Abstract:
In an automatic chuck jaw change system, a combined machining lathe capable of positioning with high precision and a robot with lower positioning precision than the combined machining lathe cooperate to automatically change a chuck jaw. The system includes a robot disposed in front of the combined machining lathe, and the robot can be selectively mounted on a front end of an arm thereof with a work hand for operating a work, a chuck jaw, and a nut runner hand for operating a drive mechanism of the chuck. The robot cooperates with a tool for jaw mounted on a tool spindle of the combined machining lathe to automatically change a chuck jaw of a main spindle.

Description:
The present application is based on and claims priority of Japanese patent application No. 2007-308581 filed on Nov. 29, 2007, the entire contents of which are hereby incorporated by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an automatic chuck jaw change system in a combined machining lathe. 
   2. Description of the Related Art 
   A combined machining lathe, capable of machining various types of works, requires a chuck jaw compatible with the shape and structure of each of the works. 
   The following patent documents disclose a system or an apparatus for changing a chuck jaw in a combined machining lathe: Japanese Patent Application Laid-Open No. 6-190616, Japanese Patent Application Laid-Open No. 6-143014 and Japanese Patent Application Laid-Open No. 61-103746. 
   For unattended automatic operation of a combined machining lathe over a long time, the combined machining lathe needs to be equipped with a robot for carrying a work in/out of the combined machining lathe. 
   A robot for carrying a work in/out has lower positioning accuracy of an arm front end than mechanical positioning accuracy of each device of a combined machining lathe. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to provide a system in which a tool spindle of a combined machining lathe and a robot cooperate to change a chuck jaw of a main spindle. 
   In view of the above circumstances, a system according to the present invention includes, as basic means, a combined machining lathe including a main spindle, having a chuck for gripping a work, and a tool spindle which moves along a Z-axis parallel to the axis of the main spindle, an X-axis orthogonal to the axis of the main spindle and a Y-axis perpendicular to a plane formed by the Z-axis and the X-axis and rotates around a B-axis as a rotational axis perpendicular to the plane formed by the Z-axis and the X-axis; and a robot disposed in front of the combined machining lathe, wherein the robot has a nut runner hand and a jaw hand selectively mounted on the front end of an arm thereof, and the combined machining lathe and the robot cooperate to automatically change a jaw of the chuck. 
   Moreover, the nut runner hand may have a nut runner for operating a cam bolt engaging and disengaging a chuck jaw drive mechanism and the jaw, and the jaw hand may have a gripper for gripping the jaw. 
   The tool spindle may be selectively provided with a jaw tool for operating the chuck jaw and an air blow tool for air blowing, in addition to various types of machining tools. 
   The jaw tool may come into point contact with the jaw. 
   The chuck may be rotated to a position at which a chuck groove is directed in the horizontal direction, in removing the jaw from the chuck of the main spindle. 
   The automatic chuck jaw change system may further include a process of air-blow to clean a chuck groove from which the jaw is removed and the removed jaw. 
   The automatic chuck jaw change system may further include a jaw stocker provided in an operating area of the robot. 
   In an automatic chuck jaw change system of the present invention, a chuck and a tool spindle of a combined machining lathe capable of high accuracy indexing and positioning and a robot can cooperate to automatically change a chuck jaw of a main spindle. During tool change, cleaning of a removed jaw and a chuck groove can also be automatically performed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a top view illustrating the whole configuration of a system according to the present invention; 
       FIG. 2  is an illustrative diagram of a principal part of a combined machining lathe; 
       FIG. 3  is an illustrative diagram of a process of automatic change of chuck jaws; 
       FIG. 4  is an illustrative diagram of a process of automatic change of chuck jaws; 
       FIG. 5  is an illustrative diagram of a process of automatic change of chuck jaws; 
       FIG. 6  is an illustrative diagram of a process of automatic change of chuck jaws; 
       FIG. 7  is an illustrative diagram of a process of automatic change of chuck jaws; 
       FIG. 8  is an illustrative diagram of a process of automatic change of chuck jaws; and 
       FIG. 9  is an illustrative diagram of a process of automatic change of chuck jaws. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  is a top view illustrating the whole configuration of an automatic chuck jaw change system in a combined machining lathe according to an embodiment of the present invention. 
   This system includes a robot  50  having an articulated structure provided in front of a combined machining lathe  10 . 
   The robot  50  includes a main body  51  and an arm  52  extending from the main body  51 . On the front end of the arm  52 , there are selectively attached a work hand  60  for gripping a work, a jaw hand  70  for gripping a chuck jaw and a nut runner hand  80  for unlocking a chuck mounted on a main spindle of the combined machining lathe  10 . The respective hands are placed on the respective stands. 
   On the side of the combined machining lathe  10 , a work supply station  90  and a pallet conveying apparatus  100  conveying a pallet are provided. 
   A shelf-like jaw stocker  110  is also placed. 
   The robot  50  operates within an area shown by a reference symbol E 1  in  FIG. 1  and an operation panel  120  for an operator is placed outside the area E 1 . 
     FIG. 2  is an illustrative diagram of a principal part of the combined machining lathe  10 . 
   A main spindle  12  of the combined machining lathe  10  is attached with a chuck  20 . The chuck  20 , having three jaws, is a so-called “three-jaw chuck”. A jaw  40  is provided for each of the three chuck grooves  22 . Each of the jaws  40  includes a soft jaw  44  and a master jaw  41  to which the soft jaw  44  is secured by a bolt  46 . The master jaw  41  has a rack  42  engaging with a drive mechanism of the chuck  20 . 
