Metal deforming – By application of fluent medium – or energy field – Using fixed die
Patent
1980-12-17
1983-07-12
Crosby, Gene
Metal deforming
By application of fluent medium, or energy field
Using fixed die
72 7, 364851, B21D 2212
Patent
active
043923682
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an arrangement for presses particularly those intended for forming sheet metal blanks and wherein forming is effected by hydraulic pressure which varies during a pressing operation. Presses of the type here under consideration comprise a pair of relatively movable components which are made to carry out a relative movement during the pressing operation, means for sensing the said movement and generating a control signal which, according to a functional relationship relevant to the pressing operation, depends on the second movement, and a hydraulic system for regulating the hydraulic pressure by means of the central signal so that during the pressing operation hydraulic varies according to the functional relationship. More specifically, the invention relates to an improved arrangement for controlling the hydraulic working pressure which acts in such a press during a pressing operation and which thereby controls, either directly or indirectly, the course of the operation.
THE PRIOR ART
Pressure control of this kind in a press is necessary so that satisfactory working results may be obtained when carrying out deep drawing and similar pressing operations when sheet metal blanks are to be given a complicated form. For this purpose, various solutions may be found on the market, based on drawing a curve which represents on a specific scale the relationship between the hydraulic pressure and the movements carried out, which relationship has been found to be suitable for a pressing operation. A templet is then produced from plate or other rigid material to have a contour that corresponds accurately with the curve, and this templet is fixed to a movable means appertaining to the press which mechanically detects the movements involved. A templet sensor, the sensing part of which follows the contour of the templet and is movable in the lateral direction relative to the displacement direction of the templet, during the pressing operation transmits its lateral movements, obtained from the displacements of the templet to a signal generator in the form of a pressure control valve or a potentiometer which controls an electro-hydraulic valve via an amplifier. The latter arrangement is described in more detail in U.S. Pat. No. 3,962,895.
To establish the relationship between the relative movement and the working pressure which the contour of the templet represents generally calls for a very comprehensive sampling process, particularly for parts with high drawing depth ratio, and it is not unusual before starting series-production for 20 samples to have to be made, with adjustments in between at different points over the contour of the templet before a satisfactory work-piece is obtained. Obviously, a templet cut out of plate is less suitable, but even if a cam plate is used, the contour of which is formed by a steel strip which is adjustable by means of a number of positioning screws connected to the steel strip, such adjustment work is still time-consuming and troublesome and cannot be carried out without tools.
Furthermore, it is difficult to carry out a purely mechanical templet-sensing which is very accurate without the transmitted movement varying from one run to the next due to mechanical imperfections in the signal generating control valve.
A templet-sensing arrangement for hydraulic presses which works with photocells is known from Swedish Pat. No. 322 193. The templet which, as in the above-described arrangement, is displaced by one of the moving components of the press, can be made in this instance from a piece of paper which is cut so that it gives the desired pressure curve and which is then inserted in a holder so that depending on its movement, light from a light source located on one side of the templet is screened from or reaches a row of photocells arranged on the other side. The arrangement requires that every time a new part is to be produced a templet must be made, or the pressure curve adjusted on an existing one if it is not desired to file all the pre
REFERENCES:
patent: 2693780 (1954-11-01), Winter
patent: 3290919 (1966-12-01), Malinak
patent: 3357218 (1967-12-01), Mitchell
patent: 3635061 (1972-01-01), Rydell
patent: 3824574 (1974-07-01), Ironside
patent: 3962895 (1976-06-01), Rydell
patent: 3987283 (1976-10-01), Moeller
berg Ulf
Folkesson Hans
Crosby Gene
Custin James R.
Nilles James E.
Saab-Scania Aktiebolag
LandOfFree
Arrangement for presses does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Arrangement for presses, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Arrangement for presses will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-192677