Page 45 - Апрель

FOUNDRY PRODUCTION

To obtain tubular and curvilinear models, we used the feature of many foams sintered
(glued) from granules, in particular expanded polystyrene, that products from them in thin
sections with a thickness of 0.1 - 4 mm can not break when bending, but at the same time
have a limited ability to deformation without destruction. In thicker sections, when bending, a
crack occurs along the junction of the granules. The specified maximum thickness depends on
the size of the sintered granules, the quality of the sintering and the material of the granules.
If a flat element is obtained in a mold with wedge-shaped samples, then a thickness of 0.1
mm is filled with small granules of expanded polystyrene, and a thickness of up to 4 mm is
quickly baked and firmly glued, allowing the element to be bent, shifting from the plane by a
small acute angle. Exceeding this size leads to the appearance of cracks, which can appear
during storage, transportation or mounting of a rolled element with other parts of the model.
The flexural strength of the element increases 2.5 - 3 times when glued with mesh or film. For
example, using PVA glue, from the side that becomes convex when the element is folded, which
allows you to increase the specified thickness to 5 - 6 mm.

Figure 6 shows, in side view, an example of
the bending of a flat member on the right side.
This element in the form of a plate with segments
1 and notches 2 when folding is secured with a lock
3. For example, according to the "thorn-groove"
system. If the sum of the angles of the wedge-
shaped samples is 360 °C, then when folding into
a closed system, the sides of all wedge-shaped
selections are closed so that in the assembly they
form a solid body by the thickness of segment 1,
and reducing the thickness of a flat element due
to selections does not reduce the thickness of the
element's wall in collapsed form.
The flat element of the gasified model can be
produced continuously. For example, for the method
[6] (rather seemingly fantastic) by composing it
from parts and building it up in the process of molding into a facing layer of a moving mold
in the form of a sandy evacuated form, it should only be rolled up into a continuous tubular
structure before molding, which can also be fastened with the above lock along the axis around
which the folding is performed.
Copying the structure of carbon nanotubes, Fig. 7 shows a structural element of the model,
made by analogy with them (the near curved wall of the mesh tube is shown by double lines,
and the far one - by one line). When magnified, a nanotube looks like a flat layer of graphite
atoms coiled up into a tube called graphene, which is a layer of carbon atoms connected by sp-2
bonds into a hexagonal two-dimensional crystal lattice. The mesh foam tube model consists of
repeating partitions 1 (instead of straight line segments representing bonds between atoms)

Stanochniy park 45