The fourth chapter black area process 4.1 black area design scheme and production process


First, a brief introduction to the division of lost foam: lost foam production includes mold making, brushing group mold drying, sand treatment, commonly known"White Zone", "Yellow Zone" and "Black Zone". First of all, let's talk about the workflow of the black area of the lost model.

4.1.1 Working flow of lost foam black area

The working process of the black area of the lost matrix is as follows:

Take the automatic rigid closed-loop separation production line as an example:

Figure 1

FigureAs shown in 1:

The functional areas of the black area of the lost vanisher include: modeling work department, negative pressure system, (smelting) pouring work department, sand box casting cooling, sand box operation work department, sand falling work department, sand treatment system, dust removal system, water circuit system, gas circuit system and hydraulic system;

Among them, the modeling department is introduced:

After the castings in the sand box reach the cooling time, the castings in the sand box and the casting sand are separated from the sand box by the turning equipment or the sand dropping device. At this time, the empty sand box just turned over has a higher temperature (in order to avoid thermal deformation caused by contact between the model cluster and the sand box, it is reasonable to cool the sand box for a certain time when the model cluster is placed). First, add bottom sand, vibrate the modeling equipment and then put the model cluster,According to the technical requirements of the on-site casting, the layers are divided into Gaza and thenLaminated pouring riser.

Figure2  

FigureThe process shown in 2 is as follows: adding bottom sand → putting model cluster → adding sand to vibrate → coating film (adding surface sand behind peritoneum) → putting pouring riser.

Negative pressure system: At present, the negative pressure system can be connected to the sand box by manual docking and automatic docking devices.Pouring operation can only be carried out when the vacuum degree reaches the allowable pouring pressure of the casting.. However, the pouring can be carried out by crane lifting and pouring and equipped with pouring machine.

Sand Falling Industry Department: casting sand can be separated from castings by means of automatic box turning machine, crane lifting and turning box or bottom tribal sand, and the casting sand enters the sand treatment system.

Sand treatment system: Sand treatment equipment is one of the most important processes of lost foam casting. The reuse of old sand is a key link in the stability of casting sand quality and an important guarantee for improving productivity.

1) Screen out the impurities in the sand, iron pieces, paint blocks and other large particles and.Dust below 50 mesh;

2) Magnetic separation to remove iron beans in the sand;

3) Cooling the return sandBelow 50 ℃ (the model will be deformed at 70 ℃)

4) Storage of molding sand;

5) Transportation of old sand;

  At present, the sand processing system of the lost foam production line can be fully automated without the need for workers to operate.

Dust removal system: mainly sand treatment link and pouring link of dust removal, to meet the requirements of the dust removal system is the lost mode workshop guarantee."No dust in the air, no sand on the ground" green casting process requirements.

Please look at the association of each functional area below, as shown in the figure3 as shown

   

Figure 3

4.1.2 Sand for lost foam casting

Let's talk about the following contents of lost foam casting sand and the performance requirements of dry sand: dry sand containing a large amount of dust will reduce air permeability and hinder the discharge of gas during pouring; Coarse sand particles are prone to sticky sand and rough casting surface. Round or semi-polygonal dry sand can improve air permeability. Round sand has the best fluidity and compactness.

At present, the commonly used sand for lost foam casting is silica sand, casting grade jewel sand.

Silica sand: akaQuartzSand. Is quartz as the main mineral composition, according to the different mining and processing methods are divided into artificial silica sand and water washing sand, scrubbing sand, selected (flotation) sand and other natural silica sand. Silica sand is a kind of hard, wear-resistant, chemically stable silicate mineral, its main mineral composition isSiO2, silica sand color is milky white or colorless translucent, hardness 7, brittle without cleavage, shell fracture, grease luster, relative density of 2.65, its chemical, thermal and mechanical properties have obvious anisotropy, insoluble in acid, slightly soluble in KOH solution, melting point of 1750 ℃. The color is milky white, yellowish, brown and gray, and the silica sand has high fire resistance.

Silica sand for the production of cast steel, general requirementsSiO2 content in more than 95%.

Natural silica sand: according to the local custom of production, it is divided"Sea sand" and "Sedimentary sand;

"Sea sand" is taken from the sand near the seaside tidal zone, with more impurities, SiO2 content between 92%-97%, but the sand particles are basically round. Sea sand mining is convenient.

"Sedimentary sand" is mostly deposited near the coast. The covering soil layer on the surface of the ore occurrence is about 1 m thick, and the sand layer is generally between 4 and 8 m. The SiO2 content of the raw sand supplied is mostly about 97%, and the sand grains are mainly polygonal.

Jewel sand: is a high-grade substitute for quartz sand, for artificial sand, its manufacturing method is: high-quality bauxite as raw material,Calcination, electric melting, granulation, sieve and other processes, after cooling of the jewel sand for spherical or close to spherical particles, smooth surface.

