U.S. patent number RE31,755 [Application Number 06/162,040] was granted by the patent office on 1984-12-04 for tool and chuck for hammer drill.
This patent grant is currently assigned to Robert Bosch GmbH. Invention is credited to Klaus Voss, Karl Wanner.
United States Patent |
RE31,755 |
Wanner , et al. |
December 4, 1984 |
Tool and chuck for hammer drill
Abstract
A hammer drill has a chuck forming a tool receptacle defining a
chuck axis and provided with a tool-holding element radially
displaceable into a position protruding into the tool receptacle.
The tool has a shank defining a tool axis receivable axially in the
receptacle. This shank is formed with a radially outwardly opening
recess closed at both axial ends and shaped to receive the
tool-holding element, and with an axially extending groove separate
from the recess and opening axially at the end of the shank. This
groove has at least one flank extending substantially radially of
the tool axis. A rotary-entrainment formation in the receptacle is
formed with at least one side flatly engageable with the flank for
maximum force transmission and minimum wear.
Inventors: |
Wanner; Karl (Echterdingen,
DE), Voss; Klaus (Stuttgart, DE) |
Assignee: |
Robert Bosch GmbH (Stuttgart,
DE)
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Family
ID: |
5961726 |
Appl.
No.: |
06/162,040 |
Filed: |
June 20, 1980 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
725193 |
Sep 21, 1976 |
04107949 |
Aug 22, 1978 |
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Foreign Application Priority Data
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Nov 14, 1975 [DE] |
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2551125 |
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Current U.S.
Class: |
464/167; 279/75;
279/905 |
Current CPC
Class: |
B25D
17/088 (20130101); B25D 2217/0034 (20130101); Y10T
408/907 (20150115); Y10S 279/905 (20130101); Y10T
279/17752 (20150115); B25D 2217/0042 (20130101) |
Current International
Class: |
B25D
17/08 (20060101); B25D 17/00 (20060101); F16D
003/06 (); B23B 031/06 (); B23B 031/16 () |
Field of
Search: |
;464/167,168,163
;279/1B,19,19.3,19.4,22,30,75,81 ;173/104-111 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2408557 |
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Sep 1975 |
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DE |
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2248914 |
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May 1975 |
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FR |
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278062 |
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Dec 1951 |
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CH |
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Primary Examiner: Lazarus; Ira S.
Attorney, Agent or Firm: Striker; Michael J.
Claims
What is claimed as new and desired to be protected by Letters
Patent is set forth in the appended claims:
1. In a combination with a chuck having a tool receptacle defining
a chuck axis, a rotary and impact tool having a shank defining a
tool axis and receivable in said receptacle; cooperating means on
said shank and said receptacle for retaining said tool in said
receptacle against extraction therefrom while permitting axial
displacement of the tool relative to the receptacle so that the
tool can transmit axial impact to a workpiece; and means separate
from said cooperating means and operative for transmitting torque
between said chuck and said tool, including an axially extending
groove separate and circumferentially spaced from said cooperating
means, said groove being axially open at the end of said shank and
having at least one flank extending substantially radially of said
tool axis, said torque transmitting means further including a
rotary-entrainment formation in said receptacle formed with at
least one side flatly engageable with said flank.
2. The combination defined in claim 1 wherein said groove has a
pair of such flanks both being coplanar with said tool axis.
3. The combination defined in claim 2 wherein said formation has an
axial length substantially equal to the axial length of said
groove.
4. The combination as defined in claim 1, wherein said cooperating
means includes a radially outwardly opening recess formed in said
shank and closed at both axial ends of said recess, and a
tool-holding element radially displaceable into a position
protruding into said receptacle so as to be received into said
recess.
5. The combination defined in claim 4 wherein said shank is of
regular section, said recess extending circumferentially completely
around said shank and through said groove.
6. The combination defined in claim 4 wherein said shank is
generally cylindrical and has a predetermined diameter, said groove
having a radial depth equal to between three-twentieths and
one-quarter of said diameter.
7. The combination defined in claim 4 wherein said groove and said
recess lie on diametrically opposite sides of said tool axis.
8. The combination defined in claim 4 wherein said tool-holding
element has a round inner end and said recess is similarly of
rounded shape complementary to that of said inner end.
9. The combination defined in claim 4 wherein said shank is formed
with two such recesses on diagonally opposite sides and with two
such grooves also on diagonally opposite sides but angularly offset
from said recesses.
10. The combination defined in claim 9 wherein said grooves are
offset angularly relative to said tool axis from said recesses by
between 45.degree. and 90.degree..
11. The combination defined in claim 1 wherein said groove is of
prismatic shape.
12. The combination defined in claim 11 wherein said shank has two
such grooves on diagonally opposite sides.
