LBTZX-1A Bidirectional Compression Bellows Longitudinal Load Testing Machine

Product Introduction:

This apparatus complies with the transportation industry standard JT/T 529 for plastic corrugated ducts used in prestressed concrete bridges and is employed to determine the local longitudinal load‑bearing parameters of such ducts. For the longitudinal load‑performance test, a 1100‑mm‑long segment of the plastic corrugated duct is selected, without an internal liner; a longitudinal load N is applied and maintained for 10 minutes, during which the applied load before and after, as well as the axial compression of the duct segment, are recorded, and the amount of compression is calculated.

Based on the standard:

1. Plastic corrugated ducts for prestressed concrete bridge girders, per JT/T 529

2. GB/T 18477.1 Buried Drainage Systems Using Rigid Polyvinyl Chloride (PVC-U) Structural-Wall Pipe Systems — Part 1: Double-Wall Corrugated Pipes

3. GB/T 21238 “Glass Fiber Reinforced Plastic Sand-Clad Pipe”

Product Features:

1. The testing machine features a horizontal, double‑screw gantry structure with a single test chamber; the central section serves as the compression space, used for test‑force calibration and longitudinal compressive loading tests on bellows, with both moving beams operating in tandem.

2. The testing machine’s mainframe is designed to be aesthetically pleasing, easy to operate, and characterized by stable, reliable performance; it produces no pollution, operates with low noise, and delivers high efficiency. The auxiliary fixtures are matched to the mainframe, featuring a wedge‑type linear‑motion design with manual rotary clamping, ensuring that the specimen is subjected to no additional forces. Clamping is convenient, secure, and prevents slippage.

3. This testing machine employs a high‑precision, stable AC servo drive system and motor as its actuation unit; a specially designed synchronous toothed belt reduction system and ball screw assembly drive the moving crosshead. The control and data‑processing software, built on a Windows platform and leveraging database technology, utilizes virtual instrumentation to replace conventional digital displays and oscilloscopes, enabling on‑screen visualization of test force, peak test force, crosshead displacement, specimen deformation, and test curves. All testing operations can be performed via mouse input directly on the computer screen, offering an intuitive human–machine interface and convenient operation. A dual‑channel, fully digital, microprocessor‑controlled amplifier installed in the PC achieves true physical zeroing, gain adjustment, and automatic range switching, zeroing, and calibration for test force measurement—eliminating all analog adjustment components. The control circuitry is highly integrated, with potentiometers and other mechanical adjustment elements removed, resulting in a simplified structure and reliable performance. The combined application of these technologies ensures closed‑loop control of parameters such as test force, specimen deformation, and crosshead displacement, supporting tests under constant force, constant displacement, constant strain, as well as constant‑rate load cycling and constant‑rate deformation cycling. Users can employ the PC‑based expert system to independently configure control modes—including constant stress, constant strain, and constant displacement—and seamlessly switch between them. Notably, the system boasts excellent scalability, allowing test results to be stored on disk in ASCII format, thereby facilitating post‑processing tasks such as data reanalysis, database management, and network transmission.

4. Since this testing machine achieves automated control of the testing process and digital processing of test results, operators can conveniently and independently configure programmed test steps. During tensile testing, the entire test procedure—such as that of low‑carbon steel or cast iron—can be observed clearly. By repeatedly applying loads across different segments of the load–displacement (deformation) curve, Hooke’s law can be visually verified, and work hardening can be readily observed. For materials that do not exhibit a distinct physical yield point, the hysteresis loop method or the stepwise approximation method may be employed to determine the specified non‑proportional extension strength. In compression tests, it is easy to observe the yielding and strain‑hardening behavior of low‑carbon steel, as well as the compressive failure mode and fracture surface of cast iron. Furthermore, the n‑value and r‑value of mechanical materials can also be determined.

II. Structure and Principle:

The testing machine comprises an upper crossbeam, a pair of movable crossbeams, and a worktable, all connected by vertical columns and T‑type lead screws to form a rigid bench‑type frame. An AC servo motor and an AC servo speed‑control system are mounted beneath the worktable. The AC servo motor drives a pair of ball screws via a synchronous toothed belt reduction mechanism, causing the movable crossbeams to move vertically and thereby apply load to the specimen (compression with dual movable crossbeams). A load cell is installed on the underside of the movable crossbeams to measure the magnitude of the test force.

III. Performance and Features:

1. The testing process is controlled by an AC servo motor and an AC servo speed‑control system, significantly enhancing control accuracy and quality. The system operates smoothly, efficiently, and with low noise—virtually silent at low speeds—and offers an expanded speed range of 0.05–300 mm/min. This makes it well suited for low‑speed testing of conventional materials (such as metals, cement, and concrete) as well as high‑speed testing of non‑metallic materials (e.g., rubber). It can also be used to rapidly adjust the test gap under no‑load conditions, thereby reducing auxiliary testing time. The available test speeds meet the requirements of all standard domestic tests for both metallic and non‑metallic materials.

2. The reduction mechanism, comprising a synchronous toothed belt and a precision ball-screw pair working in tandem, results in a simpler, more streamlined design, significantly enhances transmission efficiency, and lowers both the height of the machine’s lower worktable and the overall machine height, yielding a more harmonious appearance.

3. It adopts a dual‑space structure with separate tension and compression chambers, offering convenient operation and eliminating the hassle of switching between different test fixtures when performing tension and compression tests in the same space.

4. Sensors of various specifications can be configured as required, significantly expanding the test range to meet measurement needs across different test loads.

5. The host features an all‑plastic‑coated enclosure, with a sleek and aesthetically pleasing design.

6. Employing advanced control technology, the system features three closed-loop control modes—stress, strain, and displacement—with automatic switching between them and seamless, shock-free transitions during mode changes. It can simultaneously display test force, peak value, displacement, velocity, test status, and test curves.

7. It can perform rate-controlled testing and maintain specified rates for test force, deformation, displacement, and other parameters.

8. The crossbeam can be raised or lowered at fast or slow speeds during specimen clamping, offering flexible operation and seamless switching between modes.

9. Features automatic return to the initial position after testing, ensuring high efficiency and speed.

10. Equipped with comprehensive limit‑position protection, overload and overcurrent protection, and automatic stop upon specimen fracture, ensuring reliable and safe operation.

11. A robust, in-house experimental database has been developed, enabling experimental data to be saved, queried, and accessed at any time.

12. Provides multiple report-printing interfaces, enabling users to customize reports in any format and print them as needed.

13. The entire control system offers excellent cost-effectiveness and high reliability.

14. Conduct tensile tests on materials in accordance with national standards or user‑specified criteria, perform statistical analysis and processing of the test data, and generate and print various required test curves and reports. The system offers real-time display, zoom, comparison, and traversal functions for load–time, load–displacement, displacement–time, and deformation–time curves, along with comprehensive monitoring of the testing process—intelligent and convenient.

15. A “Standard Add‑On Program Editor” software is provided for professional users, enabling them to flexibly add the required standards according to their specific needs.

16. The test software, fully localized in Chinese and running on the Windows platform, features robust data and graphical processing capabilities. It can generate complete test reports and plot test curves in real time, and includes a reserved data interface for direct integration with an enterprise’s (or laboratory’s) comprehensive information management network. Customization is also available to accommodate the specific requirements of the user’s local area network.

Technical Specifications: