Methods For Identifying Double Layers Or Material Sheets

Double sheet detection is an important process of effective quality control. The role of a reliable double sheet detector is to prevent the occurrence of two or more sheets from entering processing machines in a single instance. Failure of detecting double sheets or double blanks can damage dies and tools. Ultimately, it will result in production downtime and expensive repairs. This is wherein the role of an effective ultrasonic double sheet sensor comes in.

So, How does a sensor work? We’ll shed some light on the workings of these double sheet detectors. It will help you understand the concept in depth.

A] Different Factors Influencing Double Sheet Detection

Double sheet detectors are helpful in monitoring subsequent layers of different materials as they enter different processing machines. Double sheet detector sensors are utilized in applications wherein multiple plates or sheets are processed. The process involves that industries capable of processing labels, using printing machines, or working with folding machines should be able to detect faults with the identification of double layers or material sheets.

Accumulation of material sheets or plates, wrinkles, and creases can make the entire printing process come to a full stop. However, with the help of reliable detection sensors, production errors can be identified early in the stage while saving both time and money in the long run.

We’ll discuss some factors that influence the process of double sheet detection. They are listed below:

• Environmental Factors: Specific environmental factors like humidity, temperature, barometric pressure, and height above the sea level can impact the signal amplitude that is measured by the receiving end of double sheet detectors. Barometric pressure and temperature are the most significantly influential factors. You should take these factors into consideration before choosing the right double sheet detection sensor.
• Characteristics of the Materials: Sound amplitude of a double sheet detector can also be affected by material characteristics. For instance, volume, grammage, recycled content, and homogeneity affect the factor of attenuation in the process of sheet detection. As a sheet or paper features multiple fibers, the accumulation of fibers will differ from one sheet to another. Different parts of the sheet can depict unique attenuation of the sound amplitude in the process of double sheet detection.Factors like weight and grammage also influence attenuation. Higher grammage sheets are capable of attenuating ultrasonic signals to a higher extent. At the same time, paper having a higher volume (paper used in book printing) will have more air between individual fibers, eventually, depicting improved sound absorption.
• Alignment of the Sensor: The right measurement of double sheet detection can be influenced by the alignment of the sensor. It is particularly true when the receiving and emitting units tend to be separate. The center of the transducer serves to be the most sensitive part of any ultrasonic sensor. Therefore, it is important to note that the center of the sound beam is effectively aligned with the receiving transducer’s center.When you ensure the same, it will deliver the assurance of the highest possible amplitude along with the widest range of materials and the measurement of the largest reserves of tolerances.

B]  The Use of Sensor Technology for Detecting Double Sheets

Double sheet detector sensors are available as ultrasonic double sheet sensors. These sensors on a standard machine vision system are placed in front of each other. The role of the first sensor is to function as a transmitter. On the other hand, the second sensor serves the role of a receiver. The material that is expected to be detected goes through both the sensors.

During detection, the transmitter is responsible for sending out an ultrasonic soundwave from one end of the material to the other end. The sound waves will ultimately reach the sheet or paper. The signal goes through the entire sheet. It is eventually weakened as it will reach the receiver on the extreme side. The weakened signal or soundwave reveals that there is a presence of a sheet.

For instance, when a material like paper will flap due to vibrations sent out in the form of a soundwave, it will have no effect on the process of double sheet detection. You can come across a number of sensors available for different detection distances. When the presence of sheet or paper is detected, it is possible to adjust other processes according to the supply of sheets being led through some machine. This process helps in improving the overall efficiency of the detection mechanism while resolving errors quickly.

Our short video shows the Double Sheet Detector for offset printing machine and the printing process in action. Watch this video to get a complete look of the printing machine.

Once you have seen the video you can continue reading about how you can set up the DBK+ Sensors.

C] Setting Up DBK+ Sensors

For a typical DBK+ sensor for double sheet detection, the recommended mounting distance is 40mm, right from the transmitter to the receiver. In some cases, the distance can be altered between the range of 20 and 60mm. With the help of a reliable software solution, it is possible to configure the right mounting distance, especially while using the double sheet detection sensor for the first time.

It is also recommended that the double sheet detection sensor should be mounted with a proper inclined angle towards the particular material. It is true when you are working with thicker plates made out of materials like plastic, foil, cardboard, or metal. The suggested mounting angle for materials like cardboard sheets is greater than or equal to 35 Degrees. For plastic foils, the angle is 27 Degrees and for wafer, it is 11 Degrees.

D] Default Options or Customized Adjustments

The sensors are typically equipped with three inputs. These inputs help in configuring different settings for different materials and thicknesses. The configurations for different materials depend on the grammage of the plates or sheets that are expected to be detected.

The standard configuration is used on materials having a grammage of around 20-1200 g/m2. During the production process, it is possible to switch between different configurations.

Conclusion

Double sheet detection through a reliable system can enable a highly reliable solution. The sensors deliver added value through secondary diagnostics and data processing. Due to this, the overall system effectiveness can be improved effectively.

If you have any questions about identifying double layers or material sheets using our methods, don’t hesitate to reach out to us. We’re always here to help.