 

Microscopic Portrait of Jewelry Sand[1]The treasure sand picture under the microscope

The difference between jewel sand and quartz sand is:

The advantages of quartz sand are widely distributed and low cost; but its disadvantages are also quite obvious: first, the expansion coefficient is large, and the casting precision is low; second, the surface of the casting is seriously sticky sand, and it is difficult to clear sand. The reason is that quartz will have a variety of homogeneous and heterogeneous crystals at different temperatures, with large volume changes. Refractory(the refractoriness of quartz sand is between 1400 -1700 ℃), the local parts of the casting (holes, grooves, and the parts where the hot spots are concentrated) stick to the sand seriously, and it is very difficult to clean up. These shortcomings are particularly important in the production of large steel castings.Seriously.

Jewelry sand can overcome these shortcomings, thereby greatly improving the quality of castings. Jewelry sand has good fluidity and good compaction effect on the modeling department.

4.1.3 Layout and classification of lost foam black area production line

Let's talk about the last content, the layout and classification of the lost foam black area production line.

First of all, let's talk about the classification of the black area production line:

At present, there are many ways to arrange the lost foam production line, and the main classification can be classified according to the degree of automation, rigidity and flexibility, open-loop or closed-loop type.


 

Among them, the automatic operation line refers to: the production line sand box operation is.PLC program control, mechanical or hydraulic device drive, no manual operation.

Rigid line: in the production line, the sand boxes are continuously densely distributed without gaps. The length of the production line has a strict corresponding relationship with the number of sand boxes and the length of the sand boxes. The sand boxes of the whole line move uniformly during operation. (Rigid lines are mostly used for uniform sand box length)

Flexible line: in the production line, there is no strict correspondence between the length of the production line and the number of sand boxes. The sand boxes can be arranged arbitrarily in the production line and can be moved separately. The sand boxes do not need to be of uniform length.

Closed loop line: the sand box in the production line can realize circular operation without borrowing external equipment.

Open loop line: the sand box in the production line needs to borrow external equipment.(such as the crane, etc.) to achieve circular operation.

Separation line: When we have been making plans for many years, we have reduced equipment investment, improved efficiency, and designed a layout of a separate production line, which is a running line with parallel branches at the same step in the production line. (Three examples of lower production line)

Here are examples of production lines:

   Production Line One

12

ROFY-20B

negative pressure system

1

8

ROSX-II

Sand box

 

4

ROSS-I

Screening conveyor

1

11

ROF6-1

six-station distributor

1

7

ROLW-I

Material level detection device

1

3

ROLS-A

Manual sand drop device

1

10

ROCC-1

Bag dust collector

1

6

ROSD-I

Sand storage hopper

1

2

ROLS-I

Sand drop

1

9

ROZS-1

Vibrostation

1

5

ORLL-I

vertical cooling machine

1

1

ROFX-I

Turn over box support

1

Serial Number

Figure No.

Name

Quantity

Serial Number

Figure No.

Name

Quantity

No.

Figure No.

Name

Quantity

 

Production line one is a simple crane lifting, flexible open-loop production line, annual output.2000T/year/shift, the operation of the sand box is mainly completed by the crown block, and the main functions of the sand processing equipment are screening, lifting, cooling and dust removal;

Advantages: The cooling equipment includes cooling and lifting, saving the hoist, occupying a small area and less investment.

Production line two:

Production line 2 is also a flexible open-loop production line, the difference is that the sand treatment system is increased, with a sand box track, manual can directly move the sand box through the track.

Production line three:

Such an arrangement is an automatic rigid closed loop separation line.The molding line is separated from the casting area and can work independently in different areas. The production line is a closed rigid circulation line with automatic box turning and sand dropping and automatic docking negative pressure interface;

The circular work department is designedThere are three parts: 1 independent molding line, 2 casting lines and 1 return cooling line. These three parts work independently and are interrelated. They run orderly and the running beat of the circulating work department can be adjusted.

The mobile sand box and the running trolley are designed on the track. The displacement of the sand box is carried out in a straight line by hydraulic pushing. A mechanical automatic alignment mechanism is set on each modeling line to ensure that the sand box makes parallel straight line movement during the track operation without deviation.

A mechanical automatic alignment mechanism is set up on each single line to ensure that the automatic negative pressure interface and the sand box exhaust port are accurately and automatically docked without dislocation.

How to choose the production line: lost foam casting industry in the continuous development of lost foam casting technology is also maturing. More and more foundry enterprises need to use lost foam casting process to complete production according to their own product characteristics.

   Choose the principle of production line:

1) Determine the production program (production mode, work system, output, etc.)

2) Process analysis

3) Workshop Graphic Design

4) Logistics design (smelting work department is close to pouring work department, model insulation room to be used in yellow area is close to modeling work department, cleaning work department is close to sand falling work department.

The selection of the appropriate production line must comply with relevant national policies (dust removal, noise and other relevant national regulations), practical, safe and applicable, technologically advanced, economical and practical.

    In short, scientific and reasonable production line planning of lost vanishing mold is very important to enterprises. Scientific and reasonable lost vanishing mold production line allows enterprises to reduce investment and improve workshop utilization, scientific and reasonable production line can make production smoother and safer. In short, scientific and reasonable lost-vanishing mold production line allows enterprises to obtain lower consumption and more efficient production capacity.

 

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