and high-tech

Hot Coil Marking Unit

In its program, Production and Engineering Company ENCE GmbH highlights the most significant metallurgical equipment; this equipment complies with the highest international quality standards and may be offered to customers at competitive prices.

EXAMPLE Hot Coil Marking Unit

ENCE GmbH engineering (company) offers a number of accessories and component parts for cold rolling of coiled steel as well as treatment lines for coiled steel (steel strip hot galvanizing line, lacquer or polymeric coating line, steel strip pickling line, slitting and shearing lines for coiled steel).

As an example, ENCE GmbH company offers a variant of supplying a marking unit for hot coil marking.

Robotic Marking Unit for Dotted Marking on Hot Coils
1. Introduction

In this example the ENCE GmbH company offers a marking unit for dotted marking. The unit is designed for hot coil marking when a coil stops. This unit is normally employed when marking is assigned a short period of time. The time spent on the stop for marking may be considerably reduced when using a marking machine with dotted marking. When enough time is available a machine with one gun may be employed. The principal difference (as compared with the unit for dotted marking) is the marking design.

The time of marking cycle always depends on the coil dimensions and the number of characters.

The rest of the accessories such as a robot, safeguard, electric cabinet, paint feeding unit, the type of the head etc. are the same for the both types of the machines.

The coil is marked circumferentially with three lines and one line on the coil butt.

Marking by the robot is fully automatic

The hot coil marking unit is located near the indexing feeder.

Marking is alphanumeric and is carried out by a head for dotted marking with 7 guns directly on the coil surface to be marked.

The system of paint marking is based on the process of marking with seven pneumatic paint-dispersing guns that operate independently.

A special design of the nozzles for the dispersing guns and a set for automated routine cleaning provide constant due operation of the nozzles with minimum maintenance.

Standard accessories for the hot coil marking unit:

  • Industrial robot.
  • Marking head for dotted marking with 7 nozzles.
  • Combined electric cabinet for the principal unit and robot with PLC to control the unit.
  • Operator’s terminal with a display and a keyboard (the system is the man-machine interface).
  • Maintenance and repair board.
  • Combined paint and air feeding system.

The marking cycle is fully automatic in all cases. The data to be marked on the coil come from the plant’s controlling computerized system or typed from the operator’s terminal.

2. Description of hot coil marking unit

2.1. Coil Specifications.

Product: coils
Number of conveyors: 1
Location of the unit: suggested: to the right of the conveyor coil system (when
looking in the direction of travel, the location may be changed).
Surface temperature of the hot coil: min. 80°C — max. 350°C
Coil orientation: vertical (central opening upwards),
coil axle – in the vertical position.
Marked surface: clean and dry
Coil outer diameter: to be confirmed: min. 1200 mm – max 2100 mm
Coil inner diameter: min. 800 mm – max. 900 mm
Coil width: min. 700 mm – max. 1550 mm
Strip thickness: min. 1.2 mm – 16 mm
Coil weight: presumedly 38 tons
Coil end position: to be defined
Marking and marking position
on the coil butt:
1 line is marked on the bend (curve) on the coil butt with
characters approx. 70 mm to 120 mm high, total of 15
characters. The character height depends on the space (place)
available on the coil butt. Details of the marking position and
design to be defined upon submitting your scheme.
Marking and marking position on the surface: 3 lines on the coil circumference and transversally (crosswise /
conversely) to the coil axle, with typical characters approx. 70
тmm to 100 mm high, total of 35 characters. Details of the
marking position and design to be defined upon submitting
your scheme.
Coil packing band 1 band along the circumference shall be placed in the middle of
the coil width. To the extent possible, the marking unit shall
avoid (reject) applying marking on the bands, the allowed
positioning precision will be not observed for the band/strap. In
case the coils are not too wide and when there is a certain
number of characters marking on the band may become
unavoidable due to a limited space/place for marking. Then we
may consider/apply smaller characters for marking. The
character height is adjusted automatically.
Band width: 32 mm
Transportation system: presumedly: chain-linked conveyor.
Distance between coils on the conveyor: presumedly: 2100 mm (center to center).
Positioning field in the direction of travel: about: ± 15 mm
Positioning field against the direction of travel: about: ± 5 mm
Telescoping allowance: up to 300 mm (when telescoping is
large no marking is carried out).
Environment temperature: approx.: min. 10°C – max. 45°C
Relative humidity: unknown

Coil dimensions (coil outer diameter and width), marking data and the process of banding are communicated to the marking machine in advance before the signal to «start marking» is sent.

