IoT-capable hydraulic power unit ensures efficient production
With the newly developed, intelligent CytroBox unit, Rexroth combines the benefits of hydraulics with low energy consumption and software-based functions. The integrated CytroConnect IoT service ensures higher availability and avoids unplanned downtimes. With this IoT service, operators can monitor operating statuses and plan maintenance in a cost-effective manner. As a result, fluid technology has taken a further step towards the factory of the future.
The digitalization of mechanical and plant engineering means more than decentralized intelligence, integrated sensors and connectivity. This applies to hydraulics too. With its power density and immunity to impacts and vibrations, hydraulics plays a central role as an important drive technology in Industry 4.0 too. The compact CytroBox unit is revolutionizing hydraulic pressure supply. CytroBox is a modular hydraulic power unit for the medium performance range from 7.5 kW to 30 kW. It comprises optimally tailored, impressively compact components. Compared to previous units, considerable amounts of space can be saved.
75% less oil
One of CytroBox’s unique selling points is it compactness. This is possible because the hydraulic power unit can be integrated into a factory like a control cabinet, i.e. upright. The tank no longer supports all other components – Rexroth developed a special supporting structure for this purpose. In addition, a degassing flow-optimized tank is used. On the basis of extensive CFD simulations, the developers improved the tank geometry so skillfully that the new unit needs only a quarter of the oil required by classic designs: instead of 600 liters, 150 liters are now enough – with at least the same service life. The drive unit – a component which usually takes up a large amount of space in hydraulic power units – is equally compact. The asynchronous servo motor has been replaced by a synchronous servo motor. This is the most efficient motor design, producing the same torque even though it is 80 to 90% smaller. The manifold too was redesigned: thanks to 3D printed sand cores, the block including the internal flow geometry is now cast. As a result of this flow-optimized inner structure, less material and space are required. Thanks to all these measures, the CytroBox has a footprint of just 0.5 square meters instead of one and a half to two square meters. This represents a saving of up to 75%. On top of this, there are energy savings of up to 80% as well as a 10 dB(A) reduction in noise emissions. As a result, noise emissions are lower than 75 dB(A).
Connected for the factory of the future
In the CytroBox, machine manufacturers will find a ready-configured drive controller with numerous integrated functions. Various sensors provide information on the current filter, oil or drive status. The collected sensor data are bundled via IO-LinkMaster and pre-processed by the drive controller so that they can be integrated flexibly into modern machine designs. This means that the CytroBox is IoT-ready.
With the CytroConnect digital service, operators have all information regarding the CytroBox at their fingertips at all times – whether it be information regarding the standardized visualization of the component and operating status or chargeable IoT services such as forthcoming maintenance work and predictive maintenance analyses using Rexroth’s Online Diagnostics Network (ODiN).
The data collected are transferred to the browser-based CytroConnect Monitor web dashboard via Multi-Ethernet or 4G-LTE. As a result, operators can be kept up to date regarding the current operating status and key status indicators on any end device (tablet, smartphone, PC). This plug and play service is free of charge and can be used without additional installation work. CytroConnect is implemented in the CytroBox as standard.
Greater availability thanks to additional analysis functions
In addition to the CytroBox’s automatic status monitoring, maintenance personnel and maintenance managers can add extra solutions for various applications as add-ons. These pay-per-use payment models include additional IoT analysis tools and can be subscribed to on a monthly basis.
For optimizing maintenance processes, the CytroConnect Maintain module offers access to historical sensor data as well as messages if maintenance is required or in the event of critical operating statuses. Pre-defined and custom rules allow customers to improve their maintenance strategy on an ongoing basis. Customers benefit from scalable software solutions from the Bosch IoT portfolio such as the Nexeed Production Performance Manager and the integrated know-how of the Rexroth domain specialists. The Nexeed Production Performance Manager is a condition monitoring software solution for systematic production optimization.
With CytroConnect Maintain, data concerning the most important components for reliability and operating life (the hydraulic oil and the drive unit) are assessed. Comprehensive insights into the correlation between the speed of the servo motor and the flow allow the monitoring of system leakage, while correlations between motor data and the operating pressure allow conclusions regarding drive behavior. The leakage sensor, temperature and level sensor, particle sensor, water sensor and oxygen sensor are additional data sources which can be used to make a status diagnosis.
