1、Unit 11TEXT READING MATERIAL Unit 11Unit 11TEXTDrills and Drilling Machines The twist drill is a very efficient tool. It is generally formed by forging and twisting grooves in a flat strip of steel or by milling a cylindrical piece of steel, high-speed steel being commonly used. High-speed steel cos

2、ts more but tools made of it withstand heat much better than those made of ordinary tool steel. The twist drill may be divided into three principal parts: body, shank, and point. The flutes are the spiral grooves that are formed on the side of a drill, drills being made with two, three, or four flut

3、es. Those having three or four flutes are used for following smaller drills or for enlarging holes already drilled, and are not suited for drilling into solid stock. Unit 11Fig.11-1 The twist drillUnit 11 Spiral flutes have four main advantages: (1) They give the correct rake to the lip of a drill.

4、(2) They cause the chip to curl so tightly that it occupies the minimum amount of space. (3) They form channels through which chips escape from the hole. (4) They allow the lubricant to flow easily down to the cutting edge. The margin is the narrow strip on the cutting edge of the flute. It is pract

5、ically the full diameter of the drill and extends the entire length of the flute, its surface being a part of a cylinder. The portion of the body next to the margin is of less diameter than the margin. This lessened diameter, called body clearance, reduces the friction between the drill and the wall

6、s of the hole, while the margin insures the hole being of accurate size. Unit 11 The shank is the end of the drill which fits into the socket, spindle, or chuck of the drill press. The tang is usually found only on tapered shank tools. The drilling machine is the second oldest machine tools, having

7、been invented shortly after the lathe, and is one of the most common and useful machines. The drilling machines may be classified into three general types: vertical spindle, multiple spindle, and radial spindle machine. The vertical spindle drilling machine comes in three types: heavy duty, plain, a

8、nd sensitive. Besides the drilling of holes, such operations may be performed on the drilling machine: drilling, tapping (internal threading), reaming (finishing the hole with a reamer), countersinking, counterboring, boring and spot-facing.Unit 11Fig.11-2 Drilling machine operations Unit 11LEARN TO

9、 SPEAK Li Ying:Good morning, Teacher Wang.Teacher Wang:Good morning, Li Ying. Li Ying:What are you doing?Teacher Wang:I am drilling a hole in this work-piece.Li Ying:Whats this?Teacher Wang:It is a drilling machine.Li Ying:What can we do with the drilling machine?Teacher Wang:It can be used for mach

10、ining holes.Li Ying:Is the twist drill a very efficient tool?Teacher Wang:Yes. It is.Li Ying:What material is the twist drill generally made of ?Teacher Wang:It is usually made of high-speed steel.Unit 11Li Ying:How many parts may the twist drill be divided into ?Teacher Wang:It may be divided into

11、three principal parts: body, shank and point.Li Ying:How many flutes are there on the twist drill?Teacher Wang:There are two, three, or four flutes.Li Ying:Could you tell me about the history of drilling machine.Teacher Wang:Of course! The drilling machine is the second oldest machine, having been i

12、nvented shortly after the lathe, and is one of the most common and useful machines.Li Ying:Oh, I see. Thank you, Teacher Wang. Bye-bye.Teacher Wang:Bye!Unit 11NEW WORDS AND EXPRESSIONSefficient I5fIFEnt adj. 有效率的，能干的principle 5prInsIp(E)l adj. 主要的，首要的body 5bBdI n. 體，鉆體shank FANk n. 鉆柄point pCInt n.

13、點，刀尖，鉆尖flute flu:t n. 凹槽，螺旋槽spiral 5spaIEr(E)l adj. 螺旋形的，螺紋的rake reIk n. 前角lip lIp n.緣，刀刃，切削刃Unit 11chip tFIp n. 碎屑，切屑curl k:l v. 使卷曲，使卷邊channel 5tFAnEl n. 通道，溝槽lubricant 5lu:brIkEnt n. 滑潤劑margin 5mB:dVIn n. 刃帶，邊界，界限lessen 5les(E)n v. 減少，減輕socket 5sBkIt n. 鉆套，插口tang tAN n. 柄舌sensitive 5sensItIv adj.

