Year: 1886

page_text: I, CHARLES JAMES DOBBS, of Middlesborough, in the County of York, do hereby
.declare the nature of this invention to be as follows:-
Paving blocks made of blast-furnace scoria or slag have the disadvantage that by
the chilling action of the moulds in which they are cast, the outer skin assumes a
very hard smooth texture that tends to slipperiness.
According to my present invention I so manufacture such blocks that instead of
presenting the bard skin of the block as the wearing surface, I present a fractured
surface of the block which does not possess the glassy texture of the skin. For
this purpose I form the moulds for the blocks of sufficient size to make two or
more blocks and at the part of the mould corresponding to the division of the
blocks into separate lengths, I form projecting ribs or fillets on the bottom and
sides of the mould having a V shape and I also place across the top of the mould
a V shaped bar, so that on running in the liquid slag, a V shaped groove is formed
all round the block.
4
i
After this has solidified and has been annealed in the usual manner, I subject
the block to a blow whereby it will be fractured at the point where the groove
has been formed, and this more or less rough fractured surface I then use as the
wearing surface of the block.
.

page_text: I, CHARLES JAMES DOBBS of Middlesborough in the County of York do
hereby declare the nature of this invention and in what manner the same is to
be performed to be particularly described and ascertained in and by the following
statement:
Paving blocks made of blast furnace scoria or slag have the disadvantage that by
the chilling action of the mould in which they are cast, the outer skin assumes a
very hard smooth texture that tends to slipperiness.
According to my present invention I so manufacture such blocks that instead of
presenting the hard skin of the block as the wearing surface, I present a fractured
surface of the block which does not possess the glassy texture of the skio. For
this purpose I form the moulds for the blocks of sufficient size to make two or
more blocks and at the part of the mould corresponding to the division of the
blocks into separate lengths, I form projecting ribs or fillets on the bottom and
sides of the mould having a V shape and I also place across the top of the mould
a V shaped bar, so that on running in the liquid slag, a V shape groove is formed
all round the block.
After this has solidified and has been annealed in the usual manner, I subject the
block to a blow whereby it will be fractured at the point where the groove has
been formed, and this more or less rough fractured surface I then use as the
wearing surface of the block.
Fig. 1 of the accompanying drawings shews a perspective view of a double slag
block cast with V shaped grooves a a as above described and Fig. 2 shews one half
of the block after being fractured across the grooved part, so as to produce a rough
fractured surface b for the wearing surface. Fig. 3 shews a transverse section of the
form of mould which I employ by preference for forming the grooved double block.
Fig. 4 shews the same view with the mould opened, Fig. 5 shews a sectional front
view of the mould.
The mould is formed of two separate parts c, d hinged together at e, the part c
being fixed to a turntable on the periphery of which a number of such moulds are
fixed. The two parts are held together in the closed position shewn by the catch ƒ,
thus forming a rectangular box in which are projecting V shaped fillets
9 g, and
also a V shaped bar gi fixed to the part c and projecting across the open top of the
mould. The one side h of the mould (shewn in dotted lines in Figs. 3 and 4) is
also formed on the part c and serves as the attachment to the turntable, while the
other side h¹ and the bottom h³ are formed on the part d.
The liquid slag being run into the mould and having solidified, the catch fis
released, whereupon the part d of the mould with the block in it will drop into
the position shewn at Fig. 4, when the block will fall out, having the configuration
shewn in Fig. 1.
Although I prefer to cast the blocks with a V groove on all four sides, yet, a
single groove, or two grooves on opposite sides may be sufficient.

page_text: Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is:
The manufacture of slag blocks having a fractured surface for their wearing
surface, by casting a block of slag with a groove or grooves at one or more points
of its length and then fracturing the block at such groove or grooves, substantially
as herein described.