Dimensioning
标注尺寸
The design of a machine includes many factors other than those of determining the loads and stresses and selecting the proper materials.
机械设计除了计算载荷和应力、选择合适的材料外还包括许多其它因素。
Before construction or manufacture can begin, it is necessary to have complete assembly and detail drawings to convey all necessary information to the shop men. The designer frequently is called upon to check the drawings before they are sent to the shop. Much experience and familiarity with manufacturing processes are needed before one can become conversant with all phases of production drawings.
在建造或制造开始前完成装配图和零件图以把必要信息传达给车间工人是必须的。在送往车间前设计者常常被召集来检查图纸。而在精通生产图纸的所有情况之前需要有许多经验并熟悉制造工艺。
Drawings should be carefully checked to see that the dimensioning is done in a manner that will be most convenient and understandable to the production departments. It is obvious that a drawing should be made in such a way that it has one and only one interpretation.
图纸必须仔细检查其尺寸是否按生产部门最方便易懂的方式标注。很明显图纸应该只有唯一的解释。
In particular, shop personnel should not be required to make trigonometric or other involved calculations before the production machines can be set up. Dimensioning is an involved subject and long experience is required for its mastery.
尤其是不能要求车间工人在生产机械安排前进行三角或其它复杂的计算。 尺寸标注是一项复杂的工作要掌握它需要有丰富的经验。
Tolerances must be placed on the dimensions of a drawing to limit the permissible variations in size because it is impossible to manufacture a part exactly to a given dimension.
由于要把零件加工到正好为给定尺寸是不可能的因此图纸的尺寸必须加上公差以限制其可允许的变化。