13. The combination defined in claim 11 wherein said recess is of
part-cylindrical shape and said groove is formed in the base of
said recess.
14. In a power tool, a combination comprising a chuck having a tool
receptacle defining a chuck axis; a rotary and impact tool having a
shank defining a tool axis and being receivable in said receptacle;
cooperating means on said shank and said receptacle for retaining
said tool in said receptacle against extraction therefrom while
permitting axial displacement of the tool relative to the
receptacle so that the tool can transmit axial impact to a
workpiece; and means separate from said cooperating means and
operative for transmitting torque between said chuck and said tool,
including an axially extending groove separate and
circumferentially spaced from said cooperating means, said groove
being axially open at the end of said shank and having at least one
flank extending substantially radially of said tool axis, said
means further including a rotary-entrainment formation in said
receptacle formed with at least one side flatly engageable with
said flank. .Iadd.
15. A rotary and impact tool for the use with a chuck having a tool
receptacle, a first formation in the receptacle and a projection in
the receptacle separate from the first formation, the tool
comprising a shank defining a tool axis; a second formation on said
shank and cooperating with the first formation of the chuck so as
to form together cooperating means for retaining the tool in the
receptacle of the chuck against extraction therefrom while
permitting axial displacement of the tool relative to the
receptacle whereby the tool can transmit axial impact to a
workpiece; and an additional formation on said shank and formed as
an axially extending groove which is separate and circumferentially
spaced from said second formation, said groove being axially open
at the end of said shank and having at least one flank extending
substantially radially of said tool axis so that the projection of
the chuck can engage in said groove and at least one side of the
projection can flatly engage with said one flank, whereby said
groove of said shank and the projection of the chuck together form
means which is separate from the cooperating means and operative
for transmitting torque between the chuck and the tool. .Iaddend.
.Iadd.
16. A rotary and impact tool as defined in claim 15, wherein said
second formation of said shank is arranged so that it is in direct
contact with the first formation of the receptacle of the chuck
without interposition of additional means. .Iaddend. .Iadd.17. A
rotary and impact tool as defined in claim 15, wherein said one
flank of said groove of said shank is arranged so that it is in
direct contact with the projection of the chuck without
interposition of additional means. .Iaddend. .Iadd.18. A rotary and
impact tool as defined in claim 15, wherein said second formation
of said shank is formed as a concave recess which is closed at both
its axial ends. .Iaddend. .Iadd.19. A rotary and impact tool as
defined in claim 15, wherein said second formation of said shank is
formed as a recess having a part-cylindrical cross section and two
part-spherical axial ends. .Iaddend. .Iadd.20. A rotary and impact
tool comprising a shank defining a tool axis; a formation on said
shank allowing limited axial displacement of said shank so that the
tool can transmit axial impact to a workpiece and at the same time
preventing complete axial extraction of said shank from a holding
structure; and an additional formation on said shank and formed as
an axially extending groove which is separate and circumferentially
spaced from said first-mentioned formation, said groove being
axially open at the end of said shank, having at least one flank
extending substantially radially of said tool axis and being
operative for transmitting torque to said shank. .Iaddend.
.Iadd.21. A rotary and impact tool as defined in claim 20, wherein
said first-mentioned formation on said shank is formed as a concave
recess
which is closed at both its axial ends. .Iaddend. .Iadd.22. A
rotary and impact tool as defined in claim 20, wherein said
first-mentioned formation on said shank is formed as a recess
having a part-cylindrical cross section and two part-spherical
axial ends. .Iaddend.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application is related to the commonly assigned and copending
patent application No. 574,715 filed May 5, 1975 (now U.S. Pat. No.
3,995,703) the entire disclosure of which is herewith incorporated
by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a hammer drill. More particularly
this invention concerns .Iadd.a tool, as well as .Iaddend.a chuck
and tool for a hammer drill.
In a hammer drill it is necessary to secure the shank of a drill
bit in the workpiece holder or chuck. The tool is axially
reciprocated and rotated, so that it is necessary to allow at least
limited axial displacement of the tool in the chuck, yet be able to
transmit rotary motion between the chuck and the tool.
Normally the tool is simply formed with a recess that is closed at
both axial ends and of part-cylindrical shape. The chuck has a
normally cylindrical receptacle adapted to receive this shank and
is provided with a radially inwardly engageable tool-securing
element that is movable into a position in the recess. Thus this
element serves not only to prevent the tool from falling axially
out of the chuck, but also serves to transmit force angularly
between the chuck and the tool.
A considerable disadvantage with this system is that the
tool-holding element and the corresponding recess are subjected to
considerable force so that they tend to wear, with the recess
enlarging and the element becoming smaller. After some use,
particularly when the tool is employed to drill holes in masonry
and the like, the fit between the tool and the chuck becomes so
very loose that it is necessary to use a new tool and/or replace
the holding element.
