IMPROVEMENTS IN MACHINERY FOR MAKING CAMS, AND FOR CUTTING AND SHAPING METALS AND OTHER MATERIALS
Year: 1858

page_text: PROVISIONAL SPECIFICATION left by Pearson Hill at the Office of the
Commissioners of Patents, with his Petition, on the 26th January
1858.
I, PEARSON HILL, of Hampstead, in the County of Middlesex, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN MACHINERY FOR
MAKING CAMS, AND FOR CUTTING AND SHAPING METALS AND OTHER MATERIALS," to
be as follows:-
In constructing cams for various descriptions of machinery it is desirable to
give them such shapes that the motions communicated to them may vary in
velocity or in amount according to certain determinate ratios. Thus in many
cases the cam may be constructed on the basis of a double parabola, so that
the acceleration of the velocity may be similar to that of a falling body, while
the retardation of the velocity is the converse of the same. In other cases the
crank motion or line of sines may be used, and the arithmetical spiral may be
employed when a uniform motion is required. Cams are generally made to
act upon a roller at the end of a lever, and the curves require to be modified
according to the diameter of the roller and the length of the lever. Concentric
parts of different diameters and extending over different ares of the circle are
also often required. . I construct a machine in which the cam to be cut is
mounted on a mandril or shaft, which is caused to revolve slowly by means of
an endless screw or worm wheel, or otherwise. In front of or over the cam is
a lever, whose effective or virtual length is variable, and is adjusted so as to
be equal to that of the lever which is to carry the roller which is to work on

page_text: or in the cam. The fulcrum of the lever is also adjusted so as to correspond
(with that of the roller lever. This may be effected by moving the fulcrum of
the lever, or the support of the mandril, or both. The lever carries a circular
cutter, whose position can be varied, and which may consist of one or more
cutters fixed in a chuck or plate, and adjusted at a distance from the centre
equal to the radius of the roller which is to work on or in the cam. If the
cutter be now made to revolve rapidly while the cam revolves slowly, and if at
the same time the cutter lever be caused to move at the rates and at the times
and to the extent that the roller lever is required to move, the effect will be
that the cutter will cut the cam to the required shape. I communicate the
required relative motions to the cutter lever and to the mandril by means of
original cams of any desired form, or by a crank motion, or other means in
connection with the geering of the machine. The extent and the times of the
motions are adjusted by means of inclined planes, or a bar or bars whose
inclination can be varied in connection with change wheels, variable levers,
pulleys with steel bands, or other similar means, so as to cause the cutter
lever and the cam to move at the proper rates, and through the required arcs
for producing the particular form of cam required. The cam which is to be
cut may be of metal, or of wood, or other suitable material, and if it be a
grooved cam both sides of the groove may be cut at the same time. If the
cam is to be made of cast metal the pattern may be cut in the machine, and
after the cam is cast it may be finished by cutting it in the machine, if
necessary. The details of the machine admit of variation. Thus, if the cam
be required to act upon a roller or stud moving in a rectilinear direction, in
lieu of a circular direction, a similar rectilinear motion is to be communicated
to the cutter, or in some cases the cutter may be mounted upon a lever of so
great length in proportion to its motion, that the slight deviation of the
motion from a straight line may be disregarded. It will be obvious that a
great variety of shapes for ornamental or other purposes, as well as for cams,
may be cut by the machine by varying the adjustments and the original
cams.