Deutsch
Rösler North AmericaVibratory finishing and shotblasting with one process technology
The automotive industry is making ever increasing demands on their suppliers at ever decreasing intervals. What will count in the future more than ever before is efficient exploitation of existing potentials as well as continual improvement of product and process quality. This will require optimisation of the engineering and production structures with competitive costs, higher degrees of flexibility, perfect quality and adherence to schedules.
Vibratory finishing and shotblasting with one process technology
The automotive industry is making ever increasing demands on their suppliers at ever decreasing intervals. What will count in the future more than ever before is efficient exploitation of existing potentials as well as continual improvement of product and process quality. This will require optimisation of the engineering and production structures with competitive costs, higher degrees of flexibility, perfect quality and adherence to schedules.
Getrag SynchronTechnik GmbH from Oberstenfeld (Germany) recently introduced a combined vibratory finishing and shotblasting unit for descaling and deburring sensitive synchro rings. The aim is to achieve the most efficient and thus most economical results of the best quality by exploiting synergy effects. Getrag, a supplier to the automotive industry, has specialised in car gears and within this area is one of the most important partners supplying the automotive industry. This industry expects excellent quality of products and service from its suppliers as well as competitive pricing. Reliable, process security of one hundred percent process is demanded for every production step.
The Application
In the past the synchro rings were surface treated in a shotblasting unit. The components were mainly descaled in this process. Due to the increased demands on quality, an independent deburring process is necessary in addition. There was no question of processing in two separate, individual units (vibratory finishing and shotblasting units).
The two units would not have only taken up much more space but valuable time would have been lost through transferring the components from one unit to the other.
For this reason, the management at Getrag decided for a combination system which was planned and custom-made by Rösler Gleitschlifftechnik of Untermerzbach for the specific demands on the processing of synchro rings. The company had expressly looked for a manufacturer of vibratory finishing and shotblasting equipment in order to have a competent contact for both surface-treatment technologies.
Special requirements
When configuring the system, a space-saving design or a shape that fully exploited the limited space available was to be taken into consideration and, in addition, the system was to operate without manual intervention. From the technical process point of view, attention was to be paid that the individual components had to be processed very gently, without contacting each other and able to be processed from all sides. Absolute process security was also essential.
These specifications were the starting point for the work of Rösler's process technicians. The aim was to work out a process equipment solution which fulfilled all the requirements and demands of the customer.
Even the first results were that good that Getrag was able to make the decision to take the recommended system combination immediately.
The processSynchro rings of various sizes are continuously descaled and deburred running through the combination of systems. It consists of an RBD 500 conveyor continuous blasting unit and an R 425 / 4600 DA continuous flow unit (picture 1). The components coming from heat treatment are washed and transported to the conveyor continuous shotblasting unit using handling equipment where they first run through a pre-chamber and then the shotblasting chamber on a special conveyor (perforated special rubber belt).
In order to keep the components stable in their positions and to prevent them from touching each other they are placed individually in holders (locating devices) on the belt. They are fixed in their positions laterally by raised guides and in the longitudinal direction by ridges. This also ensures that the components are turned precisely component by component instead of being mixed together. The time cycle is regulated by sensors. In the event of irregularities the belt stops for a short time for safety reasons.
Belt continuous shotblasting unit for targeted, gentle processing. The shotblasting unit (picture 2) has two transport belts running in opposite directions on the same level. On the first belt the components are transported into the shotblasting chamber where a hot spot is targeted exactly to this belt area. The spot of the second turbine wheel opposite is likewise reached on this route. Subsequently the components reach the component turning device through an after-chamber (picture 3). Here the individual synchro rings are turned 180 degrees holder by holder and automatically placed on the part of the belt running in the opposite direction and transported back through the shotblasting chambers.
A very fine, round steel grain is used as blasting shot. Automatic blasting shot dosing ensures that a uniform working mixture is always available. After the components have been shotblasted on both sides, they are turned once more, freed of loose blasting shot remains and subsequently transported on a steep belt conveyor into the vibratory finishing machine (picture 1). The sharp edges are removed (radiussed).
Continuous process vibratory finishing
The continuous principle is also applied for vibratory finishing in order to ensure uniform, non-contact processing with a high throughput. The R 425/4600 DA continuous flow unit has a large process chamber, the length of which is selected in such a way that it takes only approximately 20 minutes for a component to pass through.
Special inclination technology of the process chamber makes optimum adjustment of the residence time to the number of components arriving from the shotblasting unit.
The components are transported into the machine in cycles of seven seconds and run through uniformly at a safety distance, flowing in the abrasives (chips). This ensures that they cannot damage each other during processing. The U shape of the process chamber rounded on one side promotes optimum rotation of the chips and components.
During the deburring process the abrasives can reach down to the base of the teeth of the components to remove the roots of the burrs. The components are removed without difficulty in the large-area screening deck. A water spraying system arranged above and below the screen deck ensures that only completely clean components leave the unit.
Likewise the screening deck separates the chips from the components. Subsequently the abrasives are transported onto the lateral vibratory conveyor on which residual water and component cuttings are shaken off over the replaceable sieve segment section. Residual liquids are collected over the entire area above the drip pan and taken away. The components are rinsed during the separation process and then run through a hot air belt drying unit from where they are taken off by a handling device.
The process water required is collected in a collecting tank via outlet pipes outside the machine and cleaned in an integrated water re-circulation centrifuge and fed back into the process again.
Results and potential
The combination of vibratory finishing and shotblasting in one machine, with one process technology, can increase performance, economy and secure processing in surface treatment, as shown in the example. Because the demands put on the component performance are becoming ever greater and ever more differentiated, this is a decisive line for the future for securing the production specifications and strengthening the system partnership. In this regard Rösler does not only provide a wide range of process technological know-how but a great advantage being both technologies from one source, which excludes the possibilities of interface problems from the very start.