Abstract:
A control apparatus for controlling a machine tool on the basis of a machining program is provided with: a storage unit which stores an inspection item list for a workpiece, said inspection item list being associated with the machining program; and a display unit which, when the machining program is executed, displays the stored inspection items associated with the machining program.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a U.S. National Stage patent application of International Patent Application No. PCT/JP2013/085218, filed Dec. 27, 2013, which is hereby incorporated by reference in the present disclosure in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a control device for a machine tool which can carry out an inspection of a machined workpiece on the machine tool. 
       BACKGROUND OF THE INVENTION 
       [0003]    In NC machine tools, the machining accuracy may be changed due to wear of tools, thermal deformation of the machine tool by the changing in ambient temperature or the like. Therefore, there is a control device for a machine tool, the control device measuring a predetermined portion of a workpiece, after one or all of machining processes for the workpieces, to determine whether or not the machining process(es) has (have) been carried out within a predetermined machining accuracy. 
         [0004]    For example, Patent Literature 1 describes an NC device which measures a machined workpiece in accordance with a measuring program, storing the measurement data in the NC device and displays the measurement results based on the measurement data. 
       PRIOR ART DOCUMENTS 
     Patent Literature 1: JP-A-H10-207520 
     SUMMARY OF THE INVENTION 
       [0005]    According to the NC device of Patent Literature 1, it is possible to store and display the measurement results. However, the portions of the machined workpiece to be measured and the measuring method are not clearly shown to an operator when measuring the machined workpiece. Therefore, there is a problem accompanied with the NC device of Patent Literature 1 that the operator cannot judge whether or not the appropriate portion is measured by the correct measuring method. 
         [0006]    The invention is directed to solve the problem of the prior art, and the object of the invention is to provide a control device for a machine tool, enabling a machined workpiece to be inspected on the machine tool. 
         [0007]    To achieve the already explained object, according to the present invention, a control device for controlling a machine tool based on a machining program, comprising a storing section for storing an inspection item list for a workpiece corresponding to the machining program, and a displaying section for displaying the inspection items stored in association with the machining program is provided. 
         [0008]    When inspecting a machined workpiece, the invention allows an operator to understand the inspection, i.e., the inspecting method and the portion to be inspected clearly, and therefore facilitates the inspection without omission. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a block diagram showing an example of a control device for a machine tool according to the invention. 
           [0010]      FIG. 2  is an example of machining results displayed on the displaying section of the control device of  FIG. 1 . 
           [0011]      FIG. 3  is an example of inspection item list displayed on the displaying section of the control device of  FIG. 1 . 
           [0012]      FIG. 4  is an example of a measuring guidance displayed on the displaying section of the control device of  FIG. 1 . 
           [0013]      FIG. 5  is an example of inspection results displayed on the displaying section of the control device of  FIG. 1 . 
           [0014]      FIG. 6  is an example of tool data displayed on the displaying section of the control device of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    With reference to the drawings, an embodiment of the invention will be described below. 
         [0016]    In  FIG. 1 , a control device  10  of a machine tool  20  according to an embodiment of the invention can be formed so as to include an NC device of the machine tool  20 , and comprises an input section  12 , a reading and interpreting section  14 , a interpolating section  16 , a servo-control section  18 , a measurement commanding section  22 , a list of measuring item storage section  24 , a displaying section  26  and an acceptance judging section  28 . The input section  12  may comprise a network means e.g., a LAN, a keyboard or a touch panel. The displaying section  26  can be formed by a display attached to an NC device of the machine tool  20 . 
         [0017]    A machining program  30 , an inspection item list  32  and acceptance criteria  34  are input into the input section  12 . The machining program  30  can be generated by using for example a CAM system. The inspection item list  32  and the acceptance criteria  34  may be decided, in consideration of requirements for the workpiece to be machined in accordance with the machining program  30 , by a CAM operator or an operator of the machine tool  20 . 
         [0018]    The machining program  30  input into the input section  12  is output to the reading and interpreting section  14  as shown by an arrow  12   a . The reading and interpreting section  14  reads and interprets the machining program so that operation commands  14   a  are output. The operation commands include the feeding amounts and speeds in the X-, Y- and Z-axis directions. The operation commands  14   a , which have been output by the reading and interpreting section  14 , are sent to the interpolating section  16 . 
         [0019]    The interpolating section  16  interpolates the operation commands  14 , in the X-, Y- and Z-axis directions, via calculation based on an interpolation function, so that position commands (pulse position commands)  16   a  are output to the servo-control section  18  based on the respective X-, Y- and Z-axial feed speeds. Based on the respective X-, Y- and Z-axial position commands  16   a , the servo-control section  18  outputs electric currents  18   a  to X-, Y- and Z-axial servomotors (not shown) of the machine tool  20 , for driving X-, Y- and Z-axes of the machine tool  20  respectively. 
