GB2065527A

GB2065527A - Method and apparatus for forming the mouth rim of a resealable can

Info

Publication number: GB2065527A
Application number: GB8027231A
Authority: GB
Original assignee: MALAGUENA METALGRAFICA
Current assignee: MALAGUENA METALGRAFICA
Priority date: 1979-12-11
Filing date: 1980-08-21
Publication date: 1981-07-01
Also published as: PT71457A; ES486785A1; FR2471234A1; ZA805369B; MA18876A1; IT8023281A0; IT1132515B; GR69194B

Abstract

A can mouth rim is formed integrally with the main side wall of the can by inward deformation of one end of a sleeve blank (1) to preform a flange (3) for subsequent shaping to form the mouth rim as the other end of the sleeve blank is deformed outwardly to form the conventional flange (2) for receiving a crimped or "closed end" type of can end. <IMAGE>

Description

SPECIFICATION Method and apparatus for forming the mouth rim of a resealable can The present invention refers to a method of forming the mouth rim of a metallic can of the type having a pan shaped closure lid which can be levered out of the mouth rim, and subsequently pressed back into position for resealing the can. This forming operation imparts to the mouth rim a shape similar or a shape appropriate for receiving the generally metallic lid which must be a force fit in the rim in order to seal the can and thereby to prevent the contents from deteriorating. Such cans are, for example, used for packing paints or other similar products.

Such metallic cans, preferably metallic ones made out of tin plate, white iron, or aluminium, are made starting from a metallic laminated strip which is rolled and seamed, for example by thermoelectric fusion, to make it tube-shaped in any suitable cross-section, for example cylindrical, square, rectangular or oval. The side seam of the sleeve blank has been sealed by adhesives or solder at the seam.

Once the blank has been cut to allow for the desired height of the finished can, both ends of the sleeve are flanged outward. The can ends are fitted over the outwardly extending flanges and fastened by a traditional crimping system with the incorporation of an airtight sealing compound made out of rubber or plastic jointing material.

One of these two can ends has been stamped concentrically, in such a way that a mouth with a cross-section smaller than the vessel section has been produced. This mouth has a rim made up by a shape which generally comprises a double rib terminating in a radially inwardly disposed deep skirt extending axially inwardly of the can creating a mouthpiece with a given height for receiving the lid. The lid itself is also stamped, in the shape of a pan, and is force fitted in the can mouth so as to be removable (by prising away from the mouth rim) and replaceable (for resealing the cam).

The above described operative phases in the usual process for the development and manufacturing of a resealable type of can are very well known.

According to one aspect of the present invention we provide a method of shaping the mouth rim of a can body having a removable force-fitted closure lid to fit the mouth rim, comprising taking a sleeve blank for a can body having an axial length appropriate to the height of the finished can; deforming one end of the sleeve blank outwardly to form a flange to enable a "closed end" of the can to be crimped in place; deforming the other end of the sleeve blank inwardly to preform a flange capable of shaping to form the mouth rim to receive the replaceable can lid, the radial dimension of the inward flange at said other end being greater than that of the outward flange at the said one end; and then shaping the said inward flange at the said other end to have a reinforced cross section in order to receive the said lid.

According to another aspect of the invention we provide apparatus for forming the mouth rim of a can, comprising a press having (a) first and second die member co-operating to define, in a "press closed" configuration, a cavity having an annular inlet portion opening into a transversely extending inner portion extending radially inwardly of the annulus of said inlet portion, said first die member being a male die member and being carried by the drive punch of the press for movement towards and away from the second die member which is a female die member, and (b) a male third die member spaced from said first die member but carried by said drive punch for collinear movement of said first and third die members, wherein said third die member includes a die surface shaped to deform the end of a sleeve blank outwardly during movement of the drive punch towards said "press closed" configuration, the arrangement being such that a sleeve blank may be positioned with one end in said inlet portion of said die cavity and its other end engaging said die surface of the said third die member.

With this invention a single pressing operation on the two end of a single sleeve blank can form simultaneously the inward flange for the mouth rim and the outward flange for crimping on a closed can end at the opposite end of the blank.

The inward flange is larger, i.e. fuller, than the outward flange and it consists of, at least, a development no smaller than is necessary for the reinforced cross section, for example including a double rib, for forming the mouth rim.

The said inward flange is mainly in the form of a flat shape at 90 towards the inside.

