Abstract:
A tool changer comprises a turret with a plurality of grips for holding tools such that the turret is turned to index a desired tool to change the tools. The front and rear surfaces of the turret are covered by front and rear covers, respectively. A projection or a recess which defines a passage for cutting fluid is formed in an outer rear surface portion of the rear cover at portions above and/or on each lateral side of a turret mechanism portion.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a tool changer with cover means configured to prevent foreign matter from getting into a turret. 
         [0003]    2. Description of the Related Art 
         [0004]    Tool changers are conventionally used to automatically change tools to be mounted on the spindle of a machine tool. A plurality of necessary work tools are previously set on this tool changer so that a tool specified for replacement in accordance with the machining state can be automatically mounted on the spindle of the machine tool. 
         [0005]    Japanese Patent Applications Laid-Open Nos. 2010-99766, 5-38651, 6-739 and 2006-123116, Japanese Patent No. 3990441, etc., each disclose an example in which a machine tool is fitted with one such automatic tool changer for automatically changing tools. This tool changer comprises a turret with a plurality of grips for gripping the tools. 
         [0006]    Conventionally, a turret is provided with cover means that prevents chips and cutting fluid from getting into the turret during workpiece machining.  FIG. 11  shows an example of a conventional technique in which a tool changer comprising the turret with the cover means is attached to a machine tool. 
         [0007]    In  FIG. 11 , a tool (not shown) is mounted on the distal end portion of a spindle  2  of a machine tool  1 . Further, a Z-axis motor  3  is connected to the spindle  2  by a Z-axis ball screw so that the spindle  2  can be driven vertically by the Z-axis motor  3 . Furthermore, the tool changer is provided with a turret  6  for use as a member for changing the tool. 
         [0008]    The spindle  2  is provided with a turret cam  4  and a cam follower  5 , whereby the angle of the turret  6  can be changed. The turret  6  comprises a turret mechanism portion  604  and a turret-inside mechanism portion  606 , whereby the turret  6  can be rotated. 
         [0009]    Further, a front cover  601  and a rear cover  602  are provided on the front and rear sides, respectively, of the turret  6 , in order to prevent chips and cutting fluid from getting into the turret-inside mechanism portion  606  and adversely affecting it. The rear cover  602  comprises a truncated-cone portion  605  and an outer rear surface portion  603  behind it. 
         [0010]    Since the turret cam  4  is provided on the spindle  2  in this tool changer, the turret  6  is subjected to a swinging motion by the cam follower  5  that follows the turret cam  4  as the Z-axis motor  3  is driven to move the spindle  2  vertically. 
         [0011]    In the conventional automatic tool changers disclosed in the patent documents described above, the turret is fitted with a plurality of tools and is indexed to change a tool mounted on the spindle, so that the tool change can be performed rapidly and accurately. Since the front side of the turret and a turret base are only connected by simply providing a gap between them, the cutting fluid and chips produced during machining may possibly get into various parts of the turret and adversely affect them. 
         [0012]    According to the conventional technique shown in  FIG. 11 , moreover, chips produced as a workpiece is machined and cutting fluid used in the machining may sometimes drop along the outer rear surface portion  603  of the rear cover  602  and get into the turret mechanism portion  604 . When the turret  6  is swung, furthermore, the chips and cutting fluid collected on an upper part of the truncated-cone portion  605  of the rear cover  602  may get into the turret mechanism portion  604  in the same way. 
         [0013]    Thus, in some cases, the rear cover of the conventional technique may not be able to fully prevent the chips and cutting fluid from getting into the turret mechanism portion  604 . 
       SUMMARY OF THE INVENTION 
       [0014]    Accordingly, the object of the present invention is to provide a tool changer attached to a machine tool and comprising cover means configured to prevent chips and cutting fluid from getting into a turret mechanism portion. 
         [0015]    A tool changer according to the present invention comprises a turret with a plurality of grips for holding tools such that the turret is turned to index a desired tool to change the tools. The tool changer comprises a front cover which covers a front surface of the turret, a rear cover which comprises an outer rear surface portion and covers a rear surface of the turret, a drive source for turning the turret, and a turret mechanism portion configured to transmit a force from the drive source, thereby turning the turret. The outer rear surface portion of the rear cover is formed with a projection and/or a recess which defines a flow passage on an upper side of, or on a left and right sides of, the turret mechanism portion. 
