U.S. patent application number 10/493921 was filed with the patent office on 2005-05-05 for drilling and/or hammering tool.
Invention is credited to Bernhart, Ralf, Buchholz, Achim, Herting, Rainer.
Application Number | 20050093251 10/493921 |
Document ID | / |
Family ID | 26246703 |
Filed Date | 2005-05-05 |
United States Patent
Application |
20050093251 |
Kind Code |
A1 |
Buchholz, Achim ; et
al. |
May 5, 2005 |
Drilling and/or hammering tool
Abstract
A drilling and/or hammering tool which includes a hollow spindle
(1) and a tool holder (10) that can be attached to an end (18) of
the spindle and removed therefrom. The toll holder comprises a tool
holder body (14) which can be fitted within the end of the spindle
and releaseably locked therein by means of at least one locking
element (32) and a locking ring (42) for releasably holding the or
each locking element in a locked position in which the locking
element(s) lock(s) the tool holder to the spindle. The tool holder
(10) comprises a manually actuable sleeve (40) for rotating the
locking ring (42) in a first direction and for rotating the tool
holder body (14) in a second opposite direction, and resilient
means (62) for urging the tool holder body to follow the movement
of the locking ring in the first direction and the locking ring to
follow the movement of the tool holder body in the second
direction. The resilient means urges the locking ring and the tool
holder body into relative rotational positions in which the locking
ring (42) holds the or each locking element in the locked position.
The locking ring (42) has an internal radius that varies along its
circumference so that rotation of the locking ring about the axis
of the tool holder body will move it between a locking position in
which it causes the or each locking element (32) to retain the toll
holder body in the spindle, and a release position in which it will
allow the or each locking element to move radially to release the
tool holder body.
Inventors: |
Buchholz, Achim; (Limburg,
DE) ; Bernhart, Ralf; (Idstein, DE) ; Herting,
Rainer; (Langenhahn, DE) |
Correspondence
Address: |
Michael P Leary
The Black & Decker Corporation
Group Patent Counsel
701 East Joppa Road TW199
Towson
MD
21286
US
|
Family ID: |
26246703 |
Appl. No.: |
10/493921 |
Filed: |
December 7, 2004 |
PCT Filed: |
October 25, 2002 |
PCT NO: |
PCT/EP02/11929 |
Current U.S.
Class: |
279/19 |
Current CPC
Class: |
Y10T 279/17042 20150115;
Y10S 403/11 20130101; Y10T 279/17068 20150115; B25D 17/08 20130101;
Y10T 403/20 20150115; Y10T 403/7047 20150115; Y10T 279/17094
20150115; B25D 2217/0042 20130101 |
Class at
Publication: |
279/019 |
International
Class: |
B23B 031/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 26, 2001 |
GB |
0125749.2 |
May 16, 2002 |
GB |
0211184.7 |
Claims
1. A drilling and/or hammering tool which includes a hollow spindle
(1) and a tool holder (10) that can be attached to an end (18) of
the spindle and removed therefrom, the tool holder comprising: a
tool holder body (14) which can be fitted within the end of the
spindle and releaseably locked therein by means of at least one
locking element (32); and a locking ring (42) for releasably
holding the or each locking element in a locked position in which
the locking element(s) lock(s) the tool holder to the spindle,
characterised in that the tool holder (10) comprises a manually
actuable sleeve (40) for rotating the locking ring (42) in a first
direction and for rotating the tool holder body (14) in a second
opposite direction, and resilient means (62) for urging the tool
holder body to follow the movement of the locking ring in the first
direction and the locking ring to follow the movement of the tool
holder body in the second direction, said resilient means urging
the locking ring and the tool holder body into relative rotational
positions in which the locking ring (42) holds the or each locking
element in the locked position.
2. A tool according to claim 1 wherein the locking ring (42) is
rotated by the sleeve in the first direction to release the tool
holder (10) from the spindle and the tool holder body (10) is
rotated by the sleeve in the second direction to lock the tool
holder to the spindle.
3. A tool according to claim 1 or claim 2 wherein the locking
elements are mounted at the end (18) of the spindle so as to be
radially shiftable with respect to the longitudinal axis of the
spindle.
4. A tool according to any one of the preceding claims wherein the
manually actuable sleeve (40) rotates the tool holder body via a
member (44) non-rotatably mounted on the tool holder body (14).
5. A tool according to any one of the preceding claims wherein the
manually actuable sleeve (40) is mounted for limited rotation with
respect to the locking ring (42) and the tool holder body (14).
