I'm afraid the only people that can give you such information is the belting suppliers. The value varies horrendously between the suppliers and can be used as a basis of determining if they really do have a suitable product. Unfortunately getting this information from them is also very difficult for the same reasons. ■

N S Hua,

Mr. Morgan is correct, you will see great variations in the modulus between different belts manufacture red in the US. This is due to the safety factor game that is played with Allowable Working Tensions. (AWT). The AWT is the force exerted on the sample during the modulus testing. The difference in modulus between an 8:1 safety factor belt and a 12:1 safety factor belt, given that the two samples will be subjected to the same max force, will be considerable.

On the international front, given that the belt is rated/sold under an actual breaking tension, not an AWT based on a safety factor, the numbers will fall in a more predictable range, however; do not kid yourself into thinking there are not plenty of games still played with the international rating of Kg/M, so you will still see variation.

Now, through in the fact that there are 3 major players in the yarn market, and numerous smaller ones, all using different types of polyester and nylon. Add the different fabric weavers, all using different equipment to twist the yarn, different looms to weave the fabric, different treating methods and materials, and you have a formula for end user confusion.

And, every manufacturer has a different spec for the same end belt specifications. Different yarn sizes in conjunction with different yarn counts will effect the modulus of a belt. And, on the front end, you have the elongation given by the amount of crimp in the yarns of the fabric. More variables!

All that said, if you are in the early design phase there are some assumptions that can be built upon. In a typical Polyester Warp (length yarn), Nylon Fill (cross yarn) fabric reinforced belt, you will typically see a modulus of 18,000 to 20,000. The lower the rating/AWT/break tension, the lower the modulus. The higher end premium type belting, perhaps 1,000-2,000 higher. In a Poly Warp/Poly Fill fabric reinforced belt, you will see a 1,000 to 2,000 gain in modulus due to the decrease in flexibility of the Poly Fill yarns vs. the more flexible nylon Fill yarns. In a Nylon Warp/Nylon Fill fabric reinforced belt, you will typically see a modulus of 8,000 to 10,000.

Those assumptions will allow you to get a general idea of what your transitions, etc. will need to be for your conveyor. But I stress, as Mr. Morgan said, that you decide on a belt supplier and get the exact modulus for the exact belt that you intend to put on the system. Otherwise you’ll be like so many that I’ve seen, a system designed and built with out a belt that will run on it because the belt was the last thing they purchased.

Ron Marler

Legg Co. Inc

www.leggbelting.com ■

I assume that you want to know the Modulus of Elasticity, also known as Belt Modulus -Bm, in the longitudinal direction. I assume that you want to use the Bm value in the radius of curvature constraint equations. Therefore you need to know the highest value (not to exceed value of Bm) for the possible variations in different types of carcass construction. The lower values of the range will result in more conservative design of your curves though at the expense of longitudinal stretch. the latter is handled by a take-up system that recognizes the possible low end of the Bm range.

Mr. Marler is right about the ambiguity in working (rated tension) strength Tr. The Bm is a characteristic of a given belt carcass construction but the Tr value varies for the same carcass according to the safety factor assigned by various manufacturers and various codes. For this reason it is better and less ambiguous to deal with the ultimate (breaking) tension Tu and to assign your own consistant safey factor according your evaluation of the governing standards (CEMA, ISO, DIN, etc). Thus the ratio Bm/Tu is the best unambiguous measusre of the belt's (sppecific) elasticity.

It is important to note that the same safety factor is not appropriate for the different carcass matreials. For stability of elongation reasons (the belt must ultimate stop stretching) a minimum SF=12 is required for nylon warp belting wheras SF=10 is adequate for polyester warp belt carcass.

Once you are able to frame your requirements in a technical spec you will be able to obtain the desired values or range of values from the belt manufacturers. ■

Dear Mr. Hua

The elestic module is also a function of geometric dimesions of pipe conveyor..You have to consider the geometric parameters, raw material properties and the kinematic parameters together..

Best regards ■

Dr.Ergun,

By definition the elastic modulus is the ratio of the static axial stress over axial strain. Geometry does not effect the modulus of elasticity. It effects the section moment of inertia which indeed effects the curature, but not the elastic modulus. Kinematics also does not affect this issue. Generally kinematics and hysterisis affect power consumption.

Joseph A. Dos Santos ■

Dear Mr Dos Santos,

A few years ago, I read a paper in the BSH on a "Square" shape conveyor belt. (Similar to Pipe but framed by four rollers).

I would be interested to find the manufacturer and know if you have developped some equipments based on it.

Thank you. ■

Mr. Känel,

The Square Belt, Square Conveyor System was (and I believe still is) a patented concept of SFBT, France. We were proposing to develop the system for licensing in a partnership of SFBT, DSI (Dos Santos International), another USA manufacturing company, AFM, the Canadian, North American partner of SFBT, and another Canadian manufacturing Company. DSI was to be the engineer and expert of this partnership.

After our much involvement and expense, at a meeting to launch a prototype plan, Dos Santos International was dropped from the partnership. To my knowledge the prototype was never built and I believe that the effort was eventually abandoned.

Joe Dos Santos ■

I believe the 'square' form configuration was termed U-CON?

Graham Spriggs may have some information on this configuration.

Regards,

Adi ■

Adi,

The Square Belt / Square Conveyor that we are discussing is not related to the UCON. It is/was an extension of a SFBT self-aligning belt that uses a rigid (planking) center panel over the center roll of a the troughing idler. This was in fact extended to created a triangular enclosed belt, a very modest application.

The Square belt was to utlise three such rigid panels to create three sides of the square and the limp ends to flap over and enclose the square.

Joe Dos Santos ■