US2130699A - Method for the production of lightmetal flasks with thickened neck parts - Google Patents

Description

Sept. 20, 1938. H, R NA Z' 2,130,699

METHOD FOR THE PRODUCTION OF LIGHT METAL FLASKS WITH THICKENED NECK'PARTS Filed-Nov. 12, 1937 1 71.3. fig. 4.

Patented Sept. 20, 1938- mm 1 STATE mrrnon FOR 'rnn raonocnon or non-rmmn. msxs wrrn 'rnrcxnnnn NECK PARTS Heinrich Relnarts, Aachen, Germany, assignmmac-halt to Hans Amlaldern, Vienna, Ans- A pplicatlon November 12, 1937, Serial No. 174,148 In Germany July 2, 193B 2 Claims. :(ci. 29-1482) This invention relates to a method tor the production of flasks of light-metal for liquids and gases under high tension. .The neck-portion of such flasks is weakened'thereby that a screwthread has to be cut in; To avoid this weakening it is advisable to make thicker than the other wall only the wall of the neck of the flask, in

order to keep as light as possible the weight of such flasks and so that after the screw thread has been cut into the neck the thickness of the wall of the neck at least corresponds to the thickness of the remaining wall portions.

In order to make the neck of steel bottles Ithicker, it has already been proposed to press .15 onto the open end or the preliminarily drawn cylindrical hollow body, in embracing the same by an insert-die, a press head in axial direction, by the shape of whichthe en'd of the hollow body is transformed into the shape of a bottle neck.

20 During the reducing oi the upper diameter of the hollow body an upsetting of the material in itself takes place and thereby an increase of the wall thickness.

Up to the present the hollow body of a steel 25 bottle was continuously cylindrical prior to the re-shaping or the neck, or its upper partwas thicker. Experiments have shown that, already with continuous cylindrical hollow bodies of light metal the radial resistance at the upper end of the bottle becomes so great that the hollow body especially within the insert-die yields in inward direction in undulated shape, whereas an appreciable'thickening in the bottle neck does not occur at all. If the upper end of a bottle of lightmetal would be thickened prior to the re-shapw ing, the radial pressing resistance would be considerably increased, so that also the wave-tormation within the insert-die occurs in increased measure. Owing to the narrowing. of the crosssection .and accumulation of the material in the neck part a fold formation occurs further. By experiments it has been ascertained that these inconveniences can be avoided in light metal flasks in a quite-peculiar manner, if aca cording to the inventlon the upper portion or the flask is made conically thinner prior to the reshapin and the drawingin of the bottle neck is carried out in several stages in such a manner that first the narrowing at the point of the thinning is completed which is farthest distant from the end of the hollow body, then in the middie and finally in the upper portion. The radial resistance or the wall surface against the narrowingis thereby gradually reduced from the 55 point which has to be least narrowed up to the point which has to be narrowed most, and the axial pressure upon the wall not tobe re-shaped is reduced also.

, The new method is illustrated by way of example in the accompanying drawing, in which I Fig. 1 shows the hollow body with the upper end conically thinner at the outer side.

Fig. 2 shows the hollow body after the first 5 narrowing,

' Fig. 3 after the second narrowing and Fig. 4 after the third narrowing.

It must evidently be left to those skilled in the art to select three or more narrowing. stages 10 according to the size of the flasks. For carrying out the new method as many diflerently shaped press-heads are required as narrowing stages exist. The first press head a engages only on the point of the conically thinned wall which has to be narrowed least, whereby at this point a thickening of the wall occurs approximately on the distance 12 of Fig. 2. The second press head c effects a thickening of the wall approximately on the distance d of Fig. 3. The third press head 2 gives to the bottle neck the final shape, the thickening taking place particularly on the distance of Fig. .4. .Prior to every narrowing the bottle neck is heated to about 400. The new method can evidently be employed with all metals which relative to the narrowing behave in a similar man her as aluminium-alloy.

I claim:

1. A'method for the production of light metal flasks with a thickened neck portion for liquids and gases under high tension from a preliminarily drawn cylindrical hollow body, consisting in first reducing the cross sectional area of the upper portion of the hollow body and conically forming the same prior to the reshaping, and axially and radially compressing the conical end of the hollow body and thereby reducing the same to neck formation in sequential steps in transverse zones toward the end of the neck and thereby moving the material of the conical end 40 to produce a neck wall thickness greater than the thickness of the wall of the flask.

2. A method for producing a cylindrical'metal container with a relatively thick walled neck' and a thin side wall of substantially minimum thickness to withstand predetermined high pres? sure of liquids or gases consisting in first reducing the'thickness of the neck end of the cylinder into end tapering conical formation and then axially and radially compressing the conical end into a smaller diameter by pressing at a transverse zone inwardly of the conical end to increase the wall thickness 0! the neck portion and successively pressing the conical end at transverse zones toward the outer end of the neck.

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