14、 敏感的tapping 5tApIN n. 攻絲，攻螺紋，穿孔Unit 11threading WredIN n. 攻絲，車螺紋countersinking 5kaJntE(r)sINkIN n. 尖底锪鉆counterboring 5kaJntE(r)bR:rIN n. 平底锪鉆boring bR:rIN n. 鏜孔spiral groove 螺旋槽body clearance 鉆體間隙spot facing 锪端面Unit 11NOTES 1It is generally formed by forging and twisting grooves in a flat strip of s

15、teel or by milling a cylindrical piece of steel, high-speed steel being commonly used. 它通常由扁鋼鍛造后扭轉出凹槽，或由圓柱形棒料銑削而成，一般由高速鋼制作。 “，high-speed steel being commonly used”是被動形式的分詞獨立結構，它用來對句子的意思加以補充，可直接譯成相當于漢語的一個句子。本句結構為“名詞+being+過去分詞”。Unit 11 在本課中類似的結構還有“，drills being made with two, three, or four flutes.”

16、2High-speed steel costs more but tools made of it withstand heat much better than those made of ordinary tool steel. 高速鋼的成本雖然較高，但用它制作的刀具在耐熱性方面要比用普通工具鋼好得多。 3They cause the chip to curl so tightly that it occupies the minimum amount of space. (螺旋槽)卷緊切屑, 使其占有最小空間。 4It is practically the full diameter o

17、f the drill and extends the entire length of the flute,its surface being a part of a cylinder.Unit 11 (刃帶部分)實際上是鉆頭的最大直徑處，它伸展到螺旋槽的全長，刃帶的表面是圓柱體的一部分。 5The drilling machine is the second oldest machine tool, having been invented shortly afer the lathe, 鉆床是僅次于車床的最古老的機床，它的發明略晚于車床(它在車床發明之后不久就被發明了)。 6The Ve

18、rtical Spindle Drilling Machine comes in three types:Heavy Duty,Plain,and Sensitive. 立式鉆床有三種類型：重型鉆床，普通鉆床和高速手壓臺鉆。 Unit 11EXERClSES 1Place a“T”after sentences that are true and an“F”after those that are false. (1) The drilling machine is the second oldest machine tool,having been invented shortly befo

19、re the lathe.( ) (2) The spiral flute of a drill cause the chip to curl so tightly that it occupies the maximum amount of space.( ) (3) In addition to drills, other tools such as reamers,countersinks,counterbores and boring heads can also be used.( ) (4) Spiral flutes allow the lubricant to flow eas

20、ily down to the cutting edge.( )Unit 11 (5) Tools made of ordinary tool steel withstand heat much better than those made of high-speed steel.( ) (6) A taper key is used to remove the taper shank from the taper hole.Do not use anything but a taper key for this purpose.( ) 2Fill the blanks with the wo

21、rds given below:Socket, pocket, light duty, plain, spot facing, tapping, efficient, effective, holes, slots, less. (1) The end-cutting tool that is used to originate_in metal is called a“twist drill”.Unit 11 (2) The twist drill is very_tool. (3) The portion of the body next to the margin is of _diam

22、eter than the margin. (4) _is the operation of smoothing and squaring the surface around the end of a hole, as for the seat for a nut or the head of a cap screw. (5) The shank is the end of the drill which fits into the_ , spindle, or chuck of the drill press. (6) The Vertical Spindle Drilling machi

23、ne comes in three types: Heavy duty,_ ,and Sensitive.Unit 113Answer the following questions:(1) What steels are twist drills generally made of?(2) What are the principle part of a twist drill?(3) What is the margin?(4) Why is the body clearance made on a drill?(5) What is the shank of a drill?Unit 11READING MATERIALRadial Drilling Machine The radial drilling machine is designed for handling large work-pieces that cannot be easily movedThe drilling machine head is mounted on a heavy radial arm which may be from three to twelve or more feet longThis arm can be raised