Especially the automotive industry has great interest in a flexible production of plastic tubes because it faces a rapid cycle of new product developments. Vehicle concepts are changing quickly, particularly in the e-mobility sector, making new plastic lines for media feed-through necessary. Other manufacturers of plastic lines are also benefiting from a fast production of sample parts.
The HotBend 35 introduces CNC bending technology from metal tubes to the plastic sector. When bending metal tubes, the tube bending machine produces each bend individually. The HotBend 35 uses this sequential process now for the production of bent plastic tubes. The machine operator transfers the geometry of the part from the bending data provided on the drawing to a simple bending table. Deviations of the bent part from the set geometry can be corrected for each geometry element or each bend individually. New geometries can thus be produced at the push of a button. The conversion to a new, previously saved program is easy.
CNC Bending - From metal to plastic
"While metal tubes are being cold-formed, plastic tubes have to be heated before the bending process so that they lose their rigidity. The conventional heating method used by manufacturers is the furnace heating of the tubes in a mold. Thus, the tubes keep their required profile after cooling off", explains Christoph Röhm, Executive Vice President Tube Bending Machinery.
The CNC plastic tube bending machine HotBend 35 enables the bend-by-bend bending of plastic tubes just like it is done with steel tubes. The machine introduces a so far unknown level of flexibility to the production of plastic tubes. This flexibility is particularly helpful when having to respond to changed installation spaces in the vehicle or changes made by the OEMs.
Sequential heating of the bend's flat length
The HotBend 35 does not heat the entire tube but only the area where the bend shall be made. A newly developed heating device is used for this process. It can heat different materials, e.g., PA 12. The tube length to be heated can be adjusted simultaneously. Thus, only the area that shall be formed will lose its rigidity.
Handling of the soft plastic tube
The machine is equipped with a fully integrated robot which handles the soft plastic tube after the heating process.
"The plastic tube is heated for the bending process and is supported by an internal mandrel which prevents a collapsing of the material during the bending process. Therefore, also considerably larger tube diameters can be processed.The heated, soft tube is guided and always optimally supported during the bending process. Due to the fully integrated robot, very long tubes can be bent, additional handling operations are possible", explains Röhm.
Everything in one system
Programming of the robot is integrated in the WAFIOS programming system (WPS) and is quite simple due to the Geometry Input. No separate program is required. The machine calculates all processes based on the tube geometry. No elaborate robot programming is required.
Bending the tubes with an internal mandrel allows thin tube walls and small bending radii with a homogeneous cross-section and a smooth inner surface of the tube that reduces pressure drops of the fluids flowing through the tubes. Thus, the radius of the bend can be just as small as the outer diameter of the tube.
Technical details at a glance
The HotBend 35 can process a maximum tube diameter of 35 mm. The standard version has an infeed length (with internal mandrel device) of up to 2,500 mm. The machine can bend to the left as well as to the right. iQtube also enables a simulation of the bending sequence and robot movements with collision monitoring and determination of the cycle time. Changing from one workpiece to another workpiece with a different tube diameter or different bending radii requires only a quick change of tools, the software takes care of the rest.