Finishing cells for large series
With this kind of plant the design of the overall configuration is tailored to one type of product, the most important feature being the functionality of the cell with its different operations, taking the cycle time into account. The means used are designed with little flexibility, even though there is no exclusive concentration on one single product type.
This type of plant also allows for a variety of different combinations. There may, for instance, be the following architectures:
- inspection line with component identification and palletising,
- coarse deburring, de-coring, sawing and fine deburring,
- pre-sawing and de-coring,
- trimming and component inspection,
- trimming and shot-blasting as well as
- component identification, trimming and additional finishing by sawing or milling.
The list of possibilities is a very long one and generally tailored to the customer’s process requirements.
Figure 5: Flexible machining cell for aluminium intake manifolds, their main configuration consisting of:
1 “Arcade” trim press with twin shuttle (1),
2 industrial robots (2),
2 sawing and milling stations (3),
4 air/air leak test stations (4),
3 discharge belts of the test stations from the cell and a turntable for visual inspection of the finished parts (5), and
1 discharge belt for returns (6).
Combination of trimming and shot-blasting
This plant shows how the products of the individual companies within the group can be integrated into the end customer’s systems easily and without any additional expenditure. The co-operation of the different product groups provides the advantage that the necessary tests can be carried out in the final configuration and after one-time assembly. Any possibly interfaces, fine tuning and process determinations are integrated into the plant.
Trimming cell for die-cast aluminium engine blocks with integrated shot-blasting machine and removal of abrasives
The plant consists of
- a twin chain conveyor system for engine block feeding (1)
- a linear manipulator (2)
- an industrial robot (3)
- two shuttle trim presses with swing frame (4)
- an shot-blasting machine (here an SPH 3 spinner hanger shot-blasting machine with three chambers) (5)
- an engine-block turning station for the removal of the abrasives, and discharge roller track (6).
Figure 6 shows a view on the trim presses and the linear manipulator. The feeding conveyor is located between the two trim presses, shortening the travel of the linear manipulator within the working range of the robot. Due to the auxiliary cranes and the shuttle the trim tools can be changed within a few minutes and production can be continued. The combination of rapid fasteners for the hydraulic and electric fittings also greatly facilitates a change of tools.
Figure 7 again shows the configuration of the auxiliary cranes. The industrial robot – in this example a foundry robot, type ABB 6600 – feeds a DISA SPH 3 shot-blaster where surface treatment takes place following trimming. After unloading of the shot-blasting the industrial robot places the engine blocks onto the turning station to remove the remaining abrasives.
Twin chain conveyor. From the superposed cooling line the engine blocks are conveyed to the twin chain conveyor together with their gating system. Both possible types of casting are transported at the same time. At the conveyor outlet the blocks are separated and realigned. A recognition system chooses the trim press to be selected for the individual type of component.
Linear manipulator. The linear manipulator is used to allocate the engine blocks to their respective trim press. Electrically driven by servo motors these manipulators have a high speed and accuracy of position necessary to place the components onto the pick-ups of the trim dies. The use of the manipulator releases the industrial robot, which enables the latter to remove the abrasives. Component pick-up by the manipulator is guaranteed by pneumatic grippers. The assembly and connections facilitate a change of parts for a changeover to another series. The gripper itself is designed to a large extent in such a way that it can already handle a large number of different types of parts.
Industrial robot. The industrial robot used is equipped with the same gripper system as the linear manipulator. The robot unloads the trim presses and loads/unloads the shot-blasting machine. The master control station allocates the different runs of the robot. Thus it is the master control that defines the priorities and sends them to the robot. This technology makes the robot interface definite, and it only communicates with one single control. This relief from a multitude of tasks enables the robot to empty the engine blocks from abrasives prior to re-loading.
Figure 6: Inlet conveyor, robot
Figure 7: Shot-blasting machine (DISA, Type SPH3)
Shuttle trim press. The shuttle trim presses used (Figure 8) are equipped with a C-frame. The shape of these machines in connection with the hydraulically driven shuttle has the advantage that the trim dies can be loaded and unloaded from above, without any access problems. The 300 kN presses used here are equipped with a swing-frame system that carries out a 180-degree movement after unloading, removing the burrs that might still remain on the tool dies.
In combination with the swing frame that is air cleaned while tilted, the shuttles provide a degree of cleanliness that guarantees the uptime of the equipment. This technology rules out the possibility that remaining burrs can easily be pressed into the component pick-up, as it happens in many other cases. Moreover, the shuttle greatly facilitates and speeds up the replacement of the trim die. The combination of automatic rapid fasteners for the hydraulic and electric systems makes tool change a matter of just a few minutes.
The tool fastenings can be disconnected without any additional devices; the shuttle moves the entire tool from the cylinder area, where it is removed by crane. Normal replacement time is approximately ten minutes. The tools are designed for one coarse and fine deburring operation in one single cut. Thus the gating systems are removed directly; the further course of the operation includes fine trimming. The maintenance platform and the hydraulic unit that is attached to the machine provide ready access to the main elements of the plant.
Shot-blasting machines. A variety of shot-blasting machines are used depending on the production task and on the material to be machined. Charging modules or robots are used to automate the peripheral functions and increase performance. Multiple-chamber shot-blasting plants facilitate shot-blasting during loading. Thus, the effective shot-blasting time can be prolonged as and when required to achieve a better surface finish. In connection with programmable sequences (turning, swinging, holding), critical areas can be subjected specifically to the blast of abrasives. Fully automatic machines are equipped with component recognition systems through which the blasting parameters are controlled (blasting time, sequence of movements of the components within the blast stream, number of blasting wheels, discharging time). After shot-blasting the residual abrasives are evacuated from the components.
Figure 8: Shuttle trimming press
Low personnel expenses and the high output of finished parts make these plants a finishing concept that considerably reduces the costs for casting finishing per component and furthers production at the classic foundry bases. The concepts described here do not yet include grinding machines or the combined plants for decoring, coarse trimming, fine trimming and saws of the DISA Group that will be the subject of another article.