Negative angle-forming die

Details Negative angle-forming die Negative angle-forming die

1999-12-23

2001-05-15

Crane, Daniel C. (Department: 3725)

Metal deforming

By use of non-deforming work-gripping clamp and relatively...

With interrelated clamp closer and tool mover

C072S387000, C072S452900

Reexamination Certificate

active

06230536

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a negative angle-forming die for forming metallic thin plates. In this context, a negative angle-forming die is used for forming in which a portion of a work is intruded into a lower die further than a descending locus in a straight direction of an upper die.
2. Description of the Background Art
Negative angle forming wherein a work of metallic thin plate is intruded into a lower die than a descending locus of an upper die in a straight manner is usually performed by using a slide cam.
A conventional method for performing intrusion forming of a work of metallic thin plate (a workpiece) included the steps of placing the work onto a lower die, descending an upper die downward in a vertical direction, driving a passive cam of the lower die by an active cam of the upper die for processing the work from a lateral direction, and after the upper die was raised upon completion of processing, the active cam was retracted by a spring.
In this case, a forming portion of the passive cam that forms the work by being slid from outside of the work in a lateral direction is uniformly formed to assume a shape that is identical to that of a forming portion of the work. However, since the work needs to be taken out from the lower die upon completion of processing, the forming portion of the lower die onto which the work is mounted is either arranged in that an intruding portion of the lower die is provided to be separable for retraction or in that a rear portion of the intruding portion is cut off and the work is moved forward for enabling the work to be taken out. While it does not become problematic in case of a minor degree of intrusion, in case such a degree is large or the work is a long and slender frame-like part having a grooved section such as a front pillar outer of metallic thin plate used in a vehicle, it may happen in case the intruding portion of the lower die is divided or cut off that, owing to the narrow groove width of the work, no clear shape can be formed by the forming portion of the passive cam and moreover, that insufficient strength of the lower die makes it impossible to perform intrusion forming at all.
Further, there are also cases in which torsions or warps are formed in products so that correction of products needs to be performed, while correction of products is practically impossible in case of parts constituting an outer panel portion of a vehicle such as a side panel, fender, roof, bonnet, trunk lid, door panel or front pillar outer all of which assume three-dimensional curved surfaces and curved lines. In case of assembling metallic thin plates for a vehicle, products which assume torsions or warps can be hardly combined to other parts, and it could not be provided for a structure of metallic thin plates for a vehicle of high quality and it could not be maintained for a specified degree of product accuracy required for the product of metallic thin plate.
For solving the above problems, it has been devised for an arrangement as follows for converting descending, straight movements of the upper die into rotational movements for rotating a columnar body, forming a forming portion that is intruded into the lower die further than a straightly descending locus of the upper die, and after completion of forming, retracting the columnar body in a rotating manner to an extent that a formed work can be taken out form the lower die.
That is, as shown in
FIGS. 8
to
11
, the negative angle-forming die is comprised of a lower die
102
for mounting a work W of metallic thin plate onto a supporting portion
101
thereof and an upper die
103
that is descended in a straight direction towards the lower die
102
for forming the work W by hitting against the work W, wherein there are further provided a columnar body
106
arranged in a freely rotating manner on the lower die
102
and having a groove
104
that is open to an outer peripheral surface and that is carved into an axial direction as well as an intruding forming portion
105
formed at an edge portion of the groove
104
closer to the supporting portion
101
that is intruded further than a locus of the upper die
103
, a slide cam
108
formed with an intruding forming portion
107
being arranged on the upper die
103
in a freely sliding manner as to oppose the columnar body
106
, and an automatic returning tool
109
arranged at the lower die
102
for retracting the columnar body
106
in a rotating manner to an extent with which the work W can be taken out from the lower die
102
upon completion of forming, wherein the work W that is mounted on the supporting portion
101
of the lower die
102
is formed through the intruding forming portion
105
of the columnar body
106
and the intruding forming portion
107
of the slide cam
108
while the columnar body
106
is rotated and the slide cam
108
performs sliding movements, and after completion of forming, the columnar body
106
is retracted in a rotating manner by the automatic returning tool
109
such that the formed work W can be taken out from the lower die
102
.
Operations of such a negative angle-forming die will now be explained.
As shown in
FIG. 8
, the upper die
103
is first positioned at a top dead center at which time the work W is mounted on to the supporting portion
101
of the lower die
102
. At this time, the columnar body
106
is retracted in a rotating manner by the automatic returning tool
109
.
Next, the upper die
103
starts to descend, and as shown in
FIG. 9
, the slide cam
108
is first made to abut against a rotating plate
111
of the slide cam
108
without interfering the intruding forming portion
105
of the columnar body
106
so as to rotate the columnar body
106
in a rightward direction in
FIG. 9
to put the columnar body
106
into a forming posture, and thereafter, a pad
110
pressurizes the work W.
When the upper die
103
keeps on descending, the slide cam
108
that is energized in a direction outside of the die moves leftward in a lateral direction of the drawing by the action of the cam against energizing force of a coil spring
112
to assume a condition as shown in
FIG. 10
, whereby intrusion forming of the work W is performed through the intruding forming portion
105
of the rotated columnar body
106
and the intruding forming portion
107
of the slide cam
108
.
After intrusion forming is completed, the upper die
103
starts rising. The slide cam
108
, being energized in a direction outside of the die by the coil spring
112
, is moved rightward in
FIG. 11
so that it can be raised without interfering the work W.
On the other hand, accompanying the rising movements of the slide cam
108
which had been constraining the columnar body
106
, the columnar body
106
rotates leftward in FIG.
11
through the automatic returning tool
109
. In this manner, when taking the work W out from the lower die
102
after intrusion forming, the work W can be taken out without interfering the intruding forming portion
105
of the columnar body
106
.
In the above-described negative angle-forming process, a lower surface of the slide cam
108
that is energized by the coil spring
112
abuts against the rotating plate
111
that is energized by a coil spring
113
of the automatic returning tool
109
to rotate the columnar body
106
in a rightward direction such that the columnar body
106
assumes a forming posture whereupon the pad
110
pressurizes the work W. However, drawbacks are presented in that negative angle-forming processes of favorable quality cannot be performed in case the work W in the forming posture is rotated to some extent in the leftward direction in the drawing since the energizing force applied to the work W that is mounted on the pad
110
is too large, or in case the energizing force of the coil spring
112
of the slide cam
108
and that of the coil spring
113
of the automatic returning tool
109
are not balanced, whereby the columnar body
106
is slightly rotated such that it cannot m

Affiliated with

Also associated with

Rating

Negative angle-forming die does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Negative angle-forming die, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Negative angle-forming die will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2546361