外文翻译--基本的螺旋锥齿轮【中英文文献译文】
外文翻译-基本的螺旋锥齿轮【中英文文献译文】,中英文文献译文,外文,翻译,基本,螺旋,齿轮,中英文,文献,译文
The Basics of Spiral Bevel Gears1 Gearing Principles Cylindrical and Straight Bevel GearsThe purpose of gears is to transmit motion and torque from one shaft to another, That transmission normally has to occur with a constant ratio, the lowest possible disturbances derived from a straight rack with straight tooth profile. A particular gear, rolling in the rack with constant center distance to the rack, requires involute flank surfaces. A shaping tool with the shape of rack can machine a gear with a perfect involute flank form. Figure 1 shows a cylindrical gear rolling in a rack. In the case of a single index face milling method, the tooth lead function is circular, as the blade in the cutter performs a circular motion, while the generating gear rests in a fixed angular position.The tooth profiling between the cutter and the generating gear does not require any rotation of the generating gear. The virtual generating gear is formed by the cutter head in a non-generating process. In Figure 3, the rotating blades in the cutter head can be understood to represent one tooth of the generating gear.As explained earlier, the generating gear is the bevel gear equivalent of the straight rack for generating a cylindrical gear tooth. The pinion slot produced in that way has two defects. First, the profile will not allow rolling between pinion and generating gear (compare to the rack and cylindrical gear tooth in Figure 1). Second, the pinion slot does not have the proper depth along the face width. As soon as the teeth have a spiral angle and the slot inclines to an angle on an axial plane, the teeth wind around the work gear body. In a fixed angular position, just the heel section, for example, is cut to the proper depth.The roll motion rotates the virtual generating gear and the work gear with the proper ratio while they are engaged (similar to the linear motion of the rack, Figure 1, in conjunction with the gear rotation).That procedure was for machining one slot. To machine the next slot, the cutter withdraws, and the work indexes one pitch. The spiral angle is the inclination angle of the curved tooth tangent to the radius vector from the intersection point of pinion and gear axis (see Figure 4). Because of the curved shape of the tooth length, different points along the lace width have different spiral angles. The nominal spiral angle of the spiral bevel gear or pinion is the angle measured from the center of the tooth.It is possible to use a bevel generating gear that is identical to tile ring gear. File pinion is in that case generated by rolling with the bevel generating gear, and the gear is manufactured simply by plunging the cutter to full depth without rolling (non-generated form cutting).A straight tooth bevel gear set has contact lines that are parallel to the pitch line(Figure 5, top). The first contact between a generating gear tooth and a pinion tooth starts, for example, in the root and moves during the rotation of the two mating members along the path of contact straight up to the top. The contact lines represent the momentary contact between the two flanks in mesh.With a spiral bevel gear set the contact lines are inclined relative to the pitch line orientation. Unlike the contact lines of the straight bevel gear set, the contact lines of the spiral bevel gear set have different lengths. The bottom of figure 5 shows the movement of the contact from heel top to toe root. The very short contact length increases from the beginning of the roll towards the center of the face width and reduces as the roll approaches the exit at the toe end.The contact lines between pinion and generating gear are identical to the contact lines between cutter blades and pinion flanks.2 Single Index Process- Face MillingIn a single index process, just one slot is cut at a time. For the non-generated member only, the cutter rotates and