NAFCO | Forging of China Brass Ball Valves and Brass Fittings

NAFCO | Forging of China Brass Ball Valves and Brass Fittings
Time:2017-10-18 From: NAFCO-China Brass Ball Valves and Brass Fittings Manufacturer
Here we introduce the relevant knowledge of brass valve and brass fittings forging.
1, Classifications of forging
I). According to the deformation temperature classification:
The recrystallization temperature of the brass is about 727 ℃, but 800 ℃ is used as the dividing line.
The hot forging is higher than 800 ℃, and it is called hot forging or semi-hot forging between 300 and 800 ℃.
Forging for China Brass Ball Valves
II). According to the blank classification:
Forging can be divided into free forging, upsetting, extrusion, die forging, closed forging, closed upsetting.
1). Free forging. The use of impact or pressure to make the metal in the upper and lower iron (anvil) between the deformation to get the required forgings, mainly forging and mechanical forging two.
2). Die forging is divided into open forging and closed forging. Metal blanks in a certain shape of the forging furnace pressure deformation and get forgings, can be divided into cold forging, roll forging, radial forging and extrusion and so on.
3). Closed die forging and closed upsetting because there is no flash, the material utilization rate is high. With a process or a few processes may be completed complex forging finishing. In the absence of a flash, the area of force for the forging is reduced and the required load is reduced. However, it should be noted that the blank can not be completely restricted, for which to strictly control the volume of the blank, control the relative position of the forging die and forging measurements, efforts to reduce the forging die wear.

III). according to the forging mode of movement classification:
Forging can be divided into swing roll, swing forging, roll forging, cross wedge rolling, rolling ring and inclined rolling and so on. Swing roll, swing forging and rolling ring can also be used forging for processing. In order to improve the utilization of the material, roll forging and cross rolling can be used as an elongated material before the process of processing. And free forging the same rotary forging is also a partial shape, and its advantage is compared with the size of forging, forging force can also be achieved under small circumstances. Including the free forging within the forging method, the processing of materials from the mold surface near the free surface to expand, so it is difficult to ensure accuracy, so the direction of the forging die and forging process with computer control, you can use lower Of the forging force to obtain complex shapes, high precision products, such as the production of many varieties, large size turbine blades and other forgings. Forging equipment mold movement and degree of freedom is inconsistent, according to the characteristics of the bottom dead point deformation; forging equipment can be divided into the following four forms:
1). Restricted forging force form: hydraulic direct drive slider hydraulic press.
2). Quasi-stroke limit: hydraulic drive crank connecting rod mechanism.
3). Stroke Restrictions: Crank, connecting rod and wedge mechanism Drive the slider of the mechanical press.
4). Energy limits: spiral and friction presses using screw mechanisms.

China brass ball valves for hydraulic presses In order to obtain high accuracy, care should be taken to prevent overload, control speed and mold position at the bottom dead center. Because these will have the impact of forgings tolerance, shape accuracy and forging die life. In addition, in order to maintain accuracy, should also pay attention to adjust the slider rail clearance, to ensure stiffness, adjust the bottom dead center and the use of auxiliary transmission and other measures.

As well as the vertical and horizontal movement of the slider (for forging parts of the elongated parts, lubrication and high-speed production of forging parts) way, the use of compensation device can be successfully forged the first large-scale disk products to increase the direction of movement The above factors are different, the required forging force, process, material utilization, yield, dimensional tolerances and lubrication cooling methods are different, these factors are also factors that affect the level of automation.

2, the importance of forging
Forging is a critical process for China brass valves and China brass fittings production, which provides basic pressure resistance and leakage tightness. Forging production is one of the main processing methods for the provision of mechanical parts in the machinery manufacturing industry. Through forging, not only can get the shape of mechanical parts, but also to improve the internal metal structure, improve the mechanical properties of metal and physical properties. Generally on the force, demanding high mechanical parts, most of the use of forging production methods. Such as turbo-generator shaft, rotor, impeller, blade, retaining ring, large hydraulic press column, high pressure cylinder, rolling mill roll, internal combustion engine crankshaft, connecting rod, gear, bearing, and national defense industry and other important parts, produce.
Therefore, forging production is widely used in metallurgical, mining, automobile, tractor, harvesting machinery, petroleum, chemical, aviation, aerospace, weapons and other industrial sectors, is in daily life, forging production also has an important position. In a sense, the annual output of forgings, the proportion of forging in the total yield of forgings, and the size and ownership of forging equipment, to a certain extent, reflects a country's industrial level.

