U.S. patent application number 10/975063 was filed with the patent office on 2005-06-09 for blade clamp for reciprocating saw.
Invention is credited to Wilson, Mike.
Application Number | 20050120568 10/975063 |
Document ID | / |
Family ID | 29725463 |
Filed Date | 2005-06-09 |
United States Patent
Application |
20050120568 |
Kind Code |
A1 |
Wilson, Mike |
June 9, 2005 |
Blade clamp for reciprocating saw
Abstract
A jigsaw drive shaft is connected to a blade by the blade clamp
of the present invention. The blade clamp comprises a clamp body
mounted securely to the drive shaft by a bracket. The clamp body
has a hollow portion formed to receive an upper portion the jigsaw
blade. The clamp body also includes a hollow tubular extension. A
cam body is pivotable about an axis through a cylindrical bore such
that cam surfaces move in and out of contact with an interior
surface of the clamp body to engage or release the blade. A spring
biases the cam body into engagement with the clamp body surface.
The user must press on a protrusion of the cam body to pivot the
cam surfaces way from the clamp surface and against the force of
the spring.
Inventors: |
Wilson, Mike; (Crook,
GB) |
Correspondence
Address: |
Sr. Group Patent Counsel
Balck & Decker Corporation
701 E. Joppa Rd
Mail Stop TW199
Towson
MD
21286
US
|
Family ID: |
29725463 |
Appl. No.: |
10/975063 |
Filed: |
October 26, 2004 |
Current U.S.
Class: |
30/392 |
Current CPC
Class: |
Y10T 83/9461 20150401;
Y10T 83/9481 20150401; B23D 51/10 20130101; Y10T 279/17769
20150115 |
Class at
Publication: |
030/392 |
International
Class: |
B27B 003/12 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 28, 2003 |
GB |
GB0325077.6 |
Claims
1. A clamp assembly for removably mounting a working member of a
reciprocating tool to a reciprocating output shaft, the assembly
comprising:--a body member adapted to be mounted to said output
shaft; at least one engaging member having at least one first
engaging portion adapted to be located at least partially in front
of a respective second engaging portion on said working member in
the direction of reciprocation of the working member, wherein said
engaging member is pivotable in use relative to said body member
between a first position, in which said first engaging portion
engages said second engaging portion to retain the working member
in position on the output shaft, and a second position in which the
working member is removable from the output shaft; and first
biasing means for urging said engaging member towards said first
position; wherein application of a force to said working member
tending to remove the working member from the body member when at
least one said engaging member is in a first position thereof
causes movement of at least one said second engaging portion to be
prevented by the corresponding said first engaging portion.
2. An assembly according to claim 1, comprising a plurality of said
first engaging portions, wherein at least one said first engaging
portion is capable of limited pivotal movement relative to at least
one other said first engaging portion.
3. An assembly according to claim 2, comprising a plurality of said
engaging members, wherein at least one said engaging member is
capable of limited pivotal movement relative to at least one other
said engaging member about a common axis.
4. An assembly according to claim 3, comprising at least one first
said engaging member having a respective protrusion, and at least
one corresponding second said engaging member having a respective
recess for receiving at least one respective said protrusion,
wherein at least one said recess permits limited pivotal movement
of the corresponding said protrusion therein such that the
corresponding said first engaging member is pivotable about said
common axis.
5. An assembly according to claim 1, wherein at least one said
engaging member further comprises at least one elongate protrusion
adapted to enable the user to pivot said engaging means towards
said second position.
6. An assembly according to claim 5, wherein at least one said
elongate protrusion is formed on a corresponding said first
engaging member.
7. An assembly according to claim 5, wherein said first biasing
means comprises at least one torsional spring adapted to engage at
least one said elongate protrusion and said body member.
8. An assembly according to clam 1, wherein at least one said first
engaging portion comprises at least one respective cam surface for
engaging the working member and wherein application of a force to
said working member so as to remove the working member from the
output shaft urges at least one said cam surface further into
engagement with said working member.
9. An assembly according to claim 1, wherein the or each said
engaging member is adapted to be displaced from the first position
thereof by movement of the working member towards the output shaft
to enable mounting of the working member to the assembly by such
movement thereof.
