外文翻譯--基本的螺旋錐齒輪【中英文文獻譯文】,中英文文獻譯文,外文,翻譯,基本,螺旋,齒輪,中英文,文獻,譯文 The Basics of Spiral Bevel Gears 1 Gearing Principles Cylindrical and Straight Bevel Gears The 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 Milling In 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 Hobbing A 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 Gears Heat 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 scoring．The 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 operation．The 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 distortion．The gear, which is mostly shaped like a ring，loses its flatness(it gets a face run-out)．via the hardening procedure．The pinion，in most cases，is shaped like a long shaft that loses its straightness(radial run—out)． In addition to the blank body distortions，heat treating causes a distortion of the individual teeth．The spiral angle changes，the flank length curvature is reduced and the pressure angle changes．To achieve the best results，attention has to be paid to processing and handling of the parts through the furnace． 5 Hard Finishing of Bevel Gears The 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).Today's 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 haven't 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 Conventions The 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 tooth's top edge. Protuberance is realized with a cutting blade modification. 7 Localized Tooth Contact When 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, today's 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. 基本的螺旋錐齒輪 1 圓柱齒輪傳動原理與直錐齒輪 齒輪的目的是傳遞運動和扭矩從一個到另一個軸，即傳輸通常必須不斷發(fā)生率，盡可能最低的干擾來自直機架直齒廓。一個特別的裝置，在機架軋制不斷中心距離固定在機架上，要求漸開線側(cè)表面。阿塑造工具形狀的機架可以機齒輪與漸開線側(cè)翼一個完美的形式。圖1顯示了圓柱齒輪滾動在機架上。 在一個單一的指數(shù)銑方法，牙齒導致職能是圓形的，因為刀片的刀具進行圓周運動，而產(chǎn)生齒輪在于固定角位置。 描出在切削刀和引起的齒輪之間的牙不要求引起的齒輪的任何自轉(zhuǎn)。 真正引起的齒輪由刀頭在一個非引起的過程中形成。在表3，在刀頭的轉(zhuǎn)動的刀片可以被了解代表引起的齒輪的一顆牙。 如前所述，引起的齒輪是平直的機架的斜齒輪等值引起的一顆圓柱形齒輪牙。插槽的齒輪生產(chǎn)的這種方式有兩個缺陷。首先，外形不會準許滾動在插槽的齒輪生產(chǎn)和引起齒輪(與機架和圓柱形齒輪齒比較在表1)。其次，插槽的齒輪生產(chǎn)沒有沿面孔寬度適當?shù)纳疃?。當輪齒有一個螺旋角和插槽傾向于一個角度對軸向平面，輪齒就繞在工作齒輪體附近。例如，在一個固定的角位腳跟部分被削減到適當?shù)纳疃取? 滾動轉(zhuǎn)動的虛擬生成齒輪和工作齒輪以適當?shù)谋嚷?，當他們允諾時(類似于直線運動的機架上，圖1 ，結合齒輪旋轉(zhuǎn))。 這一程序是一個槽的加工。機器下次插槽，刀具撤出，和工作把一調(diào)子編入索引。螺旋角度是彎曲的牙正切的傾角對從交點的向徑鳥翼末端和齒輪軸(參見圖4)。 由于輪齒長度的彎曲的形狀，沿鞋帶寬度的不同的點有不同的螺旋角度。