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1、英文原文 CUTTING TOOLS When selecting cutting tools for a job, the first thing to consider is what type of operation needs to be performed. Here is a quick description of the basic cutting tools most often used in milling operations. DRILL A drill is used to create a round, cylindrical

2、hole in a workpiece. Drilled holes can be "through holes" or "blind holes". A "blind hole" is not cut entirely through a workpiece. Quite often, an engineering blueprint will specify a drilled hole to be drilled to "full diameter depth." This means that the hole diameter must be a specified depth wi

3、thout regard to the angled tip of the drill. When you measure your tool length offset, you are measuring the length of the drill and its tip. So how deep do you drill the hole so that the full diameter depth is correct? Well, you need to know how long the drill point is. TIP: The length of the

4、 drill point is determined by the tool point angle and the drill diameter. You can calculate the length of the drill point by multiplying the drill diameter by a constant; the value of the constant depends on the drill point angle (most standard high-speed steel drills have a tool point angle of 118

5、 degrees). For a drill point angle of: 118 degrees 135 degrees 141 degrees Multiply the drill diameter by: 0.3 0.207 0.177 Using these constants allows you to calculate the drill point length within a few thousandths of an inch. CENTER DRILL A cen

6、ter drill is a small drill with a pilot point. It is used to create a small hole with tapered walls. When a holes location must be held to a close tolerance, use a center drill first and then use a twist drill to finish the hole. The tapered walls of the center-drilled hole will keep the twist drill

7、 straight when it begins to drill into the workpiece. TIP: Many machinists use this rule of thumb: If the tolerance of the diameter of a center-drilled hole is not critical, drill as deep as you want this diameter to be. With a standard, 60-degree center drill below 0.375-inch diameter, the hol

8、e diameter produced will be close to the depth you drilled. With larger center drills – 0.375 inch and above – the depth-to-diameter ratio becomes larger, so you could be off by as much as 0.080 to 0.100 inch. REAMER A reamer is designed to remove a small amount of material from a drilled

9、hole. The reamer can hold very close tolerance on the diameter of a hole, and give a superior surface finish. The hole must be drilled first, leaving 0.005 to 0.015 inch of stock on the walls of the hole for the reamer to remove. TIP: The ideal situation for hole size accuracy and location whe

10、n reaming is to process the hole with the following steps: the hole is first drilled, then bored, then reamed. TIP: Stock allowance for a reamed hole will depend on the size of the hole. A general rule is: for holes less than 1/2" for holes greater than 1/2" stock of less than 0.0150" on di

11、ameter stock of 0.030" on diameter The type of workpiece material and the method used to create the hole will affect the stock allowance. TIP: A reamer produces the best, most uniform surface finish when it is fed into and out of the hole using the G85 (bore in, bore out) canned cycle. Ma

12、ny people try to save time by using the G81 (drill) canned cycle, which will feed into a hole and rapid out. It is quicker than G85, but will usually leave a helical swirl mark on the cylindrical surface of the hole. Although this swirl mark is only a cosmetic flaw and doesnt affect the size of the

13、hole, the appearance of the hole may be rejected by some customers. TAP A tap is used to create screw threads inside of a drilled hole. NOTE: Great care must be taken when using a milling machine to perform a tapping operation. TIP: If you are using a machine with rigid tapping, fe

14、edrate (in inches per minute) = thread pitch x revolutions per minute. Also, you should never tap more than 1.5 x the taps major diameter. Threaded connections will not increase in strength if the contact length is more than 1.5 times the diameter of the fastener. If you need threads that are deeper

15、, machine tap them first and hand-tap them to finished depth. If you tap deeper than 1.5 x the hole diameter, your chances of breaking the tap increase dramatically. Chip control becomes a problem. When tapping blind holes, always drill as deep as possible to avoid packing chips below the tap. Using

16、 a spiral flute tap will bring the chips up, out of the hole. To further reduce tapping headaches, make sure all holes to be tapped are free of chips, and use a tapping fluid specifically designed for the type of material you are cutting. TIP: Tap drill size is the size of the hole required fo

17、r a specific tap. For 75% effective threads the formula that will determine the correct drill size is: D – 1/N, where D = major diameter of the tap and N = number of threads per inch A tapped hole with 75% of thread depth has only 5% less strength than 100% thread and takes only 1/3 of the cu

18、tting force of a 100% thread. END MILL An end mill is shaped similar to a drill, but with a flat bottom. It is used primarily to cut with the side of the tool to contour the shape of a workpiece. TIP: Programming an end mill to cut contour or pocket tool paths using cutter compensat

