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The machine tool sector remains in the spotlight since in the near future, the automotive and machine tool industries, in particular, will be subject to strict CO2 emission reduction policies

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Power Presses Adopting energy efficiency

May 16, 2017

The article discusses the concept of Green Press Technology, that will offer tools and market solutions required to address strict energy efficiency policies, which will appear in the short to medium term; the need to increase competitiveness and the need to tackle the objective of reducing energy-associated costs.

One of the biggest challenges that today’s society will have to tackle is the need to mitigate three energy-related realities— excessive energy dependency of industrialised nations, depletion of the principal energy sources, and high levels of contamination. Given the scale and urgency of these realities, failing to address this challenge in the short to medium term would be folly, since, as the energy consumption dependency and growth indices show, an increasing amount of resources will need to be invested in scientific production, as well as energy efficiency policies, to guarantee a competitiveness which has waned in recent years.

If we factor in that over the coming years, the global energy demand will increase, raising awareness on the importance of high energy consumption in industrial facilities which seem to be unavoidable. Reducing the environmental impact will be a constant strategic objective. In recent years, corporate energy costs have increased significantly, entailing a grave handicap as regards to improving competitiveness. This has resulted in the urgent need to reduce energy costs, encouraging policies conducive to favouring increased energy efficiency. It is also worth mentioning that the machine tool sector remains in the spotlight since in the near future, the automotive and machine tool industries, in particular, will be subject to strict CO2 emission reduction policies.

Developments in moulding systems

Servo-mechanical cushion: One of the main areas for improvement in the reduction of energy consumption and energy regeneration is the cushion. Considering that servo presses are increasingly prominent in the international market, it was decided to develop a new concept of cushion. This new concept supersedes the hydraulic press driven by electric servo-motors, and using a rack and pinion mechanism, transforms the electrical energy from the servo motor into the mechanical power, required for the die stamping process. This solution enables us to create an ideal architecture in the main drive of presses with servo technology. Control is by means of the SIMOTION platform, and is currently in the final stage of development.

Hydraulic ECO-cushion: Taking the standard hydraulic cushion as a reference, the company has two fully designed solutions for reducing energy consumption through energy savings. In the first of these, variable flow motor pumps help to reduce consumption, thanks to their own self-adjusting control, making it possible to reduce the necessary flow, adapting it to the real needs of each cycle. The second, the high-low pressure concept, is a solution devised in the current moulding process; the facility is sized in proportion to the needs of the moulding process. Lastly, a final solution adds to the idea of high-low pressure, referred to above, a servo-pump system to regenerate most of the energy consumed during the moulding process, returning the energy consumed in oil rolling to the buffers, or in a controlled manner to the grid.

Solution 1: A variable-flow motor-pump

This solution can be installed easily into existing hydraulic units. The current motor-pumps would be replaced by variable-flow motor-pumps. This system allows flow control to be incorporated into the system, totally autonomously and without the need to install any additional software. This simple modification allows a facility to be fitted with integrated control, reducing energy consumption by over 30%.

Solution 2: High and low pressure concept

With this solution, two differentiate phases can be distinguished in the pressing process. Two different circuits are designed to perform two characteristic functions of a hydraulic cushion. On one hand, a high-pressure, low-flow system is installed to pre-accelerate the cushion when so required. On the other hand, a low-pressure but high-flow system is designed, with the aim of performing the pick-up and following functions, etc, and thus guarantee the speeds required by the facility. The high and low pressure concept reduces the installed capacity by 40%, resulting directly in a significant energy saving. The amortisation period for this solution is under one year and the savings in energy costs are estimated to be five times of those obtained with solution 1.

Solution 3: High and low pressure + energy regeneration system concept

The two solutions analysed above offer great saving potential—on one hand, optimising the needs of the cycle and on the other, reducing the installed power to adapt it to the real needs of other cycle. Nonetheless, scientific output in recent years has not focused solely on the goal of developing energy-saving technologies, rather the evolution has been accompanied by energy regeneration technologies. Incorporating the latter technology into Solution 2 allows customers to achieve a high-performance facility in terms of energy efficiency.

Presses with servo technology

Servo press configurator: The solution enables our customers to analyse different configurations for their servo press, configure velocities and strokes, and verify that the forces required are available for the job, in an easy and simple way, thus, obtaining optimised configurations and offering the best solutions in line with the customer’s needs.

In the example of optimisation with the configurer, it can be seen how a conventional press with an 800 mm stroke and a moulding speed of 15 m/min, can be replaced by a servo press, with a significant increase in cadence, maintaining the contact speed during the moulding and providing time for any other transfer processes that may be required. That is, we use the capabilities of servo technology to be able to vary the speed throughout the cycle, clearly bringing forward the end of the cycle in comparison with the conventional cycle. It is important to mention that, in comparison to a conventional press, servo technology offers improved energy performance: a reduction of up to 20% in energy consumption is estimated, depending on the facility’s operating mode. While in continuous mode, the improvement is not significant, in stand-by and start/stop modes, the improvement is notable.

Syncro 3D: This entire optimisation process is costly and has a bearing on the machine’s availability and the possibility of implementing improvements in the cycle, in order to obtain greater cadences. This is why Fagor Arrasate has developed software aimed at providing support for customers’ process engineering, in order to offer a resource with which to bring forward all this optimisation to the completion of the project. This software named Syncro 3D, makes it possible to assess the feasibility of any cycle performed with a servo press, as well as to check the possible interferences that may arise during the transfer of the piece.

Reduction of CO2 emissions with GPT technologies

All of these solutions for moulding systems focused on increasing energy solutions result in a reduction of CO2 emissions in the industry through the reduced use and regeneration of energy, as well as through the optimisation of the production process. Also, innovation must be conceived as the main factor in the development of new solutions in the deformation sector. Thus, the concept of GPT (Green Press Technology) will offer the tools and market solutions required to address the strict energy efficiency policies that will appear in the short to medium term, the need to increase competitiveness, and the need to tackle the objective of reducing energy-associated costs, since these will undoubtedly be the priorities that will have a bearing on the market in the not-to-distant future.

Image Gallery

  • Drawing cushion development

    Image: Fagor Arrasate

  • Servo press technology

    Image: Fagor Arrasate

  • Example of optimisation with the configurer

    Image: Fagor Arrasate

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