Abstract:
A tool handling device for a machine tool with a support construction movable along at least two coordinate axes by means of a motor and a gripper arrangement mounted to the support construction. The grippers have two gripper claws pivotable against each other as well as a locking mechanism for fixing the gripper claws in their closed posture. Each gripper has opposed openings for a lateral insertion and extraction of a tool post. Operating elements are provided for pivoting the two gripper claws during the insertion and extraction of a tool post through one of the two openings.

Description:
BACKROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to machine tools, and more specifically to a tool handling device of a machine tool. 
   2. Discussion of Related Art 
   Handling systems are used in connection with tool magazines for machine tools, particularly milling and drilling machines as well as work centers. Various tools may be used. Even though direct tool exchange in the respective work spindle of the machine tool is possible with there handling systems, for example, in accordance the pick-up principle, their preferred field of application is the transport of tools from complex tool magazines to a tool changer, and vice versa. 
   In so-called “shelf magazines,” the tools are disposed in shelves arranged above each other in intervals with their tool posts usually formed as so-called “tool cones.” Each shelf contains a plurality of tool accommodations into which the respective tool posts are inserted. In accordance with the work schedule of the machine tool, a tool selected for the subsequent machining operation is approached by the handling system using the shelf position stored in the program. The gripper grips the respective tool post and transports it into a transfer position where the tool post is transferred to a tool changer. If required, the used tool is taken from the tool changer and accommodated in a respective free space in the shelf magazine. 
   For the above operations different handling systems having various gripper arrangements are known. In all those systems, however, the grippers are only designed for a one-sided access to a tool post. In other words, their gripper claws define a lateral opening through which the tool post is inserted into the gripper and extracted from the gripper in the opposite direction. With this one-sided access capability of the gripper, its movements become complicated if complex magazines are used where, for example, the shelf magazines have a plurality of rows. 
   SUMMARY OF THE INVENTION 
   The present invention relates to a tool handling device of a machine tool having a support construction movable in at least two coordinate axes by means of a motor and a gripper arrangement mounted on the support construction. The grippers of the gripper arrangement have two gripping claws pivotable against each other, as well as a latch mechanism for locking the gripping claws in their closed position. 
   It is one object of the invention to provide a tool handling device for machine tools that enables a more universal utilisation and a reduction of the time required for the tool exchange. According to the invention, this object is achieved by the characterising features of the invention claimed in claim  1 . 
   In the tool handling device according to the invention, the gripper has two diametrically opposed openings for a lateral insertion and extraction of a tool post. In this way a tool post, for example a tool cone, may be inserted into the gripper through its one opening from the one side and extracted through the opening on the other side for a transfer to another device. This other device may be, for example, a tool changer or a work spindle. Since the respective tool post has to be securely held in the gripper during the transfer and transport operations, operating elements for pivoting the two gripper claws of the gripper are provided. They preferably automatically pivot the gripper claws into their closed positions during an insertion or extraction of a tool post through one of the two openings. 
   Conveniently, an operating element is allocated to each gripper claw. The operating elements may have at least one drive stopper provided on the gripper that protrudes into the lateral moving path of the tool post. The drive stopper is kinematically coupled to at least one gripper claw for its pivoting movement. The operating element is activated during an insertion movement of a tool post into the gripper, as well as by a sliding contact of the ring-shaped collar on the upper end section of the tool post with the drive stopper of the operating element, and the respective gripper claw is pivoted through its kinematic coupling. The same applies to the extraction of a tool post from the gripper. The operating element is activated and possibly pivoted outwards together with the gripper claw for releasing the tool post by a sliding contact of the ring-shaped collar mentioned above with the drive stopper. 
   The gripper claws may also be pivoted in and out for gripping or releasing a tool post by means of operating elements made up of a drive, for example a pressure cylinder, and at least one sensor for detecting a tool post during its insertion or extraction as well as its presence in the gripper. For controlling such pressure drives conveniently, a machine control is used. 