19、ion (G41 and G42) allows you much more flexibility in adjusting the size of machined features. Using cutter compensation allows you to adjust the amount of stock removal. As an end mill wears, minor offset adjustments allow you to make every part the same size. You may also use a different size end

20、and have the machine cut the same part features as with the end mill originally programmed for that tool path. BULL END MILL A bull end mill is the same as a regular end mill except that there is a radius on the corner where the flutes meet the bottom of the end mill. This radius can be any s

21、ize up to one-half of the tools diameter. TIP: Bull end mills are effective for producing a corner radius between a wall and a floor on a given part feature. They also add to the strength of an end mill. When machining hard, tough to cut materials, the sharp corners on a standard end mill tend

22、 to chip and wear faster than an end mill with a corner radius. The radius on a bull end mill provides a more gradual shearing entry in to the work piece. BALL END MILL A ball end mill is a bull end mill where the corner radius is exactly 1/2 the tools diameter. This gives the tool a spherica

23、l shape at the tip. It can be used to cut with side of the tool like an end mill. TIP: The primary purpose of a ball end mill is to machine lofted surfaces. The spherical shape of the tool is able to move along any undulating surface and cut anywhere along the cutters "ball end." As a ball can

24、 roll over a surface, a ball end mill can be used to cut any such surface. INSERT END MILL An insert end mill is the same as a standard end mill but with replaceable carbide inserts. TIP: Insert end mills are designed to remove metal at higher rates than solid carbide. They come in a la

25、rge range of diameters and are able to cut at a deeper depth of cut. This is fantastic but, when using these cutters, it is a good idea to calculate the horsepower required to make a cut. Piece of cake on your Haas control: There is a button on the front labeled "HELP/CALC." Press this button once t

26、o get the Help menu, press it again to get the Calculator functions. Use the PAGE UP/PAGE DOWN keys to scroll between three pages: Trigonometry Help, Circular Interpolation Help, and Milling Help. Each one of these pages has a simple calculator in the upper left hand corner. On the Milling Help page

27、, you can solve three equations: 1. SFM = (cutter diameter [in.]) * RPM * 3.14159 / 12 2. (Chip load [in.]) = (feed [in. per min.]) / RPM / # of flutes 3. (Feed [in. per min.]) = RPM / (thread pitch) With all three equations, you may enter all but one of the values and the control will co

28、mpute and display the remaining value. To calculate the horsepower required for a cut, you must enter values for RPM, feed rate, number of flutes, depth of cut, width of cut, and choose a material from the menu. If you change any of the above values, the calculator will automatically update the requ

29、ired horsepower for the cut you intend. The next thing to consider when choosing cutting tools for a job is what material you are going to cut. The most common materials cut in the metalworking industry can be divided into two categories: non-ferrous and ferrous. Non-ferrous materials include

30、aluminum and aluminum alloys, copper and copper alloys, magnesium alloys, nickel and nickel alloys, titanium and titanium alloys. Common ferrous materials include carbon steel, alloy steel, stainless steel, tool steel, and ferrous cast metals like iron. Non-ferrous metals are softer and easier to cu

31、t, with the exception of nickel and titanium. Ferrous metals, on the other hand, are generally harder in composition and tougher to cut. Cutting tool material is one of the biggest decisions youll have to make when choosing a cutting tool. Most all of the cutters described above are available

32、in three basic materials: high-speed steel, solid carbide, and carbide insert style. Almost all of the basic cutting tool materials can be used to cut almost all materials. It really boils down to performance. High-speed steel cutting tools have very high toughness but lack wear resistance. Carbide,

33、 on the other hand, has a very high wear resistance but chips and breaks easily. Carbide will always be able to cut materials at higher speeds and feeds, but is more expensive. Carbide insert cutting tools are very useful in high-production situations because the inserts are designed with multiple c

34、utting edges on each insert. When they become worn out, you index the inserts to the next cutting edge, and when all cutting edges are used, you only replace the inserts and not the whole tool. TIP: If you are using a high-speed steel drill, always use a center drill to get the hole started. T

35、hen drill the hole. This will ensure that the drilled hole is in the correct location. If you are using a carbide drill, it is not necessary to center drill first because carbide drills are ground with a self-centering tip. Using a carbide drill to drill a hole that is already center drilled will da

