Abstract:
The present invention provides a graphic display device which displays the path of travel of a tool (the locus of the tool) commanded by a numerical control (NC) machining program and is designed to facilitate easy confirmation of the contents of the NC machining program on which each path of travel of the tool is based. To this end, according to the present invention, each travel command block is prestored corresponding to the starting point of each tool locus prepared by interpreting the travel command block, and a cursor is moved along the tool locus by the application of a cursor move command, and when the cursor passes across the starting point of each tool locus, the travel command block corresponding to the starting point is displayed on a display screen.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a graphic display device and, more particularly, to a graphic display device which displays the contents of a numerical control (NC) machining program as the locus of a tool. 
     Conventional display devices of this kind are equipped with functions of displaying an NC machining program as well as a tool locus, but these displays are provided independently of each other, and hence do not bear a clear correspondence therebetween. Because of this, finding an error at a certain place along the tool locus being displayed and correcting the corresponding part (block) of the NC machining program is not easy because it is not easy to pick up or determine the associated block from the NC machining program; this is all the more difficult in the case where the tool locus is partly displayed on an enlarged scale. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to move a cursor along the tool locus being displayed on a screen and to display thereon, together with the tool locus, the NC machining program block corresponding to the locus at the position of the cursor, allowing ease in confirming the contents of an NC machining program on which the tool locus is based. An NC machining program is input into graphic form generating means, where it is interpreted and a series of graphic data necessary for displaying a tool locus are prepared. The graphic data thus produced are each stored in graphic data storage means, the contents of which are provided to a display unit for displaying the tool locus on a screen. Further, an NC machining program block for each graphic form is stored in a program storage means in correspondence to the starting point of the graphic form indicated by each graphic data. Upon application of a cursor move command, cursor control means refers to the contents of the graphic data storage means and moves a cursor along the tool locus being displayed. Program display control means detects whether the cursor has passed through the starting point stored in the program storage means and, if so, reads out of the program storage means the NC machining program block stored therein corresponding to the starting point, for display on the screen of the display unit 3. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a diagram of the functional arrangement of the graphic display device of the present invention; 
     FIG. 2 is a block diagram illustrating the principal part of an example of the hardware structure of the graphic display device of the present invention. 
     FIG. 3 is a flowchart illustrating an example of the software structure of the graphic display device of the present invention; and 
     FIGS. 4(A) and 4(B) are schematic diagrams showing examples of displays. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a diagram of the arrangement of the graphic display device of the present invention. In FIG. 1, an NC machining program is input into graphic form generating means 1, where it is interpreted and a series of graphic data necessary for displaying a tool locus are produced. The graphic data thus produced are stored in graphic data storage means 2 and the contents thereof are provided to a display unit 3 for displaying the tool locus on a screen. An NC machining program block for each graphic form is stored in program storage means 4 with respect to the starting point of the graphic form indicated by the graphic data. Upon application of a cursor move command, cursor control means 5, with reference to the contents of the graphic data storage means 2, and moves a cursor along the tool locus being displayed. Program display control means 6 detects whether the cursor has passed through the starting point stored in the program storage means 4 and, if so, reads out of the program storage means 4 the NC machining program block stored therein corresponding to the starting point, for display on the screen of the display unit 3. 
     In FIG. 2, which illustrates the hardware structure of the present invention, a program memory 20 for storing an NC machining program made up of a series of NC machining program blocks and a work RAM 22 for temporary data processing by a microcomputer 21 are connected to a data bus 23 and an address bus 24 of the microcomputer 21, and they are both accessible by the microcomputer 21. Known programs for implementing a graphic form generating function, a cursor control function and a program display function are stored in a memory of the microcomputer 21. A graphic memory 25 is a writable/readable memory which has storage areas corresponding to the display screen and has its data input terminal connected to the data bus 23 via a data driver 26 and its address input terminal connected to the address bus 24 and a CRT controller 28 via a multiplexer 27, respectively. The output of the graphic memory is input via a parallel-serial converter 29 to a CRT device not shown. The CRT controller 28 generates an address for scanning the graphic memory 25 and horizontal and vertical synchronizing signals for synchronization of the display. An address from the microcomputer 21 and the scanning address are multiplexed by the multiplexer 27. A cursor move button 30 is a button which is used for moving a cursor along a graphic form being displayed, and its state can be read by the microcomputer 21 via a data driver 31. 
