A rotary union is a union that allows for rotation of the united parts. It is thus a device that provides a seal between a stationary supply passage (such as pipe or tubing) and a rotating part (such as a drum, cylinder, or spindle) to permit the flow of a fluid into and/or out of the rotating part. Fluids typically used with rotary joints and rotating unions include various heat transfer media and fluid power media such as steam, water, thermal oil, hydraulic fluid, and coolants. [2] A rotary union is sometimes referred to as a rotating union, rotary valve, swivel union,rotorseal, [3] rotary couplings, rotary joint, rotating joints, hydraulic coupling, pneumatic rotary union, through bore rotary union, air rotary union, electrical rotary union, or vacuum rotary union [4]
A rotary union will lock onto an input valve while rotating to meet an outlet. During this time the liquid and/or gas will flow into the rotary union from its source and will be held within the device during its movement. This liquid and/or gas will leave the union when the valve openings meet during rotation, and more liquid and/or gas will flow into the union again for the next rotation. Often functioning under high pressure and constant movement, a rotary union is designed to rotate around an axis. A rotary union's design can be altered to change this or to increase the psi or rpm it needs to withstand as well as the number of valves required.
While rotary unions come in many shapes, sizes, and configurations, they always have the same four basic components: a housing unit, a shaft, a bearing (mechanical) (or bearings), and a seal. Rotary unions typically are constructed from stainless steel to resist rust and corrosion, but many other metals can be involved, like aluminum.
The housing is the component that holds all of the other elements of the rotary union together. The housing has an inlet port, which is a threaded port to which the hose supplying the medium will be attached. The rotary union may also have an outlet port, if the same joint is being used both to supply fluid to a roll and to remove fluid from the roll. In smaller rotary unions the housing is stationary. In larger rotary unions the housing is usually bolted to the drum or roll using a flange. In these cases the housing rotates at the same speed as the drum [5]
The shaft is the component that carries the medium through the rotary union into the drum or roll. In many cases the shaft will turn with the drum or roll. In some cases, like in larger flanged rotary unions, the shaft may be stationary while the housing rotates. The bearings and seal are typically assembled around the shaft.
The second most important part of the rotary union is the bearing. A rotary union may have only one bearing, but multiple bearing are much more common. Roller bearings; such as ball bearings and tapered roller bearings; or non-roller bearings, like graphite bearings and bronze bushings, may be used in a rotary union. The bearings are always used to allow a part of the joint, either the shaft or the housing, to rotate
The heart of the rotary union is the seal. The seal prevents the medium from leaking outside the rotary union while in operation. Seal types can vary from pusher-type end face mechanical seal, non-pusher type end face mechanical seal, lip seals, and o-ring seals. Most rotary unions have more than one seal. [6]
Many rotary unions incorporate multiple ports, some of which are designed to handle different types of material simultaneously. A rotary union with a straight port transfers the substance directly through the rotary union. Other designs include an elbow port, which causes the material to flow out at an angle, and multiple ports. A multiple port rotary union looks like a perforated cylinder. At the end of the cylinder is a threaded screw with a seal or seals that lock on to it. The material being transferred flows into the cylinder and out of the input holes. In the case of a rotary union with multiple inputs, chambers separated by seals keep the materials from inadvertently mixing. This type of rotary union is often used in the manufacture of plastics and other petroleum products, for which multiple inputs may need to be streamlined, but kept separate.[ citation needed ]
We can also classify rotary unions according to the media it transfers. For example if it carries coolant, it is refereed as a coolant union. The same is also true for other media like water, air, steam etc.
Many assembly lines incorporate multiple rotary unions, because they are highly versatile and take up less space than other devices designed for a similar purpose. Rotary unions also appear in automobiles and other machines that require constant supplies of lubrication, air, or other liquids in order for moving parts to run smoothly. Brakes, for example, use rotary unions to maintain a constant supply of pressurized brake fluid. Rotary unions are also heavily used in crude oil processing, the chemical industry, commercial food production, and pharmaceutical applications.
Equipment used in grain harvesting including combines, tractors, grain carts and threshers employ rotary unions. Once harvested, many crops will be processed with equipment that uses rotary unions. Food processing equipment that use rotary unions include cooling conveyors, flaking mills, shredders, steam cookers, starch dryers, rotary cutters and roll-forming.
