U.S. patent application number 10/760688 was filed with the patent office on 2004-08-26 for shoe clamping mechanism for power tool incorporating such.
Invention is credited to Wadge, Brian.
Application Number | 20040163263 10/760688 |
Document ID | / |
Family ID | 9952592 |
Filed Date | 2004-08-26 |
United States Patent
Application |
20040163263 |
Kind Code |
A1 |
Wadge, Brian |
August 26, 2004 |
Shoe clamping mechanism for power tool incorporating such
Abstract
A mechanism is disclosed for clamping a jigsaw (1) shoe in a
desired position relative to the body of a power tool. A plurality
of gear (22, 26) teeth are used to allow greater torque and access
as compared to prior art clamping mechanisms.
Inventors: |
Wadge, Brian; (Coxhoe,
GB) |
Correspondence
Address: |
Bruce S. Shapiro
Black & Decker Corporation
Mail Stop TW199
701 E. Joppa Rd
Towson
MD
21286
US
|
Family ID: |
9952592 |
Appl. No.: |
10/760688 |
Filed: |
January 20, 2004 |
Current U.S.
Class: |
30/376 ;
30/392 |
Current CPC
Class: |
Y10T 83/9457 20150401;
Y10T 83/6875 20150401; B23D 49/167 20130101 |
Class at
Publication: |
030/376 ;
030/392 |
International
Class: |
B27B 011/10 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 7, 2003 |
GB |
GB 0302787.7 |
Claims
1. A shoe clamping mechanism for a power tool having a housing, a
working member extending from the housing, and a shoe for engaging
a workpiece and adapted to be clamped in a plurality of
orientations relative to the working member, the mechanism
comprising: clamping means having a clamping portion and a mounting
portion, wherein the clamping means is adapted to be mounted to the
tool such that rotation of said mounting portion relative to the
housing about a first axis causes movement of said clamping portion
between a first position in which said shoe is pivotable relative
to the working member and a second position in which said shoe is
clamped in position relative to said working member; actuating
means adapted to be pivoted about a second axis, substantially
parallel to said first axis and displaced therefrom; and torque
adjusting means connected to said actuating means and said clamping
means wherein application of a first torque to pivot said actuating
means about said second axis causes application of a second torque,
higher than said first torque, to said clamping means to rotate
said mounting portion about said first axis.
2. A mechanism according to claim 1, wherein the torque adjusting
means comprises a gear mechanism.
3. A mechanism according to claim 2, wherein the gear mechanism
comprises a first gear having a plurality of first gear teeth and
mounted to said actuating means and a second gear having a
plurality of second gear teeth and connected to said mounting
portion, wherein the number of said second gear teeth is larger
than the number of said first gear teeth.
4. A mechanism according to claim 1, wherein the clamping portion
comprises a clamping plate restrained in use from rotating about
said first axis.
5. A mechanism according to claim 4, further comprising a track for
receiving said clamping plate and fixed in position relative to
said housing.
7. A mechanism according to any claim 1, wherein the mounting
portion includes a thumb wheel.
7. A mechanism according to claim 1, wherein the mounting portion
includes a screw thread.
8. A tool comprising a housing, a working member extending from the
housing, a shoe engagable with a workpiece and clampable in a
plurality of orientations relative to the working member, and a
shoe clamping assembly comprising: a clamp; a mount, rotation of
said mount relative to the housing about a first axis causing
movement of said clamp between a first position in which said shoe
is pivotable relative to the working member and a second position
in which said shoe is clamped in position relative to said working
member; a thumb wheel pivotable about a second axis, substantially
parallel to said first axis and displaced therefrom; a gear
mechanism connected between said thumb wheel and said clamp,
wherein application of a first torque to pivot said thumb wheel
about said second axis causes application of a second torque to
said mount to rotate said mount about said first axis.
9. A tool according to claim 8, wherein the shoe comprises a first
arcuate portion for cooperating with a second arcuate portion on
the housing.
10. A tool according to claim 9, wherein the shoe plate comprises
an aperture adapted to receive said clamp.
11. The tool recited in claim 8, said gear mechanism comprising a
first gear connected to said thumb wheel and a second gear
connected to said mount.
12. A tool according to claim 11, wherein said tool is a
reciprocating saw.
Description
[0001] The present invention relates to a shoe clamping mechanism
for a power tool, and to a power tool incorporating such a
mechanism. The invention relates particularly, but not exclusively,
to a shoe clamping mechanism for a jigsaw.
BACKGROUND OF THE INVENTION
[0002] Jigsaws generally include a housing containing a motor for
driving a saw blade in a reciprocating manner. A shoe, having a
generally flat lower surface for location against a workpiece to be
cut by the saw, is mounted to the housing of the saw, and forms a
reaction surface such that when the saw blade moves away from the
workpiece, the shoe forms a reaction surface to enable cutting
action, whereas when the blade moves towards the workpiece, debris
produced by the cutting action is displaced from the vicinity of
the blade.
