Theory and Design of CNC Systems Part 13 pptx

408 11 STEP-NC System (ABS) Milling_type_operation (ABS)Milling_machine_operation (ABS)Machine_operation (ABS) Drilling_type_operation (ABS) Two5D_milling_operation Freeform operation (ABS) Plane_milling (ABS) Side_milling (ABS) Bottom_and_side_milling (ABS) Drilling Operation (ABS) Boring_operation Back_boring Tapping Thread_drilling 1 1 Part 11 Fig. 11.11 EXPRESS-G diagram for machining operation in Part 11 (ABS) Two5D_milling_strategy (ABS) Freeform_strategy (ABS) Drilling_type_strategy Bidirectional_contour Contour_bidirectional Center_milling Undirectional_milling Bidirectional_milling Contour_parallel Contour_spiral Uv_strategy Plane_cc_strategy Plane_c1_strategy Leading_line_strategy 11 Fig. 11.12 EXPRESS-G diagram for machining strategy in Part 11 11.4.5 Tools for Milling and Turning This section deals with Part 111: “Tools for milling machines” and Part 121: “Tools for turning machines”. Part 111 and Part 121 define data elements describing cutting tool data for milling machine tools and machining centers and for turning machine tools, respectively. In ISO 6983, the tool is defined by its identifier (e.g. T8) and no further informationcon- cerning the tool type or geometry is given. This information is part of the tool setup sheet, which is supplied with the NC-program to the machine. However, ISO 14649 includes this information in the part program, such as tool identifier; tool type; tool geometry; application-dependentexpected tool life. These data elements can be used as criteria to select one of several operations; they do not describe complete informa- tion of a particular tool. Therefore, leaving out optional attributes gives the controller more freedom to select from a larger set of tools. Part 10 defines machining tool as 11.4 STEP-NC Data Model 409 manufacturing_feature transaction_feature two5_manufacturing_feature region replicate_feature turning feature machining_feature compound_feature knurl revolved_feature outer_round straght_knurl diagonal_knurl diamond_knurl catalogue_knurl revolved flat revolved_round groove general_revolution outer_diameter outer_diameter_ to_shoulder 1 1 1 1 1 1 Fig. 11.13 EXPRESS-G diagram for turning feature (ABS)turning_machining_operation (ABS)grooving (ABS)facing facing_rough facing_finish (ABS)contouring contouring_rough contouring_fihish (ABS)threading threading_rough threading_finish grooving_rough grooving_finish cutting_in knurling 1 1 1 1 1 Fig. 11.14 EXPRESS-G diagram for turning machining operation 410 11 STEP-NC System a supertype of milling machine cutting tools and turning machine cutting tools that are defined in Part 111 and Part 121 respectively. Figures 11.15 and 11.16 show the structure of the milling machine cutting tool and turning machine cutting tool elements. (ABS)Machining_tool its_cutting_edge SET[1:?] Cutting_component overall_assembly_length (ABS)Milling_machine_ cutting_tool effective_cutting_diameter length_measure maximum_depth_of_cut hand_of_cut Hand BOOLEAN Rotating_boring_cutting_tool Drilling_cutting_tool Reaming_cutting_tool Tapping_cutting_tool Milling_cutting_tool Twist_drill Counter_sink Counter_bore Spot_drill Step_drill Spade_drill Shoulder_mill T_slot_mill Side_mill Thread_mill End_mill Dovetail_mill Face_mill coolant_through_tool 1 1 Fig. 11.15 EXPRESS-G diagram for milling machine cutting tool 11.5 Part Programming Based on the data model, the STEP-NC part program is represented as a physical file according to ISO 10303 Part 21: Clear Text Encoding Rule. As shown in Fig. 11.18, the STEP-NC part program is divided into the header section and the data section. The header section includes information with regard to the part program itself, such as the author information, schema information and version of the part program. The data section includes all the information about the manufacturing such as process se- quence, manufacturing feature, operation type, machining strategy, machining tech- nology, machine function, workpiece and geometry. In this subsection, STEP-NC part programs for milling and turning will be described. 