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New Design for Hydraulic Power Units

Guest contributor:  Andreas Günder, Bosch Rexoth

Optimum power, less installation space: Thanks to new intellectual and design approaches, compact hydraulic power units increase the economic efficiency of machine tools.

Powerful force in a very confined space

In the production world, hydraulics are firmly established. Machine tool manufacturers appreciate hydraulics for their high power density, toughness and modular design. In the lower performance range up to 4 kW, however, there are also some challenges. Since the installation space is often limited, designers and technical purchasers are constantly looking for increasingly compact solutions.

Installation space is valuable

The demand for compact hydraulic drives is not only due to the structurally limited flexibility regarding extensions, modernization measures and refittings but also due to the requirements regarding acquisition costs and assembly times or structural extensions of the working space with given machine dimensions. In addition to the level of integration of the functions, energy efficiency often plays an important role as well. Last but not least, many manufacturers are following the miniaturization trend. If workpieces become increasingly smaller, the moved mass of the machine tool has to be decreased accordingly.

“Installation space eaters” hydraulic power units

To reduce the installation space, solution manufacturers can start mainly with the following components: hydraulic power unit and control cabinet. When considering this split, it becomes evident that compact power units which are also easy to integrate require completely new design approaches to eliminate all features which waste unnecessary space in the performance spectrum up to 4 kW and to ensure that the units are still compatible with many different machine designs.

Highly integrated design approaches

The features of such innovative design concepts according to the EU Eco-Design Directive 2009/125/EC for example include a tank which is optimized for efficient degassing and reduces the oil volume by up to 80 percent. A much more decisive factor for gaining space is, however, that all functions can actually be integrated in one small power unit – from an economic variable-speed drive for demand-based power output to sensor technology with filling level, temperature, pressure and filter contamination sensors to a completely wired frequency converter.

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Compact and ready for Industry 4.0

For the future viability of this approach with regard to Industry 4.0, a data interface is essential as well. Only with permanent condition monitoring can the operating conditions be optimized comfortably and relevant faults be detected early on. With this equipment, the user only has to connect the electric power, the data interface and the hydraulic supply during installation and the hydraulic power unit is ready for operation

New cooling with heatpipe

So-called heatpipes are considered to be a space-saving innovation regarding the cooling of hydraulic power units. Their high-performance passive thermal conduction allows for a further reduction of the frame size. The heatpipes absorb the thermal energy of frequency converter, motor and hydraulic oil and efficiently transfer it to a central heat sink such as e. g. cooling water…
This ensures an intelligently optimized thermal management within the hydraulic power unit and optimally utilizes the cooling power of the cooling water. There is no need for a separate hydraulic circuit for oil cooling. This reduces installation space, noise emissions, energy consumption and possibilities for leakage.

Heatpipe – Functional principle

Basically, a heatpipe consists of air-tightly sealed copper pipes with underpressure. Inside, there is a medium which transfers thermal energy. In the temperature range of hydraulic power units, the medium may be e.g. distilled water. The boiling temperature of the water is significantly reduced by the low pressure within the heatpipe, which means that a boiling or condensation process can already take place at low temperatures.

Functionality: If you dip the heatpipe for example in hot hydraulic oil, the thermal energy at the lower immersed part of the heatpipe is transferred to the water. The water exceeds the boiling point, evaporates and absorbs a large amount of thermal energy with low temperature difference (latent heat). The water steam rises to the upper part of the heat pipe which is cooled by e. g. a cooling element. Here, the water steam condensates and gives off the thermal energy to the cooling water. Thanks to the latent heatabsorption and dissipation, the thermal conductivity of heatpipes can be up to 1000 times higher than the thermal conductivity of copper pipes. Due to the high elasticity of the copper pipes, the heat pipe can be easily shaped. In this way, ideal heat paths can be formed inside the hydraulic power unit and the installation space can be considerably optimized. Similar application ranges with equal optimization potential can be found in computer technology. Here, the thermal energy in laptops caused by heat sources such as the CPU are transferred to the central cooling elements using heatpipes.

