机械工程专业英语教程课后题翻译_1-4单元

Unit 1

Two methods of designating limit dimensions are considered as standard .One method is the maximum material method in which the large dimensions is placed above the smaller dimension for male parts, and the reverse is true for female parts. This method is well suited for small lot quantities because it is likely that the machinist himself may check the dimensions of the parts. In so doing, he will be verifying initially the larger dimension of the male part and the smaller dimension of the female part. The other method is the maximum number method and is preferred by production and quality control departments. In this method of designating a dimension, the larger number is always placed above the smaller number, regardless of whether the part is male or female.

这两种极限尺寸方法指定为标准。一个方法是最大的材料的方法，大尺寸放在上面的较小尺寸的凸圆零件，而相反的是真正的凹槽部分或内孔零件。这种方法非常适合小批量数量，因为它可能是，机械师可以检查尺寸的零件。在这样做时，他将核实最初尺寸较大的凸圆零件和较小尺寸凹槽部分。另一种方法是人数最多的方法是首选的生产和质量控制部门。在这种方法中指定尺寸，较大的数量总是放在上面的小数目，无论是凸圆零件或凹槽的一部分。

Unit2

0.4μm The finish is used for rapidly rotating shaft bearings, for heavily loaded bearings, for rolls in bearings of ordinary commercial grades, for hydraulic applications, for static sealing rings, for the bottom of sealing-rings grooves, for journals operating in plain bearings, and for extreme tension members.

0.4μm的终点是用于快速旋转的轴承，重载轴承，普通商业级的轧辊轴承，用于液压系统，静密封环，密封环槽的底部，轴颈操作平滑轴承，还适用一些有极大张力的零件。

Unit 3

1) From its inception, quantum mechanics had two apparently different mathematical forms: the

wave mechanics of E. Sehrodinger, which emphasizes the spatial probability distributions in the quantum states, and the matrix mechanics of W.Heisenberg, which emphasizes the transitions between states.

2) The rigid-body assumption cannot be used when internal stresses and strains due to the

applied forces are to be analyzed. Thus we consider the body to be capable of deforming. Such analysis is frequently called elastic-body analysis, using the additional assumption that the body remains elastic within range of the applied forces.

1）从成立以来，量子力学有两个明显不同的数学形式：浪潮力学的E. Sehrodinger的，它强调的是空间的量子态概率分布，与基体的W.Heisenberg，它强调的是状态之间的转换机制。

2）的刚性体的假设不能使用时，内部应力和应变由于施加的力以进行分析。因此，我们考

虑身体能够变形。这样的分析是经常被称为弹性体的分析，使用的额外的假设，身体的施加的力的范围内保持弹性。

Unit4

The relative velocity polygon method of performing a velocity analysis of a mechanism is one of several methods available. The pole represents all points on the mechanism having zero velocity. Lines drawn from the pole to points on the velocity polygon represent the absolute velocities of the corresponding points on the mechanism. A line connecting any two points on the velocity polygon represents the relative velocity for the two corresponding points on the mechanism.