3, Forging Materials
Forging materials are mainly composed of various components of carbon steel and alloy steel, followed by aluminum, magnesium, copper, titanium and its alloys. The original state of the material is bar, ingot, metal powder and liquid metal. The ratio of the cross-sectional area of the metal before deformation to the cross-sectional area after deformation is called the forging ratio. Correct choice of forging ratio, reasonable heating temperature and holding time, reasonable initial forging temperature and final forging temperature, reasonable deformation and deformation speed to improve product quality and reduce costs have a great relationship. Forging is also widely used for China brass ball valves, brass radiator valves, brass gate valves, brass angle valves.

General small and medium-sized forgings are round or square bar as a blank. Bar material grain and mechanical properties of uniform, good, accurate shape and size, good surface quality, easy to organize mass production. As long as the reasonable control of heating temperature and deformation conditions, do not need large forging deformation can be forging performance excellent forging. Ingredients are used only for large forgings. The ingot is as-cast, with a larger columnar and loose center. Therefore, it is necessary to break the columnar grains into fine grains by large plastic deformation, which will be loose and compacted in order to obtain excellent metal structure and mechanical properties.

The pressed and sintered powder metallurgy preforms can be made into powder forging by hot forging. Forging powder is close to the density of the general forging, has good mechanical properties, and high precision, can reduce the follow-up cutting. Powder forging internal tissue uniform, no segregation, can be used to manufacture small gears and other parts. But the price of the powder is much higher than the price of the general bar, the application in the production is subject to certain restrictions. The hydrothermally applied to the liquid metal cast in the mold chamber to solidify, crystallize, move, plastically deform and shape under pressure to obtain the desired shape and properties of the die forging. Liquid metal die forging is a die forming and die forging between the forming method, especially for the general forging difficult to shape the complex thin-walled pieces.

Forging materials In addition to the usual materials, such as various components of carbon steel and alloy steel, followed by aluminum, magnesium, copper, titanium and other alloys, iron-based superalloy, nickel-based superalloy, cobalt-based superalloy Of the deformation of the alloy is also used forging or rolling to complete, but these alloys because of its relatively narrow plastic area, so the difficulty of forging relatively large, different materials, heating temperature, forging temperature and final forging temperature have strict requirements.

4, Forging Processes
Different forging methods have different processes, in which the process of hot forging the longest, the general order: forging blanking; forging billet heating; roll forging blanks; forging forming; trimming; punching; The inspection, the general forgings to go through the appearance and hardness of the inspection, the important forging also to ensure that the forging stress, to improve the metal cutting performance; cleaning, mainly to remove the surface oxide; To undergo chemical composition analysis, mechanical properties, residual stress and other tests and nondestructive testing.

5, Forging Features and Advantages
Brass material bars will be cut to small pieces according to product dimensions before forging. Generally speaking, the brass valves are bigger than brass fittings in China. Compared with the casting, the metal after forging processing can improve its organizational structure and mechanical properties. Casting tissue after forging process thermal deformation due to metal deformation and recrystallization, the original coarse dendrites and columnar grains into fine grain size, uniform size of the equaled recrystallization structure, so that the original ingot segregation, Loose, porosity, slag and other compaction and welding, the organization becomes more closely, to improve the plasticity and mechanical properties of the metal. The mechanical properties of the castings are lower than those of the same material. In addition, forging processing to ensure the continuity of metal fiber organization, so that forging the fibrous tissue and forging shape consistent, complete metal line, can ensure that the parts have good mechanical properties and long service life using precision die forging, cold extrusion.
Temperature extrusion and other processes for the production of forgings, are castings can not match the forging is the metal is applied pressure, through the plastic deformation of the shape required to shape or the appropriate compression of the object. This force is typically achieved by using a hammer or pressure. The casting process builds fine particle structures and improves the physical properties of the metal. In the practical use of components, a correct design can make the flow of particles in the direction of the main pressure. Castings are made of various casting methods of metal forming objects, that is, smelting a good liquid metal, with casting, injection, inhalation or other casting method into the prepared mold, after cooling down the sand, clean up and after Processing, etc., obtained with a certain shape, size and performance of the object.

6, Forging Process :

1). Forging process involves cutting the material to the desired size, heating, forging, heat treatment, cleaning and inspection. In small artificial forging, all of these operations are carried out by a few forges and start in a small place. They are exposed to the same harmful environment and occupational hazards; in large forging workshops, the hazards vary from job to work. Working conditions although the working conditions vary depending on the forging form, they have some common characteristics: moderate strength labor, dry heat, microclimate, noise and vibration, air pollution by smoke.

