Carpet pile lean angle monitor
This concept design is for an ‘on line’ carpet pile lean angle monitor.
Jamtech first produced a proof of concept design and then schemed a mechanism for automatic scanning of the carpet fibres.
In the production of fibre carpets there is a need for monitoring the lean angle of the fibres. The carpet fibres must lean at a specific angle and direction in order to maintain an invisible edge when one batch of carpet is laid adjacent to the next. If the lean angle and/or direction differ, then a visible line is perceived thus spoiling the overall appearance of the laid carpets.
Measuring lean angle is done using an optical technique and is normally carried out with a static off-line instrument requiring a sample piece of carpet to be cut from a recently manufactured 500 metre roll. Should the measured lean angle be out of specification then the appropriate adjustments are made to the production machine. The downside is, testing can only be done every 500m which means while the production machine is happily churning out a roll of carpet it could end up being scrapped or demoted to low grade stock.
To solve this problem, Jamtech came up with a solution that allowed monitoring of the carpet fibre lean angle during production. The key to success was to develop a sensor head that was immune to background light levels. We successfully demonstrated this with a working prototype. Further development is to ensue.
How is lean angle measurement done?
Consider a single fibre fixed to the carpet base shown below.
The fibre reflects light in a similar way to a mirror. If light from an emitter is directed at the fibre, a detector can be used to measure the reflected light. This is shown below with the emitter and detector (sensor head) at a low angle. Not much light is collected by the sensor as most is reflected away.
Now let’s move the sensor head, arc wise, to an angle that is perpendicular to the fibre. As a result, the detector collects more light as shown below.
If a number of readings are taken for various sensor head angles, a graph similar to the one shown below can be used to determine the point of greatest reflection. The lean angle is therefore at the peak. In this hypothetical example the fibre is leaning 15o from the vertical.
Real carpet fibres
Of course, in the real world carpet fibres are not exactly like mirrors. They don’t all neatly align, are obscured by one another and vary in colour. The amount of light reflected from the fibres is thus a lot less and considerably spread over the measurement range.
Jamtech used their expertise to demonstrate to the client through a feasibility study how a solution can be realised. This allowed the customer to gain confidence before committing to further development.