Hull part design - DBE, drawings

Contents

1. Introduction

2. General part

2.1 Analysis of initial data

2.2 Part Specification Analysis

2.3 Part processability analysis

3. Technological part

3.1. Production Volume Calculations and Production Type Determination

3.2. Procurement Selection

3.3 Selection of process bases and procurement processing sequence

3.4 Calculation of machining allowances

3.5 Calculation of cutting modes

3.6 Equipment Selection

3.7 Selection of technological equipment

3.8 Determination of the main process time

4. Design part (fixture design)

4.1 Design Description, Purpose, Principle of Operation

4.2 Calculation of the accessory for accuracy

4.3 Calculation of accessory for clamping force

4.4 Calculation of the device for strength by weak link

4.5 Development of process of accessory assembly

5. Economic part

Part Manufacturing Cost Calculation

Conclusion

Literature

Introduction

The project will consider the Enclosure part.

For the part, a processability analysis will be carried out, which will allow assessing its processability, that is, the possibility of rational processing using standard tools and on existing equipment.

The calculation of the consolidation factor of the operation will allow you to determine the type of production, select the appropriate equipment, the method of obtaining the workpiece and determine the compositions characteristic of this type of production and the sequence of operations.

The design will select the type of accessory, its calculation for accuracy, clamping force and calculation of the weak link of the accessory for strength. A tool assembly route will be developed.

The result of the work will be the design of the process (roadmap, operating map, sketch map, processing route, adjustment) and design documentation (part drawing, accessory assembly drawing) according to AETD and ESKD.

2. General part

2.1 Analysis of initial data.

The body parts of the machines are basic parts, various parts and assembly units are installed on them, the accuracy of which must be ensured during the operation of the machine under load. Accordingly, the body parts shall have the required accuracy, rigidity and vibration resistance.

Reduction gear is intended for transmission of torque from electric motor through elastic clutch to driving shaft with change of rotation speed.

The gearbox housing is designed mainly for placement and coordination in its internal cavity of parts, their protection from contamination, organization of the lubrication system, as well as perception of forces arising in engagement of the gearbox pair and bearings.

The actuating surfaces of the housing and their mutual arrangement shall be made with such a degree of accuracy as to ensure uninterrupted operation of the gearbox throughout its service life in accordance with the technical requirements for the product.

The program of release according to the task is 5000 pcs/year, issue according to unchanged drawings for 5 years.

2.3 Part processability analysis

The main tasks solved in the analysis of the processability of the housing structure are reduced by reducing the time spent on the technological preparation of the production, manufacture of the part.

By studying the hull drawing, you can draw the following conclusions:

1. The highest requirements are for the mutual arrangement of the surfaces of the base of the housing and the axes of the holes for the installation of bearings - a deviation from parallelism of not more than 0.03 mm by a length of 200 mm.

2. High requirements are imposed on the mutual arrangement of axes of cylindrical surfaces with a diameter of 35 and 110 mm - a deviation from coaxiality of not more than 0.05mm.

These are also the most accurate surfaces (Ø35Js7, Ø100Js7).

The roughness of these surfaces is Ra1.6 μm.

To meet these requirements, it is necessary to spread these surfaces in several transitions (rough, semi-pure, finished, thin), to observe the principle of base unity in order to obtain the required amount of alignment and parallelism relative to the base of the housing.

3. High requirements are made for mutual arrangement of axes of mounting holes with diameter 8H7 - tolerance for linear dimensions is not more than 0.02 mm.

4. Requirements for other surfaces are not high. Medium (IT1214) and surface roughness allow to obtain the required surface quality after rough and semi-finished machining with a standard tool.

From the above, it can be concluded that the housing is a relatively workpiece. For its manufacture, the use of special machines and tools is not required, but it will require the manufacture of special devices for processing and control of the resulting deviations.

3.2 Selection of the workpiece.

The method of obtaining workpieces for machine parts is determined by the purpose and design of the part, material, technical requirements, type

production, as well as cost-effectiveness of production. For rational

The procurement selection must take into account all the above source data at the same time, since there is a close relationship between them.

In this case, the material properties are the determining factor. The part is made of cast iron, and it, as is known, is not treatable by pressure, being a brittle material. At the same time, it has good casting properties.

The structure of the procurement selection process, its content is determined by the degree of complexity of the produced procurement and accordingly requires the use of one or more methods for its execution.

First of all, the technological capabilities of the material given by the designer in the drawing of the part, the effect of its alloying degree on workability are considered.

If the material of the part has casting properties and at the same time is well processed by pressure, then the choice of the process and method of manufacturing the workpiece is associated with ensuring a given quality of the part, that is, with the technical condition for manufacturing.

As a result of the analysis, many processes and methods are excluded, the degree of technical perfection of the decisions made is established, possible options are selected, and they are specified.