[0003] In order to enable bevel cutting of a workpiece, it is
desirable to provide a shoe which is pivotable relative to the
housing about a longitudinal axis, and a clamping mechanism for
clamping the shoe in one or more desired orientations relative to
the saw blade. In this way, when the shoe rests on a workpiece,
bevel cutting at an angle corresponding to the angle of inclination
between the shoe and the saw housing is also possible.
[0004] DE 19546162 discloses a clamping mechanism for a shoe of a
jigsaw in which a shoe can be clamped in a plurality of
orientations relative to a housing of the jigsaw by means of
rotation of a double threaded screw about its longitudinal axis by
means of a lever. Rotation of the lever in one direction causes the
shoe to be clamped in position between a clamping plate and the
housing, whereas rotation of the lever in the opposite direction
increases the separation between the clamping plate and the housing
to allow the shoe to be pivoted relative to the saw blade.
[0005] However, this prior art arrangement suffers from the
drawback that the provision of a screw having oppositely wound
threads increases the cost of production of the apparatus, and the
provision of a lever pivoting about the longitudinal axis of the
double threaded screw still limits the extent to which the lever
can be rotated in the space available between the shoe and the saw
housing.
[0006] EP 0603552 discloses a shoe clamping mechanism for a saw in
which rotation of a screw thread about a first axis to clamp a shoe
in position relative to a saw housing is achieved by rotation of a
rotatable hand grip about a second axis perpendicular to the first
axis. Cooperating conical gears parallel to each axis ensure that
rotation of the hand grip about the second axis causes rotation of
the screw thread about the first axis. This arrangement suffers
from the drawback, however, that conical gears are expensive
components to manufacture and must be located relatively accurately
relative to each other, since the focuses of the two conical gears
must generally coincide with each other to ensure correct
operation. As a result, this significantly increases the cost of
production of a saw incorporating the clamping mechanism.
[0007] EP 0970771 discloses a jigsaw base clamping system in which
a shoe is fixed in a predetermined orientation relative to a saw
housing by means of a clamping mechanism incorporating moveable
wedge shaped ramps. This arrangement suffers from the drawback that
the large number of cooperating moving parts significantly
increases the cost of production of a tool incorporating the
mechanism.
[0008] Preferred embodiments of the present invention seek to
overcome the above disadvantages of the prior art.
BRIEF SUMMARY OF THE INVENTION
[0009] According to an aspect of the present invention, there is
provided a shoe clamping mechanism for a power tool having a
housing, a working member extending from the housing, and a shoe
for engaging a workpiece and adapted to be clamped in a plurality
of orientations relative to the working member, the mechanism
comprising:
[0010] clamping means having a clamping portion and a mounting
portion, wherein the clamping means is adapted to be mounted to the
tool such that rotation of said mounting portion relative to the
housing about a first axis causes movement of said clamping portion
between a first position in which said shoe is pivotable relative
to the working member and a second position in which said shoe is
clamped in position relative to said working member;
[0011] actuating means adapted to be pivoted about a second axis,
substantially parallel to said first axis and displaced therefrom;
and
[0012] torque adjusting means connected to said actuating means and
said clamping means wherein application of a first torque to pivot
said actuating means about said second axis causes application of a
second torque, higher than said first torque, to said clamping
means to rotate said mounting portion about said first axis.
[0013] By providing actuating means adapted to be pivoted about a
second axis substantially parallel to, but displaced from, said
first axis, this provides the advantage of making the actuating
means more accessible than in the prior art, while also enabling
the torque adjusting means to be constructed in a simple manner.
For example, the torque adjusting means could be in the form of
gears causing rotation of a first gear about a first axis as a
result of rotation of a second gear about a second axis,
complicated and expensive gear arrangements not being necessary if
the first and second axes are not generally parallel to each
other.
[0014] The torque adjusting means may comprise a gear
mechanism.
[0015] The gear mechanism may comprise a first gear having a
plurality of first gear teeth and mounted to said actuating means
and a second gear having a plurality of second gear teeth and
connected to said mounting portion, wherein the number of said
second gear teeth is larger than the number of said first gear
teeth.
[0016] This provides the advantage of enabling a higher torque to
be applied to the clamping means by means of a mechanism of simple
construction.
[0017] The clamping portion may comprise a clamping plate
restrained in use from rotating about said first axis.
[0018] The mechanism may further comprise a track for receiving
said clamping plate and fixed in position relative to said
housing.
[0019] The actuating means may comprise a thumb wheel.
[0020] The mounting portion may include a screw thread.
[0021] According to another aspect of the present invention, there
is provided a shoe assembly for a power tool having a housing, and
a working member extending from the housing, the assembly
comprising:
[0022] a shoe plate for engaging a workpiece and adapted to be
clamped in a plurality of orientations relative to the working
member; and
[0023] a shoe clamping mechanism as defined above.
[0024] The shoe plate may comprise a first arcuate portion for
cooperating with a second arcuate portion on the housing.
[0025] The shoe plate may further comprise an aperture adapted to
receive said clamping means.
[0026] According to a further aspect of the present invention,
there is provided a tool comprising:
[0027] a housing;
[0028] a working member extending from the housing; and
[0029] a shoe assembly as defined above.
[0030] The housing may further comprise a second arcuate portion
for engaging said first arcuate portion.
