铣削机械加工工艺工装夹具课程毕业设计外文文献翻译@中英文翻译@外文翻译

附录 A 英文原文 MILLING Milling is a machining process that is carried out by means of a multiedge tool known as a milling cutter .In this process,metal removal is achieved through combining the rotary motion of the milling cutter and linear motions of the workpiece simultaneously.Milling operations are employed in producing flat ,contoured and helical surfaces as well as for thread-and gear-cutting operations. Each of the cutting edges of a milling cutter acts as an individualsingle-point cutter when it engages with the workpiece metal .Therefore ,each of those cutting edges has appropriate rake and relief angles .Since only a few of the cutting edges are engaged with the workpiece at a time ,heavy cuts can be taken without adversely affecting the tool life .In fact ,the permissible cutting speeds and feeds for milling are there to four times higher than those for turning or drilling .Moreover,the quality of the surfaces machined by turning ,shaping ,or drilling. A wide variety of milling cutters is available in industry with the fact that a milling machine is a very versatile machine milling machine the backbone of a machining workshop. As far as the direction of cutter rotation and workpiece feed are concerned ,milling is performed by either of a machining workshop. Up milling (conventional milling) .In up milling the workpiece is fed against the direction of cutter rotation ,as shown in Fig.5. l(a) .As we can see in that figure ,the depth of cut (and consequently the load ) gradually increases on the successively engaged cutting edges .Therefore ,the machining process involves no impact loading ,thus ensuring smoother operation of the machine tool and longer tool life .The quality of the machined surface obtained by up milling is not very high .Nevertheless ,up milling is commonly used in inciustry ,especially for rough cuts. Down milling(climb milling) .As can be seen in Fig.5.1b ,in down milling the cutter rotation coincides with the direction of feed at the contact point between the tool and the workpiece .It can also be seen that the maximum depth of cut is achieved directly as the cutter engages with the workpiece .This result in a kind of impact ,or sudden loading .Therefore ,this method cannot be used the milling machine is equipped with a backlash eliminator on the feed screw. The advantages of this method include higher quality of the machined surface and easier clamping of workpieces,since the cutting forces act downward. Types of milling cutters There is wide variety of milling cutter shapes.Each of them is designed to perform effectively a specific.Generally,a milling cutter can be described as a multiedge cutting tool having the shape of a solid of revolution,with the cutting teeth arranged either on the periphery or on an end face or on both.following is a quick survery of the commonly used types of milling cutters. Plain milling cutter.A plain milling cutter is a disk-shaped cutting tool that may hace either straght or helical teeth,as shown in Fig.5.2a.This type is always mounted on horizental milling machines and is used for machining flat surfaces. Face milling cutters.A face milling cutter is also used for machining flat surfaces,it is bothed at the end of a shot arbor,which is in turn mounted on a vertical milling machine.Fig.5.2b indicates a milling cutter of this type. Plain metal slitting saw.Fig.5.2c indicates a plain metal slitting saw cutter.We can see that it actually involves a very thin plain milling