LM-250/500 laboratory rolling mills

Construction of LM-250/500 rubber and polymer rolling mills.

• The working element of the rolling mill are two heated and cooled rollers, covered with a layer of technical chromium, which gives them the required hardness and smoothness of the surface.

• The distance between the rolls is infinitely adjustable in the range of 0.2 mm to 10 mm with an accuracy of 0.1 mm.

• The width of the gap between the rolls is constantly measured during rolling. The digital control system dynamically controls the parallelism of the rolls relative to each other and corrects any deviations from the set value.

• The width of the gap between the rolls during the operation of the rolling mill is constantly corrected as a function of changes in the temperature of the rolls Rollers increase in diameter during heating due to the phenomenon of thermal expansion This phenomenon leads to a change in the width of the gap between the rolls and is noticeable when the gap is set to values below 1 The digital control system corrects these changes, ensuring that the gap has the set value regardless of changes in the temperature of the rolls during heating and cooling.

The main drive of the rolling mill rolls.

The rolling mill is powered by two modern AC motors made in 120 Hz technology. These motors provide power to the rollers. In the case of a rolling mill equipped with rolls with a diameter of 250 mm, the maximum torque per one roller is 4200 Nm. The rolling mill will not stop even when working with extremely demanding materials. Such motors have an increased range rotational speed control, especially in the range of low rotational speeds and ensure a constant maximum torque in the entire speed range In addition, such motors are practically maintenance-free and their operating costs are low An important element of the drive are two cooperating frequency converters [inverters] The inverter allows you to independently control the rotational speed and their torque We use motors and inverters from renowned manufacturers An optional module for measuring the energy consumed and controlling its quality allows you to control the costs and quality of the energy consumed on an ongoing basis, which increases research capabilities of rolling mills.

The main drive of the mechanism for setting the working gap of the rolling mill

The unique electric mechanism for adjusting the gap between the rolls automatically controls the mutual parallelism of the rolls during operation Possibility of quick adjustment of the gap between the rolls and its continuous control during the rolling process determine the efficiency of the process and save material forces during rolling.

The working gap adjustment mechanism is based on precise ball screws
At the heart of the roll gap control system is B&R's [Bernecker and Rainer] ACOPOS P3, a highly efficient and precise dual-axis servo drive that sets new standards in motion control. This servo drive is one of the most powerful servo drives with integrated safety features on the market. sampling time of only 50 µs for the entire controller cascade.The parameters of this drive and the integrated safety system allow you to meet the requirements of the safety standard for rolling mills.

The mechanism for regulating the temperature of the rolls of the LM-250/500 rolling mill.

LM-250/500 rolling mills can be equipped with one of two heating and cooling systems:

• Water system enabling operation up to a maximum temperature of 130°C.

• Oil system allowing operation up to a maximum temperature of 250°C.

As an option, it is possible to use independent oil or water heating and cooling systems for each roller. This solution allows for independent temperature control of each roller.

Temperature measurement is carried out by means of 6 precise temperature transducers, arranged in such a way as to enable control along and around the perimeter for each of the three heating zones of the roller. The heaters and the heating and cooling systems are simultaneously regulated by a digital PID controller (proportional-integral-derivative) Such a solution allows you to maintain the set temperature with high accuracy and avoid the so-called overshoots, i.e. uncontrolled increases or decreases in temperature A digital temperature controller developed by our automation department supervises the operation of all zones simultaneously, taking into account their mutual influence, thanks to which the temperature is stable and consistent with the set values and the measurement is reliable
In order to ensure high reliability of the temperature measurement system, the sensors are doubled [Redundant system], in practice it means that each roller is equipped with 6 temperature sensors. Additionally, rotating joints transmitting electrical signals to the roller are equipped with spare contacts. Such a system is reliable and reduces costs and time possible repair.

Mechanism of automatic mixing of the rolled mix.

