Metal deforming – With cleaning – descaling – or lubrication of work or product – Lubricating
Reexamination Certificate
1999-07-12
2001-04-17
Crane, Daniel C. (Department: 3725)
Metal deforming
With cleaning, descaling, or lubrication of work or product
Lubricating
C072S075000, C072S125000, C072S297000, C072S306000, C072S379200
Reexamination Certificate
active
06216508
ABSTRACT:
TECHNICAL FIELD
This invention relates to an improvement to an apparatus for progressively forming a sheet into any three-dimensional shape having a relatively large bottom area.
BACKGROUND OF THE INVENTION
For the plastic working of airplane and automobile parts, marine products such as boats, building materials, kitchen fitments, and bathroom fitments such as bath tubs, press-working using metal dies has been generally used. However, with methods using metal dies and presses, the plant is large and a large installation space is required, and plant costs and die-making costs are extremely high. Also, the forming of complex shapes is difficult and requires high-level process technology and finishing skill. Furthermore, because press operation produces noise and vibration it has an adverse affect on the environment, and safety measures have also been problematic.
One known alternative is the spinning method, but because this method involves molding a sheet by pressing it onto a rotating mold it has had the fatal shortcoming that it is only possible to form moldings whose cross-section is a circular cylindrical or conical shape.
In this connection, in Japanese Unexamined Patent Publication No. 7-132329, one of the present inventors has proposed a progressive sheet-forming method and apparatus. In this prior art, a barlike pressing member having a spherical end part is brought into contact with the underside of a sheet; a moving pressing member having a spherical pressing part is brought into contact with the other side (the upper side) of the sheet; and, with the periphery of the sheet held with a fixed holding force by a screw-type holding tool, the moving pressing member is moved around the barlike pressing member in correspondence with the cross-sectional shape of a product to be formed while the holding tool is moved in the thickness direction of the sheet by a spring-type cushion.
However, with this prior art, although the forming of simple diverging shapes such as conical shapes and pyramid shapes is possible, the forming of shapes wherein a bottom and a side wall part (trunk part) join at a sharp corner is not possible, and in particular, when the dimensions of a product are large, because the framelike holding tool supporting the sheet tends to incline and drop, there have been problems of forming becoming impossible or the accuracy of the formed shape deteriorating. Consequently the forming of products, typified by bath tubs and sinks, which have a large bottom area, of which furthermore the bottom profile shape may be irregular, and which have a high side wall part continuing from a bottom part, or which have a step at an intermediate level in a side wall, has been impossible.
Also, because this prior art is simple stretch-forming, carried out with the periphery of the sheet clamped, when the forming of a side wall which is vertical or at a near-vertical angle &agr; is carried out, a blank of a length l
0
in the horizontal state extends to a length l
1
, and along with this the sheet thickness decreases from t
0
to t
1
(t
1
=t
0
sin&agr;), so that for example a sheet thickness of 2 mm decreases to 0.17 mm, and thus the percentage sheet thickness decrease is high. Consequently there has been the problem that, depending on the material of the sheet and the sheet thickness, cracks may form in the side wall and local deformation may occur so that forming is almost impossible, and even if forming is possible there is a marked fall in strength.
There has also been the problem that when a hard sheet such as a stainless steel sheet is formed by this prior art method it is difficult to control spring-back, and formability and shape accuracy have consequently tended to be poor. And it has been a further problem that in cases where the product has not a simple flat flange but a bent-back flange it is not possible to carry out forming of this flange part.
DISCLOSURE OF THE INVENTION
It is therefore a first object of the invention to provide a dieless forming apparatus of a relatively simple construction with which it is possible to form to a high accuracy from a metal or nonmetal sheet a large three-dimensional product having a bottom with a complex profile and a large area and having a side wall part which is vertical or at a near-vertical angle.
It is a second object of the invention to provide a dieless forming apparatus with which the whole of a sheet is moved correctly in a balanced manner and therefore it is possible to form to a high shape accuracy a large product having a complex shape and a high side wall.
It is a third object of the invention to provide a dieless forming apparatus with which it is possible to carry out forming with good formability and precision by freely managing changes in sheet thickness and it is possible for example to form a product having a vertical or near-vertical side wall with good accuracy by suppressing reductions in sheet thickness or conversely to form a product whose angles to the horizontal are small with good accuracy by suppressing creasing deformation of the sheet material.
And it is further object of the invention to provide a dieless forming apparatus with which it is possible easily to form a product having a flange with a bent-back portion.
A dieless forming apparatus provided by the invention to achieve the above-mentioned first object is an apparatus for progressively forming a sheet into a three-dimensional shape, and comprises a tool set having a base plate, a fixed pressing assembly, a sheet holding mechanism and a sheet restraining mechanism; a pressing mechanism cooperating with the tool set; and a plurality of numerically controlled drive devices for moving the tool set and the pressing mechanism with respect to each other in X-axis, Y-axis and Z-axis directions.
The fixed pressing assembly has a stand erected on the base plate and a ceiling plate form having a plane shape matching the bottom profile of a product to be formed and interchangeably attached to the top of the stand, and the sheet holding mechanism has a plurality of support pillars mounted on the base plate, a support plate having a window hole surrounding the ceiling plate form and movable in the Z-axis direction on the support pillars, and at Least a pair of raising/lowering actuators fixed to the base plate and having output end parts connected to the support plate.
The sheet restraining mechanism has a framelike restraining plate for clamping the periphery of the sheet in the sheet thickness direction between itself and the support plate and restraining actuators for applying a controlled restraining force to the periphery of the sheet by way of the restraining plate.
The pressing mechanism has at a distal end thereof a pressing tool part for making contact with the upper side of the sheet and forming a product shape in cooperation with the ceiling plate form.
The numerically controlled drive devices are program-controlled to press the pressing tool part against the sheet and move it in this state around the ceiling plate form along a path matching the product shape and also to move the pressing mechanism and the support plate in the plate thickness direction with respect to the ceiling plate form.
With this construction, by means of the cooperative action of the ceiling plate form having a plane shape matching the bottom profile of the product to be formed and the restraining actuators, it is possible to form easily from a sheet a product having a bottom which has a large area of for example about 6 m
2
and also has a complex profile other than a simple polygonal or circular shape, a sharp corner, and a high side wall part continuing at a steep angle from this corner.
Also, because by means of the raising/lowering actuators it is possible to forcibly move the support plate in a forming direction (downward) or an opposite direction (sideward) during progressive forming, sheets of various properties and thicknesses can be formed in an optimal state and can be formed with good accuracy without cracking or deformation of the side wall part occurr
Amino Hiroyuki
Aoyama Susumu
Lu Yan
Matsubara Shigeo
Amino Corporation
Crane Daniel C.
Striker Michael J.
LandOfFree
Apparatus for dieless forming plate materials does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for dieless forming plate materials, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for dieless forming plate materials will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2480415