An Improvement in Mills for Cutting Tea.
Year: 1893

page_text: Date of Application, 4th Nov., 1893
Complete Specification Left, 4th Aug., 1894-Accepted, 8th Sept., 1894
PROVISIONAL SPECIFICATION.
An Improvement in Mills for Cutting Tea.
I, CHARLES HENRY BARTLETT of 2, and 3, Welsh Back, Bristol, in the County
of Gloucester, Scale Maker and Manufacturer of Tea Mixing and Cutting
Machines do hereby declare the nature of this invention to be as follows :—
This invention relates to mills for cutting tea and has for its object to avoid the
injury to the cutting edges of the rollers and knives, frequently caused by nails
and other hard substances accidentally mixed with the tea.
The invention consists essentially in the combination, with a knife mounted to
revolve, of a spring detent by which the knife is normally retained in operative
position but which is free to yield should any obstruction get between the cutters,
and of friction gear adapted to come into operation as the detent yields to an
obstruction, the effect of the friction gear being to revolve the knife in such direction
that it recedes from the obstruction which is thus released and falls out without
causing injury to the cutters, the friction gear by its continued motion then
returning the same or another blade to operative position with regard to the
roller.
In order that the amount of tea which may pass through uncut, whilst the knife
after yielding is being moved round to operative position, may be reduced to a
minimum a number of such knives may be mounted around a common axis and
come into operative position successively, the peripheral face of the friction gear
being interrupted at points corresponding to the respective blades so as to move
the knife round only the distance from one blade to the next.
In order to make the arrangement as sensitive as possible and reduce to a
minimum the risk of injury to the cutting edges, especially when the cutting roller
is of such length that considerable pressure is necessary to hold the knife normally
up to its work, the knife may be divided at a point in its length, the spindles of
the two portions being independent and each acted on by detent and friction gear,
as described.
Dated this 4th day of November 1893.
C. H. BARTLETT,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.
COMPLETE
SPECIFICATION.
An Improvement in Mills for Cutting Tea.
I, CHARLES HENRY BARTLETT of 2 and 3 Welsh Back, Bristol, in the County
of Gloucester, Scale Maker and Manufacturer of Tea Mixing and Cutting
Machines, 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 :-
This invention relates to mills for cutting tea, which consist essentially of a
revolving cylinder presenting cutting edges acting in conjunction with a stationary
knife, and the invention has for its object to avoid the injury to the cutting edges
of the cylinder and the knife which is frequently caused by nails and other hard
substances accidentally mixed, with the tea.

page_text: The invention consists essentially in the combination, with a knife mounted to
revolve upon journals, of a spring actuated detent by which the knife is normally
retained in operative position but which is free to yield to excess of pressure, and
of friction gear adapted to come into operation after the detent has so yielded, the
yielding of the detent allowing the knife to recede from the obstruction to which
the excessive pressure is due and the friction gear continuing the motion until the
knife blade is returned to operative position with regard to the cylinder.
During this receding motion of the knife, the nail or other obstruction is carried
round by the cylinder until it falls out of the machine so that no injury is done by
it either to the revolving or stationary cutting edges.
In order, however, to reduce to a minimum the amount of tea which may pass
through uncut, whilst the cylinder is revolving inoperatively during the yielding
motion of the knife and its return to operative position it is preferred to mount a
number of such knives around a common axis so that they shall come into operative
position successively, the peripheral face of the friction gear being interrupted at
points corresponding to the respective blades so as to move the knife round only
the distance from one blade to the next.
Reference is to be had to the accompanying drawings forming a part of this
Specification, wherein,
Figure 1 represents a part sectional plan and Figure 2 a part sectional end
elevation of a tea cutting mill provided with two cutting cylinders and two sets of
yielding stationary knives.
Figure 3 is a cross section of the same on line 3-3 Figure 1.
Figure 4 is a sectional elevation of the friction gear and knife holding detent
mechanism taken on line 4-4 Figure 2.
Figures 5 and 6 show details of an intermediate bearing for the stationary knives
when the latter are divided into independent lengths separately controlled and
operated by detent and friction gear from both ends of the machine.
The same letters of reference indicate the same parts in all the figures.
A is the box or chamber of the mill in which the cutters are mounted. B, B, are
two cutting cylinders journalled in the ends of box A geared together
so as to be
rotated in opposite directions by the revolution of a single winch handle bor
equivalent mechanism, and each constructed in the usual way of a number of cast
iron discs juxtaposed upon a shaft, each disc presenting a number of peripheral
cutting edges with intermediate cells whose size and depth regulate the length to
which the tea is cut, by the said cutting edges acting in conjunction with the two
sets of stationary but yielding knives C, C. As the detent and friction gear is
alike for both sets of knives it will be sufficient to describe one set.
Each set of stationary knives is composed of preferably, three cutting blades c
attached by bolts or screws to wings cast on a common boss or shaft but there may
be a greater or a lesser number of cutting blades, the detent and friction gear being
modified accordingly.
The detent mechanism by which any one of the knives is held in operative
position for the cylinder to act against consists of a lever D having a notch d in
which engages any one of a series of lugs e fixed to disc E fast on the knife shaft,
the portions of the lugs around the edge of the disc E being of course in proper
relation to the respective knives and to the detent D so that when a lug is engaged
in the notch d the corresponding knife will be presented in operative position to
the cylinder B. The detent lever D is pressed upon by a strong spring Facting
through a plunger G sliding in the spring box and the face of the notch d against
which the lug e abuts is not radial to the knife axis but inclined at such an angle
that although it will resist the tendency of the knife axis to revolve under the
normal pressure of cutting tea, an excess of pressure due to a nail or other
obstruction caught in the cells of the cylinder being brought against the stationary
knife, as shown at the right hand side of Figures 2 and 3, will cause the lug
acting against the inclined face of the notch d to raise the detent lever D against
pressure of the spring and so allow the lug to escape. When the lug is thus
e