         [0020]    The inspection item list  32  and the acceptance criteria  34  are sent to the inspection item list storing section  24 , as shown by an arrow  12   b , along with the machining program  30 . The inspection item list storing section  24  stores the inspection item list  32  and the acceptance criteria  34  in association with the machining program  30 . The inspection item list  32  includes at least a measuring mode and a measuring method. The measuring mode includes manual, semi-automatic and automatic measurements. The measuring method includes an inner circular surface measurement for measuring the inner diameter of a circular recess, an outer circular surface measurement for measuring the outer diameter of a circular column, a pocket measurement for measuring the lengths of an opening of a rectangular recess in orthogonal two directions, a groove measurement for measuring the width of a groove, a block measurement for measuring the lengths between two pairs of opposite sides of a rectangular boss, a reference surface measurement and a reference point measurement. Alternatively, an operator may input directly the inspection item list via a key board or a touch panel of the input section  12 . 
         [0021]    The inspection item storing section  24  sends, to the measurement commanding section  22 , inspection items relative to the machining program  30  based on the inspection item list  32  received from the input section  12  (arrow  24   a ). The inspection item list storing section  24  further sends the inspection item list to the displaying section  26  as shown by an arrow  24   b , and sends the acceptance criteria  34  to the acceptance judging section  28  as shown by an arrow  24   c.    
         [0022]    The measurement commanding section  22  contains, in advance, measuring programs corresponding to the respective inspection items included in the inspection item list  32 , and measurement guidance corresponding to the respective measuring programs. The measurement commanding section  22  sends a measuring program, corresponding to the inspection item received from the inspection item list storing section  24 , to the reading and interpreting section  14 , as shown by an arrow  22   a , and sends a measurement guidance to the displaying section  26  as shown by an arrow  22   d.    
         [0023]    The acceptance judging section  28  receives measurement results from the machine tool, as shown by an arrow  20   a , to compare it with the acceptance criteria  34  received from the inspection item list storing section  24  whereby it is determined whether or not the machined workpiece is processed within a predetermined machining accuracy. The determination result is sent to the displaying section  26  as shown by an arrow  28   a.    
         [0024]    The operation of the embodiment will be described below. 
         [0025]    When a machining process, according to a machining program, is completed, the machining results are displayed as shown in  FIG. 2 . In the machining result window, shown in  FIG. 2  as an example, a machining results table  36  is displayed along with a drawing  38  relative to the completed machining program. The machining results table  36  may include program number  36   a , the starting time of machining  36   b , the time required for machining  36   c , machining data name  36   d  which indicates a folder containing a computer file such as a text file describing the data in relation to the tools and the workpiece. The drawing  38  may be output to the displaying section  26  from a server via a LAN, the input section  12  and the inspection item list  24 , by using a program number (O 1000  in  FIG. 2 ) of the machining program as an argument. 
         [0026]    Accordingly, displaying the machining results before the inspection of the machined workpiece allows an operator to confirm easily that the machining process completed successfully. In particular, the drawing  38 , relative to the machining program, allows an operator to confirm which machining program was used for the machining. Further, combining the machining results into a computer file as shown in  FIG. 2  facilitates to refer to past machining results. 
         [0027]    When an operator clicks or taps a tab  40  of the machining result window displayed on the displaying section  26 , an inspection item list window, shown in  FIG. 3 , is displayed on the displaying section  26  based on the inspection item list received from the inspection item list storing section  24 . In the inspection item list window of  FIG. 3 , inspection number  42  (in  FIG. 4 , 1-3 are indicated as the inspection number), judgment  44 , of the measurement results, the measuring mode  46  and the measuring method  48  and so on are shown. 
         [0028]    In the example of  FIG. 3 , the inspection number 1 indicates fetching of the coordinate as the measuring method  48  and manual measurement as the measuring mode  46 . In particular, the X-, Y- or Z-feed axes of the machine tool  20  is operated manually so that a measuring probe is moved in one direction along the X-, Y- or Z-axis toward a portion of the machined workpiece to be measured, for example a predetermined apex or a side face whereby the X-, Y- or Z-axis coordinate value is read by a coordinate reading means of the feed device of the machine tool  20 , for example a digital scale (not shown) of the X-, Y- or Z-axis, when the measuring probe touches the predetermined portion. The inspection item list window of  FIG. 3  includes the judgment  44  of the measurement results as described above, in which the machined workpiece is acceptable in relation to the inspection of number 1, but is not acceptable in relation to the inspection of number 3. The inspection of number 2 was not conducted. 
         [0029]    Further, in the inspection item list window of  FIG. 3 , the inspection of number 2 indicates that the inner circular surface measurement, as the measuring method  48 , is conducted by the semi-automatic mode, as the measuring mode  46 . The inner circular surface measurement is a measuring method for measuring the inner diameter of a circular recess as described above, and includes, as the measurement items, the measurement of the X- and Y-coordinates (Z-coordinate may be included if necessary) of the center of the circular recess, and the measurement of the diameter of the recess measured in both the X- and Y-axes directions. Furthermore, in the example of  FIG. 3 , the judgment of the inspection of number 2 is “not yet”, which means that the inspection of this item has not been conducted yet. 
