Pipe-end processing plant

Fully automated manufacturing cell

  • Face machining of steering tubes, pipes, shafts and rods at 5 stations
  • Optimised for different tube diameters and lengths
  • Finished workpieces in 37-second cycles
  • Chip-free output
HK-CON Rohrenden-Bearbeitung

More info on workpieces

End machining of steering tubes

Varying pipe lengths and diameters, thread sizes, cross groove diameters and depths, slot widths and lengths

With their driven tools, the five sequential machining stations of the linear processor carry out the end-face machining of steering tubes, pipes, shafts and rods from the blank to the finished part with maximum productivity. Starting with the first machining station, the following tasks are performed:

  Planing, chamfering and ring groove production

  Transverse groove production

  One-sided/double-sided slot production


  Cutting the thread and flushing to remove chips

The unmachined parts are axially and radially aligned in the loading station for defined insertion of the steering tubes into the machining stations. A turning device in conjunction with a laser ensures the radial positioning of the parts, which is necessary, among other things, when machining the tube ends on both sides by loading them twice. The two centrally clamping hydraulic power clamping blocks of each station take over the high radial and axial cutting forces during machining and thus, with reference to the tools, result in the machining position.

The horizontal steering tubes are transported between the stations with the 2-axis NC-controlled lift-lower conveyor. From the loading station to the removal from the deposit station by the industrial robot, 12 universal grippers, 2 grippers per position, are installed on the lift-lower conveyor for this purpose. The arrangement of the grippers and clamps ensures the reference position from the start of machining to the end. The pipe is held continuously. Every 37 seconds, with each cycle, a finished part is discharged. The blank bunker in conjunction with the step conveyor, the linear cycle and the final loading robot, which deposits the finished parts on 2 transport pallets via the drip-off station, result in the fully automated production cell for the competitive production of steering tubes in wet machining.

Pipe end machining plant (illustration)

Pipe dimensions

Lengths: 400 mm – 2 500 mm
Diameter: 36 mm – 62 mm
Reducing lengths: 60 mm – 120 mm
Thread lengths: 40 mm – 130 mm
Thread min.: M24x1,5 RH/LH
Thread max.: M40x1,5 RH/LH
Slot depth max.: 80 mm
Slot width: 4.00 mm; 4.5 mm
Cross groove diameter: 5.5 mm – 14.5 mm
Ring groove diameter: 8.5 mm – 14.5 mm
Weight: 500 g – 35 000 g


Simultaneous machining of 5 pipes

Product change from parts family without conversion

Cycle time 37 seconds

Drip-free prefabricated parts

Parts free from chips

Storage directly in customer pallets

Experience the pipe end machining plant in action


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Highest precision and speed

Beladebunker Rohrenden-Bearbeitung

The loading bunker with step conveyor


The unmachined parts are deposited by the operator individually or as a bundle of unmachined parts in the parts bunker of the loading system. An adjustable wall is used to adapt to all tube lengths. After activating the loading function, the step conveyor transports the workpieces to the loading station.

Beladestation mit Dreheinrichtung

Loading station with turning device

Loading station

This station aligns the tube in length and rotational position for transfer to the reciprocating-lowering conveyor and thus for face-side machining.

Simultane Bearbeitung von Kurzrohren an 5 Stationen

Simultaneous machining of short tubes at 5 stations

Rohre im Hub-Senk-Förderer

Tubes in the elevating-lowering conveyor for transfer to power clamping blocks

Transport and parallel processing

The 2-axis NC-controlled lifting-lowering conveyor (own design) transports 6 pipes sequentially with each cycle from the loading station via the 5 processing stations to the deposit station. The workpieces are precisely positioned in the hydraulic clamping blocks of the processing stations.

  Facing head with 5 cutting edges

  End mill HSK 50

  Slot cutter 2 x HSK 80

  Deburring cutter HSK 50

  Thread tap HSK 100

During the cutting cycle, the machining area is separated from the transport area by a bulkhead.

Eine saubere Sache: Spanfrei gespültes Rohr

A clean thing: Chip-free flushed pipe

Thread cutting and rinsing in one station

Chips in the tubes are flushed out with cooling lubricant at this station during thread cutting and afterwards from the opposite side. The removal robot automatically replaces suitable flushing tube adapters with workpiece change.

Auf dem Weg zur Qualitätsprüfung

On the way to quality inspection

Measured part ejection

After cleaning the workpieces, there is the option of a measurement ejection: the robot places the workpiece to be inspected on rotating prism rollers, which transport the tube to the flap of the measured part output. If all measurement results are within the tolerances, the measured workpiece is reinserted.

Simultane Bearbeitung von 5 Werk­stücken bei geschlossenem Schott

Simultaneous machining of 5 workpieces with closed bulkhead


Measured part ejection

Abtropftisch mit Spülrohradaptern

Draining table with rinsing pipe adapters

Deburr and drain

The rinsed pipe is removed from the deposit station by the robot. Before it is placed in the draining table, 2 rotating brushes deburr and clean the thread.

