齿轮机械机构类中英文翻译@外文翻译@外文文献翻译

外文原文 Gears Gears are vital factors in machinery ,which are uses to transmit power or motion from one shaft to another .They may be used only to transmit motion from one part of a machine to another,or they may be used to change the speed or the torque of one shaft with with relation to another.One of the first mechanism invented using gears wad the clock.In fact,a clock is little more than a train of gears.Considerable study and research have been made on gears in recent years because of their wide use under exacting conditions.They have to transmit heavier loads and run at high speeds than ever before.The engineers and the machinists all consider gearing the prime element in nearly all classes of machinery. Super Gears Spur gears will be considered first for several reasons.In the first place ,they are simplest and the least expensive of gears and they may be used to transmit power between parallel shafts,also,spur gears definitions are usually applicable to other types .It is important go understand the following definitions,since they are important factors in the design of any equipment utilizing gears. Diametric Pitch The number of teeth per inch of pitch cirle diameter .The diameter pitch is usually an integer .A small number for the pitch implies a large tooth size.Meshing spur gears must have the same diameter pitch .The speed ratio is based on the fact that meshing gears may have different-sized pitch circles and hence different number of teeth. Circular Pitch The distance from a point on one tooth to the corresponding point on an adjacent tooth ,measrued along the pitch circle.This is a liner dimension and thus bas liner units. Pitch Circle The circle on which the ratio of the gear set is based,when two gears are meshing ,the two pitch circles must be exactly tangent if the gears are to function properly.The tangency point is known as the pitch point. Pressure Angle The angle between the line of action and a line perpendicular to the centerlines of the two gears in mesing .Pressure Angles for spur gears are usually 14.5 or 20 degrees,although other values can be used.Meshing gears must have the same pressure angles.In the case of a rack,the teeth have the straight sides inclined at an angle corresponding to the pressure angle. Base Circle A circle tangent to the line of action (or pressure line ) .The base circle is the imaginary circle about which an involutes cure is developed .Most spur gears follow an involutes cure from the base circle to the top of the tootch,this cure can be visualized by observing a point on a taut cord an it is unwound from a cylinder .In a gear ,the cylinder is the best circle. Addendum The radial distance form the pitch circle to the top of the tooth . Dedendum The radial distance from file pitch circle to the root of the tooth. Clearance The difference between the addendum and the addendum. Face Width The width of the tooth measured axially. Face The surface between the pitch circle and the top of the tooth. Flank The surface between the pitch circle and the bottom of the tooth. Helical Gears These gears have their tooth element at an angle or helix to the axis of the gear.They are more difficult and expensive to make than spur gears,but are quieter and stronger. They may be used to transmit power between parallel shafts at an angle to each in the same or different planes. Herringbone Gears A herringbone gear is equivalent to a right-hand and a left-hand helical gear placed side by side.Because of the angle of the tooth,helical gears create considerable side thrust on the shaft. A herringbone gear corrects this thrust by neutralizing it ,allowing the use of a small thrust bearing instead of a large one and perhaps eliminating one altogether.Often a central groove is made round the gear for ease in machining. Bevel Gears Bevel gears are used to connect shafts, which are not parallel to each other.Usually the shafts are 90 deg.To each other, but they may be more or less than 90 deg.The two meshing gears may have the same number of teeth for the purpose of changing direction of motion only,or they may have a different number of teeth for the purpose of changing both speed and direction .The faces of the teeth lie on the surface of the frustum of a cone,therefore the teeth elements are not parallel to each other it can be seen that this lack of parallelism creates a machining problem so that two passes with a tool must be made.The tooth elements may be straight or spiral ,so that we have plain anti spiral evel gears. Worm and Worm Gears A worm-and-worm-gear combination is used chiefly where it is desired to obtain a high gear reduction in a limited space,normally the worm drivers the worm gear and is not reversible ,that is to say,the worm gear can not drive the worm.Most worms can be rotated in either direction,clockwise or counterclockwise. Racks A rack is a gear with an infinite radius,or a gear with its perimeter stretched out into a straight line.It is used to change reciprocating motion to rotary motion or vice versa.A lathe rack and pinion is a good example of this mechanism. Various materials are used in manufacturing gears .Usually,the materials selected depends on the method used for making the gear and the application to which it will be put.Gears can be cast,cut,or extruded.Typical materials include cast iron,cast steel,plain carbon steel,alloy steel aluminum,phosphor bronze,laminated phonetics,and nylon. 中文翻译 齿轮 齿轮是机器中的动力元件 ,用来传递轴与轴之间的运动及动力。它们可能仅被用来传递运动 ,即机器的一个部分到另一个部分 ,或者被用来改变轴与轴之间相对速度和转矩 ,第一个被发现用齿轮的机器是钟表 ,事实上 ,钟表的齿轮与火车上的齿轮相比是非常小的。由于齿轮在实际环境中的广泛应用 ,人们在齿轮的应用方面进行了 许多的研究和调查。现在 ,齿轮传动比起以前来不得不传递很重的载荷 ,和在高速度下运转。目前工程师和机械师都在考虑存在于机械中的这种因素。 直齿圆柱齿轮 直齿圆柱齿轮被作为传动中的首选有许多原因。它们是最简单也是最廉价的，并且它们可以被用作传动平行轴之间的力，还有它的概念同于其它类型的齿轮，以下的几个定义是非常重要的，因为，它们在设计任何与齿轮有关的方面都是非常重要的。 径节 节圆直径单位距离上的齿数，径节通常是一个整数。小小的一段齿距包括了许多的齿形。直齿圆柱齿轮啮合的条件是必须有相同的径节，齿轮的传动比决定于 啮合齿轮的不同的节圆和不同数目的齿数。 齿距 沿着节圆从齿上的一点到临近齿上对应相同的另一点的距离，这是一个线尺寸和线性单位。 节圆 作为齿轮比率设定基础的圆。若要是互相啮合的齿轮正常运行，则两节圆必须精确相切。 压力角 运动方向与垂直于两啮合齿轮中心线的直线所形成的夹角。对于直齿圆柱齿轮压力角为 14.5 度或 20 度，因此可以有许多的用途，相啮合的齿轮必须有相同的压力角。对于齿条，齿相对于直边有与压力角相同的倾斜角度。 基圆 与运动方向相切（或与压力角方向相切）的圆。基圆是产生渐开线所假想的圆。许多直齿圆柱齿 轮都是渐开线从基圆到齿顶，当绷紧绳索从一个圆柱体展开时，仔细观察绳索上某点的运动，即可想象出此段渐开线的形状。在齿轮中，基圆是最主要的圆。 齿顶高 从节圆到齿顶的径向距离。 齿根高 从节