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Патент USA US3086420

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' April 23, 1963
L. ZIMMERMANN
3,086,410
TREPANNING TOOL
Filed Jan. 23, 1961
2 Sheets-Sheet 1
.4
INVEN TOR.
gyms ZA'IMEPMA/V/V
April 23, 1963
L. ZIMMERMANN
3,086,410
TREPANNING TOOL
Filed Jan. 23, 1961
2 Sheets-Sheet 2
INVENTOR.
[0/045 Z/mmMMA/v/v
\
30/
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ATTO/P/Vfy
United States
atent O ”
2
1
3,086,410
>
TREPANNING TOOL
Lukas Zimmermann, 5755 Bloom?eld Glens Road,
Birmingham, Mich.
Filed Jan. 23, 1961, Ser. No. 84,245
3,086,410
Patented Apr. 23, 1963
in a cylindrical bore 24 and the wall of said cylindrical
bore 24.
_
To accomplish the trepanned cut, the work piece 21
may be rotatably held while the trepanning tool 20 is
?xedly mounted in axial aligned or axial o?set relation
ship with respect to the center of the trepanned cut,
' 2 Claims. (Cl. 77-69)
according to whether or not the trepanning tool 20 has
been sharpened. Of course, the trepanning tool 20 may
This invention relates to cutting tools and in particular
be rotated while the work piece 21 is ?xed. In either
to trepanning tools.
For the purpose of this application, trepanning is best 10 instance, a proper axial vfeed of the trepanning tool into
the work is required. The trepanning operation may be
de?ned as a cutting operation which produces in a ?n
accomplished on a lathe or other machine tool incorpor
ished work piece an annular recess providing a cylin
ating means for holding the work, means for holding
drical boss located concentrically within a cylindrical
the trepanning tool, means for rotating the work with
bore.
The primary object of the invention is to provide an 15 respect to the trepanning tool, or vice versa, while ad
vancing the tool axially toward and into the work, and
improved trepanning tool which produces accurate ?n
means for offsetting the axial alignment of the center
ished work pieces with great economy.
line of the trepanning tool in respect to the center line
Another object of the invention is to provide an ex
of the trepanning cut.
tremely e?icient and economical tool for performing
trepanning operations that eliectively handles the chips 20 As shown throughout FIGS. 1-9 inclusive the cutting
end of the trepanning tool 20 is axially hollow at 25
from deep trepanning cuts and which is readily sharpened
by simple conventional tool sharpening procedures.
and is bifurcated forming two arcuate cutting arms or
elements 30 and 40 having cutting teeth 31 and 41 re
Other objects of the invention will become apparent
spectively located in a diametrical plane “A—A” through
by reference to the following detailed description taken
in connection with the accompanying drawings, in which: 25 the longitudinal axis of the said tool.
FIG. 1 is an exploded view showing a trepanned work
piece with a trepanning tool embodying the invention
removed therefrom.
FIG. 2 is an enlarged longitudinal sectional view of
a work piece with the trepanning tool embodying the 30
invention positioned in cutting relationship therewithin.
- It will be observed that the cutting tooth 31 is shaped
to perform as a boring tool, and, as the trepanning tool
20 is fed axially into the work, the cutting tooth 31 will
bore the diameter “a” of the cylindrical bore 24 form
ing the outer annular portion 220 of the annular recess
22 as indicated in FIG. 2. Simultaneously the cutting
tooth 41, which is shaped to per-form as a turning tool,
turns the diameter “11” of the cylindrical central boss 23
FIG. 3 is a cross sectional view taken on the line 3—-3
of FIG. 2.
forming the inner annular portion 221 of the annular
FIG. 4 is a longitudinal sectional view of a work piece
similar to FIG. 2 with the improved trepanning tool 35 recess 22 as indicated in FIG. 2. In other words, the
said cutting teeth 31 and 41 combine to cut the annular
positioned in cutting relationship therewithin but with
recess 22 and ?nish the annular bottom 222 thereof, each
the trepanning tool turned 90 degrees from its position
cutting tooth 31 and 41 cutting the outer and inner an~
shown in FIG. 2.
nular portion of the recess 22 in simultaneous progres
FIG. 5 is a cross sectional view taken on the line
40 sion from the top to the bottom of the said recess 22.
5-5 of FIG. 4.
