U.S. patent number 3,840,987 [Application Number 05/419,794] was granted by the patent office on 1974-10-15 for protective device for a power tool.
This patent grant is currently assigned to Thomas & Betts Corporation. Invention is credited to Louis A. Netta.
United States Patent |
3,840,987 |
Netta |
October 15, 1974 |
PROTECTIVE DEVICE FOR A POWER TOOL
Abstract
A selectively operable safety shield comprising a preferably
U-shaped member coupled to the frame of a power tool is biased
towards a first position straddling the normally exposed work zone
of the tool to restrict inadvertent contact with the moving members
thereof to prevent injury to an operator utilizing such tool. The
shield may be manipulated away from its closed position to
selectively expose the work zone by cooperative engagement with the
workpiece. Further movement of the shield may be accomplished by
attaching it to a preferably pivoting support coupled to the frame
of the tool to permit the tool to be engaged mid-span of a length
of the workpiece.
Inventors: |
Netta; Louis A. (North
Brunswick, NJ) |
Assignee: |
Thomas & Betts Corporation
(Elizabeth, NJ)
|
Family
ID: |
23663788 |
Appl.
No.: |
05/419,794 |
Filed: |
November 28, 1973 |
Current U.S.
Class: |
30/90.1; 30/91.2;
30/92; 30/182; 30/241 |
Current CPC
Class: |
F16P
3/04 (20130101); B21F 11/00 (20130101); H01R
43/042 (20130101) |
Current International
Class: |
F16P
3/00 (20060101); H01R 43/042 (20060101); F16P
3/04 (20060101); B21F 11/00 (20060101); H01R
43/04 (20060101); B21f 011/00 (); B26b 015/00 ();
B26b 029/00 () |
Field of
Search: |
;30/241,182,228,90.1,91.2,92 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Smith; Al Lawrence
Assistant Examiner: Zatarga; J. T.
Attorney, Agent or Firm: Teschner; David Woldman; Jesse
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. A protective device for a power tool having a normally exposed
work zone, comprising: frame means; shield means pivotably coupled
to said frame means and selectively movable between a first
position restricting access to said work zone, and a second
position permitting access to said work zone; means for coupling
said shield means to said frame-means so that said shield means is
selectively displaceable between said first position and said
second position; means cooperative with said shield means and said
frame means for biasing said shield means in said first position;
and means for selectively manipulating said shield means from said
first position to said second position, said manipulating means
being adapted to cooperatively engage a workpiece intended to be
inserted in said work zone to provide access to said work zone,
said shield means comprising a U-shaped member pivotably coupled to
said frame means, said U-shaped member having a lanced portion
adjacent the bight of said U-shaped member, said biasing means
comprising a torsion spring engaging said lanced portion and said
coupling means to bias said shield means towards said first
position.
2. A protective device as defined in claim 1 wherein said
manipulating means comprises a selectively formed flanged portion
extending outwardly from said shield means generally adjacent one
edge thereof.
3. A protective device as defined in claim 1 wherein said
manipulating means comprises a flanged portion extending outwardly
from each of the legs of said U-shaped member generally adjacent
one edge thereof.
4. A protective device as defined in claim 1 wherein said frame
means further comprises means for selectively limiting the extent
of travel of said shield means.
5. A protective device as defined in claim 4 wherein said travel
limiting means comprises pin means, and said shield means comprises
a slotted portion slidably engaging said pin means.
6. A protective device as defined in claim 1 further comprising
means for moving said shield means to a third position providing
further access to said work zone.
7. A protective device as defined in claim 6 wherein said frame
means comprises support means pivotable towards and away from said
work zone, said shield means being coupled to said support means so
that upon selective manipulation of said support means, said shield
means is moved from said first position to said third position.
8. A protective device as defined in claim 7 wherein said torsion
spring is cooperative with said shield means and said support
means.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is directed to the field of protective devices for
tools having normally exposed work zones.
2. Description of the Prior Art
Prior art tools which may be both manually and power operated and
which may include cutting and crimping devices in which the die
portions thereof are urged towards one another under relatively
high pressure generally comprise a suitably formed aperture
defining the work zone and are designed to unobstructively receive
the workpiece preparatory to the performance of the specified
operation thereon. The resulting exposed work zone generally
presents an extremely hazardous condition for an operator who may
inadvertently insert one or more fingers between the die members of
the tool while the power stroke is initiated. In view of the
increasing emphasis upon safety in the field of power tools and
equipment, it has become necessary to insure that such tools are
suitably protected so as to avoid injury to the operator under
substantially all conditions of operation. This increased concern
for safety has engendered an immediate need for a form of
protective device or guard means which is simple, convenient,
relatively tool-proof and easy to operate to ensure the safe
operation of the tool and protect the operator from injury in the
use thereof. Pivoting latch arrangements which permit the tool to
be placed over the mid-span of a conductor, or the like, wherein
the latch must be advanced to the fully closed position before
further operation can take place are disclosed in U.S. Pat. No.