If there is a stock / accumulation of hot coils behind the marking unit the customer shall install a heat shield and required accessories to prevent thermal radiation to the marking machine.

2.2. Hot Coils Marking Unit Specifications.

2.2.1. Marking unit data.

Character height: approx. 70 mm to 120 mm dependent on the space / place
available for marking on the coil.
Character width: approx. 2/3 of the character height
(i.e. height = 90 mm, then width = 60 mm).
Number of characters: 1 line on the disc side (along a curved line),
15 characters 3 lines along the circumference, 35 characters
Allowed characters: 0…..9, A….Z, standard (readable) signs / characters (such as
=, +, -, х, / etc. and chosen numbers of program characters.
Total weight of equipment: approx. 3.2 ton
Marking unit approx. 2200 kg
Electric cabinet and control boards 1000 kg.

Marking characters / examples

Duration of hot coil dotted marking cycle with a robotic unit
Coil detection cycle (automated calculation of outer diameter) [time
depends on the actual outer diameter of the coil]
8 to 12 s 12 s
Advancement to the coil butt (along a curved line) 3 s 3 s
Coil butt side detection and search for telescoping (calculation of the coil
position in the direction of travel) [time depends on the actual coil width]
10 to 12 s 12 s
Coil butt marking (along a curved line) 1 line 15 characters 1 х 2 s 2 s
Advancement to the position for coil surface marking to the first line 3 s 3 s
3-line marking along the circumference 15 characters in the line 3 х 2 s 6 s
Return to home position 2 s 2 s
Marking cycle duration 35-40 s
«Marking over» signal and «Release indexing feeder» signal will be sent to the main computing machine.
The coil may be advanced to the next position, and a new coil may be fed to the marking unit.
The time period when the next coil is fed to the marking
position is used to clean the paint dispersing gun (marking head):
Advancement to the cleaning station 1 s 1 s
Marking head cleaning with brushes
(water then is sprayed from the nozzles for cleaning)
5 s 5 s
Advancement back to home position (standby) 1 s 1 s

2.2.2. Requirements to the Supply of the Robotized Marking Unit for Hot Coil Marking.

Electric power supply
Mains voltage: 2Х380V ± 10%, 50Hz ± 1%
Voltage for solenoid valve: 24 V, direct current
Rated capacity: approx. 12 kVA
Voltage on PLC I/O: 24 V, direct current
Supply voltage of PLC: 24 V, direct current
24 В, постоянный ток
Compressed air supply, provided by the Customer
Compressed air: dried, clean, with no particles
Pressure: 4 to 6 bar
Dew point: below environment temperature
Oil content: < 1 mg/m3

Following the compressed air connection point a pneumatic service unit is installed which comprises a pressure regulator, a filtering element, a pressure regulation separator and a water separator.

2.2.3. Utilities for a Robotized Marking Unit for Hot Coil Marking

Water for nozzle cleaning, provided by the Customer
Clean water: filtered and treated water from the workshop supply network;
рН 6.5 to 8 (max. 30°C to 40°C in the connection point. Tap
water is recommended. Following the connection point a
filtering element shall be included in the marking unit.
Pressure: 3~4 bar at the connection point
Paint: water-based, environment-friendly
Paint is ready for use, doesn’t require dissolving.
Store at a temperature between +5°C and 30°C.

2.2.4. Power Consumption of the Robotized Marking. Unit for Hot Coil Marking:

Power supply
Rated capacity: approx. 12 kVA
Compressed air
Consumption: max. 0.2 Nm³ during marking
max. 0.005 Nm³/s during standstill
Washout unit: max. 0.005 Nm³/s
Consumption (max.): max. 0,02 Nm³/s during marking
Water for water-based paint
Consumption max. 70 ml for the cleaning process
For a stop: 4 liters per hour
Consumption (max.) 0.3 l/s
Consumption approx. 7000 characters / kg
approx. 10000 characters / liter

2.3. Functions of the Marking Unit and Marking Cycle.

The basis of the marking unit is an industrial robot. The marking head operation is based on a technology using seven nozzles that are installed on the axe. The robot advances the marking head around the coil dependent of the marking position on the coil.

