Patent Publication Number: US-8973306-B2

Title: Two-stage linked sliding door of machine tool

Description:
RELATED APPLICATIONS 
     The present application is based on, and claims priority from, Japanese Application Number 2012-040938, filed Feb. 28, 2012, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a two-stage linked sliding door of a machine tool. 
     2. Description of the Related Art 
     A machining space of a machine tool is closed by a cover to prevent chips and coolant from being scattered to the outside. In this arrangement, a sliding door may be provided for loading and unloading workpieces. 
     For large workpieces, a two-stage sliding door can be advantageously used to provide a larger door opening width. To increase production efficiency, moreover, the door must be quickly opened and closed. 
     The door opening/closing speed can be smoothly increased by installing a mechanism for associating the operations of two door halves. A mechanism comprising a wire and pulleys is a known as means for interlocking the door halves. An example of this means applied to a machine tool is disclosed in Japanese Patent Application Laid-Open No. 2006-205337. 
       FIG. 7  is a view illustrating a prior art two-stage linked sliding door of a machine tool. As shown in  FIG. 7 , plate-like door halves  1  and  2  are attached to an opening (not shown) in a fixed cover of the machine tool, the door half  1  leaving the opening open. In a mechanism using pulleys  3  and  4  and a wire  5 , the pulleys  3  and  4  are disposed individually on the opposite ends of a pulley fixing portion  6  that is secured to the door half  2  with a shorter stroke. The wire  5  is secured to the door half  1  with a longer stroke by a wire fixing portion  7 . 
     The wire  5  is secured to a door frame  8  by means of wire tensioning springs  9  and  10 . Thus, a wire tensioning spring supporting member  11  is secured to the door frame  8 . One ends  9   b  and  10   b  of the wire tensioning springs  9  and  10  are anchored to a protrusion, such as a bolt, secured to the wire tensioning spring supporting member  11 , while the other ends  9   a  and  10   a  are connected to ends  5   a  and  5   b , respectively, of the wire  5 . Since the wire ends  5   a  and  5   b  are secured to the wire tensioning spring supporting member  11  by means of the wire tensioning springs  9  and  10 , the possibility of slacking of the wire  5  due to prolonged use is obviated, and a constant tension can be maintained. In this way, the wire  5  is prevented from being disengaged from the pulleys  3  and  4 . 
     The following is a description of the operations of the door halves  1  and  2 . If the door half  1  is moved to the right in the drawing (as indicated by an arrow  101 ) to close the opening in the fixed cover, the pulley  4 , that is, the door half  2 , like the door half  1 , moves to the right in the drawing (as indicated by an arrow  102 ). Thereupon, the door halves  1  and  2  move in association with each other. The amount of movement of the door half  2  is half that of the door half  1 . 
     In the above-described arrangement shown in  FIG. 7 , the wire tensioning springs  9  and  10  lie on the same axis in the direction of movement of the door halves  1  and  2  being opened or closed, so that the length ( 100 ) of a wire tensioning portion inevitably increases. In some machine tools, a locking mechanism may be attached to their automatic or non-automatic doors. Since chips and cutting fluid are scattered during machining, mechanical sections, including an automatic door opening and closing mechanism, locking mechanism, linkage mechanism, etc., are often intensively located on the door frame  8  or the like above the door that cannot be easily affected by chips and cutting fluid. Thus, an installation space for the linkage mechanism for the door halves  1  and  2  is limited, so that the mechanical sections are expected to be reduced in size and space. 
     SUMMARY OF THE INVENTION 
     Accordingly, in view of the above problems of the prior art, the object of the present invention is to provide a two-stage linked sliding door of a machine tool, in which a door linkage mechanism can be reduced in size and space. 
     A first aspect of a two-stage linked sliding door of a machine tool according to the present invention comprises: a two-stage sliding door attached to the machine tool, the sliding door comprising a first door half movable through a predetermined stroke and a second door half movable through a stroke shorter than that of the first door half and accommodated overlapping a fixed cover of the machine tool; two pulleys disposed individually at one and the other end portions of the second door half; a wire stretched between the two pulleys; a wire tension portion which secures the opposite end portions of the wire to one of a door frame and the first door half through two elastic members individually pulling the opposite end portions of the wire in a manner such that the opposite end portions of the wire face each other; and a wire intermediate portion fixing member which secures an intermediate portion of the wire between the two pulleys to the other of the door frame and the first door half. The two elastic members are juxtaposed and offset with each other so that the respective central axes thereof do not lie on the same axis. 
     The intermediate portion fixing member may be provided with a member configured to stagger the wire or the diameter of one of the two pulleys is made larger than that of the other pulley so that the wire extends parallel to the direction of movement of the door. 