11.5 Part Programming 411 machining_tool(Part 10) (ABS)turning_machine_ cutting_tool length_measure length_measure length_measure length_measure length_measure 2. 1. cutting_edge_properties length_measure [left, right, neutral] general_turning_tool 3. 2.turning_threading_tool 3. 1.grooving_tool 3. 3.Knurling_tool 3. 4.user_defined_turning_tool 1 functional_length f_dimension minimum_cutting_diameter a_dimension_on_f a_dimension_on_lf cutting_edge hand_of_tool Fig. 11.16 EXPRESS-G diagram for turning machine cutting tool 11.5.1 Part Programming for the Milling Operation Figure 11.17 shows a simple example for milling, described in Annex E of ISO 14649 Part 11. Figure 11.18 shows the overall structure of the STEP-NC part pro- gram for the test part of Fig. 11.17. Note that the part program of Fig. 11.18 is just a fraction of the whole program in order to reduce space. For the full version of this part program, please refer to Annex E of ISO 14649 Part 11. The shape of Fig. 11.17 includes a plane at the top face (planar face), a rect- angular pocket (closed pocket) and a hole (round hole). In this section, machining sequences and detailed information about a rectangular pocket and its machining operation will be explained. “Sequences” noted in Fig. 11.18 shows information about the machining sequence that is used to machine the test part. Every STEP-NC part program starts with the project entity (#1). The main purposes of the project are to define the sequence of machining processes by using the main workplan (#2) attribute and to define the workpiece information by using the workpiece (#4) attribute, which will be explained later. In this example, five machining workingsteps are executed sequentially. Firstly, the finishing operation for the planar face at the top (#10) is executed, and then the drilling operation (#11) and reaming operation (#12) are executed sequentially 412 11 STEP-NC System z y F1 1 z x y P2 P1 F2 P3 P4 F3 x 20 25 50 100 30 50 30 80 120 R1 R10 Fig. 11.17 Simple example test part for milling #1= PROJECT('EXECUTE EXAMPLE1',#2,(#4),$,$,$); #2= WORKPLAN('MAIN WORKPLAN',(#10,#11,#12,#13,#14),$,#8,$); #10= MACHINING_WORKINGSTEP('WS FINISH PLANAR FACE1',#62,#16,#19, #11= MACHINING_WORKINGSTEP('WS DRILL HOLE1',#62,#17,#20,$); #12= MACHINING_WORKINGSTEP('WS REAM HOLE1',#62,#17,#21,$); #13= MACHINING_WORKINGSTEP('WS ROUGH POCKET1',#62,#18,#22,$); #14= MACHINING_WORKINGSTEP('WS FINISH POCKET1',#62,#18,#23,$); #18= CLOSED_POCKET('POCKET1',#4,(#22,#23),#84,#65,(),$,#27,#35,#37,#28); #27= PLANAR_POCKET_BOTTOM_CONDITION(); #28= GENERAL_CLOSED_PROFILE($,#59); #59= POLYLINE('CONTOUR OF POCKET1',(#121,#122,#123,#124,#121)); #22= BOTTOM_AND_SIDE_ROUGH_MILLING($,$,'ROUGH POCKET1',15.000,$,,#39, #50,#41,$,#60,#61,#42,2.500,5.000,1.000,0.500); #60= PLUNGE_RAMP($,45.000); #61= PLUNGE_RAMP($,45.000); #42= BIDIRECTIONAL_MILLING(5.000,.T.,#43,.LEFT.,$); #41= MILLING_MACHINE_FUNCTIONS(.T.,$,$,.F.,$,(),.T.,$,$,()); #50= MILLING_TECHNOLOGY(0.040,.TCP.,$,12.000,$,.F.,.F.,.F.,$); #29= TAPERED_ENDMILL(#30,4,$,.F.,$,$); #30= MILLING_TOOL_DIMENSION(20.000,$,$,$,1.500,$,$); #39= MILLING_CUTTING_TOOL('MILL 20MM',#29,(#125),80.000,$,$); #4= WORKPIECE('SIMPLE WORKPIECE',#6,0.010,$,$,$,(#66,#67,#68,#69)); #6= MATERIAL('ST50','STEEL',(#7)); #7= PROPERTY_PARAMETER('E=200000N/M2'); #8= SETUP('SETUP1',#71,#62,(#9)); #9= WORKPIECE_SETUP(#4,#74,$,$,()); ISO-10303-21 HEADER; ENDSEC; DATA; } } Sequences Feature & Geometry Operation & Technology Tools Workpiece Data Heade r Fig. 11.18 ISO 14649 part program for test part for milling 11.5 Part Programming 413 for