Computer-Controlled Electro-Hydraulic Servo Universal Testing Machines

1. Introduction

The WAW series computer-controlled electro-hydraulic universal testing machine adopts a bottom-mounted oil cylinder structure and is equipped with computer-based control and display functions. It is primarily used for tensile, compression, bending, and shearing tests on both metallic and non-metallic materials. This machine is widely applied in industries such as metallurgy, construction, light industry, aviation, aerospace, materials research, higher education, and scientific research institutions. The testing procedures and data processing conform to the standard GB/T 228-2010 Metallic Materials – Tensile Testing at Room Temperature.

ASTMA370, ASTME4, ASTME8, ASTME9, ASTM D638, ASTM D882, ASTM D3039,ASTM, D3479, ASTM E517,ASTM, D695, ASTM D6641, ASTM D3410, ASTM D7791, ASTM D412, ISO6892, ISO527-3, ISO527-4, ISO7438, ISO7500-1, EN10002-4, GB/T228-2002, GB16491-2008, HGT 3844-2008 QBT 11130-1991, GB13-22-1991, HGT 3849-2008, GB6349-1986, GB/T 1040.2-2006, ASTM C165, EN826, EN1606, EN1607, EN12430 etc.

2. Technical Description

2.1 Mainframe

The main unit features a bottom-mounted oil cylinder structure. The tensile test space is located in the upper section of the frame, while the compression and bending test spaces are situated between the lower crossbeam and the worktable.

2.2 Transmission System

The vertical movement of the lower crossbeam is driven by a motor through a reducer, chain transmission mechanism, and screw pair, allowing adjustment of the tensile and compression spaces.

2.3 Control System

Full-Digital Control System:

This system represents the highest level of control technology, providing closed-loop control of test force, specimen deformation, piston displacement, and the overall testing process. It supports control functions including constant stress, constant strain, constant force, constant displacement, force hold, and displacement hold. Additionally, it displays test force, peak value, specimen deformation, piston displacement, and test curves on-screen. All operations are performed via mouse input, with intelligent control mode configuration through an expert system, enabling flexible switching between different control modes.

a) The system supports data processing in accordance with GB/T 228-2022. It allows simulation and replay of the test process and re-analysis of test data. Includes various control modes:

Single-step program control: constant stress, constant strain, constant displacement, force/displacement holding, etc.

Multi-step program control: suitable for tensile tests on metallic materials, etc.

b) Uses a variable structure PID control algorithm to regulate the loading process:

Constant rate control error: ≤ 5%

Holding control error: ≤ 0.5%

Professional software "Control Program Editor" is provided, enabling users to customize specific test control procedures as required.

Test Software Based on Windows OS:

Equipped with a fully digital programmable amplifier, the system automatically performs zero adjustment and sensor calibration. Supports hierarchical user management, multiple graphical interface windows, and unit conversion functionality.

Test Data Management:

Test data is managed through a database and supports network database communication and management.

2.4 Safety Protection Devices

Overload Protection:

If the test force exceeds 2%–5% of the maximum capacity of the selected range, the system will automatically unload.

Stroke Protection:

If the piston reaches the upper limit position, the system will automatically stop the oil pump motor.

2.5 Accessories

A complete set of fixtures is provided, including:

Tensile grips

Compression platens

Bending fixtures

2.6 Others

The equipment package includes installation and debugging tools, sealing parts, user manual, certificate of conformity, packing list, and other technical documentation.

3. Main Technical Specifications

V. Functional Features

Flexible protective covers are installed above the sliding surfaces of the lower crosshead and the grips to prevent oxidized inclusions from falling into the sliding surfaces of the working grips during tensile testing, thereby extending the service life of the grip plates.

The upper and lower grips are equipped with a double-cylinder hydraulic automatic clamping system, controlled by a handheld remote box. This control box enables jog control of the grip clamping/releasing and the lifting/lowering of the lower crosshead.

All components of the product are manufactured under the company's ISO9001 quality management system. Key outsourced components are imported from original manufacturers, effectively improving precision and long-term stability of the equipment.

A unique pressure-following hydraulic control technology is adopted, ensuring the cylinder pressure varies proportionally with the applied load. This reduces noise and oil temperature during operation, while improving hydraulic control accuracy.

The oil source cabinet adopts a uniquely integrated desk-style design with high integration, user-friendly operation, and reduced installation footprint.

Low-noise operation: noise remains below 50 dB even at maximum load, essentially silent. The pressure-following system reduces energy consumption by 70% compared to conventional equipment, and achieves ultra-high control accuracy of up to 0.01% (compared to 0.5% for standard systems). The system features zero control dead zone and 1% control starting point. Highly integrated hydraulic circuits minimize potential leakage points.

