Production of high pressure hoses: 4 stages of production of RVD
The RVT high pressure hose is a flexible part of the pipeline, which is used in hydraulic communications for joining of moving elements and supply to them of working liquids (machine oil, inks, etc.). From the name it is clear, that such products are able to withstand high pressures. They help reduce vibration effects on specific parts of hydraulic structures.
The technology of RVT production depends on the type of product and its characteristics
Varieties of RVD
The simplest, from a constructive point of view, high pressure hoses are hoses, equipped with steel braid. Such products are non-reinforced, however, due to the braid are able to withstand high pressures of the working environment. exept this, there are other RVD, which are worth paying attention to.
Sleeve in braid. It has a high coefficient of flexibility, that allows to use such RVT practically in all modern hydraulic designs. Sleeves, equipped with braid, are used in pipeline designs for supply of working environment under pressure. Such products consist of 3 main layers:
- internal;
- average;
- external.
pay attention! Braided hoses are able to operate in difficult operating conditions. The temperature range of such products is from ?70 to +70 °C.
Rubber hoses consist of several layers of different materials, this gives the product high strength
Rubber spiral hose. The main function of such a device is to supply working fluids (emulsions or oils). Delivery of working liquids is carried out there, where their supply is accompanied by pulses. From a constructive point of view, such sleeves are more complex, than the previous type. Consider the main structural elements, which are part of such hoses:
- outer wire spiral;
- wire spiral, located inside the hose;
- textile layer;
- rubber layer;
- directly textiles.
The complexity of the design of this RVT allows it to perform another important function - the removal of static electricity, arising in hydraulic structures.
Polytetrafluoroethylene (PTFE). Such products are resistant to aggressive chemical compounds. Usually, they are used in structures with medium pressure.
Thermoplastic sleeve. The outer layer of this product is made of temperature-resistant materials. RVT of this type are able to withstand temperatures from ?40 to +100 °C. exept this, it has high strength characteristics.
exept this, RVT is classified into two main types:
- ware, equipped with metal windings;
- braided metal products.
Sleeves in braid - the most popular type of such products
In addition to the above types of RVS, there are others, however, they have a highly specialized operational area and are used very rarely.
Design features of high pressure hoses
To date, the most common are RVT with braid. High pressure hoses consist of separate structural elements. Consider the three main parts, which include these devices:
- bellows part;
- braid;
- tip.
Bellows part is a flexible section of the pipeline, which differs in its ribbed design. There are several options for classifying bellows corrugated pipes. Depending on the structure of the bellows are divided into 2 types:
- consist of one layer;
- two-layer.
exept this, bellows tubes are divided into another important parameter - the shape of the ribs. Depending on the shape of the ribs bellows can be 2 types, namely:
- parallel;
- screw.
Braid is a structural element of most high pressure hoses, which is a metal wire, enhances the strength characteristics of the sleeves.
Useful Information! In accordance with the norms of the thickness of the wire, which is used for braiding RVD, should be at least 0,3 mm. One strip of braid, usually, includes from 6 to 12 wire threads.
The sleeves are equipped with different types of tips for connection to different equipment
In addition to strengthening the strength characteristics of the RVD, the braid also allows them to withstand higher pressures during operation.
The tip is a structural element of a high pressure hose, which performs connecting functions. The tip is a fitting (in some cases a nut) and is used to connect RVT with other parts of communication.
Advantages of RVD
High pressure hoses are different from ordinary pipes, used in hydraulic communications, therefore it is necessary to know their distinctive features. Consider the main technical characteristics of high pressure hoses:
- all structural elements, which are a part of high pressure hoses differ in good resistance to corrosion influences and aggressive chemicals. This allows them to be used in systems, where different liquids act as the medium;
- the inner and outer layers of RVT have good resistance to low, as well as high temperatures. RVT can be used in difficult operating conditions;
- Another advantage of these products is the high coefficient of flexibility;
- usually, fittings and crimping of hoses, used in systems with high pressure, are of good quality;
- high quality sealing elements, used in the installation of RVD, is also a guarantee of reliability;
- good resistance to mechanical influences.
