Cutlery – Cutting tools – Saw
Reexamination Certificate
2001-05-15
2003-09-02
Payer, Hwei-Siu (Department: 3724)
Cutlery
Cutting tools
Saw
C030S337000, C279S075000
Reexamination Certificate
active
06612039
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to blade mounting devices that permit a blade to be easily and reliably attached to a machine tool, such as a reciprocating saw or a jigsaw. Such blade mounting devices are also known as keyless or tool-less blade clamps or clamping systems for attaching a saw blade to a reciprocating saw.
2. Description of the Related Art
A known tool-less blade clamp for reciprocating saws is disclosed in the U.S. Pat. No. 5,575,071, which is reproduced herein as FIG.
13
. The known blade mounting device
30
includes an axially reciprocating rod
31
driven by a motor, a blade lock operation sleeve (clamp collar)
32
rotatably attached to the end of the rod
31
and a torsion spring
34
that biases the blade lock operation sleeve
32
toward a blade clamping position. The blade
35
is inserted into a slot
31
a
having a uniform width and cross-section. A bearing support hole (aperture)
31
b
also is formed at the end of the rod
31
and a ball or bearing
33
is disposed within the bearing support hole
31
b
. The inner surface of the blade lock operation sleeve
32
has a cam face with a gradually varying internal diameter. The bearing
33
is supported between the cam face and the bearing support hole
31
b
. A guide or stop pin
36
is disposed within a slot
32
a
that is radially disposed within the blade lock operation sleeve
32
. The blade lock operation sleeve
32
rotates about the rod
31
within the range in which the guide pin
36
can move within the slot
32
a.
In order to mount a blade, the blade lock operation sleeve
32
is manually rotated toward a blade release position against the biasing force of the spring
34
. As a result of the manual rotation, the bearing
33
moves to the large-diameter side of the cam face and thus moves away from the slot
31
a
. Therefore, the base of the blade
35
may be inserted into the slot
31
a
. When the base of the blade
35
is inserted into the slit
31
a
and the blade lock operation sleeve
32
is not restrained by the operator from returning to the blade clamping position, the blade lock operation sleeve
32
rotates toward the blade clamping position due to the biasing force of the spring
34
. As the sleeve
32
reaches the blade clamping position, the bearing
33
is pressed toward the small-diameter side of the cam face. Therefore, the bearing
33
is pushed into the support hole
31
b
and protrudes from the slot
31
a
. The bearing
33
thereby lodges within a blade lock hole
35
a
of the blade
35
and the blade
35
is secured to the rod
31
.
According to the known blade mounting device
30
, the sleeve
32
must be manually held in the blade release position when the blade
35
is being inserted or withdrawn from the sleeve
32
. Thus, the blade insertion and withdrawal operations require the operator to manually hold the sleeve
32
in the blade release position with one hand and insert or withdraw the blade
35
with the other hand. This requirement present a danger that the operator will be injured by the saw blade, because it can be difficult to change saw blades while firmly holding the sleeve
32
at the same time. The blade mounting devices of Japanese Patent No. 2000-117534 and WO 97/31745 also appear to share this problem.
U.S. Pat. No. 5,946,810 teaches a blade mounting device (chucking tube) that can be locked in the blade release position in order to overcome this problem. However, the chucking tube of the '810 patent must be axially displaced relative to the reciprocating rod along a threaded portion in order to tighten the blade within the blade mounting device. That is, the blade mounting device of the '810 patent can not utilize a ball or bearing to firmly secure the saw blade to the rod along a longitudinal face of the saw blade and the saw blade receiving slot. Instead, the blade mounting device of the '810 patent only supports or fixes the blade at the outermost tip of the blade and along a peripheral edge of a pair of lugs that extend perpendicularly from the longitudinal face of the saw blade. Because the saw blade is not supported along the longitudinal face of the saw blade, the saw blade can wobble or shake during a cutting operation. Further, the blade mounting device of the '810 patent can not be utilized with standardized saw blade designs and can only be utilized with a saw blade having the pair of lugs formed on the shank portion of the blade. Moreover, even though insertion of the saw blade will release the chucking tube from the blade release position, the operator must still manually rotate the chucking tube in order to clamp or fix the blade within the chucking tube. In fact, the operator must manually rotate the chucking tube while pressing the saw blade inwardly against the biasing force of a compression spring in order to ensure that the saw blade is securely fixed.
Consequently, there is a long-felt need for a blade mounting device that can conveniently and reliably attach a saw blade to a reciprocating rod.
SUMMARY OF THE INVENTION
It is, accordingly, one object of the present teachings to provide improved blade mounting devices. For example, improved blade mounting devices may have a relatively simple structure and preferably permit the blade to be easily mounted on or withdrawn from the machine tool, such as a reciprocating saw. The improved blade mounting device also may firmly support a longitudinal face of the saw blade in order to prevent the saw blade from wobbling or shaking during a cutting operation. Moreover, improved blade mounting devices preferably can be utilized with saw blades having standard universal designs.
In one representative embodiment of the present teachings, a blade mounting device may include a blade lock operating member, a blade lock control member and a blade lock. The blade lock operating member preferably moves between a blade clamping position and a blade release position. The blade lock operating member may be normally biased towards the blade clamping position. The blade lock control member preferably moves between a blade lock preventing position and a blade lock permitting position. The blade lock control member prevents the blade lock operating member from moving to the blade clamping position when the blade lock control member is located at the blade lock preventing position. Further, the blade lock control member permits the blade lock operating member to move to the blade clamping position when the blade lock control member is located at the blade lock permitting position. The blade lock control member is pushed and moved from the blade lock preventing position to the blade lock permitting position by the blade when the blade is inserted to the rod. The blade lock securely clamps or attaches the blade to the rod when the blade lock operating member moves to the blade clamping position.
In another aspect of the present teachings, the blade lock operating member can move to the blade clamping position when the blade lock control member is in the blade lock permitting position. Further, the blade moves the blade lock control member when the blade is inserted into the rod. Because the blade lock control member moves to the blade lock permitting position due to the insertion of the blade into the rod of the machine tool, the blade clamping operation can be easily performed without requiring a special operation of the blade lock operating member.
In another aspect of the present teachings, blade mounting devices may include an L-shaped slot. A pin may be received within the L-shaped slot. The pin may travel along one portion of the L-shaped slot to change the blade mounting device from a blade clamping position to a blade release position. The pin may then move along the other portion of the L-shaped slot in order to lock the blade mounting device in the blade release position. Therefore, the blade mounting device can be locked in the blade release position in order to permit the operator to change saw blades without being required to manuall
Kakiuchi Yasuhiro
Mori Shinsuke
Dennison, Schultz & Dougherty
Makita Corporation
Payer Hwei-Siu
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