6. A tool according to any one of the preceding claims wherein the
manually actuable sleeve (40) is mounted for limited rotation in
the first direction with respect to the tool holder body (14).
7. A tool according to any one of the preceding claims wherein the
manually actuable sleeve (40) is mounted for limited rotation in
the second direction with respect to the locking ring (42).
8. A tool according to any one of the preceding claims wherein the
resilient means is a coil spring (62) with a first end fixed to the
locking ring (42) and a second end fixed with respect to the tool
holder body (14).
9. A tool according to claim 8 when dependent on claim 4 wherein
the second end of the coil spring is fixed to the member (44).
10. A tool according to any one of the preceding claims wherein the
tool holder body has a recess (38) for each locking element and the
locking ring (42) has a recess for receiving each locking element
(32), which locking ring recess has a deep portion (70) and a
shallow portion (72), arranged such that when the deep portion (70)
is in register with a locking element the locking element can move
out of the corresponding tool holder recess and the tool holder can
be removed from or fitted to the spindle (18) and when a shallow
portion (72) is in register with a locking element the locking
element is locked in the corresponding tool holder recess and the
tool holder is fixed to the spindle.
11. A tool according to claim 10 wherein each tool holder recesses
(38) is formed in a radially outwardly facing surface of the tool
holder and each locking ring recess is formed in a radially
inwardly facing surface of the locking ring.
12. A tool as claimed in claim 10 or 11, wherein the tool holder
body (14) can be inserted in the end of the spindle so that the or
each locking element (32) is in a radially outermost position and
is received in a deep portion (70) of the locking ring, and manual
rotation of the manually actuable sleeve (40) in the second
direction will cause the tool holder body (14) to rotate with
respect to the spindle but the locking ring (42) will be prevented
from rotating with respect to the spindle by means of the or each
locking element until the or each tool holder recess (38) is in
circumferential register with a locking element, whereupon the or
each locking element will move radially inwardly into its recess
and allow the locking ring to rotate under the bias of the
resilient means (62) into its locking position.
13. A tool as claimed in any one of claim 10 to 12, wherein, when
the tool holder (10) is inserted in the end of the spindle and the
locking ring (42) is in its locking position, manual rotation of
the manually actuable sleeve (40) about the spindle in the first
direction will cause the locking ring to rotate together with the
sleeve against the bias of the resilient means (62) until the or
each locking element is in register with a deep portion (70) of the
locking ring, whereupon the or each locking element will move
radially outwardly into its deep portion to allow removal of the
tool holder.
14. A tool as claimed in any one of the preceding claims, wherein
the tool holder includes an arrangement for holding a tool or bit
therein, the tool holder including a part (26) that is moved
manually in an axial direction to release the tool or bit.
15. A tool according to any one of the preceding claims wherein the
first direction is clockwise and the second direction is
anti-clockwise.
16. A tool holder (10) that can be attached to an end (18) of a
spindle of a drilling and/or hammering tool and removed therefrom,
the tool holder comprising: a tool holder body (14) which can be
fitted to the end of the spindle and releaseably locked thereto by
means of at least one locking element (32); and a locking ring (42)
for releasably holding the or each locking element in a locked
position in which the locking element(s) lock(s) the tool holder to
the spindle, characterised in that the tool holder (10) comprises a
manually actuable sleeve (40) for rotating the locking ring (42) in
a first direction and rotating the tool holder body (14) in a
second opposite direction, and resilient means (62) for urging the
tool holder body to follow the movement of the locking ring in the
first direction and the locking ring to follow the movement of the
tool holder body in the second direction, said resilient means
urging the locking ring and the tool holder body into relative
rotational positions in which the locking ring (42) holds the or
each locking element in the locked position.
17. A drilling and/or hammering tool which includes a hollow
spindle (1) and a tool holder (10) that can be attached to an end
(18) of the spindle and removed therefrom, the tool holder having a
tool holder body (14) that can be inserted into the end of the
spindle and retained therein by means of at least one locking
element (32) that is movable in a radial direction to retain, or to
allow release of, the tool holder body, and a locking ring (42) for
holding the or each locking element in a position that retains the
tool holder body in the spindle, characterised in that the locking
ring has an internal radius that varies along its circumference so
that rotation of the locking ring about the axis of the tool holder
body will move it between a locking position in which it causes the
or each locking element to retain the tool holder body in the
spindle, and a release position in which it will allow the or each
locking element to move radially to release the tool holder
body.