10. A reciprocating tool using a replaceable working member, said
tool comprising:--a body; a motor having a rotary shaft; drive
means for converting rotary movement of said rotary shaft to
reciprocating movement of an output shaft; and a clamp assembly for
removably mounting the working member to the output shaft, the
assembly comprising a body member adapted to be mounted to said
output shaft; at least one engaging member having at least one
first engaging portion adapted to be located at least partially in
front of a respective second engaging portion on said working
member in the direction of reciprocation of the working member,
wherein said engaging member is pivotable in use relative to said
body member between a first position, in which said first engaging
portion engages said second engaging portion to retain the working
member in position on the output shaft, and a second position in
which the working member is removable from the output shaft; and
first biasing means for urging said engaging member towards said
first position; wherein application of a force to said working
member tending to remove the working member from the body member
when at least one said engaging member is in a first position
thereof causes movement of at least one said second engaging
portion to be prevented by the corresponding said first engaging
portion.
11. A tool according to claim 10, wherein the tool comprises a
jigsaw.
12. A tool according to claim 10, wherein at least one said second
engaging portion comprises at least one respective slot.
13. A tool according to claim 10, wherein said working member is a
saw blade and at least one said second engaging portion is provided
in an edge of the blade.
14. A tool according to claim 10, further comprising a second
biasing means for urging said working member out of engagement with
said output shaft.
15. A jig saw comprising a: a housing; a motor having a rotary
output shaft a reciprocating drive shaft a transmission connected
between the rotary output shaft and the reciprocating drive shaft
and converting the rotation of the motor output shaft into
reciprocating movement of the drive shaft; a removable saw blade
including a cutting portion and a shank, the shank including an
engaging portion and defining a slot between the engaging portion
and the cutting portion; and a blade clamping assembly, the blade
clamping assembly including: a body member connected to the drive
shaft; a cam body pivotably connected to the body member and
including an engaging surface, the cam body pivotable between a
first position and a second position. a first spring for biasing
the cam body into the first position; and wherein when the cam body
is in the first position then the cam body engaging surface extends
into the saw blade shank slot to retain the saw blade in the blade
clamp assembly, and when in the second position then the cam body
engaging surface is retracted from the saw blade shank slot so that
the saw blade is removable from the blade clamp assembly.
16. A jig saw according to claim 15, wherein the cam body engaging
surface is a cam shaped surface.
17. A jig saw according to claim 15, wherein the saw blade shank
slot is a first slot and the saw blade shank defines a second slot,
and wherein the cam body is a first cam body and the engaging
surface is a first engaging surface, and the blade clamping
assembly further includes: a second cam body pivotably connected to
the body member and coaxial with the first cam body, the second cam
body including a second engaging surface, and pivotable between a
first position and a second position. a second spring for biasing
the second cam body into the first position; and wherein when the
first cam body and the second cam body are in the first position
then the first engaging surface extends into the saw blade shank's
firsts slot and the second engaging surfaces extends into the saw
blade shank's second slot to retain the saw blade in the blade
clamp assembly, and when in the second position then the first
engaging surface is retracted from the first slot and the second
engaging surface is retracted from the second slot so that the saw
blade is removable from the blade clamp assembly.
18. A jig saw according to claim 17 wherein the first cam body and
second cam body are loosely interconnected so as to permit limited
rotational movement between the first cam body and the second cam
body as they pivot from the second position to the first
position.
19. A jig saw according to claim 17 wherein the first cam body
includes a protruding lever for pivoting the first cam body and the
second cam body from the first position to the second position
against the biasing forces of the first spring and the second
spring, for the purpose of removing the saw blade from the blade
clamp assembly.
20. A jig saw according to claim 15 and further comprising a
biasing means for urging the saw blade out of the blade clamp
assembly.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a clamp assembly for a
working member of a reciprocating tool and relates particularly,
but not exclusively, to a clamp assembly for the blade of a
reciprocating jigsaw.
BACKGROUND OF THE INVENTION
[0002] Jigsaws are power tools which comprise a reciprocating saw
blade for cutting a work piece of wood or other material. Most
jigsaws comprise a plastic housing containing an electric motor.