It is essential that each of the cutting teeth 31 and 41
FIG. 6 is a cross sectional view through a trepanned
are over ?fty percent of the width of the annular bottom
work piece with a sharpened trepanning tool embodying
of the trepanned cut or are of a combined width greater
the invention disposed in the trepanned cut indicating
than the annular bottom 222 of the recess 22.
how a trepanning tool of the invention is readily sharp
45
During the aforedescribed cutting operation, the mate
ened.
rial removed from work piece 21 to form the annular
FIG. 7 is a cross sectional view similar to FIG. 6 show
recess 22 is divided into two parts or chip ribbons, the
ing the extent to which a trepanning tool embodying the
cutting tooth 31 removing an outer chip ribbon leaving
invention may be cut away by repeated sharpenings,
thusly providing an indication of the extremely long 50 the tool through the chip slot 32 and the cutting tooth
41 removing an outer chip ribbon leaving the tool
useful life of the improved trepanning tool.
through the chip slot ‘42. Although the chips from the
FIG. 8 is a longitudinal sectional view similar to FIG.
two cutting teeth 31 and 41 ‘have been described as chip
2 showing how a trepanning tool embodying the inven
ribbons, in practice these so-called ribbons easily break up’,
tion is olfset with respect to‘ the central boss and cylin
and, because they each are of less width than the annulus
drical bore of a work piece to accomplish a trepanning 55 of the annular recess 22, they readily leave the trepan
cut to produce accurately and simultaneously a central
ning tool through the chip slots 32 and 42 and at the
boss and a cylindrical bore.
same time provide abundant room for cutting ?uid to
FIG. 9 is a cross sectional view taken on the line
enter and leave the annular recess 22 as it is being
9—9 of FIG. 8.
for-med. The chip slots 32 and ‘42 respectively con
FIG. 10 is a longitudinal sectional view similar to 60 stitute the space between the cutting arms 30 and 40
rotationally ahead of the face of the‘ cutting teeth 31
FIG. 9 showing how a trepanning tool shown in FIGS.
and 41,‘ see FIG. 3.
l-9 inclusive can be formed to provide, for example, a
By reference to FIGS. 2-5 inclusive, it will be ob
shaped rather than a ?at bottom to a trepanned cut, and
served that the cutting teeth 31 and 41 are preferably
a chamfer at the outer edge of the cylindrical wall of the
trepanned cut, all while performing the trepanning opera 65 shaped along spiral-helical curves to provide the neces
sary radial and end clearances between the tool and the
tion.
cut
surfaces of the work piece 21. In other words, each
Referring now to the drawings, and in particular to
cutting tooth 31 and 41 is generated to the desired cross
FIGS. l-9 inclusive, an illustrative embodiment of a
sectional shape advancing along a combination spiral
trepanning tool 20 is disclosed which makes a trepanned 70 helical curve by a combined rotary and translatory mo
cut in a work piece 21, the said out providing an annular
tion selected to keep the generated surface always in a
recess 22 between a cylindrical boss 23 centrally disposed
common plane with the longitudinal axis of the trepan
4
ning‘tool. In the foregoing respect, the cutting tooth 31
of» the trepanning tool 20 illustrating the instant inven
tion is preferably formed in a similar manner to the
cutting tool disclosed in Patent No. 2,556,745 issued on
resharpened trepanning tool 20 in a proper axial offset
position in respect to the work piece 21. This requires
two separate machine adjustments.
First, the trepanning tool 20 must be rotated about
June 12, 1951', to Lukas Zimm'ermanri, the applicant
its own axis to bring the line B—B on a vertical axis.
herein.
This position is illustrated in FIG. 7.
Secondly, the machine slide upon which the trepanning
tool 20 is rotatably mounted is moved along the line
B—B from its position shown in FIG. 7 a distance equal
The cross sectional shape of the cutting tooth 41 of
the said trepanning tool 20 is preferably formed in a
similar manner to the said cutting tooth 31 but reversed
to‘ cause the‘ said tooth 41 to function as a turning tool. 10 to “x,” which is equal to “y,” which movement will bring
Therefore, in the instant invention, the cutting tooth 31
functions‘ similar to a boring tool while the cutting tooth
41 functions similar to a turning tool, the former remov
ing‘ the outer portion 220 of the trepanned cut and the
latter removing the inner portion 221 of the trepanned
the resharpened trepanning tool 20 in its proper work
ing position as shown in FIGS. 8 and 9. In such posi
tion, the sharpened tooth 31 will bore the outer annular
portion of the annular recess 22 while the sharpened
tooth 41 will turn the‘ inner annular portion of the said
cut, both simultaneously as the trepanning tool 20 is'
annular recess 22.
advanced into the work piece 21 and tool 20 or work
Referring now to FIG. 10, it will be observed that,
piece 21 is rotated to provide in e?fect a rotation “R”
by suitably shaping the axial end of the cutting teeth 310’
of the tool 20 with respect to the work piece 21.
