Control Techniques
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Leroy-Somer
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Remote I/ORotary Shear for 15 mm Plate: One Knife on 2 × 250 kW Motors, CODESYS RTE and EtherCAT
By the ONX Control engineering team · Published:
In short
On this machine, plate about 2 m wide and up to 15 mm thick is cut to length by a single-knife rotary shear without stopping the line. The knife drum is turned by two 250 kW Leroy-Somer CPLS induction motors, each fed by its own Control Techniques Unidrive M701 drive; the current loops of both drives run in sync over EtherCAT. Control runs on CODESYS Control RTE on an industrial PC with a 250 µs EtherCAT cycle, and the knife follows the line encoder. The line runs at 10–80 m/min, cut lengths range from 200 mm to 10 m, it reaches up to 90 cuts per minute, and the length tolerance is ±0.5 mm.
Project summary
- Industry
- Metal: plate cutting
- Machine
- Rotary shear, one knife per revolution
- Material
- Plate up to 15 mm, about 2 m wide
- Drive
- 2 × 250 kW induction motors, 2 drives
- Gear ratio
- 1:10
- Control
- Industrial PC + CODESYS Control RTE
- Fieldbus
- EtherCAT, 250 µs cycle
- Master axis
- Line encoder (real axis)
- Line speed
- 10–80 m/min
- Cut length
- 200 mm – 10 m
- Length tolerance
- ±0.5 mm
- Commissioning
- 2025, new machine
- Drives
- Control Techniques Unidrive M701
- Motors
- Leroy-Somer CPLS
- Maximum cutting rate
- 90 cuts/min
The starting problem
Cutting 15 mm thick, 2 m wide plate requires very high knife torque at the moment of the cut. This torque is split between two motors on one mechanism; they have to turn the same drum without fighting each other, sharing the same torque. If one motor gets ahead, the other brakes it, the load piles onto one motor and the mechanism is stressed.
Because the line never stops, the knife must match the plate speed at the moment of the cut; otherwise it pulls or pushes the plate, the cut face is damaged and the length drifts. Cut length varies from 200 mm to 10 m: for short lengths the knife speeds up and slows down every revolution, for long lengths it waits between cuts. At every length the cut must stay within ±0.5 mm.
ONX Control's scope
- Control architecture: CODESYS Control RTE on an industrial PC with a 250 µs EtherCAT cycle
- Two 250 kW induction motors turning one knife mechanism in sync: current loops synchronised over EtherCAT
- Electronic cam on the line encoder: knife at plate speed in the cut zone, positioning for the next cut outside it
- Motion profile calculated for cut lengths from 200 mm to 10 m
- Commissioning as a new machine in 2025
The product's path through the line
-
1
Line encoder
The plate speed and position are measured by the line encoder; this encoder is the knife's master axis.
-
2
Cut length
The operator enters the cut length; the control calculates the knife's one-revolution motion profile for it.
-
3
Sync zone
The knife enters the cut zone at plate speed and cuts without stopping the line.
-
4
Correction zone
After the cut, the knife speeds up, slows down or waits so that it arrives exactly at the next cut point.
-
5
Torque sharing
Two motors turn the same drum; the current loops of both drives run in the same EtherCAT cycle.
-
6
Measurement
The length of the product leaving the line is measured by hand; tolerance ±0.5 mm.
Control architecture
All motion runs in CODESYS Control RTE on an industrial PC with a 250 µs EtherCAT cycle. The knife's master axis is not virtual but the line encoder: the knife moves with the real speed and position of the plate, and when the line speed changes the cam profile scales in the same ratio.
The knife drum is driven through a 1:10 reduction by two 250 kW Leroy-Somer CPLS induction motors, each with its own Control Techniques Unidrive M701 drive. Because the current loops of both drives run in sync over EtherCAT, the two motors turn the drum as a single drive.
CODESYS Control RTE
Real-time control on the industrial PC with a 250 µs EtherCAT cycle: encoder tracking, electronic cam and synchronisation of both drives.
2 × Unidrive M701 + Leroy-Somer CPLS
Two 250 kW CPLS induction motors and two Control Techniques Unidrive M701 drives turning one knife drum together through a 1:10 reduction; current loops synchronised over EtherCAT.
Line encoder
The real encoder that measures plate speed and position and serves as the knife's master axis.
Operator interface
Cut length and line data; the motion profile is recalculated when the length changes.
Axis layout
| Section | Axes | Task |
|---|---|---|
| Knife drum drive | 2 | Two 250 kW induction motors turn the same mechanism. |
| Total | 2 |
The master axis is the line encoder (not a virtual axis); the knife is coupled to it by an electronic cam.
Software
The knife motion is an electronic cam on the encoder. The cam is calculated from the entered cut length: in the cut zone the knife's peripheral speed equals the plate speed; outside it, the knife speeds up, slows down or waits so that it reaches the next cut point on time. If the cut length is shorter than the knife circumference the knife speeds up in the correction zone; if it is longer, it slows down or stops.
Because two motors turn the same mechanism, the current loops of both drives run in sync over EtherCAT; the motors share the torque without working against each other. All of this calculation and synchronisation runs in the 250 µs EtherCAT cycle.
Commissioning
The machine was commissioned as a new machine in 2025. The length tolerance is verified by measuring products leaving the line by hand.
Results and their sources
| Indicator | Value | Source / measurement condition |
|---|---|---|
| Cut length tolerance | ±0.5 mm | ONX field measurement: products leaving the line are measured by hand. |
| Line speed | 10–80 m/min | ONX field data. |
| Cut length range | 200 mm – 10 m | ONX field data. |
| Material | Plate up to 15 mm, about 2 m wide | Project scope. |
| Drive | 2 × 250 kW Leroy-Somer CPLS, 2 × Unidrive M701, one knife | Project scope: current loops synchronised over EtherCAT. |
| EtherCAT cycle | 250 µs | CODESYS Control RTE task cycle. |
| Maximum cutting rate | 90 cuts/min | ONX field data. |
Limits of this page
- The tolerance is verified by measuring products leaving the line by hand; it is not data from an automatic measuring system.
- Line speed and cut length are the limits of the range; they do not mean every speed and length combination is used at the same time.
- The customer is not named. Technical visits or reference calls are arranged with the customer's consent.
Field videos
Frequently asked questions
Why does this rotary shear use two motors?
Cutting 15 mm, 2 m wide plate needs very high knife torque at the moment of the cut; this torque was split between two 250 kW induction motors. Because both turn the same drum, the drives' current loops run in sync over EtherCAT and the motors share the torque without working against each other.
How does a single-knife rotary shear cut from 200 mm to 10 m?
The knife motion is an electronic cam calculated from the cut length. In the cut zone the knife runs at plate speed; for the rest of the revolution it speeds up for short lengths, or slows down or waits between cuts for long lengths. That way one knife covers a wide length range.
Why is the master axis an encoder rather than a virtual axis?
The plate moves at the line's own speed, and the knife has to move with the plate's real position. So the master axis is the line encoder: when the line speed changes, the cam profile scales in the same ratio and the cut point does not drift.
Let's talk about your rotary shear or plate line
Share your material thickness and width, line speed, cut length range and existing mechanics; we will come back with a drive, control architecture and commissioning proposal.