is fed into the work gear to the full depth. After reaching the full depth, the cutter withdraws and the work indexes one pitch to the next desired slot position (Figure 6, right side). The process repeats until all slots have been machined. The resulting flank lead function is a circular arc.Machining a generated member is done by plunging at the heel roll position first. After plunging, the roll motion begins, and generating of the flanks from heel to toe occurs. The flank lead function for a face milled, generated gear is a circular arc that is wound around a conical surface.The manufacturing .of a face milled bevel gear pair is possible in a five-cut process or in a completing process. The five-cut process consists of the following five independent operations: 1. Gear roughing (alternate roughing blades), 2. Gear finishing (alternate finishing blades), 3. Pinion roughing (alternate roughing blades), 4. Pinion finishing convex (inner blades only), and 5. Pinion finishing concave (outer blades only).A completing process uses two combined operations: 1. Gear roughing and finishing (alternate roughing finishing blades) and 2. Pinion roughing and finishing (alternate roughing finishing blades).3 Continuous Indexing Process-Face HobbingA continuous cutting process consists of continuous rotations and a feed motion only. While an outer and an inner blade move through a slot of the work gear, the work gear is rotating in the opposite direction, The relation of the cutter rpm and the work rotation is equivalent to the ratio between the number of work gear teeth and the number cutter head blade groups (starts). The resulting flank lead function is an epicycloid. The effective cutting direction of the blades in the cutter head is not perpendicular to the cutter radius vector (like in the single indexing process). The blades are moved in the cutter head tangentially to an offset position to accommodate the correct orientation with respect to the cutting motion vector. The pitch points on the cutting edge of inner and outer blade have an identical radius. The right slot width is achieved with the angular distance between the outer blade (first) and the following inner blade. The left portion of Figure 6 shows the kinematic relationship and the orientation of the blades relative to cutter and cutting motion.Balancing of the tooth thicknesses between pinion and gear can only be realized by different radii of inner and outer blade pitch points, since the spacing between the blades is given by the cutter head design and therefore remains constant.While one blade group (like shown in Figure 6) is moving through one slot, the work rotates in the opposite direction, such that the next blade group enters the next slot. That way, all the slots around the work gear are cut at about the same time. The feed motion to feed the critter to the full depth position is therefore slower than in the single index process.A non-generated work gear is finished when the full depth position is reached. To get the highest possible spacing accuracy, a dwell time is applied to the non-generated member. The aim of the dwell motion is to allow each blade to move once more to each slot, which takes N slots to pass by, where N is the number of cutter starts times the number of .gear teeth. N is equivalent to as many ring gear revolutions as the cutter has starts.For a generated pinion, a roll motion follows the plunging cycle in the center, roll position (the cutter does not cut the full depth yet). The roll motion after plunging moves the cutting action to the heel; both plunging and rolling to heel is part of the roughing cycle. At the heel roll position, the cutter advances to the full depth position, the cutter rpm increases to a finishing surface speed, and a slow roll motion from heel to toe follows. When arriving at the toe (end roll position), all teeth of the generated work gear or pinion are finished (see Figure 7).4 Heat Treatment