Improvements in Sand Blast Machinery and Processes.
Year: 1891

page_text: Date of Application, 8th Aug., 1891
Complete Specification Left, 6th May, 1892-Accepted, 11th June, 1892
PROVISIONAL SPECIFICATION.
Improvements in Sand Blast Machinery and Processes.
1, JEREMIAH EUGENE MATHEWSON of Bellefield Works, Sheffield, Engineer,
do hereby declare the nature of this invention to be as follows
In the ordinary sand blast machine the velocity is given to the sand by a current
of air steam &c., in their passage through a blast pipe or gun which forms part of
the apparatus and is used only for the purpose of giving the velocity to the sand.
The energy stored up in the moving sand by this one single application of the
current of air steam &c., is the only force available for doing work, and as it acts
only in the straight line of its motion the sand gives but one single efficient impact
upon the object, and its force is thereby mostly spent, and the effect of its rebound
upon other parts is almost nil. In some cases, for instance the cleaning of the
inside surfaces of long or tortuous tubes or passages from sand scale or other
impurities it is difficult or impossible to direct the sand in a straight line upon the
desired spot.
My invention consists in giving and renewing the velocity to the sand in either
straight or oblique directions by successive and repeated impulses derived from a
current of air &c. which is kept up steadily and continuously throughout all the
length of the tube or passage treated, whether straight or crooked, and through
any side branches leading from it so that the grains of sand which have struck the
side of the tube and rebounded from it shall have a renewed velocity imparted to
them by the current of air and shall strike again with efficient velocity further on
in the tube and again rebound, and so on repeatedly through all the length of the
tube and its various outlets and angles. The impelling current of air &c. will flow
through such side outlets or passages with velocity but slightly diminished, and
the sand will follow the air and receive renewed velocity from it, though its
direction may be changed. The tube or passage treated and any outlets leading
from it thus become part of the sand blast apparatus, and the continuous current
of air sent through them is of sufficient pressure to give the requisite velocity to
the sand.
The volume of the impelling current of air &c. may be economized by placing
temporary cores in the centre of large tubes and by closing some of the outlets so
as to concentrate the current in the others. The impelling current of air may be
produced either by pressure or by partial vacuum and I prefer the latter. Baffle
plates of suitable curves or angles may be used to direct the current of air and
sand and may be moved about during the operation. In cleaning the inside of
cylindrical tubes I have found it useful to give, by baffle plates or otherwise, a
whirling or spiral motion to the currents of air and sand so that the centrifugal
force will cause the sand to rub upon and abrade the surface but I do not confine
myself thereto.
I sometimes reverse the direction of the currents of air and sand in the tube or
passage treated so as to act upon parts which have escaped the first application.
In this manner the most tortuous and intricate cored passages in castings may
be cleaned. By the term sand I mean grains of any hard and sharp mineral or
metal such as quartz, emery iron and steel.
Dated this 7th day of A woust 1891

