Wednesday, October 24, 2007

怎样对不锈钢进行钻孔?钻孔时应注意哪些问题? www.tool-tool.com

Bewise Inc. www.tool-tool.com Reference source from the internet.

在不锈钢工件上钻孔常采用麻花钻,对淬硬不锈钢,可用硬质合金钻头,有条件时可用超硬高速钢或超细晶粒硬质合金钻头。钻孔时扭矩和轴向力大,切屑易粘结、 不易折断且排屑困难,加工硬化加剧,钻头转角处易磨损,钻头刚性差易产生振动。因此要求钻头磨出分屑槽,修磨横刃以减小轴向力,修磨成双顶角以改善散热条 件。

钻削不锈钢的典型钻头(即不锈钢群钻)。



图3中L≈0.32d0,L/2>L1>L/3,R≈0.2d0,h=0.04d0,b≈0.04d0。使用这种钻头钻削 1Cr18Ni9Ti时,对Ø20 mm、Ø25 mm、呾 mm三种直径的钻头,采用n=105 r/min,f=0.32 mm/r、0.4 mm/r、0.56 mm/r、0.67 mm/r四种不同的进给量,均可顺利地断屑和排屑。

还可采用不锈钢断屑钻头(图5)、S形硬质合金钻头(图6)、四刃带钻头(图7)及可转位硬质合金浅孔钻。






用不锈钢断屑钻头(图5)加工马氏体不锈钢2Crl3时,只需磨出E-E处断屑槽;而钻削加工lCrl8Ni9Ti奥氏体不锈钢时,还需加开A-A处断屑槽。不锈钢断屑钻头的具体参数及适用的钻削用量见表9。

表9 不锈钢断屑钻头的断屑槽和钻削用量

钻头直径d0
(mm)
半径RE
(mm)
宽度BA
(mm)
半径RE
(mm)
宽度BE
(mm)
主轴转速n
(m/min)
进给量f
(mm/r)
>8~15 3.0~5.0 2.5~3.0 2.0~3.5 1.0~2.5 210~335 0.09~0.12
>15~20 5.0~6.5 3.0~3.5 3.5~4.0 2.5~3.0 210~265
>20~25 6.5~7.5 3.5~4.5 4.0~4.5 2.8~3.3 170~210 0.12~0.14
>25~30 7.5~8.5 4.5~5.0 4.5~5.0 3.0~3.5 132~170

S形硬质合金钻头的特点是:无横刃,可减小轴向力50%;钻心处前角为正值,刃口锋利;钻心厚度增大,提高了钻头刚性;有两个喷切削液孔;圆弧形切削刃及排屑槽分布合理,便于切屑成小块,以利排出。

可 转位硬质合金浅孔钻的特点是:钻头前端不对称装有两片凸三角形刀片,分屑切除孔的不同部分,能自动定心,孔的直线性好,并且切入切出长度短;刀片前刀面 上带有多个坑状断屑槽,切削性能良好,尤其是断屑可靠,切屑呈一致的碎卷屑;内冷却使切削液直接喷向钻削加工表面,改善冷却效果,排屑非常通畅;特别是可 根据工件材料采用不同牌号的硬质合金刀片,切削速度达80~120m/min,钻削非常轻快。加工奥氏体不锈钢的钻削用量见表10。

表10 奥氏体不锈钢的钻削用量

钻头直径d0
(mm)
主轴转速n
(m/min)
进给量f
(mm/r)
≤5 1000~700 0.08~0.15
>5~10 750~500
>10~15 600~400 0.12~0.25
>15~20 450~200 0.15~0.35
>20~30 400~150
>30~40 250~100 0.20~0.40
>40~50 200~80

钻削不锈钢时,经常发现钻头容易磨损、折断,孔表面粗糙,有时出现深沟而无法消除;孔径过大,孔形不圆或向一边倾斜等现象。在操作时应注意下列事项:

1) 几何形状必须刃磨正确,两切削刃要保持对称。钻头后角过大,会产生“扎刀”现象,引起颤振,使钻出的孔呈多角形。应修磨横刃,以减小钻孔轴向力。

2) 钻头必须装正,保持钻头锋利,用钝后应及时修磨。

3) 合理选择钻头几何参数和钻削用量,按钻孔深度要求,应尽量缩短钻头长度、加大钻心厚度以增加刚性。使用高速钢钻头时,切削速度不可过高,以防烧坏刀刃。进给量不宜过大,以防钻头磨损加剧或使孔钻偏,在切入和切出时进给量应适当调小。

4) 充分冷却润滑,切削液一般以硫化油为宜,流量不得少于5~8 L/min,不可中途停止冷却,在直径较大时,应尽可能采用内冷却方式。

5) 认真注意钻削过程,应及时观察切屑排出状况,若发现切屑杂乱卷绕立即退刀检查,以防止切屑堵塞。还应注意机床运转声音,发现异常应及时退刀,不能让钻头在钻削表面上停留,以防钻削表面硬化加剧。


BW Bewise Inc. Willy Chen willy@tool-tool.com bw@tool-tool.com www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 TEL:+886 4 24710048 / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

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Bewise Inc. www.tool-tool.com

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