The robot and the marking head construction are designed for operation in severe environments: on rolling mills and at steel works.

Marking by applying three lines on the coil circumferential surface and marking by applying one curved line at the disk

Marking data are automatically communicated to the controller of the marking unit via the host computer or through the man-machine interface on the operator’s board. The controller saves this data.

The unit is advanced to the product to be marked by means of external signals «Coil in marking position» and «Start marking». The unit is stopped by a contact switch. Then the robot starts calculating the coil outer diameter and position for the curved marking. The robot takes the initial position for marking and, when the unit is at the required distance from the product the robot starts marking. The robot advances the marking head along each marking line to be applied. When the last marking is applied on the product the unit takes the initial position and awaits the next cycle to start. During the marking cycle the marking unit PLC sends a signal to the host PLC: «to block the movable traverse». During the marking cycle the traverse blocking is the end user’s responsibility.

When the marking cycle is over the marking head starts a fully automatic cleaning cycle. When a water-based paint is used (for hot application, for example, on hot coils), the flushing liquid then is water (that would be a solvent in cold application). Flushing cycles may be programmed to optimize the flushing liquid consumption. The flushing process helps preventing nozzles from being clogged. It increases reliability of the marking unit and considerably reduces the amount of maintenance works. During the cleaning cycle the robot transfers the marking head along the brushes to clean the inner surface, too. Thus high reliability and uninterrupted operation is secured for the entire marking equipment.

2.4 Hot Coil Marking Unit Working Modes

2.4.1 Setup Mode

In the setup mode checkup and process service operations are carried out. Each robot’s movement may be set (actuated) with a joystick on the pendant robot setup push-button panel. Other functions (e.g. nozzle checkup) may be actuated by pressing buttons on the local control board.

2.4.2 The Unit’s Semi-Automatic Mode of Hot Coil Marking

The unit is controlled from the operator’s control board.

The marking text is typed via the touch pad. The marking is carried out automatically and triggered by either parallel signal from the control system of the work process or an operator’s signal from the man-machine interface.

2.4.3 The Unit’s Automatic Mode for Hot Coil Marking

The marking text is sent via the interface from the central control system, the marking process is triggered automatically.

2.5. Overview of the Coil Marking Unit Assembly

1 pc. Standard dotted type marking system. It is an automated machine with a controller for fully automatic product marking.

Each component is completely assembled, connected by cables and piping to contact strips or power terminal. Painting and corrosion protection comply with European standards.

The hot coil marking unit comprises the following principal components:

1 pc. robot
1 pc. robot software to detect collisions and loads
1 pc. robot support plate
1 pc. dotted type marking head with seven nozzles located along the robot’s axe
1 pc. pneumatic/mechanical measuring device
1 pc. paint/solvent feeder with a filter, a paint pump, a lifting device
for paint containers, a mixer and hoses to the marking head
1 pc. pneumatic control group with a service block
1 pc. safeguard around the marking robot with a door and a safety lock
1 set. of electric components located on the machine
1 set. of the principal control (distribution) cabinet with PLC
1 set. of the robot control cabinet located near the unit
1 set. of the combined control: principal control cabinet / robot control cabinet,
to be installed in the ventilated room (cable length limited to 20 to 30 m)
1 pc. local control cabinet located near the unit for its maintenance and repair
1 pc. interface to communicate with a customer through the network
1 pc. Windows man-machine interface with PC and 19″ screen
1 pc. cooling ventilator with a safeguard to cool the robot
1 set. of anchor bolts
1 butch. of paint for hot marking for commissioning (2 containers, 60 kg)

2.5.1. Electric Components Located on the Machine for Automated Coil Marking.

1 set of electric equipment including end switches, proximity switches, terminal blocks and wiring from the unit components to the control cabinet located near the unit.

2.5.2. Local Controller of the Automated Coil Marking Unit with a «Robot Teach Control Pendant» (for Maintenance and Repair).

The «robot teach control pendant» allows carrying out all operations of maintenance and repair.

