行业新闻

当前位置:网站首页 > 新闻中心 > 行业新闻

  • 机械加工的方法及适用范围
  • 本站编辑:杭州宇晨机械有限公司发布日期:2019-11-18 21:06 浏览次数:
机械加工中,根据机械加工工件的材质和要求可以选择不同的加工方法,了解常见的机械加工类型及机械加工知识,可以让我们选择更合适的机械加工方法及适用范围,那么机械加工方法和适用范围应该怎么选择呢?
 
 
一、车削加工
 
利用车床加工零件的方法统称为车削加工。车削加工中以工件旋转,形成主切削运动。刀具沿平行旋转轴线运动时,就形成内、外圆柱面。刀具沿与轴线相交的斜线运动,就形成锥面。仿形车床或数控车床上,可以控制刀具沿着一条曲线进给,则形成一特定的旋转曲面。采用成型车刀,横向进给时,也可加工出旋转曲面来。车削加工还可以加工螺纹面、端平面及偏心轴等。车削加工精度一般为IT11—IT6,表面粗糙度为12.5—0.8μm。精车时,可达IT6—IT5,粗糙度可达0.4—0.1μm。车削加工的生产率较高,切削过程比较平稳,刀具较简单。
 
适用范围:钻中心孔、钻孔、铰孔、攻螺纹、车外圆、镗孔、车端面、车槽、车成形面、车锥面、滚花、车螺纹
 
二、铣削加工
 
铣削加工是在铣床上使用旋转多刃刀具(铣刀)对工件进行加工的方法,主切削运动是刀具的旋转。卧铣时,平面的形成是由铣刀的外圆面上的刃形成的。立铣时,平面是由铣刀的端面刃形成的。提高铣刀的转速可以获得较高的切削速度,从而可以生产率较高。但由于铣刀刀齿的切入、切出,形成冲击,切削过程容易产生振动,因而限制了工件的表面质量,这种冲击,也加剧了刀具的磨损和破损。铣削的加工精度一般可达IT8—IT7,表面粗糙度为6.3—1.6μm。 普通铣削一般只能加工平面,用成形铣刀也可以加工出固定的曲面。数控铣床可以用软件通过数控系统控制几个轴按一定关系联动,铣出复杂曲面来,这时一般采用球头铣刀。数控铣床对加工叶轮机械的叶片、模具的模芯和型腔等形状复杂的工件,具有特别重要的意义。在切离工件的一般时间内,可以得到一定冷却,因此散热条件较好。按照铣削时主运动速度方向与工件进给方向的相同或相反,又分为顺铣和逆铣。
 
(1)顺铣
 
铣削力的水平分力与工件的进给方向相同,工件台进给丝杠与固定螺母之间一般有间隙存在,因此切削力容易引起工件和工作台一起向前窜动,使进给量突然增大,引起打刀。在铣削铸件或锻件等表面有硬度的工件时,顺铣刀齿首先接触工件硬皮,加剧了铣刀的磨损。 
 
(2)逆铣
 
可以避免顺铣时发生的窜动现象。逆铣时,切削厚度从零开始逐渐增大,因而刀刃开始经历了一段在切削硬化的已加工表面上挤压滑行的阶段,加速了刀具的磨损。同时,逆铣时,铣削力将工件上抬,易引起振动,这是逆铣的不利之处。 
 
适用范围:铣平面、铣台阶、铣沟槽、铣成形面、铣螺旋槽、铣齿轮、切断
 
三、刨削加工
 
刨削加工一般指在刨床上利用刨刀相对于工件做往复直线运动,切除多余材料的加工方法。刨削加工时,刀具的往复直线运动为切削主运动。因此,刨削加工速度慢,生产率较低。刨削加工比铣削加工平稳,刨削加工属粗加工,个别情况下可达到半精加工程度,其精度低于铣削加工,其加工精度一般可达IT8—IT7,表面粗糙度为Ra6.3—1.6μm,精刨平面度可达0.02/1000,表面粗糙度为0.8—0.4μm。 但对于大型铸件的加工具有优越性。
 
