C. U. W. KELLER GMBH & CO. KG I ZEMENTWERK BURGLENGENFELD (HEIDELBERGCEMENT AG)

High-precision work for main gear replacement on a tube mill

1 The single-stage spur-type pick-off gear with two planetary reduction gears has a total weight of approx. 55 t

2 Pitting damage to the tooth flank of a double helical pinion shaft

3 The building basement in the cement plant was reinforced with 20 t of steel structure to assure safe removal of the main gearwheel

4 A new design solution permitted simplified changing of the ring: the main gearwheel and flange shaft were separated. They had been a single component in the original version. The welding ring and flange shaft could then be separately machined and only joined together again as the final operation

5 The double helical pinion shafts had to be manufactured to match the old drill patterns of the bolted Stoeckicht planetary stages

6 The pick-off gear and planetary stages were dismantled in-situ, the lower housing section remaining on the foundation. New fitting holes in the drive shaft were made with precisely the same offsets as the old holes

7 The old double helical pinion shafts were machined in only three weeks. The original drill patterns and pitch were measured precisely and then incorporated again into the new shafts. The old planetary stages were then bolt-assembled with the new inside pinion shafts

8 The old main gearwheel was replaced with the new one in only eight hours, despite the constricted space in the assembly shop

9 After final assembly, the mill underwent a six-hour test at full load; vibration and trend measurements indicated a significant improvement

10 The two drive trains with medium-voltage motors were aligned by Keller’s chief erector

All Keller GmbH

The Krupp two-chamber tube mill has been in service for more than 50 years

All Keller GmbH

Recent repair and maintenance work on the around 50-year-old Krupp two-chamber tube mill at the Burglengenfeld cement plant confronted Keller GmbH with a number of challenges. A detailed schedule and the company’s many years of design experience nonetheless made it possible to complete these repairs in three weeks.

1 Introduction

The Krupp two-chamber tube mill at the Burglengenfeld cement plant has been in service for about fifty years. It has a diameter of 3.8 m and a length of 14.1 m, thus occupying a considerable portion of the mill building. The layout of this structure has significantly changed since the 1960s, presenting Keller GmbH, entrusted with the repair and maintenance work on the cement mill, with a number of challenges: the constricted space necessitated positioning with millimetre accuracy of the necessary mobile installation cranes. The floor of the shop would not have stood up to the...