The screen provides information on the status of the unit and peripheral hardware. Local controllers of the unit with a «robot teach control pendant» represent the state-of-art industrial standard.

2.5.3. Principal Control Cabinet and Robot Control Cabinet (the location to be discussed).

1 set of a combined control cabinet located preferably in a ventilated room (cable length is limited to 30 m – option).

— Standard control cabinet with an «adjustment pendant» for improved control of the robotic marking system.

— Robotic control device

1 pc. PLC,
1 communication interface to Level 2.

The software provides a complete control of the equipment; the software includes operation information, i.e. data on marking, unit status and fault messages.

The combined control cabinet (principal control cabinet / robot control cabinet).

2.5.4. The cabinet for the «Adjustment Pendant» of the Robotic System.

1 pc. cabinet to protect the liquid-crystal panel (teach pendant) equipped with a heating system and a thermostat.

2.5.5. Man-Machine Interface Installed on the Operator’s Panel of the Control board.

The man-machine interface is Windows with a PC, 19” screen and software that provides a complete control over the equipment. The operator’s board will show information such as marking data, the unit status and fault messages.

2.5.6. Special Tools.

Not required.

2.5.7. Connection Point for the Hot Coil Marking Unit.

The connection point of the marking unit must be located at the distance of 1 m from the paint cabinet.

External piping of the connection point shall be provided by the customer. Piping inside the connection point shall be provided by the ENCE GmbH company.

The final location of the connection point and the connector dimensions of the hot coil marking unit will be approved upon order placement during development and a discussion meeting.

2.5.8. Paint Cabinet Located Close to the Coil Marking Unit.

One paint cabinet is located on the site close to the coil marking unit.

2.6. Properties and Advantages of the Coil Marking Unit.

2.6.1. Overview of the Dotted Marking Method.

An example of a marking head with seven nozzles (brass basement plate).

Pic. 1. Top view of the dotted marking head with seven nozzles for hot and cold application.
Upper arrow — The rear end for nozzle adjustment.
Lower arrow — The front end for the nozzle marking, material: stainless steel.

Pic. 2. Bottom view of the marking head.
Upper arrow  — Joints for the adjustable valve.
Middle arrow  — Basement plate.
Lower arrow  — Only one screw to remove a nozzle from the basement plate.

Marking head method is based on standard paint spraying nozzles (guns or spraying pulverizers). The nozzles are mounted on the basement plate. In a standard model seven spraying nozzles are collected in one marking head. Solutions with a greater number of spraying guns, e.g. nine spraying guns, may compile (make) графический a customer’s sign or special characters may be higher than seven dots (dashes).

Precisely finished nozzles are designed for long-lasting (continuous) loads and offer precise dotted characters. Characters may be 50 to 200 mm high (150 mm with seven nozzles, 200 mm with 9 nozzles). The dash (dot) dimensions and paint amount are easily regulated on each marking nozzle. Nozzles can be easily replaced in turn during maintenance. There is only one screw to remove on the rear side of the basement plate. It is convenient to replace nozzles one by one within one minute.

2.6.2. Overview of the Marking Unit Nozzle.

Typical marking design on coils.

The nozzle has a flushing course (rinser). In hot marking water is used for flushing. A special design of the nozzle’s inside does not allow the flushing liquid to come into contact with paint. It means that a guaranteed ideal marking design can be obtained immediately after the nozzle rinsing as there is no flushing liquid left in the nozzle and the paint is not influenced by the flushing liquid (paint does not dissolve). It eliminates the necessity to carry out continued (multiple) trial starts before you start working on a coil; therefore, the paint consumption is reduced while the gun is more reliable.

The front end of the nozzle is made of stainless steel.

The nozzle can be easily removed for repair and maintenance. For wear parts there is a set of spare parts for replacement, including a needle, a spring, nozzle of material, seals etc.

2.6.3. Automated Flushing of Nozzles by Venturi Gun.

A Venturi gun is used for the above flushing process. The process is so arranged that upon applying an inscription with paint there opens a Venturi gun and flushes the front end of the nozzle with water-air mixture. As water possesses wetting ability there is some water left in the front end of the nozzle when flushing is over. To prevent the water left from coming from the nozzle onto the coil during the next marking cycle the flushing course is automatically purged with air. Accordingly, no water is left in the front end of the nozzle. → Immediately after flushing the nozzle is ready for the next marking cycle.

