Abstract:
A tool changer configured so that a turret is turned to index a desired tool to change the tool is provided with front and rear covers that cover front and rear surfaces, respectively, of the turret. A projection or a recess, which defines a passage for chips or a cutting fluid, is formed on or in an outer peripheral portion of the rear cover. Thus, the chips produced during machining and the cutting fluid used in the machining can be prevented from getting into the turret through a gap between the front and rear covers.

Description:
RELATED APPLICATIONS 
     The present application claims priority to Japanese Application Number 2013-215607, filed Oct. 16, 2013, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a tool changer provided with covers configured to prevent extraneous matter from getting into a turret. 
     Description of the Related Art 
     A tool changer is conventionally used to automatically change a tool to be mounted on the spindle of a machine tool. This tool changer is previously fitted with a plurality of necessary work tools such that the tool to be mounted on the machine tool spindle can be automatically replaced with a specified one, depending on the machining state. 
     Japanese Patent Application Laid-Open No. 2010-99766 discloses a machine tool provided with such an automatic tool changer for automatically changing a tool. This tool changer comprises a turret provided with a plurality of grips for gripping the tool. 
     The automatic tool changer comprises the turret fitted with a plurality of tools such that the turret can be indexed to change the tool mounted on the spindle, whereby the tool can be changed rapidly and accurately. Since the front side of the turret and a turret base are only connected at a distance from each other, however, chips produced during machining and a cutting fluid may possibly get into the turret. 
     In some cases, therefore, the turret may be provided with cover means that prevents the chips and cutting fluid from getting into the turret during workpiece machining.  FIG. 11  shows a prior art example of a machine tool furnished with a tool changer comprising such cover means. 
     In  FIG. 11 , an automatic tool changer  2  attached to a machine tool  1  comprises a spindle  3  and a spindle motor  5  for driving the spindle  3 . A tool  4  is mounted on the distal end portion of the spindle  3 . Further, a Z-axis motor  11  is connected to the spindle  3  by a Z-axis ball screw  10 , and the spindle  3  can be driven vertically by the Z-axis motor  11 . Furthermore, a turret  6  is provided as a member for changing the tool  4 . 
     The turret  6  is provided with a front cover  61  and a rear cover  62  that eliminate adverse affects on structural parts (not shown) in the turret  6 . The front and rear covers  61  and  62  serve to prevent penetration of the chips and cutting fluid from the front and rear sides, respectively, of the turret  6 . 
     Depending on the shape of the rear cover  62 , chips and the cutting fluid may easily accumulate on an upper part (corresponding to region A of  FIG. 11 ) of a cylindrical portion  64  of the rear cover  62 . In changing the tool  4 , the spindle  3  is driven vertically by the Z-axis motor  11 . Since the spindle  3  is provided with a cam  7 , the turret  6  is swung by a cam follower  8  that follows the cam  7  as the spindle  3  is moved vertically. As the turret  6  is swung in this manner, chips and the cutting fluid deposited on the upper part (regions A) of the cylindrical portion  64  of the rear cover  62  move along path B shown in  FIG. 11 , and inevitably get into the turret  6  through a gap  65  between the front and rear covers  61  and  62 . Consequently, the structural parts in the turret  6  may be adversely affected. 
     SUMMARY OF THE INVENTION 
     Accordingly, the object of the present invention is to provide a tool changer of a machine tool, comprising covers configured to prevent chips and a cutting fluid from getting into a turret. 
     A tool changer according to the present invention comprises a turret with a plurality of grips for holding a tool such that the turret is turned to index a desired tool to change the tool. The tool changer comprises a front cover which covers a front surface of the turret and a rear cover which covers a rear surface of the turret. A projection or a recess, which defines a passage for chips or a cutting fluid, is formed on or in at least a part of an outer peripheral portion of the front cover and/or the rear cover. 
     According to the present invention, chips produced during workpiece machining and the cutting fluid used in the machining are dropped along the projection or recess on or in the outer peripheral portion of the rear cover (or front cover), so that they can be prevented from getting into the turret through a gap between the front and rear covers. 
     According to the present invention, there can be provided a tool changer of a machine tool, comprising cover means configured to prevent chips and a cutting fluid from getting into a turret. 
