外文翻译切削刀具

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 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 without 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 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 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 DRILLA center 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 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 hole 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 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 when 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 1/2for holes greater than 1/2stock of less than 0.0150 on diameterstock 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. Many 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 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, feedrate (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, 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 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 for a specific tap. For 75% effective threads the formula that will determine the correct drill size is: D 1/N, whereD = 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 cutting 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 compensation (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 and have the machine cut the same part features as with the end mill originally programmed for that tool path. BULL END MILLA 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 size 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 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 MILLA ball end mill is a bull end mill where the corner radius is exactly 1/2 the tools diameter. This gives the tool a spherical 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 roll over a surface, a ball end mill can be used to cut any such surface. INSERT END MILLAn 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 large 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 to 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, 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 compute 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 required 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 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 cut, 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 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, 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 cutting 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. Then 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 damage 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 materials 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 coating 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 harder. 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 work 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 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-flute 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 soft, gummy materials such as aluminum and copper. Four-flute end mills are recommended for harder, tougher steel materials. 中文译文切削刀具在选择切削刀具时，首先应考虑需要执行的操作。这里简单介绍了铣削操作中最常用的基本刀具。钻头钻头用于在工件上加工圆柱形孔。钻孔可以是通孔或者盲孔。盲孔是指没有完全贯穿工件的孔。通常，工程图纸上都会规定某个钻孔需要钻至“外径深度”。这表示孔径必须为规定深度，不考虑钻头的斜角头部。在测量刀具长度偏移时，所测量的是钻头及其头部的长度。