Front axle wheels GAZ-66 - diploma project

Introduction

A modern car is a complex machine, consisting of a number of systems, assemblies and assemblies that contain thousands of parts. As the main type of ground rail-free transport, cars operate in a wide variety of road, climatic and other operating conditions.

The variety of operating conditions and complexity of the design determined the need to use a whole range of operational properties to assess the possibility and convenience of the transport process by the car in specific conditions with a certain productivity, economy and profitability. The main operational properties of the car are associated with its movement. They are determined by parameters and output characteristics of systems, units and units. The level of these parameters is ensured during the design and production process and depends on the technical condition of the car during operation.

With long-term operation, the technical condition of the car, like any car, inevitably deteriorates. Maintaining the vehicle in operable condition during long-term operation is the main task of maintenance and repair.

The technical condition of cars or their units and parts is qualitatively divided into serviceable - faulty, operable - inoperable and marginal. In the regulatory and technical documentation, the required limits of parameter values characterizing the quality of work of structural elements are established. Non-compliance of the car with at least one of the established requirements indicates the damage that occurred, that is, the transition from a serviceable state to a faulty one. If the parameter characterizing the ability of the car to perform the specified functions - to perform transport work does not meet the requirements, this means that there was a failure - a malfunction, and the car is not operational .

Units and most parts of the car are repaired objects, their serviceability and operability in case of failure or damage should be restored. In the extreme case of operability, when the operation of the car or its unit must be stopped or it must be overhauled, the condition of the object is called limit. It should be noted that the limit state of the various units of the car is determined by both an irreparable violation of traffic safety and an irreparable deviation of the given parameters from the set limits, and mainly by an irreparable decrease in the efficiency of the car. The laws of transitions of technical state of parts, units and systems of a car from a serviceable, operable state to a faulty, inoperable and, finally, to a limit state and back are studied by methods of reliability theory of technical objects. When analyzing reliability, a car, its system, unit or part is considered as a separate technical object.

Reliability is the property of an object to maintain in time within the established limits the values ​ ​ of all parameters that characterize the ability to perform the required functions in the specified modes and conditions of use, maintenance, repairs, storage and transportation. Reliability is a complex property of a technical object, which is for the car and most of it

units include reliability, durability, repairability and persistence. For parts and from individual units, reliability includes one of the specified properties or a certain combination of them. Quantitative characterization of reliability properties is performed

reliability indicators, which are called single or complex depending on whether they evaluate one or more reliability properties. Reliability indicators are considered depending on the duration of the car - the operating time, which is measured in thousands of kilometers of mileage or hours of work.

The reliability of the car is its property to continuously remain operational for some time or some mileage. When analyzing the reliability of car units and systems, a classification of failures is always carried out depending on the direction of management decisions, for which analysis is carried out. Failure of a separate structural element in some cases may not cause a failure of the unit, and in others, cause a partial or complete failure of the unit, system and car as a whole. In case of partial failure, for example, failure of the brake drive of the front wheels of a car with a separate brake drive of bridges, the system remains operational, but works with much lower efficiency. When classifying failures, they consider the criterion, causes, signs, nature and consequences of malfunction.

Criteria and signs of failures are specified in the regulatory and technical documentation (level of tire tread wear, engine oil consumption, etc.) and are detected by measurement using instruments or direct observation (certain noise during unit operation, smoke, increased heating, etc.). The causes of failures may be defects committed during design, production and repair, as well as violation of rules and standards of operation, in accordance with which failures are divided into structural, production and operational. During long-term operation of cars, most failures are caused by various types of damage and natural processes of wear and aging, the rate of growth of which depends on the quality of maintenance.

1. General position of the front axle wheel mechanism of GAZ 66.

1.1 Service purpose and technical characteristics of the vehicle unit or assembly.

Front axle transmits traction force to front controlled wheels. For this purpose, in addition to the main gear and differential, a special cardan hinge is installed in the front axle. The need to use such a hinge is caused by large rotation angles of the front wheels (up to 30 °). At such angles between shafts with conventional hinges, uneven rotation of the shafts occurs and, as a result, large dynamic loads. Used in the front axle of the car GAZ66, a cardan hinge of equal angular speed provides the same rotation speed of the shafts regardless of the angle between them. In this hinge, the torque is transmitted not by a cross, as in ordinary gimbals, but by balls.

The main gear and differential of the front axle are unified.

4.2. Process diagram of assembly of the assembly and individual assemblies.

Process diagrams of the assembly reflect the structure and order of picking the product and its components; they simplify the development of assembly processes and make it possible to evaluate the processability of the product design in terms of the completeness of maintaining the principle of knot assembly.

The assembly flow chart of the assembly is shown in. Each element of the product is conventionally indicated on the diagram by a rectangle divided into three parts. The top part indicates the name of the element, the bottom left part indicates its index, and the bottom right indicates the number of elements to collect. Feature indexes correspond to part and subassembly numbers in drawings and schedules.