page_text: disengaged from the detent the latter offers no further obstruction to the rotation
of the knife shaft, the detent resting clear of the disc E on a stationary ear d² fixed
to the frame until the next lug comes round into position of engagement with
the notch d.
I is a "mutilated" friction wheel fast on the knife shaft, having as many
peripheral notches as there are knives on the shaft located in such relation to the
knives and to a friction pinion K on the cylinder shaft that when a knife is in
operative position a depression of the friction wheel I will be opposite to the
friction pinion K as shown at the left hand side of Figure 2 so that the latter will
then be out of frictional contact with the wheel I. The frictional surface of the
wheel I is formed by an encircling band of india-rubber which is depressed into
each of the peripheral notches of the wheel by a metal strap screwed to the
wheel, the part of the strap which lies in the depression being of the form indicated
by the dotted section lines its outer surface being within the circle of the outer face
of the friction band i. The partial revolution of the knife axis consequent on the
yielding of a knife to an obstruction as above described, brings the rubber faced
eriphery of the friction wheel I into operative contact with friction pinion Kas
shown at the right hand side of Figure 2 so that the receding motion of the knife
in the direction of the arrow (Figures 2 and 3) is continued by the action of the
friction gear until another knife has come into operative position whereupon the
knife axis will be re-engaged with the detent and the friction wheel will be out of
contact with the pinion by which it was rotated.
When the cutting roller is of such length that the resistance of the detent
necessary to hold the stationary knife normally up to its work is considerable it is
preferred to make the knives and their shafts in two independent sections of equal
length the inner ends of the shafts being journalled in an intermediate lug L, fixed
to the casing, as shown in plan in Figure 5 and in transverse sectional elevation
in Figure 6.
Each section of the knife shafts is provided at its outer end with detent and
friction gear, as above described, so that either section may turn independently of
the others. In this way the mill is rendered as sensitive as possible to obstruction,
and risk of injury to the cutting edges, as well as loss of efficiency in the mill (on
account of tea passing through uncut) is reduced to a minimum.
It.will be understood that wherever a knife shaft is furnished with a flange c² for
the support of the wings carrying the knife blades, the cylinder should be furnished
with a plain or non-cellular disc 61 of a breadth corresponding to that of such
flange, so as to prevent any tea passing through the mill uncut; whilst in order to
prevent tea or other substances becoming wedged between the said flange and disc
and thus stopping the mill, a fence or packing block M should be applied as shown,
a somewhat similar fence, consisting of a rectangular bar, being applied as at N for
the purpose of preventing uncut tea dropping between the cylinders at any point
in their length.
I am aware that it has heretofore been proposed to mount the stationary knife so
that it might be made to recede from the cutting cylinder by partial rotation about
its own axis in order to give passage to an obstruction. But only a single knife
blade has been so employed, such blade being returned backwards to operative
position by a spring or weighted lever, there being no continuous rotary movement
away from the obstruction nor any provision by the use of two or more knives
mounted upon the same shaft, for reducing the amount of tea passed through
uncut. Moreover, hitherto it has not been found possible in practice to effectually
preclude the possibility of the blade returning to its operative position before the
obstruction has been entirely ejected, so that the risk of damage to the machine by.
the obstruction being retained between the cutting edges of the knife and cylinder
has not been obviated.
In my machine as above described, the obstruction must necessarily press first
more or less against the face of the knife and so cause the knife to recede before
the obstruction can get between the cutting edges and since, when the knife shaft

page_text: has once been released from the detent, no further obstruction is offered to its
continued receding motion, but it is in fact caused to recede still further by the
friction gear, the obstruction is liberated without ever actually coming between
the cutting edges at all.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. In a tea mill, the combination, with the revolving cutting cylinder and with a
stationary knife or set of knives journalled upon an axis parallel to the cylinder
and with detent mechanism for retaining the same yieldingly in operative position,
of friction gear adapted to come into operation after the knife has been moved out
of engagement with the detent mechanism and to impart a continued motion to the
knife in the same direction so as to move it farther from the cylinder and return it
or bring another knife into operative position by such continued rotation,
substantially as and for the purpose specified.
2. In a tea mill, the combination, with the stationary knife or set of knives
journalled upon an axis parallel to the cylinder, of the particular construction of
.spring detent mechanism herein described for retaining the knife yieldingly in
operative position substantially as and for the purpose described.
3. In a tea mill, the combination, with the cutting cylinder, of a set of two or
more knives on the same shaft journalled so as to rotate under the control of
suitable mechanism so that when the shaft is partially rotated to move one knife
out of operative position another will be simultaneously brought into operative
position by the same motion of the shaft, substantially as and for the purpose
specified.
4. A tea mill having in combination with the revolving cylinder a set of knives
divided into independent lengths or sections each journalled upon an axis and
combined with detent mechanism and friction gear adapted to act as specified and
claimed, the adjacent ends of the two sections being journalled in an intermediate
bearing substantially as and for the purpose specified.
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.