Note: Descriptions are shown in the official language in which they were submitted.
CA 02580891 2007-03-28
WORK BENCH INCLUDING A VISE
This is a divisional application of Canadian Patent Application 2,261,714
filed
August 6, 1997.
Field of the Invention
The invention relates to portable work benches or tables which include an
integral clamping table or vise. More particularly, the present invention
relates to a work
table with a clamping table or vise where the vise may be operated with one
hand.
Background of the Invention
Carpenters, woodworkers and handymen which work with wood as well as other
materials, often need a work bench or table which may be utilized to hold
workpieces.
Ordinarily, these work benches include a vise which clamps portions of the
table top
together to secure the workpiece on the table. One such device is that of the
assignee of
the present invention which is sold under the WORKMATE trademark. These tables
are
versatile, provide for secure clamping, are compact and are convertible to
dual height
positions.
The work bench ordinarily includes two vise screws with handles on each one.
The vise screws, via the handles, are operated by the user with the user using
both
hands. While a user may utilize one hand, the user must rotate both handles in
order to
clamp a workpiece between the clamping table members. Accordingly, it is
desirable to
utilize one hand to crank both of the vise screws so that clamping of the
workpiece may
be accomplished by the user using only one hand. By enabling cranking of the
vise to
clamp the workpiece with one hand, the user is capable of holding the
workpiece in
place with his other hand. Also, it is desirable that the vise clamp irregular
objects while
turning the vise screws with one hand.
Summary of the Invention
The invention is typically incorporated in a work bench including a frame; a
table surface on the frame, with the table surface including at least two
members; one of
which is movably coupled with the frame to enable clamping of a workpiece
between
the two table surface members. A drive mechanism moves the table members with
respect to one another. The drive mechanism includes two screws coupled with
one of
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the members. The two screws are spaced from one another to move the table
member
upon rotation of the screws. A sprocket is coupled with each screw. A
transmission belt
or chain is coupled with the sprocket to drive the screws together. At least
one handle is
coupled with one of the screws to rotate the screws. At least one clutch is
coupled with
at least one screw to limit clamping pressures on the workpiece. The clutch
enables
rotation of one screw with respect to the other screw so that irregular
workpieces may be
clamped between the table members and clamping of the workpiece may be
accomplished by rotation of the handle by one hand of the operator.
In accordance with the invention of the present divisional, there is provided
a
guard for a work bench having a drive transmission belt or chain comprising: a
first
wall, at least one second wall extending substantially perpendicular to said
first wall,
and a first guide extending from said first wall, said first guide extending
from said first
wall transverse to the direction of travel of the transmission belt or chain
and said first
guide directly contacting the belt or chain for applying tension on the belt
or chain, said
guard secured between two brackets on the work bench and prohibiting access to
the
drive transmission belt or chain. Preferably, a second guide extends from the
first wall.
Preferably, two parallel spaced second walls extend from the first wall. An
alignment
member extends from the first wall. Preferably, the alignment member is
stamped into
the first wall and two alignment members sandwich each guide member. Also, a
second
wall preferably includes a biasing member to provide positive belt or chain
tension. The
first or second walls may include cut-outs to secure the helical spring
biasing member to
the guard.
Additional features of the invention will be apparent from the detailed
description of the preferred embodiment, and the appended claims and
accompanying
drawings, or may be learned by practice of the invention.
Brief Description of the Drawings
The accompanying drawings, which are incorporated in and constitute a part of
the specification, illustrate one embodiment of the present invention and
together, with
the description, serve to explain the principles of the invention. In the
drawings, the
same reference numerals indicate the same parts.
Figure 1 is a perspective view of a work bench top in accordance with the
present invention.
Figure 2 is a side elevation view of the work bench with the top of Figure 1.
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Figure 3 is an exploded perspective view of Figure 1.
Figure 4 is a cross-section view of Figure 1 along line 4-4 thereof.
Figure 5 is a perspective partially in cross-section view of a portion of the
transmission drive of the present invention.
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Figure 6 is an enlarged perspective view of a portion of the drive.
Figure 7 is a perspective view of the handle without the knob in accordance
with
the present invention.
Figure 8 is a cross-section view of Figure 7 along line 8-8 thereof.
Figure 9 is a cross-section view of Figure 7 along line 9-9 thereof.
Figure 10 is an enlarged cross-section view of Figure 1 along line 10-10
thereof.
Detailed Description of the Preferred Embodiment
The preferred embodiment of the present invention is a work bench which is
identified with the reference numeral 10. The work bench includes a frame
structure 12
which includes a base 14, four foldable legs 16, two upright H supports 18
which extend
from the base 16, and brackets 20 at the other end of the supports 18. The
work bench
22 is generally formed from two members 24 and 26 which are coupled with the
brackets 20.
The brackets 20 are hollow and include elongated slots 21 which enable
movement of the front table 24 with respect to the brackets 20. Also, the
brackets
include apertures 23 to enable the second table portion 26 to be stationarily
locked onto
the brackets 20. An additional slot 25 is formed in the side of the brackets
20 to enable
the belt 56 to pass into the brackets 20 and be coupled with the sprockets 50.
