数控技术双语2.ppt

1、领域： 数控技术、CAD/CAM技术、柔性加工技术、集成制造 技术、智能制造技术、虚拟制造技术、绿色制造技术 趋势： 高精度、高效率、自动化、信息化、智能化 制造业数控化率年增长率达6%，据预测到2020年， 我国制造业数控化率将达到60%，正向制造业大国迈进。,NUMERICAL CONTROL TECHNOLOGY,Chapter 2 NC Part Programming,Electromechanical Engineering College Henan University of Science and Technology,.,Chapter 2 NC PART PROGRAMM

2、ING,2.1、Introduction to NC part programming 2.2、The codes used in CNC 2.3、Manual part programming 2.4、Automatic programming,.,Chapter 2 NC PART PROGRAMMING,2.1、Introduction to NC part programming,The program of instructions is the detailed step-by-step commands that direct the actions of the process

3、ing equipment. In machine tool applications, the program of instructions is called a part program, and the person who prepares the program is called a part programmer.,Numerical control (NC) is a form of automatically operating a machine tool based on coded alphanumeric data. A complete set of coded

4、 instructions for executing an operation is called a program. The program is translated into corresponding electrical signals for input to servo motors that run the machine.,.,Chapter 2 NC PART PROGRAMMING,1、Introduction to NC part programming,we call the whole process from part graphics to finishin

5、g control medium the programming of numerical control manufacturing, or call it NC programming. When using numerical control machine tool to manufacture parts, the programming is very important. The program is not only correct and fast but also effective and economic,.,Chapter 2 NC PART PROGRAMMING,

6、2.1.1 The contents and steps of numerical control programming,The program can be inputted into CNC system and the CNC system controls CNC machine tools to manufacture automatically. Generally speaking, the main steps of NC programming are analyzing part graphics, determining the manufacturing techno

7、logical process, calculating numerical value, programming, verifying the program and inputting the program into CNC system. Figure2.1 illustrates the programming steps.,.,Chapter 2 NC PART PROGRAMMING,2.1.1 The contents and steps of numerical control programming,Before NC programming, the programmer

8、 should understand the numerical control machine specifications, characteristics, the functions and programming instructions format of the CNC system, etc. When programming, he should analyze the parts technical requirements, geometrical shape, dimensions and technological requirements. Then he can

9、determine the manufacturing method and calculate numerical value, get cutter position. According to part dimension, cutter position value, cutting parameters (spindle speed, feed-rate, cutting depth ) and auxiliary functions(ATC,CW, CCW, coolant on and off), the programmer can program.,.,Chapter 2 N

10、C PART PROGRAMMING,2.1.1 The contents and steps of numerical control programming,Analyzing part graphics and determining the manufacturing technological process This step includes analyzing the part graphics, understanding the machining contents and requirements. Then determining technological proce

11、sses, machining plans, machining sequence, machining routes, fixing methods. Cutting parameters and selecting cutting tools, etc. Besides these, the numerical control machine codes should be understood clearly and the numerical control machine functions should be exploited fully.,.,Chapter 2 NC PART

12、 PROGRAMMING,2.1.1 The contents and steps of numerical control programming,Analyzing part graphics,Technological process,Selecting programing origin and coordinate system,Calculating numerical value,Writing The point is easy to find; The caused machining error is small.,.,Chapter 2 NC PART PROGRAMMI

13、NG,2.1.3 The Basis of NC Part Programming,2.1.3.2. The Technological Basis of NC Programming,(2). Selecting tool setting point and tool changing point rationally,.,Chapter 2 NC PART PROGRAMMING,2.1.3 The Basis of NC Part Programming,2.1.3.2. The Technological Basis of NC Programming,(3). Rationally

14、selecting the methods of fixing, cutting tools and cutting parameters,Selecting standard and common fixtures as far as possible, avoiding selecting special fixtures; Fixing and removing parts quickly,conveniently and rationally; The part surface to be machined should be exposed to outside.Dont let t

15、he fixture affect the rapid motion and machining of a tool.,.,Chapter 2 NC PART PROGRAMMING,2.2、THE CODES USED IN CNC,There are many codes included in a program. Preparatory functions are G codes and auxiliary functions are M codes. They are the base of CNC programs. ISO has worked out the standards

