Metal deforming – By use of closed-die and coacting work-forcer – Cup or shell drawing
Patent
1998-08-17
2000-03-07
Larson, Lowell A.
Metal deforming
By use of closed-die and coacting work-forcer
Cup or shell drawing
7245313, B21D 2408
Patent
active
060325062
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the field of stamping tools working on a hydraulic or mechanical press. It relates more particularly to the blank-holder force-regulating system in a stamping press.
A stamping press essentially comprises a table to which a die with an impression is fixed, the profile of which is that of the external surface of the component to be stamped, a blank holder serving to fix the sheet blank to be stamped, and a punch fixed to the ram of the press, this punch having a complementary profile to that of the impression of the die. When the punch exerts pressure on a blank placed over the die, it deforms the blank in the gap between the die and the punch.
The blank holder exerts a clamping pressure on the faces of the blank for the purpose of preventing the sheet wrinkling due to the shrinkage effect. The clamping pressure exerted by the blank holder may furthermore serve to create a high tensile stress in the skirt of stampings in the case of tapered stampings, or for setting up, by drawing on the punch for example.
European Patent No. 0,475,923 discloses a system which allows the blank-holder force to be rapidly varied and essentially to be regulated automatically on the basis of significant parameters of the stamping process.
When this system is used on a cushion of a hydraulic or mechanical press, the cushion force is chosen to be greater than the maximum blank-holder force exerted in the context of regulation and this force is exerted against thrust bearings which bear on that part of the tool which is connected to the moveable ram of the press. The force exerted by the cushion therefore serves in this case only to close the tooling, the effective, blank-holder pressure being exerted by small cylinders placed in the tooling. However, in industrial practice, there are situations in which it is not necessary to use the blank-holder force-regulating system over the entire area of the blank holder--a constant blank-holder pressure may be applied over a major area of the blank holder, as in conventional tools (this area being hereinafter called the conventional blank-holder area)--and a variable blank-holder pressure may be applied in one or more specific areas only, these being hereinafter called the blank-holder pressure-regulating areas. The present invention relates to these industrial situations.
To achieve this objective, the invention provides a blank-holder force-regulating system in which the variation in the force in the blank-holder pressure-regulating areas is compensated so as to maintain a predetermined constant pressure in the conventional blank-holder area. This pressure in the conventional blank-holder area can, by virtue of the present invention, according to certain alternative embodiments, also be made to vary.
The blank-holder force-regulating system according to the invention is defined in the claims.
The invention and an illustrative embodiment are described in greater detail below with the aid of the appended drawings.
FIG. 1 represents a front view of a typical stamping press in which the invention is incorporated, the press being open, before stamping.
FIG. 2 represents the same press closed at the end of stamping.
FIG. 3 is a diagram indicating the forces involved in the process according to the invention.
FIGS. 4, 5 and 6 show alternative illustrative embodiments of the invention .
In FIG. 1, the reference number 1 denotes the movable ram of a stamping press, the number 2 denotes the die fixed to the ram, the die having in hollow form the shape of the component to be stamped, the number 3 denotes the blank holder and the number 4 denotes a component for supporting the blank holder, which component 4 bears directly or indirectly, for example by means of columns 8 through the table 10, on the cushion of the press. For simplicity, this component 4 will hereinafter be referred to by the term "cushion". In this arrangement, the punch 9 is stationary and rests on the table 10 of the press, passing through the opening in the blank holder 3. The sheet to be stamped
REFERENCES:
patent: 1970134 (1934-08-01), Ferris
patent: 4036056 (1977-07-01), Saunders
patent: 4635466 (1987-01-01), Seki et al.
patent: 4745792 (1988-05-01), Story et al.
patent: 5623848 (1997-04-01), Kirii
Cockerill Sambre Campus Universitaire du Sart-Tilman
Larson Lowell A.
Meroni, Jr. Charles F.
S.C. Recherche et Developpement Groupe
LandOfFree
Improvment to the blank holder force regulating system in a pres does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Improvment to the blank holder force regulating system in a pres, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Improvment to the blank holder force regulating system in a pres will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-352654