Milling machines
The milling machine（铣床） is a machine that removes metal from work with a revolving milling cutter（铣刀） as the work is fed against it.
The milling cutter is mounted on an arbor（刀杆） where it is held in place（定位） by spacers（垫片） or bushings（套筒）. The arbor is fixed in the spindle with one end, while the other end of the arbor rotates in the bearing mounted on the arbor yoke(刀杆座).
The most important parts of the milling machine are: 1) starting levers; 2) spindle; 3) column（立柱）; 4) knee（升降台）; 5) elevating screw（升降丝杠）; 6) table; 7) index head(分度头); 8) speed levers; 9) feed levers; 10) table movement levers; 11) foot stock（分度头支座）; 12) arbor yoke.
The spindle of the milling machine is driven by an electric motor through a train of gears mounted in the column.
The table of the plain milling machine（普通铣床） may travel only at right angles to the spindle while the Universal Milling Machine（万能铣床） is provided with a table that may be swiveled on the transverse slide(移动滑轨) for milling gear teeth, threads, etc.
Shaper（牛头刨床） and planer（龙门刨床）
The machine tools of this group are generally used for machining flat surfaces, which is usually performed by a cutter that peels the chip from the work. The main motion is reciprocating and the feed is normal (perpendicular)（垂直） to the direction of the main motion.
The tool and the apron（挡板） of a shaper are located on the ram（骨枕）. A chip is peeled off the work on the forward stroke. An adjustable table with “T” – slots holds work, vise, and other fixtures for holding the work.
The shaper has a rocker arm（摇臂） which drives the ram, and a mechanism for regulating the length of the stroke（冲程）. The ram supports the tool head. The head carries the down-feed （向下进刀imechanism and will swivel from side to side to permit the cutting of angles. This is generally hand feed, but some shapers are equipped with a power down-feed in addition to the regular hand down-feed.
The table of the shaper is of box form with iT” – slots on the top and sides for clamping（夹紧） the work. The cross rail（导轨） is bolted directly to the frame or column of the shaper with bolts.
The automatic feed or power feed is obtained by a pawl which engages in a notched wheel（棘轮） or ratchet（棘轮）.
The main parts of the planer include the bed, the table that moves back and forth, the column, the cross-rail（横梁） which moves up and down on the column, and the tool heads that are fastened to the cross rail.
Fig.13-3 Planer
Grinding machines（磨床）
A grinding machine is a machine which employs a grinding wheel（砂轮） for producing cylindrical, conical（圆锥的） or plane surfaces accurately and economically and to the proper shape, size, and finish. The surplus（多余的） stock（原料） is removed by feeding the work against the revolving wheel or by forcing the revolving wheel against the work.
There are a great variety of grinding machines. The machines that are generally used are cutter grinders（刀具磨床）, surface grindersy表面磨床）, centerless grinders（无心磨床）, external grinder（外圆磨床）, internal grinder（内圆磨床）.
Principal parts of a Plain Grinding Machine
1.Base（基座）. The main casting（主要铸件） of a plain grinding machine is a base that rests on the floor.
2.Table（工作台）. A sliding table.
Vocabulary
1.milling machine n. 铣床
2.milling cutter 铣刀
3.arbor n. 刀杆
4.spacer n. 垫片，垫圈
5.bushing n. 套
6.yoke n. 支座
7.starting lever 启动手柄
8.knee n. 升降台
9.elevating screw n. 升降丝杠
10.index head n. 分度头
11.foot stock n. 分度头支座
12.Universal Milling Machine n. 万能铣床
13.shaper n. 牛头刨床
14.planar n. 龙门刨床
15.ram n. 骨枕
16.vise n. 老虎钳
17.fixture n. 夹具
18.notched wheel/ratcher n. 棘轮
19.pawl n. 棘爪
20.cross rail n. 横梁
21.grinding machine n. 磨床
22.finish n. 表面粗糙度
23.cutter grinder n. 工具磨床
24.surface grinder n. 表面磨床
25.centerless grinder n. 无心磨床
26.internal grinder n. 内圆磨床
27.external grinder . 外圆磨床
28.wheel head n. 磨头
29.swivel n. 旋转