Auto manufacturing is a diverse user of rotary unions for a broad range of parts or components and materials, whether machined steel, iron or aluminum, stampings, plastics, glass or paperboard. Rotary unions are used for operations that require coolant, lubricant or hydraulics.
There are two kinds of car wash facilities that use unions: the automatic and the hand operated. Most manufacturers of automatic systems have several revolving brushes which use 55 series to introduce low pressure detergent water through the supporting shaft to the brushes. In addition, automatic car washes have spinners that require rotary unions to transmit high-pressure water into the spinning mechanisms.
Downstream processing of paper, plastic film, foil and related substrate materials into finished, printed packaging such as bags, pouches, labels, tags, folding cartons and corrugated shipping cases is called converting. Rotary unions are used in all types of converting for water, steam, thermal oil, air or hydraulics.
Rotary unions may be used to transmit coolant, cutting oil, MQL, pressurized air in a bearingless or bearing supported configuration. Besides coolant delivery, rotary unions are used for chucking, tool sensing, rotary index table and other machine tool applications.
Electro-hydraulic equipment used in mining operations employ rotary unions including shuttle cars and coal cars, drill heads, backhoes, clam shell cranes and drag lines. In addition, boom hoists, retrieving drums and bucket drum clutches each require rotary unions.
Drilling rigs (oil or gas) use air clutches and brakes that require rotary unions. Water unions are used to flush mud from the drill tip, and must withstand shock and vibration in this severe application. Oil and petrochemical refineries use batch mixers, flaking mills, blenders and drying rolls that each require rotary unions. The development of subsea oil and gas fields requires specialized equipment. Subsea swivels, manufactured by Dynamic Sealing Technologies, Inc., are designed for deepwater oil production systems that provide equipment operations added flexibility when lowering flowlines in harsh waters down to depths reaching 3,500 meters.
Paper applications span the supply chain from the raw pulp and paper mills, to the downstream paper converters. Mills use steam joint and siphon systems and water unions for heating and cooling. Converters use rotary unions for heating and cooling rolls, as well as winders with air clutches and brakes.
The manufacturing of plastic materials encompasses a wide variety of applications including cast film, blown film, foam, flexible and rigid sheet extrusion, single and multi-layer co-extrusion, blow molding, thermoforming, pelletizing, wire and cable, injection molding and winding. Rotary unions are used for heating or cooling the many processing rolls throughout the wide variety of applications. In addition, rotary unions for air and hydraulic service are used in winding and injection molding applications. Many of today's modern winding applications will also utilize electrical slip rings.
Printing on flexible rolls of paper or plastic films requires rotary unions for air or hydraulics, as well as chill rolls for temperature control. Web offset and sheet printing equipment use many rotary unions on the ink vibrator and chill rolls.
Rubber is compounded on big industrial mixers which use rotary unions for water cooled rolls. Rubber extrusion is similar to plastic extrusion, with rotary unions used to cool the extruder screw.
The steel industry is one of the largest users of rotary unions primarily for continuous casting machines (CCM) which use rotary unions to cool the numerous rolls that support molten slabs as it moves by gravity through various segments onto a run-out table to downstream annealing and heat treating. The slab is formed into coil or sheet. Coil is further converted in processing centers that require hydraulic unions for actuation of mandrels.
The textile industry is a large user of water, steam and hot oil unions. Weaving, dyeing and finishing processes are the largest users of rotary unions.
Rubber tire plants use industrial mixers, extruders, calendar train cooling stacks and rayon slashers to make tire cord. Rotary unions are used in every process for temperature control. [7]
A clutch is a mechanical device that allows the output shaft to be disconnected from the rotating input shaft. The clutch's input shaft is typically attached to a motor, while the clutch's output shaft is connected to the mechanism that does the work.
A pump is a device that moves fluids, or sometimes slurries, by mechanical action, typically converted from electrical energy into hydraulic energy.
Fluid bearings are bearings in which the load is supported by a thin layer of rapidly moving pressurized liquid or gas between the bearing surfaces. Since there is no contact between the moving parts, there is no sliding friction, allowing fluid bearings to have lower friction, wear and vibration than many other types of bearings. Thus, it is possible for some fluid bearings to have near-zero wear if operated correctly.
