sectional view of the shafts  24 , the bushes  26  and the cover support member  28  in  FIG. 3 , and  FIG. 6  is a schematic view when viewed from the direction of the arrow of  FIG. 5 . The cover support member  28  has a main part  28 A, a first connection part  28 B, and a second connection part  28 C. 
     The main part  28 A is a main body portion that supports the cover  14 . The main part  28 A is attached to the cover  14  with a portion of the main part being exposed to the outside of the cover  14  (see  FIGS. 1 and 2 ). The cover  14  is divided into a first cover portion  14   a  located on the side closer to the table  12  and a second cover portion  14   b  located on the side farther from the table  12  while the aforementioned portion of the main part  28 A is located between the first cover portion  14   a  and the second cover portion  14   b.  By fixing each of the first cover portion  14   a  and the second cover portion  14   b  to the main part  28 A that is arranged between the first cover portion  14   a  and the second cover portion  14   b,  the main part  28 A is attached to the cover  14 . Here, the shape of the main part  28 A is not particularly limited. In the present embodiment, the main part  28 A is formed in the shape of a character “Π” along the outer shape of the cover  14 , and has a rectangular cross section (see  FIGS. 3 and 5 ). 
     The first connection part  28 B is a leg that supports the main part  28 A. The first connection part  28 B connects the main part  28 A and the bush  26  in such a manner that the relative position of the bush  26  with respect to the main part  28 A will not change. The bush  26  that is connected to the main part  28 A through the first connection part  28 B is one of the bushes  26  arranged on the two shafts  24 . 
     The second connection part  28 C is a leg that supports the main part  28 A. The second connection part  28 C connects the main part  28 A and the bush  26  in such a manner that the relative position of the bush  26  with respect to the main part  28 A can change. The bush  26  that is connected to the main part  28 A through the second connection part  28 C is the other of the bushes  26  arranged on the two shafts  24 . 
     The second connection part  28 C is less in rigidity and thickness than the first connection part  28 B. In the embodiment, the second connection part  28 C is a flat spring (plate spring) that can be deformed in the second direction. That is, the second connection part  28 C can be deformed in the directions approaching and separating away from the adjacent shaft  24 . 
     The main part  28 A has, formed therein, a recess portion  28 X into which an end portion of the second connection part  28 C enters. The end portion is not in contact with the wall surface of the recess portion  28 X. This configuration increases a length of the second connection part  28 C extending from the bush  26  to the main part  28 A, compared with a case where the recess portion  28 X is not formed, and hence can increase the amount of deformation of the second connection part  28 C. 
     When one of the shafts  24  is skewed or inclined with respect to the other, the distance between the two shafts  24  varies. As shown in  FIG. 7 , when the distance between the shafts  24  is larger than in the case where the two shafts  24  are arranged in parallel (two-dot chain line), the second connection part  28 C deforms so as to be away from the adjacent shaft  24 . Therefore, even if the distance between the shafts  24  increases, hindrance to the sliding operation of the bushes  26  can be alleviated. 
     On the other hand, as shown in  FIG. 8 , when the distance between the shafts  24  is smaller than in the case where the two shafts  24  are arranged in parallel (two-dot chain line), the second connection part  28 C deforms so as to come closer to the adjacent shaft  24 . Therefore, even if the distance between the shafts  24  decreases, hindrance to the sliding operation of the bushes  26  can be alleviated. 
     Thus, in the present embodiment, the relative position of the bush  26  provided on one of the two shafts  24  is not displaced with respect to the main part  28 A, while the relative position of the bush  26  provided on the other of the two shafts  24  can be changed with respect to the main part  28 A. As a result, even if one of the two shafts  24  is slanted to the other, the reduction of the movable range of the bushes  26  can be suppressed. 
     MODIFICATION 
     The above embodiment may be modified as follows. 
     Modification 1 
       FIG. 9  is a schematic view showing a cover support member  28  of a modification  1 , viewed from the same viewpoint as that of  FIG. 6 . In  FIG. 9 , the same reference numerals are allotted to the components equivalent to those described in the above embodiment. In this modification, the description overlapping with the above embodiment will be omitted. 
