Mandrel Cylinder Mount Clevis in Roll Forming Machines — Hydraulic Expansion Pivot Guide

Mandrel Cylinder Mount Clevis in Roll Forming Machines — Complete Engineering Guide

Introduction

The mandrel cylinder mount clevis is a structural pivot component used to attach the hydraulic expansion cylinder to the uncoiler mandrel assembly in a roll forming machine.

In hydraulic expanding mandrels, the cylinder generates axial force that drives wedge segments outward to grip the coil. The clevis mount:

• Secures the cylinder body or rod end

• Allows controlled pivot movement

• Transfers expansion force into the mandrel structure

• Accommodates slight angular misalignment

Because mandrels handling 10–35 ton coils operate under high hydraulic pressure, the clevis mount must withstand significant mechanical load while maintaining precise alignment.

Though simple in appearance, it is a critical force-transfer component within the expansion system.

1. What Is a Mandrel Cylinder Mount Clevis?

A mandrel cylinder mount clevis is:

• A forked mounting bracket

• Attached to the mandrel housing or frame

• Designed to accept a clevis pin

• Used to connect the hydraulic cylinder

It forms a hinged connection point.

2. Primary Functions

2.1 Cylinder Attachment

Provides secure mounting point for hydraulic cylinder.

2.2 Pivot Movement

Allows slight angular articulation during expansion.

2.3 Force Transfer

Transfers hydraulic expansion force into mandrel body.

2.4 Load Distribution

Spreads force across mounting structure.

3. Location in the Mandrel System

The clevis is typically mounted:

• At the rear of the mandrel housing

• On the expansion wedge carrier

• On a reinforced frame bracket

• Between cylinder body and structural plate

Position depends on expansion design.

4. Clevis Design

Standard clevis configuration includes:

• Two parallel fork arms

• Clevis pin bore

• Mounting base plate

• Reinforced gussets

The fork shape allows insertion of the cylinder rod eye.

5. Clevis Pin Interface

The clevis works with:

• Hardened clevis pin

• Retaining clip or cotter pin

• Bronze or composite bushing

• Lubrication fitting (optional)

Pin must resist shear load.

6. Hydraulic Force Considerations

During expansion:

• Hydraulic pressure generates axial force

• Force is transmitted through rod

• Clevis transfers force into mandrel structure

Load magnitude depends on coil gripping requirement.

7. Heavy Coil Applications

For 20–35 ton coils:

• Larger cylinder bore

• Higher hydraulic pressure

• Greater force transmission

• Thicker clevis arms required

Structural integrity is critical.

8. Pivot Function

The clevis allows:

• Minor angular movement

• Compensation for frame flex

• Reduction of bending stress on cylinder rod

Rigid mounting without pivot may cause rod damage.

9. Material Construction

Mandrel clevis mounts are typically made from:

• High-strength carbon steel

• Alloy steel plate

• Machined billet steel

• Welded reinforced steel

Material must resist bending and fatigue.

10. Mounting Methods

Clevis may be:

• Welded to frame

• Bolted to reinforcement plate

• Integrated into machined housing

• Reinforced with gusset plates

Mount strength must exceed hydraulic load.

11. Shear Load on Clevis Pin

The clevis pin experiences:

• Double shear load

• Cyclic loading

• Shock load during rapid expansion

Pin diameter must be correctly sized.

12. Stress Distribution

Proper clevis design ensures:

• Even load across fork arms

• Minimal stress concentration

• Reduced risk of cracking

Arm thickness influences strength.

13. Misalignment Protection

If cylinder axis shifts slightly:

• Clevis pivot prevents bending

• Rod seal stress is reduced

• Cylinder lifespan improves

Articulation protects hydraulic components.

14. Vibration & Fatigue

Continuous operation creates:

• Repeated load cycles

• Small oscillating movements

• Long-term fatigue stress

Material selection must consider fatigue resistance.

15. Lubrication Requirements

Some clevis assemblies include:

• Grease fitting

• Bronze bushing

• Oil-impregnated sleeve

Lubrication reduces wear at pivot point.

16. Wear Points

Common wear areas include:

• Pin surface

• Bushing inner diameter

• Clevis bore

• Mounting holes

Regular inspection prevents elongation.

17. Failure Risks

If clevis fails:

• Cylinder may detach

• Expansion mechanism becomes unstable

• Mandrel gripping fails

• Severe mechanical damage may occur

Clevis integrity is essential.

18. Installation Procedure

Proper installation includes:

1. Aligning cylinder rod eye between fork arms

2. Inserting clevis pin

3. Installing retaining clip

4. Checking smooth pivot movement

5. Verifying no excessive clearance

Correct fit ensures stability.

19. Alignment Considerations

Clevis must align with:

• Cylinder axis

• Mandrel expansion direction

• Wedge carrier movement

Misalignment increases rod side loading.

20. Corrosion Protection

Clevis mounts are typically:

• Painted

• Powder coated

• Zinc plated (pins)

• Greased at pivot

Corrosion weakens structural capacity.

21. Replacement Criteria

Replace clevis or pin if:

• Bore elongation visible

• Crack formation detected

• Pin wear exceeds tolerance

• Excessive play develops

Wear leads to alignment instability.

22. Engineering Design Factors

Engineers evaluate:

• Maximum hydraulic pressure

• Cylinder bore size

• Required expansion force

• Shear capacity of pin

• Safety factor

Design must exceed peak load.

23. Relationship to Mandrel Expansion System

The clevis connects:

Hydraulic Cylinder → Clevis → Mandrel Frame → Expansion Wedge

It is a primary force-transfer link.

24. Safety Role

The clevis ensures:

• Secure cylinder mounting

• Controlled expansion motion

• Safe coil gripping

• Stable expansion force application

Failure can compromise entire uncoiler system.

25. Summary

The mandrel cylinder mount clevis is a structural pivot component that connects the hydraulic expansion cylinder to the mandrel assembly in a roll forming machine.

It:

• Transfers hydraulic force

• Allows controlled pivot movement

• Protects cylinder from side loading

• Supports heavy coil expansion

• Ensures stable mandrel gripping

Though compact, it is a critical load-bearing component in hydraulic mandrel expansion systems.

FAQ

What does a mandrel cylinder mount clevis do?

It connects the hydraulic cylinder to the mandrel structure.

Why is pivot movement important?

It prevents side loading on the cylinder rod.

Does it carry heavy load?

Yes — it transfers full hydraulic expansion force.

What happens if it wears out?

Alignment issues and unstable expansion may occur.

Is it critical in heavy coil systems?

Absolutely — higher hydraulic force requires stronger clevis design.