the round hole. Finally roughing (#13) and finishing (#14) operations for the closed pocket are executed. “Feature and geometry” shows feature information in the STEP-NC part program, especially closed pocket. In the part program, the bottom of the pocket is defined as the planar pocket bottom condition (#27). The general closed profile (#28), more especially polyline (#59), is used for the contour of the closed pocket. Table 11.2 Process plan for the closed pocket Closed pocket machine parameter Bottom and side Bottom and side rough milling finish milling Tool Taper End mill 20.0 Taper End mill 6.0 Retract plane 30 30 ADC 4 1 RDC 3 1 Strategy bidirectional milling Contour bidirectional Approach Plunge zigzag Plunge zigzag Retract Plunge ramp Plunge ramp Bottom allowance 1 0 Side allowance 1 0 Feedrate 250 250 Spindle speed 500 500 Coolant On on Chip removal On on Table 11.2 shows the process plan to remove the closed pocket of Fig. 11.17. In this example, the part program for the roughing operation will be explained. Machin- ing type is given by the bottom and side rough milling entity (#22) that has axial depth information (4.0), radial depth information (3.0) and finishing allowance for the wall (1.0) and bottom (1.0), the starting point and the overcut length. The machining strategy defines the method to execute the given machining oper- ation. The bidirectional milling entity (#42) is used in the process plan of Table 11.2. It defines the direction of the machining, step-overdirection and so on. If these values are omitted, the CNC can decide these values autonomously. The milling technology entity (#50) information defines machining conditions such as feed and spindle. Feed can be definedbyusingfeedrate or feedrate per tooth and the speed of the spindle can be defined by using spindle or cut speed. Additional information such as the con- current movement of spindle and feed, the override of the feed and spindle can be defined. In this example, feed per tooth is used to define feed and cut speed is used to define the cutting speed of the spindle. The milling machine function entity (#41) defines the activity of the machine tool such as air pressure, coolant, chip removal and so on. In Table 11.2, coolant and chip removal are used during machining. For the machining tool, taper endmill (#29) is used. It defines the diameter (20.0), edge radius (1.5), overall length (80.0) and number of cutting teeth (4). 414 11 STEP-NC System Information about the raw material of the part is defined by the workpiece entity in STEP-NC. In the existing method, G-code, there is no workpiece information. Only the operator knows the workpiece information and decides the cutting conditions by considering that information and generates the G-code. However, STEP-NC supports the initial and final shape of the raw workpiece, material of the workpiece, chucking position of the workpiece and so on. In this example, the material of the workpiece is steel named ‘ST-50’ and the initial shape of the workpiece is a block whose size is 100.0 ×120.0 ×50.0. 11.5.2 Part Programming for the Turning Operation Figure 11.19 shows a simple part for turning operation, described in the Annex D of ISO 14649 Part 12. Figure 11.20 shows the overall structure of the STEP-NC part program for the test part. The full version can be found in Annex D of ISO 14649 Part 12. 