When it is necessary to roll mixtures requiring high temperatures, the operator's work becomes less comfortable, because it requires the use of thick and uncomfortable gloves to protect the hands. To avoid your inconvenience, the rolling mill can be equipped with an automatic mixing machine. in such a way that it wraps the edge of the rolled mix and thus mixes it. The mixer's work cycle is freely programmable from the operator's touch screen. An unused mixer is parked outside the rolling mill's operating area.

Roller safety system

Growing safety requirements for rolling mills and calenders mean that cylinder shifting systems must comply with the applicable standards and ensure high precision and reliability of operation. rolling mill and operator [safety standard EN 1417 and later requires that the speed of emergency opening of the rolls for a minimum distance of 50 mm does not exceed 5 seconds, moreover, the rolls must stop turning by a maximum of 90 degrees. In addition, the force measurement enables constant control of the clamping force of the rolls and protects the machine from overload.
The safety system can be activated by hand, head or knee if necessary. The system complies with and exceeds current requirements.When the rolling mill safety system is activated, the automatic rollers brake practically on the spot and move away from each other within 50 mm in no more than 5 seconds.

To ensure the required work safety, the rolling mill is equipped with two UPS (Uninterruptible Power Supply) systems.

The first and main DC UPS emergency power system is designed for continuous power supply, independent of mains voltage loss, to the internal power bus of the B&R's ACOPOS P3 two-axis servo drive, which is a key element of the rolling mill's safety system, as it ensures safe roll-off of the rolls for a distance of 50 mm in in the event of activation of the security systems, the UPS is equipped with a system for continuous monitoring of battery voltage and temperature. In the event of irregularities in the UPS system, the security system will not allow the device to start or will turn it off in emergency mode. The second UPS is used to power the digital control system of the rolling mill. after a power failure, ensuring reliable operation of safety systems and their control by the operator.
B&R's [Bernecker and Rainer] safety system is integrated with the machine's control system and communicates with it via an extremely fast real-time bus.

Digital rolling mill control system.

The operation of the rolling mill is monitored by a PLC computer system. It is possible to control all parameters of the rolling mill operation with a color touch panel. It is also possible to visualize and save most of the operating parameters and export them to spreadsheet files. Our software allows you to steer, control and manage research processes Continuous control of rolling mill parameters such as: temperature, friction, rotation, torque, force, energy consumption, allow you to have control over the process and the rolling mill Additionally, you can add the ability to save parameters to the database for later use analysis and archiving, on-line display of charts and work in the company network and even global. Thanks to our software, we can conduct research and transmit the process and video image via Ethernet to any place for computers, tablets, etc. Our software can be adapted to the expectations of our customers.The process can be controlled from the touch screen on the device console or over the Ethernet network.

Laboratory extruders have such a durable and reliable construction and a high level of safety that they can be used in industry

Security system:

1. Safety system in accordance with the applicable EN-1417 standard - Yes

2. Emergency braking - Yes < 60 degrees

3. Roller emergency extension - 50 [mm]

4. Roller emergency extension time - < 5 [s]

5. Mechanical shields with safety sensors - Yes

6. Safety switches - manual buttons - 2 [option 4]

7. Safety switches - knee buttons - 1 [option 2]

8. Back-up power supply for safety systems - UPS Yes - maintains the operation of safety systems - enables emergency rolling of the rollers after a power failure

9. Safety switches for head or hand - Yes

10. Electronic overload protection - Yes

11. Short-circuit protection - Yes

12. Shock protection - Yes

13. Main switch - Yes

Important usable features:

1. High performance parameters [torque, force between rolls, precision of operation]

2. Built-in heating and cooling system adapted to the user's needs.

3. Precision high temperature spherical roller bearings.

4. Precise measurement of parameters [torque, force, temperature]

5. High safety of use even in the event of a power failure

6. Optional module for measuring consumed energy and parameters of the power supply network

7. High energy efficiency

8. High component durability

9. Ethernet integration

10. Adapted to Industry 4.0