IMPROVEMENTS IN APPARATUS FOR FORMING ROTARY CUTTING AND SHAPING TOOLS
Year: 1878

page_text: LETTERS PATENT to Henry Simon, of No. 7, St. Peter's Square, Manchester,
A
in the County of Lancaster, for the Invention of "IMPROVEMENTS IN
APPARATUS FOR FORMING ROTARY CUTTING AND SHAPING TOOLS."
communication from abroad by Ernst Schiess, of Düsseldorf, Oberbilk, in the
German Empire.
Sealed the 11th October 1878, and dated the 30th April 1878.
PROVISIONAL SPECIFICATION left by the said Henry Simon at the Office of
the Commissioners of Patents on the 30th April 1878.
HENRY SIMON, of No. 7, St. Peter's Square, Manchester, in the County of
Lancaster. "IMPROVEMENTS IN APPARATUS FOR FORMING ROTARY CUTTING AND
SHAPING TOOLS." (A communication from abroad by Ernst Schiess, of Düsseldorf,
Oberbilk, in the German Empire.)
In rotary cutting and shaping tools, such as rose cutters, screw taps, and the like,
it is necessary for their proper action that the periphery of the tool should be sloped
off or made to recede in rear of the cutting edges. This is at present effected by
filing or cutting off by hand such rear portion of the periphery to the required extent
after the teeth have been formed, whereby it will be seen that if the width of the
tooth tapers in thickness, as is usually the case, the radial profile thereof will alter
in configuration on grinding it up after it has become blunt.
The present Invention has for its object :-
Firstly. To produce such receding form of the tooth by means of the slide rest in
a lathe.
-
And, Secondly. To make the tooth so formed of such a configuration that the
cutting face will always present a radial profile of the same configuration when
ground up after having become blunt.
This latter result is only obtainable by forming the tooth according to the archi-
median spiral, which is produced by causing a point to travel with uniform velocity
along a straight line, which at the same time revolves with uniform velocity round
a fixed centre.

page_text: For so forming the tooth according to the present Invention the apparatus is
arranged as follows:-The blank for the cutting tool being made to revolve at a
uniform speed in the lathe, the part of the slide rest carrying the cutter has at the same
time a uniform transverse motion imparted to it, whereby it is caused to cut the sur-
face of the tool in rear of the cutting face of each tooth in the form of the archimedian
spiral. For imparting this motion to the cutter on the slide rest it is mounted on
a slide which can move transversely on the bed of the slide rest, and which
carries on its under side a small roller or stud fitting in a revolving cam groove
mounted on a spindle carried by the bed of the slide rest. This cam groove is
of a helical form, returning by a sudden bend into itself, so that during the greater
part of its revolution it causes the slide with its cutter to advance with uniform
speed towards the axis of the tool blank, while this is at the same time revolving
with uniform speed, and at the end of such forward motion it is moved rapidly back
to its original position.
The cam is mounted on a spindle, the outer end of which has a bevil pinion in
gear with another pinion capable of sliding along, but caused to revolve with a shaft
carried at the side of the lathe bed and driven by the lathe gearing, the boss of the
said pinion on the shaft being embraced by a fork or collar on the bed of the slide
rest, so as to keep it always in gear with the first-named pinion when the slide rest
travels along the lathe.
The speed of the cam spindle is so proportioned relatively to that of the tool
blank as to cause the cutter to make one, two, three, or more transverse to-and-fro
motions while the blank is making one revolution, according as one, two, three, or
more teeth require to be formed on the circumference of the blank.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Henry Simon in the Great Seal Patent Office on the 14th
October 1878.
HENRY SIMON, of No. 7, St. Peter's Square, Manchester, in the County of
Lancaster. "IMPROVEMENTS IN APPARATUS FOR FORMING ROTARY CUTTING AND
SHAPING TOOLS." A communication from abroad by Ernst Schiess, of Düsseldorf,
Oberbilk, in the German Empire.
In rotary cutting and shaping tools, such as rose cutters, screw taps, and the like,
it is necessary for their proper action that the periphery of the tool should be sloped
off or made to recede in rear of the cutting edges. This is at present effected by
filing or cutting off by band such rear portion of the periphery to the required
extent after the teeth have been formed, whereby it will be seen that if the width of
the tooth tapers in thickness, as is usually the case, the radial profile thereof will
alter in configuration on grinding it up after it has become blunt.
The present Invention has for its object :-
-
Firstly. To produce such receding form of the tooth by means of the slide rest in
a lathe.
And, Secondly. To make the tooth so formed of such a configuration that the
cutting face will always present a radial profile of the same configuration when
ground up after having become blunt.
This latter result is only obtainable by forming the tooth according to the archi-
median spiral, which is produced by causing a point to travel with uniform velocity
along a straight line, which at the same time revolves with uniform velocity round
a fixed centre.
For so forming the tooth according to the present Invention the apparatus is
arranged as follows:-The blank for the cutting tool being made to revolve at a
uniform speed in the lathe, the part of the slide rest carrying the cutter has at the
same time a uniform transverse motion imparted to it, whereby it is caused to cut
the surface of the tool in rear of the cutting face of each tooth in the form of the
archimedian spiral. For imparting this motion to the cutter on the slide rest it is
mounted on a slide which can move transversely on the bed of the slide rest, and
which carries on its under side a small roller or stud fitting in a revolving cam groove
mounted on a spindle carried by the bed of the slide rest. This cam groove is of
helical form, returning by a sudden bend into itself, so that during the greater
part of its revolution it causes the slide with its cutter to advance with uniform
speed towards the axis of the tool blank, while this is at the same time revolving with
uniform speed, and at the end of such forward motion it is moved rapidly back to
its original position.
The cam is mounted on a spindle, the outer end of which has a bevil pinion in
gear with another pinion capable of sliding along, but caused to revolve with a
shaft carried at the side of the lathe bed and driven by the lathe gearing, the
boss of the said pinion on the shaft being embraced by a fork or collar on the
bed of the slide rest so as to keep it always in gear with the first-named pinion
when the slide rest travels along the lathe.
The speed of the cam spindle is so proportioned relatively to that of the tool
blank as to cause the cutter to make one, two, three, or more transverse to-and-fro
motions while the blank is making one revolution, according as one, two, three, or
more teeth require to be formed on the circumference of the blank.
DESCRIPTION OF THE DRAWINGS.
Fig. 1 shews the cross section of a lathe bed with slide rest, constructed and
onerating according to the before-described Invention.