16、 of G codes and M codes. Because new CNC systems and machines have been emerging, a lot of functions in many systems surpass ISO standards. Their codes are abundant and their formats are flexible. They arent restrained by ISO standards.,.,Chapter 2 NC PART PROGRAMMING,2.2、THE CODES USED IN CNC,In ad

17、dition, even if the same function, its code and format have a lot of differences among systems made in different companies. And codes and formats also have differences between new and old systems made in the same company. But the preparatory functions codes and auxiliary functions codes in most of C

18、NC systems are up to or similar to the ISO standards. Before introducing the G codes and M codes, we must understand programming langue formats first.,.,Chapter 2 NC PART PROGRAMMING,2.2.1 Programming Language Format,A program format is a system of arranging information so that it is suitable for in

19、put to A CNC controller. Several different types of formats exist. The format to be used in this text is known as the word address.,(1) Addresses An address is a letter that describes the meaning of the numerical value following the address.,.,Chapter 2 NC PART PROGRAMMING,2.2.1 Programming Language

20、 Format,(2) Words Words are used to describe such important information . as machine motion and dimensions in the block. Program words are composed of two main parts: an address followed by a number.The Figure 2.9 illustrates the address, number and words.,.,Chapter 2 NC PART PROGRAMMING,2.2.1 Progr

21、amming Language Format,(3) Blocks A block is a complete line of information to the CNC machine. It is composed of one word or an arrangement of words. Blocks may vary in length. Thus, the programmer needs those words in a block to execute a particular machining function. “N10 G01X-63. 75Y70. 28F100.

22、S1000M03;”. Each block is separated from the next by an end of-block(;) code.,.,Chapter 2 NC PART PROGRAMMING,2.2.1 Programming Language Format,(3) Blocks The end-of-block character is automatically generated when the programmer presses return key at the computer. The same holds true when the end-of

23、-block key is pressed at the machine panel board during manual date entry.Thus,this character will not appear in the regular program listings in this text.,.,Chapter 2 NC PART PROGRAMMING,2.2.1 Programming Language Format,(4) Programs A program is a sequence of blocks that describe in detail the mot

24、ions a CNC machine is to execute in order to manufacture a part. The MCU executes a program block by block. The order in which the blocks appear is the order in which they are processed. Table 2.1 illustrates the format and the order in which the MCU executes a program. The order in which addresses

25、appear in a block can vary.,.,Chapter 2 NC PART PROGRAMMING,2.2.1 Programming Language Format,(5) Program and sequence numbers (O,N codes) (i) Program Number (O) Programs are stored in the MCU memory by program number. The machine recognizes programs according to a numeric code. Most machines can st

26、ore several programs at a time. Program numbers range from O0000 to O9999.,.,Chapter 2 NC PART PROGRAMMING,2.2.1 Programming Language Format,(5) Program and sequence numbers (O,N codes) (ii) Sequence Number (N) A sequence number is an optional tag that can be coded at the beginning of a block if nee

27、ded. The MCU will execute program blocks in the order in which they appear regardless of the sequence number entered. Sequence numbers are used so that operators can locate specific lines of a program when entering data or performing checkout operations.These numbers range from N0001 to N9999.,.,Cha

28、pter 2 NC PART PROGRAMMING,2.2.1 Programming Language Format,(6) Decimal point in programs Current CNC controls allow the programmer to include a decimal point for those words types that is feasible. For example, if a position along the X axis of 120.65 must be specified, the programmer would includ

29、e the world X120.65 in the command for the motion. Some words require the placement of a decimal point such as F,X,Y,Z,A,B,C,U,V,W,etc.,.,Chapter 2 NC PART PROGRAMMING,2.2.2 Preparatory Functions (G codes ),2.2.2.1 G codes,A preparatory function is designated by the address G followed by one or two

30、digits to specify a CNC machine how to move .G codes contain setting coordinates system, plane selection, interpolation, cutting tool compensation, canned cycle,etc.,.,Chapter 2 NC PART PROGRAMMING,2.2.2 Preparatory Functions (G codes ),2.2.2.1 G codes,A complete list of G codes is given in Appendix