18. A tool as claimed in claim 17, wherein the or each locking
element (32) is located in an aperture (34) in one of the spindle
or the tool holder body, and will engage a depression (38) in the
other of the spindle or the tool holder body to retain the tool
holder body (14) in the spindle, so that the tool holder body can
be retained in the spindle only when the tool holder body is in a
defined orientation with respect to the axis of the spindle.
19. A tool as claimed in claim 18, wherein the or each locking
element (32) is located in an aperture (34) in the spindle, and
will engage a depression (38) in the tool holder body when it is in
its radially innermost position to retain the tool holder on the
spindle.
20. A tool as claimed in claim 18 or 19, wherein the tool holder
includes a manually operable sleeve (40) that is associated with
the locking ring (42) to enable a user to rotate the locking ring
between the locking position and the release position, the locking
ring having a region of relatively large internal radius forming a
pocket (70) that can receive a locking element when the element is
in its radially outermost position (to allow release of the tool
holder body), and a region (72) of relatively small internal radius
that can receive the locking element only when the locking element
is in a radially inner position in which it engages its depression
(38).
21. A tool as claimed in any one of claims 17 to 20, wherein the
locking ring (42) is biased with respect to the tool holder body
into its locking position.
22. A tool as claimed in any one of claims 20 or 21, wherein the
manually operable sleeve (40) is rotatable with respect to the
locking ring to a limited extent.
23. A tool as claimed in claim 22, wherein the manually operable
sleeve (40) is rotatable with respect to the tool holder body to a
limited extent, and the locking ring is held in its locking
position against the bias by means of the manually operable
sleeve.
24. A tool as claimed in claim 23, wherein the tool holder body
(14) can be inserted in the end of the spindle so that the or each
locking element (32) is in its radially outermost position and is
received in a pocket (70) of the locking ring, and manual rotation
of the sleeve (40) in one sense will cause the tool holder body
(14) to rotate with respect to the spindle but the locking ring
(42) will be prevented from rotating with respect to the spindle by
means of the or each locking element until the or each depression
(38) is in circumferential register with a locking element,
whereupon the or each locking element will move radially inwardly
into its depression and allow the locking ring to rotate under the
bias into its locking position.
25. A tool as claimed in claim 24, wherein, when the tool holder
(10) is inserted in the end of the spindle and the locking ring
(42) is in its locking position, manual rotation of the sleeve (40)
about the spindle in the opposite sense will cause the locking ring
to rotate together with the sleeve against the bias until the or
each locking element is in register with a pocket (70) of the
locking ring, whereupon the or each locking element will move
radially outwardly into its pocket to allow removal of the tool
holder.
26. A tool as claimed in any one of claims 17 to 25, wherein the
tool holder includes an arrangement for holding a tool therein, the
tool holder including a part (26) that is moved manually in an
axial direction to release the tool.
27. A tool holder (10) that can be attached to an end of a spindle
(1) of a drilling and/or hammering tool and removed therefrom, the
tool holder having a tool holder body (14) that can be inserted
into the end of the spindle and retained therein by means of at
least one locking element (32) that is movable in a radial
direction to retain, or to allow release of, the tool holder body,
and a locking ring (42) for holding the or each locking element in
a position that retains the tool holder body in the spindle,
characterised in that the locking ring (42) has an internal radius
that varies along its circumference so that rotation of the locking
ring about the axis of the tool holder body will move it between a
locking position in which it causes the or each locking element to
retain the tool holder body in the spindle, and a release position
in which it will allow the or each locking element to move radially
to release the tool holder body.
28. A tool holder for a drilling and/or hammering tool comprising a
manually actuable sleeve (40) wherein components of the tool holder
are held within the sleeve by a snap ring (100) which snap ring is
fitted within the sleeve, characterised in that the snap ring has
at least one resilient arm (102) and the sleeve has a corresponding
number of through holes (105) which extend to a radially outwardly
facing surface of the sleeve, arranged such that the or each arm is
engageable with a corresponding through hole in a snap fit, and
each arm and through hole cooperate so that the portion (104) of
the or each arm which can be viewed from the radially outwardly
facing surface of the sleeve appears in the shape of a symbol.
29. A tool holder according to claim 28 wherein at least the
radially outermost part of the or each through hole (105) is formed
in the shape of the symbol.
30. A tool holder according to claim 29 wherein the radially
outermost portion of the or each arm (104) is formed in the shape
if the symbol to fit the corresponding through hole.
31. A tool holder according to claim 28 wherein the radially
outermost portion (104) of the or each arm extending through the
corresponding through hole is in the shape of the symbol.
