2023年机械专业英文翻译.docx

2023年机械专业英文翻译 Design of machine and machine elements Machine design Machine design is the art of planning or devising new or improved machines to accomplish specific purposes.In general, a machine will consist of a combination of several different mechanical elements properly designed and arranged to work together, as a whole.During the initial planning of a machine, fundamental decisions must be made concerning loading, type of kinematic elements to be used, and correct utilization of the properties of engineering materials.Economic considerations are usually of prime importance when the design of new machinery is undertaken.In general, the lowest over-all costs are designed.Consideration should be given not only to the cost of design, manufacture the neceary safety features and be of pleasing external appearance. The objective is to produce a machine which is not only sufficiently rugged to function properly for a reasonable life, but is at the same time cheap enough to be economically feasible. The engineer in charge of the design of a machine should not only have adequate technical training, but must be a man of sound judgment and wide experience, qualities which are usually acquired only after considerable time has been spent in actual profeional work.Design of machine elements The principles of design are, of course, universal.The same theory or equations may be applied to a very small part, as in an instrument, or, to a larger but similar part used in a piece of heavy equipment.In no ease, however, should mathematical calculations be looked upon as absolute and final.They are all subject to the accuracy of the various aumptions, which must necearily be made in engineering work.Sometimes only a portion of the total number of parts in a machine are designed on the basis of analytic calculations.The form and size of the remaining parts are designed on the basis of analytic calculations.On the other hand, if the machine is very expensive, or if weight is a factor, as in airplanes, design computations may then be made for almost all the parts. The purpose of the design calculations is, of course, to attempt to predict the stre or deformation in the part in order that it may sagely carry the loads, which will be imposed on it, and that it may last for the expected life of the machine.All calculations are, of course, dependent on the physical properties of the construction materials as determined by laboratory tests.A rational method of design attempts to take the results of relatively simple and fundamental tests such as tension, compreion, torsion, and fatigue and apply them to all the complicated and involved situations encountered in present-day machinery. In addition, it has been amply proved that such details as surface condition, fillets, notches, manufacturing tolerances, and heat treatment have a market effect on the strength and useful life of a machine part.The design and drafting departments must specify completely all such particulars, must specify completely all such particulars, and thus exercise the neceary close control over the finished product. As mentioned above, machine design is a vast field of engineering technology.As such, it begins with the conception of an idea and follows through the various phases of design analysis, manufacturing, marketing and consumerism.The following is a list of the major areas of consideration in the general field of machine design: Initial design conception; Strength analysis; Materials selection; Appearance; Manufacturing; Safety; Environment effects; Reliability and life; Strength is a measure of the ability to resist, without fails, forces which cause strees and strains.The forces may be; Gradually applied; Suddenly applied; 2 Applied under impact; Applied with continuous direction reversals; Applied at low or elevated temperatures. If a critical part of a machine fails, the whole machine must be shut down until a repair is made.Thus, when designing a new machine, it is extremely important that critical parts be made strong enough to prevent failure.The designer should determine as precisely as poible the nature, magnitude, direction and point of application of all forces.Machine design is mot, however, an exact science and it is, therefore, rarely poible to determine exactly all the applied forces.In addition, different samples of a specified material will exhibit somewhat different abilities to resist loads, temperatures and other environment conditions.In spite of this, design calculations based on appropriate aumptions are invaluable in the proper design of machine. Moreover, it is absolutely eential that a design engineer knows how and why parts fail so that reliable machines which require minimum maintenance can be designed.Sometimes, a failure can be serious, such as when a tire blows out on an automobile traveling at high speeds.On the other hand, a failure may be no more than a nuisance.An example is the loosening of the radiator hose in the automobile cooling system.The consequence of this latter failure is usually the lo of some radiator coolant, a condition which is readily detected and corrected. The type of load a part absorbs is just as significant as the magnitude.Generally speaking, dynamic loads with direction reversals cause greater difficulties than static loads and, therefore, fatigue strength must be considered.Another concern is whether the material is ductile or brittle.For example, brittle materials are considered to be unacceptable where fatigue is involved. In general, the design engineer must consider all poible modes of failure, which include the following: Stre; Deformation; 3 Wear; Corrosion; Vibration; Environmental damage; Loosening of fastening devices. The part sizes and shapes selected must also take into account many dimensional factors which produce external load effects such as geometric discontinuities, residual strees due to forming of desired contours, and the application of interference fit joint. Selected from” design of machine elements”, 6th edition, m.f.sports, prentice-hall, inc., 1985 and “machine design”, Anthony Esposito, charles e., Merrill publishing company, 1975. Quality aurance and control Product quality is of paramount importance in manufacturing.If quality is allowed deteriorate, then a manufacturer will soon find sales dropping off followed by a poible busine failure.Customers expect quality in the products they buy, and if a manufacturer expects to establish and maintain a name in the busine, quality control and aurance functions must be established and maintained before, throughout, and after the production proce.Generally speaking, quality aurance encompaes all activities aimed at maintaining quality, including quality control.Quality aurance can be divided into three major areas.These include the following: Source and receiving inspection before manufacturing; In-proce quality control during manufacturing; Quality aurance after manufacturing. Quality control after manufacture includes warranties and product service extended to the users of the product. Source and receiving inspection before manufacturing Quality aurance often begins ling before any actual manufacturing takes place.This may be done through source inspections conducted at the plants