Bosch Rexroth Sytronix: Pump-Controlled Hydraulic Drives for Press Brakes

Introduction

Hydraulic press brakes are increasingly equipped with variable speed drives for energy savings. Bosch Rexroth's Sytronix solution utilizes intelligent drives with optimal set-point values for torque and speed to tailor performance to each phase of the cycle. This approach maximizes energy savings, especially in partial-load operation, by supplying only the necessary power for movement and deformation.

Sytronix systems offer energy savings of up to 50% and reduce noise emissions by up to 10 dB(A). The components are configured according to a modular design principle and can be extended with tool clamping and crowning options. Sytronix is part of Bosch Rexroth's 4EE strategy for energy reduction in machines and systems.

More & Less – The universal process for optimum energy efficiency

Optimizing energy efficiency across the entire machine lifecycle requires a holistic approach. Bosch Rexroth leverages its expertise to identify and capitalize on energy-saving potentials throughout the design, construction, engineering, commissioning, operation, and modernization phases.

Key benefits of variable speed drives and Sytronix:

• More: Increased plant utilization, simplified integration of Rexroth components for status monitoring and diagnostics, end-to-end automation for reduced downtime, elimination of throttling losses, precise oil quantity metering via servo motor dynamics.
• Less: Up to 50% energy savings, reduced operating costs (TCO) and CO2 emissions, up to 10 dB(A) noise reduction, potential for reduced investment costs (e.g., cooling systems), electric drives capable of multiple overloads, 4Q pumps for wide speed ranges, optimized fluid reservoirs, and reduced space requirements due to high hydraulic power density.

Standard Systems and Hydraulic Parameters

The following table outlines standard systems and hydraulic parameters based on press force, pump size, and pre-fill valve size.

Note: Information/characteristics are approximate values and serve for initial system design. Additional oil velocities regarding diameter and length of oil lines must also be considered.

Questionnaire for the Dimensioning of Sytronix Pump-controlled Solutions for Press Brakes

This questionnaire helps in dimensioning Sytronix pump-controlled solutions for press brakes by gathering essential system parameters.

System parameters / details / design criteria:

• Cylinder: Piston diameter, Piston rod diameter, Stroke, Number of cylinders, Distance between cylinders.
• Forces and pressures: Max. required pressing force, Weight ram (incl. bending beam, without tool).
• Positioning accuracy: Repeat accuracy.
• Safety regulations and functions: CE guideline EN 12622, Other regulations/standards.
• Selectable options: Hydraulic crowning (filling capacity, filling pressure, filling time), Hydraulic upper tool clamping (with accumulator, filling capacity, filling pressure, filling time - clamping open/closed), Hydraulic lower tool clamping (with accumulator, filling capacity, filling pressure, filling time - clamping open/closed).

Flow Diagram: The diagram illustrates the position and speed profiles during a press brake cycle, including standstill, rapid downward, creep speed, pressing, decompression, and rapid upward phases.

Components and Structure of a Sytronix System

Sytronix systems offer pre-configured solutions for variable speed pump systems in press brakes. The basic schematic involves a PLC/CNC, motion controller, servo drive, servo motor, 4Q axial piston pump, and a manifold block. The system achieves efficiency by eliminating throttling losses and precisely metering oil quantity.

Efficiency improvements include:

• Elimination of throttling losses at control valve edges.
• Precise oil quantity metering via servo motor speed control.
• No idle power as the E-motor can be switched off when not needed.

Positive impacts on environmental aspects and operating costs:

• Reduced energy consumption, costs, and CO2 emissions.
• Reduction of installed power (smaller E-motor possible due to overload capability).
• Reduced tank volume.
• Reduced or eliminated media cooling.
• Noise reduction due to optimized rotational speed.

Sytronix system: Structure of a press brake cylinder axis

The system comprises a PLC/CNC, servo drive, servo motor, 4Q axial piston pump, cylinder, and manifold block. A suction/pre-fill valve is also included.

Sytronix System – Hydraulic Circuit Diagrams

The document provides detailed hydraulic circuit diagrams for two configurations:

• Hydraulic Circuit Diagram with Single Block: Suitable for sizes NG6, 10, 16. Features include a pre-fill valve SFA/ZSF..., short suction lines, and delta-p optimized X2 lines.
• Hydraulic Circuit Diagram with Central Block: Suitable for sizes NG6, 10, 16. Recommends central placement of the block and motor-pump systems between cylinders, equal line lengths, delta-p optimized X2 lines, and use with cylinders having a distance < 3 m.
• Hydraulic circuit diagram – "dissolved" construction: Details the system with recommendations for oil speeds in suction lines, low pressure lines, and pressure lines, along with information on hydraulic piping design (minimize deflections and fittings, optimize pipe diameter).
• Hydraulic circuit diagram – "power unit" construction: Shows a standardized power unit solution where Rexroth assembles the complete Sytronix power unit. Includes recommendations for oil speeds and hydraulic piping design.

