Describing the Kingston Hot Press in the making at the site powered by the WordPress… The last in many coincidences that led to this involvement. Before going on with the story about the press itself, let me step back a bit and paint the background. This journal entry, as the previous one, reads “Published by Darko Matovic at July 18, 2007 in lesotho”. The reader may well picture me contributing this from Lesotho, while in reality I have yet to get there, and will, later in the year. For now, this subtitle designates the category. And categories, as much as being vital and unavoidable, can be misleading, limiting. My current posts come from Kingston, Canada, where I teach at Queen’s University. This is where the idea of designing and building the hot press came, after hearing about the efforts to startup composites production in Lesotho, using local fiber and recycled plastic. Too many names to include all here, and many more to come, but I’ll mention Caroline Baillie, Ignazio Crivelli Visconti , Joseph Thaba, Bule Luru, Sebajoa Tau… Here at Queen’s, Timothy Thamae, Stanley Aghedo, Ryan Marien and myself are busy and excited putting the prototype together. With this background in mind, let me get to the press in more detail.
The hot press is essentially made of three functional units: (1) the lids, (2) the lifting mechanism and (3) the stand. The “core press”, consisting of the first two units is shown below in the triaxial view:
The top and the bottom lid are similar. Both are welded frames, each made of four “C” channels and two “I” (or rather “H”) beams. Each frame supports a square plate, two plates pressing against each other, squeezing the tile in between. Inside the frame, there are three “U” shaped electric heaters in each lid, attached to the back of the plate, in between the frame “ribs”, i.e. the steel profiles. The steel profiles are BIG, 200 mm high (8 in). This is what you need when trying to press a 0.6×0.6 m area with 200 tons, and not allow for more than 0.5 mm buldging in the middle. At least this is what the finite element simulation says. We’ll soon discover if this is right, not enough, or an overkill. This is what prototypes are for.
The top and bottom lid are similar but not identical. The top one has two C channels on the opposite side oriented otward, while the bottom has all four C channels pointing inward, mitred and welded as a picture frame. Here’s the top frame in the making, photo taken today:
