The application of Lenze product automation control system on wallpaper printing machine

1 Introduction

Wallpaper is a very widely used indoor wall decoration material in the market, which is more and more favored by people for its rich color, strong texture, rich patterns, green environmental protection, and noble and elegant decorative effects. Wallpaper is a kind of high-tech products with the concept of green environmental protection, pay attention to environmental protection, use a variety of materials, with different artistic effects, consumers can choose their favorite styles according to personal preferences. With the continuous development of China's economy and society, and the continuous improvement of people's living standards, the use of wallpaper is becoming more and more extensive, and the amount of use is also increasing, and the wallpaper market is extremely hot.

2. The equipment structure and process of the wallpaper printing machine

The printing of wallpaper is mainly divided into two categories: gravure printing and rotary screen printing, and the two processes have their own merits. Gravure wallpaper is characterized by uniform inking, strong sense of hierarchy and high printing accuracy; Rotary screen printing is characterized by a large amount of sizing, which prints PVC slurries of different colors and formulas onto the paper base, and then foams them in the oven to make these slurries foam into products with different heights, strong three-dimensional sense and soft feel. At present, the gravure printing machine or rotary screen printing machine on the market can no longer meet the production needs, and it has begun to be gradually replaced by the increasingly mature rotary screen gravure integrated wallpaper printing machine.

The process of rotary screen gravure integrated wallpaper printing machine equipment is roughly as follows: double-station unwinding→ ironing mechanism→ printing group unit (rotary screen and gravure), → (bedroom oven →embossing machine) or double-station winding, as shown in Figure 1.

The application of Lenze product automation control system on wallpaper printing machine

Note: At present, the round and concave integrated wallpaper printing machine on the market is generally in the case of an embossing machine, and there will no longer be a double-station winding behind it, but it will be replaced by a large roll or a small roll; In the absence of embossing machines, there will be double-station winding, because larger printing factories generally have a separate embossing production line, and smaller printing factories will install embossing machines on the wallpaper production line.

1. Double-station unwinding: It is composed of a double-station unwinding rack and an input traction part, and the unwinding shaft adopts an air expansion shaft and a magnetic particle brake, equipped with magnetic particle tension detection and tension controller, which controls the unwinding tension and has the function of non-stop splicing.

2. Ironing mechanism: It is composed of three internal hollow steel rollers filled with hot grease, and the diameter of these three steel rollers has a certain difference, and its main function is to press the flat roller tightly under the action of tension, and make the paper smooth under the thermal action of boiling oil.

3. Printing group unit: The printing group unit includes gravure roller, rotary screen roller, vertical oven and cold water roller. Gravure rollers are generally carved on steel rollers by laser engraving, and gravure printing is a direct printing method that imprints the ink contained in the gravure pits directly onto the substrate. Rotary screen is made of nickel metal, also known as nickel mesh, hexagonal mesh, rotary screen printing is a printing method that uses a scraper to make the color paste in the rotary screen printed onto the fabric under the pressure drive. A vertical oven consists of an oven body, an axial fan and a burner. When the natural gas enters the burner, the air in the oven box will be heated, and under the action of the axial fan, the hot air will be evenly blown in the vertical oven, so that the wallpaper will be dried very evenly. The inside of the cold water roller filled with circulating condensate is a hollow steel roller, which is used to quickly cool down the wallpaper dried in the vertical oven to enter the next color group printing.

4. Horizontal oven: its composition is the same as that of vertical oven, but it is a little shorter and longer than vertical oven, and its function is for rotary screen printing foaming.

5. Embossing machine: It is made of embossing roller and four-cylinder cooling mechanism, and its function is to make the wallpaper printing pattern foam at high temperature in the horizontal baking, which can form a three-dimensional wallpaper with uneven patterns. The function of the embossing machine is to use the embossing roller to press on the convex pattern to make it more three-dimensional.

6. Double-station winding: The winding department adopts a double-station rotary receiving rack, air expansion shaft rewinding, equipped with a pendulum roller type full closed-loop tension control system to control the winding tension, and the tension adjustment is set by a precision pressure regulator and performed by a low-friction cylinder.

Wallpaper production process:

Base paper is sent→ coated→ dried (gelatinized→), cooled→ printing, → → softened by heating→ embossed→ cooled→ trimming→ storage, inspection→ coiling→ packing → warehousing.

3 Lenze Solution

Lenze proposes an automatic control system solution with the central motion controller 3200C as the core. The perfect combination of a separate HMI P300 controller at the display level and I/O 1000 and 3200C at the control level performs all logic control. The innovative i700 servo drive with its compactness and high flexibility and the compact, dynamically responsive MCS and MCA motors with pluggable link design on the drive level enable high-precision motion control functions to be implemented more reliably.

The 3200C motion control system based on the motion controller can provide more perfect control for more complex and precise equipment, and can improve the control performance of the equipment to a large extent. The control system adopts the on-board high-performance real-time bus system EtherCAT, whose protocol processing is completely carried out in hardware, and an ultra-high-speed control loop can be formed through the bus, which makes the network performance reach a new level and realizes the control concept that the traditional fieldbus system cannot reach. The network topology of rotary screen gravure integrated wallpaper printing machine is shown in Figure 2 below.