     In this modification, the second connection part  28 C is a flat spring (plate spring) that can be deformed in the second direction (y-axis direction) as in the above embodiment. The flat spring has one cutout portion NT formed by cutting away a portion of the spring along a third direction extending from the bush  26  toward the main part  28 A. This enables the second connection part  28 C to easily rotate and twist about the third direction, so that the degree of freedom of deformation of the second connection part  28 C is increased. 
     The third direction is preferably the z-axis direction orthogonal to both the first direction (x-axis direction) and the second direction (y-axis direction). Further, multiple cutout portions NT may be formed. When the flat spring has multiple cutout portions NT, the multiple cutout portions NT may be arranged in a row, one or more of the cutout portions NT may be arranged in each of multiple rows, or multiple cutout portions NT may be arranged in an irregular manner. 
     Modification 2 
       FIG. 10  is a schematic view showing a cover support member  28  of a modification  2 , viewed from the same viewpoint as that of  FIG. 6 . In  FIG. 10 , the same reference numerals are allotted to the components equivalent to those described in the above embodiment. In this modification, the description overlapping with the above embodiment will be omitted. 
     In this modification, the second connection part  28 C is divided by a cutout portion NT into two portions, i.e., forming rod-shaped first and second divided portions  28 C 1  and  28 C 2  which each have a rectangular cross section. The first divided portion  28 C 1  and the second divided portion  28 C 2  may have the same shape or different shapes from each other. 
     As described above, in this modification, since the second connection part  28 C is divided into the first divided portion  28 C 1  and the second divided portion  28 C 2  by the cutout portion NT, it becomes possible to facilitate twisting of the second connection part  28 C about an axis parallel to the third direction, as in the above modification 1. Therefore, it is possible to increase the degree of freedom of deformation of the second connection part  28 C. 
     Here, three or more divided portions may be formed in the second connection part  28 C. When the second connection part  28 C includes three or more divided portions, the multiple divided portions may be arranged in a row, one or two or more divided portions may be are arranged in each of multiple portions, or multiple divided portions may be arranged in an irregular manner. 
     Modification 3 
       FIG. 11  is a schematic view showing a cover support member  28  of a modification 3, viewed from the same viewpoint as that of  FIG. 6 . In  FIG. 11 , the same reference numerals are allotted to the components equivalent to those described in the above embodiment. In this modification, the description overlapping with the above embodiment will be omitted. 
     In this modification, the second connection part  28 C is a coil spring that helically extends from the bush  26  toward the main part  28 A along the third direction. Provision of the second connection part  28 C as a coil spring facilitates twisting of the second connection part  28 C about the axis extending in the third direction, as in the above modifications 1 and 2, thus making it possible to increase the degree of freedom of deformation of the second connection part  28 C. 
     Here, the second connection part  28 C may be a rod-shaped spring having a polygonal cross section such as a rectangular cross section, or a rod-shaped spring having a circular cross section including an elliptical cross section, instead of the coil spring. 
     Modification 4 
       FIG. 12  is a schematic sectional view showing shafts  24 , bushes  26  and a cover support member  28  of a modification 4. In  FIG. 12 , the same reference numerals are allotted to the components equivalent to those described in the above-described embodiment. In this modification, the description overlapping with the above embodiment will be omitted. 
     In this modification, three shafts  24  extending in the first direction in which the cover  14  expands and contracts are provided in the support frame  20  (see  FIG. 3 ) and spaced at intervals from each other. Of the three shafts  24 , the shafts  24  at both sides are fixed to respective side walls  20   b  of the support frame  20  in the same manner as in the above embodiment. Of the three shafts  24 , the middle shaft  24  is fixed, for example, to the pair of side walls  20   a  of the support frame  20 . 
     The bush  26  provided on each of the shafts  24  at both sides is connected to the main part  28 A by the second connection part  28 C, while the bush  26  provided on the middle shaft  24  is connected to the main part  28 A by the first connection part  28 B. 