110 50 40 80 x z Workpiece coordinate system x z Outer_diameter(cylinder and cone) revolved_fla t Fig. 11.19 ISO Three levels of ISO 14649 data model The overall structure of the part program is similar to that for milling operations. The differences are the machining features, machining operations, machining tools that are used in turning. Therefore, turning feature (outer diameter), turning oper- ation (contouring rough) and turning tool (general turning tool) are explained here briefly. The shape of Fig. 11.19 includes an end face (revolved flat, #10), a cylin- der and a cone (outer diameter, #11 and #12). For the machining cylinder part (outer diameter, #12), the contouring rough (#22) operation is used. For the machin- ing strategy, unidirectional turning (#54) is assigned to execute contouring rough (#22). Unidirectional turning includes length of overcut, depth of cut (3 mm), change amount of feed, lift height (2 mm), feed direction, back path direction, stepover direction and the feed for each direction. For the cutting condition, turn- ing technology (#43) 0.3 mm per revolution is set as feed and 500 RPM is set as the spindle speed in the manner of constant spindle speed. For the machine func- tion, turning machine function (#40) defines that coolant should be used to carry out contouring rough. For the cutting tool, general turning tool (#100) is used and the 11.6 STEP-CNC System 415 #29=PROJECT('TURNING EXAMPLE 1',#30,(#1),$,$,$); #30=WORKPLAN('MAIN WORKPLAN',(#31,#32,#33,#34),$,#37,$); #31=MACHINING_WORKINGSTEP('WS ROUGH END FACE',#63,#10,#20,$); #32=MACHINING_WORKINGSTEP('WS FINISH END FACE',#63,#10,#21,$); #33=TURNING_WORKINGSTEP('WS ROUGH CONTOUR',#63,(#11,#12),#22,$); #34=TURNING_WORKINGSTEP('WS FINISH CONTOUR',#63,(#11,#12),#23,$) #10=REVOLVED_FLAT('END FACE',#1,(#20,#21),#70,#80,0.000,#91); #11=OUTER_DIAMETER('CONE',#1,(#22,#23),#76,#83,#93,#95); #12=OUTER_DIAMETER('CYLINDER',#1,(#22,#23),#78,#72,#74,$); #22=CONTOURING_ROUGH($,$,'ROUGH CONTOUR',$,$,#100,#43,#40,#56,#56,#54,0.500); #40=TURNING_MACHINE_FUNCTIONS(.T.,$,$,(),.F.,$,$,(),$,$,$); #43=TURNING_TECHNOLOGY($,.TCP.,#47,0.300,.F.,.F.,.F.,$); #47=CONST_SPINDLE_SPEED(500); #54=UNIDIRECTIONAL_TURNING($,$,(3.000),$,$,$,$,$,2.000,$,$); #56=AP_RETRACT_ANGLE($,45.000,4.000); #100=GENERAL_TURNING_TOOL('ROUGHING TOOL',120.0,45.0,$,$,$,#101,.LEFT.); #101=CUTTING_EDGE_ PROPERTIES (#102,$,$,10.0,110.0,$,25.0,(),$,$ #102= MATERIAL('TIN','TIN',()); #37=SETUP('SETUP FOR TURNING EXAMPLE 1',$,#63,(#38)); #38=WORKPIECE_SETUP(#1,#64,$,$,()); #1=WORKPIECE('SIMPLE WORKPIECE',#2,0.010,$,$,$,()); #2=MATERIAL('DIN EN 100271','E 295',(#3)); #3=NUMERIC_PARAMETER('ELASTIC MODULUS',2.E11,'pa'); ISO-10303-21 HEADER; ENDSEC; DATA; } } Sequences Feature & Geometry Operation & Technology Tools Workpiece Data Heade r Fig. 11.20 ISO 14649 part program for test part for turning overall length and width of its holder are 120 mm and 45 mm respectively. Also, general turning tool uses an insert which has cutting edge length (10.0 mm), side cutting edge angle (110.0 ◦ ) and end cutting edge angle (25.0 ◦ ). 11.6 STEP-CNC System As the new language is established, increasing attention is being paid to the devel- opment of a new CNC, STEP-CNC (or STEP-compliant CNC), operating based on ISO 14649. Since the new language accommodates various pieces of information about ‘what-to-make’ (i.e., product information including 3D geometry) and ‘how- to-make’ (process plan), STEP-CNC can undertake various intelligent functions that cannot be performedby conventional CNC operation based on ISO 6983. In this sub- section, the types of STEP-CNC and their architectures and related technology will be explained. As shown in Fig. 11.21, STEP-CNC has two types of interface bus, an external bus and an internal bus. The external bus, noted as “STEP based New Programming Language (ISO 14649)” in Fig. 11.21, connects CNC and the CAD/CAPP/CAM system. The information in the STEP-NC part program is interpreted and saved in the database according to its type e.g. CAD DB, CAPP DB, and CAM DB. The 416 11 STEP-NC System internal bus, noted as Soft Bus (CORBA) in Fig. 11.21, makes it possible for the various intelligent modules on the inside of the CNC controller to communicate with each other. CAD kernel CAD DB STEP IR AP203 AP224 CAPP kernel CAPP DB STEP IR ISO 13399 