The system takes the 3200C motion controller as the core, including a number of drive i700, a 9400, a number of MCS motors, an MCA motor and four asynchronous motors, among which the MCS and MCA motors that follow the virtual axis to do position synchronization respectively realize rotary screen printing, gravure printing, embossing and cold water roll tension adjustment, follow the virtual axis to do speed synchronization MCS motor to achieve full closed-loop tension control of the ironing machine, and use the virtual axis as the speed source. Four independently controlled asynchronous motors are used for rewinding and unwinding.

Thanks to the excellent performance of the Lenze control system and the perfect cooperation with the customer's machinery, the rotary screen gravure integrated wallpaper printing machine can produce gravure up to 100 m/min, rotary screen up to 80 m/min, and the overprint accuracy can reach 0.15 mm without registration.

4 Main features implemented

(1) The use of virtual electronic axis control, to achieve multi-axis position synchronous printing: the use of virtual axis as the main axis, so that the other printing axes are synchronized with the virtual axis, the use of virtual axis can reduce interference and fluctuations, improve the printing accuracy.

(2) Double-station rewinding and unwinding and non-stop receiving: The rewinding and unwinding controlled by L_TT1P_WinderDancerCtrlHigh only need to type in the key parameters such as the initial rewinding diameter, the left and right limits of the pendulum rod, etc., and the automatic rewinding and unwinding control based on the initial rewinding and unwinding can be easily realized, which is simple to operate and easy to understand. The winding is also equipped with a taper tension function, which allows for perfect control of the inner tightening and outer loosening without the need for additional equipment.

The double-station unwinding and rewinding at any speed do not stop receiving materials, which avoids the loss of consumables and production delays caused by downtime, saves production costs and improves production efficiency.

(3) Closed-loop tension control of intake and traction, tension monitoring and indirect control of panchromatic group:

The degree of control of the tension of the wallpaper machine is directly related to the printing accuracy of the wallpaper, so the key to wallpaper printing is the control of the tension. In the ironing machine and the one-color printing unit, a tension sensor is installed between each two adjacent printing units to control or monitor the current tension status of the unit unit in real time. The servo axis of the ironing machine needs to be fully closed-loop tension control, and the feeding material is accurately controlled, and the tension is controlled at about 2% of the set value. Due to the adjustment of tension between each adjacent two printing units, the linear speed is changed slightly by adjusting the electronic gear of the servo shaft of the cold water roller, and the tension between the printing units is changed indirectly and slowly to achieve the balance of tension.

(4) Pre-flowering and flower-chasing function:

The pre-alignment function, that is, the function of retaining the current position of each printing axis at a certain time in the original production printing. Before the next printing, move each printing axis to the position that it was remembered for the last printing. The introduction of the pre-flowering function greatly reduces the waste of the machine in the printing preparation stage, saving a lot of raw materials for the enterprise.

The tracing function is to adjust the phase difference between two-color printing or certain color printing axes to achieve high-precision printing.

(5) Independent embossing function

The embossed wallpaper is more three-dimensional and realistic. However, not every kind of wallpaper is suitable for embossing, and wallpaper also has certain temperature requirements before embossing. In this case, the independent embossing system comes into being. When embossing is required, the electrical embossing system is used, and when embossing is not required, the embossing system is removed. At the same time, the embossing system can also be pre-aligned and traced to ensure maximum savings in raw materials.

5 Technical key points

1) i700 has the characteristics of small installation size, power supply through DC busbar, automatic download of parameters/firmware through the control system, pluggable connection technology, etc., which can save a lot of installation space for customers, improve the efficiency of power supply, more easily realize parameter modification and firmware upgrade, and bring more convenience to replacement and maintenance.

2) The control system is equipped with EtherCAT on board, which makes the performance of the control network reach a new height and greatly improves the performance of the equipment.

3) Equipped with Intel® Atom™ 1.6 GHz high-performance 3231C processor, battery-free and fanless design, ensuring that the device does not need maintenance. In addition, the device is designed with a removable memory card for easy replacement.

4) PLC Designer-based L_TT1A_TechnologyModules develop special function blocks for specific applications, such as Dancer-Controlled Winder technology module or Tension-Controlled Winder technology module for rewinding and unwinding module）； For cam control, there is an electronic cam technology module (FlexCAM technology module), etc., Lenze has integrated many years of industry application experience into it, making specific control more professional, and at the same time easier to operate, greatly reducing the amount of programming work.

5) Use the technical module Application Template PackML template programming based on PLC Designer programming software.

6) It takes 20% of the time to complete 80% of the work, which saves a lot of time for the customer's machine to be listed.

6 Outlook

In the early stage of development, the wallpaper printing machine was a gravure mechanical through-axis, with low printing output and poor accuracy. Later, it developed into gravure electronic axis and rotary screen electronic axis, although the accuracy and output have been improved, but the products produced are still relatively single, and the current emerging rotary screen gravure integrated wallpaper printing machine has overcome all the above shortcomings, not only high production efficiency, high product precision, and has made a great breakthrough in the process, which can realize rotary screen priming, gravure overprinting, and can develop more beautiful products. It is believed that with the vigorous development of the wallpaper market and the further improvement of people's requirements for wallpaper quality, the rotary screen gravure integrated wallpaper printing machine is bound to become the leader of the industry.

The war of Industry 4.0 has been ignited, and industrial automation control is the core, I believe that Lenze will create an automated control system with better performance with its excellent motion controller, perfect drive, and unparalleled reducer, and contribute to the fourth industrial revolution.

The application of Lenze product automation control system on wallpaper printing machine

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