of Bevel GearsHeat treatment follows the soft cutting operation. The generally used low carbon steel has to be carburized on the surface, by case hardening for example. The heat treatment is finished with the quenching operation that provides a surface hardness in the range of 60 to 63 Rc (Rockwell C)The pinion may be 3 Rc harder than the ring gear to equalize the wear and reduce the risk of scoringThe core material stays softer and more ductile,with a hardness in the range of 30 to 40 Rc.The distortions from heat treatment are critical to the final hard finishing operationThe kind of heat treatment facility(salt bath,furnace or continuous furnace),as well as the differences between the charges of blank material,has a significant influence On the gear distortionThe gear, which is mostly shaped like a ring,loses its flatness(it gets a face run-out)via the hardening procedureThe pinion,in most cases,is shaped like a long shaft that loses its straightness(radial runout)In addition to the blank body distortions,heat treating causes a distortion of the individual teethThe spiral angle changes,the flank length curvature is reduced and the pressure angle changesTo achieve the best results,attention has to be paid to processing and handling of the parts through the furnace 5 Hard Finishing of Bevel GearsThe final machining operation after heat treatment should provide a good surface finish and remove flank distortions. The most common process used is lapping. Pinion and gear are brought into mesh and rolled under light torque. To provide an abrasive action, a mixture of oil and silicon carbide is poured between the teeth (Figure 8). A relative movement of pinion and gear along their axes and a movement in offset direction is created, such that the contact area moves from toe to heel and back numerous times.The lapping process improves the surface finish,leaves a desirable micro-structure on the flank surfaces and removes heat treat distortions to some extent. The metal removal is not uniform in the different flank sections and varies from set to set, since the pinion and gear are used as tools to hard finish each other. This is the reason why lapped sets have to be built as a pair; lapped pinions and gears are not interchangeable.The lapping surface structure is not oriented in the direction of the contact lines, thus providing a good hydrodynamic oil film between the contact areas. The lapping structure also tends to deliver side bands in a noise frequency analysis, which makes the gear set appear to roll more quietly.During the lapping process, a pinion and a gear are always machined and finished at the same time. The time to lap a pair is equal to or shorter than the time to machine one member using another finishing method. Therefore, lapping is often called the most economical bevel gear finishing process.Another finishing option is grinding of bevel gears, which is limited to face milled (single index) bevel gears. The grinding wheel envelops a single side or an alternate completing cutter (Figure 9).Todays technology does not allow the use of a grinding tool in a continuous indexing process. The advantage of grinding is the manufacturing of an accurate flank surface with a predetermined topography. The process allows the constantly repeated production of equal pans. Building in pairs is not necessary.Lapped pairs used in vehicles require an oil change after the first 1,000 miles because of abrasive particles introduced to the tooth surfaces during lapping. A further advantage of grinding over lapping is that such an oil change is unnecessary with ground spiral bevel gears.A process between lapping and grinding with respect to surface speed and relative motion is honing. Honing trials on bevel gears have been done, but they havent been proven successful.Skiving is a hard cutting process. A tool material such as carbide or boron carbonitride is used on tile cutting edge. The cutting machine setup