Boots – shoes – and leggings
Patent
1991-04-29
1993-12-21
Smith, Jerry
Boots, shoes, and leggings
72380, 72389, G06F 1546, B21D 502, B30B 1518
Patent
active
052726436
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates generally to an apparatus for controlling a press brake. More particularly, the present invention relates to an apparatus for controlling a press brake wherein a plate is bent to a required bend angle with a high accuracy in additional consideration of mechanical deformation of the press brake caused by a bending operation performed for the plate.
BACKGROUND ART
As shown in FIG. 6 and FIG. 7, a press brake c includes a lower beam e on which a die a having a V-shaped sectional contour is fixedly mounted and an upper beam d on which a punch b is fixedly mounted so that a plate f is bent by lowering the upper beam d. As the plate is bent in this way, the upper beam d is deflected upwardly and the lower beam e is deflected downwardly during the bending operation under the influence of a load exerted on the upper beam d and the lower beam e, as represented by one-dot chain lines in FIG. 7. As a result, there is caused a phenomenon of so-called intermediate opening that a bend angle .theta..sub.2 of the plate f becomes larger than a bend angle .theta..sub.1 at opposite ends of the plate f because of the aforementioned deflection (refer to FIG. 8).
To prevent the phenomenon of intermediate opening from being caused, a measure of crowning adjustment is taken such that the central part of the die as viewed in the longitudinal direction is previously bent upwardly as represented by a two-dot chain line in FIG. 7 to maintain a parallel relationship between the upper beam d and the lower beam during the bending operation. Such a crowning adjustment mechanism as mentioned above has been already known as an apparatus for eliminating a malfunction of so-called intermediate opening in a press brake wherein the apparatus is disclosed in an official gazette of Japanese Patent Publication NO. 47017/1985 of which patent application was filed by the common applicant to the present invention.
When the plate f is to be bent to a required bend angle by operating the press brake c, it is required that a so-called quantity of driving g, i.e., a distance between the upper end of the die a and the lower end of the punch b is correctly determined corresponding to the required bend angle. In view of the fact that the driving quantity g is definitely determined by presetting the lowermost position of the punch b, the press brake is equipped with a mechanism for adjusting a quantity of downward stroke of the upper beam d so that the downward stroke quantity of the upper beam d is set to an optimum value corresponding to the required bend angle with the aid of the foregoing adjusting mechanism. This kind of technology has been already known as an apparatus for controlling a bend angle in a press brake wherein the apparatus is disclosed in an official gazette of Japanese Patent Publication NO. 20927/1989.
According to the foregoing prior invention, working conditions associated with a required bend angle of a plate, a thickness of the plate and others are inputted into the apparatus so that a value of correction to be accomplished for the driving quantity is obtained based on the working conditions in additional consideration of mechanical characteristics of the press brake and elastic deformation characteristics of the plate and the corrected driving quantity is then obtained based on the corrected value of the driving quantity and the logical value derived from the driving quantity, whereby the lowermost position to be assumed by the punch is set corresponding to the corrected driving quantity.
With respect to the first-mentioned prior invention relating to a mechanism for adjusting a quantity of crowning, however, it has been found that the mechanism has the following drawback. Specifically, a quantity of crowning to be adjusted varies in correspondence to a quantity of deflection of each of the upper beam d and the lower beam e. In view of the fact that the deflection quantity varies depending on the working conditions associated with a bending operation, an operator usually performs tr
REFERENCES:
patent: 4620435 (1986-11-01), Gabella et al.
Gordon Paul
Kabushiki Kaisha Komatsu Seisakusho
Smith Jerry
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