The production of a large volume of parts with extremely high quality has been a key feature in the production of automotive transmissions for decades. Developments in both the marketplace and technology, however, are continuing to change production at a very fast pace. For example, the demand for cars has been rising. This increase in quantity is pushing the production volume of gears even higher.
At the same time, the competition from new market participants in Asia is intensifying. What can the transmission builders of OEMs and suppliers do in their production areas to address these developments?
Multifunctional machines that perform an array of hard machining processes on the transmission components in succession are able to provide such a solution. Emag, with expertise in turning and grinding, have provided an option called the VLC 200 GT. This machine was developed for the chuck machining of automotive gears.
Innovation In Transmission Design
The VLC 200 GT uses a variety of process combinations for
the hard machining of checked components.
The automobile industry is continuing to spend more money on research, and annual increases of between seven and eight percent in this area have long since become standard. OEMs and suppliers in Germany alone recorded more than 34 billion euros (US$36.5 million) in development expenses in the past year, according to a study by the German Association of the Automotive Industry.
One of the main focal points of this dynamic innovation is the transmission design. Today’s transmissions are generally becoming smaller (and therefore lighter), but can simultaneously offer more gear ratios and therefore have more gears and gearing components. This produces optimum speed ranges, and reduces fuel consumption.
Each individual gear must be manufactured extremely quickly and very precisely. Given the high unit volumes, the production technology is virtually always a concern for production planners. They try to find solutions that reduce processing time and unit costs, while still continuing to increase the quality of the parts.
Nearly 20 years ago, the first pick-up machine for the combined turning and grinding machining of chucked parts was developed. Its key feature was the combination of the two machining processes in rapid alternation, based on the shape of the workpiece and the quality required.
Building on this, the VLC 200 GT has focused on enhancing productivity, especially in the machining of automotive gears. Guido Hegener, managing director of Emag, explained the approach: “The high unit volume and quality requirements of gears make them ideally suited to our approach.”
Complete Process, Including Dressing
To start, the machine is loaded at high speed by the integrated pick-up spindle. Once the spindle with the part reaches its machining position, the process starts with hard pre-turning of the shoulder and the bore hole in quick succession.
Only a few micrometres of material are then left to be removed from the gear. That means the subsequent grinding process, using either aluminum oxide or CBN grinding wheels, takes significantly less time.
Meanwhile, the machining quality also benefits from the combination of turning and grinding: when there is only a small amount of material remaining to be ground away after turning, the specifications for the grinding wheel can be based more precisely on the end quality required. As a result, surfaces with an average peak-to-valley height Rz of less than 1.6 micrometres can be created.
In addition, this multifunctional technology offers users a multitude of possibilities, such as internal and external grinding spindles, scroll-free turning tools, block tool holders, and a 12-station tool turret, which can all be installed as required.
Tool Cost Savings
There is an additional advantage in terms of tool costs, because during this process the grinding wheel wears down more slowly and therefore does not need to be dressed as often. When it does need dressing, the machine has a separate diamond-coated dressing roll designed specifically for this. To ensure sustained process reliability and high machining quality, the integrated measuring pin is used to check the diameter and length of the clamped component at the end of the process.
Operator comfort and ease of access were also important priorities, so large doors allow easy access to the machining area. The tools and clamping devices are easily accessible and can be changed quickly and conveniently.
Dr Guido Hegener, managing director of
With a small footprint and the ability to flexibly integrate into interlinked factory systems, the machine can be incorporated into a plant’s production system with the aid of a variety of automation systems.
One option for this is the TrackMotion system. This automation system handles transportation from machine to machine with functions such as part gripping, positioning, and flipping of the workpiece.
“On the other hand, there is also the option of using the machine as a stand-alone machine with simple O-belt automation. This is an appealing alternative for many customers in the Asian markets especially,” Mr Hegener added.