【正文】 時(shí)。圖 顯示了這樣的建筑設(shè)備剖視圖一個(gè)十字架。 英文翻譯原文 MACHINES the manufacture of gear wheels, paratively plicated and highly precise machine tools are required. The wide variety of existing types of machines is the result of the effort made to find economic production methods for the geometrically diverse geartooth forms. The requirements of a gearcutting machine result from the demands that are made by the machine element 39。gear wheel39。, .: (a) high geometric accuracy, notwithstanding the plicated form necessary for the smooth transmission of motion。 (b) high material strength to enable the transmission of large torques with smallsized wheels。 (c) large varieties of design, particularly in the field of smallbatch and 39。one .off39。 production, in order to optimize specialized drive characteristics. Systematic classifications of gearcutting machines can be made from a variety of different standpoints. As a general survey, all techniques for the production of gear wheels are summarized in Fig. . From the aspect of the qualities obtainable, differentiation may be made between roughing and finefinishing processes. In line with the previous chapters, the techniques will be divided into chipproducing and chipless production methods. The chipproducing machines are further subdivided according to the cutting geometry of their cutting tools. In order to achieve an economic production rate, whilst at the same time maintaining a high degree of accuracy of the gears produced, gear cutting is menced with a high cutting speed and fast feed rates. This is then followed with a finishing process. For rough gear cutting, the processes most widely used are those of hobbing, gear shaping and for larger gear wheels, gear planing。 for finishing work, the most widely used technique is that of gear grinding which, in contrast to gear shaving and fine gear rolling, may be carried out after heat treatment on hardened gear wheels. From the point of view of the kinematic action of the machine, gearcutting techniques may be classified as shown in Fig. into form cutting (copying) and gene rating processes. When using the formcutting processes, the tool (milling cutter, end mill, grinding wheel) is made with the contour of the finished tooth space. Each tooth space is individually finished and the gear wheel being cut is then indexed through an angle, depending on the number of teeth to be produced, to allow the next tooth space to be out (singleindexing method). The cutter profile must be of the exact form of the required tooth space, which means that for every setup of a different gear wheel to be cut, a special cutting tool is required. Consequently, this technique is almost exclusively used for the 39。one off39。 manufacture of large gear wheels, or in the mass production of very small gear wheels for the precision engineering using generating methods, the involute is generated as a result of the relative motions between the cutting tool and the gear being cut. This has been achieved through a kinematic coupling between the cutter and the work, normally in the form of a closed gear train. The form of the tooth flank consists of a contour resulting from individual flats produced by the cutting tool. The position of the cutter in relation to the gear being cut may be moved incrementally (indexgene rating technique) or continuously (continuously generating technique). The cutting tool itself has straight flanks and, in contrast to the formcutting process, may be used for a wider range of work of a given module. In order to standardize and reduce the number of tools to be stocked, the basic profile of spur gears is defined by the normal section of a rack (whichmay be regarded as an external gear with an enlarged number of teeth, n →∞ ) and in the ease of bevel gears by the socalled: face gear (consisting of a spur bevel gear resulting from an enlargement of the bevel angle at 90176。).A further subdivision of gearcutting machines may be made in accordance with the type of gear which may be produced on them, which will be discussed in the following sections. The various forms of gears illustrated in Fig. are classified in accordance with the relative position of the axes of rotation of mating gears and require specific gearcutting machines to produce them gears (parallel axes of rotation and rolling action) can have external as well as internal teeth, and these may be straight, helical or doublehelical in gears can have their teeth straight, helical or curved. In the latter ease the lines of the flanks of the teeth may basically follow as involutes or an epicycloids. (The Czechos has a prehensive term “ kot225。lice”). Furthermore the axes of rotation being at right angles to each other may intersect each other (rolling action) or their axes may be relatively displaced (bevelworm drive). Bevel gears are mainly produced by hobbing machines and lapped after heat skew gears are mating cylindrical helical gears, the axes of which are crossed with varying helix angles. The sum of the helix angles of the two gears determines the angle at which the axes cross. Their manufacturing technique does not differ from that of spur order to obtain high gear ratios for axes lying at right angles to each other, cylindrical worm and worm wheel drives or globoidal (hourglass) (Hindey39。s screw) worm and worm wheel drives are applied. Chipforming gearcutting machines using cutters with cutting edges of a critical geometry Gearplaning machines Spur gears When applied to the production of spur gears, gearplaning machines operate in accordance with the indexinggeneration principle in a semicontinuous technique (Fig. )。 this means that as a result of the particular length (number of teeth) of the cutting rack, several tooth spaces are generated before indexing is n