DK146679B - RETAIL CONNECTION FOR FIXING A PIECE WITH NON-WELDABLE SURFACE TO ANY PARALLEL DIMAGE WITH WELDABLE SURFACE AND PROCEDURE FOR MAKING SUCH A RIVER CONNECTION - Google Patents

Description

(19) DENMARK (W)

dg PRESENTATION SCRIPT («> 146679 B

DIRECTORATE OF

THE PATENT AND TRADEMARKET SYSTEM

(21) Patent Application No. 0895/69 (51) Int.CI.3: B 21 D 51/38 (22) Filing Date: 18 »eb 1969 B23K 1/00 (41) Aim. available: 19 Aug 1970 (44) Submitted: 05 dee 1983 (86) International Application No: - (30) Priority: - (71) Applicant: A / S * HAUSTRUPS FABRIKER; 5100 Odense, DK.

(72) Inventor: Børge 'Lundtoft; DK, Axel August 'Age; DK.

(74) Plenipotentiary: The engineering firm Budde, Schou & Co (54) Rivet connection for attaching a plate with non-solderable surface to a parallel case with solderable surface and method for making such rivet connection in

BACKGROUND OF THE INVENTION The present invention relates to a rivet connection for attaching a non-solderable surface plate to a parallel solderable can lid, which includes a soldered rivet formed through a hole in the plate member and has a riveted head in contact with the surface of the canopy facing away from the can lid.

Such fasteners of cans for cans are particularly useful in the manufacture of cans which are 0 arranged to be easily opened by the application of a pull in a pull tab designed as a pull tab attached to a tear. particular field at one end of the can. For attaching such a pull tab to the can end, it has previously been proposed to provide a rivet joint, the rivet being an integral part of the can end. In this known method, a strong deformation of both the can of the can end and the pull tab is made during the fastening operation, which results in a satisfactory result when this material is made of aluminum, while the method, when used in conjunction with white tin materials, causes significant disadvantages such as a severe material deformation and risk of cracking and consequent leakage in the can. However, pieces of white-look material can be joined together in a known way by soldering, welding or bonding. However, normal solder joints are not sufficiently strong in many applications, while welding can easily obtain a sufficiently strong joint, however, causing other serious drawbacks such as burnout and consequent leakage at the can ends or heat damage of any lacquer layer.

An attachment of a plate piece to a can lid is also required when attaching a sacrificial material in the form of an aluminum anode inside a can to provide an electrolytic protection of the can, which is particularly important when the can is used for packaging processed foods. such as ham which can be discolored due to electrolytic corrosion of the can.

The prior art rivet compound mentioned above may also be used in this attachment, although it is most preferred to shrink the anode at the can end. However, both by such shrinkage and by the above-mentioned known methods, the strong deformation of the can end material can cause degradation of the can content.

Further, from the disclosure of English Patent No. 224,044, there is known a method for joining two metal plates, in which solder or brazing material is passed through perforations in one plate for connection with the other plate.

In this case, if the plate provided with the perforations is made of non-solderable material, the solder will form a drop shaped rivet head which can hold the plates together. However, it has been found that relatively much solder is required to obtain a high strength of such a compound, which is due to the fact that the rivet head, if not made quite large, tends to slip through the perforation when it consists of a single hole, if a pull in one plate is perpendicular to the other plate, while the rivet head, when several holes are present, must cover them all. Therefore, this method has essentially only applied in cases where the connection is to withstand only forces which are substantially parallel to the plates.

The object of the present invention is to provide a riveting compound of the type mentioned initially, which is suitable for mass production, with a relatively small amount of solder a sufficiently strong connection can be obtained between blanks of thin sheet material.

This is achieved by a rivet joint of the type mentioned according to the invention, characterized in that the rivet head formed by the solder is designed such that its extension in the direction perpendicular to the can lid and the plate piece is less than the extension of the natural droplet shape in this direction, while the extension of the rivet head in the direction parallel to the can lid and the plate piece is greater than the extension of the natural droplet shape in this direction. Hereby the rivet head can be caused to overlap the perforation edge so much that the strength of the rivet joint is solely determined by the strength of the rivet shaft, eliminating the risk of the rivet head passing through the perforation without the use of a large amount of solder.

An embodiment of the rivet joint according to the invention is characterized in that the rivet head has a generally planar top side. This provides assurance that the rivet head does not inadvertently grasp objects which are passed close to the rivet connection, possibly a complete recess of the rivet head in the plate piece can be obtained.

The invention further relates to a method of making a rivet compound of the above-mentioned type by perforating a sheet with non-solderable surface and pouring solder through the perforation so that the solder is attached to a solderable surface of a can lid and further forms a rivet head at it. away from the can lid facing side of the plate. According to the invention, this method is characterized in that the rivet head formed by the solder, before being fully solidified, is formed such that its extension in the direction perpendicular to the can lid and the plate piece is reduced relative to the extension of the natural droplet shape in this direction, while the extension of the rivet head in parallel with the can lid and the plate piece simultaneously increases. This makes it possible to use a relatively small amount of solder to produce a relatively strong rivet compound of the kind mentioned above.

An embodiment of the method according to the invention is characterized in that the forming of the rivet head takes place during the simultaneous cooling of the solder, e.g. using a cooling piston. This allows the forming operation to be carried out very quickly, which is of great importance for the utility of the method in mass production.

