Year: 1885

page_text: I, BENJAMIN CHEW TILGHMAN, of 42 Sandiway Road, Altrincham, Cheshire,
Engineer, do hereby declare the nature of this invention to be as follows:-
The sand blast has heretofore been used for frosting metal surfaces and it is
known that the fineness of the grain of the frosting can be varied to some extent
according to the size of the grains of sand used and the velocity with which they
are driven.
Now I have found that in metals which have a crystalline structure the erosive
action of the sand is more rapid upon those sides of the crystals which lie nearly
perpendicular to its path, than upon the points and edges which lie at a sharp
angle thereto, and that the relief or projection of the crystalline points can be
increased by continuing the action of the sand blast for a considerable time,
and in this way a grain or roughness of variable degrees of coarseness can be
produced,
My invention consists in the application of this differential or selective action of
the sand blast upon crystalline metals so as to grain or roughen them to any
desired degree.
One particular purpose to which this process is suitable is the preparation of the
surfaces of chilled iron rolls to be used for grinding grain. The roll previously
turned or ground to the proper shape is mounted on centres and rotated and moved
end wise under the sand blast so that all parts are equally subjected to the action.
At first a very fine frosting is produced, but as the action is prolonged the points
and edges of the crystals, which resist better than the flat sides, will gradually
become more and more prominent, and the operation is to be continued until the
proper degree of relief has been obtained.

page_text: Roughening of Metal Surfaces.
I, BENJAMIN CHEW TILGHMAN, of 42 Sandiway Road, Altrincham, Cheshire,
Engineer, 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 :—
The sand blast has heretofore been used for frosting metal surfaces and it has t
been known that the size of the grain of the frosting can be varied to some extent
according to the size of the particles of the sand used and the velocity with which
they are driven. Now I have found that in metals which have a crystalline
structure the erosive action of the sand blast is more rapid upon those sides of the
crystals which lie noarly perpendicular to its path than upon the points and edges 1
which lie at a sharp angle thereto, and that the relief or projection of the crystalline
points can be increased by continuing the action for a considerable time, and in
this way a granulation or roughness of variable degrees of coarseness can be
obtained.
My invention consists in the application of this differential or selective action of 1
the sand blast upon crystalline metals so as to granulate or roughen them to a
desired degree. One particular application of the invention is in the preparation
of the surfaces of chilled iron or steel rollers or disks to be used in grinding
semolina or other grain products.
Hitherto these rollers have generally been used smooth or nearly so, but their
grinding quality can be greatly improved by giving to their surface a gramulation
of the proper degree of coarseness.
The simple application of the sand blast will produce on the smooth surface of a
chilled iron roller only a very fine frosting, too delicate and minute in its degree of
projection or relief to be useful in the grinding process. But by continuing the
action of the sand blast for a considerable time the flat sides of the crystals are cut
away and the points and edges are developed and become more prominent, and the
frosting will grow gradually coarser, and finally a granulation can be obtained
equal or superior for grinding purposes to the surface of porcelain rollers.
By regulating the time of exposure to the sand blast, various and regulated sizes:
of granulation can be produced which are more suitable for certain stages of the
gradual reduction process of grinding than the surface of porcelain rollers, which is
generally of a uniform character.
The
This peculiar action of a long continued sand blast upon crystalline metals has
not heretofore been used or described, and its application to the production of
graduated degrees of granulation on such metals, and particularly to rollers and
disks used for grinding grain products, is the basis of my invention.
following is a method of carrying my invention into effect, taking for example a
chilled iron roller which is to be roughened for the purpose of grinding semolina.
Referring to the drawing the roller a is supported opposite the sand blast
apparatus b, so that only a small part of its surface c is exposed to the action of

page_text: the sand which is driven on it horizontally. The axle of the roller rests in
hooks d d which are fastened to bars e e¹ and hang on the frame ƒ ƒ, Fig. 2, which
runs on the upper rail R by the wheels w w, and on the lower rail R¹ by the
slides h h
One end of the axle has a crank g, Fig. 2, fastened to it by which it can be
rotated by hand. The other end of the axle is fastened to a long screw, s, so that
when the roller is rotated it is also moved end ways.
In this way every part of the surface is brought in succession opposite the
aperture o which admits the sand, and the operation of rotating the roller and
moving it end ways is continued forward and backward until the exposure to the
sand blast has been prolonged sufficiently to produce the desired degree of coarseness
in the granulation.
I find that about ninety minutes exposure to a sand blast driven by steam of
70 lbs pressure will give a useful degree of granulation to a roller 9 inches in
diameter and 18 inches long. About ten minutes exposure to the same sand blast
would give the same roller the fine frosting such as has hitherto been obtained by
the sand blast operated in the usual way.
One of the bars e¹ Fig. 2, is made moveable on the frame f so as to take in rollers
of various lengths.
The form of apparatus for producing the sand blast which I prefer to use, is that
patented to J. E. Mathewson, December 5th, 1884, No 15980, and I refer thereto
for the detailed description. Other forms of apparatus for producing the sand
blast are now well known and used in the arts.
Any of them capable of producing a sand blast of sufficient force and regularity
could be used, but I prefer the apparatus of Mathewson.
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
1. The process of roughening crystalline metal surfaces so as to produce
graduated degrees of granulation, by submitting such surfaces to the action of the
sand blast for lengths of time proportionate to the degree of coarseness desired,
whereby the points and edges of the crystals are developed, substantially as
described.
2. In the manufacture of rollers or disks made of crystalline iron or steel for
grinding grain products, the process of producing surface granulation of granduated
coarseness or relief, by the application of the sand blast for lengths of time pro-
portionate to the degree of coarseness desired, so as to develope the points and
edges of the crystals, substantially as described.
3. As a new article of manufacture rollers and disks for grinding grain products
made of crystalline iron or steel, having a graduated roughness produced on their
surface by the action of a sand blast operated so as to develope the points and
edges of the crystals to the desired degree of relief by a proportionate length of
exposure, substantially as described.
ALLISON BROS,
Agents for the Applicant.