High quality machining of gear parts May 2020

Nowadays modern trucks are almost exclusively equipped with automatic transmissions. While on one hand more compact, lighter and more powerful gearboxes are required, on the other hand durability should be ensured even in extreme areas of application.

Transmission parts such as sliding rings, synchronizer rings and ring gears make a decisive contribution to the quality of truck transmissions and to increasing drive efficiency. Therefore, their processing must meet the highest standards.

This process is described below using the example of a new press quenching line from Wickert’s WFH-3-300 series: The system has a component input memory with 3 cells, since it is a 3-station press quenching system. The components are removed from the pallets in multiple layers by robots with the aid of a camera. The robots manipulate both the components and the layer separators.

The still unhardened gears are then cleaned in a pre-washing system (removal of residual cooling lubricants and possible shavings).

A transfer handling system transfers 3 components simultaneously onto a furnace pallet, which in turn is transferred to a 6-stage carburizing ring hearth furnace using a furnace manipulator. The furnace consists of a total of 36 segments. Each segment has 6 furnace pallets, which can hold 3 components each. This means that 648 components can be in one furnace at the same time.

The quenching press from Wickert Hydraulic Presses has a clamping force of 300 kN. As soon as a furnace pallet has been positioned in front of the press, handling quickly transfers the hot components into the hardening tool, while at the same time the hardened components are transferred to a downstream cooling basin, where they can cool down another cycle in the hardening oil.

The fixtures close, hold the component level with individual and component-specific pulse processes and enable the component to shrink onto the tool mandrel.

After the cooling cycle, the mandrel is pressed-out downwards through a press-out cylinder and the tool opens. The result is a hardened component with precise manufacturing geometries, e.g. high-precision inner diameter, but also high-precision cylindricity, roundness and flatness.

Component-specific tools to be added are automatically preheated and replaced by a tool changing device at the specified time. The main advantage is a high degree of utilization of the system with no downtimes due to set-up tasks.

The components are then cleaned in a 2-stage cleaning system by centrifugal force from the hardening oil and the oil is returned to the hardening oil circuit.

The components are then cleaned in a wash box with a water circuit with cleaning additive, so that they can then be transferred to the continuous tempering furnace by handling or, depending on the severity of the test, can be stored in an SPC lock by handling.



AGTOS blasting technology

After the parts have been tempered, they are transferred to the cleanliness blasting system by a 6-axis linear system. This is an AGTOS satellite rotary table blast machine of the type SDH 1500. It has four high-performance turbines, each with 22 kW drive power. These throw an operating mixture of round abrasive at approx. 88 m / s onto the workpieces, which reliably removes the hardness scale with a high degree of coverage. The clean blasted parts leave the machine free of abrasive.


Features of the high performance turbines

Type TA 4.6 high-performance turbines are used in the blasting process. It is a robust housing with single-disc blasting wheels. Each blasting wheel is equipped with six pluggable blades. The advantage of single disc blasting wheel lies in the fact that they have fewer wear parts than double disc wheels. This means less assembly work and lower costs in the case of maintenance and repair work. Further information on the TA 4.6 high-performance turbine is available here

The advantageous flow properties of the AGTOS high-performance turbines guarantee a high abrasive throughput and thus excellent blasting performance. The hot spot, i.e. the area to which the abrasive is applied, is long and uniformly pronounced, which leads to the best blasting results.

The abrasive goes through a cycle. After the blasting process, it is collected, cleaned and fed back into the process in doses.

Not only the manganese casing of the high-performance turbines, but also the blasting chamber itself is optimally protected from the abrasive effects of the blasting agent by means of easily replaceable wear plates.


Further processing of the gear parts

After the blasting process, the components are fed into the output buffer system, where they are then inserted into the individual pallets by a robot.

Wickert Hydraulic Presses has configured the automation, but above all has taken over the coordination of all mechanical and electrical interfaces to the system partners and the customer's building infrastructure, so that a corresponding overall system layout has led to trouble-free subsequent assembly and overall commissioning of the system.

By overarching planning of the safety areas of the entire system, it can continue to produce in some areas, while in other parts of the system, for example, regular maintenance can be carried out.


Clarity / usability of the system:

The HMI of the Wickert main control system makes it easy to localize faults.

Thanks to a step-by-step user interface, system states can be quickly learned and easily restored. This reduces operator errors.

If necessary, an encrypted, secure remote connection can be used for remote maintenance. With component tracking in the Wickert main control system through the complete system manufacturing process, each component receives process information step by step with ongoing processing status, logged quality data are transferred to a higher-level quality MES system when the Wickert PLC leaves the system.

If a component experiences a processing state that lies outside the set tolerances, the component is rejected. This ensures that only "good parts" leave the system and thus reliably supply the downstream production step after the system.

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