The underside of the rivet head can be formed by forming rounded edges around the perforation, whereby a certain degree of control of the solder is obtained, so that while it is liquid, it is retained outside the perforation, which is of great importance if the can lid and the plate immediately after placing the liquid brazing material in the perforation, it must be passed on to enable a rivet connection to be made between a subsequent can lid and an associated plate.

The rivet head underside can also be formed by forming a bowl-shaped recess around the perforation, thereby providing even more powerful control of the liquid solder, allowing relatively strong acceleration and deceleration of the can lid and the associated sheet piece before the solder is solidified, and at the same time the plate piece is made to lie at some distance from the can lid, which is convenient in some cases, e.g. in which it is a plate used as a pull tab for a can, thereby making it easier to grip the pull tab.

The rivet connection and method according to the invention are explained in more detail below with reference to the drawing, in which FIG. 1 shows a cross section through an embodiment of the rivet joint according to the invention; FIG. 2 is a cross-section through another embodiment of the rivet joint according to the invention; and FIG. 3 is a cross-section through yet another embodiment of the rivet joint according to the invention.

In FIG. 1 shows two items 1 'and 2' of thin sheet material, e.g. a can lid and a plate-shaped pull tab, the blanks of which one 1 'consists of a solderable material, while the other 21 comprises at least at the surface facing away from the blank 11 a non-solderable material.

In the blank 2 'a through hole 3' is formed, through which the precursor rivet 4 'consisting of a solder which is soldered to the blank 1' is formed.

Between blanks 1 'and 2', additional blanks may be provided when each of them is provided with a hole corresponding to the hole 3 'and flushing thereof, but such additional blanks are not shown in the drawing, since only the outer blanks, viz. partly the item in capelin connects Ise with nineteen 4 "and partly the item against which the rivet head rests is of importance to the collection.

The FIG. 1 is prepared by placing the blank 2 'with at least one non-solderable surface and a pre-formed through hole 3' on the blank 1 'of solderable material such that the surface facing away from the blank 1' of the blank 2 'is the non-solderable surface, after which liquid solder is caused to drip into the hole in the blank 21 so that this solder is soldered to the blank by soldering 11, since the blank 2' in the area around the hole 3 'is not solderable in the at least not at the side facing away from the blank 1 ', the liquid solder will form a drop next to the hole 3', which drop due to the surface tension of the solder will be generally spherical. Cooling is then carried out, whereby the solder solidifies to form the rivet 4 '· joining the blanks 1' and 2 '.

In this embodiment, the rim of the hole 3 'is bent. towards the blank 1 'so that the hollow rim at the away side of the blank 1' of the blank 2 'is rounded. Hereby, a certain assurance is obtained that during the manufacture of the rivet joint the drop of solder remains outside the hole 3 'in the blank 2', which allows the items to be moved before the solder which is to constitute the rivet 4 'is solidified. Such movement of the blanks during the manufacture of the rivet joint can in many cases be of crucial importance in achieving an economically satisfactory joining process, the blanks to be joined can be advanced in rapid succession to a position where solder application is carried out without each workpiece pair remains in this position until the applied solder is solidified.

6 146679 at some distance from the workpiece 1 ", which is convenient when the combined solder and rivet assembly is used for attaching a pull tab to a can lid, the pull tab being easier to grasp when it is at some distance from the can lid than when close to this.

In FIG. 2, another embodiment of the rivet compound according to the invention is shown. A workpiece 1 "of solderable material is joined to a workpiece 2" containing a hole 3 "by means of a rivet 4" of solder which is soldered to the workpiece 1 "and which has a rivet-head-like end next to the hole 3 ", the blank 2" having a non-soldered surface.

In the blank 2 "a bowl-shaped recess is formed which is concentric with the hole 3", the blank 2 "being pressed against the blank 1". This provides a better holding of the droplet of liquid solder outside the hole 3 "than is the case in the embodiment shown in Figure 1. At the same time, the rivet head is recessed to some extent in the recess around the hole 3", thereby reducing the risk that the "rivet head "clinging to objects passing the collection is diminished. This may be important when the assembly is used for attaching a pull tab to a can lid, in that when stacking such cans it is possible that a can bottom scrapes over a can lid underneath, whereby the edge of the can bottom can possibly grip. in a rivet head projecting upwards from the can lid, which at worst may cause the rivet head to be torn off so that the assembly is destroyed or that the pull tab on the can lid is pulled so strongly that this can lid is opened.

FIG. 3 shows a further development of this embodiment of the rivet joint, wherein the rivet head during the solder cooling, e.g. by means of a cooling plunger, is pressed into the bowl-shaped recess so that the rivet 4 "" does not protrude appreciably above the top surface of the blank 2 ". Thus, by forming the "rivet head" during solidification, an optimal strength of the joint can be obtained, which can be utilized to achieve a solder saving. The aforementioned shaping of the rivet head may also be used in connection with the other embodiments of the assembly mentioned above.

A combined solder and rivet joint according to the invention is particularly suitable for joining two blanks, one of which is solderable while the other is non-solderable, but it can also be used, although the blanks do not exhibit these properties, merely a surface of one blank can be made solderable, and a surface of the other blank can be made solderable. This can be done, for example. is done by applying a coating to the blanks. For two solderable items, the coating on the item to be made non-solderable, e.g. consist of a lacquer layer, a silicone coating or a chromium layer, optionally such coating which should nevertheless be applied for other reasons.