         [0016]    According to the tool changer of the present invention, the rear cover of the turret is provided with the projection and/or the recess which defines the flow passage, so that chips and cutting fluid adhering to the rear cover of the turret become liable to drop along the flow passage and can be prevented from flowing on the outer rear surface of the rear cover and getting into the turret mechanism portion. 
         [0017]    In a machine tool of the type in which the turret is swung during tool change, even when chips produced as a workpiece is machined and used cutting fluid are collected on the upper side of the rear cover, they are guided along the passage by the swinging motion during the tool change. Thus, the chips and cutting fluid can be kept from getting into the turret mechanism portion. 
         [0018]    The passage may be shaped so as to outwardly extend left and right from a transversely central portion of the rear cover as viewed from the front. 
         [0019]    Since the passage is shaped so as to outwardly extend left and right from the transversely central portion of the rear cover as viewed from the front, according to this aspect, chips and cutting fluid flow outward as they drop along the passage. Thus, the chips and cutting fluid can be more effectively prevented from getting into the turret mechanism portion. 
         [0020]    The cross-sectional shape of the projection or recess may be semicircular, triangular, or square. 
         [0021]    According to the present invention, there can be provided a tool changer attached to a machine tool and comprising cover means configured to prevent chips and cutting fluid from getting into a turret mechanism portion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    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: 
           [0023]      FIG. 1  is a schematic view showing an example of a rear cover constituting a turret of a first embodiment of a tool changer according to the present invention; 
           [0024]      FIG. 2  is a schematic view showing a first modification of the rear cover shown in  FIG. 1 ; 
           [0025]      FIG. 3  is a schematic view showing a second modification of the rear cover shown in  FIG. 1 ; 
           [0026]      FIG. 4  is a schematic view showing a third modification of the rear cover shown in  FIG. 1 ; 
           [0027]      FIG. 5  is a schematic view showing a fourth modification of the rear cover shown in  FIG. 1 ; 
           [0028]      FIG. 6  is a schematic view showing a fifth modification of the rear cover shown in  FIG. 1 ; 
           [0029]      FIGS. 7A to 7H  are views showing examples of cross-sectional shapes different from those of projections formed on the rear covers shown in  FIGS. 1 to 6 ; 
           [0030]      FIG. 8  is a schematic view showing an example of a rear cover constituting a turret of a second embodiment of the tool changer according to the present invention; 
           [0031]      FIG. 9  is a schematic view showing a first modification of the rear cover shown in  FIG. 8 ; 
           [0032]      FIGS. 10A to 10D  are schematic views showing a second modification of the rear cover shown in  FIG. 8 ; 
           [0033]      FIG. 11  shows an example of a conventional technique in which a tool changer comprising a turret with cover means is attached to a machine tool; and 
           [0034]      FIG. 12  is a view showing a rear cover constituting a turret of the tool changer of  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0035]    A first embodiment of a tool changer according to the present invention will first be described with reference to  FIGS. 1 to 6 . 
         [0036]      FIG. 1  is a view showing an example of a rear cover  602  constituting a turret of the first embodiment of the tool changer according to the present invention. A projection  607  is provided on an upper part of an outer rear surface portion  603  of the rear cover  602 . The projection  607  is semicircular in cross-section, arranged so that its central portion is higher than its opposite end portions, and inverted V-shaped as a whole. Thus, chips and cutting fluid drop along a flow passage defined by the outer rear surface portion  603  and the projection  607  of the rear cover  602 , as indicated by arrows C and D in  FIG. 1 , so that they can be prevented from getting into a turret mechanism portion  604 . Also if the chips and cutting fluid are collected on an upper part of an outer truncated-cone portion  605  of the rear cover  602 , in the tool changer of the type in which the turret  6  is swung during tool change, they drop along the passage indicated by arrows C and D in  FIG. 1 , so that they can be prevented from getting into the turret mechanism portion  604 . 