36、mage the drill. The outer cutting edges will contact the tapered walls before the tip of the drill begins to cut. This will shock the outer cutting edges and cause the drill to chip. Carbide drills must begin to cut at the tip before the outer cutting edges. Each one of these cutting tool mate

37、rials is available with a variety of different coatings to enhance their performance. The three coatings most widely use today are titanium nitride (TiN), titanium carbonitride (TiCN), and titanium aluminum nitride (TiAlN). TiN coating is easily recognized by its gold color. The advantages of TiN co

38、ating are increased surface hardness, increased tool life, better wear resistance and higher lubricity, which decreases friction and reduces edge build-up. TiN coating is mostly recommended for machining low alloy steel and stainless steel. TiCN coating is gray colored compared to TiN, and even hard

39、er. Its advantages are increased cutting speed and feeds (40% to 60% higher compared to TiN), higher metal removal rates, and superior wear resistance. TiCN coatings are recommended for machining all material types. TiAlN coating appears gray or black and is primarily used to coat carbide. It can wo

40、rk at very high temperatures, up to 800 degrees Celsius, which makes it ideal for high-speed machining without coolant. Pressurized air is recommended to remove chips from the cutting zone. It works well on hardened steels, titanium and nickel alloys, as well as abrasive materials like cast iron and

41、 high silicon aluminum. When selecting end mill tools, the number of flutes, or cutting edges, is an important factor. The more flutes an end mill has, the smaller, or shallower, the flutes are. The solid center section of an end mill is approximately 52% of the end mills diameter on a two-flu

42、te end mill. The center section of a three-flute end mill is 56% of its diameter, and an end mill with four or more flutes has a center section that is 61% of its diameter. This means that the more flutes an end mill has, the more rigid it will be in the cut. Two-flute end mills are recommended for

43、soft, gummy materials such as aluminum and copper. Four-flute end mills are recommended for harder, tougher steel materials. 中文譯文 切削刀具 在選擇切削刀具時，首先應考慮需要執(zhí)行的操作。這里簡單介紹了銑削操作中最常用的基本刀具。 鉆頭 鉆頭用于在工件上加工圓柱形孔。鉆孔可以是通孔或者盲孔。盲孔是指沒有完全貫穿工件的孔。通常，工程圖紙上都會規(guī)定某個鉆孔需要鉆至“外徑深度”。這表示孔徑必須為規(guī)定深度，不考慮鉆頭的斜角頭部。在測量刀具長度偏移時，所測量的

44、是鉆頭及其頭部的長度。那么鉆孔的深度應該達到多少才能獲得正確的外徑深度？您需要知道鉆尖的長度。 提示：鉆尖的長度取決于刀鋒角以及鉆頭直徑。鉆頭直徑乘以某個常量即可得到鉆尖的長度；常量的值取決于鉆尖角度（大多數(shù)標準高速鋼鉆頭的鉆尖角為118度）。 對于鉆尖角為： 118度 135度 141度 鉆頭直徑乘以： 0.3 0.207 0.177 使用這些常量可計算鉆尖長度，誤差只有千分之幾英寸。 中心鉆 中心鉆是一種小型鉆頭，配有引導點。用于加工小徑孔，孔壁帶有錐度。 如果孔的位置必須保持較小公差，應首先使用中心鉆，然后使用麻花鉆光整孔。中心鉆孔錐形壁面可保持麻

45、花鉆在開始鉆入工件時對正。 提示：許多機床都使用這種經(jīng)驗方法：如果中心鉆孔的直徑公差不重要，應盡可能增加鉆孔深度。在0.375英寸直徑以下，使用標準60度中心鉆孔加工的孔徑將接近鉆孔深度。對于較大的中心鉆 0.375英寸或者更大深度與直徑比例更大，因此偏差可能達到0.080至0.100英寸。 擴孔鉆 擴孔鉆用于去除鉆孔中的少量材料。擴孔鉆可使孔徑公差達到極小范圍，并可獲得極高的表面質(zhì)量。首先應鉆孔，在孔壁面保留0.005至0.015英寸余量，然后由擴孔鉆清除。 提示：在擴孔時，孔的尺寸以及位置精度的最佳狀態(tài)是按照下列步驟操作：首先鉆孔，然后鏜孔，最后擴孔。 提示：擴孔的余量