         [0030]    If an operator clicks or taps an inspection start button  50  of the inspection number 2, then a measurement guidance window, illustrating the procedure of the semi-automatic inner circular surface measurement, as shown in  FIG. 4 , is displayed in the displaying section  26 , based on the measurement guidance received from the measurement commanding section  22 . In the measurement guidance of  FIG. 4 , an icon  52  indicates the inner circular surface measurement as the measuring method, and an icon  54  indicates that a measuring probe Pm should be moved to inside the circular recess Rc, as shown by a graphic  56 . When a positioning finish button  58  is clicked or tapped, after an operator confirms visually that the measuring probe Pm has been manually moved inside the circular recess Rc by the operator with X-, Y- and Z-axis handles of the machine tool  20 , the inner circular surface measurement is automatically conducted by the machine tool  20 . Accordingly, when the positioning finish button  58  is clicked or tapped, the measurement commanding section  22  sends the measuring program to the reading and interpreting section  14 . The reading and interpreting section  14  reads and interprets the measuring program to send the operation commands to the interpolating section  16 . The interpolating section  16  sends the position commands to the servo-control section  18 . The servo-control section  18  outputs the drive currents to the X-, Y- and Z-axial servomotors of the machine tool  20 . 
         [0031]    The machine tool  20  drives the X-, Y- and Z-feed axes respectively based on a measuring program. Accordingly, the machine tool  20  calculates the measurement results based on the values of the X-, Y- and Z-axial digital scales when the measuring probe Pm, attached to the end of a spindle, contacts the machined workpiece W. The measurement results are send to the acceptance judging section  28 . The acceptance judging section  28  compares the measurement results, which have been received from the machine tool  20 , with the acceptance criteria, which have been received from the inspection item list storing section  24 . The determination result is displayed on the displaying section  26 . In the example of  FIG. 3 , the determination result is indicated in the judgment  44 . 
         [0032]    A report window, shown in  FIG. 5 , is displayed by clicking or tapping a tab  60 . An inspection results table  62  is shown in the report window along with a machining results table  62 , which is similar to the machining results table  36 , described above. The inspection results table  62  and the machining results table  64 , which are shown in the report window, may be printed as a hard copy or stored in a server or the like as an electronic file. 
         [0033]    Further, a tool data table  72 , shown in  FIG. 6 , containing data relative to all of the tools, which were used for carrying out the machining program, is displayed by clicking or tapping a tab  70  of the inspection item list window of  FIG. 3 . The tool data table  72  shows, in association with tool number  72   a , tool name  72   b , service time  72   c , cutting time  72   d , i.e., the actual time when the tool was used to cut, cutting length  72   e , i.e., the length which the tool actually cut, spindle load  72   f , i.e., the maximum load applied to the spindle to which the tool is attached, and thrust and radial spindle loads  72   g  and  72   h , i.e., the maximum loads applied in the thrust and radial directions to the spindle to which the tool is attached. 
         [0034]    As described above, the embodiment can display the inspection item list window shifted from the machining results window, allowing an operator to measure a machined workpiece in accordance with the inspection item list without hesitation, whereby the operator can execute the inspection without confusing what inspection should be executed. 
         [0035]    The inspection item list may be separately composed or incorporated in a machining program by a programmer. Omission of inspection item can be prevented by incorporating a measuring program into a machining program. In order to incorporate a measuring program into a machining program, ID numbers may be attached to the measuring program portions whereby the measurement results are stored in the control device  10  in association with the ID numbers. 
         [0036]    Further, an interlock may be incorporated into a machining program in order to prevent the next workpiece being machined before the acceptance judging section  28  completes the judgments in relation to all of the inspections described in the inspection item list. 
         [0037]    The data relative to the status of use of the tools which were used for machining is displayed, enabling the tool lives to be estimated. Furthermore, the tool data includes the maximum load applied to the tool or the spindle, enabling to determine whether or not the cutting speed can be increased. Furthermore, the past maximum loads applied to the tools may be stored in the control device  10  whereby machining process can be stopped if a load larger than the maximum load is applied when machining in accordance with the same machining program. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           10  Control Device 
           12  Input Section 
           14  Reading and Interpreting Section 
           16  Interpolating Section 
           18  Servo-Control Section 
           20  Machine Tool 
           22  Measurement Commanding Section 
           24  Inspection Item List Storing Section 
           26  Displaying Section 
           28  Acceptance Judging Section 
           30  Machining Program 
           32  Inspection Item List 
           34  Acceptance Criteria 
           50  Inspection Starting Button 
           64  Machining Results Table