The rotary output of the motor is geared to a drive conversion
mechanism which converts rotary motion of the motor output into
reciprocating motion of an output shaft to cause reciprocating
motion of a saw blade.
[0003] Jigsaws are usually designed to enable the blade to be
removed from the output shaft. This serves two purposes. Firstly,
due to the high frictional forces encountered when in use, jigsaw
blades are subject to wear and tear and have limited lifetimes, so
that there is a necessity to enable the blade to be easily
replaced. Secondly, several different types of blade may be
supplied with the jigsaw to enable it to be used to cut a variety
of different types of workpiece, or cut the workpiece in a variety
of ways.
[0004] European Patent Application EP0792713 describes a jigsaw
blade clamp which comprises a channel formed in a jigsaw output
shaft shaped to accommodate a jigsaw blade and a pin that is urged
into contact with the blade by a spring, such that the pin forces
the blade into the channel thereby holding it in place. This prior
art clamp suffers from the drawback that if sufficient force is
applied to the blade, it can still slip out of place and even be
pulled away from the jigsaw.
[0005] Preferred embodiments of the present invention seek to
overcome the above disadvantage of the prior art.
BRIEF SUMMARY OF THE INVENTION
[0006] According to an aspect of the present invention, there is
provided a clamp assembly for removably mounting a working member
of a reciprocating tool to a reciprocating output shaft, the
assembly comprising:--
[0007] a body member adapted to be mounted to said output
shaft;
[0008] at least one engaging member having at least one first
engaging portion adapted to be located at least partially in front
of a respective second engaging portion on said working member in
the direction of reciprocation of the working member, wherein said
engaging member is pivotable in use relative to said body member
between a first position, in which said first engaging portion
engages said second engaging portion to retain the working member
in position on the output shaft, and a second position in which the
working member is removable from the output shaft; and
[0009] first biasing means for urging said engaging member towards
said first position;
[0010] wherein application of a force to said working member
tending to remove the working member from the body member when at
least one said engaging member is in a first position thereof
causes movement of at least one said second engaging portion to be
prevented by the corresponding said first engaging portion.
[0011] By providing a clamp assembly in which at least one first
engaging portion of an engaging member is adapted to be located
partially front of a respective second engaging portion on the
working member (in the direction of reciprocation of the working
member), this provides the advantage that the working member can be
more effectively held in position on the tool than a clamp assembly
using friction alone.
[0012] The assembly may comprise a plurality of said first engaging
portions, wherein at least one said first engaging portion is
capable of limited pivotal movement relative to at least one other
said first engaging portion.
[0013] This provides the advantage of minimising the risk that only
one side of an engaging member correctly holds the working member
in position, for example as a result of manufacturing
tolerances.
[0014] In a preferred embodiment, the assembly comprises a
plurality of said engaging members, wherein at least one said
engaging member is capable of limited pivotal movement relative to
at least one other said engaging member about a common axis.
[0015] The assembly may comprise at least one first said engaging
member having a respective protrusion, and at least one
corresponding second said engaging member having a respective
recess for receiving at least one respective said protrusion,
wherein at least one said recess permits limited pivotal movement
of the corresponding said protrusion therein such that the
corresponding said first engaging member is pivotable about said
common axis.
[0016] This provides the advantage that manufacturing tolerances
can be accommodated by enabling a plurality of the engaging members
to be pivotable about a common axis relative to each other, while
enabling pivoting of a single engaging member by a user to cause
pivoting of more than one engaging member.
[0017] In a preferred embodiment, at least one said engaging member
further comprises at least one elongate protrusion adapted to
enable the user to pivot said engaging means towards said second
position.
[0018] This provides the advantage that it is made easier for the
user to release the blade from the clamp by minimising the force
which the user needs to apply to the engaging member because of
leverage obtained by the elongate protrusion.
[0019] At least one said elongate protrusion may be formed on a
corresponding said first engaging member.
[0020] Said first biasing means may comprise at least one torsional
spring adapted to engage at least one said elongate protrusion and
said body member.
[0021] In a preferred embodiment, at least one said first engaging
portion comprises at least one respective cam surface for engaging
the working member wherein application of a force to said working
member so as to remove the working member from the output shaft
urges at least one said cam surface further into engagement with
said working member.
