課件英文版大連理工19th lecture

1、Mechanical drawing19th LectureRepresentations for workpieces(2)Lab of graphics study and communication, DUTSong HXSection 2 Sectional views (2)Prob.1Prob.2Prob.3Prob.4Prob.51. types of cutting planes1) A single cutting plane parallel with a principal projection plane (a full, a half or a broken-out

2、section is created by passing only one imaginary cutting plane through an object).AAAAFrom the number of cutting planes: Not parallel with any principal projection plane(create an auxiliary sectional view or auxiliary section(斜剖), it is a full or partial section).Labeling method：Application： When a

3、workpiece contains an inclined portion, the interior and exterior features are all needed to be represented.Arrange the auxiliary section like arranging an auxiliary viewAAAAAAAABBBB2) A set of parallel cutting planes (offset sectional view)AAAAAABB labeling method (as shown in the views)： applicati

4、on： Offset sections are used for complex workpieces which have a number of important features which should be sectioned with several parallel cutting planes.AAAAAAAABB Some problems： Do not use any line to represent turning point. The cutting plane lines are offset, the turning points must be perpen

5、dicular to the cutting plane lines and are not permitted to intersect the visible object lines, as shown in the views.AA Keep each part of the object complete and integrated. If their axial lines of two primitives are overlapped in one direction, the overlapped centerline can be used as boundary to

6、separate the two sectioned parts.AAAAAAincorrectcorrectAAAAAAAAAAAA3) Two or more than two intersecting cutting planes (aligned sections)AAAAA Labeling method (shown as the views)： Application： Aligned sections are used to represent details of a part that generally there is a common revolution axis

7、in. The cutting planes may pass through all of the nonaligned features in the unsectioned view. AA Some problems： Generally, the intersecting line of two imaginary cutting planes superpose the workpieces revolution axis. The rule of cutting, revolution, and then projecting is a very basic principle

8、for drawing aligned sectional view.AAAAA correctAAAAAAAAA Aligned sections are special types of orthographic views used to revolve or align special features of the part. In order to avoid Misunderstanding and being deformed , some features behind the cutting planes are not revolved with the cutting plane. Such as figure (a), but figure (b) is different from figure (a).A油孔AAAAFig. a螺孔AAAAAFig. bcorrect incorrectAAAAA If the imaginary cu