     According to this modification, even if at least one of the shafts  24  at both sides is inclined with respect to the middle shaft  24 , it is possible to alleviate the hindrance to the sliding operation of the bushes  26  as in the above embodiment. As a result, the reduction of the movable range of the bushes  26  can be suppressed. Here, four or more shafts  24  may be provided. 
     Modification 5 
     In the above embodiment, the recess portion  28 X is formed in the main part  28 A. However, instead of, or in addition to, the above embodiment, the bush  26  may include, formed therein, a recess portion  28 X. 
     Modification 6 
     In the above embodiment, a fluid bearing is created between the bush  26  and the shaft  24 . However, instead of the above embodiment, a rolling bearing or a sliding bearing may be provided between the bush  26  and the shaft  24 . 
     Modification 7 
     In the above embodiment, the main part  28 A is attached to the cover  14  with a portion of the main part being exposed to the outside of the cover  14 . However, instead of the above embodiment, the main part  28 A may be attached to the cover  14  in a state where the entire main part  28 A is located inside the cover  14 . In the case of this modification, the cover  14  is not separated into the first cover portion  14   a  and the second cover portion  14   b.  The main part  28 A is attached to the cover  14  by fixing a portion of the main part  28 A located inside the cover  14  to the inner surface of the cover  14 . 
     Modification 8 
     The above embodiment and the above modifications may be arbitrarily combined as long as no technical inconsistency occurs. 
     INVENTION 
     The aspects of the invention that can be obtained from the above embodiment and modifications will be described as follows. 
     The present invention is a support structure for supporting an expandable cover ( 14 ). The support structure includes: at least two shafts ( 24 ) extending in a first direction in which the cover ( 14 ) expands and contracts, and arranged inside the cover ( 14 ) so as to be spaced from each other in a second direction that intersects the first direction; a bush ( 26 ), provided on each of the at least two shafts ( 24 ) and configured to be slidable along the shaft; and a cover support member ( 28 ). The cover support member ( 28 ) includes a main part ( 28 A) configured to support the cover ( 14 ), a first connection part ( 28 B) configured to connect the main part ( 28 A) and the bush ( 26 ) so as not to change the relative position between the bush ( 26 ) and the main part ( 28 A), and a second connection part ( 28 C) configured to connect the main part ( 28 A) and the bush ( 26 ) in such a manner that the relative position between the bush ( 26 ) and the main part ( 28 A) can be changed. 
     With the above configuration, even if the shafts ( 24 ) are not installed in parallel with each other and the distance between the two shafts ( 24 ) is accordingly uneven, i.e., not constant, displacement of the position of the bush ( 26 ) relative to the main part ( 28 A) can keep the distance substantially even, thanks to the second connection part ( 28 C). Thus, even when the shafts ( 24 ) are not installed in parallel, it is possible to suppress the reduction of the movable range of the bushes ( 26 ). 
     The second connection part ( 28 C) may be configured to be deformable at least in the second direction. This makes it possible to keep the distance between the two shafts ( 24 ) substantially even thanks to deformation of the second connection part ( 28 C). 
     The second connection part ( 28 C) may be a flat spring, and the flat spring may have a cutout portion (NT) formed by cutting away a portion of the flat spring along a third direction extending from the bush ( 26 ) to the main part ( 28 A). This configuration facilitates twisting of the second connection part ( 28 C) about the axis extending in the third direction, and hence increases the degree of freedom of deformation of the second connection part ( 28 C). 
     At least one of the main part ( 28 A) and the bush ( 26 ) may include, formed therein, a recess portion ( 28 X) which an end of a spring element of the second connection part ( 28 C) enters, and the end may be not in contact with the wall surface of the recess portion ( 28 X). This configuration makes it possible to increase the length, of the second connection part ( 28 C), from the bush ( 26 ) to the main part ( 28 A), compared to the case when no recess portion ( 28 X) is formed. As a result, the amount of deformation of the second connection part ( 28 C) can be increased. 
     The present invention is not particularly limited to the embodiment described above, and various modifications are possible without departing from the essence and gist of the present invention.