核电小孔径深孔管板的加工

Machining of the nuclear tube sheet with small hole diameter

秦山二期扩建工程热交换器的管板材料为00Cr19Ni10锻件,管板厚度为125mm,要求加工178-φ10.350+0.05孔,管孔排列形式为等边三角形排列,孔心距15mm,管孔粗糙度Ra3.2。核电厚管板高精度小孔的加工,首先采用导向套定位,利用枪钻和BTA钻分别试验,最终采用BTA钻内排屑方法钻孔成功。克服BTA钻的不利因素,找寻解决的方法。BTA钻直径φ10.34mm。加工后孔径尺寸为φ10.375～φ10.355mm,管孔椭圆度全部小于0.01mm,管桥尺寸都稳定在4.6mm,符合图纸要求。提出加工中注意的问题,为此类管孔的加工提供借鉴。

Regarding the tube sheet for the heat exchanger of Qinshan Phase Ⅱ extension project,its material is 00Cr19Ni10 forgings,the tube sheet thickness is 125 mm,requiring 178-φ10.350＋0.05 hole,the tube hole array shall take the shape of equilateral triangle,the center distance is 15 mm,and the tube hole roughness is Ra3.2.The guide sleeve shall be adopted for positioning prior to machining of the high precision small hole of the thick tube sheet,and the gun drill and BTA drill shall be adopted for testing,finally BTA drilling with internal chip removal shall be adopted,this method shall overcome the disadvantage factor of BTA drilling and shall be the new approach for drilling.The diameter of BTA drill is φ10.34 mm.The machined hole diameter shall be φ10.375-φ10.355 mm.The ellipticity of the tube hole shall be less than 0.01 mm,the pipe bridge dimension shall be 4.6 mm,conforming to the requirement of the drawing.The paper presents the precautions during machining so as to provide the reference for the similar pipe hole machining in the future.