31、 A.The G codes are divided into several groups according to their functions, such as a, b,c,dgroup,etc. Any two G Codes of a same group cant be in a block.The G codes of different groups can be in a block according to requirements.,.,Chapter 2 NC PART PROGRAMMING,2.2.2 Preparatory Functions (G codes

32、 ),2.2.2.2 The Introduction of G Codes Functions,(1) The G codes related to coordinate system,(a) Absolute dimension code G90 and incremental dimension code G91,G90 assigns the absolute mode of programming. The machine tool determines each new tool position from a home or specified origin (0,0). It

33、is important to include this command at the beginning of every tool, before any motion commands, to assure that the absolute command is selected.,.,Chapter 2 NC PART PROGRAMMING,2.2.2 Preparatory Functions (G codes ),2.2.2.2 The Introduction of G Codes Functions,(1) The G codes related to coordinate

34、 system,(a) Absolute dimension code G90 and incremental dimension code G91,G91 specifies that the incremental mode of programming to be used. Machine tools operating in this mode locate each new tool position by measuring from the last tool position established. We have stated that the better progra

35、mming mode is the absolute (90) programming mode, so you may question this command.,.,Chapter 2 NC PART PROGRAMMING,2.2.2 Preparatory Functions (G codes ),2.2.2.2 The Introduction of G Codes Functions,(1) The G codes related to coordinate system,(b) Assigning the work coordinate system G92,G92 belon

36、gs to fixture offsets. Fixture offset, also called work coordinate system multiple settings, allow the user to work with several coordinate systems within the same program. When it is convenient, if not mandatory, the programmer is able to set up more than one coordinate system in the program.,.,Cha

37、pter 2 NC PART PROGRAMMING,2.2.2 Preparatory Functions (G codes ),2.2.2.2 The Introduction of G Codes Functions,(1) The G codes related to coordinate system,(c) Selecting work coordinate system commands G54G59,G54G59 are separately called work coordinate system 1, work coordinate system 2 work coord

38、inate system 6. The six work coordinate systems are assigned through setting the offsets from machine coordinate system origin on the CRT panel.,.,Chapter 2 NC PART PROGRAMMING,2.2.2 Preparatory Functions (G codes ),2.2.2.2 The Introduction of G Codes Functions,(2) Selecting plane commands G17, G18

39、and G19,The three mutual perpendicular axes (X, Y, Z) in Cartesian coordinate system construct three planes. They are XY plane, XZ plane and YZ plane. Machining center selects these commands to control machining on these planes. Because turning center usually machines on XZ plane, the selecting plan

40、e command is not need. G17 illustrates machining on XY plane. G18 illustrates machining on XZ plane. G19 illustrates machining on YZ plane.,.,Chapter 2 NC PART PROGRAMMING,2.2.2 Preparatory Functions (G codes ),2.2.2.2 The Introduction of G Codes Functions,(3) The G codes related to tool movement,(a

41、) Rapid motion G00,This type of command is used to position the CNC machine to a location where some action is to occur. Under normal operation, the G00 command will cause the machine to move at its fastest possible rate. The rapid rates will vary from machine to machine. Several current CNC machine

42、s boast rapid rates-well over 24MPM. The machine will be moving very quickly while under the influence of a rapid motion command.,.,Chapter 2 NC PART PROGRAMMING,2.2.2 Preparatory Functions (G codes ),2.2.2.2 The Introduction of G Codes Functions,(3) The G codes related to tool movement,(b) G01 line

43、ar interpolation (Straight-Line motion),The second type of motion we will discuss causes the machine to move along a perfectly straight path in one or more axes. The control will calculate the path between the start point and the end point of the mo9tion automatically, no mater what angle is involve

44、d.,.,Chapter 2 NC PART PROGRAMMING,2.2.2 Preparatory Functions (G codes ),2.2.2.2 The Introduction of G Codes Functions,(3) The G codes related to tool movement,(c) Circular interpolation G02 and G03,Circular interpolation is performed in much the same way. Note the similarity in Figure 2.17. By con

45、touring, we mean making motions around the periphery of a shape. Contouring can include straight line and circular motion.,.,Chapter 2 NC PART PROGRAMMING,2.2.2 Preparatory Functions (G codes ),2.2.2.2 The Introduction of G Codes Functions,(3) The G codes related to tool movement,(c) Circular interp