[0022] This provides the advantage that if the working member is
pulled outwardly of the tool, the grip provided by the clamp on the
working member is tightened.
[0023] The or each said engaging member may be adapted to be
displaced from the first position thereof by movement of the
working member towards the output shaft to enable mounting of the
working member to the assembly by such movement thereof.
[0024] According to another aspect of the present invention, there
is provided a reciprocating tool comprising:--
[0025] a body;
[0026] a motor having a rotary shaft;
[0027] drive means for converting rotary movement of said rotary
shaft to reciprocating movement of an output shaft; and
[0028] a clamp assembly as defined above.
[0029] In a preferred embodiment, the tool comprises a jigsaw.
[0030] The tool may further comprise at least one working member
having at least one second engaging portion for engaging at least
one corresponding said first engaging portion.
[0031] At least one said second engaging portion may comprise at
least one respective slot.
[0032] In a preferred embodiment, said working member is a saw
blade and at least one said second engaging portion is provided in
an edge of the blade.
[0033] The tool may further comprise second biasing means for
urging said working member out of engagement with said output
shaft.
[0034] This provides the advantage of facilitating removal of the
working member from the tool, as well as providing an indication
whether the working member is correctly mounted to the tool.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Preferred embodiments of the present invention will now be
described, by way of example only and not in any limitative sense,
with reference to the accompanying drawings in which:--
[0036] FIG. 1 is a perspective side view of a jigsaw;
[0037] FIG. 2a is a front and side perspective view of a jigsaw
drive shaft and blade clamp of a first embodiment of the present
invention;
[0038] FIG. 2b is a rear and side perspective view of the jigsaw
blade clamp and drive shaft of FIG. 2a;
[0039] FIG. 2c is a front perspective view of the jigsaw drive
shaft and blade clamp of FIG. 2a;
[0040] FIG. 3 is a side view of a blade to be used with the blade
clamp of FIG. 2;
[0041] FIG. 4a is a sideways perspective view of a body of the
blade clamp of FIG. 2;
[0042] FIG. 4b is a front view of the blade clamp body of FIG.
4a;
[0043] FIG. 4c is a side view of the blade clamp body of FIG.
4a;
[0044] FIG. 4d is a rear view of the blade clamp body of FIG.
4a;
[0045] FIG. 5 is a perspective view of a cam body of the blade
clamp of FIG. 2;
[0046] FIG. 6 is a side cross sectional view of the blade of FIG. 3
mounted to the blade clamp body of FIG. 4;
[0047] FIG. 7 is a front view of the blade and blade clamp of FIG.
2;
[0048] FIG. 8 is a cross sectional view of the upper part of the
blade of FIG. 3 received in the blade clamp of FIG. 2;
[0049] FIG. 9a is a side perspective view of a first part of a cam
body of a second embodiment of the invention;
[0050] FIG. 9b is a side view of the cam body of FIG. 9a;
[0051] FIG. 9c is a bottom view of the cam body of FIG. 9a;
[0052] FIG. 9d is a front view of the cam body of FIG. 9a;
[0053] FIG. 10a is a side perspective view of a second part of the
cam body of the embodiment of FIG. 9;
[0054] FIG. 10b is a side view of the cam body of FIG. 10a;
[0055] FIG. 10c is a bottom view of the cam body of FIG. 10a;
[0056] FIG. 10d is a front view of the cam body of FIG. 10a;
[0057] FIG. 11 is a partially cut away side perspective view of the
first cam part of FIG. 9 and the second cam part of FIG. 10 mounted
in the clamp body of FIG. 4;
[0058] FIG. 12a is a side view of a first spring for use with the
embodiment of FIGS. 9 to 11;
[0059] FIG. 12b is a front view of the spring of FIG. 12a;
[0060] FIG. 13a is a side view of a second spring for use with the
embodiment of the FIGS. 9 to 11;
[0061] FIG. 13b is a front view of the spring of FIG. 13a; and
[0062] FIG. 14 is a side view of a cam body pin of the embodiment
of FIGS. 9 to 13.