那么钻孔的深度应该达到多少才能获得正确的外径深度？您需要知道钻尖的长度。提示：钻尖的长度取决于刀锋角以及钻头直径。钻头直径乘以某个常量即可得到钻尖的长度；常量的值取决于钻尖角度（大多数标准高速钢钻头的钻尖角为118度）。对于钻尖角为：118度135度141度钻头直径乘以：0.3 0.207 0.177 使用这些常量可计算钻尖长度，误差只有千分之几英寸。中心钻中心钻是一种小型钻头，配有引导点。用于加工小径孔，孔壁带有锥度。 如果孔的位置必须保持较小公差，应首先使用中心钻，然后使用麻花钻光整孔。中心钻孔锥形壁面可保持麻花钻在开始钻入工件时对正。 提示：许多机床都使用这种经验方法：如果中心钻孔的直径公差不重要，应尽可能增加钻孔深度。在0.375英寸直径以下，使用标准60度中心钻孔加工的孔径将接近钻孔深度。对于较大的中心钻 0.375英寸或者更大深度与直径比例更大，因此偏差可能达到0.080至0.100英寸。扩孔钻扩孔钻用于去除钻孔中的少量材料。扩孔钻可使孔径公差达到极小范围，并可获得极高的表面质量。首先应钻孔，在孔壁面保留0.005至0.015英寸余量，然后由扩孔钻清除。提示：在扩孔时，孔的尺寸以及位置精度的最佳状态是按照下列步骤操作：首先钻孔，然后镗孔，最后扩孔。提示：扩孔的余量取决于孔径。一般情况下：对于孔径小于1/2的孔对于孔径大于1/2的孔直径余量低于0.0150直径余量0.030工件材料的类型以及孔的加工方法都会影响加工余量。提示：在使用G85 (镗入，镗出) 固定循环进出扩孔钻时，可加工出精度最高，最均匀的表面。许多人都试图使用G81 (钻孔)固定循环节省时间，该循环将刀送入后，快速退出。其加工速度超过G85，但通常会在孔的圆柱形表面上产生螺旋痕迹。尽管这种痕迹非常轻微，而且不会影响孔的尺寸，但某些客户会因为孔的外观而拒绝接受。丝锥丝锥用于在钻孔内加工螺纹。注：在使用铣床攻丝时必须特别小心。提示：如果您使用可执行刚性攻丝的机床，进给速度（英寸每分）螺距转/分。此外，攻丝尺寸不得超过1.5 x丝锥的外径。如果接触长度超过紧固件直径的1.5倍，螺纹连接的强度将不再增加。如果您需要增加螺纹深度，首先使用机床攻丝，然后手动攻丝至最终深度。如果深度超过1.5 x孔径，丝锥断裂的可能性会大大增加。切屑控制较为困难。在盲孔攻丝时，必须尽可能钻至最大深度，以免在丝锥下方挤压切屑。使用螺旋槽丝锥可将切屑带出螺纹孔。为了进一步减少攻丝的困难，应确保所有需要攻丝的孔内没有切屑，并使用专用于所加工材料的攻丝液。提示：螺孔钻尺寸为特定丝锥规定的孔径。对于75%有效螺纹而言，用于确定正确钻孔尺寸的公式为：D 1/N，其中D = 丝锥外径N = 每英寸的螺纹圈数75%螺纹深度的螺纹孔，强度只比100%螺纹深度的螺纹孔低5，且切削力只需1/3。端铣刀端铣刀的形状类似于钻头，但底部平坦。主要使用刀具侧面切削，加工工件的轮廓。提示：在使用刀具补偿功能（G41 以及 G42）编程，使用端铣刀切削轮廓或者型腔刀具轨迹时，在调节加工部位尺寸时非常灵活。使用刀具补偿功能可调节原料的切削量。端铣刀磨损时，少量偏移调节可确保每一个部件都有相同的尺寸。您还可使用不同尺寸的刀头，让机床沿着原来设置的刀具路径切削出相同的部件尺寸。圆鼻端铣刀圆鼻端铣刀与普通的端铣刀相同，但在凹槽与端铣刀底部相交的弯角处有一半径。该半径最大可达到刀具直径的一半。提示：圆鼻端铣刀在加工壁面与底面之间的圆角时非常有效。而且可提高端铣刀的强度。在加工硬质材料时，标准端铣刀的尖角容易碎裂，而且磨损速度比圆鼻端铣刀更快。圆鼻端铣刀的半径在切入工件时更为缓和。球铣刀球铣刀是一种圆角半径正好等于刀具直径一半的圆鼻端铣刀。这使得刀尖的形状正好为球形。还可像端铣刀一样用刀具的侧面切削。提示：球铣刀的主要用途是加工放样曲面。刀具的球形轮廓能够沿着任何起伏表面移动，并可沿着刀具的“球状末端”切削任何位置。由于球能够在表面上滚动，因此球铣刀可用于切削任何此类表面。嵌齿端铣刀嵌齿端铣刀与标准端铣刀相同，但配有可更换的硬质合金刀片。提示：嵌齿端铣刀用于在更高速度下切削硬质合金之外的金属。这种刀具的直径范围很广，能够实现更大深度的切削。这一点非常有用，但在使用这些刀具时，最好计算切削所需的功率。在哈斯控制设备上，这只是小菜一碟：在前面板上有一个按钮标有“HELP/CALC”。按下该按钮可打开帮助菜单，再次按下可打开计算器功能。使用PAGE UP/PAGE DOWN按键可在下列三个页面之间滚动：三角学帮助，圆形内插帮助，以及铣削帮助。每一个页面在左上角都有一个简单的计算器。在铣削帮助页面上，可求解三个方程：1. SFM = (刀具直径英寸) * RPM * 3.14159 / 122. (切屑载荷英寸) = (进给速度英寸/分) / RPM / 槽数3. (进给速度英寸/分) = RPM / (螺距)在使用这三个方程时，您可输入已知参数，控制设备将计算剩余的未知数。在计算切削所需功率时，必须输入RPM，进给速度，槽数，切削深度，切削宽度并从菜单中选择某一材料。如果更改上面的任一数值，计算器都会自动更新切削所需功率。选择刀具时下一步需要考虑的是切削的材料。在金属加工行业中最常见的切削材料可分为两类：不含铁与含铁材料。不含铁材料包括铝和铝合金、铜和铜合金、镁合金、镍与镍合金、钛与钛合金。普通的含铁材料包括碳钢、合金钢、不锈钢、工具钢，以及含铁铸造材料例如铸铁。不含铁金属比较软，容易切削，但镍与钛除外。含铁金属通常较硬，难于切削。在选择刀具时，刀具材料是最重要的考虑因素。大部分上述刀具都可提供三种基本材料：高速钢、整体硬质合金以及硬质合金嵌齿。几乎所有这些基本刀具材料都可用于切削各种材料。区别只在性能。高速钢刀具的硬度非常高，但耐磨性较差。硬质合金的耐磨性非常好，但容易碎裂。硬质合金适合在较高转速和进给速度下切削材料，但价格更贵。硬质合金嵌齿刀具非常适合大批量生产场合，因为每一个嵌齿上都有多个切削边。某个切削边磨损后，您可分度至另一个切削边，在所有切削边都已用过之后，只需更换嵌齿，而非整个刀具。提示：如果您正在使用高速钢钻头，必须首先使用中心钻。然后再钻孔。这可确保钻孔的正确位置。如果你正在使用硬质合金砖头，没有必要首先使用中心钻，因为硬质合金转头配有自行对中的刀尖。如果使用硬质合金钻头钻削已经执行中心钻加工的孔，会损坏钻头。外切削边缘会在钻头开始切削之前接触锥形壁面。这会对外切削边造成冲击，并导致钻头碎裂。硬质合金钻头必须首先从刀尖开始切削，然后再使用外切削边。这些刀具材料都可提供各种不同的涂层以提高其性能。目前最常用的三种涂层材料为氮化钛 (TiN)，, 碳氮化钛 (TiCN)，以及氮化铝钛(TiAlN)。TiN涂层的金色非常容易识别。TiN涂层的优点是表面硬度更高、刀具使用寿命更长、耐磨性更好、润滑性更佳，可减少摩擦，并降低边缘积聚。TiN涂层主要用于加工低合金钢和不锈钢。TiCN涂层与TiN相比颜色为灰色，硬度更高。其优点在于切削速度和进给速度更高(与TiN相比可提高40% 至60%)，金属切除速度更快，而且具有极佳的耐磨性能。TiCN涂层可加工所有材料。TiAlN涂层呈现灰色和黑色，主要用于加工硬质合金。适合非常高的加工温度，最高可达800，这是其非常适合不使用冷却剂的高速加工场合。推荐使用压缩空气清除切削区域的切屑。这种刀具非常适合硬质钢、钛以及镍合金，包括铸铁以及高硅铝之类的磨蚀性材料。在选择端铣刀时，凹槽数或切削边数是一个重要因素。端铣刀的槽越多，槽的尺寸越小或者越窄。双槽端铣刀的中心实心部分大约为端铣刀直径的52。三槽端铣刀的中心部分为直径的56%，四槽或者槽数更多的端铣刀的中心部分为直径的61%。这表示端铣刀的槽数越多，切削中的刚性就越高。建议两槽端铣刀用于较软的粘性材料，例如铝和铜。建议四槽端铣刀用于较硬的钢材。