   A reliable fastening in the gripper, which is effective even in case of the high inertial forces of possibly heavy tools, may be ensured by a locking mechanism. The locking mechanism may have a pressure cylinder with a respective pin for fixing the respective gripper claw in its closed position. It is particularly advantageous when the locking device has additional components preventing a rotation of the tool post, including its possibly heavy tool even during faster transportation movements. In a preferred embodiment, the locking mechanism has elements for preventing a rotation. These elements are formed as pins that engage with the recesses provided in the uppermost collar of common tool posts when the gripper is closed. 
   According to a further preferred embodiment of the invention, the gripper arrangement has two diametrically opposed support bodies disposed vertically and symmetrical to their longitudinal axis. The gripper claws, including the operating elements, are pivotably supported in the support bodies. The locking mechanism is also disposed in the support bodies. The support bodies, which are efficiently fixedly connected to each other by means of an upper support plate, form a rigid housing complex with an inner space sufficiently large to accommodate the standardized tool posts. The housing assembly of the gripper arrangement is preferably mounted on the free end of a support arm pivotable by means of a motor. To maintain the rotational position of the gripped tool post during a pivoting movement of the support arm, so that the tool post can be extracted from a shelf space and transferred to a tool exchanger in the same angular position, differential gears are provided to keep the rotational position of the gripper constant or unchanged during the pivoting movements of the support arm. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     Further particularities and advantages of the invention will become clear from the following description of preferred embodiments, with reference to the drawing, in which: 
       FIG. 1  is a perspective view of a handling device according to one embodiment of the invention together with a single row shelf magazine; 
       FIG. 1A  is an enlarged perspective view of the handling device according to  FIG. 1 ; 
       FIG. 2  is a schematic perspective view of the gripper arrangement of the handling device according to  FIG. 1 ; 
       FIG. 3  is a bottom view of a gripper with opened gripping claws; and 
       FIG. 4  a bottom view of the gripper according to  FIG. 3  with closed gripping claws. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The system shown in  FIG. 1  is designed for an application to work centers as well as program controlled drilling and milling machines. It has shelf magazine  1  which, in this embodiment, has a plurality of semi-circular accommodations  3  open to the front side for tool posts  5 , each containing one tool  4  in four horizontal shelves  2 , respectively. Shelf  1  is designed as a frame construction and has upper and lower rigid guide rails  6  and  7 . In two guide rails  6  and  7 , vertical beam  8  is shiftably guided along a horizontal coordinate axis as indicated by a double arrow by means of drive motor  9 . On the front side of vertical beam  8 , two vertical guide rails  10  are disposed on which slide  11  is guided. Support frame  12  mounted on slide  11  surrounds vertical beam  8  and carries drive motor  14  for the vertical movements along a second coordinate axis in a direction indicated by a double arrow on its rear wall  13 . On the front side of slide  11 , or of support frame  12 , gripper arrangement  15 , which is shown in detail in  FIG. 1A , is mounted It forms a support construction together with vertical beam  13 . Gripper arrangement  15  has a motor  16  mounted axially parallel on vertical slide  11  and pivoting horizontal support arm  17  about its central axis  18 . On the free end of pivotable support arm  17 , gripper  20 , which is described in detail below with reference to  FIG. 2 , is supported so as to be rotatable about vertical axis  19 . 
   Illustrated gripper  20  has two diametrically opposed support bodies  21  and  22  disposed vertically and axially symmetrical and fixedly connected by upper support plate  23 , whereby a stiff and load carrying assembly is formed. On support plate  23 , gear wheel  24  is fixed, which is partly overcast by continuous V-belt (not shown) arranged within the cover of support arm  17 , and wrapped around a further gear wheel mounted in axis  18  at the end of the support arm. Said cog belt drive ensures that the angular position of gripper  20 , as well as the angular orientation of tool post  5  (the tool cone), remain constant during all operations, for example in case of a pivoting movement of support arm  17 . 
   On each support body  21  and  22  a respective cylinder unit  25  and  26  is fixedly mounted which is respectively part of a locking mechanism. Vertically movable piston rod  27  and  28  of the respective cylinder unit  25  and  26  engages with a respective arcuate grove  29  and  30  formed in liftable and lowerable profiled plate  31  and  32  with an end side head. Each profiled plate  31  and  32  is slidably guided on respectively two sliding pins  34  and  35  fixed to the respective support body  21  and  22 . At the tapered ends of each plate, pin  36 ,  37  respectively axially engages with the axial recess in the ring shaped collar of a tool post and, thus, securing the tool cones against a rotation in the gripper (see  FIG. 4 ). 