32. A tool holder according to any one of claims 28 to 31 wherein
the or each resilient arm (102) is formed with a latch element
(104) in the shape of the symbol and the latch element is received
in a snap fit within a correspondingly shaped through hole
(105).
33. A tool holder according to any one of claims 28 to 32 wherein
the symbol is an arrow designating the direction in which the
manually actuable sleeve can be moved.
34. A tool holder according to any one of claims 28 to 33 wherein
the manually actuable sleeve is actuable to fit and/or remove a
tool or bit from the tool holder.
35. A tool holder according to any one of claims 28 to 33 wherein
the manually actuable sleeve is actuable to fit and/or remove the
tool holder form the drilling and/or hammering tool.
Description
[0001] This invention relates to drilling and or hammering tools,
and especially to hammers and rotary hammers, and to tool holders
for use with such tools.
[0002] Such tools typically include a spindle that may be rotatably
driven by means of a motor, and a hammer mechanism, for example an
air-cushion hammer mechanism, for repeatedly striking a tool that
is held by the hammer. The shank of a tool such as a drill bit or
chisel bit is held in the tool by means of a tool holder so that
the tool can slide axially in the tool holder by a few centimetres
under the action of the hammer mechanism. In one well known design,
sold under the designation SDS Plus, the tool shank has a pair of
open-ended grooves for receiving splines in the tool holder for
rotating the tool, and a pair of closed-ended recesses for
receiving locking elements in the tool holder that limit the extent
of axial movement of the tool in the tool holder. The tool holder
can be manually manipulated by the operator, for example by means
of axially slidable parts, in order to hold the tool therein and to
release the tool therefrom.
[0003] In addition, the tool holder itself often will need to be
capable of being released from the spindle in order to allow it to
be changed, for example when a different type of tool is to be held
in the hammer. In this case the tool holder body or the spindle is
provided with one or more locking elements, for example locking
balls, that are movable in a radial direction (with respect to the
axis of the spindle) to retain the tool holder body on the spindle,
or to allow release of the tool holder body therefrom.
[0004] While the tool holder body is normally located around the
external surface of the spindle of the hammer, it has been
proposed, for example in GB-A-2,313,566 (corresponding to DE-A-196
21 610) and in U.S. Pat. No. 5,437,465, for the tool holder body to
be inserted into the end of the spindle. Such designs have the
advantage that the length of the tool can be significantly reduced
since the bore of the tool holder that receives the tool shank, and
the bore of the spindle may be allowed to overlap axially. In the
previous designs in which the tool holder was located around the
exterior of the spindle, the bore of the tool holder could only
start at a position beyond the front end of the spindle.
[0005] These designs of tool holder suffer from a number of
disadvantages, however. For example, with the tool holder described
in GB-A-2,313,566, it can be difficult for the user to find the
correct axial orientation of the tool holder on the spindle in
order to lock the tool holder thereon, that is to say, it can be
difficult to ensure that the locking elements located on the
spindle are in circumferential alignment with corresponding
elements on the tool holder for receiving them. In other cases,
axial movement of parts of the tool holder in order to release it
from the spindle can cause difficulties where axial movement of
parts of the tool holder is required to release or retain the tool
shank in the tool holder. For example, where a ring or skirt on the
tool holder must be moved axially forwards to release it from the
spindle, the user will often grasp the tool holder along its axis
with their hand, and squeeze their hand to release the tool holder
(thereby applying a Newtonian reaction force on the front end of
the tool holder with the palm of his hand). This may cause the tool
holder to unlock the tool shank held therein during removal of the
tool holder, so that, when the tool holder is replaced on the
spindle, the tool is ejected out of the tool holder as soon as the
hammer is actuated. Alternatively, it is possible for the tool
holder to be inserted incorrectly so that the tool holder is
ejected when the hammer is actuated. In the case of the arrangement
described in U.S. Pat. No. 5,437,465 on the other hand, in which a
ring must be moved axially rearwardly in order to remove the tool
holder from the spindle, removal of the tool holder necessitates
the operator using both his hands for the purpose.
[0006] According to a first aspect of the present invention there
is provided a hammering and/or drilling tool which includes a
hollow spindle and a tool holder that can be attached to an end of
the spindle and removed therefrom, the tool holder comprising:
[0007] a tool holder body which can be fitted within the end of the
spindle and releaseably locked therein by means of at least one
locking element; and
[0008] a locking ring for releasably holding the or each locking
element in a locked position in which the locking element(s)
lock(s) the tool holder to the spindle,
[0009] characterised in that the tool holder comprises a manually
actuable sleeve for rotating the locking ring in a first direction
and for rotating the tool holder body in a second opposite
direction, and resilient means for urging the tool holder body to
follow the movement of the locking ring in the first direction and
the locking ring to follow the movement of the tool holder body in
the second direction, said resilient means urging the locking ring
and the tool holder body into relative rotational positions in
which the locking ring holds the or each locking element in the
locked position.
