組合零件加工工藝、程序編制及仿真設計.rar
摘要
數控機床的組成部分包括測量系統、控制系統、伺服系統及開環或閉環系統，在對數控零件進行實際程序設計之前，了解各組成部分是重要的。
數控中，測量系統這一術語指的是機床將一個零件從基準點移動到目標點的方法。目標點可以是鉆一個孔、銑一個槽或其它加工操作的一個確定的位置。用于數控機床的兩種測量系統是絕對測量系統和增量測量系統。絕對測量系統（亦稱坐標測量系統）采用固定基準點（原點），所有位置信息正是以這一點基準。換句話說，必須給出一個零件運動的所有位置相對于原始固定基準點的尺寸關系。X和Y兩維絕對測量系統，每維都以原點為基準。增量測量系統有一個移動的坐標系統。運用增量系統時，零件每移動一次，機床就建立一個新的原點（基準點）。使用增量測量系統時的X和Y值。注意，使用這個系統時，每個新的位置在X和Y軸上的值都是建立在前一個位置之上的。這種系統的缺陷是，如果產生的任何錯誤沒有被發現與校正，則錯誤會在整個過程中反復存在。
用于數控設備的控制系統通常有兩類，即點位控制系統和連續控制系統。點位控制數控系統機床（有時稱為位置控制系統數控機床）只有沿直線運動的能力。當沿兩軸線以等值（X2.000,Y2.000)同時編程時，會形成45度斜線。點位控制系統常用于需確定孔位的鉆床和需進行直線銑削加工的銑床上，以一系列小步運動形成弧形和斜線。然而，用這種方法時，實際加工軌跡與規定的切削軌跡略有不同。
Abstract
N/C machine tool elements consist of dimensioning system, servomechanisms and open- or closed-loop systems. It is important to understand each element prior to actual programming of a numerically controlled part.
The term measuring system in N/C refers to the method a machine tool uses to move a port from a reference point to a target point. A target point may be a certain location for drilling a hole, milling a slot, or other machining operation. The two measuring systems used on N/C machines are the absolute and incremental. The absolute (also called coordinate) measuring system uses a fixed reference point (origin). It is on this point that all positional information is based. In other words, all the locations to which a part will de moved must be given dimensions relating to that original fixed reference point. It shows an absolute measuring system with X and Y dimensions, each based on the origin. The incremental measuring system (also call delta) has a floating coordinating system. With the incremental system, the machine establishes a new origin or reference point each time the part is moved. It show X and Y values using an incremental measuring system. Notice that with this system, each new location bases its values in X and Y from the preceding location. One disadvantage to this system is that any errors made will be repeated throughout the entire program, if not detected and corrected.
There are two types of control systems commonly used on N/C equipment: point-to-point and continuous path. A point-to-point controlled N/C machine tool, sometimes referred to as a positioning control type, has the capability of moving only a straight line. However, when two axes are programmed simultaneously with equal values (X2.000 in., Y2.000 in.) a 45°angle will be generated. Point-to-point systems are generally found on drilling and simple milling machine where hole location and straight milling jobs are performed. Point-to-point systems can be utilized to generate arcs and angles by programming the machine to move in a series of small steps. Using this technique, however, the actual path machined is slightly different from the cutting path specified.
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