Author: claire Publish Time: 2024-05-21 Origin: Ma‘anshan Tianjun Machinery Manufacturing Co., Ltd.
Resilient wheels are a type of wheel in which rubber is embedded between the wheel rim and the wheel hub. Typically, they consist of a wheel rim, wheel hub, pressure ring, rubber ring, and connecting bolts. Resilient wheels are one of the main wheels used in modern urban rail transit vehicles. They can reduce wheel-rail impact noise, alleviate wheel-rail impact vibrations, reduce the dynamic stress on transmission and steering frame devices, decrease wheel-rail wear, and extend the service life of vehicles on the track. With the rapid development of rail transit, the role of resilient wheels has become increasingly important. They have become a key component of rail vehicles, and market demand is growing.
This article uses the example of a certain export-type integral resilient wheel produced by our company to introduce the design of the pressing equipment and tooling, intelligent rubber pressure monitoring, and balanced compression installation method for such resilient wheels. The aim is to address issues such as large runout after pressing, uncontrolled preloading force and pressing speed, and the inability to detect rubber pressing force in real-time.
Through systematic analysis and design, we have developed a general-purpose assembly equipment and tooling for resilient wheels, an intelligent rubber pressure monitoring system, and a balanced rubber compression installation method. Practical application and verification have effectively reduced the runout of resilient wheels after assembly. By monitoring the rubber preloading force, we indirectly controlled the test stiffness of resilient wheels, reduced the sampling ratio for stiffness tests, and created a pressure curve table for each resilient wheel assembly. This ensures assembly quality and improves efficiency.
The export-type integral resilient wheel mainly consists of a wheel hub, rubber ring, wheel rim, grounding wire, and fastening bolts.
1.Wheel Hub
2.Rubber Ring
3.Wheel Rim
4.Grounding Wire
5.Fastening Bolts
(Figure 1: Structure of the Export-Type Integral Resilient Wheel)
1. Bolt Torque: 300N·m
2. Axial Runout: ≤0.5mm
3.Radial Runout: ≤0.3mm
4.Static Imbalance: ≤125g·m
5.Type Test Requirements:
- Radial Stiffness: ≥400kN/mm
- Axial Stiffness: ≥65kN/mm
- Torsional Stiffness: 23.9kN/mm
- Hysteresis: ≤0.3mm
6.Fatigue Test Requirements:
- No defects detected on the wheel rim, wheel hub, and pressure ring surface through magnetic particle inspection after the test; hysteresis ≤10mm
- The variation rate of axial and radial runout values before and after the torsional stiffness test: ≤±20%, with axial runout ≤0.5mm and radial runout ≤0.3mm
- After the test, the stiffness values must meet the requirement of 600kN/mm ≥ radial stiffness ≥ 320kN/mm, 100kN/mm ≥ axial stiffness ≥ 52kN/mm
Product Runout: The export-type product has the same basic structure as a domestically developed light rail resilient wheel, but with higher requirements for assembly runout values.
Stiffness Test: With the large batch of export-type resilient wheels, ensuring each product meets stiffness test requirements is challenging. By controlling the minimum rubber pressing force and sampling resilient wheel stiffness, we can monitor the stiffness test indirectly. The acceptable axial pressing force range is determined to be 12.5~16t.
Control preloading force, pressing speed, and holding time.
Output the actual rubber pressing force.
Record and save quality data.
Main Equipment Design: The hydraulic cylinder is installed in the middle of the machine body with the piston rod facing upward. Using a segmented composite block to pull and press the product ensures no pressing components obstruct the upper part of the resilient wheel, facilitating manual tightening of bolts around the wheel.
Supporting Tooling:
- Hub Spacer Block: Used for end face positioning of the resilient wheel before and during pressing.
- Hub Positioning Block: Used for radial positioning of the resilient wheel before and during pressing.
- Pressure Block: Used for balanced pressing of the resilient wheel pressure cap during pressing.
- Rim Adjustment Device: Used to pre-adjust radial eccentricity before pressing the resilient wheel with rubber onto the equipment.
Pressing Speed Design: The equipment uses an electro-hydraulic servo CNC hydraulic press, a PLC programmable controller, and an industrial computer to collect and process data, allowing for the setting and adjustment of the hydraulic cylinder’s pull pressure and speed. During the entire pressing process, the initial part of the stroke is set at 3~4mm/s, and the latter part at 0.5~1.5mm/s.
Pressure Holding Design: After the resilient wheel is pre-pressed into place, bolts or nuts are manually placed and sequentially tightened by two people from opposite sides. The pressing equipment must have a pressure holding function, and the parameters are set based on the product’s specific holding time requirements.
During the pre-pressing of the resilient wheel, once the wheel cover is in full contact with the wheel hub step, the hydraulic cylinder pressure continues to increase without causing piston displacement. The corresponding pressure value at the turning point of the displacement-pressure curve, plus the weight of the rim and rubber, is the axial pressure on the resilient wheel’s rubber. The equipment measures this through pressure and displacement sensors, drawing the displacement-pressure curve to monitor the axial pressure in real time.
Interference Fit of Rubber and Rim: The outer diameter of the rubber and the inner diameter of the rim use an interference fit, with a general interference amount of about 3mm.
Rubber Ring Compression Method: Compress both sides of the rubber ring simultaneously into the rim, adjust the remaining sides to have roughly equal compression, and use a rubber mallet to evenly tighten the compressed parts, ensuring uniform pressure distribution.
Pre-pressing Method to Eliminate Uneven Stress: Pre-press the wheel once before the official pressing, holding the pressure for 3-5 minutes to release part of the concentrated stress, resulting in more uniform and tight contact between the rubber, rim, hub, and pressure ring.
After designing automated pressing equipment and improving the rubber pressing method, batch production of export resilient wheels shows significant improvement in assembly runout quality. Stiffness and fatigue tests meet the requirements, and all performance parameters fully comply with the quality standards of the export resilient wheels.
The research and implementation of this resilient wheel assembly process have advanced our company’s assembly technology to a leading level, ensuring pressing quality and monitoring effectively. Product quality has been verified by tests in a CNAS-accredited laboratory and customer usage, meeting all requirements.