46、olation G02 and G03,Circular interpolation involves two G words. The reason why there are two G words is to allow the programmer to specify the direction of the circular motion to be machined, clockwise motion (CW) or counterclockwise motion (CCW). To determine whether a particular motion is clockwi

47、se or counterclockwise, the programmer must look at the motion from the plus side of the uninvolved axis. If making a circular movement in X-Y, look at the motion from the Z plus side. If making a circular movement in X-Z, look at the motion from the Y plus side, and so on.,.,Chapter 2 NC PART PROGR

48、AMMING,2.2.2 Preparatory Functions (G codes ),2.2.2.2 The Introduction of G Codes Functions,(4) The G codes related to tool compensation,(a) Cutter radius compensation G41, G42 and G40,There are three G codes used in cutter radius compensation. Two of these G codes are used for instating or initiali

49、zing cutter radius compensation. Note that either G41 or G42 is used to instate cutter radius compensation. The third G code, G40, is used to cancel cutter radius compensation. Along with these three G codes, a programming word is also used to specify the offset number. Usually a D word is used to s

50、pecify the offset number.,.,Chapter 2 NC PART PROGRAMMING,2.2.2 Preparatory Functions (G codes ),2.2.2.2 The Introduction of G Codes Functions,(4) The G codes related to tool compensation,(b) Tool length compensation G43, G44 and G49,G43 is tool length positive compensation (compensating in + Z dire

51、ction). G44 is tool length negative compensation (compensating in Z direction). And G49 is the cancellation command for tool compensation. At machining, the actual lengths of tools are not equal to the specified length in programming. Figure 2.24 shows the tool length compensation. Included in the G

52、43 and G44 is an H word that tells the control which tool offset number is used as the tool length compensation. This H code is usually kept as the same number as the tool magazine number. For example, tool magazine 1 will use H code 1 (H01), tool magazine 2 will use H code 2 (H02), and so on.,.,Cha

53、pter 2 NC PART PROGRAMMING,2.2.2 Preparatory Functions (G codes ),2.2.2.2 The Introduction of G Codes Functions,(5) The G codes related to canned cycles G80-G89,The simplest operations to program are those related to producing holes. These include drilling, boring, tapping, spot drilling, reaming, a

54、nd counterboring. The simplicity of programming lies in the fact that the programming only needs to specify the coordinates of a hole center and the type of machine motions to performed at the center. A fixed cycle, if used properly, takes over and causes the machine motions to execute the required

55、movement. The controller stores a number of fixed cycles that can be recalled for use in programs when needed. This reduces the programming time and length of programs.,.,Chapter 2 NC PART PROGRAMMING,2.2.2 Preparatory Functions (G codes ),2.2.2.2 The Introduction of G Codes Functions,(5) The G code

56、s related to canned cycles G80-G89,Entering one block of information programs a canned cycle: the X and Y coordinates, the Z-axis clearance plane (R), and the final Z-axis depth. A fixed cycle for a hole operation will cause the following sequence of operation to occur: lRapid move to the X and Y co

57、ordinate of the hole center; lRapid move to the Z-axis clearance plane (R); l Feed to the Z-axis final depth; lRapid back to either the Z-axis initial position or the Z-axis clearance plane (R). .,.,Chapter 2 NC PART PROGRAMMING,2.2.2 Preparatory Functions (G codes ),2.2.2.2 The Introduction of G Co

58、des Functions,(5) The G codes related to canned cycles G80-G89,To perform the same operations in the next block, the programmer needs only to enter the X and Y coordinates of the next hole center. All canned cycles are modal. Once they are instated they will remain in effect until they are canceled

59、(by a G80 word). Figure 2.25 shows the example of drilling. In machining centers, G80-G89 are the commands usually used for canned cycles. And G80 is the command to cancel canned cycle. In turning centers, G33-G35 and G70-G79 are the commands usually used for canned cycles. .,.,Chapter 2 NC PART PROGRAMMING,2.2.3 Miscellaneous Machine Functions (M codes ),M codes are used to specify miscellaneous or auxiliary functions. M codes specify CNC machine functions