   A tool T 1  for jaws is processed so that a portion  35  in contact with the jaw  40  is formed into a spherical shape. 
   A tool spindle  30  disposed at a position opposed to the main spindle  12  moves in Z-axis direction parallel to the axial line of the main spindle  12  and in the X-axis direction orthogonal to the Z-axis. The tool spindle  30  can also move along Y-axis (not shown) perpendicular to a plane formed by X-axis and Z-axis. 
   Further, the tool spindle  30  can rotate around B-axis that is a rotational axis parallel to Y-axis. 
   The tool spindle  30  can be replaceably mounted with various types of tools supplied from the automatic tool change system. The tool T 1  for jaw automatically changes the jaw  40  for the chuck  20  in cooperation with a robot, which will be described below. 
     FIGS. 3 to 9  illustrate a series of processes of automatic change of a chuck jaw. 
     FIG. 3(   a ) illustrates a process of cleaning a work gripping surface of the chuck jaw  40  with air-blowing tool A 1  mounted on the tool spindle  30 , prior to chuck jaw change. During this process, the robot is kept in a standby state. 
     FIG. 3(   b ) illustrates that the main spindle attached with the chuck  20  is rotated in the C 1  direction around a rotational axis so that the jaw  40  to be changed comes in a horizontal position. 
   The tool mounted on the tool spindle  30  is changed with the tool T 1  for jaw. The robot is kept in standby state. 
     FIG. 3(   c ) illustrates a process of inserting a nut runner  82  into a cam bolt of the chuck  20  and rotating the cam bolt by 180 degrees with the nut runner hand  80  attached to the front end of the robot arm. By this operation, a rack of the jaw  40  is released from the drive mechanism of the chuck  20 . 
     FIG. 3(   d ) illustrates a process in which the nut runner hand  80  keeps the position and the tool spindle  30  moves in the horizontal direction so that the tool T 1  for jaw pushes the jaw  40  out to a predetermined external position. 
   As illustrated in  FIG. 2 , the portion  35  of the tool T 1  for jaw is in point contact with the jaw  40  so that generation of twisting in pushing a jaw  40  out is inhibited. 
     FIG. 4  illustrates a process of taking the jaw  40  out in cooperation of the tool spindle  30  and the robot. 
   The robot changes the hand on the arm front end from the nut runner hand  80  to the jaw hand  70 , grips the jaw  40  with a gripper  72  of the jaw hand  70  and removes the jaw  40  from the chuck  20  in cooperation with the tool T 1  for jaw of the tool spindle  30 . 
   The rotation angle of the chuck  20  and movement of the tool spindle mounted with the tool T 1  for jaw are controlled with high precision by a NC device of the combined machining lathes, thus the jaw  40  is securely removed from the chuck groove  22  of the chuck  20 . 
     FIG. 5  illustrates a process of rotating a robot hand to direct the jaw  40  gripped by the gripper  72  of the jaw hand  70  upward and cleaning the jaw  40  with the air-blowing tool A 1  mounted onto the tool spindle  30 . 
   Cutting chips attaching to the jaw  40  are completely cleaned so as not to be left on the rack  42  and the jaw  40  is returned to the jaw stocker  110 . 
     FIG. 6  illustrates a process of returning the jaw  40  to the jaw stocker  110  with the jaw hand  70  by rotating the arm  52  of the robot  50 . 
     FIG. 7  illustrates a process of cleaning the chuck groove  22  with the air-blowing tool A 1  of the tool spindle  30 . 
   At this time, it is preferable to rotate the chuck  20  so that the chuck groove  22  of the chuck  20  is directed downward from the center of the chuck  20 . 
     FIG. 8(   a ) illustrates a process of taking a new jaw  40  from the jaw stocker  110  with the jaw hand  70  mounted on the arm  52  of the robot  50 . 
     FIG. 8(   b ) illustrates a process of inserting the new jaw  40  into the chuck groove  22  of the chuck  20  with the jaw hand  70 . 
   The insertion amount is, for example, 20 mm. This operation is performed solely by the jaw hand  70  and the tool T 1  for jaw of the tool spindle  30  is made on standby. 
     FIG. 8(   c ) illustrates a process of receiving the jaw  40  inserted by the jaw hand  70  with a tool for jaw of the tool spindle  30 . 
     FIG. 8(   d ) illustrates a process of replacing the hand of the robot arm front end with the nut runner hand  80 , engaging the nut runner  82  with the cam bolt of the chuck  20  and rotating the cam bolt by 180 degrees. 
     FIG. 9(   a ) illustrates a process in which the nut runner  82  of the nut runner hand  80  keeps the rotational position and the tool T 1  for jaw of the tool spindle  30  inserts the jaw  40  up to a predetermined position of the chuck groove of the chuck  20 . 
   The portion  35  of the tool T 1  for jaw is in a point contact with the jaw  40  so that generation of twisting in inserting the jaw  40  is inhibited. 
     FIG. 9(   b ) illustrates a process of rotating the nut runner  82  of the nut runner hand  80  in the opposite direction by 180 degrees in a state in which the jaw  40  is inserted by the tool for jaw of the tool spindle  30 . 
   This operation allows the rack of the jaw  40  to engage with the drive mechanism of the chuck  20 . 
   A series of processes described above are repeated to automatically change three jaws  40  of the chuck  20 .