Two screws 30 are positioned within the brackets 20. The screws include a
threaded portion 32 which includes a threaded pivot nut 34 which in turn, via
a block
36, is coupled with the front moving member 24 of the work bench 22. Also, the
screws
includes a smooth shank portion 38 which includes a portion which extends out
beyond the bracket 20 as seen in Figure 1. The smooth shank portion 38
includes a stop
25 40 as well as apertures 44 and 46.
Sprockets 50 are slidably positioned onto the smooth shank portion 38 of the
screws 30. The sprocket 50, as shown, has projecting members 52 which extend
into
apertures 54 of the belt 56. However, if a chain is used, the projections may
be
substituted for recesses or the like. The sprocket 50 includes a hub 58 which
includes
30 slots or detents 60. The slots 60 are adapted to couple with a detent pin
62 which passes
through aperture 44 of the screw 30.
A helical spring 64 is positioned on the smooth shank portion 38 abutting the
stop 40 and the sprocket 50. The spring 64 along with the detent pin 62,
sprocket 50 and
sprocket slots 60 act as a clutch which limits the pressure which can be
applied onto the
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workpiece. The slot or detent 60 in the sprocket enables transmission of light
torques
necessary to overcome friction to move the first member 24 providing one hand
operation. At high clamping torques, the pin 62 disengages from the sprocket
detent or
slot 60 and compresses the clutch spring 64. When unclamping the workpiece,
the
clutch automatically engages the pin 62 via the sprocket detent 60 to once
again allow
one handed operation. The clutch 70 could be incorporated on both screws or a
single
clutch may be provided. In the case of a single clutch, the other sprocket
will be
securely pinned to the vise screw. Preferably, each of the screws 30 includes
a clutch 70
as described above.
A guard 80 is positioned over the transmission belt or chain 56. The guard 80
includes a first wall 82 and at least one second wall 84, preferably two,
which are
perpendicular to the first wall 82 forming an overall U-shape and define a
channel 85.
The guard 80 includes two guides 86 stamped in and cut out of the first wall
82. The
guides 86 extend substantially perpendicular to the first wall 80 into the
channel 85. The
guides 86 are substantially parallel with the second wall 82 and apply tension
on the
leading 55 side of the belt 56. The guides 86 help to tension the belt or
chain as it moves
during rotation of the screws 30. Also, the guides 86 extend from the wall 82
transverse
to the direction of travel of the belt 56. The guard 80 spans the length of
the belt 56 and
is secured with the brackets 22 which, in turn, provides additional stability
for the frame
12.
Two embossed alignment members 90, 92 sandwich the guide 86. The alignment
members 90, 92 are stamped into the first wall 82 of the guard 80. The
alignment
members 90, 92 help to maintain the belt 56 or chain onto the sprockets 50
during the
clamping modes.
A biasing member 96 is secured to the second wall 82 to automatically adjust
for
changes in belt length and to take up slack in the belt 56. The biasing member
96 is a
helical spring which is secured on cut-outs 98, 99 in the guard 80. The spring
96 always
provides for positive belt 56 or chain tension. The spring 96 is positioned
under the belt
56 and tensions both the leading 55 and trailing 57 sides of the belt 56.
Each screw includes a handle 100 and 110. The handle 100 includes a hub 102, a
handle arm 104 and a knob 106. The handle 110 includes a hub 112, a straight
portion
114, a curved portion 116 and a knob 118. The hub 112 has a desired height
which is
larger than the straight portion 114, but less than the curved portion 116.
The curved
portion 116 has an overall truncated U-shape. Also, a connecting member 120
extends
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between the hub 112, straight portion 114, and curved portion 116. The handle
110
provides a visual indication to the user that the work bench clamping system
may be
rotated with one hand. Also, the hub 112 includes an aperture 122 which
enables a pin
124 to pass there-through to secure the handle on the screw 30 through the
aperture 46.
Likewise, the handle 100 includes an aperture and a pin to secure it on the
screw 30.
The work bench vise of the present invention is ordinarily operated as
follows.
One of the handles 100, 110 is rotated which, in turn, rotates either one of
the screws 30.
The rotation of the screw 30 rotates the sprocket 50 and via belt 56 rotates
the other
screw 30 via its sprocket 50. Thus, both of the screws 30 rotate at the same
time,
ordinarily, synchronously. As the user is utilizing one hand to rotate both
screws 50, the
user can use his other hand to hold the workpiece in between the two table
members 24,
26. As the table members 24, 26 contact the workpiece, and especially if the
workpiece
has an irregular shape, the front table member 24 will contact the workpiece
and the
sprocket 50 will compress against the spring 64 and move away from the pin 62,
thus
engaging the clutch 70. If an irregular shaped workpiece is between the table
portions,
then one of the screws 30 will not rotate due to the clutching effect while
the other will
continue to rotate to clamp on the irregular shape of the workpiece. Once the
workpiece
is initially clamped and not over tightened, the individual screws can be
shored up to
give a firm grip onto the workpiece.
While the above detailed description describes the preferred embodiment of the
present invention, the invention is susceptible to modification, variation,
and alteration
without deviating from the scope and fair meaning of the subjoined claims.
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