High-speed clamping system for precise and flexible machining of CNC working centres.
Key words: clamping system, Process chain, CNC
Despite the fact that many different types of clamping systems are on the market, most of them are designed for special fields of application, e.g. the production of electrodes which are used for an eroding process. When used with milling machines or eroding machines in order to work on work pieces, these systems can only be partially applied.
But only a perfect symbiosis between the machine, the tools and a universal work piece clamping system can ensure economical use of a high-performance machining centre for the flexible production of parts (see figure 1).
[FIGURE 1 OMITTED]
Today, work pieces are usually fixed on a vice. That's why the parts do not have a clearly defined position, which is necessary at the beginning of the processing step. Therefore, they have to be aligned with the help of a dial gauge. This is a very time-consuming procedure. The vice also has to be brought into an exact position (see figure 2).
[FIGURE 2 OMITTED]
2. THE SPEED CLAMPING SYSTEM
2.1 Structure of the high-speed clamping system
The clamping system consists of the items listed below (see figure 3):
* base plate with co-ordinated hole pattern
* basic block
* clamping plates
* cone screws
* shoulder screws
* load hooks
The hole pattern is coordinated with the construction units which are manufactured. The base plate is fixed and fastened on the machine table only once. The construction units are centred and strained on a base plate with the help of shoulder screws. Thus the construction unit is brought into a clearly defined position.
The basic block is necessary to achieve a given working height during various procedures, e.g. to position a mill tool at an angle of 90[degrees]. With the help of load hooks which can be screwed into the base plates, an overhead gantry can transport base plates with heavy construction units from one machine to another.
Work pieces which are larger than the clamping plates can be fixed by means of cone screws. The cone screws, which have a fit at the shank, are screwed into the intermediate plate. Large and heavy construction units, which have a mating hole as a complement, can be placed on the base plate by the cone and are subsequently centred automatically. Time-consuming aligning with large work pieces is thus no longer necessary.
[FIGURE 3 OMITTED]
2.2. Use of the clamping system
There are clamping plates of different sizes which are modular (see figure 4). This means that you can simply fix different sizes of work pieces on the plates. They have a hole pattern with hardened sockets. The hole pattern is suited to all construction units of a certain size which can be fixed with it. The hardened sockets guarantee accuracy over a longer period. Should these sockets be damaged by inappropriate treatment, they can be replaced. It is thus possible to mount and reproducibly clamp either differing or identical work pieces. The clamping positions can be stored and retrieved as necessary. This, in turn, permits fast and simple conversion for different work pieces improves the flexibility and ensures high availability of the machining centre. The centre can also be operated in several shifts without major operating costs.
[FIGURE 4 OMITTED]
After a suitable clamping plate has been chosen for the respective work piece and has been taken from the system shelf it is a simple step to centre and strain the part on the clamping plate with the help of shoulder screws (see figure 5).
[FIGURE 5 OMITTED]
The CAD-system first determines the position of the construction unit. The NC system has already defined the point of origin. Aligning with a dial gauge is no longer necessary. The construction units can now be worked on by the machine. The NC programme can also be interrupted and work can be continued where it stopped. This is made possible by the machining axis system which also offers the possibility to finish off a work piece without the necessity to fix it again. The part remains on the clamping plate until the process chain is finished. The clamping plate can be fixed on all machines which use this system (see figure 6).
[FIGURE 6 OMITTED]
Fixing, as described above, is possible while the CNC machine is working. Thus idle times of the machines can be kept to a minimum. This ensures a high efficiency of the machine and increase of the machine running times. Furthermore, it enables the worker to save time (up to 80%) and guarantees greater flexibility by faster changing of the parts as well as higher accuracy and error reduction.
A clamping system which is ideally suited to the requirements of the manufacturing process and which uses an intelligent machine axis system offers many advantages. This system does not just enable us to save time but also benefits the company financially.
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|Title Annotation:||computer numerical control|
|Author:||Gabor, J.; Gansauge, L.; Badjgholi, F.|
|Publication:||Annals of DAAAM & Proceedings|
|Article Type:||Technical report|
|Date:||Jan 1, 2005|
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