2). Workers exposed to high temperature air and heat radiation, resulting in the accumulation of heat in the body, heat plus metabolic heat, can cause cooling disorders and pathological changes. The sweat amount of 8 hours of labor will vary from 1.5 to 5 liters, or even higher, depending on the small gas environment, physical exertion, and the degree of thermal suitability. In the smaller forging workshop or from the heat source, the Beja two heat stress index is usually 55 to 95; but in the large forging workshop, near the furnace or hammer machine operating point may be as high as 150 ~ 190. Easily lead to lack of salt and heat spasm. In the cold season, exposure to changes in the microclimate environment may contribute to a certain degree of adaptability, but rapid and frequent changes may pose a health hazard.
Air pollution: The air in the place may contain soot, carbon monoxide, carbon dioxide, sulfur dioxide, or also contain acrolein, depending on the type of fuel furnace and the impurities contained therein, as well as the combustion efficiency, airflow and ventilation conditions. Noise and vibration: type forging hammer will inevitably produce low-frequency noise and vibration, but there may be a certain high-frequency components, the sound pressure level between 95 to 115 dB. Staff exposure to forged vibrations may cause temperament and functional disorders, which can reduce the ability to work and affect safety.

7, Forging Production Risks and Reasons:

First, in forging production, prone to traumatic accidents, according to their reasons can be divided into three categories:
Mechanical injury - a tool or work piece directly caused by scratches, bumps; burns;

Second, from the perspective of security technology labor protection, forging workshop is characterized by:
1). Forging production is carried out in the state of hot metal (such as low carbon steel forging temperature range between 1250 ~ 750 ℃), due to a large number of manual labor, a little care may occur burns.

2) The heating furnace and the hot steel ingots, roughing and forgings in the forging workshop are constantly diverging from a large amount of radiant heat (the forgings still have a very high temperature at the end of the forging), and workers are often exposed to heat radiation.

3). The furnace in the forging workshop is discharged into the air of the workshop in the air of the workshop, which not only affects the hygiene but also reduces the visibility in the workshop (the situation is more serious for burning the solid fuel) may also cause accidents.

4). Forging the use of equipment such as air hammer, steam hammer, friction presses, etc., are issued when the impact of force. The equipment is susceptible to sudden damage (such as a sudden break of the hammer piston rod) when it is subjected to such an impact load, causing serious injury.

Presses (such as hydraulic press, crank hot forging presses, flat forging machine, precision press) shear bed, etc., at work, although the impact of small, but the equipment suddenly damaged, etc. also occur, the operator Often caught off guard, may also lead to industrial accidents.

5). Forging equipment in the work of the force is very large, such as crank press, tensile forging presses and hydraulic press such as forging equipment, their working conditions are relatively stable, but its work components are the power of Very large, such as China has made and used 12000t forging hydraulic press. Is the common 100 ~ 150t of the press, the power is enough to issue a large. If the mold is installed or operated incorrectly, most of the force is not acting on the work piece, but on the part of the mold, tool, or device itself. In this way, improper installation errors or improper operation of the tool may cause damage to the parts and other serious equipment or personal accidents.
6). Forging tools and auxiliary tools, especially forged and free forging tools, clamps and many other names, these tools are placed together in the workplace. In the work, the tool is very frequent replacement, storage is often messy, which will inevitably increase the difficulty of checking these tools, when forging a tool and often cannot quickly find, sometimes "improvise" use Similar tools, which often cause accidents.
7). As the noise and vibration of the forging workshop equipment during operation, the workplace is noisy, affecting people's hearing and nervous system, distracting attention, thus increasing the possibility of accidents.

Analysis on the Causes of Work - related Accident in Forging Workshop:
1). Areas requiring protection, lack of protective equipment and safety equipment.
2) The protective device on the device is imperfect or unused.
3) The production equipment itself is defective or defective.
4) Equipment or tool damage and working conditions are inappropriate.
5). Forging die and anvil are faulty.
6) Workplace organization and management of the chaos.
7). The method of operation and the auxiliary work of repair are inappropriate.
8). Personal protective equipment such as protective glasses are faulty, work clothes and work shoes do not meet the working conditions.
9). When a few people work together, they cooperate with each other.
10). Lack of technical education and safety knowledge, resulting in the use of incorrect steps and methods.

8, Forging Industry Analysis
China forging industry is in the introduction, digestion, absorption of foreign technology developed on the basis of years of technological development and transformation of the industry leading enterprises in the technical level, including process design, forging technology, heat treatment technology, machining technology, products Testing and other aspects have been greatly improved.

1) process design
Advanced manufacturers commonly used thermal processing computer simulation technology, computer-aided process design and virtual technology; improve the level of process design and product manufacturing capacity. Introduced and applied DATAFOR, GEMARC / AUTOFORGE, DEFORM, LARSTRAN / SHAPE and THERMOCAL simulation program, to achieve computer design and thermal processing process control for brass ball valves and brass fittings.

2) forging technology
40MN and above hydraulic press most equipped with 100-400t.m main forging operation machine and 20-40t.m auxiliary operation machine, a considerable number of operating machine using computer control, to achieve a forging process of integrated control, so that forging accuracy can be Control at ± 3mm, forging the on-line measurement using laser size measuring device.

3) Heat treatment technology
The focus is to improve product quality and improve heat treatment

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