[0010] This tool holder locking and release arrangement reliably
fixes the tool holder to the spindle and enables quick and easy
removal of the tool holder from the spindle and quick and easy
replacement of the or an alternative tool holder to the spindle.
Also, it is relatively easy to find the correct starting rotational
positioning of the tool holder on the spindle in the same manual
operation as rotating the manually actuable sleeve to fix the tool
holder onto the spindle.
[0011] In one embodiment the locking ring may be rotated by the
sleeve in a first, preferably clockwise, direction to release the
tool holder from the spindle and the tool holder body may be
rotated by the sleeve in the second opposite, preferably
anti-clockwise, direction to lock the tool holder to the spindle.
The locking elements may be mounted at the end of the spindle so as
to be radially shiftable. The manually actuable sleeve may rotate
the tool holder body via a member non-rotatably mounted on the tool
holder body.
[0012] The manually actuable sleeve may be mounted for limited
rotation with respect to the locking ring and the tool holder body.
In particular the manually actuable sleeve may be mounted for
limited rotation in the first direction with respect to the tool
holder body and/or may be mounted for limited rotation in the
second direction with respect to the locking ring.
[0013] The resilient means may be a coil spring with a first end
fixed to the locking ring and a second end fixed to the member.
[0014] In one embodiment of the first aspect of the present
invention the tool holder portion may have a recess for each
locking element and the locking ring may have a recess for
receiving each locking element, which locking ring recess has a
deep portion and a shallow portion, arranged such that when the
deep portion is in register with a locking element the locking
element can move out of the tool holder recess and the tool holder
can be removed from or fitted to the spindle and when a shallow
portion is in register with a locking element the locking element
is locked in the corresponding tool holder recess and the tool
holder is fixed to the spindle. Each tool holder recesses may be
formed in a radially outwardly facing surface of the tool holder
and each locking ring recess may be formed in a radially inwardly
facing surface of the locking ring.
[0015] The first aspect of the present invention also provides a
tool holder that can be attached to an end of a spindle of a
drilling and/or hammering tool and removed therefrom, the tool
holder comprising:
[0016] a tool holder body which can be fitted to the end of the
spindle and releaseably locked thereto by means of at least one
locking element; and
[0017] a locking ring for releasably holding the or each locking
element in a locked position in which the locking element(s)
lock(s) the tool holder to the spindle,
[0018] characterised in that the tool holder comprises a manually
actuable sleeve for rotating the locking ring in a first direction
and rotating the tool holder body in a second opposite direction,
and resilient means for urging the tool holder body to follow the
movement of the locking ring in the first direction and the locking
ring to follow the movement of the tool holder body in the second
direction, said resilient means urging the locking ring and the
tool holder body into relative rotational positions in which the
locking ring holds the or each locking element in the locked
position.
[0019] The tool holder according to the first aspect of the present
invention may have the subsidiary features discussed above in
relation to the hammering and/or drilling tool according to the
first aspect of the present invention.
[0020] A second aspect of the drilling and/or hammering tool
according to the present invention is characterised in that the
locking ring has an internal radius that varies along its
circumference so that rotation of the locking ring about the axis
of the tool holder body will move it between a locking position in
which it causes the or each locking element to retain the tool
holder body in the spindle, and a release position in which it will
allow the or each locking element to move radially to release the
tool holder body.
[0021] Thus, since locking of the tool holder involves rotation of
the locking ring, it is relatively easy to find the correct angular
orientation of the tool holder about the spindle in the same manual
operation. In addition, it is relatively easy to arrange for
movement of the various parts of the tool holder for unlocking the
tool from the tool holder and for releasing the tool holder from
the spindle to occur in orthogonal directions so that the two
operations will not interfere with each other.
[0022] The or each locking element will normally be located in an
aperture in one of the spindle or the tool holder body, and will
engage a depression in the other of the spindle or the tool holder
body to retain the tool holder body in the spindle, so that the
tool holder body can be retained in the spindle only when the tool
holder body is in a defined orientation with respect to the axis of
the spindle. In most cases, the or each locking element will be
located in an aperture in the spindle, and will engage a depression
in the tool holder body (inserted therein) when it is in its
radially innermost position to retain the tool holder on the
spindle.
