IMPROVEMENTS IN OR APPERTAINING TO ROLLER MILLS FOR GRINDING AND OTHER PURPOSES
Year: 1884

page_text: I PIETER VAN GELDER, of Sowerby Bridge, in the County of York, Milling
Engineer do hereby declare the nature of my said invention for "IMPROVEMENTS
IN OR APPERTAINING TO ROLLER MILLS FOR GRINDING AND OTHER PURPOSES "
be as follows:-
to
Roller mills driven at a differential speed for grinding farinaceous matters if
driven by ordinary gearing or even by diagonal toothed or V-toothed gearing, are
found to cause the surface of the rolls to assume the form of a polygon with a vast
number of sides-showing that there is a slight slip between each tooth. To avoid
this I have tried chain gearing, but this has not proved successful to fully obviate
this difficulty, and others have tried belt gearing with differential pulleys, but the
slip in this case is in my experience worse than when gearing is used. Again it is
almost impossible to effect absolutely even feeding, and if. from any cause the rolls
run dry-if allowed to touch each other they grind each other and ruin the
granulating surface. To prevent this distance pieces have been inserted between
the bearings to keep them from actually touching, but as the bearings and also the
journals in them wear, the distances between the centres alter and these distance
pieces become useless.
Now my invention is designed to avoid these evils, and it consists in running
the rolls with friction pulleys at each end-these friction pulleys being themselves
my distance pieces. The friction pulleys are practically spur gearing with an
infinite number of teeth at infinitely small distances apart, and the slip from the one
infinitely small tooth to the next is infinitesimal or nil-and even if not nil-is
evenly distributed over the entire circumference of the pulley so long as its surface
is truly cylindrical.
Now I form my pulleys one preferably of hard cast iron the other of leather on
edge, paper, homogeneous composition or vulcanite, or other suitable homogeneous
material, taking care to use precisely the same quality of material thoroughout, and
consequently-especially seeing I have differential speeds on the pulleys-the wear
is uniform and is very slight. By having a series of change wheels differing say a
sixty fourth of an inch in circumference and changing as required, the distance
apart of the rolls is exactly regulated and the slight wear that in time takes place
can be made good by change of wheels.

page_text: The power of the friction rollers to resist slipping must be at least 25 per cent
more than the power expended in grinding or crushing. For heavy grinding the
rollers must therefore be broad.
In order to estimate the amount of differential speed-or of the slip or of both―
I put a small pulley on each roller shaft and two large equal pulleys on independent
shafts on the same axis and place a pointer on each working over a dial. These
pointers going much slower than the rollers but in equal ratio to their respective
rollers will show their respective speeds-and the ratio between those speeds.
Doted this 20th day of January 1884.