46、取決于孔徑。一般情況下： 對于孔徑小于1/2"的孔 對于孔徑大于1/2"的孔 直徑余量低于0.0150" 直徑余量0.030" 工件材料的類型以及孔的加工方法都會影響加工余量。 提示：在使用G85 (鏜入，鏜出) 固定循環(huán)進出擴孔鉆時，可加工出精度最高，最均勻的表面。許多人都試圖使用G81 (鉆孔)固定循環(huán)節(jié)省時間，該循環(huán)將刀送入后，快速退出。其加工速度超過G85，但通常會在孔的圓柱形表面上產(chǎn)生螺旋痕跡。盡管這種痕跡非常輕微，而且不會影響孔的尺寸，但某些客戶會因為孔的外觀而拒絕接受。 絲錐 絲錐用于在鉆孔內(nèi)加工螺紋。 注：在使用銑床攻絲時必須特別小心。 提示：如果您使用可

47、執(zhí)行剛性攻絲的機床，進給速度（英寸每分）＝螺距轉/分。此外，攻絲尺寸不得超過1.5 x絲錐的外徑。如果接觸長度超過緊固件直徑的1.5倍，螺紋連接的強度將不再增加。如果您需要增加螺紋深度，首先使用機床攻絲，然后手動攻絲至最終深度。如果深度超過1.5 x孔徑，絲錐斷裂的可能性會大大增加。切屑控制較為困難。在盲孔攻絲時，必須盡可能鉆至最大深度，以免在絲錐下方擠壓切屑。使用螺旋槽絲錐可將切屑帶出螺紋孔。為了進一步減少攻絲的困難，應確保所有需要攻絲的孔內(nèi)沒有切屑，并使用專用于所加工材料的攻絲液。 提示：螺孔鉆尺寸為特定絲錐規(guī)定的孔徑。對于75%有效螺紋而言，用于確定正確鉆孔尺寸的公式為： D – 1

48、/N，其中 D = 絲錐外徑 N = 每英寸的螺紋圈數(shù) 75%螺紋深度的螺紋孔，強度只比100%螺紋深度的螺紋孔低5％，且切削力只需1/3。 端銑刀 端銑刀的形狀類似于鉆頭，但底部平坦。主要使用刀具側面切削，加工工件的輪廓。 提示：在使用刀具補償功能（G41 以及 G42）編程，使用端銑刀切削輪廓或者型腔刀具軌跡時，在調(diào)節(jié)加工部位尺寸時非常靈活。使用刀具補償功能可調(diào)節(jié)原料的切削量。端銑刀磨損時，少量偏移調(diào)節(jié)可確保每一個部件都有相同的尺寸。您還可使用不同尺寸的刀頭，讓機床沿著原來設置的刀具路徑切削出相同的部件尺寸。 圓鼻端銑刀 圓鼻端銑刀與普通的端銑刀相同，但在凹槽與端銑刀底部相

49、交的彎角處有一半徑。該半徑最大可達到刀具直徑的一半。 提示：圓鼻端銑刀在加工壁面與底面之間的圓角時非常有效。而且可提高端銑刀的強度。在加工硬質(zhì)材料時，標準端銑刀的尖角容易碎裂，而且磨損速度比圓鼻端銑刀更快。圓鼻端銑刀的半徑在切入工件時更為緩和。 球銑刀 球銑刀是一種圓角半徑正好等于刀具直徑一半的圓鼻端銑刀。這使得刀尖的形狀正好為球形。還可像端銑刀一樣用刀具的側面切削。 提示：球銑刀的主要用途是加工放樣曲面。刀具的球形輪廓能夠沿著任何起伏表面移動，并可沿著刀具的“球狀末端”切削任何位置。由于球能夠在表面上滾動，因此球銑刀可用于切削任何此類表面。 嵌齒端銑刀 嵌齒端銑刀與標準端銑刀相同

50、，但配有可更換的硬質(zhì)合金刀片。 提示：嵌齒端銑刀用于在更高速度下切削硬質(zhì)合金之外的金屬。這種刀具的直徑范圍很廣，能夠實現(xiàn)更大深度的切削。這一點非常有用，但在使用這些刀具時，最好計算切削所需的功率。在哈斯控制設備上，這只是小菜一碟：在前面板上有一個按鈕標有“HELP/CALC”。按下該按鈕可打開幫助菜單，再次按下可打開計算器功能。使用PAGE UP/PAGE DOWN按鍵可在下列三個頁面之間滾動：三角學幫助，圓形內(nèi)插幫助，以及銑削幫助。每一個頁面在左上角都有一個簡單的計算器。在銑削幫助頁面上，可求解三個方程： 1. SFM = (刀具直徑[英寸]) * RPM * 3.14159 / 12