The structure of the material from which the part is made consists of pearlite with graphite inclusions. Graphite has low mechanical properties compared to steel, but it is thanks to graphite that cast iron has advantages over steel:

- the presence of graphite facilitates machinability by cutting, makes chips brittle (when the cutter reaches graphite inclusion),

- cast iron has good antifriction properties, the presence of graphite inclusions quickly extinguishes vibrations and resonant oscillations ,

- Cast iron is almost insensitive to surface defects, incisions, etc.

The low melting point and the end of crystallization at a constant temperature (eutectic formation) provide not only convenience in operation, but also good fluid flow and occupancy of the mold. The described properties of cast iron make it a valuable structural material widely used in machine parts, mainly when they do not experience significant tensile and impact loads.

The casting method should ensure high performance of the cast product, high technical and economic displays of production. When choosing the casting method, the following are taken into account: the type of alloy and its casting properties, the service purpose and design of the part, technical requirements, serial production.

Therefore, the workpiece for the part is obtained by casting into a chill.

Coquille is a metal mold that is filled with melt under the influence of gravitational forces. Unlike the one-time sandy form, coquille can be used many times. Thus, the essence of co-casting consists in the use of metal materials for the manufacture of reusable molds, the metal parts of which form their basis and form the configuration and properties of the casting.

Coquille usually consists of two half-molds, a plate, inserts. Half-molds are mutually centered with pins, and before filling they are connected with locks. Dimensions of working cavity of chill are more than dimensions of casting by value of alloy shrinkage. Cavities and holes in casting can be made with metal or sand rods, which are removed from casting after its solidification and cooling to preset temperature. The melt is poured into a co-keel through a runner system made in its walls, and the massive casting units are fed from profits (feed blasts).

When the chill is filled with melt, air and gases are removed from its working cavity through the chill ventilation system.

The main elements of the coquille - half-molds, plates, inserts, rods, etc. - are usually made of heat-resistant steel.

Main process operations. Before filling the melt, a new chill is prepared for operation: the surface of the working cavity and the connector are thoroughly cleaned from traces of contamination, rust, oil; easy movement of movable parts, accuracy of their alignment and reliability of attachment are checked. Then layer of refractory coating of lining and paint is applied on surface of working cavity and metal rods. The co-formation of linings and paints depends mainly on the poured alloy, and their thickness depends on the required cooling rate of the casting: the thicker the layer of fire-thrust coating, the slower the casting is cooled. At the same time, the refractory coating layer protects the working surface of the mold from a sharp increase in its temperature during pouring, melting and setting with the casting metal. Thus, linings and paints perform two functions: they protect the surface of the chill from sharp heating and setting with casting and allow you to control the cooling rate of the casting, and therefore the processes of its solidification that affect the properties of the casting metal. Prior to application of the refractory coating, the chill is heated with gas burners or electric heaters to a temperature of 423-453 K. The paints are applied to the co-keel usually as an aqueous suspension through a spray gun. The water slurry droplets on the surface of the heated chill evaporate and the fire-resistant component coats the surface with an even layer.

After application of refractory coating, chill is heated to working temperature depending mainly on composition of poured alloy, thickness of casting wall, its dimensions, required properties. Typically, the heating temperature of the chill before pouring 473-623 K. Then, sand, ceramic or metal rods, if necessary for casting, are installed in the chill; halves of the coquille are connected and fastened with special clamps, and when installing the coquille on the coquille machine using its locking mechanism, after which the melt is poured into the coquille. Often, during solidification and cooling of the casting, after the casting has acquired sufficient strength, the metal rods are < blown >, i.e. partially removed from the casting before it is removed from the chill. This is done in order to reduce the reduction of the shrinkable cast metal rod and to ensure its removal from the cast. After the casting is cooled to a given temperature, the chill is opened, the metal rod is finally removed and the casting is removed from the chill. Rod is knocked out of casting, gates are trimmed, profits, bulges, quality of casting is controlled. The cycle is then repeated.

As you can see, the process of casting into a chill is low-operational. Manipulative operations are quite simple and short-term, and the limiting operation is the cooling of the mold casting to a given temperature. Almost all operations can be carried out by machine mechanisms or automatic installation, which is a significant advantage of the method, and, of course, the most important thing is that the labor-intensive and material-intensive process of making a mold is excluded: the chill is used many times.

Peculiarities of forming and quality of castings. Coquille is a metallic form that has significantly greater thermal conductivity, heat capacity, strength, almost zero gas permeability and gas permeability compared to sand. These properties of the choyl material give rise to the following features of its interaction with the casting metal.