page_text: "
1 PIETER VAN GELDER of Sowerby Bridge in the county of York, Milling
Engineer do hereby declare the nature of my said invention for "IMPROVEMENTS
IN OR APPERTAINING TO ROLLER MILLS FOR GRINDING AND OTHER PURPOSES
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement :-
Roller mills driven at a differential speed for grinding farinaceous matters if
driven by ordinary gearing or even by diagonal toothed or V toothed gearing, are
found to cause the surface of the rolls to assume the form of a polygon with a vast
number of sides showing that there is a slight slip between each tooth. To avoid
this I have tried chain gearing but this has not proved successful to fully obviate
this difficulty and others have tried belt gearing with differential pulleys, but the
slip in this case is in my experience worse than when gearing is used Again it is
almost impossible to effect absolutely even feeding, and if from any cause the roll
run dry, if allowed to touch each other they grind each other and ruin the
granulating surface. To prevent this, distance pieces have been inserted between
the bearings to keep them from actually touching, but as the bearings and also the
journals in time wear, the distances between the centres alter and these distance
pieces become useless.
Now my invention is designed to avoid these evils and it consists in running the
rolls with friction pulleys at each end, these friction pulleys being themselves
my distance pieces. The friction pulleys are practically spur gearing with an
infinite number of teeth at infinitely small distances apart, and the slip from the
one infinitely small tooth to the next is infinitesimal or nil, and even if not nil is
evenly distributed over the entire circumference of the pulley so long as its surface
is truly cylindrical.
The invention is best described by aid of the accompanying drawings of a mill
as actually constructed by me. For simplicity and ease in understanding the
drawings, I have omitted those parts of the machinery which form no part of the
invention, such as the base, the feed, and delivery mechanism.
Figure 1 is a side elevation of a machine with feed hopper removed.
Figure 2 plan of same.
Figure 3 side elevation of the rollers on a larger scale.
In these A is the framework of the machine B B₁ Bu Bill four rollers made
preferably of the very hardest chilled cast iron of these B and B are in sliding
bearings d. ds and B¹ and B in stationary ones dd, but free to adjust themselves
to the shaft. These four rollers are not turned truly cylindrical but with a slightly
larger diameter toward the centre than at the sides, the amount of difference being
a few thousandths of an inch at most. This is to allow for a very slight amount
of elasticity which I have found to exist in the rollers and shaft. C C¹¹¹
C111 shafts of rollers. D D' D¹¹ D¹¹¹ bearings of same. The bearings or brasses
D D D D are fitted into the blocks d d', d, d³, these blocks are fitted between
the slides A¹ A' carried by the framing and those carrying the outer rollers slide
freely to and fro controlled by the springs. K are oil tubes through which oil is
supplied to the bearings (of the rollers. coiling rollers working in a well in the
hearings. k oil tubes fitted with caps k through which the spent oil may be
drawn off from the bearings of the shafts. E E E E volute springs bearing
against the bearings on one side and the nuts I on spindles e e' e²e on the other.
Spindles e and e² and their springs E¹ E' are not absolutely required, while the
apparatus is at work, but are very useful when a stoppage occurs to automatically
draw the rolls of each pair respectively apart the moment the pressure of the lovers,
hereafter described is taken off. Levers fƒ³ oscillating on pins f f bear against
the ends of spindles e and es respectively, and are themselves actuated by links f
and f' and handle levers F F¹.

page_text: In the drawing, F is shown in the position taken, when the pressure on the roll
bearings is released F¹ in the position where it is full on. GG GG are the
friction pulleys. In the case of rolls B and B¹ for coarser stuff, their pulleys G G¹
are made with a larger difference in diameter than in the case of the other pair for
finer stuff. These pulleys must be made of hard and perfectly homogenous
material. After numerous experiments I have found pulleys of the hardest chilled
cast iron to be the best. These are set in their shafts by conical keys g g¹ g² g³ as
I find that ordinary keys cause a slight wobbling or eccentricity fatal to good work.
HH driving pulleys.
The mode of action is as follows
The levers being set in the position shewn at F¹ the mill is worked with an even
continuous feed. Should at any time the feed go wrong or the rollers have to be
stopped while the feed is going on or other action occur by which an increase of
feed occur too great for the rollers to grind, the levers are put in the position shown
at the F end in the drawing, the springs E¹ then pressing between their bearings
and nuts push the bearings of roll B outward. The two friction rollers no longer
touch each other, roll B stops but roll B¹ runs on and works off the superfluous
feed. By simply turning handle F back into a similar position to that shown at F¹,
the rolls are again placed in gear, the pulleys acting as distance pieces, thus while
in an ordinary mill it might take an hour or two after the rolls have been thrown
out of gear to get them set exactly right; by my frictional arrangement, they can
be instantly readjusted to their exact right position.
Seeing I have differential speeds on the pulleys the wear is uniform and is very
slight. By having a series of change wheels differing say a hundreth of an inch
in circumference, and changing as required, the distance apart of the rolls is
exactly regulated and the slight wear that in time takes place can be made good by
change of wheels.
The power of the friction rollers to resist slipping must be at least 25 per cent
more than the power expended in grinding or crushing. For heavy grinding the
rollers must therefore be broad, and as shown in the drawing Figure 2, I use
broader pulleys for the fine grinding rolls than for the coarser.
In order to estimate the amount of differential speed or of the slip or of both,
I put a small pulley on each roller shaft, and two large equal pulleys on independent
shafts on the same axis and place a pointer on each working over a dial. These
pointers going much slower than the rollers, but in equal, ratio to their respective
rollers will show their respective speeds, and the ratio between those speeds.
I have not thought it worth while to cumber the drawing with this apparatus,
as any millwright could manufacture it from the above description.
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.
1st. The roller mills for grinding and other like purposes, geared with friction
pulleys acting as distance pieces substantially as and for the purposes described.
2nd. In combination with roller mills geared by friction pulleys the apparatus
for indicating the differential speed substantially as described.
Dated this 98th dow of notahan 1001