Improvements in Rotary Cutters.
Year: 1892

page_text: COMPLETE SPECIFICATION.
Improvements in Rotary Cutters.
I, WILHELM LORENZ, of Karlsruhe, Baden, Germany, 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:
My invention relates to an improved construction of rotary cutters wherein the
cutting edges are formed on separate steel cutter bars which are provided on their
inner sides with teeth that gear with corresponding teeth carried by the cutter
head, which run parallel with the axis thereof, or, at a slight angle thereto, and
which for example may be formed as a screw thread or worm rotatable on an axis
parallel with the axis of the cutter head. The said teeth of the cutter bar having
been brought into the required position in gear with the said teeth or screw thread
or worm, they are locked in that position, by means of wedges or other suitable
means. The longitudinal pressure to which the cutter bar is subjected in cutting
is thus transferred to the teeth or screw thread of the cutter head, any giving way
being prevented by the wedge or other locking device, so that the cutter bar is
virtually as of one piece with the cutter head.
If the teeth of the cutter head are formed as a screw thread or worm as described,
the rotation hereof can be made to adjust the cutter bars to the exact position
required, and such screw thread may either be made to act upon a single cutter bar or
simultaneously upon all the cutter bars, moving them all forward or backward, to
the same extent.
The cutter bars are made of a tapering cross section, fitting into correspondingly
tapered grooves of the cutter head. By this means any looseness and consequent
lateral yielding of the cutter bars is prevented.
If the above mentioned wedge lock is formed as a pressing ring surrounding all
the cutter bars, as will be presently described, it will at the same time serve to
press the cutter bars into the tapering grooves.
The cutter bars are, as a rule, placed at an angle to the cutter axis; the
inclination being either inwards or outwards.
On the accompanying drawings are shewn by way of example various rotary
cutters constructed according to my invention.
Figure 1 shews a part longitudinal section and a part end view of a construction
in which the cutter head a is formed with teeth placed at a slight angle to its axis,
and with eight grooves c for the cutter bars, the grooves being made to taper
towards the cutter axis. The teeth b, extending in annular form all round the
cutter head, are made to project at about the middle of the said grooves which are
made with an interruption for this purpose.
Into the latter are fitted the corre-
spondingly tapered cutter bars d, so as to fit with their sides against the sides of
the grooves, while their toothed inner face takes into the teeth 6 of the cutter head.
Upon the latter is screwed a pressing ring e which is made to bear with its inner
face formed to correspond with the inclination of the cutter bars, upon the outer
surfaces hereof, so that on rotating such ring and thus screwing the ring towards
the left hand on the cutter head, the inclined surface of the ring will be made to
press the cutter bars firmly into their grooves c and into the teeth b.
Figure 2 shews a side view partly in section and a front view of a similar cutter
head with eight cutter bars having teeth on their inner sides, which gear with
eight wheels or discs f carried by the cutter head and having a screw thread or
worm formed on their periphery, which wheels may be considered as sections of a
tapering screw bolt, so that by the rotation of each wheel, the position of the
corresponding cutter bar can be accurately adjusted. The cutter bars, are, as

page_text: previously described, pressed into their grooves and in gear with the wheels f by
means of a conical pressing ring e screwed upon the cutter head.
If one or more of the cutter bars require to be adjusted, the pressing ring is
slackened back so as to allow of the bars being moved forward or backward by
rotating their wheels f. After the adjustment the pressing ring is tightened up
again so as to secure the cutter bars in their adjusted positions.
Figure 3 shews a longitudinal section and part transverse section of a modification
in which, in place of the wheels f with screw threads, there are provided threaded
bolts 9, the threads of which gear with the teeth of the cutter bars. For this
purpose corresponding borings are formed through the cutter head, in which the
screw bolts can turn freely and which have a longitudinal slot extending along
their entire length so as to expose a portion of the screw thread, with which the
teeth of the cutter bar can consequently engage.
Figure 4 shews a cutter head with an appliance for simultaneously adjusting all
the cutter bars.
It consists of a disc i arranged rotatably on the cutter head and having at its
periphery a screw thread which gears with the teeth of all the cutter bars d. The
inclined position of the cutter bars, and the action of the pressing ring e thereon is
the same as before described.
Figure 5 shews an arrangement similar to the foregoing one, with the sole
difference that in this case the cutter bars d are arranged with an outward slope
instead of an inward one, for the purpose of under-cutting the work &c. The
pressing ring is consequently formed with an outward sloped pressing surface.
Figure 6 shews a modified arrangement of the pressing ring. This is, in this
case, not screwed with a thread upon the cutter head, but is connected thereto by
screws k by which it can be screwed forward or backward, so as to securely hold or
set free the cutter bars.
Figure 7 shews a further modification, shewing an arrangement for turning the
pressing ring upon the cutter head. The ring is for this purpose provided with
teeth on its periphery with which gears a worm m, carried by the cutter-head, and
by the rotation of which the pressure ring is turned so as either to press upon the
cutter bars or to release them.
Figure 8 shews a construction in which the pressing ring is replaced by a number
of pressing bars n corresponding to the number of the cutter bars. The cutter
head is in this case formed with openings of a tapering section, in which the
prismatic cutter bars k, as also the tapering pressing bars n, are situated.
The latter are moved inwards or outwards for tightening or loosening the cutter
bars by means of screws p screwing into the cutter head.
The above described construction may be otherwise modified in various ways
without departing from the nature of the invention; thus for example in Figures 1
to 4 and 6 to 8 the cutter bars might be sloped outward as at Figure 5 instead of
inward. Or the manner of gearing the parts together and of actuating the same
can be varied; thus the cutter bars might be arranged with their teeth on the outer
instead of on the inner side; also, in some cases the cutter bars may be arranged
parallel to the axis of the cutter head.
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 :-
1. A. rotary cutter whose cutting edges are formed upon adjustable bars having
teeth along one side thereof, with which are made to gear corresponding teeth or
screw threads upon or carried by the cutter head, for the purpose of adjusting the
cutter bars substantially as described.
2. In a rotary cutter such as is referred to in the first claim, arranging the teeth
or threads that gear with those of the cutter bar upon wheels or discs for upon
bolts g, substantially as described.
3. In a rotary cutter such as is referred to in the first claim, arranging, the teeth

page_text: or threads that gear with those of the cutter bar upon a disc i that is made to
actuate all the cutter bars simultaneously, substantially as described.
4. In a rotary cutter, such as is referred to in the first claim, effecting the locking
of the cutter bars with the teeth of the cutter head, or of a part carried thereby,
either by a conical pressing ring e, which is made to act simultaneously upon all
the cutter bars, or by means of pressing bars n acting separately upon each cutter
bar, substantially as described.
Dated this 5th day of December 1899
ABEL & IMRAY,
Agents for the Applicant.