It has been attempted to overcome this disadvantage by replacing
the normally part-spherical end of the element which engages in the
recess with an axially elongated cylindrical member so that a
greater contact surface is obtained. Such an arrangement does
increase the service-life of the combination somewhat but
nonetheless leaves this element and the recess as the most
wear-prone parts of the combination.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide
.Iadd.an improved tool, as well as .Iaddend.an improved chuck and
tool combination.
Another object is the provision of such a .Iadd.tool and
.Iaddend.combination which .[.is.]. .Iadd.are .Iaddend.particularly
useable in a hammer drill, that is in a power tool wherein a drill
bit or the like is rotated and reciprocated axially at the same
time.
These objects are attained according to the present invention in
.[.combination wherein the tool.]. .Iadd.a tool which .Iaddend.has
a recess as described above, and in addition to this recess is
formed with an axially extending groove which opens axially of the
end of this shank and has at least one flank which extends
substantially radially of the tool axis defined by the tool shaft.
The chuck .[.according to this invention.]. .Iadd.for such a tool
.Iaddend.is provided with a rotary-entrainment formation in the
receptacle which is formed with at least one side flatly engageable
with the flank of the groove. Thus the flank of the groove and the
side of the tool engage flatly against each other in surface
contact in a direction exactly perpendicular to the direction that
force must be applied so that wear is reduced to an absolute
minimum. Indeed in such a system it has been found that the tool
normally wears out at its working end long before the shank has
worn noticably.
According to further features of this invention the formation is a
prismatic or polygonal-section ridge integrally formed with the
chuck. This ridge may be of a trapezoidal section and have a pair
of such sides engageable with the corresponding pair of sides of a
trapezoidal-section groove in the tool shank. The formation and the
groove are of approximately the same axial length and each of the
flanks of the grooves lies in a respective plane including a tool
axis.
In accordance with yet another feature of this invention, the
recess, which serves merely in combination with the tool-holding
element to secure the tool in the workpiece, is of round section
shape. It may be formed as a circumferential groove extending
completely around the shank or as a simple recess adapted to
receive the part-spherical end of the tool-holding element.
Two such grooves may be provided in accordance with the present
invention on diametrically opposite sides of the tool shank, and
offset by a predetermined angular distance of between 45.degree.
and 90.degree., preferably 60.degree., from a pair of such recesses
similarly diametrically oppositely formed in the tool shank.
According to yet another feature of this invention the tool shank
is of generally cylindrical shape and has a predetermined diameter.
The groove has a radial depth equal to between 0.15 and 0.25 of
this diameter.
The novel features which are considered as characteristic for the
invention are set forth in particular in the appended claims. The
invention itself, however, both as to its construction and its
method of operation, together with additional objects and
advantages thereof, will be best understood from the following
description of specific embodiments when read in connection with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is an axial section of .[.the combination.]. .Iadd.a tool
and a chuck .Iaddend.according to this invention;
FIG. 2 is a section taken along line II--II of FIG. 1;
FIG. 3 is a side view of a second tool according to this
invention;
FIG. 4 is a section taken along line IV--IV of FIG. 3;
FIG. 5 is a view corresponding to FIG. 3 of a third tool according
to this invention;
FIG. 6 is a section taken along line VI--VI of FIG. 5;
FIG. 7 is a view similar to FIG. 4 of a fourth tool according to
this invention;
FIG. 8 is a section taken on line VIII--VIII of FIG. 7; and
FIGS. 9, 10 and 11 are cross sections through further tool shanks
according to the present invention.
SPECIFIC DESCRIPTION OF PREFERRED EMBODIMENTS
As shown in FIG. 1 a hammer drill has a housing 1 with a spindle 2
defining an axis A and both rotatable about this axis A and
reciprocal limitedly along this axis A. The end of the spindle 2
has a small-diameter hardened-steel extension 2' protruding axially
into the rear end of a cylindrical receptacle or bore 4 formed in a
chuck 3. A tool 6 has a shank 5 defining an axis coaxial with the
axis A and abutting on its rear end against the extension 2'. In
addition the chuck 3 is provided with a pair of diametrically
opposite balls 8 engageable through radially extending holes 8' and
pressable by means of a collar 12' carried on a sleeve 12 into
corresponding recesses 7 in the shank 5. A spring 13 biases the
sleeve 12 and collar 12' forwardly, but when pulled backwardly
these balls 8 can move out of the recesses 7 so as to allow the
tool 6 to be axially withdrawn from the receptacle 4.
As better shown in FIG. 2 the chuck 3 is formed with a pair of
diametrically opposite trapezoidal-section ridges 11 engageable in
corresponding shaped grooves 9 formed in diametrically opposite
sides of the shank 5 at locations 90.degree. offset from the
recesses 7.
