Theexpanding , available at tubes, is a key process step in the manufacture of heat exchangers, steam turbines, condensers, air coolers, and boilers. When selecting machines and tools fortube rolling, manufacturers must consider factors such as safety, speed, cost, required operator skills, repeatability, and overall quality.
Importance of tube rolling
Since, as a rule, a large number of tubes must be rolled into a heat exchanger, condenser, or boiler, it is crucial to use best practices and high-quality tube expansion technology tools fortube rolling. This helps prevent frequent and costly tool changes as well as damage to the tube to be rolled.
The tube rolling process
Inpipe rolling, the tube is expanded using a tube expander so that the Tube inner diameter increases. During this process, the pipe wall is reduced by the expansion and pressed against the inner surface of the bore in the pipe end. The percentage increase in the pipe’s inner diameter from the point where the pipe contacts the bore is expansion rate . Generally, there are two types of rolling:contact rollingandsealing rolling.
Facing rollstypically have a expansion rate between 3% and 5%. Facing rolls are sufficient when the tube is to be applied only after orbital welding to prevent crevice corrosion. The facing itself does not serve a sealing function.
Sealed rolled jointstypically have a expansion rate between 15% and 20%. Sealed rolled joints serve a sealing function and are generally used as the sole tube tube-to-head connection. An exception to this is, for example, titaniumtubes, which must be sealed by rolling before welding. It is important during sealing rolling that the tubes are not over-rolled—that is, the tubes must not be expanded so much that the molecules of the tube material lose their cohesion. The tube material then begins to delaminate, which can lead to leaks in the tube tube-to-head joint.
Optimal equipment for tube rolling
The optimal equipment forexpanding from tubes, particularly the tube expander, always depend on the tube to be rolled and the specific conditions. In general, however, at least one drive machine and one tube expander required. While tube expander come in a wide variety of sizes and designs,pipe rolling systemsare available exclusively in pneumatic and electric versions.
Electric tube rolling systems
Electric tube rolling systems are characterized in particular by their wide range of applications, ease of operation and durability. They consist of the following elements:
Electronic tube expansion controller: Controls the drive machine and, through the precise preselection of the cut-off torque, ensures that the set expansion rate is maintained during expanding.
Electric drive machine: Provides the rotational motion of the tool. High-quality TECHNODATA-drive machines are suitable for virtually all rolling tasks and are optionally available with 42V safety voltage.
telescopic shaft: Connects the drive machine to drive machine tube expander , and ensures maximum ergonomics and workplace safety through its telescoping function and ball bearings.
Assembly Cart: Transforms the electronic rolling machine into a “mobile rolling machine.” Cardan suspension and a swiveling boom ensure maximum ergonomics and flexibility.
A special type of electronictube rolling machineis the mechanical-hydraulic single-roll rolling machine. This single-roll rolling technique, which is used in particular for the expanding from tubes to process high-quality materials such as titanium, consists of a drive machine and a hydraulic cylinder that controls the feed of the tube expander . In addition, special 5-rollertube expander are used, whose rollers are arranged in parallel and which also feature a guide sleeve. This prevents damage to the inside of the tube and allows the operator to precisely control the rolling process.
Pneumatic rolling machines
Pneumatic single-roll machines are characterized by their simple setup and quick readiness for operation, as they require only a pneumatic drive machine and an upstream maintenance unit. A disadvantage, however, is their limited range of applications compared to electronic single-roll systems, as well as the lack of a single-roll controller for simple and precise control of the rolling process.
Best practices for tube rolling
Use high-quality tube expansion technologythat delivers high-quality, consistent rolling results, is easy to use, and ensures ergonomic and safe operation.
Only use tools tube expander with long tool life to minimize frequent tool changes and thus delays in the work process.
Use sufficient lubrication to reduce tool wear and prevent pipe damage.
Check the pipe hardness to avoid cracks and ensure the correct wall reduction.
Ensure that the tube ends is clean and aligned to achieve optimum results.
By following these best practices and understanding the material-specific requirements for wall reduction, manufacturers can ensure high-quality pipe joints and reduce the risk of leaks and the need for repairs.
The Right Single-Roll Forming Technique for Your Application
Which tube expander drive machine are right drive machine your project depends on the tube size, material, and tube end thickness. We can advise you on this and also supply custom sizes for your rolling applications. All machines are also available for rent —with no upfront investment costs and on short notice.