Planning predictive maintenance efficiently
A further add-on, CytroConnect Predict, uses the machine learning algorithms of the Rexroth Online Diagnostics Network (ODiN) for a predictive analysis of the system. With this IoT service, the power curves for a wide range of components are recorded for data analysis purposes. In the event of deviations, the system automatically calculates the expected remaining operating life of the relevant component and informs the operator immediately via a push message. As a result, predictive maintenance application cases can be taken into account predictively in the operator’s maintenance plans, thus ensuring maximum availability. Conclusion
This new form of hydraulics is energy-efficient, quiet, space-saving and intelligent. With the integrated CytroConnect IoT service, the CytroBox offers anything from transparent, efficient machine monitoring to intelligent predictive maintenance measures. Thanks to the CytroBox, fluid technology is now one step closer to the factory of the future.
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Time and cost savings through standardization and proven designs
Faster, simpler, more productive and cost-effective: Rexroth’s new modular system called ABMAXX speeds up the engineering and commissioning of large hydraulic power units in projects designed to modernize existing systems or construct new ones. The hydraulics specialists are able to create a quote complete with a hydraulic circuit diagram, a parts list, a 3D model and dimensions all within a maximum of five working days. As such, system manufacturers and end users can reduce engineering lead times alone by 80 %. The pre-configured ABMAXX modules are composed of highly available standard components. The modular approach reduces costs by up to 35 % and increases operational availability.
When constructing new or modernizing existing steelworks and rolling mills, large-scale presses and test systems or the central media supply of factories, hydraulics is and will continue to be the key drive technology both now and in the future on account of its high power density, robustness and durability. Thanks to the wide range of components available, there is plenty of scope for designing tailored solutions. In the past, system manufacturers and major end users defined their own standards which they implemented with their own resources in development. In light of ever increasing cost pressure and a global shortage of qualified specialists, these days they are increasingly scrutinizing that approach. Their main goal is to achieve pressure and quantity as cost-effectively as possible.
This is where Bosch Rexroth’s modular system ABMAXX comes in. The company is the first hydraulics manufacturer to come up with a modular solution with which system manufacturers and end users can significantly reduce the complexity of engineering large power units for 24/7 operations. On the one hand, it enables them to take advantage of all the economic benefits of cross-manufacturer standardization yet, on the other hand, the modular design provides ample opportunity for coming up with application-specific solutions.
Three pressure ratings and five modules
The concept initially covers tank sizes ranging from 2,000 to 12,500 l. With its three pressure ratings, namely 160, 210 and 315 bar, the concept satisfies the trend for higher operating pressures, thus ensuring it will be fit for the future. Achievable flows currently range from 345 l/min to 2,160 l/min. These basic conditions meet the typical requirements of numerous large plants.
In order to transform the benefits of standardization into shorter project lead times, Rexroth has defined five modules: tank, pump block, circulation unit, cooling and filter unit, and safety controls. Each module is based on proven constructions with a tried-and-tested design. As such, Rexroth is able to considerably reduce the risk of initial errors in the construction.
Simplify the design - Up to 80 % time savings in engineering: Offer in a maximum of five working days
The benefits of standardization and modularization are clear to see at the project planning phase. These days, depending on the level of complexity involved, planning customized individual power units in line with relevant company standards can take four to eight weeks. Rexroth is able to whittle this phase down to a maximum of five working days with its modular system ABMAXX. Rexroth is able to provide 3D models complete with dimensions and parts lists as well as the hydraulic circuit diagram and a quote all based on the customer’s specifications within just one week. This shortens the engineering effort by up to 80 %. This enables designers to save valuable time, which they can use on their projects, and enables system manufacturers to shorten the quote phase.
Streamline the installation - Up to 35 % lower costs through standardization
In comparison to using completely newly designed large power units each time, system manufacturers and end users achieve between up to 35 % direct cost savings on account of modularization and standardization. Internal costs are also reduced thanks to shorter project lead times and shorter time to market for system manufacturers. End users can also use individual ABMAXX modules such as the pump block in order to modernize their systems step by step and improve energy efficiency, for example. The wide range of Sytronix variable-speed pump drives is also able to unlock considerable potential here for reducing power consumption based on demand. Tried-and-tested safety controls help designers to comply with corresponding safety regulations and documentation requirements in line with standards. The choice of standard components also reduces delivery times and cuts costs.
