Production of the heating system or the water supply of plastic pipes is advantageous in that almost all of the work can be done independently, without the involvement of specialists. The cost of materials is low and the necessary expertise is available in the process.
Plastic products do not necessarily require use special rotation angles piping elements. This reduces the volume of work and, most importantly, reduces the resistance to the flow of water in the system.
Features of the construction of metal structures
Products made of metal have a multilayered structure:
- The inner and outer - high crosslinked polyethylene;
- Middle layer - aluminum.
For a lasting connection between the layers using a special glue, so some descriptions can be found no presence of three and five layers, but the adhesive layer only play the role of fastening and are not basic.
Advantages of polyethylene as a material:
- High chemical and biological inertness, ensuring operational safety and durability;
- The high surface smoothness, which reduces the flow resistance of the medium;
- Low adhesion, prevents accumulation of dirt and salt deposits;
- Resistance to the external environment.
The aluminum layer between polyethylene layers increases mechanical strength and reduces the linear expansion coefficient when the temperature of the flowing fluid.
Pipes manufactured from laminates in a wide range of diameters. The most widely used pipe diameters 16, 20 and 26 mm. Less frequently used products with diameters of 32, 40 and 63 mm. Materials are available in shops bays with a length in the bay of 50 - 200 m.
The multilayer structure imposes restrictions on material of metal. What can happen when the wrong bend:
- Stratification. When excessive reduction in bend radius or by several attempts glue seam folding is broken, whereby aluminum and polyethylene layers may lose adhesion between them. This will lead to a decrease in strength and durability;
- Creases. The wall, which is located inside the bending angle may fall within. As a result, the spot crease reduced flow cross-section until the complete overlap. Typically, in the field crease occurs bundle design;
- Cracks outer layer. It is also possible for a small bend radius, but most often occur when attempting to bending of materials at low temperatures. As a result, cracks becomes bare aluminum portion which has a low corrosion resistance.
The first of these defects - the bundle, is dangerous because it is impossible to determine the occurrence of anything outside inspection, so when working with plastic pipes necessary to follow the recommendations.
The occurrence of most defects can be avoided if you follow the basic rule - bending radius composition pipe must not be less than five diameters, that is:
- For tubes of 16 mm - not less than 80 mm;
- For 20 mm - 100 mm;
- For 32 mm - not less than 160 mm.
Methods for bending metal pipes
Pipes can be bent at home in three ways:
- Manually;
- With the use of cushioning materials (springs, wire, sand);
- With the use of specialized tools - bending tool.
All methods have their place, but each has its advantages and disadvantages.
bending the hand
The easiest way, but it requires some physical strength and the ability to precisely coordinate the force of impact. Only suitable for use with the products of small diameters - less than 20 mm. In this way it makes sense to use with small volumes of work. Necessary training to properly perform the bends.
Operating procedure:
- Mark on the product site of the bend;
- Take the tube in his hands to his thumbs touching, arranged inside the intended bending;
- Smooth torque tube is bent through a small angle (less than 20 °);
- Move the fingers a few centimeters further and repeat the action. Than a shorter distance moved his hands, the smoother will bend;
- Actions are repeated until the desired radius.
It is important not to make a lot of effort. No need to strive to fulfill immediately the necessary bend. When this method is easy to obtain a crease defect. Better bend pipe initially somewhat larger radius than necessary, and then dognut to the desired value.
Use of the shock absorber
More reliable results are obtained when using shock absorbers. Especially for flexible plastic pipes are manufactured special springs with a dense arrangement of coils. Before starting the bending spring is pushed inside the area when bending, and further receives the same way as when bent manually. Hands should be placed along the edges of the future of the bend and the force can do more. A spring within the cavity, will not permit the formation of the crease.
For convenience pulling diameter spring coils at the ends is less than the working part, but in addition to one of the ends must first bind the strong cord, otherwise there may be problems when removing spring. For the same reason the diameter of the coils must be one - two millimeters smaller than the inner diameter of the pipe.
Also produced springs for manual bending metal pipes, which are designed to fit over the outer surface. These shock absorbers are more convenient because they allow faster to perform multiple bends in one segment, but the risk of creases are slightly higher.
In the absence of absorbers factory Plastic pipe can bend in the home using improvised means. When performing bending at a small angle and a larger radius, the inner cavity of the tube can be tightly fill the wire segments of suitable length. The wire should be soft, easy bending, for example, copper or aluminum. To the wire can be removed, several segments must be of sufficient length. First pulled out long stretches, and the rest is then just shakes. In this way, you can not do the curves at high angles, because the extraction of the wire becomes difficult.
Sealed one end of the tube, you can fill it with well-dried and sieved sand. Sand (or common salt) acts as a good absorber and allows to perform bending at any angle. This is one of the easiest ways, especially when the amount of work is small, although it should be noted that the bending of the tube filled with sand requires a great effort.
Using the bending tool
The use of specialized tools for bending pipes can significantly speed up the process and almost completely get rid of the marriage.
The basis of the different designs benders use a template to which the product is pressed. The benders crossbow template system mounted on a movable rod, presses on the flexible tube disposed between the template and two stationary rollers. Crossbow design advantage is simplicity of construction, the actuator rod may be either manual or hydraulic.
The design uses a rolling bending tool movable roller which presses the motion bendable material around a stationary template. According to the principle action it looks like a device for seaming lids on glass jars.
Note - the limit bending radius equal to the radius of the template. If rolling bender enables bending pipes with different angles, but strictly one radius, the crossbow makes it possible to perform bending with any radius. This technique is similar to bending the hand, but the use of a template and clips with profile recesses avoids defects on flexing the product.
independent production
Any design is easy to make with your own hands. The main difficulty - production template. It is possible to use the smooth cylindrical workpieces, but bending quality is not very high because of the curved tube section will be different from an even circle. Good results will be only if the videos, and patterns will have a bore equal to half of the external diameter of the product. I.e. bender for metal pipes 16 mm in diameter should have a bore with same diameter. We conclude that the correct tube bender will only work with pipes of the same diameter, and versatile device must have removable clips and templates.
Calculation of the bending radius
By the calculations of recourse in cases where it is necessary to accurately determine the place of beginning and end of the pipe bend. The calculation is simple, and reduces to several actions that will be shown using the minimum bending radius of the tube of 16 mm:
- bend radius - R = 5 * D. In this case, R = 5 * 16 = 80 mm;
- With this radius the length of the entire circumference is 2 * 3.14 * R = 2 * 3.14 * 80 = 502 mm;
- The length of the bent portion depends on which angle will bend tube:
- to rotate 90 degrees, a quarter of a circle, that is 125.5 mm;
- for U-shaped bend - half circle - 251 mm.
Advice
To easily bent pipe, the bending portion need to warm up before operation hairdryer construction. Note - the melting point of polyethylene does not exceed 135 degrees. Heating above this value will lead to irreparable consequences. Many sites meets the recommendation to check the temperature by means of a strip of paper. Charring paper indicates that achieving the desired temperature. However, nowhere stated that the paper charring temperatures above 150 - 200 degrees. Hence it can be concluded that the use of a blow torch or torch for heating is unacceptable, because flame temperature is distributed unevenly and exceeds the minimum values in repeatedly.
Application allows benders to bend the tube with a radius less than the allowable, but preliminary check on the quality of the unnecessary interval of the same batch. The resulting fold sawn hacksaw and carefully examined for the presence of delaminations and other defects. In their absence, can proceed to finish work.
