【正文】 enerally speaking, the motion type (rapid, linear, and circular), the axes to move, the amount of motion and the motion rate (feedrate) are programmable with almost all CNC machine tools. A CNC mand executed within the control tells the drive motor to rotate a precise number of times. The rotation of the drive motor in turn rotates the ball screw. And the ball screw drives the linear axis (slide). A feedback device (linear scale) on the slide allows the control to confirm that the manded number of rotations has taken place3. Refer to . Though a rather crude analogy, the same basic linear motion can be found on a mon table vise. As you rotate the vise crank, you rotate a lead screw that, in turn, drives the movable jaw on the vise. By parison, a linear axis on a CNC machine tool is extremely precise. The number of revolutions of the axis drive motor precisely controls the amount of linear motion along the axis. How axis motion is manded understanding coordinate systems It would be infeasible for the CNC user to cause axis motion by trying to tell each axis drive motor how many times to rotate in order to mand a given linear motion amount4. (This would be like having to figure out how many turns of the handle on a table vise will cause the movable jaw to move exactly one inch!) Instead, all CNC controls allow axis motion to be manded in a much simpler and more logical way by utilizing some form of coordinate system. The two most popular coordinate systems used with CNC machines are the rectangular coordinate system and the polar coordinate system. By far, the more popular of these two is the rectangular coordinate system. The program zero point establishes the point of reference for motion mands in a CNC program. This allows the programmer to specify movements from a mon location. 畢 業(yè)設(shè)計（外文翻譯 ） 3 If program zero is chosen wisely, usually coordinates needed for the program can be taken directly from the print. With this technique, if the programmer wishes the tool to be sent to a position one inch to the right of the program zero point, is manded. If the programmer wishes the tool to move to a position one inch above the program zero point, is manded. The control will automatically determine how many times to rotate each axis drive motor and ball screw to make the axis reach the manded destination point . This lets the programmer mand axis motion in a very logical manner. Refer to , 3. All discussions to this point assume that the absolute mode of programming is used6. The most mon CNC word used to designate the absolute mode is G90. In the absolute mode, the end points for all motions will be specified from the program zero point. For beginners, this is usually the best and easiest method of specifying end points for motion mands. However, there is another way of specifying end points for axis motion. 畢 業(yè)設(shè)計（外文翻譯 ） 4 In the incremental mode (monly specified by G91), end points for motions are specified from the tool39。s theory, Machining with high cutting speeds... on which, in 1931, took out a German patent, assumes that at a certain cutting speed (510 times higher than in conventional machining), the chip removal temperature at the cutting edge will start to decrease... Given the conclusion: ... seems to give a chance to improve productivity in machining with conventional tools at high cutting speeds... Modern research, unfortunately, has not been able to verify this theory totally. There is a relative decrease of the temperature at the cutting edge that starts at certain cutting speeds for different materials. The decrease is small for steel and cast iron. But larger for aluminum and other nonferrous metals. The definition of HSM must be based on other factors. Given today39。t expect the machine to correct the fault. Don39。t turn, remember that the spindle is connected to the gear box, which is connected to the spindle motor, which is driven by the spindle drive, which is connected to the I/O BOARD, which is driven by the MOCON, which is driven by the processor. The moral here is don39。t start randomly changing parts and parameters. Remember, there is a good chance that if you change something, you will incorrectly install it or break something else in the process6. Consider for a moment changing the processor39。 各種數(shù)控機床的第一個優(yōu)點是自動化程度提高了。由于機床在程序的控制下運行，與操作普通機床的機械師要求的技能水平相比，對數(shù)控操作員的技能水平要 求（與基本加工實踐相關(guān)）也降低了。 大多數(shù)數(shù)控機床的第三個優(yōu)點是柔性強。由于這些機床很容易調(diào)整并運行，也由于很容易裝載加工程序，因此機床的調(diào)試時間很短。各種數(shù)控設(shè)備有兩個或多個運動方向，稱為軸。通常，幾乎所有的數(shù)控機床的運動類型（快速定位、直線插補和圓弧插補）、移動軸、移動距離以及移動速度（進給速度）都是可編程的。旋轉(zhuǎn)虎鉗搖柄就是旋轉(zhuǎn)絲杠，絲杠帶動虎鉗鉗口移動。數(shù)控機床上使用最廣泛的兩種坐標系是直角坐標系和極坐標系。如果編程零點選擇恰當，程序所需坐標通?？蓮膱D紙上直接獲得。這使編程員以非常合理的方式命令軸的運動，參見圖2 和圖 3. 理解絕對和相對運動 至此，所有的討論都假設(shè)采用的是絕對編程方式。 增量方式（通常用 G91 指定）下，運動終點的指定是以刀具的當前位置為起點，而不是編程零點。如果工作在絕對方式（初學(xué)者應(yīng)該如此），編程員應(yīng)始終在 問“刀具應(yīng)該移動到什么位置？”，這個位置是相對于編程零點這個固定位置而言，而不是相對于刀具當前位置。指定編程零點的方式隨數(shù)控機床和數(shù)控系統(tǒng)的不同而很不相同。 另一種較新、更好的指定編程零點的方法是通過偏置的形式，見圖 4。 2. FMC 能制造的零件族的數(shù)目 有限。在過去的 60 年中，高速加工己經(jīng)畢 業(yè)設(shè)計（外文翻譯 ） 5 廣泛應(yīng)用于金屬與非金屬材料，包括有特定表面形狀要求的零件生產(chǎn)和硬度高于或等