    
    
     
       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 schematic side view of a machine tool provided with a first embodiment of a tool changer according to the present invention; 
         FIG. 2  is a diagram illustrating how a cutting fluid deposited on an upper part of a cylindrical portion of a rear cover of the tool changer flows in the directions of arrows C and D; 
         FIG. 3  is a diagram illustrating a first modification of the first embodiment ( FIG. 1 ) of the tool changer; 
         FIG. 4  is a diagram illustrating a second modification of the first embodiment ( FIG. 1 ) of the tool changer; 
         FIG. 5  is a diagram illustrating a third modification of the first embodiment ( FIG. 1 ) of the tool changer; 
         FIG. 6  is a diagram illustrating an example in which a recess is also provided in an upper part of an outer peripheral portion of a front cover of the tool changer of  FIG. 4  in which a recess is provided in an upper part of an outer peripheral portion of the rear cover; 
         FIG. 7  is a schematic side view of a machine tool provided with a second embodiment of the tool changer according to the present invention; 
         FIG. 8  is a diagram illustrating a first modification of the second embodiment ( FIG. 7 ) of the tool changer; 
         FIG. 9  is a diagram illustrating a second modification of the second embodiment ( FIG. 7 ) of the tool changer; 
         FIG. 10  is a diagram illustrating a third modification of the second embodiment ( FIG. 7 ) of the tool changer; and 
         FIG. 11  is a schematic side view of a machine tool provided with a prior art tool changer. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First, a first embodiment of a tool changer according to the present invention will be described with reference to  FIG. 1 . 
     The tool changer of this embodiment differs from the prior art tool changer shown in  FIG. 11  in that a recess  66  with a semicircular cross-section is provided in an upper part (corresponding to region A of  FIG. 11 ) of an outer peripheral portion of a rear cover  62 , as shown in  FIG. 1 . Thus, chips produced as a workpiece is machined and a cutting fluid used in machining the workpiece are guided left and right relative to a front cover  61 , as indicated by arrows C and D in  FIG. 2 , so that they can be prevented from getting into a turret  6  through a gap  65  defined between the front and rear covers  61  and  62 . 
     The turret  6  is provided with a plurality of grips for holding a tool  4 . 
     In changing the tool  4 , a spindle  3  is driven to move vertically by a Z-axis motor  11 . Since the spindle  3  is provided with a cam  7 , the turret  6  is swung by a cam follower  8  that follows the cam  7  as the spindle  3  is moved vertically. As the turret  6  is swung in this manner, chips deposited on the upper part of the outer peripheral portion of the rear cover  62  and the collected cutting fluid flow along the semicircular-profiled recess  66  and are dropped outside the turret  6 . 
     Thus, the chips and the cutting fluid can be prevented from getting into the turret  6  and affecting structural parts (not shown) in the turret  6 . 
     Some modifications of the first embodiment ( FIG. 1 ) of the tool changer will be described with reference to  FIGS. 3 to 5 . 
     A first modification differs from the first embodiment ( FIG. 1 ) in that the cross-section of a recess  67  provided in the upper part of the outer peripheral portion of the rear cover  62  is U-shaped, as shown in  FIG. 3 . A second modification differs from the first embodiment in that the cross-section of a recess  68  provided in the upper part of the outer peripheral portion of the rear cover  62  is V-shaped, as shown in  FIG. 4 . Further, a third modification differs from the first embodiment in that the cross-section of a recess  69  provided in the upper part of the outer peripheral portion of the rear cover  62  is trapezoidal, as shown in  FIG. 5 . 
     In the first to third modifications described above, the recesses  67  to  69  have the same functions as the recess  66  of the first embodiment. Specifically, chips produced as a workpiece is machined and a cutting fluid used in machining the workpiece are guided left and right relative to the front cover  61 , as indicated by arrows C and D in  FIG. 2 , so that they can be prevented from getting into the turret  6  through the gap  65  defined between the front and rear covers  61  and  62 . 