2,722,859 issued Nov. 8, 1955 to H. C. Stoltz, and U.S. Pat. No.
2,772,715 issued Dec. 4, 1956 to K. L. Neijstrom et al. Neither of
these devices, however, will prevent the inadvertent insertion of
the operator's finger into the exposed work area or zone prior to
or during the power stroke. Existing protective guards or shields
which have been devised principally for use in conjunction with
stationary machinery comprise, in most cases, a stationary shield
at least partially surrounding the work area, requiring the
operator to engage in rather inconvenient, cumbersome, and
time-consuming manipulations to advance the work into the work
area. The operator is thus tempted to defeat the safety feature of
such guard or shield to increase his productive capacity, leading,
in many cases, to a condition more hazardous than that which the
guard or shield was designed to prevent.
SUMMARY OF THE INVENTION
The invention overcomes the problems and limitations noted above
with respect to prior art devices by providing a protective device
for power tools and the like, which is safer, more versatile,
simpler, more convenient, and more economical than such prior art
devices. The protective device comprises, in one embodiment, a
preferably U-shaped shield movably coupled to a die support
attached to the frame of a power tool and biased towards a first or
closed position straddling the normally exposed work zone of the
power tool to restrict inadvertent access thereto. The shield is
provided with manipulating means which may take the form of a
flanged shoulder arranged to abut the workpiece so that the shield
is displaced and the workpiece inserted into the work zone in
essentially one continuous operation. The shield is appropriately
biased to remain in contact with the workpiece during operation of
the tool so as to preclude the entry of any further material or a
part of the operator's body into the work zone during the power
stroke. In one embodiment, of a tool with which the shield may be
employed, the stationary die member of a two part shearing die may
be unlatched from its normal position and selectively pivoted away
from the work zone while one edge of the die engages a portion of
the shield so that the shield is also manipulated away from the
work zone as the tool is opened, for example, for mid-span
engagement about a conductor or the like. In a further embodiment,
the support member to which the shield is coupled is pivotingly
attached to the tool frame to permit the shield to be displaced to
a further or third position with respect to the work zone. The
operator may thus bring the tool to the workpiece and, in a single
operation, employ the workpiece to reposition the shield permitting
entry of the workpiece into the work zone in a safe, convenient,
and simple procedure. It is therefore an object of this invention
to provide a protective device for power tools and the like.
It is another object of this invention to provide means for
restricting inadvertent access to the normally exposed work zone of
a power tool and the like.
It is a further object of this invention to provide shield means
for a power tool or the like which may be manipulated by the
workpiece to provide access to the work zone.
It is still a further object of this invention to provide a movable
shield straddling the normally exposed work zone of a power tool or
the like and arranged to follow the contour of the workpiece to
minimally expose the work zone during the power stroke.
It is yet another object of this invention to provide a protective
device for a power tool or the like which may be manipulated from a
closed to an open position by engagement with the workpiece.
Other objects and features will be pointed out in the following
description and claims and illustrated in the accompanying drawings
which disclose by way of example the principle of the invention and
the best mode contemplated for carrying it out.
BRIEF DESCRIPTION OF THE DRAWINGS
In the Drawings
FIG. 1 is a fragmentary front elevational view, partly cut away and
partly in section, of a protective device for a power tool
constructed in accordance with the concepts of the invention.
FIG. 2 is a top plan view of the protective device illustrated in
FIG. 1.
FIG. 3 is a rear elevational view, partly cut away, of the
protective device illustrated in FIG. 1.
FIG. 4 is a fragmentary front elevational view, showing the device
of FIG. 1 in a partially open state, with a conductor, in section,
shown engaged therein.
FIG. 5 is a fragmentary front elevational view, of the device of
FIG. 1 selectively pivoted to an open position to show the manner
of mid-span engagement with a conductor, shown in section
therein.
FIG. 6 is a fragmentary front elevational view, partly cut away and
partly in section, of the device of FIG. 1 attached to a modified
form of the power tool illustrated in FIG. 1.
FIG. 7 is a fragmentary front elevational view, of the device of
FIG. 1 attached to a further modified form of the power tool
illustrated in FIG. 1, and showing a conductor, in section,
adjacent the work zone thereof.
FIG. 8 is a fragmentary front elevational view of another
embodiment of a protective device constructed in accordance with
the concepts of the invention.
FIG. 9 is a fragmentary rear elevational view, partly cut away and
partly in section, of the assembly illustrated in FIG. 1.
