NETFORM Rotor Shaft Capabilities

LIGHTWEIGHT, HOLLOW EV ROTOR SHAFTS

NETFORM ROTOR SHAFTS

NETFORM has developed two advanced forming processes for the manufacture of lightweight, high-strength, advanced cooling rotor shafts.

The first technology involves utilizing flowforming to manufacture rotor shafts. The second option uses press-forming.

An overview of these processes, along with a collection of design ideas/concepts, are shown in the following slides.

NETFORM’s Rotor Shaft

Philosophy/Approach

INTEREST

Solid Shafts

NETFORM’s EV ROTOR SHAFT FOCUS

Machined Hollow Shafts

Formed Hollow Shafts

Formed Hollow Shafts w/ Cooling

Formed Hollow Shafts w/ Electronics

DIFFICULTY

EARLY COLLABORATION IS KEY

This is the key point to successful product design at the lowest cost. The key elements are as follows:

• Early NETFORM involvement in product design.

• Cross functional customer team – product engineering, manufacturing engineering, and purchasing

• Review of the cross sections of the motor concept as a whole.

• Reviewing system costs that include assembly costs, components costs etc.

• Incorporating manufacturing process tolerance capabilities into the product print tolerances where possible.

Collaborate Design

Manufacturing

NETFORM’S ROTOR SHAFT MANUFACTURING PROCESS

Hot Forged

Preform Cold Formed

Preform

Stamped Blank

SHAFTS - MANUFACTURING OPTIONS

NETFORM has two main processes for the manufacture of rotor shafts. These are press forming and flowforming.

Both process can utilize a variety of preforms depending on the application, as well as allow for part consolidation. In addition, press forming of shafts allows for non-round/splined shafts to be formed

(Flowformed or Press Formed)

Flowforming Process Video Cold Forming Process Simulation

NETFORM ROTOR SHAFTS - 1

The following are a few examples of the rotor shafts that NETFORM can provide:

2 Piece Shaft with center support/weld and coolant control units

1 Piece Shaft with integrated components

2 Piece Shaft with end weld and cap

NETFORM ROTOR SHAFTS - 2

Formed OD Splined Shaft

Technical Section

MATERIAL & HEAT TREAT SELECTION

The most critical aspect of the product design phase is determining the material, heat treatment and process that meets the customer’s technical and fiscal needs

• Material

• 4140

• 1045

• 1035

• 5120 mod/20MnCr5

• Geometry

• Tolerances

• Strength

• Hardness

• Weight CUSTOMER

• Work hardening

• Induction hardening

• Vacuum carburizing

• Ferritic nitro carburizing

Lowest Cost Solution

• Formability

• Manufacturing processes

• In-process heat treatments

• Finished part heat treatment options

• Process cost

• Work hardening

• Laser weldability

• Surface hardness options

• Cold Forming

• Flowforming

• Cold Drawing

• Necking

MATERIALS, STRENGTH & HARDNESS DATA

Cooling

COOLING OPTION 1 IN-PROCESS COMPONENT INCLUSION

Hollow electric rotor shaft with uni-directional coolant flow

• Incorporating the shaft manufacturing process into the shaft design can reduce the shaft overall cost.

• Coolant flow tubes or components can be incorporated “mid-process” as opposed to being secondary activities.

Preform Form Shaft

Insert Tube Neck Shaft

COOLANT OPTION 2 COOLANT CONTROL COMPONENTS

• The shaft can be designed to incorporate coolant control components.

• The components can be plastic/nylon or metal.

• Longer shafts can benefit from the center unit providing additional shaft stiffness

COOLANT OPTIONS 3 INTERNAL PROFILE MODIFICATIONS

Surface area increase – rotor ID

The forming of internal spline can be used to increase the surface area of the inside of the tube and hence the heat transfer capabilities.

Surface area increase of up to 70% over traditional tubing.

Fins can be formed/trapped into the shaft to increase turbulence/redirect coolant flow.

COOLING OPTION 4 O.D. PROFILE MODIFICATIONS

• The ability to press form the rotor shaft allows freedom to vary the outside profile of the shaft.

• This freedom can be used to improve the assembly process of pressing the laminates onto the saft.

• It can also be used to prevent the rotation of the laminates on the shaft itself.

• Finally, it can provide cooling options on the outside of the shaft as shown.

Oil flow channels

Laminate keyway

Laminate

Oil flow channels

COOLING OPTION 5 HEAT SINK INCORPORATION

Rotor shaft with internal spline

Alternate teeth "missing" to allow flow past and across heat sink.

Working with the shaft internal profile, a coolant direction shell and the heat sink outer profile, coolant flow can be directed as required through the shaft.

OD designed to fit in rotor spline