Metal deforming – By or with work-constrainer and/or manipulated work-forcer – Comprising work-stopping abutment
Reexamination Certificate
2002-07-16
2004-04-20
Ostrager, Allen (Department: 3725)
Metal deforming
By or with work-constrainer and/or manipulated work-forcer
Comprising work-stopping abutment
C072S018200, C072S031100, C072S031110, C072S420000, C072S389300
Reexamination Certificate
active
06722181
ABSTRACT:
This application claims priority to Japanese Patent Application 2001-217181 filed on Jul. 17, 2001, the disclosure of which is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
The invention relates to a bending method for bending a work of a plate shape by moving a die, with the work being butted against a butting member. The invention also relates to a bending apparatus, such as a press brake, for conducting such bending.
A typical press brake is, as shown in
FIGS. 5 and 6
, composed of a press machine main unit
1
and a back gauge mechanism
2
arranged behind the press machine main unit
1
. In the press machine main unit
1
, a ram
5
holding an upper die
3
and a table
6
holding a lower die
4
are positioned so as to vertically oppose to each other. The ram
5
is moved upward and downward by a reciprocating mechanism driven by a hydraulic cylinder or a servomotor. A work W is bent to a predetermined angle when the reciprocating mechanism is driven to lower the upper die
3
for pushing the work W by a predetermined amount into a V-shaped groove of the lower die
4
.
The back gauge mechanism
2
has a pair of butting members
9
and
10
against which the rear end edge of the work W is butted. The members
9
and
10
are arranged side by side. Each of the butting members
9
and
10
are moveable forward and backward (indicated as an “A” direction in FIG.
6
), side to side (indicated as an “E” direction in FIG.
6
), and upward and downward (indicated as a “C” direction in FIG.
5
). In
FIG. 6
a slide guide
11
supports the butting members
9
and
10
such that the butting members are able to slide in the sideways directions E in a reciprocating manner. Both the end portions of the slide guide
11
are connected to drive mechanisms
12
and
13
, such as ball screw mechanisms, respectively. Prior to bending work, the right and left drive mechanisms
12
and
13
are driven to define the positions of the butting members
9
and
10
in the forward and backward directions, or the A direction. The work W is sent to be positioned between the upper die
3
and the lower die
4
of the press machine main unit
1
, and is butted against each of the butting members
9
and
10
at the rear end edge thereof. A predetermined bending dimension is obtained when the work W is bent while the work is being butted in this way.
FIGS. 7 and 8
show a state when the work W of a plate shape, i.e., having a plate shape, is bent. In
FIG. 7
, a distance B
1
between a rear end edge
15
and a bending position
16
of the work W is generally referred to as an “absolute dimension of bending.” Further, in
FIG. 8
, a distance L between the rear end edge
15
of the bent work W and an intersection point Po at which planes passing through the outer faces of the work W cross is referred to as an “outer bending dimension.” Also, a distance B
2
between the rear end edge
15
of the bent work W and an intersection point Pi at which planes passing through the inner faces of the work W cross is referred to as an “inner bending dimension.” The outer dimension L and the inner dimension B
2
with a bending angle of 90° are shown in FIG.
9
.
The outer dimension L is generally larger than the absolute dimension B
1
, and the difference between the two is referred to as an “elongation amount.” This “elongation amount” of an outer dimension is dependent on bending conditions including a bending angle and a thickness of the work W. A “bending dimension” generally means the outer dimension L. This is because drawings for sheet-metal working often carry the outer dimension L, and further, the outer dimension L is the most easily measurable dimension in the measurement of the work W with a measuring device such as a vernier caliper after completing bending. Accordingly, as used herein, the “bending dimension” means the outer dimension L.
Generally, prior to bending, the material and the thickness of the work W, conditions of bending such as dies, a target value of a bending dimension, and a target value of a bending angle are given. A bending dimension can be determined by calculating an elongation amount from the bending conditions and the target value of a bending angle, obtaining the absolute dimension B
1
by the subtraction of the elongation amount from the target value of a bending dimension, and then, as shown in
FIG. 10
, setting a distance S, measured between a blade tip
3
a
of the upper die
3
and the butting members
9
and
10
of the back gauge mechanism
2
, equal to the absolute dimension B
1
. Further, a bending angle can be determined, as shown in
FIG. 11
, by a push-in amount of the work W into a groove
4
a
of the lower die
4
. The push-in amount is in other words a movement distance d (hereinafter referred to as an “operation amount”) measured between a contact position Y
1
where the upper die
3
contacts with the work W and an endmost position Y
2
of the downward movement of the upper die
3
. This operation amount is computed in advance from the given bending conditions and the target value of a bending angle.
Whether or not a target bending dimension and a target bending angle are achievable when bending the work W of a plate shape with the press brake having the arrangement described above is confirmed by trial bending of the work W.
First, an elongation amount in bending is computed, and then the butting members
9
and
10
of the back gauge mechanism
2
are positioned based on the computed value and the target value of a bending dimension. Next, the operation amount d of the upper die
3
is computed, and the work W positioned by the back gauge mechanism
2
is bent when the upper die
3
is moved according to the computed value of the operation amount d.
After the trial bending described above, the work W is taken out, and a bending angle is measured with a device such as a protractor. When the measured value of the bending angle agrees with a target value, the bending dimension is also measured with a device such as a vernier caliper. If the measured value of the bending angle does not agree with the target value, the bending dimension is not measured. This is because an elongation amount is dependent on a bending angle, and therefore, as long as a measured value of a bending angle does not agree with a target value of the bending angle, there is no way to know the difference between a target value of a bending dimension and a measured value of the bending dimension through the measurement of a bending dimension.
When the measured value of a bending angle does not agree with the target value, an operation amount of the upper die
3
is corrected according to an amount of the error. After the correction, trial bending may be again conducted to confirm that a measured value of a bending angle agrees with the target value.
When a measured value of a bending angle agrees with the target value, a bending dimension is measured with a device such as a vernier caliper. Here, positions of the butting members
9
and
10
are corrected when the measured value does not agree with the target value. After the correction, trial bending may be again conducted to confirm that the measure value of a bending dimension agrees with the target value.
Generally, a target bending angle and a target bending dimension are not obtainable when bending is made only based on an elongation amount and an operation amount obtained by computation. Therefore, according to the method of adjustment described above, the press machine main unit
1
is first adjusted to obtain a target bending angle, and then the back gauge mechanism
2
is adjusted to obtain a target bending dimension. This requires at least one time of trial bending for adjustment to obtain a target bending angle, and also requires at least one time of trial bending for adjustment to obtain a target bending dimension. Thus, at least two times in total of trial bending must be conducted in this case.
SUMMARY OF THE INVENTION
The invention was made to solve such problems described above, and it is an ob
Goetz John S
Hunton & Williams LLP
Ostrager Allen
Toyokoki Co., Ltd.
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