y315滾齒機總體設計畢業設計-資料下載頁

【導讀】床身、大立柱、工作臺、小立柱、傳動箱、刀架等幾部分組成。其床身為箱體結構，臺殼體置于其上，可以沿導軌做直線運動。大立柱堅固在床身的左上方，刀架滑板裝。適當位置，當進刀到位撞下擋塊時，可使機床自動停車。計計算進行了介紹。主要工作有一下幾個方面：

　　

【正文】 that the resulting stresses will be safe. But by no means should the designer assume that they are safe。 it is almost always necessary to calculate them so that he knows they are within acceptable limits. Whenever possible, the powertransmission elements, such as gears or pullets, should be located close to the supporting bearings, This reduces the bending moment, and hence the deflection and bending stress. Although the von MisesHenckyGoodman method is difficult to use in design of shaft, it probably es closest to predicting actual failure. Thus it is a good way of checking a shaft that has already been designed or of discovering why a particular shaft has failed in service. Furthermore, there are a considerable number of shaftdesign problems in which the dimension are pretty well limited by other considerations, such as rigidity, and it is only necessary for the designer to discover something about the fillet sizes, heattreatment, and surface finish and whether or not shot peening is necessary in order to achieve the required life and reliability. Because of the similarity of their functions, clutches and brakes are treated together. In a simplified dynamic representation of a friction clutch, or brake, two inertias I1 and I2 traveling at the respective angular velocities W1 and W2, one of which may be zero in the case of brake, are to be brought to the same speed by engaging the clutch or brake. Slippage occurs because the two elements are running at different speeds and energy is dissipated 本科畢業設計（論文）說明書 25 during actuation, resulting in a temperature rise. In analyzing the performance of these devices we shall be interested in the actuating force, the torque transmitted, the energy loss and the temperature rise. The torque transmitted is related to the actuating force, the coefficient of friction, and the geometry of the clutch or brake. This is problem in static, which will have to be studied separately for eath geometric configuration. However, temperature rise is related to energy loss and can be studied without regard to the type of brake or clutch because the geometry of interest is the heatdissipating surfaces. The various types of clutches and brakes may be classified as fllows: 1. Rim type with internally expanding shoes 2. Rim type with externally contracting shoes 3. Band type 4. Disk or axial type 5. Cone type 6. Miscellaneous type The analysis of all type of friction clutches and brakes use the same general procedure. The following step are necessary: 1. Assume or determine the distribution of pressure on the frictional surfaces. 2. Find a relation between the maximum pressure and the pressure at any point 3. Apply the condition of statical equilibrium to find (a) the actuating force, (b) the torque, and (c) the support reactions. Miscellaneous clutches include several types, such as the positivecontact clutches, overloadrelease clutches, overrunning clutches, magic fluid clutches, and others. A positivecontact clutch consists of a shift lever and two jaws. The greatest differences between the various types of positive clutches are concerned with the design of the jaws. To provide a longer period of time for shift action during engagement, the jaws may be ratchetshaped, or geartoothshaped. Sometimes a great many teeth or jaws are used, and they may be cut either circumferentially, so that they engage by cylindrical mating, or on the 本科畢業設計（論文）說明書 26 faces of the mating elements. Although positive clutches are not used to the extent of the frictionalcontact type, they do have important applications where synchronous operation is required. Devices such as linear drives or motoroperated screw drivers must run to definite limit and then e to a stop. An overloadrelease type of clutch is required for these applications. These clutches are usually springloaded so as to release at a predetermined toque. The clicking sound which is heard when the overload point is reached is considered to be a desirable signal. An overrunning clutch or coupling permits the driven member of a machine to “freewheel” or “overrun” because the driver is stopped or because another source of power increase the speed of the driven. This type of clutch usually uses rollers or balls mounted between an outer sleeve and an inner member having flats machined around the periphery. Driving action is obtained by wedging the rollers between the sleeve and the flats. The clutch is therefore equivalent to a pawl and ratchet with an infinite number of teeth. Magic fluid clutch or brake is a relatively new development which has two parallel magic plates. Between these plates is a lubricated magic powder mixture. An electromagic coil is inserted somewhere in the magic circuit. By varying the excitation to this coil, the shearing strength of the magic fluid mixture may be accurately controlled. Thus any condition from a full slip to a frozen lockup may be obtained.