Through its global production network, Rexroth also ensures high local added value and a quick response to customer requirements. Competence centers for power units construction in Europe, Asia and the Americas cover all major regions with short distances.
Maximize the productivity - Latest technology for maximum efficiency
At ABMAXX, Rexroth uses latest technology for all components and the hydraulic design. The components set standards in terms of dynamics and life time. Proven design principles increase productivity through high repeat accuracy and energy efficiency. The wide range of variable-speed pump drives in the Sytronix family opens up considerable potential for reducing energy consumption as required. This reduces life cycle costs sustainably.
With the three pressure stages up to 315 bar, the concept meets the current state of the art, but already reflects the trend towards higher working pressures.
Minimize the downtime - User and maintenance friendliness increases availability
The modules have been designed so as to ensure optimum component accessibility. What's more, standardization reduces the required maintenance and servicing over the entire life cycle as the standard components used are available at short notice and will be part of the product range over the long term. The modules are composed of highly available Rexroth standard components. They are designed to deal with harsh environmental conditions including humidity, heat, dust, contamination and vibration.
The components are designed to work equally well with mineral oil as with water-based media such as (HFC) and synthetic water-free fluids (HFD). As such, Rexroth’s axial piston pumps achieve the same service life regardless of the media involved.
The pump block and the circulation unit are fundamentally equipped with stand-by units in order to guarantee maximum availability. The pump block and the circulation unit are always equipped with stand-by units for uninterrupted 24/7 operation.
First power units already in use
Bosch Rexroth has already made several ABMAXX as complete power units and individual modules for modernization projects. System manufacturers for metallurgical plants and operators of steelworks and rolling mills are among the first users. However, potential applications exist across all sectors of industry as well as in large-scale projects.
Bosch Rexroth will be presenting the large modular HPU ABMAXX for the first time at METEC 2019 from June 25h to 29th in Hall 5, Booth D30. Take the opportunity and talk to our experts!
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Performance-enhanced valve technology and system solutions for die casting machines
With newly-developed control valves for the shot, which is the injection process in die casting, Rexroth has set a new standard in terms of dynamics, even at high volume flows. Based on these valves, industry specialists at Rexroth have developed patented system solutions. With little engineering effort, these system solutions increase the quality, productivity and energy efficiency of die casting machines.
Die casting machines are extremely efficient when it comes to producing components from a wide variety of non-ferrous metals and alloys. The world market for components manufactured using this process reached a volume of approximately $ 63 billion in 2017. Experts expect the market to grow to around $ 94 billion by 2023. This is equivalent to an annual growth of nearly 7 percent.
An important customer for die casting components is the automotive industry with its ever-increasing quality requirements. It is therefore a pioneer for other industries. At the same time, the trend is towards ever-more complex geometries with increasing demands on the accuracy, dynamics and reproducibility of all motion sequences during the shot. This is the most important lever for reproducible, zero-defect quality and, therefore, user productivity.
In addition, end users also expect a significant increase in energy efficiency for new machines. The automotive industry, in particular, is striving to reduce the ecological footprint of its manufacturing processes. Further requirements have to do with achieving the smallest possible footprint of the machines and, in the future, getting ready for Industry 4.0.
Distinguishing feature: "The shot"
The quality of the shot is a decisive differentiating feature in die casting machines and depends on the dynamics and control quality of the high-response cartridge valves.
For the injection process, hydraulics is the drive technology of choice. It offers the highest power density, and is robust and durable. Due to its de-centralised design, engineers have a high degree of freedom to optimize the space. New patented hydraulic valves and system solutions from Rexroth extend these benefits through greater dynamics, better controllability and lower energy consumption throughout the injection process.
The injection process itself consists of three phases:
Phase 1: Starting
Jolt-free starting is necessary so that the molten metal does not mix with the skin on the molten metal and with the air. At a controlled low speed, the air is pressed in a controlled manner out of the chamber. In this phase, a good resolution at low speeds is particularly crucial.