适用范围:刨平面、刨垂直面、刨台阶面、刨直角沟槽、刨斜面、刨燕尾槽、刨丁型槽、刨V型槽、刨曲面、刨孔内键槽、刨齿条、刨复合表面
 
四、磨削加工 
 
磨削加工是利用高硬度的人造磨轮(砂轮)作为刀具,在磨床上对工件表面进行切削加工的方法,其主运动是砂轮的旋转。砂轮的磨削过程实际上是磨粒对工件表面的切削、刻削和滑擦三种作用的综合效应。磨削中,磨粒本身也由尖锐逐渐磨钝,使切削作用变差,切削力变大。当切削力超过粘合剂强度时,圆钝的磨粒脱落,露出一层新的磨粒,形成砂轮的“自锐性”。但切屑和碎磨粒仍会将砂轮阻塞。因而,磨削加工一定时间后,需用金刚石车刀等对砂轮进行修整。磨削加工时,由于刀刃很多,所以其切削速度高、加工精度高。磨床是精加工机床,磨削加工精度可达IT6—IT4,表面粗糙度Ra可达1.25—0.01μm,甚至可达0.1—0.008μm。磨削加工的另一特点是可以对淬硬的金属材料进行加工,属于精加工范围,因此往往作为最终加工工序。磨削时,产生热量大,需有充分的切削液进行冷却。按功能不同,磨削还可分为外园磨、内孔磨、平磨等。
 
适用范围:幻外圆磨削、内圆磨削、平面磨削、成形磨削、镙纹磨削、齿轮磨削
 
五、钻削加工
 
在钻床上加工各种内孔的工艺称为钻削加工,是孔加工的最常用方法。钻削加工的精度较低,一般为IT12~IT11,表面粗糙度一般为为Ra5.0~6.3um,在钻削加工后常常采用扩孔和铰孔来进行半精加工和精加工。扩孔采用扩孔钻,铰孔采用铰刀进行加工。铰削加工精度一般为IT9—IT6,表面粗糙度为Ra1.6—0.4μm。扩孔、铰孔时,钻头、铰刀一般顺着原底孔的轴线,无法提高孔的位置精度。
 
适用范围:钻孔、扩孔、铰孔、攻螺纹、锶孔、刮平面
 
六、镗削加工
 
镗削加工利用镗床对已有孔进行扩大孔径并提高质量的加工方法,镗削加工是以镗刀的旋转运动为主。镗销加工可以较正孔的位置。镗削加工精度较高一般为IT9—IT7,表面粗糙度为Ra6.3—0.8mm,但是镗销加工的生产效率低。
 
适用范围:加工高精度孔、多个孔精加工
 
七、齿面加工
 
齿轮齿面加工方法可分为两大类:成形法和展成法。成形法加工齿面所使用的机床一般为普通铣床,刀具为成形铣刀,需要刀具的旋转运动和直线移动这两个简单的成形运动。展成法加工齿面的常用机床为滚齿机、插齿机等。
 
适用范围:齿轮等
 
八、复杂曲面加工
 
三维曲面的切削加工,主要采用仿形铣和数控铣的方法或特种加工方法。仿形铣必须有原型作为靠模。加工中球头仿形头,一直以一定压力接触原型曲面。仿形头的运动变换为电感量,加工放大控制铣床三个轴的运动,形成刀头沿曲面运动的轨迹。铣刀多采用与仿形头等半径的球头铣刀。数控技术的出现为曲面加工提供了更有效的方法。在数控铣床或加工中心上加工时,是通过球头铣刀逐点按坐标值加工而成。采用加工中心加工复杂曲面的优点是:加工中心上有刀库,配备几十把刀具。曲面的粗、精加工,可用不同刀具对凹曲面的不同曲率半径,也可选用适当的刀具。同时,可在一次安装中加工各种辅助表面,如孔、螺纹、槽等。这样充分保证了各表面的相对位置精度。 
 