         [0037]    As described above,  FIG. 1  shows the example in which the projection  607  having the semicircular cross-section is formed in the shape of an inverted V on the upper part of the outer rear surface portion  603  of the rear cover  602 . However, the projection  607  is not limited to this shape and some modifications, such as those shown in  FIGS. 2 to 6 , can be effected. 
         [0038]    In a first modification of the rear cover  602 , as shown in  FIG. 2 , a projection  608  having a semicircular cross-section is formed on the upper part of the outer rear surface portion  603  so that its central portion is higher than its opposite end portions, and is curved as a whole. Also in this modification, chips and cutting fluid drop outward from the central portion of the rear cover  602  (or the outer rear surface portion  603 ), so that they can be prevented from getting into the turret mechanism portion  604 . 
         [0039]    In a second modification of the rear cover  602 , as shown in  FIG. 3 , a projection  609  having a square cross-section is formed on the upper part of the outer rear surface portion  603  so that its upper side extends horizontally and its left and right sides continuous with the upper side are declined, and is trapezoidal as a whole. Also in this modification, chips and cutting fluid drop downward along the left and right sides from the upper side of the projection  609  of the outer rear surface portion  603  of the rear cover  602  after they are temporarily collected on the upper side. Thus, the chips and cutting fluid can be prevented from getting into the turret mechanism portion  604 . 
         [0040]    In a third modification of the rear cover  602 , as shown in  FIG. 4 , an inverted U-shaped projection  610  is formed on the upper part of the outer rear surface portion  603  so as to enclose the upper, left, and right sides of the turret mechanism portion  604  (see  FIG. 12 ). In this modification, chips and cutting fluid outwardly drop left and right from the central portion of the projection  610  of the outer rear surface portion  603  of the rear cover  602  (or a curved portion of the projection  610  above the turret mechanism portion  604 ). Thereafter, they are dropped along the rear cover  602  by left and right straight portions of the projection  610  (or straight portions located individually on the left and right of the turret mechanism portion  604 ). Thus, the chips and cutting fluid can be prevented from getting into the turret mechanism portion  604 . 
         [0041]    In a fourth modification of the rear cover  602 , as shown in  FIG. 5 , a projection  611  on the upper part of the outer rear surface portion  603  comprises an inverted V-shaped first portion located above the turret mechanism portion  604  and straight second portions located individually on the left and right of the turret mechanism portion  604 . The projection  611  has substantially the same function as that of the third modification of the rear cover  602  ( FIG. 4 ). 
         [0042]    In a fifth modification of the rear cover  602 , as shown in  FIG. 6 , a projection  612  is provided also on the truncated-cone portion  605  of the rear cover  602  shown in  FIG. 4  (third modification). Specifically, the rear cover  602  is provided with an inverted U-shaped projection (first projection  610 ) identical to that shown in  FIG. 4  on the upper part of the outer rear surface portion  603  and a projection (second projection  612 ) on the upper part of the truncated-cone portion  605 . In this modification, chips and cutting fluid dropped on the truncated-cone portion  605  of the rear cover  602  are guided to the first projection  610  by a flow passage defined by the second projection  612  and then outwardly drop left and right from the central portion of the first projection  610 . Thus, the chips and cutting fluid can be prevented from getting into the turret mechanism portion  604 . 
         [0043]    The projections  608  and  609  formed on the outer rear surface portion  603  of the rear cover  602  shown in  FIGS. 2 and 3  are semicircular or square in cross-section. However, the cross-sections of these projections are not limited to such shapes and may also be of various other shapes, as shown in  FIGS. 7A to 7H . 
         [0044]    Projections shown in  FIGS. 7A and 7F  are shaped so that a portion having a square cross-section projects outward from a cover material. Projections shown in  FIGS. 7B and 7C  are shaped so that a portion having a triangular cross-section projects outward from a cover material. Projections shown in  FIGS. 7D and 7G  are shaped so that a portion having a trapezoidal cross-section projects outward from a cover material. Projections shown in  FIGS. 7E and 7H  are shaped so that a portion having a semicircular cross-section projects outward from a cover material. The projections of the various cross-sectional shapes shown in  FIGS. 7A to 7H  on the outer rear surface portion  603  of the rear cover  602 , like the projections of the shapes shown in  FIGS. 1 to 6 , can prevent chips and cutting fluid from getting into the turret mechanism portion  604 . 