DETAILED DESCRIPTION OF THE INVENTION
[0063] Referring to FIG. 1, a jigsaw shown generally by 1 has a
housing 2 of durable plastics material, with a motor (not shown)
disposed therein. The motor has a rotary output shaft (not shown)
geared to a drive mechanism which converts the rotary output of the
motor into vertical reciprocating motion of a drive shaft (not
shown). The housing 2 is mounted on a shoe 4 which rests on a
workpiece and provides a reaction force for the blade 3 during
upward movement thereof. The blade 3 is attached to the drive shaft
(not shown) by a blade clamp 5.
[0064] Referring now to FIG. 3, a blade to be used with the present
invention will now be described. The blade shown generally by 3 has
a cutting portion 8 of length defined by 6 and width defined by W.
As will be appreciated by persons skilled in the art, one edge of
the blade is provided with cutting teeth (not shown). At the upper
end of the cutting portion 8 the width of the blade is reduced at a
portion of the blade defined by 7, to form two indents 9. Above the
indents 9 is a portion of the upper part of the blade as shown by
10 which has width less than W.
[0065] Referring now to FIGS. 2a to 2c, the jigsaw drive shaft 11
is connected to the blade 3 by a jigsaw blade clamp 5 embodying the
present invention. Referring also to FIGS. 4a to 4d, the jigsaw
blade clamp comprises a blade clamp body 12 which is mounted
securely to the drive shaft 11 by means of a bracket 13. The blade
clamp body 12 has a hollow interior 14 formed to receive the upper
portion 7 of the jigsaw blade (FIG. 3). This is shown best in FIG.
6, in which the upper part of the blade 3 is received fully in the
hollow portion 14. The blade clamp body 12 also includes a hollow
tubular extension 15.
[0066] Referring to FIG. 5, a cam body 16 for cooperating with the
clamp body 12 is shown. The cam body 16 comprises two cam surfaces
17 and an elongate protrusion 18. An indentation 19 is formed on
the protrusion 18, the purpose of which will be described in
greater detail below. The cam body 16 also comprises a cylindrical
bore 20. The cam body 16 is formed such that it can be inserted
into the hollow portion 14 of the clamp body 12. This is shown best
in FIGS. 2a and 2c. When the cam body 16 is fully received in the
clamp body 12 the cylindrical bore 20 of the cam body 16 is aligned
with the hollow tubular extension 15 of the clamp body 12. A pin
(not shown) is inserted such that it passes through the hollow
tubular extension 15, and through the cylindrical bore 20, to
enable the cam body 16 to be pivoted relative to the clamp body 12.
A torsional spring 21 is mounted co axially on tubular extension
15. A first end 22 of the torsional spring 21 is securely received
in a slot 23 formed in the clamp body 12. A second end 24 of the
spring 21 rests in the indentation 19 formed in the protrusion 18
of the cam body 16.
[0067] The operation of the jigsaw blade clamp will now be
described.
[0068] Referring to FIG. 7, the cam body 16 is able to pivot about
an axis through the cylindrical bore 20 such that the cam surfaces
17 move in and out of contact with the rear surface of the hollow
portion 14 of the clamp body 12. By virtue of the resilient action
of spring 21, the cam body 16 is urged into the clamp body 12. In
order to pivot the cam surfaces 17 away from the clamp body 12, the
user must press on protrusion 18 in the direction of the blade such
that the cam body 16 is pivoted out of clamp body 12 against the
action of spring 21.
[0069] When a blade is mounted in the hollow portion of the clamp
body 12, as shown in FIG. 6, the cam surfaces 17 engage indents 9
of blade 3. The blade 3 is prevented from slipping out of the clamp
body 12 as the cam surfaces 17 are received in indents 9 and
therefore are in contact with the protrusions 10 of the blade 3. If
the blade 3 is pulled in a downward direction, the force exerted on
cam surfaces 17 by projections 10 causes the cam surfaces 17 to be
pivoted into further engagement with the blade 3, thereby
tightening the grip of the blade clamp 5 on the blade 3.
[0070] In order to effect the release of the blade 3 from the blade
clamp 5, the cam body 16 is pivoted out of clamp body 12 by
pressing on protrusion 18, such that the cam surfaces 17 move out
of engagement with indentations 9 of the blade 3. Referring to FIG.