Phase 2: The shot
The "shot" requires very high acceleration values, and high reproducible speeds so that even complex and filigree components can be manufactured before the liquid melt solidifies.
Phase 3: Pressurisation
During the final phase when the molten metal is pressed into the mould, it is very important that the pressure is built up rapidly. To date, solutions that include pressure intensifiers are commonplace in the market. New hydraulic components and system solutions from Rexroth cut the pressure build-up times in half, making it possible to produce more complex and larger die-cast parts.
The dynamics and the reproducibility across all three phases have a direct impact on productivity: thanks to a lower error rate and a higher process reliability for components with complex geometry.
System solutions: Modular and scalable
Rexroth has developed patented system solutions for the shot in die casting machines, with which manufacturers can better control the process and save additional energy. These systems are based on new control valves that are improved in terms of dynamics and rated flow, a special non-high pressure check valve, and various storage arrangements. The system solutions significantly reduce the development effort of the manufacturers, because all components are matched in terms of performance and functionality.
All system solutions work with a regenerative circuit in phase 1. Here, a small, dynamic 2-way control valve of the latest generation is used. It controls the smooth start and generates the specified speed in high resolution. Thanks to the regenerative circuit, around 50 percent less energy is consumed during phase 1. In addition, it reduces possible cavitations in the system and thus wear on the valve piston, valve housing and control block. In addition, this prolongs the service life of the hydraulic medium.
For the "shot" in phase 2, the newly-developed 2-way high-response cartridge valve is opened with a jump in the outlet of the injection cylinder and the cylinder is accelerated to the desired injection speed within a few milliseconds.
The fast transition from shot to pressurisation is enabled by the special check valve from Rexroth in about 10ms, thus allowing for an extremely fast pressure build-up.
To regulate the pressurisation, a 3-way control valve is often used nowadays. The solutions from Rexroth rely on 2-way functionalities that are intelligently interconnected. Here, the higher volume flow of the 2-way control valve is used instead of a 3-way control valve. Often times, the valve can be reduced by one nominal size for the same volume flow. This lowers costs while increasing the dynamics.
In the most dynamic system solution of all, a high-pressure accumulator replaces the usual intensifier. The time required to accelerate the pressure intensifier is eliminated, and the nominal size of the 2-way control valve becomes smaller, since only about one third to half of the oil is needed to build up the pressure. This results in very short pressure build-up times and energy savings. In another solution, it's common for manufacturers to use a pressure intensifier. By reducing the size of the control valves for phase 1 and phase 3, the system becomes cheaper and more dynamic. The special check valve also shortens the pressure build-up time.
All of these solutions use energy-efficient variable-speed pump drives from the Sytronix family. For the three phases of the shot m anufacturers can also use the Motion Control HMC .
Components optimised for die casting machines
New generation of highly dynamic control valves
For a long time, the high-response cartridge valves used in the shot were considered to be developed to the max. But with the new generation of 2 WRCE - 4X, Rexroth has set a new state-of-the-art standard. Larger volume flows make it possible for manufacturers to use smaller, more dynamic valves with the same machine size. This lays the foundation for significant process improvements.
The pilot-operated valves with integrated digital control electronics communicate with the higher-level machine control via a multi-Ethernet interface for all common, real-time Ethernet protocols. This enables machine manufacturers to tap all the benefits of fieldbus technology for start-up, operation and diagnostics. The control valves also provide improved speed and pressure control in otherwise unmodified hydraulic systems.
The special check valve
Depending on the nominal size, the special check valves in the LC2A family have closing times of 10 - 20 ms, which is faster than the market standard. Thanks to the active closing, the process becomes more repeatable than with conventional check valves.
Variable-speed pump drives
In all system solutions, variable-speed pump drives reduce the speeds at partial load in line with demand . They therefore achieve energy savings of up to 80 percent depending on the cycle, and lower the average noise emissions by up to 20 dB(A). Rexroth has harmonised numerous drive-motor-pump combinations in the Sytronix family. Two versions are especially suited to die casting machines:
Sytronix DFEn uses p/Q control systems to convert the installed engine power into fast travel or powerful pressurisation as needed. Here the variable displacement pump assumes a gear function.
