Title:
Method and apparatus for forming cup-shaped articles
United States Patent 2292462


Abstract:
The invention relates to forming sheet metal articles from blanks and has for its object a process or method and apparatus for forming sheet metal articles into a predetermined shape by hydraulic pressure applied to one side of the article to press the opposite side against a forming die and...



Inventors:
Milford, Francis H.
Application Number:
US30107539A
Publication Date:
08/11/1942
Filing Date:
10/24/1939
Assignee:
Milford, Francis H.
Primary Class:
Other Classes:
72/372, 72/396
International Classes:
B21D26/041; B21D26/047
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Description:

The invention relates to forming sheet metal articles from blanks and has for its object a process or method and apparatus for forming sheet metal articles into a predetermined shape by hydraulic pressure applied to one side of the article to press the opposite side against a forming die and permitting a gradual release of the pressure, so that the metal, during the forming operation, flows evenly and the strains are distributed evenly throughout the article, as at no time is the blank held more tightly at one point or zone than at another.

The feature of the method and apparatus is the gradual relief of the hydraulic fluid under pressure during the forming operation. In some instances, the hydraulic fluid does not actually run out. In other cases, as in forming cup shaped articles, the fluid gradually releases during the forming operation around the rim of the cup shaped article.

The invention consists in the method and apparatus hereinafter set forth and claimed.

In describing this invention, reference is had to the accompanying drawing in which like characters designate corresponding parts in all the views.

Figures 1 and 2 are longitudinal sectional views of a portion of the apparatus embodying my invention, Figure 1 showing the position of the die element and fluid receptacle at the beginning of the forming operation, and Figure 2 the relative position at the end of the forming operation.

Figure 3 is a sectional view of a blank.

Figure 4 is a view similar to Figure 3 of a blank when formed up into one of the many forms into which the blank may be formed.

Figure 5 is a fragmentary sectional view illustrating the operation on a tubular blank or a blank other than a cup shaped blank.

In its broader aspects, the process consists in applying hydraulic pressure to one side of a hollow blank to press the outer side against a forming die and permitting a gradual relief for the hydraulic fluid along a circumferential line of the surface of the blank to which the hydraulic pressure is applied. With specific reference to a process for forming cup shaped articles, the process consists in applying hydraulic pressure to the closed end of a cup shaped blank while holding the blank or the interior thereof to a predetermined form while it is conforming under the hydraulic fluid or while being pressed against a die on the interior of the blank, by the hydraulic pressure, and permitting the gradual release of the hydraulic fluid around the outside of the open end or rim of the blank during the forming operation.

The apparatus comprises, generally, a die section in the form of a receptacle for receiving a hydraulic fluid under pressure, the receptacle being open at one end, and a die element extending into the former die or receptacle through the open end thereof, the portion in the receptacle being of the contour desired in the finished blank, the die element being spaced at its outer end from the wall of the receptacle to provide a space for the cylindrical wall of the cup shaped blank with the cylindrical wall of the blank fitting, with a small clearance, the wall of the receptacle, in order to permit a gradual escape of hydraulic fluid during the forming operation, all so that when the hydraulic fluid under pressure is supplied to the receptacle, the pressure against the closed end of the blank causes the blank to conform to the contour of the portion of the die element presented in the receptacle, and while the cup-shaped blank is conforming to the die element, the hydraulic fluid is gradually escaping through the restricted clearance. This avoids deforming of the blank and also avoids wrinkling of the blank during the flow of metal thereof, so that the finished article comes out practically smooth.

In the apparatus here illustrated, the die element includes outer and inner concentric sections or members, one of which is axially movable under the hydraulic pressure against a restraining force, and in the illustrated embodiment of my invention, the outer die member is shown as axially movable, although in forming some contours, the inner die member may be axially movable.

I designates the receptacle for a hydraulic fluid under pressure which is supplied thereto from a suitable source through an inlet 2. The die or receptacle is open at one end, usually the upper end. 3 and 4 designate, respectively, the outer and inner members or sections of the die element.

The outer die section, in this embodiment of my invention, is axially shiftable against a spring 5 thrusting at one end against the upper end of the outer section or member 3 and at its upper end against a shoulder 6 on the stem 1 of the inner section or member 4. The die element or the stem 1 of the inner section or member 4 is mounted on a suitable carrier, not shown, capable of shifting the die element, as a whole, into and out of the receptacle I, and holding it therein during the forming operation under the action of the hydraulic fluid. The die element is movable out of the receptacle for the purpose of placing thereon a cup shaped blank as 8 (Figure 3) for removing the fiished blank therefrom. ' 9 designates one form of the finished blank.

The blank 8 may be formed in any manner, as by drawing. Heretofore, the finished blank 9, such as shown in Figure 4, has been formed by drawing operations, and the feature of this invention is that the finished blank is formed by a hydraulic pressure applied to the outer side 1( of the closed end of the blank, while it is in the receptacle and while it is being held in shape by the die element, and also the gradual release of the hydraulic fluid during the forming operation to prevent distortion and wrinkling of the 1( blanks. The die element or the outer member or section thereof extends into the receptacle with an annular space around it and the wall of the receptacle sufficient to receive the upper end of the cylindrical wall of the blank 8 but 2( leaving a small restricted clearance or crevice at 10 sufficient to permit the gradual release of the hydraulic fluid under pressure during the forming operation.

After the blank 8 has been placed on the die 2{ element and the die element moved into the receptacle I into the position shown in Figure 1, the hydraulic fluid is supplied to the receptacle under pressure, and applies pressure to the closed end 11 of the blank, causing it to move upwardly, and while the pressure continues to be applied, to thrust the axially movable die member or section which, in this instance, is the outer die member or section 3, upwardly toward and into the position shown in Figure 2, thus causing the inner die member 4 to protrude further beyond the end of the outer die member or section 3, and the closed end of the blank to conform to the contour of the lower end of the die member 4, the hydraulic fluid, during this operating, gradually escaping through the small clearance 10.