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Plug & Play: no control cabinet

The frequency converter has a high potential for gaining installation space as well. If it has already been equipped with Multi-Ethernet interface for Sercos, Profinet and other standards by the manufacturer, machine and plant manufacturers are able to reduce the control cabinet requirement for the hydraulic unit by up to 100 percent. As a precondition, however, the sensor technology and the motor in the power unit have to be wired to the frequency converter in such a way that the frequency converter can control the hydraulic pressure autonomously. This means that the control cabinet can not only be designed with smaller dimensions. Sometimes it can even be completely omitted together with the corresponding installation effort and related sources of error.

Conclusion

Fully integrated small power units based on a completely innovative design approach for the performance range up to 4 kW provide machine and plant manufacturers with the advantages of hydraulic drives with very little space requirements. As an alternative to purely electrical solutions, the required energy can be converted into a linear movement in a precise and costeffective manner directly at the working area using a simple hydraulic cylinder. If sensor technology, frequency converter and data interface are integrated as well, users not only benefit from comprehensive condition monitoring but also from a significantly reduced control cabinet footprint or even from a design without control cabinet.
More information fully integrated power units: www.boschrexroth.com/cytropac

Operating principle: https://www.youtube.com/watch?v=sSPemS94G2I

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CMA/Flodyne/Hydradyne is an authorized Bosch Rexroth distributor in Illinois, Wisconsin, Iowa and Northern Indiana.

In addition to distribution, we design and fabricate complete engineered systems, including hydraulic power units, electrical control panels, pneumatic panels & aluminum framing. Our advanced components and system solutions are found in a wide variety of industrial applications such as wind energy, solar energy, process control and more.

Why Rexroth? Top Four Reasons to Choose Rexroth Drives & Controls

Todd Sharp, Motion Control Sales Manager, CMA/Flodyne/Hydradyne

CMA/Flodyne/Hydradyne is a leader in the design and commission of drive and control
systems for our customers for over 30 years, and one question that we often hear is “Why is Rexroth the best?”  There are many brands competing for the drive and control market, and here at CMAFH, we have working experience with most if not all of them. Our engineers program,  repair and upgrade many of the brands of control systems, and we have the ability to integrate any brand into our custom projects at our customer’s request. Having specialized in Bosch Rexroth products for many years, we understand the unique strengths of the product line.

Rexroth drives and controls can be differentiated from competing brands in four very distinct ways.

1. Product Breadth

The IndraDrive product family spans the power range from 100W to 4MW. This product family can operate as an open loop frequency drive/sensor less vector drive up to a multi-axis integrated motion and logic controller that can be either stand alone or drive resident. The IndraDrive product family also includes a cabinet free drive integrated motor. This entire IndraDrive product family is supported by the same software.Indradrive 2016 13187

  • Power range from 100W to 4MW
  • Range of technology from open loop V/F and sensor-less vector control to multi-axis integrated motion and logic control
  •  Integrated motion and logic control – controller or drive resident
  •  Cabinet free drive integrated motor

2. Connectivity

Rexroth’s drive and control platform supports all common communication buses including Ethernet I/P, EtherCAT, Profinet, SERCOS, CANopen, Powerlink, Profibus.
We can control 3rd party motors regardless of brand or type, and we can operate all common feedback types including TTL, 1vpp, Endat, Hiperface, SSI, resolver. Our drives are available with a 2nd encoder input with a 1MHZ input frequency. Our control supports all common machine programming languages like ladder, FB, ST, IL… plus all common IT and engineering languages like C#, C++, Java, Labview, Matlab.