cutter. Side milling cutter.Aside milling cutter is used for cutting slots,grooves,and splines.As we can see in Fig.5.2d,it is quite sililar to the plain milling cutter,the difference between the being that this type has teeth on the side .As was the case with the plain cutter ,the cutting teeth can be straight or helical. Angle milling cutter .An angle milling cutter is employed in cutting dovetail grooves ,ratchet wheels ,and the like .Fig.5.2e) indicates a milling cutter of this type. T-slot cutter .As shown in Fig.5.2f) ,a T-slot cutter involves a plain milling cutter with an integral shaft normal to it .As the name suggests ,this type is used for milling T-slots. End mill cutters .End mill cutters find common application in cutting slots ,grooves ,flutes ,splines ,pocketing work ,and the like .Fig.5.2g indicates an end mill cutter .The latter is always mounted on a vertical milling machine and can have two or four times ,which may be either straight or helical. Form milling cutters Th: teeh of a form milling cuuter have a certain shape ,which is identical to the metal to be removed during the milling operation. Examples of this type include gear currer ,gear hobs, convex and concave cutters, and the like .Form milling cutters are mounted on horizontal milling machines,as is esplained later when we discuss gear cutting. Material of Milling Cutters The commonly used milling cutters are made of high-speed steel, which is generally adequate for most jobs .Milling cutters tipped with sintered cabides nonferrous alloys as cutting teeth are usually employed for mass production,gh cutting speeds are requied.Cutting tool material may be classified in different ways main element. The main element may be carbon steel.high-speed steel meaJum-alloy steel .high-speed steel, a cemented carbide. Of course, iron is the main constitutent .of the first three. Carbon steel tools Carbon steel tools have a limited use, as they are characterized by. Low hot hardness and poor hardnability. Carbon contents range from o.s percent to 1.3 prcent. Tools of this type can be used for light work where temperatures produced do not exceed 204C. Medium-alloy steels These steels are not satisfactory for operations finishing operations. They can be used successfully. High-speed steels High-speed steel tools are characterized by superior wear resistance and hot hardness. High-speed steel tools contain Up to 18 percent tungsten and 51.5 percent chromium as the principal alloying element, Other alloying element such as molybdenum and cobalt give special qualities, These cutters will retain keen cutting edges at temperatures up to 593 C ( 1100F ) .Also the proper cutting fluids can increase their life and improve use to a considerable extent. Cast Alloys A number of nonferrous alloys know as stellhes have developed for use asculting tools ,these alloys usually contain 2 to 4 percent carbon 14 to 29 percent tungsten 27 to 32 percent chromium 40 to 50 percent cobalt; the tools must be used as cast ;and cannot ;be near treated, they are not affected by heat up to 815C (1500F), high-speed steel tools are somewhat harder that Stellite up to 537 C(ll00F).above this temperatures, stelite retails hardness much better ,highcutting speeds are possible with this type of tool than with high speed steel tools. Stelite, being cast ,has a tendency to shatter under shock ,thus ,it must be well supported in the toolhoider. It can be tip-brazed or weided to a shank steel. It may also be fashioned as a removable bit in a special toolhoider. Cemented Carbides Cemented carbide tools are know by trade named such as Carpoioy, Kennametal,Vascoioy-Ronet,and Firtnite. There are two genral grades of metal-cutting cemented in use: 1. The C grace is made up of tung-sten carbide with cobait grace is used in machining cast ircn and nonterrous metals. 