Dev. Of a smart equipment based on deformation sensors for automatic correction of thermal errors in machine tools

This project will develop a smart correction method for the purpose of zero-defect manufacturing that minimizes the thermally induced errors automatically during production. The method is based on innovative sensors that can detect structural deformations induced by all existing thermal effects.

The main goal of this multidisciplinary project SMARTEMP is to develop a smart correction method for the purpose of zero-defect manufacturing. The most of the geometrical workpiece errors can be traced back to thermal issues in machine tools (see reference in Chapter 2.2.1), hence the focus of the method on automatically correcting the thermally induced dislocation of the Tool Center Point (TCP) during the production process is expected to have a major impact towards the goal of zero-defects in European manufacturing. The correction method is based on displacement transducers, which measure the elongation of rods made of Carbon Fiber Reinforced Plastic (CFRP). Since these rods have an almost neutral thermal expansion coefficient, the measurement is only negligibly influenced by the thermal growth of the CFRP rod. By mounting such a rod on a machine tool component surface, it is hence possible to measure the thermally induced structural deformation of the machine tool component (e.g. the headstock, the portal beam, the machine tool frame, etc.). The advantage of this method is that the direct measurement of the structural deformation includes information for all thermal influences on the machine tool component where the sensors are mounted. All heat transfer mechanisms (radiation, convection and conduction) and all heat sources and heat sinks inside (friction in axes slides, heat generation in axes drives and ball screws, heat generation from the cutting process, as well as from cooling fluids, chips and lubricants) and outside (environmental temperature short- and long-term fluctuation, air humidity and air velocity fluctuation) the machine tool component have a cumulative effect on the machine tool component´s deformation. Hence, by measuring the global effect resulting from all sources, it is possible to detect the machine tool component´s deformation state with high precision. In order to exploit this advantage, the method also includes the automation technology necessary to correct the TCP-dislocation parallel to the production process as well as to provide the machine tool user and the machine tool manufacturer with transparent information about the thermal behavior of the machine tool during production. Both hardware (embedded computer and data gateways to and from the machine´s numerical control and the factory´s cloud network) and software (model-based calculation of the TCP-dislocation with the input from the sensor data, middleware for the data protocol interoperability and communication between the used proprietary systems, remote monitoring). In order to ensure a secure data and knowledge exchange between the stakeholders of the method (method developer, machine tool builder, machine tool user, numerical control builder), a license-based security provisioning framework will be developed and tested in practice. Novel business models and protection tools will be investigated to ensure a profitable exploitation from all involving parties. Since the model-based calculation include knowledge from the developer, they have to be secured. Since the sensor data include information about the machine state and the method performance, both the developer and the machine tool builder should have access to them. The successful achievement of this goal will involve a strong co-operation among the SMARTEMP consortium partners so as to accomplish the following Work Packages (WP): - WP 1: To define the optimal configuration for the deformation sensors, which ensures the highest possible information content with the lowest possible installation effort. This decision depends on the transient thermal behavior of the demonstrator machine, as well as on the installation space restrictions of its design. This WP will be led by IBARMIA. - WP 2: To develop a computationally efficient, model-based calculation software that translates the sensor data into appropriate correction values of the TCP-dislocation. The development of this software includes also functions that ensure the data interoperability across the data exchange paths. This WP will be led by Fraunhofer IPT. - WP 3: To develop a secure and profitable framework of data and knowledge exchange among the different stakeholders of the manufacturing value chain as well as among all proprietary systems used along the automation infrastructure of the demonstrator machine tool, as described above. This WP will be led by WIBU. - WP 4: To retrofit the demonstrator machine tool with the smart equipment necessary to implement the SMARTEMP method, covering hardware and software described above. This WP will be led by Fraunhofer IPT. - WP 5: To evaluate and quantify the practical advantages resulting from the SMARTEMP method in terms of saving energy, improvement in positioning accuracy and increasing productivity. The method will be demonstrated according to ISO 230-3 norms as well as under real machining conditions. 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Project ID: 
12 249
Start date: 
Project Duration: 
Project costs: 
930 000.00€
Technological Area: 
Machine Tools technology
Market Area: 

Raising the productivity and competitiveness of European businesses through technology. Boosting national economies on the international market, and strengthening the basis for sustainable prosperity and employment.