Multiple high-speed CPUs work in parallel to enable true multitasking.

Modular unit design allows flexible accessory interchange. The industrial bus-type electrical hardware design facilitates expansion and maintenance.

The modular structure with industrial bus slots simplifies function expansion and maintenance services.

Equipped with a high-precision acquisition card with ±500,000 resolution, fully maximizing sensor measurement range.

Plug-and-Play (PnP) technology of Windows systems is utilized for automatic recognition of inserted cards.

Backup support for sensor correction data ensures high reliability and accuracy in data measurement.

Scene-based operation menu display makes menu switching intuitive and straightforward.

Active crosshead position memory protects preset test positions through software.

Digital counting frequency of up to 10 MHz ensures accurate displacement and elongation measurements with no loss.

Anti-shake frequency-doubling technology for encoder signals greatly improves displacement and elongation resolution.

Full closed-loop control for any channel - not limited to force, displacement, or strain - expands test flexibility.

Rapid and independent overload protection system immediately safeguards equipment in overload conditions.

Three-level crosshead position limit protection provides comprehensive safety assurance.

Software System: Operates on Windows 7 or above; features an elegant and user-friendly interface. Authorization management requires operators to log in with a password before initiating test software.

Versatile Applications: Supports tensile, compression, bending, shear, peel, and tear tests for both metal and non-metal specimens and structural components. Complies with various standards including ISO, JIS, ASTM, DIN, and GB.

User-Friendly Operation: Includes operation wizards and online help for intuitive use.

Automatic Input of Specimen Dimensions: Automatically captures specimen dimensions, reducing manual entry and eliminating potential input errors.

Programmable Testing Methods: Users can program custom test methods to meet specific requirements.

Memory Return: After the test, pressing a button will return the upper grip to the starting position.

Automatic Calibration: Load and elongation can be automatically calibrated based on standard values.

Automatic Recognition: Upon specimen fracture, the system automatically stops and prepares for the next test sequence.

Peak Hold Function: Continuously displays maximum values of test parameters in real time.

Control Modes: Supports displacement control, load control, elongation control, stress control, strain control, constant load, and constant strain control modes.

Programmable Multi-Stage Testing: Up to four stages can be defined. Stage one is preloading, while stages two to four can freely switch among displacement, load, elongation, strain, stress, and speed control, with smooth transitions between stages.

Zeroing Made Easy: Load, elongation, and displacement can be manually zeroed with one button or automatically at the start of a test.

Data Editing: After testing, users can edit data directly on the curve using the mouse.

Unique Displacement Method for Yield Strength: Calculates Rp0.2 for materials without a distinct yield point using the offset method.

Multiple Curve Options: Supports real-time display and switching between various curves such as true stress-strain, engineering stress-strain, load-elongation, load-time, stress-time, strain-time, etc.

Curve Comparison: Enables overlapping and comparison of test curves from the same group; printable results available.

Zoomed-In Analysis: Any segment of the curve can be locally enlarged for detailed analysis.

Custom Report Programming: Test reports can be formatted to meet user-defined requirements.

Automatic Calculation of Key Parameters: Automatically calculates standard values such as

Fm (Fb), Feh, Fel, Fp, Rm (σb), ReH (σsu), ReL (σsl, σs), Rp0.2, Rp0.1 (σp0.2), Rp0.05 (σp0.05), Rp0.5 (σp0.5), E, Et, Ec, Z (ψ), A (δ), τ, etc., in accordance with GB/T 228-2010. Supports multiple output formats for data files.

Powerful Testing Software: Capable of networking with data management software for centralized testing and reporting.

VIII. Working Environment & User Responsibilities

On-site Handling: The user is responsible for unloading and positioning the equipment. The supplier provides free installation and commissioning.

Installation Requirements:

The machine should be installed in a clean laboratory free of corrosive media, electromagnetic interference, or impact/vibration sources.

Ambient temperature: 23 ± 5°C

Relative humidity: ≤80%

Power supply voltage fluctuation: ±5%

Power supply: 380V, 50Hz, three-phase four-wire system (with neutral line N)

Reliable grounding required

Leveling tolerance of base and frame: ≤0.2‰/m

Sufficient space must be reserved for operation, maintenance, and installation of auxiliary equipment.

Hydraulic Oil: User must prepare 100 liters of No. 46 or No. 68 anti-wear hydraulic oil.

Three-Phase Power Supply:

Voltage: 380V, 50Hz (three-phase four-wire system)

Power: 3kW

Voltage fluctuation: ≤±10%

Single-Phase Power Supply (for computer):

Voltage: 220V, 50Hz

Power: 200W

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