2. The Sgrade is made up of tung-sten. Titanium,and tantalum carbides cobalt as a binder. This grade is used on steels withThe cobalt content may vary from 3 percent to 16 percent. The larger the amount of cobait. The tougher and more wear-resistant beccmes the tool. TheSgraces usually contain form 0 percent to 16 percent tianlum carbide and 0percent to 10 percent tantalum carbide. The mean grain size is important. Toolsof icential cnemical composition but of different grain size will have differentpropentes. Coarser grain materi tl is more snock resistant. Cemented carbices have the following cnaractenstics High naraness over a wide range of temperatures. High thermal concuctivity. Low thermal expansion. Stiffness. Cemented carbide shculd be used at much higher operating speeds than high speed steel tool. The depth of cut is the thickness of the meal layer that is to be removed in one cut o The maximum allowable depth of cue depends upon the material being machined and is commonly taken up to 5/16in. (or 8mm)in toughing operations and 1/16in(aboutl.5mm)in finishing operations .Another parameter that affects milling operations is the width of cut .The Latter is the width of the workpiece in contact with the cutter in a direction normal to the feed. We can easily see that the width of cut should decrease with increasingdepth of cut to keep the load and power requirement below by the cutter and the machine tool, respectively. Types of Milling Machines There are several types of milling machines in industry. They are generally classified based on their construction and design features .They vary from the common general-purpose types to duplicators and machining operation that involve a tool magazine and are capable of carrying out many machining operation with a single workpiece setup. For example Plain horizontal milling machine, Universal milling machine, Vertial milling machine, Duplicators,Machining centers. 附录 B 汉语翻译 铣 削 铣削是用铣刀进行多刃旋转加工的工艺。在这种工艺中，金属的切除是通过铣刀的旋转运动以及此同时工件的直线运动的组合来实现。铣削加工可用于生成平面、曲面和螺旋面，也用于螺纹和切齿加工。 当与工件金属啮 合切入时，铣刀的每个刀刃相当于单刃刀片，因此，每个单刃片有一定的前角和后角，因为只有切削刃的一小部分与工件在同一时间接触，所以大切削量不会严重影响刀具的寿命。事实上，铣削加工的切削量与进给量比车和钻加工高出到 4倍。并且铣削加工的工件表面质量通常高于那些被车，刨和钻的工件表面质量。 在工业上各种各样的铣刀得到了广泛的运用。这也与事实一致，铣削加工是个通用性极强的加工工具，也使得铣床成为工厂机加车间的生产主干。 根据刀具的旋转方向与工件的进给方向，铣削以下两种工件方式。 逆铣 (常规铣削 )，工件的进给方向是与旋转 方向相反，如外文资料中图 5 1a 所示，当连续的与切削相触时，切削深度逐渐增大。因此，机加过程可以保证平稳的操纵与更长的刀具寿命。逆铣加工的工件表面质量一般不是太高。虽然如此，逆铣还是在工业中普遍被使用，特别是在粗加工中。 顺铣。如外文资料中图 5 1b 所示，顺铣时，在刀具和工件接触时可以看作直接获得最大的切削深度。这将是一种影响，或者是突然加载。因此，除非铣床加装了齿隙消除装置在进给丝杆上，要不这种方法决不能被使用。此种方法的好处包括较高质量的加工表面，较容易的装卡工件。因为切削力是向下的。 铣刀的类型 铣刀 的形状多种多样。它们中的每一个都为进行有效的特殊铣削操作面设计。通常铣刀被称为多刃刀具，其形状为旋转体，切削刃做在旋转体的周边上式端面上，或者周边和端面上均有。下面是常用铣刀的一个快速概括。 普通铣刀，普遍铣刀是一碟状物的切削工具，其分为直齿与螺旋齿。如图外文资料中 5 2a 所示。这种铣刀通常固定在卧铣床上并且用于表面的平面加工。 平面铣刀。平面铣刀也用于表面的平面加工，它被固定在矩轴的末端，这样可以逐次安装到立式铣床上。外文资料中图 5 2b 显示了此种铣刀。 锯片铣刀。外文资料中图 5 2c 给出了一个普通金属切 割的锯片。我们可以看出确实为十分薄化的普通铣刀。 侧面铣刀。侧面铣刀被用作槽和键槽之类的加工。我们可以参看外文资料中图 5 2d它与普通铣刀十分相似，所不同的是此种铣刀的齿是在边上。由于和普通铣刀很象，切割齿也有直齿和螺旋齿。 角铣刀。角铣刀用于燕尾槽，棘轮的加工。外文资料中图 5 2e 给出了此种类型的铣刀。 T 形铣刀。如外文资料中图 5 2f 所示。 T 形铣刀是普通铣刀刀盘加上整轴而成，并彼此垂直，正如其名子，这种铣刀被用作铣丁形口。 端铣刀。端铣刀通常用于开口、开槽、出屑槽、键槽，内腔的加工，如图 5 2g 所示。其 末端通常安装在立式铣床上并有两到四个出屑槽，其也有直与螺旋之分。 成形铣刀。成形铣刀的齿有特定的形状，这个形状与铣削时要切削的那部分金属形状一致。其典型的包括：齿轮铣刀、齿轮滚刀、凹方与凸方刀和及其类似的。成形铣刀被安装在