Plant for simultaneous cutting to length of several brake lines

A global manufacturer of commercial vehicles and buses launched a new truck model in which a wide variety of PA lines for brake fluid and coolant are used. As the existing production facilities for processing and machining the PA lines for the existing truck and bus models were already reaching their capacity limits, a new production facility was needed. Metzner Maschinenbau GmbH provided the solution with fully automatic machinery, which offers the customer a multitude of advantages. The line was dimensioned in such a way that it still has sufficient capacity reserves for an increase in production if sales of the new truck model increase.

One of the challenges for the Metzner development team was to achieve the required output quantity for all PA brake tubes installed in the new truck model in different lengths, diameters and quantities with only one production line. In addition, the machinery should always produce complete tube sets which can be clearly assigned to the subsequent assembly stations. The Metzner development team mastered this difficulty by, among other things, a combination of seven unwinders, two production lanes and a suitable storage system, as well as the elaborate allocation of the two processing lanes. This required, among other things, a network connection of the production line to a central database for material requirements. The Metzner production line is now fully integrated into the customer's MES system with automatic order transfer and feedback function.

The production line consists of seven unwinders with associated feeders, of which three or four each load one of the two tracks. If more quantities of one product are required than of another, several winders can be loaded with the same product and, for example, both production tracks can be used simultaneously. The optimal loading of the winders in combination with the appropriate division of the tracks in order to produce the PA brake tubes required for a truck model was determined by the Metzner developers and now enables piece number capacities of 4000 to 5000 tubes per shift.

After unwinding and feeding into the so-called lane changer, which consists of the two production tracks and automatically selects the correct track and guide for the tube diameter to be processed, the material is transported to the cutter unit by means of contact-free loop control and belt feed, where it is cut to length and printed. The high-quality printing is carried out by two or three inkjet printers at up to 1.3 m/second, alternatively by a laser printer. This way, for instance, both tube ends can be provided with insertion markings for tube couplings with an accuracy of +/- 1 mm.

A gripper handling system then loads the finished tubes into the tube magazines arranged on a conveyor belt. After further transport of the material to the removal station, the operator removes the tube sets as loose bundles which are marked accordingly and are ready for further processing in the assembly department.

The machinery can be operated in three ways: in automatic mode, so that several tube sets are produced in succession, in a mode for the production of individual tubes, and in manual mode, where all processing steps can be carried out individually. The main benefit for the customer is that the machinery automatically feeds the material from the feeder to the main machine after the tube bundle has been inserted into the dereeler. Gating and production start are also performed automatically. Production is carried out just-in-time without intermediate buffer at speeds of up to 1.5 m/second.