METHOD OF PREPARING NC DATA

Abstract: The rotational direction of a main shaft is stored in a tool data file memory (101b) for each tool. Data necessary for pre­ paring an NC program are stored in an RAM (105) inter­ actively using an operation board (108) or a graphic display device (102). Thereafter, a processor (103) prepares the NC program using the data stored in the RAM. When a tool to be used for a predetermined machining step is determined in preparing the NC program, a tool select instruction for selec­ ting the tool and the rotational direction of the main shaft that fits to the selected tool are found from the tool data file memory (101b), and a main shaft rotation instruction is prod­ uced to turn the main shaft in said direction.

Description: This invention relates to a method of preparing NC data and, more particularly, to an NC data preparation method in which the rotating direction of a spindle is stored for each and every tool used and a spindle rotating direction command is outputted together with a tool selection instruction. As disclosed in the specification of U.S.P. 4,490,781, automatic programming systems are available for creating NC tapes (NC data) from a design drawing through a simple operation by entering data in a conversational mode using a graphic display screen. With such an automatic programming system, the necessary data are created sequentially in accordance with the following steps: (1) a step of inputting the material of a blank; (2) a step of inputting the format of the drawing; (3) a step of inputting the blank profile (chosen from among a cylinder, hollow cylinder and special profile blank) and profile dimensions; (4) a step of inputting the finished profile and finished profile dimensions; (5) a step of inputting a machine reference point and turret position; (6) a step of deciding a machining process; (7) a step of deciding a tool; and (8) a step of deciding cutting limits and cutting conditions. The steps (6) through (8) are repeated until the final finished profile is obtained. The machining processes, the tools used in these machining processes, the cutting conditions and the cutting limits are decided automatically. For example, the following is registered in memory beforehand as a sequence of machining processes for machining a cylinder: (1) end face rough cutting; (2) outer diameter rough cutting; (3) end face finishing; (4) outer diameter finishing; (5) grooving; and (6) thread cutting. Further, for each and every tool, a tool data file is registered which includes the name of the machining process in which the tool is used and tool shape data indicative of the tool. When the cylinder is inputted as the shape of the blank and the finished profile is then inputted, the names of the machining processes are read out in the order in which the machining processes were registered and tools which will not interfere with the workpiece are selected, upon considering the finished profile and the shapes of the tools, from among the tools registered for the machining processes that have been read. In addition, a machining area is decided based on the blank profile and finished profile, and a direction for approaching the chuck (along the -X or -Z axis) is decided as the cutting direction. When the inputting of all data necessary for creating NC data is completed by the foregoing steps, the NC data (an NC tape) are finally created in automatic fashion. As for automatically deciding the machining processes, see the specifications of EP-A-166 783 and EP-A-198 927 both forming state of the art under Art. 54(3) EPC. With regard to automatically deciding tools used, see the specification of EP-A-165 999, forming state of the art under Art. 54(3) EPC. In the prior art, spindle rotating direction is treated as being dependent upon the machining process and is stored beforehand in a parameter storage area. With each new machining process, the rotating direction is determined upon referring to the parameter storage area. The NC data are created upon outputting a spindle rotation command (M03 for forward rotation and M04 for reverse rotation) together with a tool selection instruction. More specifically, a corresponding relationship between the machining process and spindle rotating direction (i.e. forward rotation for end face cutting, reverse rotation for outer diameter cutting, and so forth) is stored as a parameter in the parameter storage area in advance and the NC data are created upon determining the spindle rotating direction based on the corresponding relationship. However, there are right-handed tools and left-handed tools, in which case the spindle rotating direction is fixed at either forward rotation or reverse rotation. If left- and right-handed tools are used, a workpiece cannot be machined unless the spindle is rotated in the direction decided by the particular tool. With the prior-art method, however, the direction in which a spindle is rotated is decided in dependence upon the machining process without taking the left- and right-handedness of the tools into account. As a result, left- and right-handed tools cannot be used. If they were used, this would necessitate the subsequent revision of the NC data that have been created. Accordingly, it is desirable to provide an NC data creation method through which the direction in which a spindle is rotated can be decided in dependence upon the tool. EP-A-0 145 934 discloses a tool display method in which a memory of an NC unit stores tool data including a tool mounting direction for each of a plurality of tools. The tool