FIG. 10 is a fragmentary front elevational view, of the device of
FIG. 8 in a partially open state about an insulated conductor,
shown in section, disposed within the work zone of a power
tool.
Similar elements are given similar reference characters in each of
the respective drawings.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Turning now to FIGS. 1, 2, 3, 4 and 5 there is shown a power tool
20 having a protective device 22 constructed in accordance with the
concepts of the invention. The protective device 22 comprises an
essentially U-shaped shield 24 pivotingly coupled by means of a pin
26 to a first support means 28 affixed to the power tool frame 30.
A torsion spring 32 engages a lanced portion 34 located at the
bight of the U of the shield 24 and is brought around the coupling
pin 26 and thereafter into engagement with the first support means
28 as at 36. The torsion spring 32 biases the shield 24 in a
counterclockwise direction, as viewed in FIG. 1, to provide a
shutter-like restriction about a work zone 38 defined by the edges
of a first die member 40 and a second die member 42, which die
members, for the purpose of illustration only and not as a
limitation of the type of tool with which the shield 24 may be
employed, comprise a pair of blades suitable, for example, for
shearing electrical cable or the like. Each of the die members 40
and 42, respectively, thus comprise a relatively sharp, knife-like
inner edge 44 and 46, respectively. The lower die member 40 is
attached to a piston 48 fitted within a cylinder 50 to which may be
applied a hydraulic fluid such as, for example, oil or air through
a coupling 52 to drive the piston 48 and its associated die member
40 towards the stationary die member 42. The shield 24, in its
first or closed position, thus serves to shroud the aperture formed
by the work zone 38 to prevent inadvertent or accidental insertion
of the operators finger between the die members 40, 42. To
facilitate the manipulation of the shield 24 to a second or open
position, there is provided a pair of flanged portions 54, 56
adjacent the lower edge of the shield 24, and extending generally
perpendicularly outwardly from each of the leg portions of the
shield 24, as shown in greater detail in FIG. 3. For convenience,
each of the flanged portions 54, 56, is provided with an upturned
portion 58, 60 respectively, adjacent the free edge thereof to
facilitate engagement therewith by the workpiece which may include,
for example, a conductor such as 62, (see FIG. 4) the end of which
may be employed to raise the shield 24 sufficiently to provide
access to the work zone 38 and permit the conductor 62 to the
inserted therewithin. This procedure may be accomplished by placing
the end of the conductor 62 beneath either one of the flanged
portions 54, 56, and raising the conductor sufficiently to cause
the shield 24 to rotate about its coupling pin 26 to expose the
work zone 38 so that the conductor 62 may be advanced into the work
zone 38 between the die members 40, 42. The shield 24, being biased
towards the closed position by the torsion spring 32, will tend to
maintain intimate contact with the outer surface of the conductor
62 so as to at least partially shroud the remaining exposed portion
of the work zone 38 during the subsequent shearing operation. As
the conductor is removed from the work zone 38 upon completion of
the power stroke, the shield 24, being suitably biased, to cause to
rotate back to its first or closed position as illustrated in FIG.
1, thereby re-establishing a guard about the work zone 38
preparatory to the next operation. To control the extent of travel
of the shield 24 in its rotational movement, there is provided
therein a slotted portion 64 suitably dimensioned to receive a pin
66 attached to the support member 28. Thus, the right side of the
slotted portion 64, as viewed in FIG. 1, is arranged to abut the
pin 66 to restrict the counterclockwise movement of the shield 24
in its first or closed position whereas the left side of the
slotted portion 64 is arranged to provide a stop for the shield 24
in the open or second position. Although the shield 24 may be
conveniently manipulated by means of either one of the flanged
portions 54, 56, it may also be rotatably displaced from its first
or closed position by cooperative engagement with the upper die
member 42, as illustrated in greater detail in FIG. 5. As
illustrated therein, a second support member 68 pivotingly coupled
to the frame means 30 of the power tool 20 by means of a pin 70
comprises a retaining pin 72 adjacent its upper or free end. The
pin 72 is arranged to engage the hook like end 74 of the upper die
member 42 to releasably lock the die member 42 to the power tool
frame 30. To install the power tool 20 midspan of a conductor such
as 62 to effect the shearing thereof, the upper die member 42 is
released from its locked position by subjecting it to a slight
downward pressure to release its hook portion 74 from engagement
with the retaining pin 72. The upper die member 42 may then be
rotated about the pin 66 in a clockwise direction, as viewed in
FIG. 5, to the position shown therein. A rear edge 76 of the upper
die member 42 is thus caused to abut the shield 24 as at 78 causing
the shield 24 to follow the rotational movement of the upper die
member 42 so that the shield 24 is also rotated clockwise, as
viewed in FIG. 5, away from the work zone 38. The power tool 20 is
now opened sufficiently to permit its placement over the conductor
62 at any selected point along the length thereof. After the