The final shaping of the mouth rim from said inward flange may be carried out in a subsequent operation or simultaneously with the preforming.

In order that the present invention may more readily be understood the following description is given, merely by way of example, of one example of the shaping of said edge or mouth. Reference will be made to the accompanying rather schematic drawings in which: Figure 1 is a schematic vertical section of one possible set of tools for carrying out the first flanging operation; Figure 2 is a view analogous to Fig. 1, but showing one possible set of tools for carrying out the second operation, i.e. the ribbing of the mouth; and Figure 3 is a vertical sectional detail of the cross section of the mouth of one embodiment of can according to the invention.

Referring now to the drawings, Fig. 1 shows the simultaneous flanging operations on the ends of the side seamed sleeve bank, namely outward flanging (in the traditional manner) at the "closed end" and inward flanging (according to the invention) at the open end". Fig. 1 shows a can blank sleeve 1 which is to be provided with the conventional outward flange 2 in order to receive a can end (of the "closed end" type) by the traditional crimping system. Fig. 1 shows at the bottom of the blank 1 the inward flange 2 which, according to the invention, is made integrally with the sleeve blank 1 and is intended to define the mouth rim.

It is to be understood that the stroke of the drive punch 4 of the press fulfills the double task of oppositely directed flanging at the respective two ends of the blank almost at the same time. The drive punch 4 has an extension piece 7 which carries axially slidably at its upper part a male die member 5 provided at its periphery with the shaping surface 6 for forming the outward flange 2 and, at its lower part it is equipped with a further male die member 9 connected thereto by conventional means such as threading and a spacer washer.

This further male die member 9 forms with the lower female die 11 a recess which has an inlet A to receive the lower end of the sleeve blank 1 and which extends axially to join an almost flat cut cavity B for the shaping of the inward flange 3.

The cavity B is defined between the raised rim 10 of the further male die member 9 and a channel 12 of the lower female die 11, the rim 10 and channel 12 being complementary to one another but separated in the closed configuration of the die members 9 and 11 by the inlet gap A and the cavity B whose widths are equivalent to the thickness of the can sleeve blank 1, but with a small tolerance.

The substantially simultaneous shaping of the outward flange 2 and the inward flage 3 is done in the following manner. The tubeshaped sleeve blank 1 initially has its lower end fitted into the female die member 11.

When the drive punch 4 advances to start its stroke, the lower male die member 9 remains coupled and, almost at the same time (the sequencing being controlled by times and pressures as in similar pressing systems), the upper male die 6 begins to shape the outward flange 2 and thrusts the sleeve blank downwardly to form the inward flange 3 which acquires its shape in the cavity B. This downward movement of the sleeve blank continues until the end edge of the sleeve blank 1 strikes the radially inner side wall of the channel 12 of the female die member 11.

This channel side wall defines a stop acting as the rivet-dolly for finishing off the outward flange 2.

Raising of the punch 4 lifts the lower male die member 9 while the slidable fit of the upper male die 8 on the extension piece 7 of the punch 4 enables the flanged sleeve blank 1 to be held down on the female die member 11 to facilitate stripping of the blank 1 from the punch dies 5, 9.

The pre-shaped outward flange 3 is next subjected to an edging, or double rimming, operation illustrated in Fig. 2 in order to construct the cross section shown in Fig. 3.

This edging is achieved by means of a different type of lower male die 13 which has its cross section 14 adapted to the raised rim which it is desired to produce in the inward flange 3. This die is substantially an annular body 1 3a having a radially inner cylindrical wall 1 3b to allow the shaping of the deep inner skirt 21 (Fig. 3) of the mouth rim of the container 1 9.

This pressing operation is carried out on a female die member 15 which has a rib 16 and a radially outer step 17 shaped to make it easier for the material to be released once it is pressed out of the female die member 15.

This female die member 15 is only a simple example of a suitable pressing die.

Both the preforming of inward flange 3 and its final shaping can be carried out substantially simultaneously in order to take better advantage of the manufacturing time. For example, it may be possible to combine, in a single press, the tooling for preforming and final shaping or even to design one set of lower die members to carry out both steps.

Fig. 3 shows a detail, in vertical section, of a can body provided at one end with the outward flange 2 in order to receive a "closed" can end by conventional crimping and at its opposite end with a mouth rim consisting of ribs 20 with the skirt 21 of the mouth 19 already shaped to receive under pressure a removable lid of the traditional pan shape.