  • Supports all common communication buses including, Ethernet I/P, EtherCAT, ProfiNet, SERCOS, CANopen, Keyvisual_inkl_Logos_w486Powerlink, Profibus
  • Controls all 3rd party motors regardless of brand or technology type
  • Operates all common feedback types (TTL, 1vpp, ENDAT, Hiperface, SSI, resolver) with drive based second encoder input with up to 1MHZ input frequency
  • Supports all common machine programming languages (ladder, FB, structured text, instruction list) plus all common IT and engineering type languages like C#, C++, Java, Labview, Matlab

3. Functionality

Whether it’s drive or controller based, Rexroth offers multi-zone tension control, vibration dampening/anti-slosh control, high speed registration control, advanced electronic camming and hydraulic control. We also support zoned safety control with safe torque off and full safe motion; controller or drive based. Yes, drive based safe motion control!

  • PMK2801_02R_WEBMulti -zone tension control
  • Vibration dampening/anti-slosh control
  • High speed registration control
  • Advanced electronic camming
  • Supports all common hydraulic functions
  • Integrated safe torque off and safe motion control

 

4. Support

Rexroth designs, engineers and manufactures all products they sell. All are standard and sold throughout the world. In the US, hundreds of local high-tech distributors are Rexroth trained and certified to provide full sales, service and application support.  Additionally, Rexroth maintains sales, service and application support facilities in every region of the US, plus scores more globally.

  •  All products are standard and sold throughout the world
  • Bosch Rexroth maintains sales, service and application support facilities in every region of the US and scores more globally
  • In the US hundreds of local high-tech distributors are Rexroth trained and certified to provide additional sales, service and application support

Bosch Rexroth_2012

Do you have questions about this post?  Please contact us:

About CMA/Flodyne/Hydradyne

cropped-cmafh-logo-with-tagline-caps.png

CMA/Flodyne/Hydradyne is an authorized  Bosch Rexroth distributor in Illinois, Wisconsin, Iowa and Northern Indiana.

In addition to distribution, we design and fabricate complete engineered systems, including hydraulic power units, electrical control panels, pneumatic panels & aluminum framing. Our advanced components and system solutions are found in a wide variety of industrial applications such as wind energy, solar energy, process control and more.

Resources:

Engineered Systems Capabilities

Shop for drives online

Indramat Repair Center

Rexroth Drives & Controls Training

Secure Protection from Attacks, Malicious Software and Unauthorized Access

Guest contributors: Gerrit Boysen and Mariam Coladonato, Phoenix Contact

High system availability is very important in process engineering, because ongoing processes must not be interrupted. A fence is a physical, easily identifiable safety measure to secure systems from unauthorized persons. In addition to such physical protections, implementing IT security practices is also becoming more important.

The current trend toward interconnectivity is driving the growing need for IT security in process engineering. Not only is there an increasing number of horizontal interconnections from one system to another, but also the field level is more connected to the office level. In addition, all levels are using more and more Ethernet components. The good news is that this interconnection increases efficiency and reduces costs. The downside of this, however, is that it also increases the risk that malicious software will quickly spread throughout all areas of a company.

In light of this information, process-engineering systems are repeatedly being threatened by new security gaps and a growing number of malicious programs. The computers and control systems used in industrial networks must have much more extensive protection from attacks, malicious software, and unauthorized access than they have so far (Figure 1).

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Figure 1: The Process Analysis Center is protected by a firewall.

The security strategies used in conventional office IT, however, usually are not designed for industrial systems. Industrial networks require special protective measures. The IT systems used in production environments differ fundamentally from those used in office environments in four ways.

  1. Patches cannot typically be applied to industrial systems
  2. Industrial systems use special protocols such as OPC Classic, which are not used in the office world
  3. Large systems can have structurally identical modular assemblies with identical IP addresses
  4. Production systems often require different firewall rules and standards during maintenance and in the event of remote servicing

Office PCs usually have virus scanners that perform security updates at regular intervals. These measures do not normally work for industrial systems for a few reasons. Sometimes, the manufacturer of the operating systems or applications used in the industrial sector no longer provides security updates. In addition, test measures must be performed on industrial PCs before each operating system, antivirus software, or application update, and this cannot be done efficiently in terms of operation.