Such products are popular in various operational areas. Consider some of them:
- metallurgy;
- oil industry;
- chemical production;
- construction sphere.
The process of manufacturing sleeves involves several stages, the sequence of which is strictly adhered to
Making high pressure hoses is a serious event, which takes place in 4 stages:
- Preparatory stage.
- Obtisk.
- RVT test.
- Applying special markings.
Preparation for the manufacture of high pressure hoses
Before you start making high pressure hoses RVT, it is necessary to carry out preparatory work. Preparation for the production of RVT includes:
- selection of structural elements for the implementation of such hoses;
- adjustment of production equipment.
Importantly! Fasteners (fittings) for high pressure hoses are selected depending on the cross-section of the product. The choice of adapters and various adapters also depends on this geometric parameter.
Next you need to focus on the size of the fitting, pick up special parts - crimping cams. After preparation of compression cams adjustment of a compression press on the necessary diameter is carried out. The next stage is the preparation of the trimming machine and trimming of high pressure hoses. This is a necessary process, by means of which receive products of necessary length. Cut, made using such a machine, it turns out as smooth as possible, which is very important for further manipulations. If necessary, the ends of the RVT are additionally cleaned.
If necessary, the sleeve is stripped on a special hoisting machine
Then you need to remove the outer layer from the hose, which consists of rubber. Removal of a rubber layer is carried out before braiding by means of the special machine, which is called okorochnym. Not all types of hoses require rubber stripping (example, for 2SN sleeves).
In parallel with the removal of the rubber layer is going to nipple coupling. Further, this connector is placed on a high pressure hose, and then fittings of the necessary sizes are inserted, previously selected for a particular RVT. In the end, the installation of crimping cams in the crimping machine. So, preparatory work for the production of high pressure hoses is being carried out.
Obtisk
After the preparatory work is behind, you can start directly to the production of high pressure hoses RVT. The main stage of manufacturing these products is crimping, which is carried out on special equipment, namely - crimping machines. It is recommended to check the equipment for serviceability before crimping. To date, there are two options for crimping RVT:
- longitudinal method;
- transverse method.
Longitudinal. This RVT compression option is used, usually, in more developed European countries, however, and in Russia it is also found. The longitudinal method of production allows to obtain both varieties of these products (braiding and winding). The production technology in this case involves the use of a coupling, which has annular teeth. The ring teeth are located on the back of the part, which allows you to firmly fix the hose when crimped.
Necessary fittings are installed on the sleeves using the crimping procedure
High sealing performance is achieved by mechanical action on the hose. РВТ, obtained by this method, usually, used in hydraulic structures, which are characterized by high pressure.
Transverse. Domestic production of high pressure hoses in most cases involves the use of the second method - transverse. This method allows you to make braided products. The technology of this method involves the preparation of special crimp couplings, which is pre-processed on the machine. This treatment allows you to remove a layer of rubber from its surface. This is followed by direct transverse compression. Squeeze-type cams, in which the hose is fixed, compress it and as a result on a surface of a hose the pattern is formed, resembling a ladder.
Useful Information! РВТ, which are obtained by the transverse method, are of democratic value and are used in constructions, where the working environment is under no more pressure 12 MPa.
Testing and marking
Testing is a necessary step in the manufacture of RVT. It has to do with that, that the finished product must be checked for quality. This check allows you to identify poor quality hoses. High pressure hoses must meet existing state standards.
Before the start of test work, usually, finished products are inflated. This is necessary for that, to clean them from dust, dirt and other foreign elements. After blowing the hose, it is connected to the necessary test equipment, which is responsible for supplying the working medium under pressure, exceeding the normal operating approx 2 times. Oil or water is used as the working medium during the tests. If the hose has withstood the required pressure and there are no cracks or other defects, then it is considered usable. After the inspection, the hose is cleaned again with air.
At the last stage, a special marking is applied to the sleeves. After marking, the finished products are sorted and packed for storage or transportation.
