FR2709081A1 - Improved safety in the use of aluminium aerosol cans - Google Patents

Abstract

The invention consists of the provision of a recess located at 4 on the bottom 5 of the can 3. Fig. 1. During the various phases of deep-drawing the bottom 5, the latter adopts a concave shape and the recess 4 closes up, strengthening the line of rupture. On test, under pressure, the bottom 5 assumes a convex shape and partially releases that part of the bottom bounded by the recess 4.

Description

 The present invention relates generally to an improvement made in the manufacture of pressurized aerosols, by producing a calibrated rupture initiator, always on the bottom of the container, thereby improving safety in use.

 During tests of resistance to the bursting pressure of the aluminum boxes obtained by spinning, there is a first phase, the bottom of the concave case deforms and becomes domed, second phase, the case bursts on its periphery randomly.

 The object of the present invention is to obtain a controlled rupture, at the base of the case, when the bottom has become convex by forming a notch on the bottom of the said case.

 The advantages of this process are: rupture, in the event of overpressure, always in the same place - saving of material by reducing the thickness of the bottom. Only the bottom of the stamping die is to be arranged.

 This process is different from patent 2.308441 which applies to a system for easy opening of containers from pre-varnished metal sheets.

Similarly, patent 3.310170, claim 2, applies to sheet metal by the design of the tooling.

 The features and advantages of the tool according to this invention will appear better in the detailed description made with reference to the appended drawings.

 A cylindrical aerosol can, monobloc, made of aluminum is obtained by stamping an aluminum pellet of appropriate diameter on a press comprising a matrix and a piston which makes it possible to shape at the exit of spinning, a cylindrical container with flat bottom which is then treated. at different stations to obtain the desired final presentation with the usual concave bottom.

 The invention consists in forming a cylindrical notch on the outside bottom of the case, when spinning.

 - Figure 1 is a cross-sectional view of the die used to execute the notch with positioning of the piston at the end of spinning.

 - Figure 2 is a sectional view at high magnification of the notch made on the bottom of the blank.

 - Figure 3 is a sectional view at high magnification of the concave housing bottom in the last stamping phase of the base.

 - Figure 4 is a sectional view of a finished housing.

 - Figure 5 is a bottom view of a finished case.

 This tool comprises, in FIG. 1, an improved die 1, comprising a punch 4 and a piston 2 unchanged in its shape, between which the aluminum chip is placed to obtain, by spinning, the case 3 with bottom 5.

 Figure 2 shows the notch formed by the circular punch whose angle obtained on the lip 6 is about 350 relative to the axis of the die, and the lip 7 inclined at 100 to obtain a correct clearance of the 'draft.

 FIG. 3 shows the bottom 5 of the case 3, which has become concave, in the last stamping phase and with the existing tools.

 The punch 4 must be positioned in the concave part of the finished base 5 as indicated in 8.

 During the different stamping and pushing back phases, the lines 6 and 7 will join to form a connection line 8 in which the lip 6 will have formed a re-entrant angle relative to the axis of the housing. This arrangement strengthens the bottom resistance.

 During the bursting resistance test, the bottom 5 will bulge apart the lips 6 and 7 which will tend to resume their initial shape, the weakening line 8 will thus be cleared to allow its rupture.

 FIG. 4 represents in section a case 3 finished with its concave bottom 5 obtained during the different stamping phases and the breaking line 8.

 The positioning of the notch 8 is determined by the diameter of the housing 3 and the shape of the concave radii of the last deep-drawing tool 5.

 Figure 5 shows the bottom 5 on which the line 8 has a notch interruption 9 which will form a hinge at the time of bursting. The purpose of this arrangement is to prevent the projection of the metal torn off.

Claims (3)

 1) Improved tooling to form a break notch on cylindrical aluminum monoblock aerosol cans.  2) Improved tools for forming a breaking notch on containers with concave metal panels obtained by spinning and stamping.  3) Improved tools according to claims 1 and 2 adaptable to all forms of panels obtained by drawing concave stamping.