[0023] The tool holder may include a manually operable sleeve that
is associated with the locking ring in order to enable a user to
rotate the locking ring between the locking position and the
release position. The locking ring may have, in this case, a region
of relatively large internal radius forming a pocket that can
receive a locking element when the element is in its radially
outermost position (to allow release of the tool holder body), and
a region of relatively small internal radius that can receive the
locking element only when the locking element is in a radially
inner position in which it engages its depression. In this
arrangement, the locking ring may be biased (usually spring biased)
with respect to the tool holder body into its locking position.
Thus, for instance, whether or not the tool holder is located on
the spindle, the locking ring may be biased so that the region(s)
of the locking ring of relatively small radius is in
circumferential register with the depression(s) in the tool holder
body that receive the locking element(s).
[0024] The second aspect of the present invention also provides a
tool holder that can be attached to an end of a spindle of a
drilling and/or hammering tool and removed therefrom, the tool
holder having a tool holder body that can be inserted into the end
of the spindle and retained therein by means of at least one
locking element that is movable in a radial direction to retain, or
to allow release of, the tool holder body, and a locking ring for
holding the or each locking element in a position that retains the
tool holder body in the spindle, characterised in that the locking
ring has an internal radius that varies along its circumference so
that rotation of the locking ring about the axis of the tool holder
body will move it between a locking position in which it causes the
or each locking element to retain the tool holder body in the
spindle, and a release position in which it will allow the or each
locking element to move radially to release the tool holder
body.
[0025] The tool holder according to the second aspect of the
present invention may have the subsidiary features discussed above
in relation to the hammering and/or drilling tool according to the
second aspect of the present invention.
[0026] As discussed above, in relation to both aspects of the
present invention the manually operable sleeve may be rotatable
with respect to the locking ring to a limited extent, and also with
respect to the tool holder body to a limited extent. Thus, the
locking ring can be held in its locking position in this case (or
more accurately, the locking ring and the tool holder body are held
with respect to one another so that the locking ring is in its
locking position) against the spring bias by means of the manually
operable sleeve, which can be provided with some form of detent to
limit further rotation. Rotation of the manually operable sleeve in
one sense (either clockwise or anticlockwise) may be arranged to
cause corresponding rotation of the tool holder body but can allow
the locking ring to remain stationary (with respect to the
spindle), while rotation of the manually operable sleeve in the
opposite sense may be arranged to require corresponding rotation of
the locking ring but can allow the tool holder body to remain
stationary. In this arrangement, the tool holder body can be
inserted in the end of the spindle so that the or each locking
element is in its radially outermost position and is received in a
pocket of the locking ring, and manual rotation of the sleeve in
one sense will cause the tool holder body to rotate with respect to
the spindle but the locking ring will be prevented from rotating
with respect to the spindle by means of the or each locking element
until the or each depression is in circumferential register with a
locking element, whereupon the or each locking element will move
radially inwardly into its depression and allow the locking ring to
rotate under the bias into its locking position. This rotation of
the locking ring will normally be accompanied by a clear audible
click that will signal to the operator that the tool holder is
correctly engaged with the spindle in its locked state. In order to
remove the tool holder from the spindle, the sleeve may be manually
rotated about the spindle in the opposite sense which will cause
the locking ring to rotate together with the sleeve against the
spring bias until the or each locking element is in register with a
pocket of the locking ring, whereupon the or each locking element
will move radially outwardly into its pocket to allow removal of
the tool holder.
[0027] Although the tool holder may, in principle, be arranged so
that it can be released from the spindle by rotation of the locking
ring and/or the sleeve in either the clockwise or anti-clockwise
direction, it is preferred for the tool holder to be released from
the spindle if the locking ring and/or the sleeve is rotated in the
clockwise direction (viewed forwardly along the axis of the tool
holder body) only. This is because rotary hammers are designed for
the tool, and therefore the tool holder, to rotate in a clockwise
direction. Therefore, if the sleeve accidentally brushes against a
wall or other stationary object during operation, the wall or other
object will exert a torque on the sleeve in the anti-clockwise
direction (with respect to the rest of the tool holder) and so
maintain the tool holder locked in the hammer spindle.
[0028] One form of hammer and tool holder in accordance with the
present invention will now be described by way of example, with
reference to the accompanying drawings, in which:
[0029] FIG. 1 is a sectional elevation along the common axis of the
spindle and tool holder of a hammer and tool holder according to
the invention;
[0030] FIG. 2 is an exploded perspective view of the tool holder
and part of the spindle shown in FIG. 1;
[0031] FIG. 3 is a sectional elevation along the common axis of the
spindle and modified tool holder according to the invention;
and
[0032] FIG. 4 is a perspective view of the manually operated sleeve
of the modified tool holder of FIG. 4.
