TLP Exchange Rate Project

Contents

Contents

1. Design Drawing Analysis

1.1. Purpose and working conditions

1.2. Workability of the part

1.3 Technical Requirements for Casting

1.4 Choice of Casting Method

2. Development of casting and model guidelines (LMU)

2.1Mould casting position

2.2Selecting Model and Shape Parting Plane

2.3Define machining allowance

2.4 Determination of number of rods

2.5 Construction of rod signs

2.6 Profit Calculation and Design

2.7 Runner System Calculation

3. Selection and preparation of moulding mixtures

3.1. Preparation of initial molding materials

3.2. Preparation of spent mixture

3.3. Selection of rod mixture

3.4 Automatic moulding line AL

3.5. Selection of equipment for rod fabrication

4. Design and fabrication of casting tooling

4.1 Rod box

5. Metal smelting and filling

5.1. Metal smelting

5.2 Alloy Characteristic

5.3 Charge calculation

6. Calculation of solidification and cooling time of casting

7. Calculation of lifting force acting on the upper half-form and weight of cargo

7.1 Calculation of minimum strength of lower mould

8. Knocking out castings from molds

8.1. Gate System Separation

8.2. Casting cleaning

9. Selection of heat treatment mode

10. Types of marriage and measures to prevent them

11. Basic Casting Control Methods

12. List of literature

1. Design Drawing Analysis

1.1. Purpose and working conditions

The body parts of machines are basic parts on which various attachable parts and assembly units are installed, the accuracy of the relative position of which should be ensured both in static and in the process of operating the machines under load. The housing parts must have the required accuracy, have the necessary parameters of rigidity and vibration resistance, which ensures the constant relative position of the connected parts and assemblies, the correct operation of the mechanisms and the absence of vibrations. Structural design of housing parts, applied material and required accuracy parameters are determined based on service purpose of parts, requirements for operation of mechanisms and conditions of their operation. This also takes into account the technological factors associated with the possibility of obtaining the required configuration of the workpiece, the possibilities of mechanical processing, and the convenience of assembly, which begins with the base body part. The body parts are the most metal-intensive. They account for up to 80% of the total weight of the product. The large size and complex configuration greatly complicate the process of obtaining such parts.

1.3 Technical Requirements for Casting

Technical requirements for part "Gearbox housing":

1) Casting accuracy 8-6-11-8 cm 2 GOST R 53464 - 2009.

2) Unspecified casting radii not more than 1.6 mm

1.4 Choice of Casting Method

The most versatile and common method of casting gearbox bodies is casting into single sand-clay molds. This method has a low cost, but allows to obtain the specified accuracy and configuration of casting under conditions of mass production.

Development of foundry model guidelines (LMUs)

Casting and model instructions (system of graphic image of cast structural and process elements) are applied on the part drawing according to the requirements of the standards:

GOST R 53464 - 2009 values of mechanical machining allowances, process allowances (surges);

GOST R 53465 2009 - moulding slopes;

GOST 321292 - dimensions and slopes of rod signs, values of clearances, retainers, rods.

Preparation of initial molding materials

In order to obtain high-quality moulding and rod mixtures, it is necessary to pre-prepare all initial moulding materials. Therefore, the process of preparing mixtures consists of pre-treatment of fresh sandy-clay materials, special materials, regeneration of the recycled mixture and production of moulding and rod mixtures by mixing in mixers.

The purpose of the raw materials is to restore the properties of the mixture after pouring the metal and maintain them at a given level. The source materials include sands, clays, coal dust.

Moulding materials come from the quarry to the foundry warehouse in a state unsuitable for the preparation of mixtures, therefore, before use, the moulding materials are subjected to preliminary treatment - drying, grinding, sieving.

Sand is dried in drying furnaces at temperature 150-250 ° C. Dried sands are sieved on mechanical sieves of different design to separate large particles and foreign impurities.

Design and fabrication of casting tooling

Model - rod is designed to form inner and outer surfaces of casting. Model and rod tooling includes: models, rod boxes, model boxes. The accuracy of the casting largely depends on the accuracy of its manufacture. According to GOST 321292, 9 accuracy classes for the manufacture of model sets are installed, which are interconnected with the tolerances for the size of castings according to GOST 2664585. The accuracy class of the model set is assigned according to the accuracy class of the casting dimensions. [3]

The model set can be made of wood, metal, plastic, depending on the mass content of production.

We choose metal models, since mass production. Metal models have good accuracy, durability.

The material for making the model is 35L steel.

