外文翻譯--plc模塊控制回轉工作臺在三軸數控銑床銑削螺旋傘齒輪中的應用

1、<p>　　本科生畢業(yè)設計 (論文)</p><p><b>　　外 文 翻 譯</b></p><p>　　北華航天工業(yè)學院教務處制</p><p>　密 級</p><p>　分類號</p><p>　編 號</p><p>　成 績</p>

2、<p>　　注：1。 指導教師對譯文進行評閱時應注意以下幾個方面：①翻譯的外文文獻與畢業(yè)設計（論文）的主題是否高度相關，并作為外文參考文獻列入畢業(yè)設計（論文）的參考文獻；②翻譯的外文文獻字數是否達到規(guī)定數量（3 000字以上）；③譯文語言是否準確、通順、具有參考價值。</p><p>　　2。 外文原文應以附件的方式置于譯文之后。</p><p><b>　　附件2

3、：外文原文</b></p><p>　　Use of PLC module to control a rotary table to cut spiral bevel gear with three-axis CNC milling</p><p>　　S. Mohsen Safavi & S. Saeed Mirian & Reza Abedinzadeh &

4、amp; Mehdi Karimian</p><p>　　Received: 25 November 2008 / Accepted: 23 November 2009 # Springer-Verlag London Limited 2009</p><p><b>　　Abstract </b></p><p>　　CNC machini

5、ng nowadays makes more use of "Mechatronics" increasingly. Combining numerical control with mechanic, electric, and data processing systems can lead to new methods of production. In recent years, the developmen

6、t of CNC has made it possible to perform nonlinear correction motions for the cutting of spiral bevel gears. In this paper, we attempt to manufacture the spiral bevel gear using a three-axis CNC milling machine interface

7、d with an additional PLC module based on traditional discon</p><p>　　Keywords：Gear manufacturing . Spiral bevel gear .CAD/CAM/CAE . CNC . PLC . AC motor . Inverter .Proximity sensors . Photoelectric sensors

8、. Rotary encoder</p><p>　　1 Introduction</p><p>　　Gears are important and precision mechanisms for industrial machinery as a means for mechanical power or motion transmission between parallel, i

9、ntersecting and nonintersecting cross-axis shafts. Although hidden from sight, gears are one of the most important mechanical elements in our civilization. They operate at almost unlimited speeds under a wide variety of

10、conditions. The machines and processes that have been developed for producing gears are among the most existing ingenious ones. Whether </p><p>　　1. Blanking</p><p>　　2. Gear cutting</p>

11、<p>　　3. Heat treatment</p><p>　　4. Grinding</p><p>　　Depending on their type and application or required strength and resistance, gears are manufactured by casting, extruding, forging, pow

12、der metallurgy, plastic molding, gear rolling, and machining. Among these processes, machining is more frequently used for high-precise gears. Among the various types of gears, the spiral bevel gears (SBG) are the most c

13、omplex type and are used to transmit the rotational motion between angularly crossed shafts.</p><p>　　SBGs have teeth curved longitudinally along the length of the teeth. The main advantage of these gears ov

14、er the straight-toothed varieties lies in the fact that more teeth are in contact at the same time because of the curve-shaped contour of the teeth and so a smoother meshing action between the mating pair is ensured. The

15、 design and manufacturing of spiral bevel gears is still a hot topic of research that is vital for application of such gears in helicopter transmissions, motorcycle gears, red</p><p>　　Previous studies on ge

16、ars have been mainly concerned with the design and analysis of gears. The geometric characteristics and design parameters of gears have been studied. Tsai and Chin presented a mathematical surface model for bevel gears (

17、straight and SBGs) based on basic gearing kinematcis and involute geometry along the tangent planes. Later, this method was compared with another model based on exact spherical involute curves by Al-daccak et al. Shunmug

18、an et al. presented a different model,</p><p>　　For crown gears, a few results are available. Litvin and Kim suggested a generation method for an involute curve from a modified base circle for a spur gear. U

19、meyama designed a standard profile at the pitch circle and a modified profile at the top/bottom face gear with a determination of the modification value for transmission error of helical gear. Tamura et al. studied a poi

20、nt contact model for a bevel gear using a flat surface tooth. These studies are concerned with the generation of the toot</p><p>　　In this paper, we attempt to present a new manufacturing procedure of SBGs b

21、y using a three-axis milling machine interfaced with a PLC module which operates as an indexing table. In terms of production rate, it is obvious that this method will be lower than that of the special machine tool. Othe