   Profiled plates  31 ,  32  are connected with gripper claws  38 ,  40  via sliding pins  34 ,  35  so that they are not rotatable. The gripper claws  38 ,  40  are held in support body  21 ,  22  so as to be pivotable about respective vertical swivel pin  39 ,  41 . Each gripper claw  38 ,  40  is provided with ring segment shaped fixing element  44 ,  45  at its lower end portion. This ring segment shaped fixing element  44 ,  45  engages with the ring shaped grove of a tool cone in the closed state. On ring segment shaped fixing elements  44 ,  45 , ring segment shaped operating elements  42 ,  43 , which are provided with crowned or arcuate stopper edge  47 ,  48  on their end portion, are integrally formed. 
   As can be seen in  FIG. 3 , gripper claws  38 ,  40 , or the ring segment shaped fixing elements attached to their bottom side, define two diametrically opposed openings  50 ,  51 . The width of these openings, indicated by arrows, is greater than the diameter of a conventionally formed cone shaped tool post in the area of its broader ring shaped collar end portion. During the insertion of a tool post through opening  51  into gripper  20 , shown in its open position in  FIG. 3 , the ring shaped collar at the end of cone shaped tool post  5  contacts crowned surfaces  47 ,  48  of two operating elements  42 ,  43  in the position indicated by a dot-chain line. In case of a further insertion of tool post  5  in the direction of the arrow in  FIG. 3 , two operating elements  42 ,  43  are respectively pivoted to the outside about swivel pins  39 ,  41  together with their gripper claws  38 ,  40 . With said pivoting movement, the lower parts of gripper claws  38 ,  40  in  FIG. 3  are moved radially inward. A further insertion movement of the ring shaped collar of the tool post into the gripping posture defined by vertical axis  19  causes gripper claws  38 ,  40  to be pivoted further inward until the closed posture shown in  FIG. 4  is reached. A corresponding effect is obtained if the tool post is inserted through upper opening  50  in  FIG. 3 , since in this case as well the upper cone shaped end of the ring shaped collar moves into a sliding pressure contact to two arcuate surfaces  47 ,  48 . Therefore, operating elements  42 ,  43  are pivoted about swivel pins  39 ,  41  together with gripper claws  38 ,  40 . 
   In the closed position shown in  FIG. 4 , two gripper claws  38 ,  40  are secured against an arbitrary opening in the following way. As can be seen in  FIG. 2 , a respective further plate element  55 ,  56  extending as a prolongation of accommodation slits  29 ,  30  and comprising respective recess  57 ,  58  having a circularly widened end portion is disposed above two profiled plates  31 ,  32 . Plate elements  55 ,  56  follow the pivoting movements of gripper claws  38 ,  40  so that rods  27 ,  28  of cylinder units  25 ,  26  are moved up to the circular end parts of said recesses  57 ,  58 , into a pressure contact with ring shaped collar  59 ,  60  respectively provided on piston rod  27 ,  28  during their closing movement. 
   By supplying pressure oil to cylinder units  25 ,  26 , piston rods  27 ,  28  are extended downwards, and respective profiled plate  31 ,  32  is pushed downwards by the positive engagement of the widened piston head. This results in an extension of pins  36 ,  37  engaging with the recess provided in the respective ring shaped collar of tool post  5 , thereby securing the tool post against a rotation as indicated in  FIG. 4 . 
   The invention is not limited to the illustrated embodiment. For example, other suitable means may be used instead of the mechanical operation of gripper claws  38 ,  40  carried out with the aid of operating elements  42 ,  43  and their arcuate surfaces  47 ,  48 . One possibility is, for example, the provision of one or more sensors detecting the presence of a tool post and activating drive elements opening or closing the gripper claws. To open gripper claws  38 ,  40  and to release tool post  5  after the relief of cylinder units  25 ,  26  spring systems may be used, spring  62  being indicated in  FIG. 2  for this purpose.