Expandable Winding Mandrel for Transformer Coils Winding

Product Introduction

The TRANFOVIA expandable winding mandrel supports transformer coil winding across a wide range of inner diameters and coil weights. Its reducer-driven expansion mechanism holds the required diameter during winding, then contracts for controlled coil removal without forcing or distorting the finished winding.

A Reusable Winding Form That Releases the Coil

A fixed winding form must match one coil diameter, and removing a tightly wound coil can require significant lifting force or additional handling. An expandable mandrel changes the process: the mandrel is expanded to the specified winding diameter, supports the conductor and insulation during production, and is reduced after winding so the coil can be removed with less mechanical interference.

This makes the mandrel especially useful for transformer factories producing multiple coil sizes or heavy coils that require stable support throughout winding. Twelve standard capacity ranges cover nominal diameters from 180 to 3000 mm and loads from 1 to 20 tons.

How the Expandable Winding Mandrel Works

Mandrel Architecture

• Cage Forms the main rotating framework and carries the expansion assemblies around the mandrel circumference.
• Sliding Sleeve Assembly Converts reducer movement into controlled axial motion for diameter adjustment.
• Support Rod Assemblies Transfer movement from the sleeve to the battens and support the expanded winding surface.
• Basic Battens Create the primary cylindrical surface for the model’s working-diameter range.
• Additional Support Battens Increase the effective diameter for the upper portion of a configuration’s range.
• Transmission System Provides reducer-based adjustment for controlled expansion and contraction.
• Right-Angle Limiter Helps define and stabilize the working position of the expansion structure.

Why Diameter Accuracy Matters

The winding mandrel determines the initial inner geometry of the transformer coil. Excessive diameter variation can affect the coil’s roundness, insulation fit, support blocks and subsequent assembly with the core or adjacent windings. The mandrel maintains diameter deviation below 1 mm between any two measured points and cylindricity below 1 mm, providing a controlled reference surface for winding.

Technical Parameters

Information Required for Quotation

• Coil drawing with inner diameter, outer diameter and axial length.
• Maximum finished coil weight and temporary winding-fixture weight.
• Required working-diameter range and production size mix.
• Winding machine shaft, center height, torque and connection details.
• Conductor type, insulation structure and expected winding tension.
• Coil lifting and unloading method after mandrel contraction.
• Required documentation, inspection and acceptance criteria.

FAQ

1. What is an expandable winding mandrel used for?

It provides an adjustable cylindrical support for transformer coil winding and contracts after winding to create clearance for coil removal.

2. What diameter range is available?

The available configurations cover nominal winding diameters from 180 to 3000 mm.

3. What is the maximum load capacity?

The largest standard configuration supports a load of up to 20 tons. The correct selection depends on coil weight, mandrel length and winding-machine interface.

4. What do the additional battens do?

Additional support battens increase the effective winding diameter for the upper section of a configuration’s working range.

5. How accurate is the winding surface?

Diameter deviation between any two points is below 1 mm, and cylindricity is below 1 mm.

6. How is the diameter adjusted?

The standard configurations use reducer-driven adjustment to expand or contract the supporting battens.

7. Can one mandrel replace every fixed winding form?

No. Each configuration has a defined diameter, load and batten-length range. Several configurations may still be required for a factory with a very broad product mix.

8. What information is needed to select a mandrel?

Provide the coil inner diameter, axial length, total winding load, winding-machine interface and required removal clearance.