Das Tor öffnet sich: fertig zur Entnahme

The gate opens: ready for removal


After dripping, the robot stacks the finished workpieces into two ready pallets. Rolling gates secured with light curtains are opened with push buttons to remove the fully loaded pallets with lifting trays.

Standard equipment

  • Pipe section bunker
  • Step conveyor
  • Loading and alignment station
  • 5 simultaneous processing stations
  • Lift-lower conveyor
  • Unloading handling via robot
  • Cooling lubricant system
  • Chip conveyor
  • Hydraulic system
  • Extraction system

Special equipment

  • Tool breakage monitoring
  • User interfaces
  • Machining on both sides in one pass
  • Complementary machining stations

Machine dimension

  • Machine tool incl. periphery:
    9 550 mm x 7 350 mm

With the kind permission of the
Clamping and gripping technology
Bahnhofstraße 106–134
D-74348 Lauffen/Neckar

Technical report: Automated machine loading

Variable pipe end machining in three-quarter minute cycles

Special ideas require special solutions – according to this motto, HK-CON GmbH Maschinenbau from Fulda has developed a modular, flexible machine for the efficient machining of pipe ends. With a cycle time of 46 s, pipes with variable lengths and diameters pass through a total of five fully automated processing stations per side. Application-specific high-performance clamping devices and low-maintenance grippers from SCHUNK ensure accurate part handling and reliable clamping in demanding 24/7 operation.

Shafts, tubes, drill rods, steering rods, piston rods – the range of applications for the tube end machining machine from HK-CON is extremely broad. No wonder: without changing the machine and without changing jaws, tube lengths from 400 mm to 2700 mm and diameters from 36 to 63 mm can be machined. If the parts vary, only the tools and the programme have to be changed. “With modifications, it is possible to realise the same machine concept for pipes with diameters of 400 or lengths over 6m,” explains HK-CON Managing Director Walter Kraft.

The pipes are supplied via a feeder, placed centrally by a robot, moved against a stop, transferred from station to station by three SCHUNK PGN-plus universal grippers in each case according to the principle of a cycle line and precisely centrally clamped in SCHUNK power chucks specially modified for the application. At HK-CON’s own machining modules, which have already proven themselves many times over in other machine concepts, the parts are drilled, planned, turned and milled as well as provided with transverse grooves, slots or threads, depending on the requirements. As soon as the first side has been machined in five stations, for example, the transfer to the machining modules of the second side follows immediately with the next cycle, where either the identical machining steps take place or a modified sequence is possible.

Schunk Kraftspannblöcke

Machining 1: The power clamping blocks based on SCHUNK ROTA 2B-400 lathe chucks combine high clamping forces with a large stroke and a compact design. Machining is carried out with powerful and proven HK-CON modules.

Dicht gepackte Schunk Kraftspannblöcke

Machining 2: The individually designed SCHUNK clamping blocks are tightly packed in the working area of the machine. If the range of parts changes, only the tools and programs are exchanged.

50000 N Spannkraft

Machining 3: 50,000 N clamping force with a stroke of 26 mm per jaw and extremely compact design define a new benchmark in terms of the combination of jaw stroke, clamping force and installation space.

Force- and stroke-optimised clamping blocks in central function

To ensure that the transfer of the pipes and their machining does not come to a standstill in fully automated operation, HK-CON has equipped the machine with a large number of SCHUNK grippers and clamping devices. The elementary centrepiece is ten centrically clamping high-performance clamping blocks. “We need a high clamping force to hold the pipes securely, and at the same time a large stroke to cover as wide a range of parts as possible,” emphasises Walter Kraft. High clamping forces are required especially for boring, threading and facing so that the tubes do not rotate or change their axial position during machining. In intensive detail work, the team at the SCHUNK Competence Centre for Turning Technology and Stationary Workholding Systems in Mengen realised a narrow, stationary power chuck with high clamping force and at the same time large jaw stroke individually for the application at HK-CON. The basis was the 2-jaw lathe chuck SCHUNK ROTA 2B-400.

For the first time, it has become possible with this chuck to realise a powerful and at the same time variable clamping of tube ends in a confined space without the need for a modification of the chuck. Long piston guides ensure precise workpiece centring; long base jaw guides ensure optimum jaw support. Clamping takes place almost directly in the area of the guide, allowing an optimum ratio of long guide track and short lever of the clamping jaw. Adjustable brass wiper strips seal the base jaws and protect the inner workings from chips, dirt particles and cooling lubricants. Functional parts hardened and ground on all sides ensure high precision and a long service life of the power clamping blocks. The result is impressive: 50,000 N clamping force with a stroke of 26 mm per jaw and compact design define a new benchmark in terms of the combination of jaw stroke, clamping force and installation space.