22、r than production rate, this method is advantageous in the following respects: (1) the conventional method requires a large investment for obtaining various kinds of special machinery and cutters dedicate</p><

23、p>　　2 Geometric specifications of the spiral bevel gears</p><p>　　Most of the time, the geometric parameters of a gear are provided with an engineering drawing. Some parameters (principal parameters) are

24、required for defining the geometry. To calculate these parameters, we have used “drive component development software” called GearTrax. </p><p>　　The design of spiral bevel gear requires high-accuracy mathem

25、atical calculations, and the generation of such gear drives requires not only high-quality equipment and tools for manufacturing of such gear drives but also the development of the proper machine-tool settings. Such sett

26、ings are not standardized but have to be determined for each case of design (depending on geometric parameters of the gear drive and generating tools) to guarantee the required quality of the gear drives.</p><

27、p>　　3 Manufacturing the SBG</p><p>　　As it was discussed in the introduction, by machining, all types of gears can be made in all sizes, and machining is still unsurpassed for gears having very high accur

28、acy. Form milling is one of the most common machining processes used to manufacture any types of gears. The cutter has the same form as the space between adjacent teeth. Standard cutters usually are employed in form-cutt

29、ing gears. In the USA, these cutters come in eight sizes for each diametral pitch and will cut gears having the n</p><p>　　As it is shown in Eq. 1, velocity ratio of face hobbing process depends on tooth num

30、ber of tool and generating gear: </p><p><b>　?。?）</b></p><p>　　where, wt and wc denote the angular velocities of the tool and generating gear; Nt and Nc denote the number of the blad

31、e groups and the tooth number of the generating gear. </p><p>　　The radii of the rolling circles of the generating gear and the tool are determined by Eqs. 2 and 3:</p><p><b>　?。?）</b&g

32、t;</p><p><b>　?。?）</b></p><p>　　where s is the machine radial setting.</p><p>　　The generating crown gear can be considered as a special case of a bevel gear with 90

33、6; pitch angle. Therefore, a generic term “generating gear” is used. The concept of complementary generating crown gear is considered when the generated mating tooth surfaces of the pinion and the gear are conjugate. In

34、practice, in order to introduce mismatch of the mating tooth surfaces, the generating gears for the pinion and the gear may not be complementarily identical. The rotation of the generating gear is</p><p>　　T

35、o manufacture the SBGs with the three-axis CNC milling machine, we first test the process by developing a CAD/CAM system composed of geometric modeling and graphic simulation modules. The commercial software Solidworks i

36、s used for creating CAD model and MSC. Visual NASTRAN 4D (CAE system of the kinematic analysis of the mechanisms by means of their 3D models) is used for simulating the process of gear manufacturing and its analytical re

37、sults.</p><p>　　As far as machine tool configuration is concerned, it is obvious that a rotational motion of the workpiece is required for NC machining of the SBGs. Based on the machinability analysis, at le

38、ast four-axis controls are required for NC machining of SBGs by one setup. Thus, a rotary table to be interfaced with the three-axis milling machine is required. Form cutting or form milling is used in our tests. The too

39、l is fed radially toward the center of the gear blank to the desired tooth depth, then ac</p><p>　　We used spiral bevel gear created in GearTrax in order to simulate operating sequence and then estimate some

40、 machining parameters such as initial height of end mill, location of proximity sensors, motor torque, motor speed, and rotation frequency. For example, in SolidWorks, distance between end mill and the apex of SBG was 14

41、.7 mm which we used to locate the spindle vertically along the z-axis. </p><p>　　Also, according to the graph report of CAE system which we used, motor angular velocity and motor torque are 1 rpm and 48 Nm,

42、respectively. </p><p>　　Mastercam is a mechanical software that can be used to generate toolpaths for machining. According to whole depth and face width of the gear, a rectangular contour was designed as too

43、lpath in our cutting procedure. </p><p>　　Other machining parameters and tool’s specifications were also submitted to the Tool Path menu of software. In contour window, there are two options which we use:<

44、;/p><p>　　1. Multipasses which enable multiple stepovers of the tool, allowing for greater control of stock removal.</p><p>　　2. Lead in/out which extend or shorten the toolpath before making entry

45、/exit moves without creating additional geometry, which is helpful when working with control compensation and makes it possible to program solid contours in less time.</p><p>　　Although the form cutting of t