SP213 Part2 Part3 CAM kernel CAM DB Tool path STEP-based New Programming Language(ISO 14649) MMI Task Execution Task Planning Task Monitoring Soft Bus (CORBA) NCK PLC Embedded Kernel Configuration Layer Runtime Environment Fig. 11.21 STEP-NC interface architecture Considering the architecture, STEP-NC technology requires various technologies such as STEP interface technology, Autonomous machining technology, Open Ar- chitectural Controller technology, CNC technology, and CAD/ CAM/CAPP tech- nology, as shown in Fig. 11.22. These technologies can be classified into three types; 1) ISO 14649 related technologies, such as STEP interface technology and feature based CAD/CAM/CAPP technology; 2) ISO 14649 based intelligent and autonomous technologies, such as Open-architecture Soft-NC; NCK, PLC, Motion control, Autonomous task planning, On-line tool path generation, Feature-based exe- cution, Task monitoring, and Emergency handling; 3) Computer-aided programming technologies for generating STEP-NC part programs such as shopfloor programming systems. Details about open architecture controllers and soft-NC were explained in the previous chapter, this section shows the types and architectures of STEP-CNC. 11.6 STEP-CNC System 417 ISO 14649 Standard STEP Interface Technology Autonomous Machining Tech OAC/ Soft-NC Tech Etc. CNC Technology CAD/CAPP/ CAM/CAI STEP-NC Technology Fig. 11.22 STEP-NC related technologies 11.6.1 Types of STEP-CNC Depending on how STEP-NC is implemented on the CNC, there are three types of STEP-CNC: (1) conventional control, (2) new control, and (3) new intelligent control, as shown in Fig. 11.23. Type 1 simply incorporates ISO 14649 in a conventional controller via post- processing. In this case, conventional CNC can be used without modification. Strictly speaking, this cannot be considered as a STEP-compliant CNC as it should at least be able to read ISO 14649 code. Type 2, the ‘New Control’, has a STEP-NC inter- preter in it, through which the programmed workingstep is executed by the CNC kernel with built-in toolpath generation capability. Type 2 is the basic type where the motion is executed ‘faithfully’ based on the machining strategy and sequence as specified by the ISO 14649 part program. In other words, it does not have intelli- gent functions other than the toolpath generation capability. Most of the STEP-NC prototypes developed up to the present time fall into this category. Type 3, much more promising than the predecessors, is the ‘New Intelligent Control’ (Fig. 11.23), in which CNC is able to perform machining tasks ‘intelli- gently’ and ‘autonomously’ based on the comprehensive information of ISO 14649. Some examples of intelligent functions are automatic feature recognition, automatic collision-free toolpath generation including approach and retract motion, automatic tool selection, automatic cutting condition selection, status monitoring and automatic recovery, and machining status and result feedback. [...]... command 7 Tool radius compensation command 8 Spindle vibration detection command 9 Stroke limit input command 10 Cycle code command 11 Scaling command 12 Macro call command 13 Tool length compensation command 14 Work coordinate system selection command 15 Cutting mode command 16 Plane selection command 17 Polar coordinate command 18 Coordinate system rotation command 19 Return position setting command... of Korea STEP-NC: STEP -CNC system for milling • Development of TurnSTEP: STEP -CNC system for turning • Development of the data model for turning (ISO14649 Part 12 and 121) with ISW-University of Stuttgart • Suggestion and reflection on revision of the ISO14649 data model for milling • Promotion of international and domestic seminars for STEP-NC NRL-SNT developed two types of STEP -CNC system: Korea STEP-NC... PosMMI (Man–Machine Interface), and v) PosCNC