and 410 of the trepanning tool 50 disclosed therein, and/
To sharpen a trepanning tool 20, it is ground at the 20 or by suitably forming the cutting arm 30 of the said
cutting faces of the cutting teeth 31 and 41 diametrically
trepanning tool 50 at 301, the annular bottom 520 of
across the diametrical plane “A—A,” and can be re
the annular recess 52 of the work piece 51 and the
sharpened frequently taking away additional tool stock
outer edge 540 of the wall of the cylindrical bore 54
up to the diametrical plane “B—B” leaving only sui?
of the said work piece 51 may be shaped and/or cham
cient stock in each cutting arm 30 and 40 to provide 25 fered respectively. Otherwise, the trepanning tool 50
adequate strength for the trepanning tool 20 to perform
is like and similar to the illustrative embodiment of the
its function without breakage. Accordingly, it is obvious
invention disclosed in FIGS. 1-9 inclusive.
by reference to FIG. 6 that a trepanning tool 20 can be
It is obvious that many changes may be made in the
sharpened a great number of times which assures an
size, shape and arrangement of the various elements of
extremely long tool life. The resharpening is accom 30 a trepanning tool embodying the invention, all without
plished in a manner similar to that employed in sharpen
departing from the spirit and scope of the invention as
de?ned by the appended claims.
in'g conventional circular form tools.
I claim:
It is important to note that the cutting faces of the
cutting teeth 31 and 41 are 180 degrees apart, and, in
1. A cutting tool for performing trepanning operations
resharpening the trepanning tool 20, this 180 degree
having a cutting head bifurcated on its longitudinal axis
angular relationship of cutting faces of the cutting teeth
providing a pair of cutting elements spaced 180 degrees
31 and 41 must be maintained.
apart, said cutting elements being formed on combined
To be assured that a trepanning tool 20 will cut accu
spiral-helical curves each having a cutting tooth with
rately the diameter “a" of the cylindrical bore 24 and the
the face thereof disposed in the direction of cutting rota
diameter “b” of the cylindrical boss 25 as indicated in 40 tion of said cutting tool, one cutting element being formed
FIG. 6, it is necessary that the diametric distance “d”
to cut the outer portion of the trepanning cut spiraling
between the outer cutting edge of the cutting tooth 31
inwardly therefrom, the other cutting element being
and the inner cutting edge of the cutting tooth 41 be equal
formed to cut the inner portion of the trepanning cut
1/2a plus 1/2‘b.
spiraling outwardly therefrom, and the axial ends of said
When applied to the work piece 21, the cutting tooth 45 cutting elements being formed to cut the bottom of the
said trepanning cut.
31 will bore accurately the cylindrical bore 24 while the
cutting tooth 41 will turn accurately the cylindrical boss
2. A cutting tool ‘for performing trepanning operations
23, and both cutting teeth 31 and 41 will cut accurately
comprising a shank and an axially bifurcated head pro
the annular bottom 222' of the annular recess 22.
viding a pair of cutting elements spaced 180 degrees
To maintain the aforementioned performance through 50 apart, said cutting elements being formed on combined
out the life of the trepanning tool, it is essential that
spiral-helical curves each having a cutting tooth disposed
the spiral-helical relief of the two cutting teeth 31 and
on a radial line through the transverse center of said
41 be of precisely the same magnitude.
cutting head and faced in the direction of cutting rota
Referring now to FIG. 6, let it be assumed that, by
tion of said cutting tool, one cutting element being formed
repeated sharpening, the cutting edges of the cutting 55 to provide a cutting tooth ‘for cutting the outer portion
teeth 31 and 41 which were originally located on the
of the annulus of a trepanning cut, the other cutting
element being formed to provide a cutting tooth for
diametrical plane “B-—B.” This, of course, decreases
cutting the inner portion of the annulus of the trepan
the radius vector of the tooth 31 by the distance “x”
ning cut, the spiral helical relief of both cutting teeth
and increases the radius vector of the tooth 41 by the 60 being precisely of the same magnitude, and the axial
distance “y.”
ends of said cutting tool being formed to .cut the bottom
p The combined spiral-helical curves of the cutting teeth
of the said trepanning cut with each cutting element cut
31 and 41 are generated in such a manner that, for any
ing the bottom of said cut in overlapped relationship to
diametrical plane through the longitudinal axis of the
the portion cut by the other.
trepanning tool 20, the increments “x” and “y” will be 05
equal. Therefore, when the cutting teeth 31 and 41 are
References Cited in the ?le of this patent
resharpened so that a 180 degree angular relationship
UNITED STATES PATENTS
of the faces of the said cutting teeth 31 and 41 are main
476,312
Resche _-_ _____________ .._ June 7, 1892
tained, the distance between the radial cutting edges will
70
be maintained at 1/2a plus %b.
FOREIGN PATENTS
After each resharpening of a trepanning tool 20 em
diametrical plane “A——A” have been brought to the
bodying the invention, it is necessary to bring the said
593,622
Great Britain _________ .._ Oct. 22, 1947
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