tension leveler

Universal Joints

Universal Joints for Multi-roll Tension Levelers
Universal Joints for Nivelador multi-rodillo

Multi-roll tension levelers are essential in the metallurgical industry for flattening metal coils and sheets. They work by passing strip through multiple staggered rolls that impose repeated bending, eliminating residual stress and shape defects to produce a flat, marketable product. At the heart of the drive train, the universal joint (or coupling) connects the gearbox to each leveling roll, transmitting torque while accommodating shaft misalignment. Correctly sizing the universal joint for a strip leveler comes down to two primary parameters: torque value and articulation angle.

1.Product Series Overview

Our company manufactures two main families of constant-velocity ball-type universal joints: fixed–type and plunging (sliding)–type. Fixed-type joints are used where no axial movement is required, while plunging types allow axial stroke during torque transmission, compensating for thermal expansion and roll adjustments. The portfolio includes models such as BJ, DOJ, BOS, BOJ, and BC, covering a torque range from 380 N·m up to 1,000,000 N·m, with rotational diameters from 36 mm to 720 mm. This broad spectrum suits everything from light-duty auxiliary drives to the heaviest rolling mill applications.

2.Torque Calculation: The Primary Selection Criterion

Sizing starts with the required torque. Strip levelers operate under severe shock loads, frequent reversals, and high peak torques that can instantaneously double the nominal value. Therefore, the theoretical torque must be corrected with application factors.

The theoretical torque T is given by:

T = 9550 × P / n

where P is the drive power (kW) and n is the operating speed (r/min).

However, leveler duty is far from steady. According to JB5513 standards, levelers fall under “heavy shock load” category, with a service factor K typically between 2 and 3. The resulting calculated torque Tc is:

Tc = T × K ≤ Tn

where Tn is the nominal torque rating of the coupling. Selection is valid only when Tc does not exceed Tn. For ball-type constant-velocity joints, the load-carrying capacity at the same rotational diameter and angle can be 0.5 to 1 times higher than traditional cross-shaft universal joints, enabling higher torque transmission in a compact envelope.

3.Articulation Angle: Determining the Universal Joints Type

The articulation angle (shaft misalignment) is the second decisive factor. During operation, roll gap adjustments, housing deflections, and thermal expansion create continuous angular offsets between the drive shaft and the leveling roll. Different joint types have different maximum allowable angles:

  • Fixed BJseries allow angles from 14° up to 38°.
  • Plunging BCand DOX series generally permit up to 5°.
  • Plunging DOJtypes can reach 18° in certain designs, with typical working angles between 12° and 22°.

When selecting, the actual operating angle must stay within the specified limit. Also, if the joint experiences misalignment in both horizontal and vertical planes, the combined resultant angle must be calculated. For high-speed, high-angle applications, additional checks on rotational flexibility (e.g., n×β > 18000) may be required.

4.Recommended Selection Procedure

For strip leveler applications, follow these steps:

  • Define torque demand– Calculate required torque based on motor power and service factor, then select a model whose nominal torque exceeds Tc with a safety margin.
  • Define angle requirement– Measure or estimate the maximum shaft angle during operation. For large angles, choose BJ fixed-type; for smaller angles requiring axial movement, choose DOJ or BC plunging types.
  • Confirm rotational diameter– Verify that the coupling’s outer diameter fits within the available installation space, choosing from our range of 36 mm to 720 mm.
  • Consider environmental factors– Dust, heat, and vibration in steel mills may dictate special sealing or lubrication options.

 

Conclusion

Selecting the right universal joint for a multi-roll strip leveler is a balance between torque value and angular capability. With our complete portfolio of fixed and plunging ball-type constant-velocity joints – covering torque from 380 N·m to 1,000,000 N·m and diameters from 36 mm to 720 mm – you can confidently match the coupling to your specific leveler drive. Proper sizing ensures reliable transmission, extended bearing life, and reduced downtime, ultimately contributing to higher productivity and lower operating costs.

For detailed technical data or assistance with your specific application, please contact our engineering support team. We are ready to help you achieve optimal drive performance.

Inquiry: Welcome to contact us for customized model selection and technical parameter confirmation.https://www.ascon.com.cn/

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