机械制造技术基础英文课件CHAPTER1(8)

（2）Longitudinal turningAccording to the definition of the resultant speedη：ftanη= ?dwwhere f－feed ratedw－the diameter of the surface to be machined on the designated point A of the cutting toolConverse it to the main section：tanη0＝tanη.sinkr；γ0e＝γ0＋η0（1.20）We know from formula 1.20：η is not only related with feed rate f, but also related with the work diameter dw；the smaller dw，the bigger of the angle variation.1.1.4.2 Working angles influenced by tool setup（1）Influenced by tool tip setupWhen the tool tip is higher than the center of the work, the working cutting edge plane will be turned into Pse，working reference plane into Pre，working angleγpebecomes increases，αpedecreases。In the longitudinal plane P－P, the variation hof θpis ：tanθp＝?dw?2???h?2?2（1.21）Where h－the deviation from the tool tip to the work center line（mm）；dw－diameter of the work（1）Influenced by tool tip setupThe working angles ：γpe＝γp＋θpor αpe＝αp－θp（1.22）The above angles are marked in the system（Pp－Pp），they should be converted into the working main section plane：tanθ0＝h?dw?2?h???2?2coskr（1.23）?0e??0??0；or a0e?a0??0（1.24）（2）Influenced by the tool bar setup

If the tool bar is not perpendicular to the feed direction,the working cutting edge angle kreand minor cutting edge angle k’rewill change：

k0e?kr?G；

k're?k'r?G（1.25）

Where G—angle formed by predetermined feed section and working feed section，measured on the reference plane。It is also the angle formed by the normal line of feed direction and the center line of the tool bar

1.1.5 parameters of the cutting layer and cutting mode1.1.5.1 cutting layerAll the cutting parameters can be explained by the typical cylindrical turning,shown as Fig.1.19. The motional path of any designated point on the cutting edge relative to the workpiece is a spatial helix .The definition and explanation are as follows：Feed, the move distance of the cutting tool per workpiece revolution（f，mm/r）.Cutting layer,the layer where the metal is being cuttedIn longitudinal turning, and when k?r＝0、λs＝0，the the cutting layer geometry is parallelogramUnder special situation（kr＝90°）it is rectangle.

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