![]() | This article has multiple issues. Please help improve it or discuss these issues on the talk page . (Learn how and when to remove these template messages)
|
Shot peening can be used to recondition distorted steel conveyor belts. The shot peening process is quick and cost-effective compared with other methods and does not interrupt daily production.[ citation needed ] A deformed steel belt has the following disadvantages:[ citation needed ]
Shot peening is a maintenance process for flattening a deformed steel belt in which the surface of the belt is impacted by small spherical stainless steel or carbon steel balls called peening shot. Each shot hitting the belt functions as a small peening hammer, forming a small indentation or dimple on the steel belt surface. In order for the indentation to be formed, the steel belt surface layer must yield in tension.[ citation needed ][ clarification needed ] The compressed grains[ clarification needed ] help to restore the surface to its original shape by producing a hemisphere[ clarification needed ] of cold-worked metal highly stressed in compression. Overlapping indentations create a continuous layer of residual compressive stress. It is well known that cracks will not lead up[ clarification needed ] nor propagate in a compressive stressed zone. Because nearly all fatigue and stress corrosion failures originate at the surface of a part, compressive stresses generate by shot peening provide very important increases in lifetime.[ citation needed ] Note that:
The main use of the unit is to flatten out deformed press belts whilst simultaneously stress-relieving the belt material. The small size and low weight make the unit flexible and easy to bring into and operate in field situations. All of the equipment needed (excluding the carriage frame and the air compressor) can be packed into a box with dimensions of about: 350mm L × 350mm W × 320 mm. Total weight including blaster, valve, air hose and miscellaneous components is around 25 kg and the blasting machine itself weighs only 9 kg. One pair of universal channel (38 mm * 76 mm) must be provided on site – the length usually being 500 mm longer than the belt width. The channels are welded together so that the blaster can easily run through the frame across the face of the belt. The total installation time, including the manufacture of the carriage frame, is limited to just a few hours after which the peening process can begin.
On the inlet air hose an electric shut-off valve is mounted to protect the belt from over-blasting should the belt suddenly stop during the blasting operation. To be effective, the valve solenoid must be connected / interlocked to the press machine's power supply (240 V). For best blasting results, an air supply of 4200 litres per minute is required at a pressure of 6 bar. A flexible air hose is supplied with the unit, which is to be connected between the blasting unit and the local air supply. All local supply pipes should have a minimum bore diameter of 1 inch. The recommended shot blasting medium is tungsten shot (beads) with diameter ranging from 0.2 to 0.4 mm and a hardness exceeding 40 HRC. The machine operates by drawing a quantity of tungsten shot from the bottom of the scroll case into the high-velocity nozzles. The shot is blasted onto the surface of the belt, and most of the shot bounces back into the scroll case. The air is vented through the filter socks, and any shot carried with the air is filtered out and drops back into the scroll case.
Historically (per 1980s), the common method previously used to solve the problem of deformed belts was to turn the belt over, i.e. what was previously the back of the belt is then used to form the new product side. The belt became flatter when it was turned because of an equalization of the stresses on the two sides.
However, the belt usually continues to change its shape so that it eventually acquires the same shape as before being turned but in the opposite direction. Because of this, turning the belt again after a period of approximately one year was often necessary. This method is very time-consuming and thus very costly since it involves cutting the belt, dismantling it from the press, turning the belt and re-installing it in the press, followed by the belt joining operations (welding and grinding of the joint) and running-in procedures. All these operations also require equipment for handling the belt as well as special welding jigs and skilled personnel for the joint-welding. Added to this is the loss of production during the operation – a stoppage in production of one week is not uncommon. The steel belt shot peening process was developed as a superior solution to the Belt cross curvature problem.
A scuba set, originally just scuba, is any breathing apparatus that is entirely carried by an underwater diver and provides the diver with breathing gas at the ambient pressure. Scuba is an anacronym for self-contained underwater breathing apparatus. Although strictly speaking the scuba set is only the diving equipment that is required for providing breathing gas to the diver, general usage includes the harness or rigging by which it is carried and those accessories which are integral parts of the harness and breathing apparatus assembly, such as a jacket or wing style buoyancy compensator and instruments mounted in a combined housing with the pressure gauge. In the looser sense, scuba set has been used to refer to all the diving equipment used by the scuba diver, though this would more commonly and accurately be termed scuba equipment or scuba gear. Scuba is overwhelmingly the most common underwater breathing system used by recreational divers and is also used in professional diving when it provides advantages, usually of mobility and range, over surface-supplied diving systems and is allowed by the relevant legislation and code of practice.
An air compressor is a machine that takes ambient air from the surroundings and discharges it at a higher pressure. It is an application of a gas compressor and a pneumatic device that converts mechanical power into potential energy stored in compressed air, which has many uses. A common application is to compress air into a storage tank, for immediate or later use. When the delivery pressure reaches its set upper limit, the compressor is shut off, or the excess air is released through an overpressure valve. The compressed air is stored in the tank until it is needed. The pressure energy provided by the compressed air can be used for a variety of applications such as pneumatic tools as it is released. When tank pressure reaches its lower limit, the air compressor turns on again and re-pressurizes the tank. A compressor is different from a pump because it works on a gas, while pumps work on a liquid.