46、his kind of gears is currently done on universal milling machine, using an indexing head, the process is slow and requires skilled labor and operator. The cutter is mounted on an arbor, and a dividing head is used to rev

47、olve (required to cut the gear tooth) and index the gear blank. The table is set at an angle equals to the spiral angle (35°), and the dividing head is geared to the longitudinal feed screw of the table so that the

48、gear blank will rotate as it moves </p><p>　　In the presented method, we have used an alternating current (AC) motor interfaced with a worm gearbox. Worm gearbox is used to reduce the output speed of AC moto

49、r and also to set the angle between the tooth trace and the element of the pitch cone, known as spiral angle. </p><p>　　Since synchronization between tool path planning and rotary motion of outward shaft of

50、worm gearbox is required, a mechatronics system to control all the four axes (one-axis motion for the rotary table and three-axis motion for the cutting tool) was used simultaneously.</p><p>　　At the same ti

51、me we used ladder diagram, common program language to operate the PLC in the mechatronics system.</p><p>　　The operation of the PLC based on the ladder diagram is as follows:</p><p>　　Step 1 Rea

52、d the external input signal, such as the status of sensors or rotary encoder.</p><p>　　Step 2 Calculate output signal, according to the value of the input signal in step 1 and send it to AC drive (Inverter)

53、to run the AC motor in forward/reverse direction or turn the motor for a special angle (circular pitch) using a rotary encoder. Having set up the CNC milling machine, the procedure of the whole system is accomplished in

54、five stages:</p><p>　　Stage 1 Form cutter reaches the first proximity sensor. As soon as sensor 1 detects the form cutter, it sends a +5-V signal to the PLC. As it is mentioned before, PLC sends out an outpu

55、t signal to the AC drive to run the motor in forward direction.</p><p>　　Stage 2 Form cutter machines the rotating workpiece with respect to the toolpath has been generated in Mastercam.</p><p>

56、　　Stage 3 Cutting tool reaches the second proximity sensor. Detecting form cutter by sensor 2, it sends the second signal to the PLC and PLC sends a stop command to the inverter.</p><p>　　Stage 4 Milling too

57、l withdraws the stopped workpiece and returns to its first place. Simultaneously, AC drive runs the motor in backward direction until the shaft reaches the first position which the receiver of photoelectric sensor sees t

58、he transmitted radiation passes through the longitudinal crack on the output shaft.</p><p>　　Stage 5 Stages 1 through 4 continue until the first tooth space is cut. PLC counts a number for each of the above

59、four stages until it reaches the predefined number of machining sequences. Then, it sends out a signal to the AC drive to index the gear blank equal to diametral pitch, and all the above stages will be repeated again. Th

60、e diametral pitch is measured by a 1,024-pulse/revolution rotary encoder.</p><p>　　In an advantageous embodiment of the method according to the present invention, machining time is one of the most factors wh

61、ich have been greatly noted. For example, it took only 2 min to cut one tooth space completely. While, in traditional method, it took more than half an hour to cut same tooth space.</p><p>　　In a further adv

62、antageous embodiment of the present invention with respect to manual cutting, the instant for the angular compensation of the cutter head is set shortly before the end of the plunge process.</p><p>　　4 Machi

63、ning strategy</p><p>　　The workpiece is wood, and the blank material is premachined as a conic (face angle of the gear) form by turning operation. Standard cutter No. 5 used in our experiment is mounted on t

64、he machine spindle, and the gear blank is mounted on outward shaft of worm gearbox. The tool is fed subsequently (around 30 machining sequences to prevent spoiling work) toward the center of the gear blank to the desired

65、 tooth depth. When one tooth space has been completed, the tool is withdrawn; the gear blank is </p><p>　　5 Conclusions</p><p>　　In this paper, we attempted to manufacture the spiral bevel gear

66、using a three-axis CNC milling machine based on form milling method. For such a purpose, we investigated a CAD/CAM model of cutting procedure and also tool path computing algorithm. All previous works have been concerned

67、 with the design aspect using complicated mathematical procedure, and experimental manufacturing methods have not been explicitly focused. Basically, form cutting uses a simple and flexible method of machining of ge</

68、p><p>　　method in which dedicated machine tools is required, the presented method can easily be modified to produce any type and size of SBGs or any other types of gears. In comparison to manual cutting machine

69、, it is a complete automatic method in which all machining parameters are derived from the computer model. It is also a multideception system (use of mechatronic and CNC systems) which is a dynamic and constant evolving