It is easy to understand that the method of the present invention makes it possible to simplify substantially the manufacturing operations, since it eliminates the traditional independent pressing of the lid-receiving mouth rim and its subsequent crimping to the can sleeve blank. It also eliminates the loss of material resulting from stamping the mouth rim and from crimping it to the can sleeve blank, although the saving of material by not having to crimp the mouth rim in place is in part offset by the longer length that the can sleeve blank 1 needs in order to allow for shaping the inward flange 3.

The sealing of the crimping joint of the mouth rim to the sleeve blank 1 is saved, given that there is no such crimping and substantial working time is saved.

It will be understood that the final shape of the inward flange 3 (shown in Fig. 3) made by the tools of Fig. 2 once the inward flange 3 has been preformed, could be obtained with other tooling for the final shaping operation.

It will of course be understood that although in the preferred embodiment illustrated, the can body and the mouth rim are both circular in cross section, some other section could instead be provided by suitable shaping of the press dies.

Claims

1. A method of shaping the mouth rim of a can body having a removable force-fitted closure lid to fit the mouth rim, comprising taking a sleeve blank for a can body having an axial length appropriate to the height of the finished can; deforming one end of the sleeve blank outwardly to form a flange to enable a "closed end" of the can to be crimped in place; deforming the other end of the sleeve blank inwardly to preform a flange capable of shaping to form the mouth rim to receive the replaceable can lid, the radial dimension of the inward flange at said other end being greater than that of the outward flange at the said one end; and then shaping the said inward flange at the said other end to have a reinforced cross section in order to receive the said lid.

2. A method according to claim 1, wherein said flanges at the one and the other end are formed simultaneously.

3. A method according to claim 1 or 2, wherein said inward flange at said other end is obtained by applying axial thrust to said one end.

4. A method according to claim 3, wherein said axial thrust is applied using a progressive-acting press on said other end.

5. A method according to claim 4, wherein said press is made up of two closed die members, one male and one female, which together define a die cavity with an inlet for the sleeve blank body having a width related to the thickness of the sleeve blank body, said die cavity having a limited radially inwardly directed extent defined by a flatbottomed channel in the female die member and a complementary edge of the male die member such that the spacing of said channel bottom from the said male die edge corresponds to the thickness of the inward flange to be obtained and that the limited radially inwardly directed extent of the cavity corresponds to the shape of the flange necessary to allow for folding of the flange to form the mouth rim.

6. A method according to any one of the preceding claims, wherein the final shaping operation shapes the reinforced connection as a double rib and an inner skirt for receiving the said closure lid and is carried out using a female die member to receive said inward flange and provided with a profile to shape a channel within the double rib and having a runoff to form said skirt for the inward flange, and a male die member mounted on the drive punch of the press for axially penetrating the inside of the sleeve blank to press on the inside of the inward flange in order to shape the double rib and skirt.

7. A method according to any one of the preceding claims, wherein said preforming of the inward flange and the final shaping of the reinforced cross section of the inward flange are carried out in a single pressing operation with combined die members.

8. A method according to any one of the preceding claims wherein said inward flange is a flat flange perpendicular to the side wall of the sleeve blank.

9. A method of forming a mouth rim of a can, substantially as hereinbefore described with reference to the accompanying drawings.

10. Apparatus for forming the mouth rim of a can, comprising a press having (a) first and second die members co-operating to define, in a "press closed" configuration, a cavity having an annular inlet portion opening into a transversely extending inner portion extending radially inwardly of the annulus of said inlet portion said first die member being a male die member and being carried by the drive punch of the press for movement towards and away from the second die member which is a female die member, and (b) a male third die member spaced from said first die member but carried by said drive punch for collinear movement of said first and third die members, wherein said third die member includes a die surface shaped to deform the end of a sleeve blank outwardly during movement of the drive punch towards said "press closed" configuration, the arrangement being such that a sleeve blank may be positioned with one end in said inlet portion of said die cavity and its other end engaging said die surface of the said third die member.

11. Apparatus for forming a mouth rim of a can, such apparatus being constructed and adapted to operate substantially as herein be fore described with reference to, and as illustrated in, the accompanying drawings.

12. A can formed by the method of any one of claims 1 to 9 or with the apparatus of claim 10 or claim 11.