In Figure 5 is illustrated a die for forming, by hydraulic pressure, a tubular blank with peripheral corrugations, as threads, in which the hydraulic pressure is applied to the inner face of the tubular blank to press the outer face against the forming die provided with grooves for forming the threads and providing relief for the hydraulic pressure. la designates the forming die element which is composed of opposing members or sections shiftable toward and from each other. 12 designates the die through which the hydraulic pressure is applied, this having passages 13 and 14 for the hydraulic fluid under pressure. 15 designates the tubular blank to be provided with corrugations or threads. The die element la is provided with suitable cavities 16 for forming the corrugations or threads, when sufficient hydraulic pressure is applied to the inner face of the tubular blank through the passages 13 and 14. The die member 12 slidably fits the inner face of the tubular blank in contradistinction to tightly fitting, thereby providing a gradual relief for the hydraulic pressure at I7 throughout the circumferential line of the inner face of the tubular blank.

In operation, the tubular blank may be easily slipped on the die section 12 and removed therefrom after the forming operation by separating the sections of the forming die I1. The corrugations may be formed to the full depth of the cavities 16, if desired, or any intermediate depth by varying the hydraulic pressure. In any case, the blank not being clamped or held tightly at any point, the pressure is not localized, but on the contrary, is distributed evenly throughout the blank, and hence the metal of the blank flows evenly during the forming operation.

Owing to the gradual release of the hydraulic fluid, deforming of the blank is avoided, and also the metal of the blank flows smoothly and does not leave wrinkles, corrugations, or other dis0 tortions and imperfections. In some forms, the inner die member or section may move axially, so that the closed end of the die takes the reverse of its original form, or goes through a sort of turning inside out movement during the Sforming operation. In any case, the hydraulic fluid pressure is applied to the outer closed end of the blank and the hydraulic fluid escapes around the rim of the blank during the forming operation.

0 What I claim is: 1. A forming apparatus comprising a receptacle for receiving a hydraulic fluid under pressure, the receptacle being open at one end, a die element extending into the receptacle Sthrough the open end, the portion located in the receptacle receiving a cup shaped blank with the closed end portion of the blank exposed in the receptacle and the circumferential wall of the blank also fitting the wall of the receptacle Swith a sufficient clearance to permit the gradual relief of the hydraulic fluid when under pressure, said die element including outer and inner concentric sections, the outer section having an axial movement relative to the inner, under the hydraulic pressure against the closed end of the blank while the blank is forming, whereby when the hydraulic fluid under pressure is supplied to the receptacle, the pressure at the closed end of the blank causes the blank to conform to the Sdie members and the outer die member and the blank to move axially outward relative to the inner die member and the hydraulic fluid to gradually release from the receptacle around the blank.

2. A forming apparatus comprising a receptacle for receiving a hydraulic fluid under pressure, the receptacle being open at one end, a die element extending into the receptacle through the open end, the portion located in the receptacle receiving a cup shaped blank with the closed end portion of the blank exposed in the receptacle and the circumferential wall of the blank also fitting the wall of the receptacle with a sufficient clearance to permit the gradual relief of the hydraulic fluid when under pressure, said die element including outer and inner concentric sections, the outer section having an axial movement relative to the inner, under the hydraulic pressure against the closed end of the blank while the blank is forming, whereby when the hydraulic fluid under pressure is supplied to the receptacle, the pressure in the closed end of the blank causes the blank to conform to the die members and the outer die member and the blank to move axially outward relative to the inner die member and the hydraulic fluid to gradually release from the receptacle around the blank, and means for yieldingly restraining the outward axial shifting of the outer die element.

3. A forming apparatus comprising a receptacle for receiving a hydraulic fluid under pressure, a die element including outer and inner concentric die members extending into the receptacle to receive a cup shaped blank, one die member being movable axially relative to the other, and means for yieldingly restraining such axial movement, the outer die member being spaced from the wall of the receptacle providing a space for the cylindrical wall of the cup shaped blank with the cylindrical wall fitting with a small clearance the wall of the receptacle to permit gradual relief of the hydraulic fluid during the forming operation, all whereby when the hydraulic fluid under pressure is supplied to the receptacle the pressure against the closed end of the blank causes the axially movable die member to move outwardly relatively to the other die member while the blank is being conformed by the hydraulic pressure to the die members.

4. The process of forming articles from sheet metal cup-shaped blanks consisting in pressing the closed end portion of the blank against a die of predetermined form in the interior of the blank by hydraulic pressure applied to the outside of the closed end portion in a receptacle to which hydraulic fluid under pressure is being applied, effecting the relative axial movement of the die with the blank thereon and the receptacle and hydraulic fluid therein, and permitting a gradual, continuous outflow of the hydraulic fluid around the outside of the rim of the blank through a clearance between the circumference of the blank and the wall of the receptacle during the forming operation and while forcing the die and blank into the receptacle, and while hydraulic fluid under.pressure is being supplied to the receptacle.

5. The process of forming articles from sheet metal blanks consisting in applying hydraulic pressure to one side of the blank to press.the opposite side against a forming die, confining the hydraulic pressure to said one side and permitting a gradual release of the pressure throughout the circumference line of the surface to which the hydraulic pressure is applied.

6. An apparatus for forming articles from sheet metal blanks comprising coacting die members, to one of which the blank eventually conforms, the other die member fitting the blank with sufficient clearance to permit a gradual release of fluid under pressure circumferentlally of the latter die, and means for applying hydraulic pressure to the blank from the latter die member against the blank and through said clearance.

FRANCIS H. MILFORD.