Sytronix Solution for Press Brakes

"Dissolved" construction: Allows for individual solutions where Rexroth handles system engineering, and the customer procures components individually. A parts list of an exemplary Sytronix solution is provided.

"Power unit" construction: Bosch Rexroth offers standardized power unit solutions, with system engineering performed by Rexroth and components assembled into a ready-to-install unit.

Parts list of an exemplary Sytronix solution: Lists components such as Main manifold block, Fixed displacement pump, Suction block, Pump carrier, Damping ring, Clamp hub pump, Gear ring, Clamp hub motor, Return filter, Filter element, Inline filter, Filter element, Filter display, Cable socket, plug, cable sets, Tank ventilation filter, Pre-fill valve, Servo motor, Servo drive (incl. control section), Mains choke, Mains filter, Motor power cable, Motor encoder cable, etc.

Nomogram for Determining the Pipe Inside Diameter

A nomogram is provided to determine the pipe inside diameter (DN) based on flow rate (Q) and oil velocity (v). The formula DN = √ (Q x 400) / (v x 3.14 x 6) is also given.

Recommended oil speeds:

• Suction lines: approx. 0.5 - 1 m/s (line in green)
• Low pressure lines: approx. 2 - 4 m/s (line in blue)
• Pressure lines: approx. 5 - 12 m/s (line in red)

Overview of Variants for Crowning and Tool Clamping

Details various options for crowning and tool clamping, including filling capacity, filling time, and mechanical/proportional pressure adjustments for both upper and lower tool clamping. Example representations and combinations on HSR plates are shown.

• Crowning: With precise pressure control or standard pressure control.
• Tool clamping - upper tool: With electrical pressure switch, mechanical pressure adjustment, accumulator, accumulator pressure protection, and tool clamping in basic position "open" or "closed".
• Tool clamping - lower tool: With electrical pressure switch, mechanical pressure adjustment, and tool clamping in basic position "open" or "closed".

Components and Accessories

This section details various components and accessories available for the Sytronix system:

• Power units for additional functions: Examples include CPM-MT, K, KE, KS compact power modules with advantages like high flow rate, high pressure capability, and AC motors up to 5.5 kW.
• E-Motors: MS2N and MSK series with details on efficiency categories, continuous torque, and maximum torque/speed.
• Pumps / Motors: Axial piston units (Type: A10FZG) for variable speed operation, suitable for four-quadrant operation and featuring proven A10 rotary group technology.
• Suction / pre-fill valves: Types SFA, ZSF and ZFSW, and SFE with specifications on sizes and maximum pressure.
• Pressure / line filters and filter elements: With nominal pressure up to 400 bar, various nominal sizes, bypass indicators, and filter fineness options.
• Return filters and filter elements: With nominal pressure up to 10 bar, various nominal sizes, bypass indicators, and filter fineness options.
• Cable / Plug: Mating connectors and cable sets for valves and sensors.
• Pressure transducer: Type HM20 for hydraulic applications, with measurement ranges up to 630 bar.
• Pressure switch: Type HEDE11 with 2x antivalent switching outputs and simple adjustment.
• Amplifier: Connector switching amplifier with pulse width modulation (PWM), Type VT-SSBA1-PWM-1X/V002/5, for controlling switching valves.
• Components control cabinet: Includes IndraDrive Cs compact converters (HCS 01, HCS02, HCS03) with various power ranges and overload capacities. Also details IndraDrive control sections CSB02 for HCS02 and HCS03, offering integrated safety technology and multi-Ethernet interfaces. IndraDrive mains filters (HNF01, NFD03) and choke (HNL01) are also described, ensuring EMC compliance and harmonic reduction.

Basic Parameterization of the IndraDrive Drive Controller for HCS01, HCS02 and HCS03

This section provides an excerpt of the basic parameterization for HCS01, HCS02, and HCS03 drive controllers. It covers installation, wiring, and connection of the servo motor and control sections. Key aspects include:

• HCS01 Parameterization: Details wiring of the drive controller, servomotor connection (power cable, brake/temperature contact, encoder cable), and the importance of the Bb relay contact for readiness signaling.
• HCS02/CSB02 Parameterization: Explains the connection and wiring diagram for the HCS02 drive controller and CSB02 control section, including power section and control section connection points.
• Electrical Connections: A detailed table lists connection points (X4, X8, X10, X24, X25, X30, X31, X32, X33, X35, X37, X38, X41, X42/X43, X48, X49, X61, H1) and their descriptions for encoder evaluation, communication, digital/analog inputs/outputs, safety technology, and operating panel interface.
• Digital Inputs/Outputs (X31): Describes the function and default assignment of digital inputs and outputs, including probe inputs, E-Stop input, and travel range limit switch inputs.
• Digital Inputs/Outputs (X37 - DA option): Details the use of the optional X37 module for defining ready signals and outputs, and the assignment of control word bits for controller enable and drive stop.
• Analog Inputs/Outputs (X38 - DA option): Explains the assignment of analog inputs/outputs for speed set points and torque limit values.