page_text: The slide rest A, carried by the lathe bed B, has a spindle C with pinion C
which is rotated by means of a sliding bevil pinion D on the shaft E, the
rotation of this shaft being so timed with the rotation of the lathe centres that
the spindle C is caused to make as many revolutions during one revolution of the
lathe centres, and consequently of the cutter blank at X, as there requires teeth
or cutting faces to be formed on the latter.
On the spindle C is fixed or formed a cam groove C of helical shape, returning
into itself, into which takes the small steel roller F on a pin F" fixed to the under
side of the slide G carrying the cutting tool H, so that at every revolution of the
spindle C the slide and tool are first made to advance with a slow uniform motion
towards the centre of the lathe, and are then caused to recede rapidly again, this
operation being repeated as many times during one revolution of the cutter blank X
as teeth have to be formed on the latter. The cutting tool H can be advanced on
the slide G by the screw G¹ in a well-known manner.
Any looseness in the motion of the spindle C with its cam groove is prevented by
causing the one face of the cam groove boss to bear against a hard steel face I fixed
on the slide rest, and by making the end of the spindle C abutt against a hard steel
pin J beld by an adjustable screw J'. The slide rest can be moved along the lathe
by the screw spindle K in the ordinary manner, and by throwing the pinion D out
of gear with C and fixing the slide G on A, the lathe may be made to act as an
ordinary lathe with self-acting screw spindle.
For operating on conical or tapering blanks for screw taps the slide rest is.
adjusted in a corresponding oblique position. By the above means it will be seen
that each tooth of the cutter will be made to recede in a radial direction from its
cutting face in such manner that every point of the toothe will be clear of the groove
cut by such face, and that such cutting face when ground up will always present the
same radial profile, so as to be capable of being used after repeated grindings.
Fig. 4 shows a side view, and Fig. 5 a cross section of a rose cutter; and Fig. 6,
a cross section of a screw tap, with teeth formed as above described.
Having thus described the nature of this Invention, and in what manner the:
same is to be performed, as communicated to me by my foreign correspondent, I
claim,―
First. The use, for forming the teeth of rotary cutting and shaping tools of a cutter
made to advance with uniform speed towards the axis of the tool blank while the
blank is revolving at uniform speed, whereby the teeth are formed so as to recede
in a radial direction behind the cutting face, according to the archimedian spiral,
substantially as herein described.
Second. The use, for forming the teeth of rotary cutting and shaping tools, of a
slide rest, the cutter of which is made to advance at a uniform speed towards the
axis of the blank by means of a revolving helical cam groove carried by the slide
rest and acting on the cutter slide, substantially as herein described with reference to
the accompanying Drawings.
In witness. whereof, I, the said Henry Simon, have hereunto set my hand
and seal, this Twelfth day of October, in the year of our Lord One thousand
eight hundred and seventy-eight.