COURSEWORK in the discipline "Standardization of accuracy in mechanical engineering"
- Added: 14.01.2020
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1. Description of assembly unit. The pump reducer is a special mechanism whose main function is to convert mechanical energy into hydraulic energy, which in turn can be used in hydraulic winches, hydraulic rotors for drilling oil wells. The use of a pump reduction gear makes it possible to significantly reduce the number of cardan shafts in the design of the well repair unit for transmitting torque to the rotor. The ability to control the rotor or winch remotely, position them in any convenient place. Also, the advantages that the pump reduction gear has include its ability to convert hydraulic energy into mechanical energy, that is, hydraulic motors can be installed instead of a hydraulic pump. We define limit dimensions of holes and shafts, tolerance for holes and shafts by formulas.
1. Description of assembly unit
2. Defining Gaps and Interference in a Smooth Cylindrical Joint
3. Calculation of limit gauges
4. Justification of selection of rolling bearings fits on shafts and in holes of housings
5. Calculation of threaded joint fits
6. Calculation and selection of fits on splined joints with straight and involute profile
List of literature
In the course of development of a product (the car, the unit, knot) it is necessary to proceed from the set level of standardization and unification which is defined by coefficients of applicability, repeatability and interdesign unification. With an increase in the values of these coefficients, the economic efficiency of the developed product during its production and operation increases. To improve standardization and harmonization, it is necessary, already at the stage of product design, to use a larger number of industrial components and strive to reasonably limit the development of original components. At the same time, the main issue in the development process is the accuracy of interchangeable parts, assemblies and components, primarily in terms of geometric parameters.
Interchangeability of parts, assemblies and assemblies allows aggregation, as one of the methods of standardization, to organize the supply of spare parts, to facilitate repair, especially in difficult conditions, reducing it to simple replacement of worn parts.
Interchangeability - the property of independently manufactured parts to take its place in the assembly unit without additional mechanical or manual processing during assembly, while ensuring the normal operation of the assembled products (assemblies, mechanisms).
From the very definition of interchangeability, it follows that it is a prerequisite for the dismemberment of production, i.e. independent production of details, knots, units which in the subsequent gather consistently in assembly units, and assembly units - in the general system (mechanism, the machine, the device). Assembly can be conducted in two ways: with adjustment and without adjustment of the collected details or assembly units. Assembly without fitting is used in mass and in-line production, and with fitting - in single and small-scale production. Parts shall be manufactured with the necessary accuracy during assembly without fitting. However, interchangeability is not provided by the accuracy of geometric parameters alone. It is necessary that the material, durability of parts, assemblies and components is agreed with the purpose and working conditions of the final product. Such interchangeability is called functional, and interchangeability by geometric parameters is a particular type of functional interchangeability. Interchangeability is complete and incomplete, external and internal.
Full interchangeability allows you to obtain specified quality indicators without additional operations during the assembly process.
In case of incomplete interchangeability during assembly of assembly units and final products, operations related to selection and adjustment of some parts and assembly units are allowed. It allows you to obtain the specified technical and operational indicators of the finished product with less accuracy of the parts. At the same time, functional interchangeability should be only complete, and geometric - both complete and incomplete.
External interchangeability is interchangeability of units and components according to operational parameters and connection dimensions. For example, replacing an electric motor. Its operational parameters will be - power, speed, voltage, current; connection dimensions include diameters, number and arrangement of holes in the legs of the electric motor, etc.
Internal interchangeability is ensured by the accuracy of the parameters that are required to assemble parts into assemblies, and assemblies into mechanisms. For example, interchangeability of ball bearings or rollers of rolling bearings, units of drive and driven shafts of gearbox, etc.
The principles of interchangeability apply to parts, assemblies, components and final products.
As a result of the work done, theoretical material was studied, as well as practical tasks were completed on the following topics:
Tolerances and fits of smooth cylindrical joints. Selection of measuring instruments.
Calculation and design of limit gauges for connection control.
Normalizes the accuracy of the part included in the assembly.
As a result of completing the tasks, he learned to work with standards, mastered the methods of normalizing the accuracy of connection of various types.
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