[0031] The tool may be a reciprocating saw.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] A preferred embodiment of the invention will now be
described, by way of example only and not in any limitative sense,
with reference to the accompanying drawings, in which:
[0033] FIG. 1 is a side view of a reciprocating saw embodying the
present invention;
[0034] FIG. 2 is a perspective view from below from the saw of FIG.
1;
[0035] FIG. 3 is a partially cut away, side perspective view of a
shoe assembly and housing of the saw of FIG. 1;
[0036] FIG. 4 is a perspective view of a shoe assembly of FIG. 3
when removed from the saw;
[0037] FIG. 5 is a further perspective view from below,
corresponding to FIG. 3, of the shoe assembly and housing of FIG.
3; and
[0038] FIG. 6 is a sectional view along the line X-X in FIG. 5.
DETAILED DESCRIPTION OF THE INVENTION
[0039] Referring to FIG. 1, a reciprocating saw such as a jigsaw
(1) has a housing (2) of durable plastics material in which a
handle (4) is formed. A trigger switch (not shown) for actuating
the saw is provided in the handle (4) and operates in a manner
which will be familiar to persons skilled in the art. The housing
(2) accommodates a motor (not shown), and a rotary output shaft of
the motor co-operates with a scotch yoke mechanism, as will be
familiar to persons skilled in the art and will therefore not be
described in further detail herein, to cause vertical reciprocating
motion of a jigsaw blade (6) in response to rotation of the rotary
output shaft of the motor.
[0040] A shoe or sole plate (8) is mounted to the housing (2) by
means of a clamping mechanism to be described in grater detail
below, and has a generally flat base (9) for resting on a workpiece
(not shown) in such a manner that as the jigsaw blade (6) moves
upwards as shown in FIG. 1, the sole plate (8) provides a reaction
surface to enable cutting action by the blade (6), and debris
produced by the cutting action is displaced away from the blade
during the downward stroke. The sole plate (8) is pivotable about a
longitudinal axis A-A (FIGS. 2 and 3) to adjust the orientation of
the base (9) relative to the blade (6) to enable bevel cutting of a
workpiece.
[0041] Referring now to FIGS. 2-6, the sole plate (8), which is
stamped from a single sheet of metal such as steel, has a concave,
longitudinally extending central portion (10) of generally
part-circular cross section in a direction transverse to axis A-A,
for mating with a corresponding convex portion (12) (FIG. 6) of the
jigsaw body (2) to enable pivoting of the sole plate (8) relative
to the body (2). In order to clamp the sole plate (8) in position
relative to the body (2), a grab plate (14) is in threaded
engagement with a screw thread (16) extending from the body (2) and
the grab plate (14) is prevented from rotating relative to the sole
plate (8), such that rotation of the screw thread (16) relative to
the sole plate (8) causes longitudinal movement of the grab plate
(14) along the screw thread (16). In other words, rotation of the
screw thread (16) in one sense causes the grab plate (14) to clamp
the concave central portion (10) in position between the grab plate
(14) and the convex portion (12) of the body (2) to prevent
pivoting of the sole plate (8) relative to the saw blade (6).
Similarly, rotation of the screw thread (16) in the opposite sense
causes the grab plate (14) and convex portion (12) to move further
apart to enable to sole plate (8) to pivot relative to the blade
(6). The grab plate (14) is prevented from rotating relative to the
sole plate (8) by means of a guide track (18) (FIG. 5), the track
(18) being fixed relative to the saw body (2). The sole plate (8)
is provided with a cut out portion (20) extending in a direction
perpendicular to the axis A-A for accommodating the screw thread
(16) at different orientations of the central portion (10) relative
to the housing (2).
[0042] In order to actuate the screw thread (16) to move the grab
plate (14) between a position in which the central portion (10) is
clamped in position between the grab plate (14) and convex portion
(12), and a position in which the sole plate (8) can pivot about
axis A-A relative to the body (2), a gear wheel (26) is mounted
coaxially with screw thread (16) and co-operates with a further
gear wheel (24) which is coaxially mounted to a thumb wheel (22).
In this way, the rotational axis of thumb wheel (22) is displaced
from the rotational axis of screw thread (16), thus making thumb
wheel (22) more accessible to the user in the limited space
available between the sole plate (8) and body (2). In addition, the
first gear (26) has a larger number of teeth than the second gear
(24), as a result of which application of a first torque to thumb
wheel (22) results in application of a second, higher torque to
screw thread (16). In this way, a higher torque can be applied to
screw thread 16 than if the user had applied a torque directly by
hand to the second gear (26), for example by means of a thumb wheel
(not shown) located coaxially with screw thread (16). As a result
of the improved accessibility of thumb wheel (22) in the limited
space available between the sole plate (8) and body (2), the thumb
wheel (22) can be rotated through approximately 270.degree. by a
user, without the user having to reposition his fingers.
[0043] It will be appreciated by persons skilled in the art that
the above embodiment has been described by way of example only, and
not in any limitative sense, and that various alterations and
modifications are possible without departure from the scope of the
invention as defined by the appended claims.
* * * * *