page_text: COMPLETE SPECIFICATION.
Improvements in.Sand Blast Machinery and Processes.
I, JEREMIAH EUGENE MATHEWSON of Bellefield Works, Sheffield, 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 :-
In the ordinary sand blast machine the velocity is given to the sand by a current
of air, steam &c. in their passage through a blast pipe or gun which forms part of
the apparatus and is used only for the purpose of giving velocity to the sand. The
energy stored up in the moving sand by this one single application of the current
of air steam &c. is the only force available for doing work, and as it acts only in
the straight line of its motion the sand gives but one single efficient impact upon
the object, and its force is then mostly spent, and the effect of its rebound upon
other parts is almost nil, In some cases, for instance the cleaning of the inside
surfaces of long or tortuous tubes or passages from sand, scale or other impurities
it is difficult or impossible to direct the sand in a straight line upon the desired
spot.
My invention consists in giving and renewing the velocity to the sand in either
straight or oblique directions by successive and repeated impulses derived from a
current of air &c. which is kept up steadily and continuously throughout all the
length of the tube or passage treated, whether straight or crooked, and through
any side branches leading from it, so that the grains of sand which have struck the
side of the tube and rebounded from it shall have a renewed velocity imparted to
then by the current of air and shall strike again with efficient velocity further on
in the tube and again rebound, and so ou repeatedly through all the length of the
tube and its various curves outlets and angles.
The impelling current of air &c. will flow through such side outlets or passages
and round the corners with velocity but slightly diminished, and the sand will
follow the air and receive renewed velocity from it, though its direction may be
changed many times. The tube or passage treated or any outlets leading from it
thus become part of the sand blast apparatus, and the continuous current of air
sent through them is to be of sufficient pressure to give the requisite velocity to
the sand.
The volume of the impelling current of air &c. may be economized by placing
temporary cores in the centre of large tubes and by closing some of the outlets so
as to concentrate the current successively in the others. The impelling current
of air may be produced either by pressure or by partial vacuum and I prefer the
latter. Baffle plates of suitable curves or angles may be used to direct the current
of air and sand to particular spots, and may be moved about during the operation.
In cleaning the inside of cylindrical tubes I have found it useful to give, by baffle
plates or otherwise a whirling or spiral motion to the currents of air and sand so
that the centrifugal force will cause the sand to rub upon and abrade the surface
but I do not confine myself thereto.
I sometimes reverse the direction of the currents of air and sand in the tube or
passage treated so as to act upon parts which have escaped the first application.
In this manner the most tortuous and intricate cored passages in castings may
be cleaned. By the term sand I mean grains of any hard and sharp mineral or
metal such as quartz, emery, iron and steel.
The following is a method of carrying my invention into effect. Referring to
the annexed drawings
Fig. 1, is a vertical section of the apparatus, shown as operating on a steam
engine cylinder the internal passages of which are to be cleaned from sand
scale &c.
Fig. 2, is a section of a straight pipe similarly to be cleaned.
made in much fic

page_text: 1, is a settling chamber for spent sand made air tight and placed preferably in
the floor of the foundry. 2, is the casting of the cylinder of a steam engine, the
crooked passages of which are to be cleaned. It communicates with 1, by the
opening 3, and is closed air tight in other parts except 4, which is the crooked
passage intended to be cleaned from sand scale &c. 5, is the outer opening of 4,
through which the current of cleaning air and sand enter. 6, is the sand hopper
delivering a regulated supply of sand through the trough 7, into the opening 5.
8, is a steam jet exhausting apparatus making a partial vacuum, of say to two
pounds per square inch in the chamber 1, and causing a strong current of air to
enter at 5, and carry the sand with great velocity through the passage 4. 9 is the
manhole to remove the sand which settles in the chamber 1.
The operation is as follows. The inside of the cylinder 2, is made to com-
municate with the chamber 1, & all its openings except 5, are closed air tight.
The steam jet exhauster 8, is started and causes a strong current of air to pass
through 4. A regulated supply of sand is fed from the hopper 6, through the
trough 7, into the passage 4, where it impinges against the moulding sand scale &c.
to be removed and finally settles at 10, in chamber 1,
One
In Fig. 2, 11 is a long straight pipe the inside of which is to be cleaned.
end of it is connected air tight with the settling chamber 1, and the sand hopper 6,
and trough 7, are supported at its other end. On starting the steam jet exhauster,
the sand is carried in by the current of air thus created and on its passage through
the pipe impinges against the irregular or rough surfaces of moulding sand scale &c.,
and cuts them away and carries them into chamber 1.
In order to economize power in cleaning straight pipes and to concentrate the
blast near the surface to be cleaned, a core 12, may be inserted, either as a plain
cylindrical rod or tube or having a spiral thread so as to give the sand a whirling
or centrifugal motion. In cleaning tortuous passages baffle plates may be in some
cases advantageously used to throw the sand upon particular spots. They may be
protected by caoutchouc or other elastic material, and should be arranged to suit
the requirements of each case.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is;
In sand blast machinery and processes the following devices either separately
and individually or in combinations of any two or more of them-viz. :—
1. Giving to the sand a renewed velocity, after it has struck the object and
rebounded therefrom, by successive and repeated impulses from a continuous current
of air, steam &c., kept up in or over the article treated.
2. Baffle plates placed so as to deflect the currents of air and sand to particular
spots.
3. In pipes or passages, the interior surfaces of which are to be cleaned, the use
of temporary cores, so as to concentrate the currents of air and sand near the
surfaces intended to be cleaned.
4. Spiral fins or threads on the cores to give a whirling or centrifugal motion to
the sand.
5. Reversing the direction of the currents of air and sand in or over the article
treated.
All substantially as described.
J. E. MATHEWSON.