Improvements in Machine Tools.
Year: 1889

page_text: Date of Application, 18th Jan., 1889
Complete Specification Left, 18th Oct., 1889-Accepted, 23rd Nov., 1889
PROVISIONAL SPECIFICATION.
Improvements in Machine Tools.
I, WILLIAM THOMAS ROWDEN, of Lenzie, in the County of Dumbarton, North
Britain, Professor of Applied Mechanics, in the Glasgow and West of Scotland
Technical College do hereby declare the nature of this invention to be as follows:-
My invention has for its object to obtain an improved motion in machine tools for
surfacing, slotting, or otherwise cutting metals or other materials, wherein the cutting
is effected by a reciprocating motion derived from a motion of rotation by means of a
crank or disc with an excentric pin and connecting rod jointed at one end to the
revolving crank pin and at the other either directly, or indirectly by the aid of a lever
or levers, to the reciprocating part whether tool holder or bed.
My invention consists of an arrangement whereby a more uniform motion is given
to the reciprocating part of the machine during its cutting stroke and a quick return
or non cutting stroke is secured.
In carrying out my invention I take a single check or overhanging crank, or a disc
with an excentric pin, and which I shall hereafter call the first crank, and I connect
its pin with a connecting rod the other end of which is jointed, either directly or
indirectly to the reciprocating part, but instead of giving this first crank a uniform
motion of rotation as in ordinary machines I give it a motion which changes
continuously during a revolution so that it rotates with greater average velocity
during the return stroke than during the cutting stroke and thus secures a quick
return motion.
It also has greater velocities at and near the beginning and end of the cutting
stroke than it has at the middle parts thereof and thus the well known irregularity of
the motion of a reciprocating part which exists when the crank revolves uniformly is
considerably modified.
This variable motion of rotation I obtain by a modification of the mechanism
described in my provisional specification relating to improvements in motors worked
by gas or other combustible bodies No. 5774, 1888, and which I apply as follows :—
In front of and at a short distance from the first crank or disc I put a second
similar crank or disc face to face with the first and mounted on a separate axle which
is parallel to the line of the axle carrying the first crank but not in the same straight
line. The two crank pins are connected by a link of suitable length, the piu of the
first crank being extended for that purpose.
The second axle is driven uniformly by any suitable means and thus a variable
motion is imparted to the first crank and by selecting suitable relative dimensions for
the various parts and proper relative positions for the two axles the desired motion of
rotation is obtained.
For example, if in a shaping machine where the tool is carried by a horizontal
sliding part and the above named axles are horizontal I make the two crank lengths,
or radii of the crank pins, and the connecting link of equal lengths and place the
second axle vertically over the line of the first and at a distance equal to one half of
a crank length then a cutting stroke is obtained of improved uniformity of motion
and the return stroke is effected in about one half the time taken for the cutting
stroke.
To vary the length of the cut the dimensions referred to must be made adjustable,
but this may also be accomplished by a modification which consists in driving the
reciprocating part by a separate crank or disc at the other extremity of the axle
carrying the first crank. An adjustable crank pin in this supplementary crank or disc
enables cuts of different lengths to be made without altering the nature of the motion

page_text: of the reciprocating part provided that the radius of this supplementary crank be
parallel to the radius of the first crank and on the same side of their axis of
rotation.
Dated this 17th do. of Tamu 1000
WILLIAM T. ROWDEN.
COMPLETE SPECIFICATION.
Improvements in Machine Tools.
I, WILLIAM THOMAS ROWDEN of Lenzie, in the County of Dumbartonshire North
Britain, Professor of Applied Mechanics in the Glasgow and West of Scotland
Technical Collego 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 has for its object to obtain an improved motion in machine tools for
surfacing, slotting, or otherwise cutting metal or other substances wherein the cutting
is effected by a reciprocating motion derived from a motion of rotation by means of a
revolving crank or dise with an excentric pin and a connecting rod jointed at one end
to the pin of the revolving crank or disc and at the other either directly or indirectly
to the reciprocating part.
My invention consists of an improved combination of mechanisms whereby a fairly
uniform velocity is obtained for the reciprocating part of the machine during the
cutting stroke, as well as a quick return stroke.
In carrying out my invention I take a single cheek or overhanging crank or a disc
with an excentric pin and connect the revolving pin by a rod to the reciprocating part,
but instead of giving this crank or disc a uniform motion of rotation I give it a motion
which changes continuously during a revolution so that it rotates with greater average
velocity during the return stroke than during the cutting stroke and thus secures
a quick return motion. It also rotates with greater velocities at the beginning and
end of the cutting stroke and thus very considerably modifies that well known
irregularity of the motion of a reciprocating part which is driven by a crank and
connecting rod.
This variable motion of rotation I obtain by modifications of the combination of
mechanisms described in my specifications No. 5774, 18th April 1888 and which
consists essentially of two cranks or discs with their pins mounted face to face on
axles which are in parallel lines but not in the same straight line, the two pins being
connected by a link.
As showing one of the arrangements for applying my invention I show outline
drawings of the combination applied to an ordinary shaping machine with a horizontal
cut.
The slide S carrying the cutter is reciprocated by the revolution of disc A with its
pin B made adjustable to give different lengths of cut.
A is attached to an axle C which is supported by a bracket K¹ which is part of the
saddle carrying the slide S.
To axle a second disc or cank D is attached, which carries the pin E. G is
another disc having pin F and supported by the axle H which is carried by another
bracket Kas before.
Axles H and C are not in the same line, as shown in the elevation.
G is here made into a toothed wheel and is driven with uniform rotation by the
pinion K which slides along the shaft L which is driven by suitable means. By this
combination A will receive a variable motion of rotation and by suitably adjusting the
relative dimensions of crank lengths, length of connecting link E. F. and distance
between lines of centres of axles, and the relative positions of these two lines of
centres, the desired motion of the reciprocating part is obtained.
Thus if radii C E & H F and length of link E F be made equal, and the distance

page_text: between centre lines of axles C & H about one half these lengths, the axle of driving
wheel G being nearly vertically over the line of axle C and the rotation as shown by
arrow, the cutting stroke will be done with fairly uniform velocity of the cutter
and the return stroke will be done in about one half the time taken by the cutting
stroke.
A. modification of the same combination may be made as shown in the freehand
sketch.
1 is the toothed wheel connected by a small axle to disc 2. This axle passes
excentrically through a fixed axle 8, which carries the disc 6, to one side of which is
attached the arm 5 for carrying pin 4. Pins 4 and 3 are connected by a link, and the
connecting rod to the slide is attached to the adjustable pin 7.
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 :-
The combination of two cranks or discs with excentric pins carried by axles whose
centre lines are not in the same straight line the pins being connected by a link for the
purposes set forth and in a manner substantially as described.
Dated this 17th day of October 1889.
WILLIAM T. ROWDEN.