In mechanical engineering, an end-face mechanical seal is a type of seal used in rotating equipment, such as pumps, mixers, blowers, and compressors. When a pump operates, the liquid could leak out of the pump between the rotating shaft and the stationary pump casing. Since the shaft rotates, preventing this leakage can be difficult. Earlier pump models used mechanical packing to seal the shaft. Since World War II, mechanical seals have replaced packing in many applications.
Cutting fluid is a type of coolant and lubricant designed specifically for metalworking processes, such as machining and stamping. There are various kinds of cutting fluids, which include oils, oil-water emulsions, pastes, gels, aerosols (mists), and air or other gases. Cutting fluids are made from petroleum distillates, animal fats, plant oils, water and air, or other raw ingredients. Depending on context and on which type of cutting fluid is being considered, it may be referred to as cutting fluid, cutting oil, cutting compound, coolant, or lubricant.
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A compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a specific type of gas compressor.
A plain bearing, or more commonly sliding contact bearing and slide bearing, is the simplest type of bearing, comprising just a bearing surface and no rolling elements. Therefore, the journal slides over the bearing surface. The simplest example of a plain bearing is a shaft rotating in a hole. A simple linear bearing can be a pair of flat surfaces designed to allow motion; e.g., a drawer and the slides it rests on or the ways on the bed of a lathe.
On a ship, the engine room (ER) is the compartment where the machinery for marine propulsion is located. The engine room is generally the largest physical compartment of the machinery space. It houses the vessel's prime mover, usually some variations of a heat engine. On some ships, there may be more than one engine room, such as forward and aft, or port or starboard engine rooms, or may be simply numbered. To increase a vessel's safety and chances of surviving damage, the machinery necessary for the ship's operation may be segregated into various spaces.
An O-ring, also known as a packing or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a round cross-section, designed to be seated in a groove and compressed during assembly between two or more parts, forming a seal at the interface.
A dynamometer or "dyno" for short, is a device for simultaneously measuring the torque and rotational speed (RPM) of an engine, motor or other rotating prime mover so that its instantaneous power may be calculated, and usually displayed by the dynamometer itself as kW or bhp.
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.
A coolant is a substance, typically liquid, that is used to reduce or regulate the temperature of a system. An ideal coolant has high thermal capacity, low viscosity, is low-cost, non-toxic, chemically inert and neither causes nor promotes corrosion of the cooling system. Some applications also require the coolant to be an electrical insulator.
A liquid-ring pump is a rotating positive-displacement gas pump, with liquid under centrifugal force acting as a seal.
A rotary vane pump is a type of positive-displacement pump that consists of vanes mounted to a rotor that rotates inside a cavity. In some cases these vanes can have variable length and/or be tensioned to maintain contact with the walls as the pump rotates.
The Suzuki RE5 is a motorcycle with a liquid-cooled single-rotor Wankel engine, manufactured by Suzuki from 1974 to 1976. Apart from its unusual engine, the RE5 is mostly a conventional roadster, albeit with some peculiar styling details thanks to Italian industrial designer Giorgetto Giugiaro.
A hydraulic motor is a mechanical actuator that converts hydraulic pressure and flow into torque and angular displacement (rotation). The hydraulic motor is the rotary counterpart of the hydraulic cylinder as a linear actuator. Most broadly, the category of devices called hydraulic motors has sometimes included those that run on hydropower but in today's terminology the name usually refers more specifically to motors that use hydraulic fluid as part of closed hydraulic circuits in modern hydraulic machinery.
Ferrofluidic seals, also known as magnetic liquid rotary seals, are employed in various rotating equipment to facilitate rotary motion while ensuring a hermetic seal. This is achieved through a physical barrier constituted by a ferrofluid, which is held in position by a permanent magnet. Developed in the 1970s, ferrofluidic seals have been utilized in a range of specialized applications, including computer disk drives, vacuum systems, and nuclear technologies.
A drum motor is a geared motor drive enclosed within a steel shell providing a single component driving pulley for conveyor belts.
An internal combustion engine is a heat engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combustion engine, the expansion of the high-temperature and high-pressure gases produced by combustion applies direct force to some component of the engine. The force is typically applied to pistons, turbine blades, a rotor, or a nozzle. This force moves the component over a distance, transforming chemical energy into kinetic energy which is used to propel, move or power whatever the engine is attached to.