适用范围:复杂曲面的零部件
 
九、电火花加工
 
电火花加工是利用工具电极和工件电极间瞬时火花放电所产生的高温熔蚀工件表面材料来实现加工的。电火花加工机床一般由脉冲电源、自动进给机构、机床本体及工作液循环过滤系统等部分组成。工件固定在机床工作台上。脉冲电源提供加工所需的能量,其两极分别接在工具电极与工件上。当工具电极与工件在进给机构的驱动下在工作液中相互靠近时,极间电压击穿间隙而产生火花放电,释放大量的热。工件表层吸收热量后达到很高的温度(10000℃以上),其局部材料因熔化甚至气化而被蚀除下来,形成一个微小的凹坑。工作液循环过滤系统强迫清洁的工作液以一定的压力通过工具电极与工件之间的间隙,及时排除电蚀产物,并将电蚀产物从工作液中过滤出去。多次放电的结果,工件表面产生大量凹坑。工具电极在进给机构的驱动下不断下降,其轮廓形状便被“复印”到工件上(工具电极材料尽管也会被蚀除
 
适用范围
 
①加工硬、脆、韧、软和高熔点的导电材料;
 
②加工半导体材料及非导电材料;
 
③加工各种型孔、曲线孔和微小孔;
 
④加工各种立体曲面型腔,如锻模、压铸模、塑料模的模膛;
 
⑤用来进行切断、切割以及进行表面强化、刻写、打印铭牌和标记等。  
 
十、电解加工
 
电解加工是利用金属在电解液中产生阳极溶解的电化学原理对工件进行成形加工的一种方法。工件接直流电源正极,工具接负极,两极之间保持狭小间隙(0.1mm~0.8mm)。具有一定压力(0.5MPa~2.5MPa)的电解液从两极间的间隙中高速15m/s~60m/s)流过。当工具阴极向工件不断进给时,在面对阴极的工件表面上,金属材料按阴极型面的形状不断溶解,电解产物被高速电解液带走,于是工具型面的形状就相应地“复印”在工件上。  
 
适用范围:加工型孔、型腔、复杂型面、小直径深孔、膛线以及进行去毛刺、刻印等。
 
十一、激光加工
 
对工件的激光加工由激光加工机完成。激光加工机通常由激光器、电源、光学系统和机械系统等组成。激光器(常用的有固体激光器和气体激光器)把电能转变为光能,产生所需的激光束,经光学系统聚焦后,照射在工件上进行加工。工件固定在三坐标精密工作台上,由数控系统控制和驱动,完成加工所需的进给运动。 
 
适用范围:金刚石拉丝模、钟表宝石轴承、发散式气冷冲片的多孔蒙皮、发动机喷油咀、航空发动机叶片等的小孔加工以及多种金属材料和非金属材料的切割加工。
 
十二、超声波加工
 
超声波加工是利用超声频(16KHz~25KHz)振动的工具端面冲击工作液中的悬浮磨料,由磨粒对工件表面撞击抛磨来实现对工件加工的一种方法。超声发生器将工频交流电能转变为有一定功率输出的超声频电振荡,通过换能器将此超声频电振荡转变为超声机械振动,借助于振幅扩大棒把振动的位移幅值由0.005mm~0.01mm放大到0.01~0.15mm,驱动工具振动。工具端面在振动中冲击工作液中的悬浮磨粒,使其以很大的速度,不断地撞击、抛磨被加工表面,把加工区域的材料粉碎成很细的微粒后打击下来。虽然每次打击下来的材料很少,但由于打击的频率高,仍有一定的加工速度。由于工作液的循环流动,被打击下来的材料微粒被及时带走。随着工具的逐渐伸入,其形状便“复印”在工件上。 
 
适用范围:难切削材料
 
随着科技的发展,机械加工方法也在逐渐增加,选择机械加工方法的时候一定会进行多方面考虑,包括加工工件表面形状、尺寸精度、位置精度、表面粗糙度等,选择合适的机械加工方法,才能在最小投入下保证工件的质量及加工效率,才能让产生的利益最大化。
In mechanical processing, according to the material and requirements of mechanical processing workpiece can choose different processing methods, understand the common types of mechanical processing and mechanical processing knowledge, can let us choose a more appropriate mechanical processing methods and applicable scope, so how to choose the mechanical processing methods and applicable scope?
 