     A second aspect of a two-stage linked sliding door of a machine tool according to the present invention comprises: a two-stage sliding door attached to the machine tool, the sliding door comprising a first door half movable through a predetermined stroke and a second door half movable through a stroke shorter than that of the first door half and accommodated overlapping a fixed cover of the machine tool: two pulleys disposed individually at one and the other end portions of the second door half; and two wires passed individually around the two pulleys, one end of each of the wires being secured to a door frame and the other end to the first door half. The one or the other ends of the two wires is secured to the door frame or the first door half by means of two elastic members, and the two elastic members are juxtaposed and offset with each other so that the respective central axes thereof do not lie on the same axis. 
     Those end portions of the two wires which are secured to the door frame or the first door half without the use of the elastic members may be secured to the first door half or the door frame by means of members which partially stagger the wires so that the wires extend parallel to the direction of movement of the door. 
     According to the present invention, there can be provided a two-stage linked sliding door of a machine tool, in which a door linkage mechanism can be reduced in size and space. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects and features of the present invention will be obvious from the ensuing description of embodiments with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view illustrating a first embodiment of a two-stage linked sliding door of a machine tool according to the present invention; 
         FIG. 2  is a top view of a linkage mechanism of the sliding door shown in  FIG. 1 ; 
         FIG. 3  is a view illustrating a principal part of the linkage mechanism of the sliding door shown in  FIG. 2 ; 
         FIG. 4  is a view illustrating a second embodiment of the two-stage linked sliding door of a machine tool according to the present invention; 
         FIG. 5  is a view illustrating a third embodiment of the two-stage linked sliding door of a machine tool according to the present invention; 
         FIG. 6  is a view illustrating a fourth embodiment of the two-stage linked sliding door of a machine tool according to the present invention; and 
         FIG. 7  is a view illustrating a prior art two-stage linked sliding door of a machine tool. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A two-stage linked sliding door of a machine tool according to the present invention has a wire tensioning structure such that an installation space for wire tensioning springs attached to the ends of a wire that is stretched between two pulleys is reduced by non-coaxially arranging the springs so that the springs overlap in parallel with each other. Further, the linked sliding door has a structure such that the wire is located parallel to the direction of door operation in order to prevent any other force than a force in this direction from acting on the door. 
     A first embodiment of the two-stage linked sliding door of a machine tool according to the present invention will first be described with reference to  FIG. 1 . 
     A first door half  1  and a second door half  2  configured to open and close an opening in a fixed cover  12  that covers the machine tool are accommodated overlapping the cover  12 . 
     A wire tensioning portion  13  is secured to a door frame  8 , and a wire fixing portion  14  is secured to the first door half  1 . One end of a wire  5  is secured to the wire tensioning portion  13 , while the other end is secured to the wire tensioning portion  13  through a pulley  3 , the wire fixing portion  14 , and a pulley  4 . Thus, the opposite ends of the wire  5  are relatively secured to the wire tensioning portion  13  in a manner such that they face each other. 
     The first door half  1  performs opening/closing operation in the direction of an arrow  103 . The first and second door halves  1  and  2 , each in the form of a plate, are operated in association with each other by a linkage mechanism, which comprises the pulleys  3  and  4 , wire  5 , wire tensioning portion  13 , and wire fixing portion  14 . Thus, the first and second door halves  1  and  2  constitute the two-stage linked sliding door. The movement stroke of the second door half  2  is shorter than that of the first door half  1 , and the movement speed of the second door half  2  during opening/closing operation is half that of the first door half  1 . The wire fixing portion  14  that constitutes the linkage mechanism is an example of an intermediate portion fixing member. 
       FIG. 2  is a top view of the linkage mechanism of the sliding door shown in  FIG. 1 . The first door half  1  is a plate-like door with a long stroke, while the second door half  2  is a plate-like door with a short stroke that operates in association with the first door half  1 . The first door half  1  is fitted with the wire fixing portion  14  that fixes the wire  5 . A pulley fixing portion  6  is secured to the second door half  2 , and the pulleys  3  and  4  are mounted individually on the opposite end portions of the pulley fixing portion  6 . The wire tensioning portion  13 , which serves to fix the opposite end portions of the wire  5  by means of two wire tensioning springs  9  and  10 , is secured to the door frame  8  on the fixed cover  12  by fixing means such as bolts. Reference numeral  104  denotes a door frame opening width. 
     A principal part of the linkage mechanism of the sliding door shown in  FIG. 2  will be described with reference to  FIG. 3 . 
     As shown in  FIG. 3 , the wire fixing portion  14  is secured to the first door half  1 , and the wire tensioning portion  13  is secured to the door frame  8 . The pulley fixing portion  6  is secured to the second door half  2 , and the pulleys  3  and  4  are mounted individually on the opposite end portions of the pulley fixing portion  6 . The pulleys  3  and  4  are mounted on the pulley fixing portion  6  in such a manner that they are not located on the same axis with respect to the direction of movement for opening/closing operations of the first and second door halves  1  and  2 . 
