2021-07-29
Metal hose installation!
Although metal hoses can be compressed and stretched, if not installed in the right position, they can break quickly and reduce their service life.
Hoses can be mounted horizontally, vertically or diagonally, ideally vertically, and should be avoided near the wheels. Baffles can be installed if necessary.
Generally, metal hose can be divided into three lengths: the first is the compression length, that is, the length of the hose compressed to the limit position; The second is the installation length, which is the length of the hose in the middle of half the maximum displacement; The third is the stretch length, the length of the hose when it is stretched to its maximum limit.
When installing the hose, the hose should be in the middle position, that is, the installation length. When installed at this position, the hose can be moved in two directions under axial load. Otherwise, if it can only move in one direction, the strength of the metal hose will be affected and the service life will be reduced.
In the actual installation process, considering that using a ruler to measure the length of the hose according to the calculated result before installation may affect production efficiency, some foreign manufacturers directly install a ruler on the hose and cut off the ruler after installation.
Metal hose _ bellows _ net sets _ joint structural characteristics metal hose _ bellows _ net sets _ joint structural characteristics: metal hose is generally composed of bellows, net sets and joints three parts. Bellows are the metal hose body, plays a flexible role; Net sleeve plays the role of strengthening and shielding; The joint acts as a connection. For different use requirements, they are connected in different ways: the bellows, net sleeve and joint three parts are connected in the form of welding, called welding type; In the form of mechanical clamping connection, called mechanical clamping type; In addition, there is a combination of the two methods, called the hybrid.
The Corrugated Tube is known as a Corrugated Tube or a Corrugated Box in The Americas, while it is commonly known as Metallbulgen or English Metal Bellows in Europe. This name comes from the old hand-operated air balloon, commonly known as "fur tiger" in China. It is a cylindrical thin-walled shell with transverse corrugation, which can be elongated or shortened under the action of axial tension or pressure; If a transverse force is applied to it that produces a bending moment, the corresponding displacement along the axial plane can be obtained. It is widely used in various technical fields because it can produce a considerable displacement when the characteristics are close to the appearance and the effective area is almost unchanged. The performance of the bellows depends on its structural form, and the structural form varies according to the different manufacturing methods: the electroforming method can obtain the bellows with uniform wall thickness and high precision; The bellows with excellent elasticity can be obtained by welding method; The bellows with large nominal diameter can be obtained by mechanical spinning. The bellows as elastic support can be obtained by machine cutting method. A more comprehensive bellows can be obtained by hydraulic method. At present, in addition to the elastic element, sensitive element and measuring element used in instruments and meters, the bellows are widely used as metal hose body, mainly by welding forming, mechanical spinning forming and hydraulic forming these three methods of manufacturing. There are eight species in spiral and circular categories. Spiral bellows (Hengchang hose Factory), this kind of bellows generally wall thickness of 0.15~0.50 mm, diameter of 2~100 mm. Annular bellows, this kind of bellows generally wall thickness is 0.15~1.0 mm, diameter is 6~500 mm; For special use occasions, there are also made of wall thickness of 10 mm, diameter of 4000~5000 mm of the giant corrugated pipe, they are single layer mainly, but also has the form of double, three or multi-layer structure; Stainless steel is often the main, but also useful carbon steel, copper, aluminum, titanium, copper zinc alloy, copper nickel alloy and other metal materials.
From the point of view of the structure of the metal bellows, the material of the metal bellows has two bell tape and pipe, they can be shaped out of the ring bellows and spiral bellows. Just because the strip formed bellows always have a certain length of brazing or fusion welding buckles and joints, these places often accumulate the residue of the working medium, and precipitate the cleaning test and the mechanical impurities in the working medium to pollute the cavity. Therefore, the reliability of its use is relatively poor. Annular bellows are pipes with special geometric shapes, with the outer edges of a number of annular diaphragm tangentially connected with a number of concave centripetal half rings and the inner edges tangentially connected with a number of concave vest half rings. Its billet is mainly made of pipe. This kind of bellows has the characteristics of large flexibility, good elasticity, simple manufacturing and small rigidity. Suitable for making metal hoses of large and medium diameter which bear general working pressure and require high flexibility. The spiral bellows are pipes of special geometric shape with the outer edge of a certain length of the sprung diaphragm tangentially connected with the centripetal half ring of the sprung concave surface and the inner edge tangentially connected with the half ring of the sprung concave vest. This kind of bellows has the characteristics of high strength, large rigidity, simple manufacture, etc., suitable for the production of high, medium pressure, medium and small diameter metal hoses which require general flexibility and high strength.
