Improvements in Machines for Grinding Milling Cutters and the like."
Year: 1898

page_text: Date of Application, 6th Apr., 1898-Accepted, 30th July, 1898
COMPLETE SPECIFICATION.
Improvements in Machines for Grinding Milling Cutters and the like."
I, FREIDRICH SCHMALTZ, of Offenbach on the Main, in the Empire of Germany,
Manufacturer, 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:-
In the grinding machines hitherto known on which milling cutters and the like
could be ground, the arrangement has always been adopted of passing the cutter
to be sharpened by hand over a stationary grinding disc.
This invention has for its object to provide a perfectly automatically working
grinding machine wherein, in contrast to those previously employed, the cutters
to be sharpened or ground are stationary whilst the grinding disc itself is moved
over them. This arrangement has a number of important advantages. In the
first place, it allows of the parts (fingers, grippers or the like) which hold the
cutters during their treatment by the grinding disc, being also made to travel
with the disc. Moreover these parts no longer need as previously be specially
adjusted for each cutter but need only be adjusted to correspond to the wearing
away of the disc. Finally, the improved machine may be employed without further
trouble for any suitable form of milling cutter or the like
A form of construction of this machine is shown in the accompanying drawings,
in which
Figure 1 is a side elevation; Figure 2 a rear elevation; Figure 3 a front view
of the upper part of the machine; Figure 4 illustrates the grinding of spiral
milling cutters; Figure 5 the grinding of shaped milling cutters.
In this improved automatic grinding machine the grinding disc a is mounted
in the grinding disc head bin such a way that it may be adjusted in all directions
and may execute an up and down movement. The grinding disc head b is mounted
on a slide c which is horizontally movable in the upper part of a frame d.
This slide c is connected by a link w to a lever adapted to be oscillated by
any suitable mechanism, preferably by an adjustable crank pin c on a crank disc
mounted on the shaft of a worm wheel u driven by a worm f in order to impart
to said slide and thereby to the head b, a reciprocating movement. The milling
cutters g to be sharpened are fixed between pointed pins or centres h on a support i
and only require to be fixed at such a height that the grinding disc can engage
therewith in order that the grinding may commence at once.
This is rendered possible by the fingers k, which hold the cutters during the
grinding, being mounted in front of and behind the disc and fixed in such a way
on the grinding disc head 6 that they describe a reciprocating movement along
with the disc. They thus require only to be adjusted when the grinding disc is
considerably worn or when the position of the grinding diso is altered, otherwise
they are always ready for a correct engagement in the teeth of the cutter. The
movement or turning of the cutter is effected by means of a pawl 7 which is operated
by means of levers mn and à cam disc o when the grinding disc and the fingers
leave the cutter.
In order to always correctly press the cutter against the fingers ka cord q

page_text: weighted by means of a weight p is provided and adapted on the movement of the
cutter to slightly wind up on the latter. In order that by means of this cord
the cutters shall not turn back again when the grinding disc leaves their teeth,
a spring or spring pawl t is provided which engages in a tooth, of the cutter and
holds it until the fingers are re-engaged. In place of this spring the foremost
of the fingers may also be made to have a spring action. In this case on the
return of the dise the said finger must no longer leave the cutter.
Instead of the spring the turning mechanism may also be so operated that the
pawl 7 only returns when the fingers have again engaged.
The rotation of the cutter takes place intermittently and always at the moment
when the grinding disc a and the fingers, & are 'disengaged from the cutter. During
this period the cutter is only held by the spring t. The movement forward to the
extent of one tooth is effected by the pawl which is adjustably mounted on the
two armed lever m n operated by the cam disc o. When the cutter has been
pushed one tooth forward it is again fixed by the spring so that it cannot slip
back. The pushing forward mechanism l m n then returns and the fingers kand
grinding disc a again engage the cutter.
i
This intermittent movement of the cutter which is to be sharpened may take
place by means of any, suitable pawl mechanism, such as is well known already
in similar machines. In the present case the pawl is arranged on a bar, so
that it may be adjusted or moved to and fro according to the kind of cutter to
be sharpened. The bar is mounted on an arm m. This arm m. is capable of
being rotated or turned by means of a set screw m¹ in such a way that the position
of the pawl 7 may be adjusted somewhat more forward or backward according
to requirements. The whole meelianism forms together the one arm of the
lever mn which is pivoted at and moved by the cam o. The set screw m¹ and
the arm m are adjustable, in a plane at right angles to the plane of the paper.
This movement however is effected by hand and only when cutters of different
thicknesses are to be ground. In working, the parts n m m may be regarded
as a rigid whole pivoting on the point in the plate of the paper.
...
ידי
11
The grinding of shaped milling cutters takes place by the insertion of a tem-
plate whereby the vertically movable head 6 carrying the grinding disc may
be suitably raised and lowered in consequence of its reciprocating movement by
means of a guide roller z, a weighted levers being preferably arranged to cause it
to bear firmly against the template.
The grinding of spiral cutters takes place in the same way as before described
for the straight cutters and with the same mechanism except that the grinding, lisc
is placed obliquely as shown in Figure 4.
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 machine for automatically grinding milling cutters and the like, character-
ized by the grinding disc (a) and the parts (k) which hold the cutters (9) whilst
being ground, being arranged on a head (b) movable in all directions and adapted
to be moved together with said head automatically to and fro over the cutter (y)
to be ground, substantially as herein before described.
1.
2. In a machine for automatically grinding milling cutters and the like,, such
as described, the arrangement of a turning mechanism adapted to turn the cutters
at the moment when the fingers (k) or parts holding them are disengaged there,
from, a spring or spring pawl (1) being provided to retain them until the fingers (k)
have again engaged, substantially as described.
3. A modification of the machine hereinbefore described for automatically grind-
ing milling cutters and the like, which consists in omitting the spring pawlt and
adapting the front finger k to take it 'splace by providing said finger with a spring
action and arranging it to no longer leave the cutter when pushed forward, substan-
tially as described.

page_text: 4. In a machine for automatically grinding milling cutters and the like, such
as described, the arrangement on the same shaft of mechanism for reciprocating
the grinding disc and mechanism for effecting the turning of the cutter, substan-
tially as hereinbefore described.
TY
1 1
EAL
A 1000
WM. P. THOMPSON & Co.,
Of. 6, Lord Street, Liverpool, Agents for the Applicant.