When assembling the heating system of the stainless pipes there is a need to produce folds and transitions angle for a precise fit pipeline joints. To perform this operation, applies a special device for steel bender. Depending on the scope tube bender can be manually embodiment, for industrial or bending.
Technical features and properties of the stainless steel tube
Stainless steel has a set of remarkable useful properties and therefore widely used in industry, medical industry, in public utilities and households. Its main properties include the ability to withstand corrosive environments, corrosion resistance and high temperature and high mechanical strength.
Such properties acquired through steel chemical composition, whose main element is chromium. In the manufacture of steel and are added other dopants which give the products obtained pleasant smooth appearance.
Important! Stainless steel does not adversely affect the conductivity of the medium, so it is absolutely safe for food and water.
Methods to prevent ovalization
When bending stainless steel tubes, particularly thin-walled, manifested undesirable changes in the shape and thickness of the wall material of the article, in particular:
- changing the external form, appears ovalization;
- there is a reduction of the outer wall thickness due to stretching during bending;
- appearance of kinks and folds on the inner radius of the bend;
- after bending due to the resilient properties of the product increases the bending radius and the angle of rotation.
All these negative consequences affect the appearance of the product, decrease in wall thickness reduces the strength. A ovalization reduces the flow cross section and causes additional resistance to movement of the working medium.
Therefore, to prevent such changes in pipe bending is performed using methods to keep the round shape of the product without deformation. One of these methods is based on the fact that by the inner filling pipe rigid or resilient material protect the inner wall from deformation.
The filler may be used sand, powdered cork, rubber, and even water. To prevent precipitation of the filler during bending, pipe section closed on the two sides of the stopper. To prevent displacement of the outer tube walls are used as external guides the roller.
The best effect is obtained by using as a filler in rigid substance, however, this method is more common. Typically, when bending is applied just two ways of preventing deformation, internal and external, it gives the best effect.
Industrial methods of bending
In an industrial environment, to bend a pipe made of stainless steel, various methods are used: using a bending tool, a method of winding a manner running, rolling, drawing and stretching supports. The use of a particular method depends on the mass production as well as the type and size of the resulting curved end product.
bending benders
For small production volumes or when installing piping systems for heating manual tube bender is used on construction sites. Bender has a low weight and can be easily delivered to the work site. They are available for quick change rollers of different diameter and maximum bending angle is 180 degrees. The screw rod bending tool drives the bending roller, which bends the tube diameter up to 18 mm.
In those places where there are electrical network uses portable electric tube bender for stainless steel. The completeness of delivery includes a large set of different tools for bending different material sizes and bending radii. Adjusting fold speed, the presence of reverse and automatic mode, as well as light weight gives a significant advantage of this device over other benders.
In the absence of electrical networks for operation of the device can be connected battery.
Flexible method of winding
Method of winding a flexible pipe made in special tube bending machines. This method is used primarily for those industries where the need to receive the profiled pipe of high quality with a small bend radius and full invariability wall geometry. This aviation and space industry, mechanical engineering and the manufacture of furniture.
Bending process is as follows: piping is put on a special device called a mandrel, and a clamp attached to a folding roller. A bending roller is rotated with clamping and stretching the pipe, which is wound on the roller to a predetermined bending angle. Inside the product retains the shape of the mandrel products, not allowing her to change section.
Bending using the running
For the construction industry, as well as for the manufacture and piece of small batches, benders are used that produce bending process running. When the work product is pressed to the stream of the fixed roller and securely. Roller burnishing roller are made circular movements, bending of the steel tube to the desired size. In this case the stream sizes rollers must match the diameter of the bendable pipe.
This method is used for bending pipes with large wall thickness, with the bend radius not less than 3,5 D. Changing the cross section at the fold may reach values of 10... 12%. Bending burnishing used when the ovality is not important when using the product. Tube bending machines for such works have a simple and inexpensive device cost.
Rolling
Roller benders are foldable products in the ring arc, and the workpiece can even be bent into a spiral, and you can specify the pitch of the spiral coil. The process of folding into a ring consists of two stages:
- Initially, the machine creates a preload with the product, is given by the curvature and the radius of the bend. Such average interference is made movable roller, when the pipe rests on the two end rollers.
- Flexible pipes are manufactured under the influence of the frictional force that occurs due to rotation of the drive rollers and the workpiece. The tube directs the rotational direction, and occurs at a predetermined bending radius. If when running is impossible produce a given radius, the operation can be repeated with great pressing of the movable roller.
At the 3-roller benders bend radius depends on the wall thickness. For thin-walled pipe bend radius greater -10D, for thick -10D, and a product with a very thick wall can be up-5D.
Drawing
Sometimes you need to make a pipe bending with decreasing diameter. Such a process is called drawing. It is used for products with thin wall. Initially produced by crimping the end of the current diameter. Then crimped end is pulled through a die and is fixed by a clamp to a creasing pattern.
When rotating the template the product is drawn through a spinneret, thus there is a reduction in diameter and is made flexible. With this method of bending the wall thickness is reduced more than with conventional bending.
extension
Very rarely used method of bending stretching method. It lies in the fact that the product ends of the fixed and the average of the impact pressure roller. Wherein the preform is elongated, tapering walls and bending performed by a predetermined angle.
Bending on supports
For bending on the supports used so-called bender type crossbow. The pipe is installed between the two supporting rollers, and force is applied in the middle of the pressure roller by means of a screw jack or hydraulic actuator. With such a stationary device can bend products with a diameter of 350 mm. Issued and light portable arbalety benders that are used for pipe diameters up to 100 mm.
Flexible ways at home
In the production of bending work are two ways to use at home: with a manual bending tool or without using it.
Important! Pipes with the availability of the necessary supply rollers of different diameters facilitates the work, all the more so by changing the rollers, you can bend the products of different diameters.
The apparatus mounted in a vise on the pick rollers and size pipe is introduced between the rolls so that it rested against the abutment end. Next, the handle is rotated the movable roller on the bending angle again check the dimensions and remove the finished product.
Without bending tool can bend pipe using a spring wire section is not more than 4 mm. A spring fixed at an end, and the preform is inserted into a stop for the fixing or can be clamped in a vice, but not to deform the end. Then, the other end is bent at a pre-arranged pattern. After the end of the bending spring is taken out of the product profile.
Select the method of bending depends on many conditions, it and mass production, the quality and the shape of the final product, place of manufacture of works, and the cost of equipment. However, when flexible articles may experience various defect wall thinning, wrinkling and ovality. Therefore, all these factors should be considered before starting work.