51、 2. (切屑載荷[英寸]) = (進給速度[英寸/分]) / RPM / 槽數(shù) 3. (進給速度[英寸/分]) = RPM / (螺距) 在使用這三個方程時，您可輸入已知參數(shù)，控制設備將計算剩余的未知數(shù)。在計算切削所需功率時，必須輸入RPM，進給速度，槽數(shù)，切削深度，切削寬度并從菜單中選擇某一材料。如果更改上面的任一數(shù)值，計算器都會自動更新切削所需功率。 選擇刀具時下一步需要考慮的是切削的材料。在金屬加工行業(yè)中最常見的切削材料可分為兩類：不含鐵與含鐵材料。不含鐵材料包括鋁和鋁合金、銅和銅合金、鎂合金、鎳與鎳合金、鈦與鈦合金。普通的含鐵材料包括碳鋼、合金鋼、不銹鋼、工具鋼，以及含鐵鑄造材

52、料例如鑄鐵。不含鐵金屬比較軟，容易切削，但鎳與鈦除外。含鐵金屬通常較硬，難于切削。 在選擇刀具時，刀具材料是最重要的考慮因素。大部分上述刀具都可提供三種基本材料：高速鋼、整體硬質(zhì)合金以及硬質(zhì)合金嵌齒。幾乎所有這些基本刀具材料都可用于切削各種材料。區(qū)別只在性能。高速鋼刀具的硬度非常高，但耐磨性較差。硬質(zhì)合金的耐磨性非常好，但容易碎裂。硬質(zhì)合金適合在較高轉速和進給速度下切削材料，但價格更貴。硬質(zhì)合金嵌齒刀具非常適合大批量生產(chǎn)場合，因為每一個嵌齒上都有多個切削邊。某個切削邊磨損后，您可分度至另一個切削邊，在所有切削邊都已用過之后，只需更換嵌齒，而非整個刀具。 提示：如果您正在使用高速鋼鉆頭，必須

53、首先使用中心鉆。然后再鉆孔。這可確保鉆孔的正確位置。如果你正在使用硬質(zhì)合金磚頭，沒有必要首先使用中心鉆，因為硬質(zhì)合金轉頭配有自行對中的刀尖。如果使用硬質(zhì)合金鉆頭鉆削已經(jīng)執(zhí)行中心鉆加工的孔，會損壞鉆頭。外切削邊緣會在鉆頭開始切削之前接觸錐形壁面。這會對外切削邊造成沖擊，并導致鉆頭碎裂。硬質(zhì)合金鉆頭必須首先從刀尖開始切削，然后再使用外切削邊。 這些刀具材料都可提供各種不同的涂層以提高其性能。目前最常用的三種涂層材料為氮化鈦 (TiN)，, 碳氮化鈦 (TiCN)，以及氮化鋁鈦(TiAlN)。TiN涂層的金色非常容易識別。TiN涂層的優(yōu)點是表面硬度更高、刀具使用壽命更長、耐磨性更好、潤滑性更佳，

54、可減少摩擦，并降低邊緣積聚。TiN涂層主要用于加工低合金鋼和不銹鋼。TiCN涂層與TiN相比顏色為灰色，硬度更高。其優(yōu)點在于切削速度和進給速度更高(與TiN相比可提高40% 至60%)，金屬切除速度更快，而且具有極佳的耐磨性能。TiCN涂層可加工所有材料。TiAlN涂層呈現(xiàn)灰色和黑色，主要用于加工硬質(zhì)合金。適合非常高的加工溫度，最高可達800℃，這是其非常適合不使用冷卻劑的高速加工場合。推薦使用壓縮空氣清除切削區(qū)域的切屑。這種刀具非常適合硬質(zhì)鋼、鈦以及鎳合金，包括鑄鐵以及高硅鋁之類的磨蝕性材料。 在選擇端銑刀時，凹槽數(shù)或切削邊數(shù)是一個重要因素。端銑刀的槽越多，槽的尺寸越小或者越窄。雙槽端銑刀的中心實心部分大約為端銑刀直徑的52％。三槽端銑刀的中心部分為直徑的56%，四槽或者槽數(shù)更多的端銑刀的中心部分為直徑的61%。這表示端銑刀的槽數(shù)越多，切削中的剛性就越高。建議兩槽端銑刀用于較軟的粘性材料，例如鋁和銅。建議四槽端銑刀用于較硬的鋼材。