8.3 零件上常见的工艺结构（课件）-《机械制图》同步精品课堂（劳保版 ·第8版）

第八章 零件图 8.3 零件上常见的工艺结构 同步精品课堂 同步精品课程——中职专业课 《机械制图》 中国劳动社会保障出版社 1 导入新课 2 探究新知 3 应用新知 4 展示评价 Contents 目 录 5 课堂小结 6 布置作业 01 导入新课 We have many PowerPoint templates that has been specifically designed to help anyone that is stepping into the world of PowerPoint We have many templates that has been specifically designed to help anyone 除了基本几何形状外，还有哪些特殊的结构？ 它有什么作用呢？ 观看下图,并展开讨论 导入新课 02 探究新知 We have many PowerPoint templates that has been specifically designed to help anyone that is stepping into the world of PowerPoint We have many templates that has been specifically designed to help anyone 在铸件的内、外 壁沿起模方向应有一定的斜度 (1∶20~1∶10) 1.起模斜度 一、铸造工艺结构 探究新知 2.铸造圆角 在铸件转角处应做成圆角，否则砂型在尖角处易落砂到熔融的金属中；同时金属在冷却收缩过程中，尖角处易产生裂纹或缩孔。 a a 转角处做成圆角 R R1 R=( ~ )a 3 1 1 5 R1=a 探究新知 铸件壁厚不均匀时，冷却速度不同，易形成缩孔或裂纹，设计时，壁厚应尽量均匀。 3.铸件壁厚 探究新知 ⒈ 倒角和倒圆 二、机械加工工艺结构 通常在轴及孔端部倒角。 作用：便于装配和操作安全。  b× b  倒角宽度b按轴（孔）径查标准确定。 =45°，也可取30°或60°。 探究新知 ⒉ 退刀槽和砂轮越程槽 作用：便于退刀和零件轴向定位。 探究新知 3.凸台和凹坑 作用：减少机械加工量及保证两表面接触良好。 探究新知 探究新知 4.钻孔结构 作用：避免钻孔偏斜和钻头折断。 90° 探究新知 03 应用新知 We have many PowerPoint templates that has been specifically designed to help anyone that is stepping into the world of PowerPoint We have many templates that has been specifically designed to help anyone 一.判断工艺是否合理 自主探究 可用作内切圆方法检查，内切圆的直径差别不能大于20－25%。 厚度尽量一致，防止局部肥大 不正确 正确 不正确 正确 作内切圆 作内切圆 应用新知 小组合作 二、请指出下零件图设计中采用了哪种工艺结构，并用红色线段突出显示。 探究新知 小组合作 答案 探究新知 三、判断工艺是否合理，并说明原因 不好 好 不好 好 好 利用凹进减少加工面积 利用凹进减少加工面积 利用凸起减少加工面积 组间PK 应用新知 04 展示评价 We have many PowerPoint templates that has been specifically designed to help anyone that is stepping into the world of PowerPoint We have many templates that has been specifically designed to help anyone 小组代表分享： 零件上常见的工艺结构 一组 二组 三组 互评 师评 自评 展示评价 05 课堂小结 We have many PowerPoint templates that has been specifically designed to help anyone that is stepping into the world of PowerPoint We have many templates that has been specifically designed to help anyone 零件上常见 的工艺结构 课堂小结 06 布置作业 We have many PowerPoint templates that has been specifically designed to help anyone that is stepping into the world of PowerPoint We have many templates that has been specifically designed to help anyone 相关习题 习题册 联系实际 解读图纸 布置作业 感谢观看 $$