     In the first embodiment and its modifications, as described above, the cross-section of the recess provided in (at least the upper part of) the outer peripheral portion of the rear cover  62  is assumed to be semicircular ( FIG. 1 ), U-shaped ( FIG. 3 ), V-shaped ( FIG. 4 ), or trapezoidal ( FIG. 5 ). However, the cross-section of the recess may be of any other shape that enables the chips produced as the workpiece is machined and the cutting fluid used in machining the workpiece to be guided left and right (in the directions indicated by arrows C and D in  FIG. 2 ). 
     In the first embodiment ( FIG. 1 ) and its modifications ( FIGS. 3 to 5 ), moreover, the recess is provided only in the upper part of the outer peripheral portion of the rear cover  62 . Alternatively, however, the recess may be provided so that it covers the entire circumference of the outer peripheral portion of the rear cover  62 . As shown in  FIG. 6 , moreover, recesses may be provided individually in the front cover  61  and the upper part of the outer peripheral portion of the rear cover  62 .  FIG. 6  shows an example in which the recess  68  is provided in the upper part of the outer peripheral portion of the rear cover  62 , and a recess  72  is provided in the upper part of the outer peripheral portion of the front cover  61 . 
     A second embodiment of the tool changer according to the present invention will now be described with reference to  FIG. 7 . 
     The tool changer of this embodiment differs from the tool changer of the first embodiment in that a projection is provided in place of the recess on an upper part (corresponding to region A of  FIG. 11 ) of an outer peripheral portion of a rear cover  62 . 
     In this embodiment, a projection  70  with a triangular cross-section is provided on the upper part of the outer peripheral portion of the rear cover  62 . Thus, chips produced as a workpiece is machined and a cutting fluid used in machining the workpiece are guided left and right relative to a front cover  61 , as indicated by arrows C and D in  FIG. 2 , so that they can be prevented from getting into a turret  6  through a gap  65  defined between the front and rear covers  61  and  62 . 
     In changing the tool  4 , a spindle  3  is driven to move vertically by a Z-axis motor  11 . Since the spindle  3  is provided with a cam  7 , the turret  6  is swung by a cam follower  8  that follows the cam  7  as the spindle  3  is moved vertically. As the turret  6  is swung in this manner, chips deposited on the upper part of the outer peripheral portion of the rear cover  62  and the collected cutting fluid flow along the triangular-profiled projection  70  and are dropped outside the turret  6 . Thus, the chips and the cutting fluid can be prevented from getting into the turret  6  and affecting structural parts in the turret  6 . 
     One modification of the second embodiment ( FIG. 7 ) of the tool changer will be described with reference to  FIG. 8 . 
     This modification differs from the second embodiment ( FIG. 7 ) in that the cross-section of a projection  71  provided on the upper part of the outer peripheral portion of the rear cover  62  is trapezoidal, instead of being triangular, as shown in  FIG. 8 . 
     In this modification, the projections have the same functions as that of the second embodiment. Specifically, chips produced as a workpiece is machined and a cutting fluid used in machining the workpiece are guided left and right relative to the front cover  61 , as indicated by arrows C and D in  FIG. 2 , so that they can be prevented from getting into the turret  6  through the gap  65  defined between the front and rear covers  61  and  62 . 
     In the second embodiment and its modifications, as described above, the cross-section of the projection provided on (at least the upper part of) the outer peripheral portion of the rear cover  62  is assumed to be triangular or trapezoidal. However, the cross-section of the projection may be of any other shape that enables the chips produced as the workpiece is machined and the cutting fluid used in machining the workpiece to be guided left and right (in the directions indicated by arrows C and D in  FIG. 2 ). 
     In the second embodiment ( FIG. 7 ) and its modification ( FIG. 8 ), moreover, the projection is provided only on the upper part of the outer peripheral portion of the rear cover  62 . Alternatively, however, the projection may be provided so that it covers the entire circumference of the outer peripheral portion of the rear cover  62 , as shown in  FIG. 9 . Instead of providing the projection on the outer peripheral portion of the rear cover  62 , moreover, a projection may be provided on the outer peripheral portion of the front cover  61  or projections may be provided individually on the respective outer peripheral portions of the front and rear covers  61  and  62 , as shown in  FIG. 10 . Alternatively, furthermore, a recess may be provided in one of the outer peripheral portions of the front and rear covers  61  and  62 , and a projection on the other.