Case Study: Extending the Service Life of Vibrating Hydraulic Cylinders in Continuous Casting Machines to Over 12 Months
The vibrating hydraulic cylinders in the mold of a large continuous steel casting plant are required to perform high-frequency, low-speed reciprocating motion over extended periods. After approximately 3–4 months of operation, the original imported standard hydraulic cylinders gradually exhibited issues such as low-speed crawling, unstable vibration, and reduced positioning accuracy, which in turn adversely affected the surface quality of the steel billets.
By improving the machining precision of the cylinder barrel, upgrading the low-friction sealing system, and adding high-temperature-resistant protective structures, Guoyue Hydraulics extended the service life of the hydraulic cylinders to over 12 months—approximately three times that of the original solution.
Customer Requirements and Project Objectives
The customer aims to improve the operational stability and service life of the mold vibration hydraulic cylinders without altering the existing structure of the continuous casting machine.
Key objectives include:
- Eliminating low-speed crawling
- Stabilizing vibration frequency and amplitude
- Improving positioning accuracy
- Adapting to high-temperature, high-dust environments
- Extending the service life of the hydraulic cylinders
- Reducing maintenance and downtime costs
The mold vibration hydraulic cylinders are critical actuators in the continuous casting machine; their operational stability directly affects the mold’s vibration performance, the surface quality of the steel billets, and the continuous operation of the entire production line.
Customer’s Specific Technical Requirements
Capable of High-Frequency Reciprocating Motion
The hydraulic cylinder must perform continuous, high-frequency reciprocating motions over extended periods while maintaining stable response performance.
Smooth Operation at Low Speeds
During low-speed operation, the hydraulic cylinder must not exhibit noticeable crawling, as this would cause discontinuous vibration and fluctuations in amplitude.
Ensuring Positioning Accuracy
The hydraulic cylinder must maintain stable position control over extended periods to prevent deviations in the mold’s vibration trajectory.
Adaptability to High-Temperature, Dust-Heavy Environments
Continuous casting sites are characterized by high temperatures, iron oxide scale, and dust; therefore, the hydraulic cylinder must possess reliable resistance to high temperatures and contamination.
Key Challenges Faced by Customers
The customer originally used standard vibration hydraulic cylinders imported from Europe, with the following key specifications:
Cylinder bore: 160 mm
Stroke: 150 mm
Operating pressure: 210 bar
After approximately 3–4 months of continuous operation, the hydraulic cylinders began to exhibit the following issues:
- Low-speed crawling: The hydraulic cylinder’s motion became discontinuous, resulting in unstable vibration of the mold.
- Decreased vibration stability: Fluctuations in vibration frequency and amplitude affected the stability of the continuous casting process.
- Increased positioning error: As operating time increased, the positioning accuracy of the hydraulic cylinder gradually declined.
- Deterioration in billet surface quality: Unstable mold vibration could cause surface issues such as uneven vibration marks and cracks.
Analysis of the Causes of the Problem
After disassembling and inspecting the returned hydraulic cylinders, the Guoyue Hydraulic Engineering team identified three main causes.
- 1. Excessive friction in the piston seals: The original hydraulic cylinders used a standard sealing design. During low-speed, high-frequency motion, the high startup resistance and friction can easily cause crawling, affecting vibration stability.
- 2. Insufficient machining precision of the cylinder barrel: The roundness error of the original cylinder barrel exceeded design requirements, resulting in uneven force distribution on the seals, increased localized friction, and accelerated seal wear.
- 3. Lack of high-temperature protection design: The original hydraulic cylinder did not adequately account for the high-temperature and dusty environment of the continuous casting site. High temperatures degrade the performance of seal materials, while iron oxide scale and dust can enter the hydraulic cylinder and accelerate wear.
GY Hydraulics Engineering Solutions
Guoyue Hydraulics employs a high-precision honing process to control the surface roughness of the cylinder bore to Ra ≤ 0.2 μm and has upgraded its low-friction composite sealing system, effectively reducing operating resistance and addressing issues such as low-speed crawling and seal wear.
Additionally, a high-temperature-resistant, dust-proof design has been incorporated. The cylinders have passed tests for pressure, internal leakage, high-frequency reciprocating motion, and low-speed operation, ensuring that the vibration hydraulic cylinders are suitable for the high-temperature, high-frequency, continuous operating conditions of continuous casting machines.
| Project Item | Recommended Solution |
|---|---|
| Application Equipment | Continuous Casting Machine Mold Oscillation System |
| Hydraulic Cylinder Type | Mold Oscillation Hydraulic Cylinder |
| Bore Diameter | 160 mm |
| Stroke | 150 mm |
| Working Pressure | 210 bar |
| Cylinder Tube Processing | High-Precision Honing |
| Internal Surface Roughness | Ra ≤ 0.2 μm |
| Sealing Solution | Low-Friction Composite Sealing System |
| Protection Structure | High-Temperature-Resistant Dust Protection Design |
| Quality Validation | Pressure Testing, Internal Leakage Testing, High-Frequency Reciprocating Testing and Low-Speed Operation Testing |
| Solution Objectives | Eliminate Stick-Slip, Stabilize Oscillation, Improve Positioning Accuracy and Extend Service Life |
Project Implementation Results
| Comparison Item | Before Optimization | After Optimization |
|---|---|---|
| Service Life | 3–4 months | More than 12 months |
| Oscillation Stability | Significant fluctuations | Stable operation |
| Low-Speed Operation | Stick-slip occurred | Smooth operation |
| Positioning Accuracy | Increasing positioning error | Long-term stable accuracy |
| Maintenance Frequency | Relatively high | Significantly reduced |
Benefits Realized by the Customer
After implementing Guoyue Hydraulics’ optimization solution, the customer achieved the following:
- Approximately a threefold increase in hydraulic cylinder service life
- The low-speed crawling issue was essentially resolved
- Improved vibration stability of the mold
- Improved surface quality of the steel billets
- Reduced seal replacements and equipment maintenance
- Reduced the risk of unplanned downtime
- Improved operational efficiency of the continuous casting line
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