 
 
 
 
One, turning processing
 
 
 
The method of using lathe to process parts is called turning. In turning, the workpiece rotates to form the main cutting movement. When the cutter moves along the axis of parallel rotation, it forms an inner and outer cylinder. A cone is formed when a tool moves along an oblique line that intersects the axis. On a copying lathe or numerical control lathe, the cutting tool is fed along a curve to form a specific surface of rotation. Using a molding tool, transverse feed, can also be processed out of the rotating surface. Turning can also be processed thread surface, end plane and eccentric shaft. Turning accuracy is generally IT11 - IT6, surface roughness is 12.5-0.8 m. Finishing, up to IT6 - IT5, roughness up to 0.4-0.1 muon. The turning processing productivity is higher, the cutting process is more stable, the cutting tool is simpler.
 
 
 
Scope of application: drilling center hole, drilling hole, reaming hole, tapping thread, turning round, boring hole, turning end face, turning groove, turning surface, turning cone, knurling, turning thread
 
 
 
Second, milling processing
 
 
 
Milling is a method of machining the workpiece with a rotating multi-edge cutter (milling cutter) on the milling machine. The main cutting movement is the rotation of the cutter. In horizontal milling, the formation of a plane is formed by the edges on the outer surface of the milling cutter. In end milling, the plane is formed by the end face edge of the milling cutter. Higher cutting speed can be obtained by increasing the speed of milling cutter. But because the cutter teeth cut into, cut out, the formation of impact, the cutting process is easy to produce vibration, thus limiting the workpiece surface quality, this impact, also intensified the wear and damage of the tool. The milling accuracy is generally up to IT8 -- IT7, and the surface roughness is 6.3 -- 1.6 microns. General milling can only be processed plane, with the form milling cutter can also be processed a fixed surface. Numerical control milling machine can be controlled by software through the numerical control system several axis according to a certain relationship linkage, milling out a complex surface, then generally use ball head milling cutter. Nc milling machine is of great importance for machining the complicated workpiece such as the vane of turbomachinery, the mould core and the cavity. In the general time of cutting off the workpiece, a certain amount of cooling can be obtained, so the heat dissipation conditions are better. According to the direction of the main movement speed when milling and workpiece feed direction of the same or opposite, and is divided into shun milling and inverse milling.
 
 
 
(1) downmilling
 
 
 
The horizontal component of the milling force and the workpiece feed direction is the same, the workpiece table feed screw and the fixed nut between the clearance generally exists, so the cutting force is easy to cause the workpiece and the table to move forward together, make the feed suddenly increased, resulting in a knife. When milling parts with hard surface such as castings or forgings, the teeth of the milling cutter first contact the hard surface of the workpiece, which aggravates the wear of the milling cutter.  
 
 
 
(2) inverse milling
 
 
 
It can avoid the phenomenon of channeling when milling. In reverse milling, the cutting thickness increases gradually from zero, thus the blade begins to experience a period of compression sliding on the machined surface hardened by cutting, accelerating the wear of the tool. At the same time, the inverse milling, milling force will be lifted, easy to cause vibration, this is the disadvantage of the inverse milling.  
 
 
 
Scope of application: milling plane, milling step, milling groove, milling forming surface, milling spiral groove, milling gear, cutting
 
 
 
Three, planing processing
 
 
 
Planing generally refers to the use of planer on the planer relative to the workpiece to do reciprocating linear motion, cutting excess material processing method. When planing, the reciprocating linear motion of the cutter is the main motion of cutting. Therefore, planing processing speed is slow, low productivity. Planing processing is more stable than milling processing, planing processing belongs to rough processing, some cases can reach the degree of semi-finishing, its accuracy is lower than milling processing, the processing accuracy is generally up to IT8 -- IT7, the surface roughness of ra6.3-1.6 microns, planing planeness up to 0.02/1000, the surface roughness of 0.8 -- 0.4 microns. However, it has advantages for processing large castings.
 
 
 
Scope of application: planer plane, planer vertical plane, planer step plane, planer right Angle groove, planer inclined plane, planer doffing groove, planer v-groove, planer curved surface, planer keyway, planer rack, planer compound surface
 
 
 
Four, grinding processing
 
 
 
Grinding is a method of cutting workpiece surface by using high hardness artificial grinding wheel (grinding wheel) as cutter. Its main movement is the rotation of grinding wheel. The grinding process of grinding wheel is actually the comprehensive effect of three effects of abrasive particles on workpiece surface: cutting, cutting and sliding. In grinding, grinding grain itself also gradually blunt by sharp, so that the cutting effect become poor, cutting force. When the cutting force exceeds the strength of the adhesive, the round blunt abrasive grains fall off, exposing a new layer of abrasive grains, forming the "self-sharpness" of the grinding wheel. However, chips and abrasive particles will still block the grinding wheel. Therefore, after grinding for a certain period of time, diamond turning tools are needed to repair the grinding wheel. When grinding, because the blade is many, so its cutting speed is high, machining accuracy is high. Grinding machine is a finishing machine, grinding accuracy up to IT6 - IT4, surface roughness Ra up to 1.25-0.01 muon, even up to 0.1-0.008 muon. Another characteristic of grinding is that it can be used to process hardened metal materials, which belongs to the scope of finishing, so it is often used as the final processing procedure. During grinding, heat is generated and sufficient cutting fluid is needed for cooling. According to different functions, grinding can be divided into outer circular grinding, inner hole grinding, flat grinding and so on.
 
 
 
Scope of application: external grinding, internal grinding, surface grinding, forming grinding, screw grinding, gear grinding
 
 
 
Drilling processing
 
 
 
The process of machining various inner holes on the drilling machine is called drilling processing, which is the most commonly used method of hole processing. The precision of drilling is relatively low, generally ranging from IT12 to IT11, and the surface roughness is generally Ra5.0 to 6.3um. After drilling, reaming and reaming are often used for semi-finishing and finishing. The reaming hole is processed with reamer. The machining accuracy is generally IT9 -- IT6, and the surface roughness is Ra1.6 -- 0.4 microns. When reaming and reaming holes, the drill bit and reamer are generally along the axis of the original bottom hole, which cannot improve the position accuracy of the hole.
 
 
 
Application: drilling, reaming, tapping, strontium hole, scraping plane
 
 
 
Six, boring processing
 
 
 
Boring machining USES boring machine to enlarge aperture and improve quality of existing holes. Boring machining is based on rotary movement of boring tool. Boring pin processing can be compared to the position of the hole. The boring machining precision is generally IT9 -- IT7, the surface roughness is Ra6.3 -- 0.8mm, but the boring pin machining production efficiency is low.
 
 
 
Scope of application: machining high-precision hole, multiple hole finishing
 
 
 
Seven, tooth surface processing
 
 
 
The processing method of gear tooth surface can be divided into two categories: forming method and developing method. The machine tool used to process tooth surface by forming method is general milling machine, and the cutter is forming milling cutter. Shaping process tooth surface commonly used machine tools for gear hobbing machine, gear shaping machine, and so on.
 
 
 
Scope of application: gear, etc
 
 
 
Eight, complex surface processing
 
 
 
Three - dimensional surface machining, the main use of copying milling and CNC milling methods or special processing methods. Copy milling must have a prototype as a copy. In machining, the ball head contour head always contacts the prototype surface with a certain pressure. The motion of the copying head is transformed into the inductance, and the machining magnification controls the movement of the three axes of the milling machine to form the trajectory of the cutter head moving along the surface. Milling cutter and copy head radius of the ball head milling cutter. The appearance of numerical control technology provides a more effective method for surface machining. CNC milling machine or machining center processing, is through the ball head milling cutter point by point according to the coordinate value of processing. The advantage of machining complex surface with machining center is that there is a knife library on the machining center, equipped with dozens of knives. For rough and fine machining of surface, different tools can be used for different curvature radius of concave surface, and appropriate tools can be selected. At the same time, various auxiliary surfaces, such as holes, threads, grooves, etc. can be processed in one installation. In this way, the relative position accuracy of each surface is fully guaranteed.  
 