The use of specific industrial firewalls can protect these non-patchable systems against attacks from outside the network. To do this, hardware-based firewall appliances are connected between industrial PCs and outside networks. Another advantage of using external security hardware is that the system’s resources do not have to be used for security tasks (Figure 2).

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Figure 2: Security example from the process industry.

Targeted restriction of network communications

With firewalls, the user can configure the protocols and ports that can be used to access the protected systems. This can prevent or at least limit the attempt of an attacker to gain access to the network through insecure ports. The Stateful Packet Inspection Firewall approach is an ideal way to manage these systems. This approach uses rules to filter incoming and outgoing data packets in both directions: from the outside to the protected internal network and vice versa. Based on the protocol, source addresses and ports and destination addresses and ports can be used to limit network communications selectively to a defined scope required for production. Here, the Connection Tracking function identifies the response packets on permitted connections and lets them through.

When selecting a suitable firewall, the engineer must ensure that the selected firewall understands any protocols used in the particular industry. Otherwise, reliable protection cannot be guaranteed. For example, office firewalls typically do not support industrial protocols such as OPC Classic, so they cannot provide appropriate protection for the application.

While conventional firewalls cannot reliably protect data traffic via OPC Classic, industrial variants – such as one with a license for OPC Inspector – can provide a suitable solution. The firewall checks the OPC Classic communications data packets and filters them precisely, based on Deep Packet Inspection. For this purpose, the Stateful Inspection principle is also applied to OPC Classic data. This means that the firewall identifies the port changes negotiated in the OPC Classic protocol and approves them dynamically. In this context, it inspects whether a port opened by OPC is used within a timeout period and whether the data traffic moving through this port corresponds to the OPC protocol. This method provides high-access security (Figure 3).

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Figure 3: Deep Package Inspection in the OPC protocol.

Unique and clear mapping to virtual external networks

Complex production sequences are typically structured into networked, largely standalone cells. For an efficient design of the engineering, documentation, and cell operation, the use of identical IP addresses for all systems of a single type proves to be advantageous. If all communications are initiated from the internal cell networks, several identical systems can be connected with simple masquerading NAT (Network Address Translation) routers to the operator’s production network. If the higher level network also needs to establish a connection to the individual cell nodes, however, this solution is not sufficient, because the cell nodes cannot be addressed from the outside. In this case, the user requires a router that can map internal machine networks universally or selectively to unique virtual external networks using 1:1 NAT.

Because of this, an industrial firewall offers the so-called 1:1 NAT routing function, in addition to the pure NAT routing. OPC Inspector, mentioned above, allows this NAT function for the OPC Classic protocol. This sets it apart from conventional office firewalls and other industrial firewalls.

Event-controlled (de)activation of firewall rules

Different firewall rules and standards have advantages in different situations. This is because during production operation or maintenance and remote system servicing, different connections are allowed or forbidden. In practice, the user usually solves the problem by summarizing the various firewall requirements in a set of rules. This procedure inevitably lowers the level of security, because the firewall rules allow all connections required for the different operating states, even if they are not required for the current operation.

An industrial firewall solves the problem by implementing a Conditional Firewall. This function allows the firewall rules to be activated or deactivated depending on events. A variety of events – such as an externally connected button, switch, control window in a web interface, API command line, or establishing or disconnecting a VPN (Virtual Private Network) connection – can be selected to trigger a specific firewall rule (Figure 4).

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Figure 4: Secure remote access to the system.

Summary

The requirements placed on a firewall in a production zone are different from those in the office world. Therefore, using an industrial firewall with a NAT function can support the individual, simple segmentation of networks. This allows the Defense-in-Depth concept based on the ISA-99 and IEC 62443 international standards to be implemented even in systems using the OPC Classic protocol.