is identical to that for soft machining. The blade point dimension is wider than the one for soft cutting, such that a 0.005-inch uniform stock removal per flank takes place. Skiving delivers a high quality part accuracy and a fine surface finish. Skiving is applied to small batches of mostly larger gear sets, The advantage of skiving is the use of the same cutter head (only with different blades) and the possible use of the same cutting machine. That makes the investment in machines and tools a minimum.6 Some Bevel Gear ConventionsThe expression bevel gears is used as a general description for straight and spiral bevel gears as well as hypoid gear sets. If the axes of the pinion and gear do not intersect but have a distance in space, the gear set is called a hypoid gear set. The name is derived from the hyperbolic shape of the pitch cones. For simplification, the blanks are still manufactured with a conical shape.The convex gear flank rolls with the concave pinion flank. This pair of flanks is called the drive side. The direction of rotation where those flanks contact the pinion drives is called the drive direction. The drive side direction is always used in vehicles to drive the vehicle forward. The reverse direction is subsequently called the coast side (vehicle rolls downhill, foot is off the gas pedal, wheels drive the engine). In some cases, the coast side is used to drive the vehicle, but it is still called the coast side.Ease-off is the presentation of flank form corrections applied to pinion and/or gear. The ease-off topography in defined in the ring gear coordinate system, regardless of where the corrections were done (pinion, gear or both).Protuberance is a profile relief in the root area of the flank, which prevents flank damage resulting from digging in of the mating tooths top edge. Protuberance is realized with a cutting blade modification.7 Localized Tooth ContactWhen bevel gear sets are cut according to the crown gear or generating gear principle, the result is a conjugate pair of gears. Conjugate means pinion and gear have a line contact in each angular position. While rotating the gear in mesh, the contact line moves from heel top to toe root. The motion transmission happens in each roll position with precisely the same constant ratio. Roll testing is done in specially designed bevel gear test machines. If a marking compound (paint) is brushed onto the flanks of the ring gear member, a roiling in mesh under light torque makes the contact area visible. In the case of a conjugate pair, the contact area is spread out over the entire active flank. That is the official definition of the contact area. It is the summation of all contact lines during the complete roll of one pair of teeth.Conjugate bevel gear pairs are not suitable for operation under load and deflections. Misalignment causes a high stress concentration on the tooth edges. To prevent those stress concentrations, a crowning in face width and profile direction is applied to nearly all bevel pinions. The amount of crowning has a relationship to the expected contact stress and deflections.To analyze tooth contact and crowning, computer programs for tooth contact analysis (TCA) were developed. Figure l0 shows the TCA result of a conjugate bevel gear set. The top section of Figure 10 represents a graphic of the ease-off. The ease-off represents the sum of the flank corrections, regardless of whether they were done in the pinion or gear member. The octoidal profile and curved lead function are filtered out. Therefore the ease-off is a flat zero topography for conjugate gears. The tooth contact is shown below the ease-off. Tooth orientation is indicated with heel, toe and root. The coast and drive sides show a full contact, covering the entire active working area of the flanks. The lower diagram in Figure 10 is the transmission error. Conjugate pairs roll kinematically exactly with each other. That roll is reflected by points