With Sytronix SvP, synchronous servo motors with permanent magnet and servo control ensure maximum dynamic performance and control accuracy. They cover the widest range of functionalities: from pressure regulation to release pressure volume flow control to release position and power control.
All Sytronix versions integrate into a wide variety of automation architectures via a multi-Ethernet interface for all common, real-time Ethernet protocols.
Motion Control HMC
The control algorithms of the Motion Control HMC, which are specially tailored to the physical conditions of fluid technology, enable unprecedented process quality during the shot. Manufacturers can also create their own functions using the standardised IEC 61131-3 languages.
With multi-Ethernet and multi-encoder interfaces, the Motion Controls integrate themselves into a wide variety of control concepts and close the control loop in a decentralised manner. The HMC supports communication via the automation bus S ercos, EtherNet/IP, ProfiNet, EtherCAT, PROFIBUS, as well as CANopen. The motion control system networks the hydraulics with higher-level controls and systems leading up to Industry 4.0.
The HFC hydraulic media frequently used in die casting machines present particular challenges for high-pressure pumps. On the other hand, the A4 high-pressure pumps also achieve the same long service life and high speeds with HFC media as in mineral oil operation and allow pressures of up to 450 bar.
Injection cylinder with integrated position sensor
Rexroth offers injection cylinders with integrated SSI absolute position sensor systems. They measure more accurately than external displacement measuring systems and are immune to environmental pollution. After a machine standstill, the absolute position encoder detects the exact cylinder position without referencing.
Rexroth's performance-enhanced valves and intelligent, modular system solutions significantly increase the productivity of die casting machines. They improve the dynamics and the reproducibility of the movements. As such, they create the prerequisite for a high hit rate during the shot - also for components with complex geometry. At the same time, they reduce system costs through smaller valves and improve energy efficiency over the entire life cycle.
Bosch Rexroth will be presenting the new components and system solutions for the first time at the GIFA 2019 Hall 11 Booth G55. Seize the opportunity and talk to our industry specialists.
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Most power plant operators do not realize what they are risking if they allow seal wear in hydraulic actuators to simply take its course. In this practical guide you will find out why this aspect is so important and how to cost-effectively prevent damage and production downtime with predictive planning.
In order for gas and steam turbines to generate electricity with the right output and rotational speed, the supply of media must be precisely controlled. Hydraulic actuators ensure exact control of the valves. In the event of a malfunction, they also carry out an important safety function by mechanically disrupting the flow of medium and redirecting it. In order to ensure this in the long term, it is essential that the hydraulic actuators for gas and steam turbines are inspected and maintained at regular intervals in accordance with the relevant legal regulations and manufacturer's recommendations. The reason: each hydraulic actuator – no matter how high-quality it is – exhibits wear due to operational reasons. The wear starts on the seals and, in the absence of maintenance, may extend to other components. Anyone who disregards this fact, and waits until an obvious failure occurs, risks high repair costs and long waiting periods until unrestricted production can be resumed.
Imminent loss of the SIL capability
If the specifications from the operating instructions and the safety manual are not complied with – maintenance requirements and proof-test intervals, for example – or if the actuators are not properly used, under certain circumstances the drive loses its SIL conformity and thus its suitability for safety-related applications. Improper usage includes the use of dirty or contaminated hydraulic oil. This can lead to failure of the solenoid valves and cartridge valves, as well as to increased wear on the piston rod seal and the piston rod. In addition, unsuitable placement in the escaping steam can cause damage due to overheating (cf. 1.3), which can subsequently result in strong corrosion on safety-related components – such as magnetic and cartridge valves, piston rod, and spring assembly. Last but not least, a lack of regulation or control poses a risk to the SIL capability, because inadmissible oscillations could cause significant wear in short time.