mounting direction indicates left- or right-handedness of the tools and is used in determining a tool display configuration for showing on a display. FR-A-2 515 378 discloses a tool selection process used in a machining centre, in which tool combination lines are stored in a memory which identify tools to be used for particular types of machining. Machining is divided into "machining units" comprising various respective kinds of point, line and surface machining. EP-A-0 177 164 is prior art for the present application only under Article 54(3) EPC. This document discloses a method for creating NC programs which uses a tool data file providing tool specifications including a required direction of rotation. According to the present invention, there is provided an NC data preparation method in which NC data is prepared by previously registering tools in a tool data file which includes names of machining processes in which said tools are used as well as tool shape data indicative of said tools, and, when machining processes necessary for obtaining a finished shape have been decided, selecting tools to be used in said machining processes from among the registered tools, said method characterised by:- including in said tool data file information on a spindle rotating direction for each tool; presetting by a parameter whether a spindle rotating direction is decided in dependence upon a machining process or in dependence upon a tool to be used; checking said parameter to distinguish between machining-process-dependence and tool-dependence when a tool is selected; obtaining the spindle rotating direction of the selected tool from said tool data file in a case where the spindle rotating direction is tool-dependent; and outputting a tool selection command designating the selected tool, together with a spindle rotating command for rotating the spindle in said obtained direction. In a preferred embodiment, the method further comprises storing a correspondence table indicating correspondence between machining processes and spindle rotating directions, and in a case where a spindle rotating direction is found to be machining-process-dependent by said check of said parameter, the spindle rotating direction of said machining process is obtained from the correspondence table. Thus, in the present invention, the rotating direction of a spindle is stored in a tool data file storage area for each and every tool used, but it is still possible to decide the spindle rotating direction in dependence on the machining process. Data necessary for creating an NC program are stored in a RAM conversationally using an operator's panel and graphic display unit. Thereafter, a processor creates the NC program using the data stored in the RAM. When a tool used in a predetermined machining process is chosen during the creation of the NC program, a tool selection command for selecting the tool is outputted and, in addition thereto, a spindle rotating direction conforming to the selected tool can be obtained from the tool data file storage area and a spindle rotating command for rotating the spindle in said direction is outputted. Reference is made, by way of example, to the accompanying drawings, in which:- Fig. 1 is a block diagram of an automatic programming system; Fig. 2 is a view for describing tool shapes; Fig. 3 is a view for describing a method of mounting a tool on a turret; and Fig. 4 is a flowchart of processing embodying the invention. Referring to Fig. 1, numeral 101 denotes a non-volatile memory having a storage area 101a in which a machining process sequence corresponding to each blank profile (cylinder, hollow cylinder and special profile) is stored in advance, a storage area 101b in which a tool data file (tooling file) is stored in advance, a storage area 101c in which a material file is stored in advance, and a storage area 101d in which parameters are stored in advance. An example of a machining process sequence for a case where the profile is a cylinder is as follows: (1) end face rough cutting; (2) outer diameter rough cutting; (3) end face finishing; (4) outer diameter finishing; (5) grooving; and (6) threading. The tool data file includes the following for each and every tool: (a) the name of a machining process in which the tool is used; (b) tool shape data; (c) data for mounting the tool on a turret; and (d) data indicative of spindle rotating direction for when the tool is used. Fig. 2 is a view for describing tool shape data. RN denotes tool nose radius, AC cutter angle, AN nose angle, XN, ZN imaginary nose positions, and WN nose width (inclusive of grooving cutting tool). The positive direction of the cutter angle AC is counter-clockwise with a main cutter (the solid line in the drawing) serving as a reference, and the positive direction of the tool angle AN is clockwise with the main cutter serving as a reference. Fig. 3 is a view for describing the mounting of a tool TL on a turret. The direction of the cutter and where the cutter is attached are inputted by being expressed in terms of a mounting angle AS and mounting position ZS, XS. The positive direction of the mounting angle AS is counter-clockwise. Various parameters are stored in the parameter storage area 101d. The parameters related to the invention are as follows: (a) a parameter P A indicating the correspondence between each machining process and spindle rotating direction, and (b) a parameter P B indicating whether spindle rotating direction is decided in dependence upon the tool or, as in the prior art, in dependence upon the machining process. Numeral 