     The wire fixing portion  14  secured to the first door half  1  comprises a wire fixing member  19  for setting the wire  5  and bolts  20  and  21  secured to the fixing member  19 . The bolts  20  and  21  are mounted on the wire fixing member  19  in such a manner that they are staggered perpendicular to the movement direction of the fixing portion for opening/closing operation. The wire  5  is stretched between the bolts  20  and  21  in such a manner that it is offset perpendicular to its central axis. In  FIG. 3 , reference numeral  106  denotes an offset width of the wire  5 . Thus, the wire  5  stretched between the bolts  20  and  21  is tightened by these bolts  20  and  21  so that it cannot move relative to the bolts  20  and  21 . 
     Further, the wire tensioning portion  13  comprises a wire tensioning spring supporting member  11  and bolts  15  and  16  for fixing the opposite end portions of the wire  5  by means of the wire tensioning springs  9  and  10 , respectively. In the wire tensioning portion  13 , as shown in  FIG. 3 , the two wire tensioning springs  9  and  10  are juxtaposed and offset with each other so that their respective central axes do not lied on the same axis. In  FIG. 3 , reference numeral  107  denotes an offset amount between the juxtaposed wire tensioning springs  9  and  10 . Since the first and second wire tensioning springs  9  and  10  in the wire tensioning portion  13  are arranged parallel to each other in their axial direction, a wire tensioning portion length  105  of the wire tensioning portion  13 , which is an installation space for the wire tensioning springs  9  and  10 , can be made shorter than in the prior art case (see reference numeral  100  of  FIG. 7 ). 
     One end portion  9   b  of the first wire tensioning spring  9  is anchored to the bolt  15 , while the other end portion  9   b  is connected to one end portion  5   a  of the wire  5 . Further, on end portion  10   b  of the second wire tensioning spring  10  is anchored to the bolt  16 , while the other end portion  10   b  is connected to the other end portion  5   b  of the wire  5 . The wire  5  extending from the one end portion  5   a  passes through a wire receiving portion  17 , the pulley  4 , the wire fixing portion  14 , the pulley  3 , and a wire receiving portion  18 , and is connected at its other end portion  5   b  to the other end portion  10   a  of the wire tensioning spring  10 . Since the wire  5  is movable along its central axis in the wire receiving portions  17  and  18 , the extension and contraction of the wire  5  can be absorbed by the wire tensioning springs  9  and  10 . 
     A second embodiment of the two-stage linked sliding door of a machine tool according to the present invention will now be described with reference to  FIG. 4 . 
     The following is a description of only those portions of the second embodiment which are different from their counterparts in the first embodiment of the present invention, so the description of the same constituent elements of the second embodiment as those of the first embodiment is omitted here, by referring to the description of the first embodiment with reference to  FIGS. 1 to 3 . 
     As shown in  FIG. 4 , the present embodiment uses two wires, that is, first and second wires  22  and  23 . Further, pins  24  and  25  are secured to a projection  26  of a first door half  1 . One end  22   a  of the first wire  22  is connected to one end of a wire tensioning spring  9   a , while the other end  22   b  is anchored to the pin  24  secured to the first door half  1 . Likewise, one end  23   a  of the second wire  23  is connected to one end of a wire tensioning spring  10   a , while the other end  23   b  is anchored to the pin  25  secured to the first door half  1 . 
     A third embodiment of the two-stage linked sliding door of a machine tool according to the present invention will now be described with reference to  FIG. 5 . 
     In the third embodiment, a wire tensioning portion  13  and a wire fixing portion  14  are attached to a first door half  1  and a door frame  8 , respectively. Since other constituent elements are the same as those of the first embodiment described with reference to  FIGS. 1 to 3 , a description of those elements is omitted. 
     A fourth embodiment of the two-stage linked sliding door of a machine tool according to the present invention will now be described with reference to  FIG. 6 . 
     In the first to third embodiments of the two-stage linked sliding door of a machine tool according to the present invention described above, the two pulleys used are given the same radius. In the fourth embodiment, however, two pulleys used are given different radii. 
     The radius of a pulley  27  (one of the two pulleys  4 ,  27 ) is made larger than that of the other pulley  4 , whereby the axial position of a wire  5  can be offset by a margin equivalent to the difference between the respective radii of the pulleys  4  and  27 . Thus, in the present embodiment, a wire fixing portion  14  need not be configured to offset the wire  5  and may be configured only to tighten and fix the wire  5 . 
     In any of the first to fourth embodiments of the two-stage linked sliding door of a machine tool according to the present invention, the wires  5 ,  22  and  23  may be replaced with ropes, cords, steel cables, belts, or chains. Further, pulleys, sprockets, etc., may be used for the pulleys  3 ,  4  and  27 , depending on the types of wires used. Furthermore, rubber-like elastic members may be used in place of the springs as the members for tensioning the wires  5 ,  22  and  23 .