1. High efficiency of thermal interaction between casting and mold: melt and solidifying casting are cooled in coquila faster than in sand form, i.e. at the same hydrostatic head and temperature of the poured melt, the occupancy of the coquille is usually worse than the sand form. This complicates the production of low-fluid alloy castings in the coke and limits the minimum wall thickness and size of the castings. At the same time, the increased cooling rate contributes to the production of dense castings with a fine grain structure, which increases the strength and ductility of the metal of the castings. However, in cast iron castings obtained in cokels, due to crystallization features, carbides, ferritographic eutectics are often formed that negatively affect the properties of cast iron: toughness, wear resistance are reduced, hardness in the bleached surface layer increases sharply, which makes it difficult to cut such castings and leads to the need to undergo heat treatment (annealing) to eliminate bleaching.

2. Coquille is practically impenetrable in more intensively prevents shrinkage of the casting, which makes it difficult to remove it from the mold, can cause internal stresses, warping and cracks in the casting.

However, the dimensions of the working cavity of the chill can be made much more precisely than the sand shape. When casting into a chill, there are no errors caused by the model pushing, elastic and residual deformations of the sand mold, which reduce the accuracy of its working cavity and, accordingly, casting. Therefore, castings in cokils are more accurate. The accuracy of castings in cockles usually corresponds to 12-15th squares. At the same time, accuracy according to the 12th quota is possible for sizes located in one part of the mold. The accuracy of the dimensions located in two or more parts of the mold, as well as those formed by the movable parts of the mold, is lower. The accuracy factor of the castings by weight reaches 0.71, which makes it possible to reduce the allowance for cutting treatment.

3. The physical and chemical interaction of the casting metal and the chill is minimal, which contributes to improving the quality of the casting surface. Castings in a chill do not have a bow. Surface roughness of castings is determined by compositions of linings and paints applied to the surface of the working cavity of the mold, and corresponds to Rz = 8018 μm, but can be smaller.

4. The chill is practically gas-tight, but its gasification is minimal and is determined mainly by the compositions of refractory coatings applied to the surface of the working space. However, gas shells in coke castings are not uncommon. The reasons for their occurrence are different, but in any case the arrangement of the casting in the mold, the method of supplying the melt and the ventilation system should ensure the removal of air and gases from the chill during pouring.

Production efficiency and application. The efficiency of production of castings into a chill, as well as other casting methods, depends on how fully and correctly the casting engineer takes advantage of this process, takes into account its peculiarities and disadvantages and conditions of a particular production. The following are advantages of casting into a chill based on production experience.

1. Increase of labor productivity as a result of exclusion of labor-intensive operations of mixing, moulding, cleaning of castings from burning. Therefore, the use of casting in kokili, according to various enterprises, allows you to increase labor productivity in the foundry by 2-3 times, reduce capital costs during the construction of new workshops and the reconstruction of existing ones by reducing the required production areas, equipment costs, treatment facilities, and increase the removal of castings from 1 m2 of workshop area.

2. Improvement of casting quality due to use of metal mold, improvement of stability of quality indicators: mechanical properties, structure, density, roughness, accuracy of casting dimensions.

3. Elimination or reduction of the volume of harmful to health operations of molds knocking out, cleaning castings from burning, their cutting, general improvement and improvement of working conditions, less pollution of the environment.

4. Mechanization and automation of the casting process due to the reusability of the chill. To obtain castings of a given quality, it is easier to carry out automatic control of process parameters. Automation of the process allows improving the quality of castings, increasing production efficiency, changing the nature of the work of the foundry operator managing the operation of such complexes.

Disadvantages of coquille casting:

1. High cost of coquille, complexity and labor intensity of its manufacture.

2. The limited resistance of the coquille as measured by the number of suitable castings that can be obtained in the coquile. The economic efficiency of the process depends on the stability of the chill.

3. The difficulty of obtaining castings with undercuts, for which it is necessary to complicate the design of the mold - to make additional connectors, to use inserts, detachable metal or sand rods.

4. improper chill leads to stresses in castings, and sometimes to cracks.

This casting method is usually used in mass production and mass production.

The efficiency of coquille casting is usually determined in comparison with sand casting. Economic effect is achieved due to elimination of moulding mixture, improvement of quality of castings, their accuracy, reduction of allowance for processing, reduction of labour intensity of cleaning and blowing of castings, mechanization and automation of main operations and, as a result, increase of productivity and improvement of working conditions.

Casting into a chill should be referred to as labor and material-saving, small-operation and low-waste technological processes that improve working conditions in foundries and reduce the harmful impact on the environment.

The workpiece drawing is designed in accordance with the requirements

GOST 3.112585.

Technical requirements for casting:

1. Casting of accuracy class 1212 as per GOST 2664585.

2. Permissible displacement of supports is not more than 0.5 mm.

3. Minimum value of fillet radii R3 + 2.

4. Moulding slopes are not more than 3 °.

5. Clean the casting surface from scale.

6. Surface defects of surfaces up to 0.3% of allowance are allowed.