     FIG. 3 is a flowchart showing an example of the software arrangement of the graphic display device of the present invention. A description will be given, with reference to this flowchart, of the operation of the device illustrated in FIG. 2. 
     In a mode of displaying a tool locus, the microcomputer 21 first reads out the NC machining program from the program memory 20 block by block (step S1) and prepares, by a known method, graphic data (using a graphic form generating format) following the contents of each NC machining program block (step S3). For example, when the content indicated by a certain block is a command for movement from a point P1 to a point P2, data necessary for displaying a straight line l1 from the point P1 to the point P2 is prepared. The graphic data thus prepared is stored in the work RAM 22 (step S4). 
     Further, the microcomputer 21 stores, corresponding to the starting point of the graphic form represented by the graphic data thus prepared, into the work RAM 22 the NC machining program block related to the graphic data (step S5). In the case of the example, a move command along the straight line l1 from the point P1 is stored in RAM 22. 
     Next, the microcomputer 21 writes data into the graphic memory 25 on the basis of the graphic data prepared as described above, generating the graphic form (step S6). The processes of steps S1 to S6 are repeatedly performed until the NC machining program is finished (step S2). After this, the contents of the graphic memory 25 are cyclically read out by the scanning address from the CRT controller 28 and provided to the CRT device, displaying the tool locus path on the display screen. 
     Upon completion of the above-described processing for the NC machining program, the microcomputer 21 detects whether the cursor move button 30 is being pressed or not (step S7) and, if so, refers to the graphic data stored in the work RAM 22 and moves the cursor along the tool path being displayed, at a predetermined speed (step S8). Simultaneously with the cursor movement, the machine position on the tool locus indicated by the cursor is obtained and displayed on the display screen (step S9). Such a cursor movement as described above can be accomplished, for instance, by moving the cursor, instead of producing the graphic form, in the same sequence as the preparation of the graphic form. That is, upon application of an input for the cursor movement, software proceeds to the routine for preparing the graphic form of the tool locus. Then software performs interpolation in the same manner as in the case of preparing the graphic form and, every moment, it displays the resulting values of X and Y (the machine position) and decides whether the position being displayed is the starting point of each segment. In this case, however, the cursor is moved to the position (X,Y) obtained by the interpolation instead of writing the results in the RAM. 
     During the cursor movement the microcomputer 21 decides whether the cursor has passed a machining block starting point stored in the work RAM 22 (step S10) and, when the cursor moves across each starting point, reads out the NC machining program block stored in the work RAM 22 corresponding to the starting point and displays it on the display screen (step S11). For example, in the case where the tool locus is expressed by straight lines l1, l3 and l4 and a circular arc l2 as shown in FIG. 4(A) when the cursor 35 lies on the straight line l1, and NC machining program block N12G01X . . . Z . . . related to the straight line l1 and the machine position X . . . Z . . . of the cursor 35 are displayed, and when the cursor 35 moves across the starting point P of the curve l2 as shown in FIG. 4(B), an NC machining program block N13G03X . . . Z . . . related to the curve l2 is displayed along with the machine position X . . . Z . . . of the cursor. Incidentally, such a character display can also be provided through the use of the graphic memory 24 but, in general, it is carried out by the employment of a character memory (not shown). 
     While in the above embodiment the machine position is displayed along with the program, it is also possible to adopt such an arrangement in which the display of the former is omitted. 
     According to the present invention, an NC machining program block, which is associated with each graphic form represented by graphic data prepared, is prestored corresponding to the starting point of the graphic form, a cursor is moved, by the application of a cursor move command, along a tool locus and the contents of the NC machining program block corresponding to the graphic form at the position of the cursor are displayed. This gives a clear display of the relationship between the tool locus and the NC machining program and makes it possible to find out the place of the NC machining program that needs to be corrected, allowing ease in correction of the program. Especially, in the case of an enlarged display, the position of the part being displayed, relative to the entire tool locus, is unclear and it is difficult to identify which cutting region is being displayed, making it very difficult to extract the corresponding NC machining program block, but the present invention solves such a problem because the respective portion of the NC machining program is displayed, along with the tool locus.