The cylindrical shank 5 has a diameter d and the grooves 9 have a
depth t equal to between 0.15 and 0.25 d, preferably 0.20 d. In
this arrangement the diameter d is equal to 10 mm and t is
therefore equal to 2.0 mm.
With the arrangement shown each of the flanks 10 lies in a
respective plane including the axis A so that force transmission
between the ridges .[.10.]. .Iadd.11 .Iaddend.and the grooves 9 is
effected along surfaces extending perfectly perpendicular to the
direction that the force is exerted. In addition FIG. 1 shows how
the groove 9 is of the same axial length as the ridge 11, insuring
a long surface for force transmission between these two
formations.
The arrangement shown in FIGS. 3 and 4 is for use with workpieces
having shanks 5 with a diameter d equal to more than 10 mm. In this
arrangement the recess 7 is identical to that shown in FIGS. 1 and
2, but on the opposite side there is formed a force-transmitting
groove 19 with adjacent its base planar flanks 20 identical in
function to the flanks 10, but also formed with part-cylindrical
surfaces 21 of the same radius of curvature as the recess 7. The
dpeth t of the groove 19 is once again equal to 0.2 d. This
arrangement can use a ball as shown in FIGS. 1 and 2 or a
cylindrical roller with ball-shaped ends to secure it in the chuck
3.
The advantage of the arrangement shown in FIGS. 3 and 4 is that the
edges of the recess 19 are substantially less sensitive to damage,
so that the corresponding formation 11 will always fit snugly into
the groove 19 flatly against the faces 20 thereof.
In FIGS. 5 and 6 a shank 35 is shown which is formed with a pair of
diametrically opposite part-cylindrical recesses 27 centered on
axes spaced from the shank 25 and lying in a plane perpendicular to
the axis A thereof. It is also possible in this arrangement to form
the grooves 9 similarly to the grooves 19 of FIGS. 3 and 4.
In FIG. 7 a tool shank 35 is shown having a part-cylindrical
section circumferential groove 37 adapted to receive the balls 8
and extending completely around the shank 35. This groove 37 is of
a depth less than the depth of the grooves 9. This arrangement is,
once again, provided with two torque-transmitting grooves 9 of
trapezoidal section. Such an arrangement is able to transmit
considerable rotational forces between the chuck and the shank 35.
It is also possible in this arrangement to provide two further
grooves 9 offset by 90.degree. to the grooves 9 shown in FIG. 4 so
that four formations can be used to transmit force between the
chuck 3 and the shank 35.
The arrangement shown in FIG. 9 is identical to that shown in FIGS.
3 and 4 except that here surfaces 21 are provided which are planar
rather than part-cylindrical.
In FIG. 10 a shank 45 is shown which has on one side a recess
identical to the recess 7 and on the other side a recess 39 formed
as two trapezoidal-section grooves having outer flanks 40 and
separated by an intermediate ridge 42 that does not extend all the
way out to the outer circumference of the shank 45. In addition,
the flanks 40 are beveled off at 41 much as shown in FIG. 9 so that
slight damage to the outer part of the shank 45 will not prevent a
correspondingly shaped ridge from fitting into the double groove 39
snugly in contact with the intermediate ridge 42 and flanks 40
thereof.
Finally, FIG. 11 shows a shank 55 which is adapted to be rotated in
a direction 56. This shank 55 is formed with a pair of
diametrically opposite recesses 7 and a pair of diametrically
opposite recesses 19 identical to those shown in FIGS. 3 and 4 and
having surfaces 57 corresponding to the surface 20 in FIGS. 3 and
4. In this arrangement, however, each of the grooves 19 lies in the
direction of rotation 56 at an angle .alpha. offset from the
corresponding recess 7. This angle .alpha. is equal to 60.degree.
and ensures that relatively wide webs are provided on the bearing
sides of the grooves 19 for maximum force transmission between the
chuck 3 and the shank 55. Such an arrangement has been found to
have an extremely long service life and to be able to transmit
enormous torque.
With the tools according to the present invention it is therefore
possible to obtain a service life which is a multiple of the
service life normally obtained by bits in a hammer drill. Indeed it
is possible to use the tool until its working end is completely
worn away, whereas in normal situations the shank often wore out
before the working tip did.
It will be understood that each of the elements described above, or
two or more together, may also find a useful application in other
types of structure differing from the types described above.
While the invention has been illustrated and described as embodied
in a hammer-drill arrangement, it is not intended to be limited to
the details shown, since various modifications and structural
changes may be made without departing in any way from the spirit of
the present invention.
Without further analysis, the foregoing will so fully reveal the
gist of the present invention that others can, by applying current
knowledge, readily adapt it for various applications without
omitting features that, from the standpoint of prior art, fairly
constitute essential characteristics of the generic or specific
aspects of this invention.
* * * * *