 
 
Scope of application: parts with complex curved surface
 
 
 
edm
 
 
 
Edm is realized by using high temperature corrosion of workpiece surface materials generated by instantaneous spark discharge between tool electrode and workpiece electrode. Edm machine tools are generally composed of pulse power supply, automatic feeding mechanism, machine body and working fluid circulation filtration system. The workpiece is fixed on the working platform of the machine tool. The pulse power supply provides the energy required for processing, and the two poles are connected to the tool electrode and the workpiece respectively. When the tool electrode and the workpiece are close to each other in the working fluid under the driving of the feeding mechanism, the voltage between the poles breaks down the gap and generates spark discharge, releasing a large amount of heat. The surface layer of the workpiece absorbs heat and reaches a very high temperature (above 10000℃), and its partial materials are eroded down due to melting or even gasification, forming a tiny pit. The working fluid circulation filtration system forces the clean working fluid to pass through the gap between the tool electrode and the workpiece at a certain pressure to timely eliminate the electrical corrosion products and filter them out of the working fluid. As a result of multiple discharges, a large number of pits are generated on the surface of the workpiece. As the tool electrode is driven down by the feed mechanism, its contour shape is "copied" to the workpiece (although the tool electrode material is also eroded)
 
 
 
Scope of application
 
 
 
(1) processing of hard, brittle, tough, soft and high melting point conductive materials;
 
 
 
(2) processing semiconductor materials and non-conductive materials;
 
 
 
(3) processing of various types of holes, curve holes and tiny holes;
 
 
 
(4) processing a variety of three-dimensional surface cavity, such as forging die, die casting die, plastic die chamber;
 
 
 
5 used for cutting, cutting and surface enhancement, engraving, printing nameplate and marking.  
 
 
 
Ten, electrochemical machining
 
 
 
Electrochemical machining (ecm) is a method of forming workpiece by utilizing the electrochemical principle of anodic dissolution of metal in electrolyte. The workpiece is connected to the positive pole of the dc power supply, and the tool is connected to the negative pole, with a narrow gap (0.1mm ~ 0.8mm) between the two poles. The electrolyte with a certain pressure (0.5mpa ~ 2.5mpa) flows through the gap between the poles at a medium speed of 15m/s ~ 60m/s. When the tool cathode is continuously fed into the workpiece, on the workpiece surface facing the cathode, the metal material dissolves continuously according to the shape of the cathode surface, and the electrolytic products are taken away by the high-speed electrolyte, so the shape of the tool surface is "copied" on the workpiece accordingly.  
 
 
 
Application: machining hole, cavity, complex surface, small diameter deep hole, riving, deburring, imprinting, etc.
 
 
 
Eleven, laser processing
 
 
 
The laser processing of workpiece is completed by the laser processing machine. Laser processing machine usually consists of laser, power supply, optical system and mechanical system. Lasers (solid and gas lasers are commonly used) convert electrical energy into light energy, producing the required laser beam, which is focused by the optical system and then shone on the workpiece for processing. The workpiece is fixed on the three-coordinate precision work table and controlled and driven by the numerical control system to complete the feed movement required for machining.  
 
 
 
Scope of application: diamond wire drawing die, precious stone bearing for watch, porous skin for diffused air-cooled punching piece, small hole processing for engine nozzle, aero-engine blade, and cutting processing for various metal and non-metal materials.
 
 
 
Ultrasonic processing
 
 
 
Ultrasonic machining is a method to realize workpiece processing by using suspended abrasive in the working fluid of tool end face impact by ultrasonic frequency (16KHz ~ 25KHz) vibration. The ultrasonic generator converts the ac electric energy of power frequency into ultrasonic electrical oscillation with a certain power output, converts the ultrasonic electrical oscillation into ultrasonic mechanical vibration through the transducer, and amplifies the displacement amplitude of vibration from 0.005mm ~ 0.01mm to 0.01mm ~ 0.15mm with the help of amplitude expansion rod, driving the tool vibration. The end face of the tool strikes the suspended abrasive particles in the working fluid in vibration, making it constantly hit and polished the processed surface with a great speed, smashing the materials in the processing area into very fine particles and striking down. Although the material down each time is very small, but because of the high frequency of the strike, there is still a certain processing speed. Due to the circulating flow of the working fluid, the beaten material particles are carried away in time. As the tool moved in, its shape was copied onto the workpiece.  
 
 
 
Application: hard cutting materials
 
 
 
With the development of science and technology, mechanical processing method are also gradually increase, when choosing machining methods will be in many respects, including machining surface shape, dimensional accuracy, position accuracy, surface roughness, etc., choose the appropriate machining method, can guarantee the quality of the workpiece under the minimum investment and the processing efficiency, can produce benefit maximization.