Acoustic roofing tile inspection system
With the use of the acoustic roofing tile inspection system each tile is tapped by a special hammer system. The hammer system consists essentially of a ball-bearing, which is set so that the hammer touches each tile passing by at precisely the same spot each time. Both the duration and position of the stroke can be programmed. The reproducibility is of great importance for the precision of the acoustic inspection.
The acoustic tone of each struck tile is recorded by a directional microphone. The quality is then determined by a frequency performance analysis. The configuration of the acoustic inspection is done by storing the values of good tiles during the production process. It is of vital importance that the system takes into account the typical acoustic tone deviations caused by differences in the material or temperature fluctuations in the kiln, so that these do not lead to identification of scrap in large quantities later on.
The spectral analysis is done in special high-frequency conditions. Up to three different frequency ranges are used, which are then decisive for predefinition of the “tone” of a roofing tile. With the help of these three frequency ranges, a performance profile is defined by measuring the spectral performance density of the released sound. On the basis of the majority of the profiles, the processor generates a so-called ensemble of all recorded roofing tiles.
The specific acoustic-samples recorded in this way can be stored within a “measuring job” and called up again at any time. The test accuracy can be secured with help of one single parameter. This is done by means of percentage designation 0% = very incorrect up to 100% = very correct. There is very little to be regulated, which was a major development target of ibea.
In combination with ibea’s digital image processing Odin III – as stand-alone version – acoustic defects can now be recognized, without risking higher rejections through fluctuations caused by production.
Acuspect is highly qualified for recognition of open cracks, structure abnormalities, edge fractures etc.
The system is built up on Windows and in a stand-alone operation has its own PLC for control of the hammer mechanism and rejection of damaged roofing tiles. The processor includes a special A/D converter to record the directional microphone signals. The processor and the switchboxes are integrated in the control desk.
Technical data
› Recording frequency: 50–18 000 Hz
› Cycle-rate: up to 120 roofing tiles/min
› Power: 230 V/16 A
› Casing: Rittel E-Rack 0.65 · 1.2 m
› Casing protection: IP 42
› Ejector: MAC valve with the corresponding cylinder
› Hammer system: double-bearing hammer arm with electronic valve
› PC: IPC Eltech Cybox with 250 GB exchangeable hard disk, USB Adapter,
Ethernet connection, ibea Acuspect RTS, Windows system software, ibea Acuspect Analysis