that supply materials, discrete parts, or subaemblies to manufacturer.The manufacturers source inspector travels to the supplier factory and inspects raw material or premanufactured parts and aemblies.Source inspections present an opportunity for the manufacturer to sort out and reject raw materials or parts before they are shipped to the manufacturers production facility. The responsibility of the source inspector is to check materials and parts against design specifications and to reject the item if specifications are not met.Source inspections may include many of the same inspections that will be used during production.Included in these are: Visual inspection; Metallurgical testing; Dimensional inspection; Destructive and nondestructive inspection; Performance inspection.Visual inspections Visual inspections examine a product or material for such specifications as color, texture, surface finish, or overall appearance of an aembly to determine if there are any obvious deletions of major parts or hardware. Metallurgical testing Metallurgical testing is often an important part of source inspection, especially if the primary raw material for manufacturing is stock metal such as bar stock or structural materials.Metals testing can involve all the major types of inspections including visual, chemical, spectrographic, and mechanical, which include hardne, tensile, shear, compreion, and spectr5ographic analysis for alloy content.Metallurgical testing can be either destructive or nondestructive. Dimensional inspection Few areas of quality control are as important in manufactured products as dimensional requirements.Dimensions are as important in source inspection as they are in the manufacturing proce.This is especially critical if the source supplies parts for an aembly.Dimensions are inspected at the source factory using standard measuring tools plus special fit, form, and function gages that may required.Meeting dimensional specifications is critical to interchangeability of manufactured parts and to the succeful aembly of many parts into complex aemblies such as autos, ships, aircraft, and other multipart products. Destructive and nondestructive inspection In some cases it may be neceary for the source inspections to call for destructive or nondestructive tests on raw materials or p0arts and aemblies.This is particularly true when large amounts of stock raw materials are involved.For example it may be neceary to inspect castings for flaws by radiographic, magnetic particle, or dye penetrant techniques before they are shipped to the manufacturer for final machining.Specifications calling for burn-in time for electronics or endurance run tests for mechanical components are further examples of nondestructive tests. It is sometimes neceary to test material and parts to destruction, but because of the costs and time involved destructive testing is avoided whenever poible.Examples include preure tests to determine if safety factors are adequate in the design.Destructive tests are probably more frequent in the testing of prototype designs than in routine inspection of raw material or parts.Once design specifications are known to be met in regard to the strength of materials, it is often not neceary to test further parts to destruction unle they are genuinely suspect. Performance inspection Performance inspections involve checking the function of aemblies, especially those of complex mechanical systems, prior to installation in other products.Examples include electronic equipment subcomponents, aircraft and auto engines, pumps, valves, and other mechanical systems requiring performance evaluation prior to their shipment and final installation. Selected form “modern materials and manufacturing proce” Electro-hydraulic drum brakes Application The YWW series electro-hydraulic brake is a normally closed brake, suitable for horizontal mounting.It is mainly used in portal cranes, bucket stacker/reclaimersslewing mechanism.The YKW series electro-hydraulic brake is a normally opened brake, suitable for horizontal mounting, employing a thruster as actuator.with the foot controlling switch the operator can release or close the brake.It is mainly used for deceleration braking of portal cranesslewing mechanism.In a non-operating state the machinery can be braked by a manual close device.The RKW series brake is a normally opened brake, which is operated by foot driven hydraulic pump, suitable for horizontal mounting.Mainly used in the slewing mechanism of middle and small portal cranes.When needed, the brake is activated by a manual closed device. Main design features Interlocking shoes balancing devices (patented technology) constantly equalizes the clearance of brake shoes on both sides and made adjustment unneceary, thus avoiding one side of the brake lining sticking to the brake wheel.The brake is equipped with a shoed autoaligning device.Main hinge points are equipped with self-lubricating bearing, making high efficiency of transmiion, long service life.Lubricating is unneceary during operation.Adjustable bracket ensure the brake works well.The brake spring is arranged inside a square tube and a surveyors rod is placed on one side.It is easy to read braking torque value and avoid measuring and computing.Brake lining is of card whole-piece shaping structure, easy to replace.Brake linings of various materials such as half-metal (non-asbestos) hard and half-hard, soft (including asbestos) substance are available for customers to choose. All adopt the companys new types of thruster as corollary equipment which work accurately and have long life. Hydraulic Power Transmiion The Two Types Of Power Transmiion In hydraulic power transmiion the apparatus (pump) used for conversion of the mechanical (or electrical,thermal) energy to hydraulic energy is arranged on the input of the kinematic chain ,and the apparatus (motor) used for conversion of the hydraulic energy to mechanical energy is arranged on the output (fig.2-1) The theoretical design of the energy converters depends on the component of the bernouilli equation to be used for hydraulic power transmiion. In systerms where, mainly, hydrostatic preure is utilized, displacement (hydrostatic) pumps and motors are used, while in those where the hydrodynamic preure is utilized is utilized gor power transmiion hydrodynamic energy converters (e.g.centrifugal pumps) are used. The specific characteristic of the energy converters is the weight required for transmiion of unit power.It can be demonstrated that the use of hydrostatic energy converters for the low and medium powers, and of hydrodynamic energy converters of high power are more favorite (fig.2-2).This is the main reason why hydrostatic energy converters are used in industrial apparatus.transformation of the energy in hydraulic transmiion. 1.2.3.4.5.6.7.driving motor (electric, diesel engine); mechanical energy; pump; hydraulic energy; hydraulic motor; mechanical energy; load variation of the ma per unit power in hydrostatic and hydrodynamic energy converters 1、hydrostatic; 2.hydrodynamic Only displacement energy converters are dealt with in the following.The elements performing converters provide one or several size.Expansion of the working chambers in a pump is produced by the external energy admitted, and