重庆大学考研机械专业英语中文翻译大全(8)

件。他与台式机床差不多，不同是长圆柱固定在底座上。

Along that column is an additional, sliding table for fixing the workpiece which can be locked in position at any desired height. The power required for this type is more than that for the bench-type drilling machines.

Radial Drill摇臂钻床 A radial drill is particularly suitable for drilling holes in large and heavy workpieces that are inconvenient to mount on the table of an upright drilling machine. A radial drilling machine has a main column, which is fixed to the base. The cantilever guide arm, which carries the drilling head spindle and tool, can be raised or lowered along the column and clamped at any desired position. The drill head slides along the arm and provides rotary motion and axial feed motion. Again, the cantilever guide arm can be swung, thus enabling the tool to be moved in all directions according to a cylindrical coordinate system.

摇臂钻床特别适合在又大又重的工件上钻孔

After lathes, milling machines are the most widely used for manufacturing applications. In milling, the workpiece is fed into a rotating milling cutter, which is a multi-edge tool as shown in Fig.28.1. Metal removal金属切削 is achieved through combining the rotary motion of the milling cutter and linear motion of the workpiece

simultaneously.

车之后铣床被最广泛用于制造应用。铣削加工工件旋转输入铣刀,如图所示是一个多刃刀具。旋转运动与直线运动相结合，实现金属的切削加工。

Each of the cutting edges of a milling cutter acts as an individual single-point cutter when it engages with the workpiece metal. Therefore, each of those cutting edges has appropriate rake and relief angles. Since only a few of the cutting edges are engaged with the workpiece at a time, heavy cuts can be taken without adversely affecting the tool life. In fact, the permissible cutting speeds and feeds for milling are three to four times higher than those for turning or drilling. Moreover, the quality of surfaces machined by milling is generally superior to the quality of surfaces machined by turning, shaping, or drilling.

每个切削刃铣刀与金属接触时是单点切削。因此，每一个刀刃具有适宜的斜度与后角。因为同时有不止一个刀刃与工件接触，所以重力切削也不会对刀具产生大的影响，影响其寿命。事实上,其允许切削速度和进料速度是车削和钻孔的三到四倍。此外,由铣削加工表面质量通常比钻孔，刨削和车削要佔优势。

The milling process is characterized by: 铣削过程的特征是:

(1)Interrupted cutting. 适合间断性切割

Each of the cutting edges removes material for only a part of the rotation of the milling cutter. As a result, the cutting edge has time to cool before it again removes material. Thus the milling operation is much cooler compared to the turning operation.

每个刀刃旋转一次只切除一小部分的材料，因此，切削刃在下次切除材料之前有足够的时间冷却。因此相对于车削加工，铣削加工的刀片温度更加低。

(2)Small size of chips.体积小 Though the size of the chips is small, in view of鉴于，由于 the multiple多重 cutting edges in contact a large amount of material is removed and as a result the component is generally completed in a single pass unlike the turning process which requires a large number of cuts for finishing.

虽然刀片的尺寸小，但是由于有多重切削刃与工件接触，有很大量的材料在仅仅是一次玩完整的过刀中被切下来。而不像车削那样，为了达到最终要求需要切很多次。

(3)Variation in chip thickness.碎片厚度的变化 This contributes to the non-steady不稳定 state状态 cyclic conditions循环条件 of varying cutting forces during the contact of the cutting edge with the chip thickness varying from zero to maximum size or vice versa反之亦然. This cyclic variation循环变化 of the force can excite激发 any of the natural frequencies固有频率 of the machine tool system and is

harmful to the tool life and surface roughness generated.

这是有利于那种不稳定状态循环条件 变化的切削力在切削刃与切削厚度之间的接触 从零变到最大或者反之亦然。这个循环变化的力量能够激发任何机床系统的固有频率并且这是有害于表面粗糙度和刀具寿命的。

As far as the directions of cutter rotation and workpiece feed are concerned, milling is performed by either of the following two methods.

至于刀具旋转方向以及材料进给方向的关系,铣削由以下二种情况。

Up milling (conventional milling). In up milling the cutting tool rotates in the opposite direction to the table movement, the chip starts as zero thickness and gradually increases to the maximum size as shown in Fig.28.2(a). This tends to lift the workpiece from the table. There is a possibility that the cutting tool will rub the workpiece before starting the removal. However, the machining process involves no impact loading冲击载荷, thus ensuring smoother operation of machine tool.

逆铣(传统的，惯用的铣)。铣削刀具与工作平面以相反方向运动，切削的厚度从零开始，逐步增加到的最大值,如图Fig.28.2(a)。这可能会把工件弄出工作平台。有可能，在切削开始之前刀具就与工件接触。然而，加工过程不包括冲击载荷，因此需要确保机器工具的平稳工作。

The initial rubbing最初的摩擦 of the cutting edge during the

start of the cut in up milling tends to dull the cutting edge and consequently因此 have a lower tool life. Also since the cutter tends to cut and slide alternatively, the quality of machined surface obtained by this method is not very high. Nevertheless, up milling is commonly used in industry, especially for rough cuts粗削.

在你洗开始的阶段的这种摩擦会弄顿刀刃因此这种刀的寿命会缩短。还有由于此时切割与打滑刀具要选其一，加工件的表面质量又得不到保证很高。然而，不过逆铣在生产中只要不是粗削都常用这个。

Down milling (climb milling). In down milling the cutting tool rotates in the same direction as that of the table movement, and the chip starts as maximum thickness and goes to zero thickness gradually as shown in Fig.28.2 (b). This results in a kind of impact影响, or sudden loading. Therefore, this method cannot be used unless the milling machine is equipped with a backlash eliminator on the table lead screw. The maximum depth of cut is achieved directly直接 as the cutter刀具 engages参与 with the workpiece and this gives a large force, which will have to be taken care of by a rigid严格 lead screw导螺杆 for table feeding工作台进给.

顺铣。铣削刀具与工作平面以相同方向运动，切削的厚度从最厚开始，逐步减少到的零。用这种方法会有突如其来的载荷。因此除非在在机床导螺杆上装了齿轮消除装置，不然这样不好。刀具与工件刚刚接触的时候就达到了最大切割深度，而有了最大的力。因此必须严

格遵循导螺杆调节进行工作进给。

The advantages of this method include higher quality of the machined surface and easier clamping of workpiece, since cutting forces act downward. Down milling also allows greater feeds per tooth and longer cutting life between regrinds than up milling. But, it cannot be used for machining castings or hot rolled steel, since the hard outer scale will damage the cutter.

这种方法的优点包括高质量的机械加工面还有工件更易夹持。因为切削力大小是下滑的。顺铣可以有更大的进给量和更长的寿命。但是不能用于铸件加工还有热轧钢。因为坚硬的表面会伤害刀刃。

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