Preparation of process diagrams for assembly of the assembly is possible in several versions, differing both in structure and in sequence of assembly elements collection. The choice is made taking into account the performance, profitability and convenience of assembly.

5. Development of technological tooling.

The developed accessory is designed for processing the keyway on the Model 6P81 horizontal-milling machine.

The structure of the accessory consists of:

- support elements in the form of permanent support prisms;

- a clamping device including a contact element in the form of a prism connected to the plate by screws and pins, a conductor plate connected to the base and the housing by means of a pneumatic chamber bushing actuated by turning the crane handle;

- elements ensuring accurate arrangement of the device on the machine in the form of a key guide;

- base made by welding of elements cut from steel rolled stock.

6.2.3 Protection against noise, vibration and ultrasound.

Vibration is the movement of a point or mechanical system in which values ​ ​ of at least one coordinate increase and decrease alternately in time.

Effects of vibration on the human body. The human body is considered as a combination of masses with elastic elements having their own frequencies, which for the shoulder belt, hips and head relative to the supporting surface (standing position) are 4-9 Hz, the head relative to the shoulders (sitting position) is 2530 Hz. For most internal organs, the natural frequencies lie in the range of 4-9 Hz.

The weight of the vibrating equipment or parts thereof held by the hands shall not exceed 10 kg and the pressing force shall not exceed 20 kg.

The total vibration is normalized taking into account the properties of the source of its occurrence and is divided into vibration:

♦ transport which results from the movement of cars on the area and roads;

♦ transport-technological, which occurs during the operation of machines performing a technological operation in a stationary position, as well as when moving through a specially prepared part of the production room, industrial site or at wholesale bases;

♦ technological, which occurs during the operation of stationary machines or is transferred to workplaces that do not have sources of vibration (for example, from the operation of refrigeration, packing and packaging machines).

In this area the vibration is in the required norms of 2025 Hz.

Methods to reduce vibration of machines and equipment. The causes of vibration may be incorrect installation and operation of machines and equipment, unequal wear and tear of individual units.

The main methods of vibration control:

♦ reducing vibrations by affecting the excitation source by reducing or eliminating inducing forces;

♦ elimination of the mode of a resonance by means of the rational choice of weight or rigidity of the fluctuating system;

♦ dynamically dampening vibrations by connecting a vibration source to a protective object that reduces vibration swing;

♦ Change the structural elements of machines and time-personal constructions.

Noise is a hygienic factor that is a combination of sounds that adversely affect the human body, interfere with its work and rest.

The entire noise range fits within the limits of 13... 14 B. For convenience, they use not white, but a unit 10 times smaller - decibell (dB), which corresponds to the minimum increase in sound strength distinguished by the ear.

Noise in this area is 80 dB

The effect of noise on the human body. This short-term reduction of hearing acuity under the influence of noise with a rapid restoration of function after the termination of the factor is considered as a manifestation of the adaptive protective-adaptive response of the auditory organ. Adaptation to noise is considered to be a temporary reduction in hearing by no more than 10-15 dB with its restoration within 3 minutes after the cessation of noise. Prolonged exposure to intense noise can lead to re-irritation of the cells of the sound analyzer and its fatigue, and then to a persistent decrease in hearing acuity.

The effect of noise can lead to diseases of the ventricular intestinal tract, shifts in metabolic processes (violation of the main, vitamin, carbohydrate, protein, fat, salt metabolism), violation of the functional state of the cardiovascular system.

Noise control techniques. To combat noise in the premises, measures of both technical and medical nature are carried out. The main ones are:

♦ elimination of the cause of noise or its significant attenuation in the source itself during the development of technological processes and

♦ equipment design;

♦ isolation of the noise source from the environment by means of sound and vibration protection, sound and vibration absorption;

♦

♦ reduced density of sound energy of rooms reflected from

♦ of walls and floors;

♦ rational layout of premises;

♦ application of personal noise protection equipment;

♦ rationalization of the mode of work in the conditions of noise;

♦ Preventive medical measures.

The most effective way to combat noise, which is caused by vibration arising from shocks, friction forces, mechanical forces, etc., is to improve the design of the equipment (changing the technology to eliminate the impact).

In this area, sound and vibration insulation ceilings are used to reduce structural noise propagated in solid media. Noise attenuation is achieved by using elastic gaskets under the floor without their rigid connection with load-bearing structures of buildings, installation of vibrating equipment on shock absorbers or special isolated foundations. Soundproofing of the site occurs using sound absorption means. For this room (500-1000 m3), the general lining of walls and floors is used, reducing the noise level by 7-8 dB.

Also in this area, the reduction of the negative effect of noise occurs by reducing the time of their impact and building a rational mode of work and rest, which provides short breaks during the working day to restore the function of hearing in quiet rooms.