A self-contained breathing apparatus (SCBA) is a respirator worn to provide an autonomous supply of breathable gas in an atmosphere that is immediately dangerous to life or health from a gas cylinder. They are typically used in firefighting and industry. The term self-contained means that the SCBA is not dependent on a remote supply of breathing gas. They are sometimes called industrial breathing sets. Some types are also referred to as a compressed air breathing apparatus (CABA) or simply breathing apparatus (BA). Unofficial names include air pack, air tank, oxygen cylinder or simply pack, terms used mostly in firefighting. If designed for use under water, it is also known as a scuba set.
A hydrostatic test is a way in which pressure vessels such as pipelines, plumbing, gas cylinders, boilers and fuel tanks can be tested for strength and leaks. The test involves filling the vessel or pipe system with a liquid, usually water, which may be dyed to aid in visual leak detection, and pressurization of the vessel to the specified test pressure. Pressure tightness can be tested by shutting off the supply valve and observing whether there is a pressure loss. The location of a leak can be visually identified more easily if the water contains a colorant. Strength is usually tested by measuring permanent deformation of the container.
A pressure vessel is a container designed to hold gases or liquids at a pressure substantially different from the ambient pressure.
Hydraulic machines use liquid fluid power to perform work. Heavy construction vehicles are a common example. In this type of machine, hydraulic fluid is pumped to various hydraulic motors and hydraulic cylinders throughout the machine and becomes pressurized according to the resistance present. The fluid is controlled directly or automatically by control valves and distributed through hoses, tubes, or pipes.
Shot peening is a cold working process used to produce a compressive residual stress layer and modify the mechanical properties of metals and composites. It entails striking a surface with shot with force sufficient to create plastic deformation.
In materials science and solid mechanics, residual stresses are stresses that remain in a solid material after the original cause of the stresses has been removed. Residual stress may be desirable or undesirable. For example, laser peening imparts deep beneficial compressive residual stresses into metal components such as turbine engine fan blades, and it is used in toughened glass to allow for large, thin, crack- and scratch-resistant glass displays on smartphones. However, unintended residual stress in a designed structure may cause it to fail prematurely.
A pipe is a tubular section or hollow cylinder, usually but not necessarily of circular cross-section, used mainly to convey substances which can flow — liquids and gases (fluids), slurries, powders and masses of small solids. It can also be used for structural applications; hollow pipe is far stiffer per unit weight than solid members.
An Almen strip is a thin strip of SAE 1070 steel used to quantify the intensity of a shot peening process.
A fitting or adapter is used in pipe systems to connect sections of pipe or tube, adapt to different sizes or shapes, and for other purposes such as regulating fluid flow. These fittings are used in plumbing to manipulate the conveyance of fluids such as water for potatory, irrigational, sanitary, and refrigerative purposes, gas, petroleum, liquid waste, or any other liquid or gaseous substances required in domestic or commercial environments, within a system of pipes or tubes, connected by various methods, as dictated by the material of which these are made, the material being conveyed, and the particular environmental context in which they will be used, such as soldering, mortaring, caulking, Plastic welding, welding, friction fittings, threaded fittings, and compression fittings.
Laser peening (LP), or laser shock peening (LSP), is a surface engineering process used to impart beneficial residual stresses in materials. The deep, high-magnitude compressive residual stresses induced by laser peening increase the resistance of materials to surface-related failures, such as fatigue, fretting fatigue, and stress corrosion cracking. Laser shock peening can also be used to strengthen thin sections, harden surfaces, shape or straighten parts, break up hard materials, compact powdered metals and for other applications where high-pressure, short duration shock waves offer desirable processing results.
A pressure regulator is a valve that controls the pressure of a fluid to a desired value, using negative feedback from the controlled pressure. Regulators are used for gases and liquids, and can be an integral device with a pressure setting, a restrictor and a sensor all in the one body, or consist of a separate pressure sensor, controller and flow valve.
Oxy-fuel welding and oxy-fuel cutting are processes that use fuel gases and oxygen to weld or cut metals. French engineers Edmond Fouché and Charles Picard became the first to develop oxygen-acetylene welding in 1903. Pure oxygen, instead of air, is used to increase the flame temperature to allow localized melting of the workpiece material in a room environment.
Sandblasting, sometimes known as abrasive blasting, is the operation of forcibly propelling a stream of abrasive material against a surface under high pressure to smooth a rough surface, roughen a smooth surface, shape a surface or remove surface contaminants. A pressurised fluid, typically compressed air, or a centrifugal wheel is used to propel the blasting material. The first abrasive blasting process was patented by Benjamin Chew Tilghman on 18 October 1870.
Low plasticity burnishing (LPB) is a method of metal improvement that provides deep, stable surface compressive residual stresses with little cold work for improved damage tolerance and metal fatigue life extension. Improved fretting fatigue and stress corrosion performance has been documented, even at elevated temperatures where the compression from other metal improvement processes relax. The resulting deep layer of compressive residual stress has also been shown to improve high cycle fatigue (HCF) and low cycle fatigue (LCF) performance.
The high-frequency impact treatment or HiFIT – Method is the treatment of welded steel constructions at the weld transition to increase the fatigue strength.
A steel belt is a type of conveyor belt used in many industries such as food, chemical, wood processing, and transportation.
Peen may refer to:
In metallurgy, peening is the process of working a metal's surface to improve its material properties, usually by mechanical means, such as hammer blows, by blasting with shot, focusing light, or in recent years, with water column impacts and cavitation jets. With the notable exception of laser peening, peening is normally a cold work process tending to expand the surface of the cold metal, thus inducing compressive stresses or relieving tensile stresses already present. It can also encourage strain hardening of the surface metal.