For communication between these modules CORBA is used Korea STEP-NC is capable of execution of STEP-NC code without G-code and for direct interpolation of STEP-NC toolpaths using Soft-NC technology TurnSTEP for rotational parts fully supports ISO14649 Part 12 and 121 as a means for verifying the data model It is composed of three subsystems: i) CGS (Code-Generating... project to validate the use of STEP-NC in manufacturing applications This project, the Model-Driven Intelligent Control of Manufacturing (also known as the “Super Model” project), began in 1999 with the goal of using STEP-NC and other standards to develop an open database of all the information necessary to design and manufacture a part While NIST understands the value of standards-based data exchange,... – Inducement of implementation from partial to whole – Technology and service offered through Web services – Maximum utilization of accumulated know-how from R&D organizations Despite the short history of STEP-NC and on-going development of this standard, a large number of research works have been carried out across the whole world From the perspective of the STEP-NC data model, milling and turning... are composed of many CAD, CAM, CNC vendors and user groups With the development of STEPNC technology, the second type of STEP -CNC, having an ISO 14649 interpreter, will replace G-code-based controllers or the first type of STEP -CNC Finally, the third type STEP -CNC that enables performance of ‘intelligent’ and ‘autonomous’ machining based on the comprehensive information will dominate the CNC market Considering... Technology AP 213 Part2 Part3 STEP IR ISO 133 99 CAPP DB CAPP kernel Tool Tool path CAM DB CAM kernel Fig 11.23 Three types of STEP -CNC 11.6.2 Intelligent STEP -CNC Systems The requirements for the next-generation CNC are 1) from the data-level point of view, CAD data interface with a standard schema, internet interface, seamless information exchange should be considered, 2) from the functional-level point of view,... International Standards, EDM is in the process of being introduced, and other data models including the machine tool data model, inspection and rapid prototyping are currently in progress Simultaneously, the second edition versions of some ISO 14649 parts have been under development in order to complement the first versions From the perspective of STEP -CNC systems, current research for the first type of STEP -CNC, ... acquisition of the real geometry of the workpiece and its consideration for toolpath planning, provision of geometry information for NC integrated collision avoidance systems) A possible detailed layout of such a system and its seamless PDM integration with all other process planning software systems in order to enable true interoperable machining based on common and consistent data is one of the current... Sequence Graph (NPSG) - Generation of ISO 14649 part program - Interpretation/Edit of ISO 14649 part program CES (Code-edit System) • Input: ISO 14649 part program • Output: HPSG, EPSG • Functions - Interpretation of part program - Verification of logical contents - Generation of Hardwaredependent Process Sequence Graph (HPSG) - Generation of toolpath - Generation of Executable Process Sequence Graph . E of ISO 14649 Part 11. Figure 11.18 shows the overall structure of the STEP-NC part pro- gram for the test part of Fig. 11.17. Note that the part program of Fig. 11.18 is just a fraction of. machining strategy in Part 11 11.4.5 Tools for Milling and Turning This section deals with Part 111: “Tools for milling machines” and Part 121: “Tools for turning machines”. Part 111 and Part 121 define. IR CAD DB CAD kernel AP 213 STEP IR Part2 Part3 ISO 133 99 CAPP DB CAPP kernel Tool path CAM DB CAM kernel feedback Fig. 11.23 Three types of STEP -CNC 11.6.2 Intelligent STEP -CNC Systems The requirements