Metal deforming – Tool and/or tool holder – Having unitary tool-face
Reexamination Certificate
2001-05-11
2003-05-06
Larson, Lowell A. (Department: 3725)
Metal deforming
Tool and/or tool holder
Having unitary tool-face
C072S481100, C072S481600
Reexamination Certificate
active
06557390
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to press brakes of the type used to shape sheet-like workpieces. More particularly, this invention relates to press brake tool holders that are used to releasably retain forming tools in a press brake.
BACKGROUND
Press brakes are commonly used to shape sheet-like workpieces, such as sheet metal and the like. A conventional press brake includes an upper table and a lower table, at least one of which is movable toward and away from the other. Typically, the upper table is movable vertically, while the lower table is fixed in a stationary position. It is common for a male forming tool and a female forming die to be carried respectively by the upper and lower tables of a press brake.
Typically, the forming tool has a downwardly-oriented workpiece-deforming surface (or tip). The configuration of this surface is dictated by the shape into which it is desired to bend workpieces. The forming die has a recess that is aligned with the workpiece-deforming surface of the tool. The configuration of the recess corresponds to that of the workpiece-deforming tool surface. Thus, when the tables are brought together, a workpiece between the two is pressed by the tool into the die to give the workpiece the desired bend.
Various tool holders have been devised to mount a forming tool to the upper table of a press brake. For example, U.S. Pat. No. 5,619,885, the teachings of which are incorporated herein by reference, discloses a tool holder with a tool clamp member that is pivotally attached to a stationary support plate. During use, the clamp member exerts a clamping force upon the shank of a forming tool. To keep the tool from falling when the clamping force is released, the clamp member is provided with a projection that is engageable with a complementary drop-prevention groove formed in the tool.
In order to accurately deform workpieces, it is necessary for the forming tool to be mounted securely to the tool holder. This is accomplished by forcibly clamping the tool holder to the forming tool (i.e., by applying a clamping force to the tool). Multiple steps are typically required to operatively mount a forming tool on a conventional tool holder. This is perhaps best understood with reference to
FIGS. 1-3
, which illustrate a particularly useful press brake tool holder. The illustrated tool holder is disclosed in U.S. Pat. No. 6,003,360, the teachings of which are incorporated herein by reference.
As illustrated in
FIG. 1
, the forming tool
28
is initially mounted loosely to the tool holder
10
. Specifically, the mounting tang
30
of the tool
28
is lifted upwardly between a support plate
14
and a clamp
42
of the tool holder
10
. As the tool
28
is moved into the unclamped position illustrated in
FIG. 1
, a safety slot
122
on the tool
28
is engaged by a lip
116
of the clamp
42
. Thus, the tool
28
is prevented from falling from the holder
10
by the engagement of the lip
116
and the safety slot
122
. Although the tool
28
is retained loosely by the holder
10
in this position, it is not operatively clamped therein. Specifically, the load-bearing surfaces
24
,
26
of the support plate
14
and forming tool
28
are not brought into secure engagement with one another by simply mounting the tool
28
in its unclamped position. Rather, additional steps are required to mount the tool
28
in its operative position.
The upper and lower tables of the press brake are subsequently moved together until the forming tool comes into contact with a forming die on the lower table. This is best understood with reference to
FIG. 2
, wherein the tip
38
of the loosely-mounted tool
28
has been moved into engagement with a forming die
168
on the lower table (not shown). By forcing the tip
38
of the tool
28
against the die
168
, the tool
28
is urged upwardly relative to the tool holder
10
until the load-bearing surface
26
of the tool
28
is moved into contact with the load-bearing surface
24
of the support plate
14
.
At this point, the tool
28
can be forcibly clamped (or locked) in its operative position. While maintaining the tool
28
in the position shown in
FIG. 2
, the lower portion
68
of the clamp
42
is pivoted toward the tool
28
. As this portion
68
of the clamp
42
closes upon the shank
30
of the tool
28
, the tool is clamped securely to the holder.
FIG. 3
illustrates the resulting operative position, wherein the load bearing surfaces
24
,
26
of the support plate
14
and the tool
28
are engaged and the mounting shank
30
of the tool
28
is forcibly clamped between the support plate
14
and the lower portion
68
of the clamp
42
. During operation, the tool holder
10
is locked in this clamped position. Thus, it can be seen that several steps are typically required to operatively mount a forming tool upon a tool holder.
It would be desirable to provide a tool holder that can be operatively clamped about a forming tool in such a way that the load-bearing surfaces of the tool and the holder are engaged as an adjunct of the clamping action of the tool holder (i.e., without having to press the tip of the loosely-clamped tool against a die on the lower table of the press brake).
SUMMARY OF THE INVENTION
A tool holder apparatus for a press brake is provided in a first embodiment of the present invention. The apparatus comprises a support plate having a first receiving surface. A pivotable clamp has an engagement portion that is moveable toward the first receiving surface of the support plate by pivoting the clamp. The engagement portion has therein formed a bore in which a lifting shaft is rotatably received. The engagement portion defines an opening communicating with the bore. The shaft has therein formed a notch that is adapted to be engaged through the opening by an exterior corner of a forming tool. The notch is configured such that when the engagement portion of the clamp is forced against such tool, a first surface of the exterior tool corner bears against a first surface portion of the notch and causes the shaft to rotate within the bore, thereby bringing a second surface portion of the notch to bear against a second surface of the exterior tool corner and delivering to the tool a mounting force having a component normal to the second surface of the exterior tool corner.
In another aspect of the invention, there is provided a tool holder assembly for a press brake. The assembly comprises a support plate having a first receiving surface and a load-bearing receiving surface. A forming tool has a first mounting surface on a first side thereof and an exterior corner (i.e., an exterior tool corner) on a second side thereof. The first mounting surface of the tool is engaged with the first receiving surface of the support plate. The tool has a load-bearing mounting surface forming an included right angle with the first mounting surface. The load-bearing mounting surface is adapted to engage the load-bearing surface of the support plate. A pivotable clamp has an engagement portion that is moveable toward the first receiving surface by pivoting the clamp. The engagement portion has therein formed a bore in which a lifting shaft is rotatably received. The engagement portion defines an opening communicating with the bore. The shaft has therein formed a notch that is adapted to be engaged through the opening by the exterior corner of the forming tool. The notch is configured such that when the engagement portion of the clamp is forced against the tool, a first surface of the exterior tool corner bears against a first surface portion of the notch and causes the shaft to rotate within the bore, thereby bringing a second surface portion of the notch to bear against a second surface of the exterior tool corner. Thus, delivering to the tool a mounting force having a component normal to the second surface of the exterior tool corner.
In still another aspect of the invention, there is provided an upper press brake assembly. The assembly comprises an upper press brake table including a tool holder
Harrington Heath E.
Johnson Paul T.
Runk David M.
Shuldes Glen
Timp Richard L.
Fredrikson & Byron , P.A.
Larson Lowell A.
Wilson Tool International Inc.
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