[0033] Referring to the accompanying drawings, a hammer that may be
employed in a combination rotary hammer mode, includes a spindle 1
that is provided with an air-cushion hammer mechanism comprising a
piston 2, that is caused to reciprocate within the spindle by a
swash or wobble mechanism 4 driven by a motor (not shown).
Reciprocating motion of the piston causes a ram 6 to reciprocate,
which strikes a beatpiece 8. The beatpiece 8 strikes the shank of a
drill or chisel bit (not shown) that is held in the bore of a tool
holder 10 in known manner.
[0034] The hammer includes a removable tool holder 10 for holding
the shank of a bit, for example a hammer drill bit or a chipping
bit. The tool holder 10 as shown is designed to hold a bit that has
a pair of closed-end elongate recesses for receiving a locking
element for retaining the bit in the tool holder while allowing
some degree of axial movement, and a pair of open-ended grooves for
receiving rotary driving splines 12, such bits being of a design
referred to as "SDS Plus", but tool holders for other designs such
as SDS Max, hex shank etc. may also be employed. The tool holder
includes a hollow, generally cylindrical tool holder body 14 that
has a rearward end 16 that can be inserted into the forward end 18
of the hammer spindle 1. A locking ball 20 for retaining the bit in
the tool holder 10 is located in an elongate aperture 22 in the
tool holder body 14, and is held in a position in which it extends
into the bore of the tool holder body 14 (and into the recess of
any bit held therein) by means of locking ring 24. The locking ring
24 is located in an axially slidable release sleeve 26 which can be
moved rearwardly against the bias of a spring 28 to allow the
locking ball 20 to move radially outwardly into recess 30 in order
to allow removal of the bit.
[0035] The tool holder body 14 is held in the spindle 1 by means of
four locking balls 32 located in apertures 34 in the spindle wall.
The apertures 34 are slightly tapered in order to prevent the balls
falling into the bore of the spindle 1, and the balls are held in
the apertures by means of a snap ring 36. The locking balls 32 can
move to a limited extent in the radial direction between a radially
outermost position which allows attachment and removal of the tool
holder 10, and a radially innermost position in which the tool
holder is retained on the spindle. The tool holder body 14 has four
depressions 38 in its outer surface for receiving the locking balls
32 when the tool holder 10 is retained on the spindle.
[0036] The tool holder 10 is provided with a manually operable
sleeve 40 that can be rotated about the tool holder body 14 to a
limited extent, and which houses a locking ring 42 that is
positioned about the locking balls 32, and is held in the sleeve 40
by a radially compressed snap ring 43. The sleeve 40 also houses an
annular plate 44 (shown partially cut-away in FIG. 2 to show its
flanged periphery 45). The locking ring 42 has four peripheral
projections 46 that can abut internal shoulders 48 in the sleeve 40
formed by portions 50 of greater wall thickness in order to limit
the extent to which the locking ring can rotate with respect to the
sleeve. In a similar fashion, the annular plate 44 has a pair of
projections 52 in its periphery that can abut further internal
shoulders 54 in the sleeve 40 to limit the extent to which the
annular plate can rotate with respect to the sleeve. The annular
plate 44 has a central aperture 56 to enable it to be located about
the tool holder body 14, the aperture 56 having a flat 58 that
cooperates with a flattened region 60 of the tool holder body 14 in
order to prevent rotation of the annular plate 44 about the tool
holder body. The annular plate 44 and the locking ring 42 are
connected to each other by means of a helical spring 62, one end of
which is located in a hole 64 in the annular plate, and the other
end of which rests against one of the projections 46 on the locking
ring. The spring 62 biases the annular plate 44 and the locking
ring 42 to the limit of their rotation within the sleeve 40, that
is to say, so that the projections 46 and 52 thereon abut the
internal shoulders 48 and 54 in the sleeve, and so that the locking
ring 42 and the tool holder body 14 can only be rotated with
respect to the sleeve against the bias of the spring 62.
[0037] The locking ring 42 has an irregular inner surface having
four relatively thick (i.e. of relatively small internal radius)
regions 66 separated by four recesses 68. The recesses 68
themselves each have one portion 70 that is relatively deep and an
adjacent portion 72 that is relatively shallow. The portions 70 of
the recesses that are relatively deep provide pockets that can
receive the locking balls 32 even when they are in their radially
outermost position for allowing attachment and removal of the tool
holder 10, but the relatively shallow portions 72 of the recesses
68 can receive the locking balls 32 only when they are in their
radially innermost position. The relatively thick regions 66 cannot
receive the locking balls 32 whatever position they are in.