8, which shows the top of blade 3 engaged in the clamp body 12, a
leaf spring 25 contacts the top edge of the blade 3, such that when
the clamp 5 is opened the compressed leaf spring 25 extends, thus
pushing the blade 3 out of engagement with clamp body 12. This not
only facilitates removal of the blade from the clamp 5, but also
ensures the blade 3 is correctly engaged with clamp 5 until the
protrusion 18 is pressed.
[0071] Referring now to FIGS. 9 to 14, a second embodiment of the
present invention is shown with parts common to the embodiment of
FIGS. 1 to 8 denoted by like reference numerals but increased by
100.
[0072] Referring to FIGS. 9a to 9d, the cam body of this embodiment
is formed from two separate parts. A first cam body part 130 is
formed from durable plastics material. The first cam body part 130
comprises a first cam surface 134 for engaging a blade indent 9 of
the blade 3 in the same way as the cam surfaces 17 engage the blade
of the embodiment of FIGS. 1 to 8. An elongate protrusion 118
extends from the first cam body part 130 and is provided to enable
a user to easily pivot the cam body part 130. The first cam body
part 130 has a first cylindrical bore 138 for receiving a pin (not
shown) to enable the cam body part 130 to be pivoted about an axis
through the bore 138. A ridge 142 is formed around the
circumference of cylindrical bore 138, the purpose of which will be
described below. A peg 146 is also formed integrally with the first
cam body part 130, the purpose of which will also be described
below.
[0073] Referring now to FIGS. 10a to 10d, the second cam body part
132 comprises a second cam surface 136 for engagement with an
indent 9 of blade 3. A second cylindrical bore 140 is formed with a
circular recess 144 adapted to receive ridge 142 of the first cam
body part 130, such that when the first and second cam body parts
130, 132 are mounted to each other, the first and second
cylindrical bores 138, 140 form a continuous single cylindrical
bore with a common axis. The second cam body part 132 is also
provided with an aperture 148 in which peg 146 is received when the
first and second cam body parts 130, 132 are attached to one
another.
[0074] The first and second cam body parts 130, 132 are adapted to
be mounted on a pin 150 (FIG. 14) such that the pin 150 passes
through first and second cylindrical bores 138, 140 and each cam
body part 130, 132 is independently pivotable to a limited extent
about the pin 150.
[0075] Referring to FIG. 11, the first and second cam body parts
130, 132 are shown mounted in a blade clamp body 112. The blade
clamp body 112 is identical to the blade clamp body 12 from the
first embodiment of the invention. Coil springs 152, 154 (FIGS. 12
and 13) are mounted on the cylindrical bore portions 138, 140 of
the cam body parts 130, 132 respectively such that the coiled
portions 156, 158 of the springs are coaxial with the cylindrical
bore of the assembly. Each coil spring has a first end 160, 162
which is secured to the respective cam body part 130, 132 and a
second end 164, 166 secured to the blade clamp body 112.
[0076] The operation of the jigsaw blade clamp of FIGS. 9 to 14
will now be described.
[0077] Referring to FIG. 11, in order to release a blade from the
blade clamp, the user depresses elongate protrusion 118 to pivot
first cam body part 130 about pin 150. This moves the first cam
surface 134 out of engagement with the indentation 9 of blade 3. At
the same time, peg 146 moves in the aperture 148 of the second cam
body part 132 until the first cam body part 130 has moved
sufficiently about the axis such that the peg 146 abuts the edge of
the aperture 148. Further depression of elongate protrusion 118
then also causes second cam body part 132 to pivot about pin 150,
thus moving the second cam surface 136 out of engagement with the
other indentation 9 of blade 3. When the elongate protrusion 118
has been fully compressed, the blade is released.
[0078] As the peg 146 has a limited amount of travel in aperture
148, each cam body part 130, 132 is independently pivotable to a
limited extent about the pin 150. However the user only has to move
the first cam body part 130 in order to effect eventual movement of
the second cam body part 132. Independent movement of the first and
second cam body parts 130, 132 will therefore absorb any
manufacturing tolerances in the cam surfaces themselves or the
indentations of the blades.
[0079] It will be appreciated by persons skilled in the art that
the above embodiments have been described by way of example only
and not in any limitative sense, and various alterations and
modifications are possible without departure from the scope of the
invention as defined by the appended claims.
* * * * *