conductor 62 is seated within the work zone 38 the upper die member
42 may then be rotated counterclockwise so that its hook portion 74
re-engages pin 72 to lock the upper die member 42 in its closed
position. The shield 24, being released from engagement with the
upper die member 42, will tend to pivot back towards its first or
closed position under the influence of the biasing spring 32 and
will abut the outer surface of the conductor 62 substantially as
shown in FIG. 4. As shown in greater detail in FIG. 9, the biasing
spring 32 is arranged to straddle the first support member 28 and
abut the outer surface thereof while slidably engaged about the pin
26 and supported at its other end about the lanced portion 34 of
shield 24. The diameter of the spring 32 may, of course, be
preselected to provide the desired biasing force for the shield 24
to insure that the shield 24 is properly maintained in its first or
closed position irrespective of the position of the power tool 20
during operation. Although a torsion spring is illustrated as
providing the biasing means for the shield 24, other suitable
arrangements may be provided, however, without departing from the
spirit of the invention and within the concepts herein disclosed,
such arrangement including, for example, compression or extension
springs (not shown) coupled between the shield 24 and the support
28, or suitably formed flat springs (not shown) bearing against the
shield 24 to maintain it in its first or closed position. The
flanged portion 54 of the shield 24, although shown as an
essentially planar element, may be arcuately formed as at 80 in
FIGS. 8 and 10 to more closely conform to the outer contour of, for
example a circular cross section cable or the like, or
alternatively, may have a polygonal configuration (not shown) where
necessary or desirable and within the concepts herein disclosed.
Further, the free end of the shield 24 may be extended as at 82
(FIGS. 8 and 10) to more fully encompass the workpiece and provide
a further restriction of the work zone 38 during the operative
cycle.
Referring now to FIG. 6 there is shown a power tool 84 similar in
construction to the power tool 20 except that the method of
coupling the first and second support members to the frame means of
the power tool is essentially reversed. As illustrated therein, the
power tool 84 comprises a first support member 86 which is
pivotingly coupled to the power tool 84 by a pin 88 and further
comprises a handle portion 90 for manipulating the support member
86 about the pin 88. A second support member 92 is affixed to the
frame of the power tool 84 by means of pins 94, 96, so that the
support member 86 may be selectively pivoted about the pin 88 while
the support member 92 is maintained in a stationary position. This
arrangement may be modified, however, as shown in FIG. 7 whereby
the support member 92 is also movably coupled to the power tool by
a pin 98 so that both support members may be selectively pivoted
away from the work zone. Thus, in the arrangement illustrated in
FIG. 7, as the support member 86 is pivoted about the pin 88 in a
clockwise direction, as viewed in FIG. 7, the shield 24 and the die
member 42 which are both coupled to the support member 86 are
caused to follow the movement thereof and be displaced from the
work zone simultaneously. Accordingly, the upper die member 42 and
the shield 24 may thus be independently or simultaneously pivoted
away from the work zone, as alternative arrangements, for either
mid-span or end engagement with the workpiece. Upon the return of
the support member 86 to its initial position, the leading edge of
the shield 24 is caused to contact the outer surface of the
workpiece 62 so that the shield 24 is pivoted backwardly against
the force of the biasing spring 32 to assume a position
substantially as shown in FIG. 4 during the subsequent operation of
the tool. It will of course also be clear that the shield 24 may be
provided with a further slotted portion (not shown) extending from
the aperture therein through which the pin 26 is inserted generally
parallel to the slotted portion 64 so that the shield 24 may be
displaced both laterally and rotationally from its first or closed
position to a predetermined second position substantially along the
two axis to provide an additional degree of movement which may be
found advantageous in certain applications.
Although there has been described in detail above the employment of
a shield, such as 24 in conjunction with a power tool designed
primarily for shearing, it will be clear to those skilled in the
art that such arrangement may be readily employed with equal
effectiveness in conjunction with existing compression and crimping
tools having a normally exposed work zone so that the previously
described hazardous condition resulting therefrom may be simply and
conveniently avoided. By reversing the location of the flanged
portions 54, 56 and suitably altering the location of the pins 26
and 66, and the slotted portion 64 of shield 24, the shield 24 may
be manipulated from its closed position to an open position in a
direction opposite to that described above, that is, as viewed in
FIG. 1, in a counterclockwise direction to provide an alternate
mode of operation. Additionally, the shield 24 may be provided with
flanged portions such as 54, 56 on both its upper and lower edges
to permit both clockwise and counterclockwise manipulation of the
shield, if necessary or desirable, and within the concepts herein
disclosed.
* * * * *