2.6.4. Paint/Solvent Feed.

Marking head with seven nozzles is completed with a paint cabinet that provides convenient handling with paint itself and insures continuous paint feed to the nozzle.

Paint feed will be carried out by a lifting device for a paint can with a filter and a pressure regulator. Depending on the type of paint used there may be also installed: a mixer, a circulation pump, auxiliary paint pressure regulators and a level regulator.

When paint is over in the can the operator is required to lower down the paint can (the lifting device). Then the operator can remove the empty paint can and replace it with a new one. The basic advantage is: there is no clogging of the tubes that feed paint because of old dry paint particles. It occurs if no sufficient cleaning of the paint container was done

The paint cabinet dimensions are about 1200 х 2000 х 600 mm (width х height х depth).

Paint will be fed to this cabinet from the main distribution cabinet.
The paint cabinet should be placed in close vicinity to the marking head (~15-20 m) to provide continuous paint supply to the nozzles.

2.6.5. Advantages of Painting Method with a Robotic Hot Coil Marking Unit.

  • Fully automatic system промывки of the marking head flushing considerably reduces maintenance.
  • Standardized painting section for convenient work with painting and cleaning environments.
  • Thanks to the lifting device within the painting section there is no need to lift heavy containers to refill with paint.
  • Modular enginery within the painting section for easier maintenance.
  • Modular enginery of the marking head for easier maintenance and servicing.

Set of Hoses

A set of hoses provides an advantage of all cables and hoses being inside one flexible hose that is specially designed for robots. The flexible hose is placed inside a heat-resistive hose that can withstand temperatures over 1000°C.

Brushes for outer cleaning of the marking head.

One of the advantages is that the marking head is completely cleaned by brushes in the automatic mode. Therefore, the robot advances the marking head along brushes that are installed in the cleaning box. A greater reliability and availability are secured.

Thermal insulation

Thermal insulation of the marking unit possesses a greater resistance against harsh environments in hot workshops. Thermal insulation comprises two plates. One plate is made of a durable material and the second plate is a galvanized sheet that reverberates heat and, on the other hand, protects the heat-resistive plate against mechanical impacts.

Marking head nozzles in the coil marking unit

The following photos show the design of a new marking head for harsh environments at steel plants. You can see as well that the set of hoses and the head are very compact and protected against heat radiation.

Marking with a cleaning station (with a cover open).

«Plug and Play»

The marking unit is completely assembled and integrated / installed before the connection point. It means that certain parameters of the marking unit require setup in-situ (such as the indexing feeder level and coil position). The entire equipment is ready for use after installation and setup, according to «Plug and Play» principle.

3. Scope of delivery for hot coil marking unit:

1    Industrial robot

2    Robot’s basement plate

3    Steel structure / foundation for robot

4    Set of hoses for robot

5    Marking head cover

6    Marking head (seven nozzles)

7    Safeguard around robot

8    Paint feeder

9    Coil detection unit

10   Pneumatic control unit

11   Anchor bolts

12   Heat-protective shield and required accessories to protect the marking unit for coils prepared for marking

13   Intermediate pipe between the connection point and the plant network

14   Machine piping to the connection point

15   Cleaning station

16   Drainage piping under the cleaning box

17   Paint for commissioning

18   Machine-installed components, incl. cables to terminals (connecting screws)

19   Local control board and terminals (connecting screws)

20   Combined principal electric cabinet and robot cabinet (normally installed close to the unit behind the protection shield)

21   Remote panel for the teach pendant

22   Protection for the teach pendant

23   Windows-based man-machine interface with PC, monitor, keyboard and mouse installed on the existing board (control platform)

24   Heater for the painting cabin

25   Robot’s cooling fan

26   Alarm annunciator of status, errors, diagnostics

27   Cabling after the connection point to the marking unit

28   Data cable

Additional Information

Beside hot coil marking units, ENCE GmbH engineering company supplies, through its extensive network of a wide range of component parts, drives and  replacement assemblies for rolling mills and coiled steel treatment lines: