Hydraulic bending press with movable lower platen

Details Hydraulic bending press with movable lower platen Hydraulic bending press with movable lower platen

1991-08-19

1993-09-14

Hornsby, Harvey C.

Presses

Automatic or material triggered control

Of parallelism of platens

100258A, 72389, B30B 1524

Patent

active

052439020

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to hydraulic bending presses for deformation of sheet metal parts.
More specifically, the invention is concerned with bending presses of the type comprising a stationary upper platen and a movable lower platen actuated by at least three hydraulic jacks, two of which are placed at the lateral ends of the movable platen and at least one of which is placed at the center, these jacks being supplied from a single directional distribution system which controls the upward and downward movements of the movable platen.
2. Description of the Prior Art
Machines of this type have an advantage in that parallel deformation of the opposite edges of the two platens takes place during operation of the press by virtue of the fact that the thrust force exerted by the jacks on the movable lower platen is uniformly distributed along this movable platen in order to form constant and accurate folding angles. This machine geometry is that of machines described in French patent No. 1,362,471. In these machines, guiding means are provided for maintaining the movable platen parallel to the stationary upper platen during its displacements. As a rule, these guide means consist of rotating rollers carried by the movable platen and placed in contact with guide tracks provided on stationary elements of the frame. However, these mechanical guiding means prove to be insufficient in the event that the resultant of the forces generated by the work performed is not located in the axis of the machine. In such a case, the movable platen is in fact subjected to a tilting torque. Under these conditions, by reason of the elasticity of the different parts of the machine as well as the elasticity of the guiding means themselves, these means prove to be incapable of maintaining either general parallelism or parallelism of the opposite edges of the two platens as is required for ensuring angular precision along the entire length of the bend.
The problem of balancing of presses subjected to an eccentric work force has been a matter of concern to both manufacturers and users, whether in the case of plate-type presses for general use or bending presses having a long and narrow platen in which this problem is particularly critical.
The machine to which the invention applies in accordance with the present Application is of a very special type. In fact, it involves the use of a single pressure source, a single distribution for control of movements and at least three working jacks, at least one of which is placed at the center.
The different methods of balancing which have already been developed do not apply to this type of machine and to this configuration of elements. Even in the field of machines to which they do apply, they fail to obtain both a general parallel relationship or parallelism between the two platens and optimization of the parallelism of the opposite faces of the lower and upper platens as is exhibited by the machines in accordance with French patent No. 1,362,471 on condition that the load is centered, that is to say the parallelism which takes into account geometrical deformations of the platens under the action of work forces.
The techniques employed up to the present time are usually concerned with presses having two upper jacks and involve the use of a machine equipped with a unit for servo-distribution by means of a jack. In arrangements of this type, the pressure established within the jack is solely a function of the work reaction which takes place in opposition to the movement of the jack, the servo-distributor being intended to control a volume of oil supplied to the jack.
In devices equipped with two jacks, by reason of the very fact that the number of jacks is limited to two, the basic characteristic of parallel sag of the opposite platen faces, even under centered load conditions, cannot be realized as in the presses in accordance with French patent No. 1,362,471 which describes a technique involving the use of three jacks. Only general paralle

REFERENCES:
patent: 3129625 (1964-04-01), Jones, Jr.
patent: 3550425 (1970-12-01), Cailloux
patent: 3668919 (1972-06-01), Hongo
patent: 4148203 (1979-04-01), Farazandeh et al.
patent: 4366699 (1983-01-01), Tsuchiyama
patent: 4656862 (1987-04-01), Kogure et al.
patent: 4784058 (1988-11-01), Nakagawa et al.
patent: 4819467 (1989-04-01), Graf et al.
patent: 4828474 (1989-05-01), Ballantyne
patent: 4923383 (1990-05-01), Kurumaji et al.

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