Types of marriage and measures to prevent them

Failure can be caused by non-compliance with technology, errors in the design of parts, and in the design of the casting process.

The change in the size and contours of the casting under the influence of shrinkage stresses is described. The reasons for this type of marriage may be the irrational design of the casting (for example, difference), which leads to the formation of internal stresses; improper supply of metal, which impairs uniformity of its cooling; improper composition or temperature of the poured metal causing excessive shrinkage; improper cooling mode of casting and insufficient compliance of shape and rods.

Gas shells are the cavities located on the surface or inside the casting. The shape of the shell is spherical or rounded, the surface is smooth shiny. Shells can be single or arranged sockets of different volumes (gas porosity). In most cases, shells are found during machining.

Gas sinks occur when the metal has a high gas content due to poor quality of raw materials and improper melting conditions.

Sandy shells are called closed or open shells. Fully or partially filled with molding material. The reasons for this marriage are as follows: local destruction or clogging of molds during assembly; insufficient strength of moulding and rod mixtures, as well as absence or insufficiency of casting slope in casting, or paints; the use of faulty models, which leads to the showering of the moulding mixture; incorrect design of detachable parts of the model; insufficient attachment of the protruding parts of the mold; weak or uneven packing of molds and rods; mismatch in the dimensions of the sign of the rods and the shape, which leads to crimping of the mold and clogging of it during assembly; improper supply of the sprue system, which leads to erosion of the mold or rod, collapse of the mold when installing the load; non-technological design of casting, i.e. presence of recesses in it, which form fragile thin protrusions and sharp angles in shape.

Shrinkage shells are called open or closed voids in the casting body, having a rough surface with a coarse crystal structure.

Loosening or porosity is the coarse and loose structure of an alloy with the presence of intercrystalline voids of greater or lesser magnitude (shrinkage porosity).

The causes of scrap due to shrinkage shells and loosens may be the incorrect design of the casting, which does not ensure its uniform cooling (there are local accumulations of metal); Insufficient feeding of liquid metal casting during solidification due to improper arrangement of profits, evaporators and runners; incorrect dimensions and installation of refrigerators (metal inserts); increased content of elements increasing shrinkage; excessively high filling temperature.

Cracks are hot and cold to name through and non-through breaks or breaks in cast walls. Fracture surfaces in hot cracks, since they appear at high temperatures, are always oxidized; in cold cracks, the fracture surface is completely clean or covered with a light color of bewilderment. Cracks are detected by tapping, hydraulic penetration, and magnetic flaw detection.

The reasons for the appearance of hot and cold cracks may be the incorrect casting design with a sharp transition from thick to thin sections; sharp internal angles in castings; resistance of molds and rods to normal shrinkage of metal due to excessive packing density; improperly prepared composition of moulding and rod mixtures and their low compliance; incorrect arrangement of ribs of supports or frames in rods, which prevents shrinkage of casting; improper chemical composition, i.e. increased content of elements that increase shrinkage or reduce tensile strength at high temperatures; incorrect filling and heat treatment mode; pouring too hot metal and improper metal supply, which reduces uniform cooling of individual parts of the casting; impacts during runner chopping or during transportation of castings having high internal stresses.

Underfill and sleep. Underfilling is characterized by the fact that when pouring, some parts of the casting remain unfilled. Sleep - through or surface flows with rounded edges of prematurely frozen metal. The reasons for this marriage are the insufficient amount of metal in the ladle; low temperature of alloy during pouring and insufficient fluid flow; leakage of metal from the mold due to loose assembly; insufficient ventilation of the mould and rod, causing increased pressure of gases in the mould; insufficient cross-section of the runner system; irrational casting design due to the presence of too thin walls.

Basic Casting Control Methods

To detect defects on the surface and in the structure of the finished part, quality control procedures will be carried out. In our case, operations such as:

- Visual inspection;

- Measuring;

- X-ray control.

Visual inspection:

Visual inspection means evaluating the surface of the part for defects such as cracks, small inclusions, chips, junctions, etc.

Measurement monitoring:

With this type of control, the part is measured with the help of special devices to detect the correspondence of overall dimensions with the specified in the technology:

- Caliper;

- Micrometer;

- Smooth gauges for internal diameters.

- X-ray monitoring of castings:

The technological process, which includes translucent products, photographic processing of the film, decoding of the obtained radiographs and issuing conclusions. X-ray control allows you to determine the internal geometry of products: (difference, shape deviations, gaps, inclusions). Defects within the allowance for mechanical treatment are allowed on the treated surfaces of castings. Defects are not allowed on untreated surfaces.