1.1 Ongoing seal wear
In particular, if the piston and rod seals are not replaced according to the schedule for the actuator – at the latest after six years – the wear will lead to functional impairments. First, leakage occurs; later, there is damage to the piston and the piston housing. Depending on the circumstances, this leads directly to failure. On the one hand, the wear ensues regardless of the product quality due to the aging process of the sealing material, which gradually becomes brittle and porous, so that the sealing effect decreases. On the other hand, the frequency of the changes in movement, in combination with the stroke length, plays a role. The strokes are therefore to be determined by the control system so as to ensure that an adequate lubricating film and thus low-wear operation for the seals are ensured. Constant operation in the short-stroke range, on the other hand, leads to increased seal wear and damage to the mating surfaces. Especially in the case of short strokes at high-frequency, the replacement intervals for seals recommended in the maintenance schedule can be significantly reduced. Regular monitoring is essential.
In the case of actuators that only extend to short strokes or remain in one position over a longer period of time – depending on the application, this could be several weeks or months – separated seal particles mostly remain in the chamber, as there is hardly any exchange of the oil. Thus, contamination on the inside of the cylinder builds up and the sealing rings wear down more quickly.
Not recognizable from the outside: The natural aging process makes the seals inside become brittle and porous. Permanent operation in shortstroke range additionally limits the sealing effect.
1.2 Incorrect maintenance or assembly
Apart from the wear, maintenance or assembly errors could also be the cause of permanent damage to the actuators. A common source of error is the alignment to the steam or gas valve. If a valve and piston rod are not properly aligned, lateral forces acting on the coupling place stress on the guide belts. Consequently, the guide belts and the seals wear excessively. A further cause of damage resulting from faulty handling is the filling of the hydraulic system with an incorrect fluid. This can trigger a chemical reaction between the seal and the fluid, which in turn accelerates the process of wear and tear.
1.3 Special risks associated with steam valves
Power plant operators who generate electricity by means of steam should also observe the leak-tightness of the steam valves in the direction of the cylinder. If the more than 500 ºC hot medium flows long enough over the outer coating of the actuator, the coating can “burn off” there so that the surface becomes corroded. Apart from this obvious damage, the spring assembly inside the cylinder can also be damaged, which, in the event of a malfunction, subjects the valve purely mechanically to up to 400 kN force in the locked position.
At the interface to the armature – the coupling – the ambient temperature must not exceed 200 °C. As a result of the effects of excessive heat, the existing anticorrosive coating – consisting of a layer of wax on the Belleville spring washer system – can be damaged. If a rusty spring breaks, the actuator loses its safety function. In this case, the component requires an immediate overhaul in a manufacturer’s certified service center.
In addition, uncontrolled steam discharge can damage the actuator due to overheating of the hydraulic fluid, because the fluid temperature must not exceed 70 ºC in circulation. If the system can not compensate for the influx of heat, the hydraulic oil will be “burnt”. This means that it becomes viscous and sticky. The seal wear increases, valves and other components lose their freedom of movement and function.
Safety-relevant component: The spring assembly inside the cylinder brings the valve into the safety position purely mechanically in the event of a malfunction. If it breaks due to corrosion, the actuator loses its safety function.
2 Consequences of inadequate maintenance
2.1 Reduced control quality
Even before the seals lose their originally intended function through continued wear, increasing internal or external leakage leads to energy losses. The accompanying temperature rise in turn promotes wear and tear in other areas of the hydraulic system. Another consequence of the increased leakage is diminished control quality. Therefore, under certain circumstances, the system would no longer be able to adjust the required performance of the turbine with sufficient accuracy.
2.2 Mechanical damage (worst case)
If the damage of the seal system has deteriorated to such an extent that it leads to mechanical contact between the piston rod and cylinder housing, the main components suffer permanent damage. Due to the leakage that occurs, the actuator can no longer properly perform its regulatory function. Although this is not safety-relevant with the Belleville spring washer system intact, the damage is however much greater. Because in comparison to preventive seal replacement, an extraordinary repair is now due which, in comparison with a normal overhaul, is significantly more complicated and more expensive. The reason: the main components of the actuator, such as the cylinder housing and piston, are generally not stockable items for the manufacturer due to the large variance. Some parts must even be cast and then machined. In the worst case, this could take weeks or months. If the waiting period occurs during the high season, operators must possibly accept painful constraints to production.
3 Recommendations for practical use
3.1 Preventing the worst-case scenario
Anyone who wishes to avoid the worst-case scenario in a cost-efficient manner, should not only comply with the maintenance rules and instructions, but also schedule major inspections in a timely manner. …
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