102 designates a graphic display unit, 103 a processor, 104 a ROM storing a control program, 105 a RAM for storing entered data, the results of processing and created NC data, 106 an NC data output unit for delivering created NC data to an external memory medium 107 such a paper tape or bubble cassette. Numeral 108 denotes an operator's panel. Overall processing according to the invention will now be described in accordance with the flowchart shown in Fig. 4. (a) As in the conventional method, the blank material, format of the design drawing, profile and dimensional values of the blank, finished profile and its dimensions, part profile (finished profile) and its dimensions, machine reference point and turret index position are inputted by the operator's panel 108 and stored in the RAM 105. (b) The processor 103 checks whether the prevailing state is that for machining sequence determination. If this is the case, the machining processes, the tools used in the machining process, the cutting areas and the cutting directions are automatically decided. The criterion for tool selection is that a selected tool not interfere with the workpiece, as indicated in U.S.P. 4,445,182. (c) When entry of all data necessary for NC data creation is completed by the foregoing steps, NC data (NC tapes) are finally created automatically. Specifically, one block of NC data are created sequentially, the NC data are checked to determine if the data are indicative of program end, NC data creation processing is concluded if the data are indicative of program end, and if the data are not indicative of program end, then it is determined whether they form a tool selection instruction (steps 101 through 103). If the NC data do not form a tool selection instruction, then the NC data are outputted (step 104). If the NC data do form a tool selection instruction, then, before the tool selection instruction is outputted, the parameter P B is referred to in order to determine whether the spindle rotating direction is dependent upon the machining process or the tool (step 105). If the spindle rotating direction is machining process-dependent, then, as in the prior art, the parameter P A is referred to in order to obtain a spindle rotating direction for the machining process using the selected tool (step 106), and an M-function instruction (M03 for forward and M04 for reverse) for rotating the spindle in said rotating direction is outputted after the tool selection instruction (T □□□□ ) (steps 107, 108). If the spindle rotating direction is tool-dependent, however, the tool data file of the tool selected by the tool selection instruction is referred to in order to obtain the spindle rotating direction of the tool (step 109), and an M-function instruction (M03 for forward and M04 for reverse) for rotating the spindle in said rotating direction is outputted after the tool selection instruction (T □□□□ ). Thus, in the present invention, the arrangement is such that a spindle rotating direction for each and every tool used is stored in a tool data file and, when NC data are created, a tool selection instruction for selecting a predetermined tool and a spindle rotating command for rotating the spindle in a direction commensurate with the tool are outputted. As a result, the rotating direction of a spindle can be decided in dependence upon the tool, so that the correct spindle rotating direction can be decided even if right- and left-handed tools are used.

Claims: An NC data preparation method in which NC data is prepared by previously registering tools in a tool data file (101b) which includes names of machining processes in which said tools are used as well as tool shape data indicative of said tools, and, when machining processes necessary for obtaining a finished shape have been decided, selecting tools to be used in said machining processes from among the registered tools, said method characterised by:- including in said tool data file (101b) information on a spindle rotating direction for each tool; presetting by a parameter (P B ) whether a spindle rotating direction is decided in dependence upon a machining process or in dependence upon a tool to be used; checking said parameter (P B ) to distinguish between machining-process-dependence and tool-dependence when a tool is selected; obtaining the spindle rotating direction of the selected tool from said tool data file (101b) in a case where the spindle rotating direction is tool-dependent; and outputting a tool selection command designating the selected tool, together with a spindle rotating command for rotating the spindle in said obtained direction. A method according to claim 1, further comprising:- storing a correspondence table indicating correspondence between machining processes and spindle rotating directions; and in a case where a spindle rotating direction is found to be machining-process-dependent by said check of said parameter (P B ), obtaining the spindle rotating direction of said machining process from said correspondence table. A method according to claim 1, further comprising:- presetting by a further parameter (P A ) a spindle rotating direction associated with each machining process; and obtaining the spindle rotating direction from said further parameter (P A ) in a case where the spindle rotating direction is found to be machining-process-dependent by said check of said first-mentioned parameter (P B ).

Inventors: KAWAMURA, HIDEAKI, MATSUMURA, TERUYUKI, MINESHIGE, TAKAHIKO
Applicants: FANUC LTD.
Application year: 1986
Main classification: B23Q15
IPC codes: B23Q15, G05B19