[0038] The sleeve 40, annular plate 44, locking ring 42 and tool
holder body 14 are arranged so that the spring 62 biases the
locking ring to a position in which the relatively shallow portions
72 of the recesses 68 are in circumferential register with the
depressions 38 in the tool holder body, and so that the locking
ring can be rotated by a maximum of about 45.degree. until the
pockets 70 are in register with the depressions 38.
[0039] In order to install the tool holder 10 on the spindle 1 of
the hammer, it is simply pushed onto the end 18 of the spindle so
that the end 16 of the tool holder body 14 is located within the
bore of the spindle. The end of the tool holder body will force the
locking balls 32 radially outwardly to their outermost position.
Further pushing of the tool holder 10 onto the spindle will result
in the locking ring 42 abutting the locking balls 32. The tool
holder 10 can then be rotated until the locking balls 32 are in
register with the pockets 70 in the locking ring, whereupon the
tool holder may be pushed further into the spindle until the
rearwardly disposed face of the annular plate 44 abuts the end of
the spindle, and the locking balls 32 are received in the pockets
70. This is the intermediate position which is referred to below.
The sleeve 40 is then rotated in an anticlockwise direction by
about 45.degree. which causes rotation of the tool holder body 14
via the annular plate 44. Because the locking balls 32 are in their
radially outermost position, they cannot be received in the
relatively shallow portions 72 of the recesses 68, and the locking
ring remains stationary with respect to the spindle, and so
rotates, with respect to the sleeve 40 in a clockwise direction
against the bias of the spring 62. The rotation of the sleeve (40)
causes rotation of the tool holder body (14) via the annular plate
(44). As soon as the tool holder 10 has been rotated about the
spindle by about 45.degree., the depressions 38 in the tool holder
body 14 will become in register with the locking balls 32 and the
locking balls will move radially inwardly into their locking
position in which they are received in the depressions 38. This
radial movement of the locking balls 32 enables them to be received
by the relatively shallow portions 72 of the recesses 68 in the
locking ring 42, whereupon the locking ring will rotate in the
anticlockwise direction under the bias of the spring 62 into its
locking position with a clearly audible snap. The tool holder 10 is
then firmly fixed on the end of the spindle.
[0040] In this operation, it is not necessary for the operator to
align the tool holder with any parts of the spindle. The tool
holder is simply pushed into the spindle, rotated until the locking
balls 32 are received within the pockets 70 (observed a further
axial movement of the tool holder 10) and the ring 40 rotated
further until the locking ring 42 snaps into its locking
position.
[0041] In order to remove the tool holder 10 from the spindle 1,
the sleeve 40 is simply rotated by about 45.degree. in the
clockwise direction. This movement forces the locking ring 42 to
rotate with the sleeve 40, but tool holder body 14 and the annular
plate 44 remain stationary, due to the locking balls 32 engaging
the depressions 38. Thus, with respect to the sleeve 40 and locking
ring 42, the tool holder body and annular plate rotate in an
anticlockwise direction against the bias of the spring 62. When the
locking ring 42 has rotated so that the locking balls 32 are in
register with the pockets 70, the locking balls 32 will immediately
move radially outwardly into the pockets. The tool holder body 14
is now free to move and will rotate in the clockwise direction
under the bias of the spring 62 until the protuberances 52 once
again abut the internal shoulders 54 in the sleeve 40, and the
depressions 38 are out of register with the locking bodies 32 and
the recesses (38) in the tool holder body are out of register with
the locking balls (32). This rotation also occurs with a clearly
audible snap. The tool holder may then simply be pulled axially off
the spindle 1.
[0042] A modified form of tool holder is shown in FIGS. 3 and 4.
This form of tool holder is essentially the same as that shown in
FIGS. 1 and 2, but instead of a snap ring 43, the locking ring 42
is held within the interior of the sleeve 40 by means of a
retention ring 100 having a generally "L" shaped circumferential
cross-section. The retention ring 100 is provided with four flap
portions 102 which fit inside the interior of the sleeve 40, and
are each provided with a small protuberance 104, as shown in the
shape of a double-headed arrow, that will fit inside a
corresponding hole 106 in the wall of the sleeve to provide a
positive engagement of the retention ring 100 in the sleeve 40.
* * * * *