螺旋斜齒輪或鳥翼末端的有名無實的螺旋角度是從牙的中心計量的角度。 使用與瓦片冠狀齒輪是相同的一個二面對切的生成齒輪是可能的。文件齒輪是在這種情況下所產(chǎn)生的滾動生成與錐齒輪和齒輪制造僅僅通過使刀具全面深入的不滾動（非生成的形式切割）。 直齒錐齒輪設置了接觸線，是平行的節(jié)線（圖5 ，頂端）。第一次接觸生成齒輪和小齒輪齒開始，例如，在根和行動期間輪流擔任的兩個交配成員沿著聯(lián)系起來頂端。接觸線代表兩個側(cè)面網(wǎng)格一時之間的聯(lián)系的。 隨著螺旋錐齒輪的接觸線設置傾向于相對節(jié)線的方向。不同的接觸線的設置直齒圓錐齒輪，接觸線的螺旋錐齒輪設定有不同的長度。底部圖5顯示接觸的運動從腳跟上面到腳趾根。當卷接近出口在腳趾末端，非常短的接觸長度增加從最初卷朝面孔寬度的中間并且減少。 小齒輪和生成齒輪之間的接觸線與在刀片和小齒輪側(cè)面之間的接觸線線是相同的。 2 單指數(shù)過程—端銑 在一個指數(shù)過程中，只有一個插槽被切斷的時間。非成員只能生成，刀具旋轉(zhuǎn)，并反饋到工作齒輪的全面深入。經(jīng)過全面深入的接觸，刀具撤回和工作指標之一間距下一期望插槽的位置（圖6 ，右側(cè)）。重復這一過程，直到所有插槽已加工。由此產(chǎn)生的側(cè)翼導致功能是一個圓弧。 用機器制造一名引起的成員由首先浸入完成在腳跟卷位置。在浸入以后，滾動開始，并且引起側(cè)面從腳跟到腳趾發(fā)生。被碾碎的面孔的側(cè)面主角作用，引起的齒輪是在圓錐形表面附近受損的圓弧。 端銑錐齒輪的制造在五次切削過程或在一個完成的過程中是可能的。五次切削過程包括以下五個獨立操作： 1，齒輪粗磨(供選擇粗磨刀片)， 2，齒輪精整(供選擇精整刀片)， 3，齒輪粗加工（候補粗加工刀片）， 4，齒輪加工的凹面(僅內(nèi)在刀片)和 5，齒輪加工的凹面(僅外面刀片)。 一個完成的過程使用二個聯(lián)合操作： 1，齒輪粗加工和精加工（候補粗加工整理刀片）和 2，小齒輪齒輪粗加工和精加工（候補粗加工整理刀片）。 3 連續(xù)的索引編制過程--面孔滾銑 一連續(xù)切削過程包括連續(xù)旋轉(zhuǎn)和進給運動。雖然外部和內(nèi)部的刀片移動插槽齒輪的工作，工作齒輪旋轉(zhuǎn)方向相反的關系，刀具轉(zhuǎn)速和輪換的工作，就等于將之間的比例，一些工作齒輪和一些刀頭刀片組（啟動） 。由此產(chǎn)生的側(cè)翼導致功能是一個外擺線。有效切割方向的葉片在刀頭不是垂直于刀具半徑載體（如在單一索引程序） 。葉片被移到在刀頭切一個抵消的立場，以適應的正確方向?qū)η邢鬟\動矢量。比賽分上最先進的內(nèi)部和外部的刀片有一個相同的半徑。槽寬度的權利是實現(xiàn)與角之間的距離外刀片（第一）和下面的內(nèi)層刀片。左邊的圖6顯示了運動學關系和方向的葉片相對刀具和切削運動。 平衡齒厚齒輪和齒輪之間才能實現(xiàn)不同的半徑內(nèi)，外葉片間距點，因為刀片之間的間距是由刀頭設計，因此保持不變。 雖然有一個刀片組（如圖6 ）正在通過一個插槽，工作旋轉(zhuǎn)方向相反，例如，下葉片組進入下插槽。這樣一來，所有的插槽周圍的工作齒輪切割大約在同一時間。進給運動深入最大深度位置，因此速度慢于在單一指數(shù)進程。 非工作齒輪生成完成時，充分深入的位置是到達。要獲得盡可能高的間距精確度，停留時間是適用于非生成部件。停留運動的目的是為了讓每一個刀片將再次給每個插槽，其中N插槽通過的，其中N是一些刀具開始倍的齒輪。N是相當于許多齒圈變化的刀已經(jīng)啟動。 為引起的鳥翼末端，滾動在中心，卷位置跟隨浸入的周期(切削刀不切開最大的深度)。 滾動在浸入以后移動切口行動向腳跟; 浸入和滾動停頓是粗磨周期的一部分。 在腳跟卷位置，切削刀推進到最大的深度位置，切削刀rpm增加到精整表面速度，并且緩慢的滾動從腳跟到腳趾跟隨。 當?shù)竭_腳趾(末端卷位置)時，引起的工作的所有牙適應或完成鳥翼末端(參見圖7)。 4 錐齒輪的熱處理 熱處理如下軟切割作業(yè)。一般用于低碳鋼，必須滲碳表面上，由表面硬化的例子。熱處理后的淬火運作，它提供了表面硬度范圍為60至63紅細胞（羅克韋爾C ）來完成。該齒輪可能更難3紅細胞比齒圈有同等的磨損和降低風險的.核心材料保持更加柔和，更有韌性，具有硬度范圍為30至40個紅細胞。 扭曲的熱處理是至關重要的最后努力完成手術種熱處理設施（鹽浴爐或連續(xù)爐） ，以及之間的分歧收費空白材料，具有重大影響的齒輪失真。齒輪，其中大部分是像一個環(huán)，即失去其平坦度（它得到面臨跳動）。通過硬化齒輪，在大多數(shù)情況下，是像一個長軸是失去其直線度（徑向運行出）。 除了空白身體扭曲，熱處理造成的單個輪齒變形。螺旋角的變化，側(cè)長度曲率降低和壓力角變化，為了取得最佳效果，應當注意向加工和處理對部分通過熔爐。環(huán)形齒輪的淬火保證平整度好的熱處理環(huán)形齒輪，例如。 5 錐齒輪堅硬精整 最后加工操作熱處理后應提供一個良好的表面光潔度和刪除側(cè)翼扭曲。最常見的過程中使用的研磨。齒輪和齒輪被帶進網(wǎng)推出光扭矩。提供研磨行動，混合石油和碳化硅倒入牙齒之間（圖8 ）。相對運動的齒輪和齒輪軸和沿其變動方向是建立抵消，這種接觸面積從腳趾到腳跟，并回到多次。