Loading 1: Three multi-tooth guided SCHUNK PGN-plus universal grippers on NC-controlled axes take over the loading of the individual stations. This way, even pipes with more than 2500 mm can be handled precisely.


ROTA 2B special solution: The power clamping blocks individually developed for the application based on SCHUNK ROTA 2B-400 lathe chucks define a milestone in stationary clamping technology.

SCHUNK Universalgreifer

Loading 2: Sealed SCHUNK PGN-plus universal grippers support the workpiece clamping during machining. The working area (open here) is completely closed during machining.

Synergy of clamping technology and gripping systems

According to Walter Kraft, SCHUNK’s reliability and competence were the main factors in the decision to entrust the project to them. HK-CON had already realised innovative solutions several times in close coordination with SCHUNK technical consultant Bernhard Ferenz. “We were convinced that SCHUNK could realise vices with such a large stroke and such a large clamping force,” says Kraft. In addition, HK-CON benefits from the unique synergy of clamping technology and gripping systems, which only SCHUNK offers to such an extent. Thus, in addition to the ten individually developed SCHUNK power chucks, 20 sealed SCHUNK PGN-plus 200 universal grippers for supporting workpiece clamping, 36 spring-actuated SCHUNK PGN-plus 200 as lifting devices and two SCHUNK PGN-plus 200 for tube handling between left and right tube machining are used in a tube end machining machine with two times five machining stations. “At each station, we use three SCHUNK grippers for transport and two sealed SCHUNK grippers for supporting workpiece clamping,” explains Walter Kraft. All grippers and clamping blocks are equipped with prism jaws that ensure centric clamping and cover a large diameter range. In addition to the 50,000 N clamping force of the clamping block, the two support grippers add another 7,000 N clamping force.

Optimale Zugänglichkeit

Optimum accessibility: Both the loading grippers and the support grippers are positioned below the workpieces. This allows free access from above.


Translation station: At the translation station, the pipes are transferred from the first to the second cycle line. Here, too, the workpieces are permanently clamped so that an exact axial position is always guaranteed.


General view: A total of ten SCHUNK power clamping blocks and 58 SCHUNK PGN-plus universal grippers were installed in this version of the pipe end machining machine from HK-CON. In combination with 31 NC-controlled axes, the machine enables maximum flexibility.

Focus on process reliability and flexibility

“The principle of ‘better safer than cheaper’ applies to our machines, because process reliability is absolutely crucial,” Walter Kraft emphasises. “Or to put it another way: the system must simply run.” HK-CON consistently paid attention to a sealed workspace, sealed grippers and robust clamping devices. Both the clamping blocks and the axes have central lubrication and most of the drive motors are water-cooled. In addition, the machine was designed in such a way that the chips do not get caught and are well discharged. To ensure that the pipes are free of chips, they are flushed from behind during machining. “Apart from tool and programme changes, no operator intervention is required during regular operation,” emphasises Kraft. A total of 31 NC-controlled axes ensure maximum flexibility in process design and part transport. Thus, the acceleration, speed and pick-up height can be varied individually depending on the workpiece. To ensure that the axial position of the tubes is reliably maintained, they are permanently clamped by one or more clamping devices during the ongoing process. Even when transferring from machining the left to the right side, the position is precisely defined. Thanks to the modular design, the number of machining stations, tools and axes can be expanded or reduced modularly depending on requirements.


Feeding: The power-tight SCHUNK PGN-plus universal grippers are almost maintenance-free. Their patented multiple guidance ensures optimum force flow and minimal wear.


PGN-plus: The lifting grippers are mounted on NC axes. This means that the speed and path can be flexibly varied during part handling without operator intervention. Thanks to the prism jaws, the grippers and clamping devices cover a wide range of parts without the need to change jaws.


Transmission grippers: Even in the event of a sudden drop in energy, the pipes remain securely clamped in the spring-loaded SCHUNK PGN-plus universal grippers.

HK-CON Geschäftsführer Walter Kraft und SCHUNK-Fachberater Bernhard Ferenz

During the development of the machine concept for highly flexible tube end machining, HK-CON Managing Director Walter Kraft (left) was actively supported by SCHUNK technical consultant Bernhard Ferenz (right).


HK-CON GmbH Maschinenbau from Fulda develops, designs and manufactures automated, multi-axis CNC turning and milling centres for individual large-scale production. The basis is formed by modular production units that are flexibly and economically combined with the respective optimal technologies for the most diverse applications. Single- and two-spindle solutions can be realised with the HK-CON modular system as well as applications with driven tools for drilling, milling, turning and grinding. All HK-CON machines are designed for highly productive, automated operation. They can be fed as bulk material or by a handling system. The company employs around 60 people.