《機械製圖》——機件的常用表示式（3）

今天我們學習《機械製圖》——機件的常用表達方法第三部分的內容。今天的主要內容是斷面圖。Today we study “Mechanical Drawing” - the third part of the common methods of expression of machine parts。 Today‘s main content is the cross-sectional drawing。

No.1 斷面圖的基本概念

1。假想用剖切面將物體的某處切斷，僅畫出該剖切面與物體接觸部分的圖形，這個圖形稱為斷面圖，可簡稱斷面。通常在斷面圖上畫出剖面符號，斷面圖常用來表示機件上某一佈局的斷面形狀，如機件上的肋，輪輻，以及軸上的鍵槽和孔等。

2。斷面圖與剖檢視的區別：斷面圖只畫出機件的斷面形狀，而剖檢視則將機件處在觀察者和剖切平面之間的部分移去後，除了斷面形狀以外，還要畫出機件留下部分的陰影。

1。 Assume that the object will be cut off somewhere with a section， only draw the section and the object contact part of the figure， the figure is called a section drawing， can be referred to as a section。 Usually in the section drawing drawn on the section symbol， section drawing is often used to indicate the shape of a layout on the machine section， such as the rib on the machine， the spokes， and the keyway and hole on the shaft。

2。 The difference between cross-sectional drawing and sectional view： cross-sectional drawing only draws the cross-sectional shape of the machine part， while the sectional view will be removed from the part between the observer and the cut plane， in addition to the shape of the cross-section， but also draw the part of the machine left in the shadow。

No.2斷面圖的分類

斷面圖分為移出斷面圖和重合斷面圖，通常也簡稱移出斷面和重合斷面。

（一）。移出斷面圖：畫在檢視外的斷面，稱為移出斷面。

1。移出斷面的輪廓線用粗實線繪製，配置在剖切線（細點畫線）的延長線上；

2。斷面圖形對稱時，畫在檢視的中斷處；

3。在不引起誤解時，允許將圖形旋轉，移出斷面在旋轉後，加註旋轉方向的符號，並使符號的箭頭端靠近圖名的拉丁字母；

4。由兩個或多個相交平面剖切得出的移出斷面，中間應斷開；

5。當剖切平面透過迴轉面形成的孔或凹坑的軸線時，則這些結構應按剖視繪製；

6。當剖切平面透過非圓孔，會導致出現完全分開的兩個斷面時，則這些結構應按剖視繪製。

（二）。重合斷面圖

在不影響圖形清晰條件下，斷面也可按投影關係畫在檢視內。畫在檢視內的斷面稱為重合斷面。重合斷面的輪廓線用細實線繪製。當檢視中的輪廓線與重合斷面圖形重疊時，檢視中的輪廓線仍應連續畫出，不可間斷。

Cross-sectional diagrams are divided into move-out cross-sectional diagrams and reunited cross-sectional diagrams， usually also referred to as move-out cross-sectional and reunited cross-sectional。

（a）。 Move out of the section drawing： drawn outside the view of the section， known as move out of the section。

1。 move out of the section of the contour line drawn with a thick solid line， configured in the section line （fine dotted line） on the extension line。

2。 drawn at the interruption of the view when the section figure is symmetrical。

3。 when not causing misunderstanding， it is allowed to rotate the figure， moving out of the section after rotation， adding the symbol for the direction of rotation and keeping the arrow end of the symbol close to the Latin letter of the figure name。

4。 removed sections derived from two or more intersecting planes of dissection， which should be broken in the middle。

5。 when the section plane passes through the axis of the hole or pit formed by the rotary surface， then these structures shall be drawn in section。

6。 when the sectioning plane passes through a non-circular hole， which would result in two completely separated sections， then these structures shall be drawn in profile。

（ii）。 Overlapping section drawing

Without affecting the graphic clarity conditions， the section can also be drawn in the view according to the projection relationship。 The section drawn in the view is called a rejoined section。 The contour line of the overlapping section is drawn with a thin solid line。 When the contour line in the view and the overlap section graphics， the contour line in the view should still be drawn continuously， not interrupted。

參考資料：文字：百度；圖片：微博；翻譯：百度翻譯

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