net
The net sleeve is made of a number of intersecting metal wires or a number of bursts of metal belt woven in a certain order. It is set on the outer surface of the metal bellows at a specified Angle and plays the role of strengthening and shielding. The net sleeve not only shares the static load of the metal hose in the axial and radial direction, but also can ensure the safe and reliable work of the metal hose under the condition that the fluid flows along the pipe to produce the pulsating action. At the same time, it can also ensure that the corrugated part of the hose is not directly subjected to the mechanical damage of relative friction, impact and other aspects. The strength of the bellows woven with a net sleeve can be increased ten times to dozens of times. The maximum shielding capability can reach 99.95%. The material of the net sleeve is generally the same as the material of the bellows, and there are also two kinds of materials used in combination. Ordinary metal hose with only a layer of net sleeve; Special occasions, there are also woven two layers, three layers. According to the size of the bellows and the different use requirements, it is often made of wire rod with a diameter of 0.3~ 0.8mm or strip with a thickness of 0.2~ 0.5mm. 4~15 wire per share, one strip per ingot. At present, the production of wire mesh sets for 24, 36, 48, 64, large diameter of the bellows, and 96, 120 and 144. The main braiding parameters of the net sleeve are (wire) number m, wire diameter φ, (strip) number m ', thickness δ, as well as covering area A, braiding distance T0, braiding Angle φ and so on. They are an important basis for determining the performance of metal hoses.
joint
The function of the joint is first to connect the net sleeve with the bellows as a whole, at the same time, the joint is a metal hose and metal hose or other pipe fittings, equipment connected parts. It ensures that the medium works properly in the pipeline system. The material of joint is usually the same as that of bellows and net sleeve, mainly stainless steel. In order to reduce production costs, some large diameter metal hose in the transmission of corrosive medium is not strong or non-corrosive, the joint can be made of carbon steel; Carbon steel can also be used for joints of metal hoses working with corrosive media if appropriate measures are taken to avoid contact with the medium. The structure of the joint is generally divided into three categories: screw type, flange type and fast type:
Threaded type metal hose joints with diameter below 50 mm are mainly threaded in the case of high working pressure. After tightening the thread, the inner and outer taper surfaces on the two joints are closely matched to achieve sealing. Cone Angle is generally 60 degrees, but also useful 74 degrees. The sealing of the structure is good, but the concentricity of the two docking parts must be ensured during installation. In order to solve the problems of repeated disassembly, assembly and not easy concentricity often seen in practical engineering, the joint can also be designed to match the cone and the ball head.
The joints of metal hoses with flange disc diameter of more than 25mm are mainly of flange disc type under the general working pressure (see Figure 2-5C). It is sealed in the form of a tenon fit. The looper flange, which can rotate along the radial direction or slide along the axial direction, connects the two bodies under the action of the tension force of the fastening bolt. The structure has good sealing performance, but it is difficult to process and the sealing surface is easy to be bruised. In special occasions requiring quick discharge, the holes through which the fastening bolts can be cut to make quick discharge flange.
Express type joints of various metal hoses with a diameter of less than 100mm are generally used in fast loading and unloading conditions (see Figure 2-5E). It is commonly used fluoroplastic or special rubber made of the "O" seal ring seal. When the hand handle is moved at a certain Angle, the claw finger equivalent to multiple threads is locked; The tighter the "O" ring is pressed, the better its sealing performance. The structure is suitable for fire, battlefield and other occasions where quick loading and unloading are necessary. In a few seconds, a set of joints can be joined or disassembled without the use of any special tools.
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