on graphs that match the abscissas of the diagrams. Each point of those graphs has a zero value (ZG-direction,), so they cannot be distinguished from the base grid. The base grid and graph are identical and drawn on top of each other. That characterizes a conjugate pair of gear flanks. The transmission graph always displays the motion variation of three adjacent pairs of teeth.To achieve a suitable flank contact, todays flank corrections mostly consist of three elements, shown in Figure 11.Profile crowning (Figure 11,left) is the result of a blade profile curvature. Length crowning (Figure 11, center) can be achieved by modification of the cutter radius or by a tilted cutter head in conjunction with blade angle modification. Flank twist (Figure 11,right) is a kinematic effect resulting from a higher order modulation of the roll ratio (modified roll) or cutter head tilt in conjunction with a machine root angle change.The three mentioned flank modifications can be combined, such that the desirable contact length and width, path of contact direction and transmission variation magnitude are realized. The TCA characteristics (contact pattern and transmission variation) are chosen to suit the gear set for the expected amount of contact stress and gear deflections. 基本的螺旋锥齿轮1 圆柱齿轮传动原理与直锥齿轮齿轮的目的是传递运动和扭矩从一个到另一个轴,即传输通常必须不断发生率,尽可能最低的干扰来自直机架直齿廓。一个特别的装置,在机架轧制不断中心距离固定在机架上,要求渐开线侧表面。阿塑造工具形状的机架可以机齿轮与渐开线侧翼一个完美的形式。图1显示了圆柱齿轮滚动在机架上。在一个单一的指数铣方法,牙齿导致职能是圆形的,因为刀片的刀具进行圆周运动,而产生齿轮在于固定角位置。描出在切削刀和引起的齿轮之间的牙不要求引起的齿轮的任何自转。 真正引起的齿轮由刀头在一个非引起的过程中形成。在表3,在刀头的转动的刀片可以被了解代表引起的齿轮的一颗牙。如前所述,引起的齿轮是平直的机架的斜齿轮等值引起的一颗圆柱形齿轮牙。插槽的齿轮生产的这种方式有两个缺陷。首先,外形不会准许滚动在插槽的齿轮生产和引起齿轮(与机架和圆柱形齿轮齿比较在表1)。其次,插槽的齿轮生产没有沿面孔宽度适当的深度。当轮齿有一个螺旋角和插槽倾向于一个角度对轴向平面,轮齿就绕在工作齿轮体附近。例如,在一个固定的角位脚跟部分被削减到适当的深度。滚动转动的虚拟生成齿轮和工作齿轮以适当的比率,当他们允诺时(类似于直线运动的机架上,图1 ,结合齿轮旋转)。这一程序是一个槽的加工。机器下次插槽,刀具撤出,和工作把一调子编入索引。螺旋角度是弯曲的牙正切的倾角对从交点的向径鸟翼末端和齿轮轴(参见图4)。 由于轮齿长度的弯曲的形状,沿鞋带宽度的不同的点有不同的螺旋角度。螺旋斜齿轮或鸟翼末端的有名无实的螺旋角度是从牙的中心计量的角度。使用与瓦片冠状齿轮是相同的一个二面对切的生成齿轮是可能的。文件齿轮是在这种情况下所产生的滚动生成与锥齿轮和齿轮制造仅仅通过使刀具全面深入的不滚动(非生成的形式切割)。直齿锥齿轮设置了接触线,是平行的节线(图5 ,顶端)。第一次接触生成齿轮和小齿轮齿开始,例如,在根和行动期间轮流担任的两个交配成员沿着联系起来顶端。接触线代表两个侧面网格一时之间的联系的。随着螺旋锥齿轮的接触线设置倾向于相对节线的方向。不同的接触线的设置直齿圆锥齿轮,接触线的螺旋锥齿轮设定有不同的长度。底部图5显示接触的运动从脚跟上面到脚趾根。当卷接近出口在脚趾末端,非常短的接触长度增加从最初卷朝面孔宽度的中间并且减少。小齿轮和生成齿轮之间的接触线与在刀片和小齿轮侧面之间的接触线线是相同的。2 单指数过程端铣在一个指数过程中,只有一个插槽被切断的时间。非成员只能生成,刀具旋转,并反馈到工作齿轮的全面深入。经过全面深入的接触,刀具撤回和工作指标之一间距下一期望插槽的位置(图6 ,右侧)。重复这一过程,直到所有插槽已加工。由此产生的侧翼导致功能是一个圆弧。 用机器制造一名引起的成员由首先浸入完成在脚跟卷位置。在浸入以后,滚动开始,并且引起侧面从脚跟到脚趾发生。被碾碎的面孔的侧面主角作用,引起的齿轮是在圆锥形表面附近受损的圆弧。端铣锥齿轮的制造在五次切削过程或在一个完成的过程中是可能的。五次切削过程包括以下五个独立操作:1,齿轮粗磨(供选择粗磨刀片),2,齿轮精整(供选择精整刀片), 3,齿轮粗加工(候补粗加工刀片), 4,齿轮加工的凹面(仅内在刀片)和5,齿轮加工的凹面(仅外面刀片)。一个完成的过程使用二个联合操作:1,齿轮粗加工和精加工(候补粗加工整理刀片)和2,小齿轮齿轮粗加工和精加工(候补粗加工整理刀片)。3 连续的索引编制过程-面孔滚铣一连续切削过程包括连续旋转和进给运动。虽然外部和内部的刀片移动插槽齿轮的工作,工作齿轮旋转方向相反的关系,刀具转速和轮换的工作,就等于将之间的比例,一些工作齿轮和一些刀头刀片组(启动) 。由此产生的侧翼导致功能是一个外摆线。有效切割方向的叶片在刀头不是垂直于刀具半径载体(如在单一索引程序) 。叶片被移到在刀头切一个抵消的立场,以适应的正确方向对切削运动矢量。比赛分上最先进的内部和外部的刀片有一个相同的半径。槽宽度的权利是实现与角之间的距离外刀片(第一)和下面的内层刀片。左边的图6显示了运动学关系和方向的叶片相对刀具和切削运动。平衡齿厚齿轮和齿轮之间才能实现不同的半径内,外叶片间距点,因为刀片之间的间距是由刀头设计,因此保持不变。虽然有一个刀片组(如图6 )正在通过一个插槽,工作旋转方向相反,例如,下叶片组进入下插槽。这样一来,所有的插槽周围的工作齿轮切割大约在同一时间。进给运动深入最大深度位置,因此速度慢于在单一指数进程。非工作齿轮生成完成时,充分深入的位置是到达。要获得尽可能高的间距精确度,停留时间是适用于非生成部件。停留运动的目的是为了让每一个刀片将再次给每个插槽,其中N插槽通过的,其中N是一些刀具开始倍的齿轮。N是相当于许多齿圈变化的刀已经启动。为引起的鸟翼末端,滚动在中心,卷位置跟随浸入的周期(切削刀不切开最大的深度)。 滚动在浸入以后移动切口行动向脚跟; 浸入和滚动停顿是粗磨周期的一部分。 在脚跟卷位置,切削刀推进到最大的深度位置,切削刀rpm增加到精整表面速度,并且缓慢的滚动从脚跟到脚趾跟随。 当到达脚趾(末端卷位置)时,引起的工作的所有牙适应或完成鸟翼末端(参见图7)。 4 锥齿轮的热处理热处理如下软切割作业。一般用于低碳钢,必须渗碳表面上,由表面硬化的例子。热处理后的淬火运作,它提供了表面硬度范围为60至63红细胞(罗克韦尔C )来完成。该齿轮可能更难3红细胞比齿圈有同等的磨损和降低风险的.核心材料保持更加柔和,更有韧性,具有硬度范围为30至40个红细胞。扭曲的热处理是至关重要的最后努力完成手术种热处理设施(盐浴炉或连续炉) ,以及之间的分歧收费空白材料,具有重大影响的齿轮失真。齿轮,其中大部分是像一个环,即失去其平坦度(它得到面临跳动)。通过硬化齿轮,在大多数情况下,是像一个长轴是失去其直线度(径向运行出)。除了空白身体扭曲,热处理造成的单个轮齿变形。螺旋角的变化,侧长度曲率降低和压力角变化,为了取得最佳效果,应当注意向加工和处理对部分通过熔炉。环形齿轮的淬火保证平整度好的热处理环形齿轮,例如。5 锥齿轮坚硬精整最后加工操作热处理后应提供一个良好的表面光洁度和删除侧翼扭曲。最常见的过程中使用的研磨。齿轮和齿轮被带进网推出光扭矩。提供研磨行动,混合石油和碳化硅倒入牙齿之间(图8 )。相对运动的齿轮和齿轮轴和沿其变动方向是建立抵消,这种接触面积从脚趾到脚跟,并回到多次。
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