Steel is a non-combustible building material that is shock and bending resistant. In practical applications, steel can not only increase the load capacity of buildings, but also meet the needs of architectural design aesthetics. It also avoids the defects that concrete and other building materials cannot bend and stretch. Therefore, steel is favored by the construction industry. Steel is common in single-storey, multi-storey, skyscrapers, factories, warehouses, waiting rooms, and waiting rooms. However, steel as a building material has some inevitable defects in fire protection, and its mechanical properties, such as yield point, tensile strength and elastic modulus, are drastically reduced due to the increase in temperature.
Steel structures usually lose their load carrying capacity at temperatures of 450 to 650 ° C, causing large deformations, resulting in bending of steel columns and steel beams. As a result, they cannot be used due to excessive deformation. Generally unprotected steel structures are fire resistant. The limit is about 15 minutes. The length of this time is also related to the speed at which the component absorbs heat. In order to overcome the fire prevention deficiencies of steel structural materials in practical applications, fireproof treatment must be carried out, the purpose of which is to increase the fire endurance of the steel structure to the limits specified by the design specifications. To prevent the steel structure from rapidly heating up and causing deformation and collapse in the fire, the measures are various. The key is to adopt different methods according to different situations, such as using adiabatic and refractory materials to block the flame and directly burn the steel structure to reduce the speed of heat transfer. Delay the temperature rise of the steel structure and the time when the strength is weakened. But no matter what method is adopted, the principle is the same. The fire protection measures for several different steel structures are described below.
First, the outer layer. It is to add an outer layer on the outer surface of the steel structure, which can be cast in place or sprayed. The cast-in-place solid concrete cladding is usually reinforced with steel mesh or steel to limit shrinkage cracks and to ensure the strength of the outer casing. The spraying method can apply a sand pump to the surface of the steel structure at the construction site to form a protective layer. The sand pump can be lime cement or gypsum mortar, or can be mixed with perlite or asbestos. At the same time, the outer cladding layer can also be made of perlite, asbestos, gypsum or asbestos cement, light concrete, and fixed on the steel structure with adhesive, nails and bolts.
Second, water (water jacket). Filling the hollow steel structure with water is the most effective protection against fire. This method enables the steel structure to maintain a lower temperature in the fire, and the water circulates within the steel structure, absorbing the heat of the material itself. The heated water can be recirculated after cooling, or cold water can be introduced from the pipeline to replace the heated water.
Third, shielding. The steel structure is placed in the wall or ceiling of the refractory material, or the component is hidden in the space between the two walls, and the fireproofing purpose can be achieved by adding a little refractory material or increasing it. This is the most economical way to fire. Fourth, the expansion material. The steel structure fireproof coating protection member adopts the advantages of good fireproof and heat insulation performance, construction is not restricted by the geometric shape of the steel structure, and generally does not need to add auxiliary facilities, and the coating quality is light, and there is a certain decorative effect. It belongs to modern advanced fire protection technology measures.
At present, high-rise steel structures are increasing, especially for some super high-rise buildings, which use steel materials more widely. In the event of a fire accident in a high-rise building, the fire will not be extinguished in a short period of time. This requires us to increase the fire protection of the building materials during the design of the building to enhance its fire resistance and to develop the necessary emergency within the building. Program to reduce casualties and property damage.
CNC Machining is a manufacturing process in which pre-programmed computer software dictates the movement of factory tools and machinery. The process can be used to control a range of complex machinery, from grinders and lathes to mills and routers.
CNC Mills
CNC mills are capable of running on programs comprised of number- and letter-based prompts, which guide pieces across various distances. The programming employed for a mill machine could be based on either G-code or some unique language developed by a manufacturing team. Basic mills consist of a three-axis system (X, Y and Z), though most newer mills can accommodate three additional axes.
CNC Lathes
In lathe machines, pieces are cut in a circular direction with indexable tools. With CNC technology, the cuts employed by lathes are carried out with precision and high velocity. CNC lathes are used to produce complex designs that wouldn`t be possible on manually run versions of the machine. Overall, the control functions of CNC-run mills and lathes are similar. As with the former, lathes can be directed by G-code or unique proprietary code. However, most CNC lathes consist of two axes - X and Z.
CNC Turning
CNC Turning is a manufacturing process in which bars of material are held in a chuck and rotated while a tool is fed to the piece to remove material to create the desired shape. A turret, with tooling attached is programmed to move to the bar of raw material and remove material to create the programmed result. This is also called [subtraction machining" since it involves material removal. If the center has both tuning and milling capabilities, the rotation can be stopped to allow for milling out of other shapes.
The starting material, though usual round, can be other shapes such as squares or hexagons.
Depending on the bar feeder, the bar length can vary. This affects how much handling is required for volume jobs.
CNC lathes or turning centers have tooling mounted on a turret which is computer-controlled. The more tools that that the turret can hold, the more options are available for complexities on the part.
CNC`s with [live" tooling options, can stop the bar rotation and add additional features such as drilled holes, slots and milled surfaces.
Some CNC turning centers have one spindle, allowing work to be done all from one side, while other turning centers, have two spindles, a main and sub-spindle. A part can be partially machined on the main spindle, moved to the sub-spindle and have additional work done to the other side this configuration.
There are many different kinds of CNC turning centers with various types of tooling options, spindle options, outer diameter limitations as well as power and speed capabilities that affect the types of parts that can be economically made on it.
CNC Grinder
CNC grinding is a machining technology which utilizes a high-tech ultramodern type of grinding machine known as a CNC grinding machine. The CNC technology, also known as Computerised Numerical Control, is an automation process that utilizes computer programs to control grinding machines.
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