         [0045]    A second embodiment of the tool changer according to the present invention will now be described with reference to  FIGS. 8 to 10 . 
         [0046]      FIG. 8  is a view showing an example of a rear cover  602  constituting a turret of the second embodiment of the tool changer according to the present invention. A recess  613  is provided in an upper part of an outer rear surface portion  603  of the rear cover  602 . The recess  613  is semicircular in cross-section, arranged so that its central portion is higher than its opposite end portions, and inverted V-shaped as a whole. Thus, chips and cutting fluid drop along a flow passage defined by the outer rear surface portion  603  and the recess  613  of the rear cover  602 , as indicated by arrows E and F in  FIG. 8 , so that they can be prevented from getting into a turret mechanism portion  604 . Also if the chips and cutting fluid are collected on an upper part of a truncated-cone portion  605  of the rear cover  602 , in the tool changer of the type in which the turret  6  is swung during tool change, they drop along the passage indicated by arrows E and F in  FIG. 8 , so that they can be prevented from getting into the turret mechanism portion  604 . 
         [0047]      FIG. 9  shows a modification of the recess  613  shown in  FIG. 8 . A first recess  614 , like the recess  613  of  FIG. 8 , is semicircular in cross-section, and comprises a first portion, which is arranged so that its central portion is higher than its opposite end portions and is inverted V-shaped as a whole, and straight second portions located individually on the left and right of the turret mechanism portion  604 . Further, a second recess  615  is formed on the upper part of the truncated-cone portion  605  of the rear cover  602 . In this modification, chips and cutting fluid dropped on the truncated-cone portion  605  of the rear cover  602  are guided to the first recess  614  by a passage defined by the second recess  615  and then drop outward from the central portion of the first recess  614 . Thus, the chips and cutting fluid can be prevented from getting into the turret mechanism portion  604 . Furthermore, a suitable modification may be made such that the first portion of the first recess  614 , which is arranged so that its central portion is higher than its opposite end portions and is inverted V-shaped as a whole, and the straight second portions located individually on the left and right of the turret mechanism portion  604  are formed continuously with each other or that the second recess  615  of the truncated-cone portion  605  is omitted. 
         [0048]    The recesses  613  and  614  formed in the outer rear surface portion  603  of the rear cover  602  shown in  FIGS. 8 and 9  are semicircular in cross-section. However, the cross-sections of these recesses are not limited to this shape and may also be of various other shapes, as shown in  FIGS. 10A to 10D . 
         [0049]    A recess shown in  FIG. 10A  is formed by inwardly extruding a portion having a triangular cross-section from a cover material. A recess shown in  FIG. 10B  is formed by inwardly extruding a portion having a square cross-section from a cover material. A recess shown in  FIG. 10C  is formed by inwardly extruding a portion having a semicircular cross-section from a cover material. A recess shown in  FIG. 10D  is formed by inwardly extruding a portion having a trapezoidal cross-section from a cover material. The recesses of the various cross-sectional shapes shown in  FIGS. 10A to 10D  in the outer rear surface portion  603  of the rear cover  602 , like the recesses of the shapes shown in  FIGS. 10A to 10D , can prevent chips and cutting fluid from getting into the turret mechanism portion  604 . 
         [0050]    In the embodiments and modifications described above, the projections or recesses that define the cutting fluid passages are provided in the upper part of or in the upper part and the left and right side portions of the outer rear surface portion  603  of the rear cover  602 . However, in a case where another member is provided in the upper part of the outer rear surface portion  603 , for example, chips and cutting fluid can be prevented from getting into the turret mechanism portion  604  by simply providing projections or recesses for passages at only the left and right side portions of the outer rear surface portion  603 . 
         [0051]    In above-described embodiments and modifications, moreover, only the projections or recesses are used as members that define flow passages. Alternatively, however, projections and recesses may be used in a mixed manner.