NO144916B - PROCEDURE FOR MAKING ALUMINUM WHEELS OF TWO PLANE PLATES - Google Patents

Description

The present 'invention' relates to a method for producing

position of vehicle wheels of the type fitted with air-filled tubes or tubeless tyres.

In particular, the invention applies to wheels made of alloyed aluminum sheets.

Vehicle wheels of the type mentioned here will in the following be referred to simply as wheels and include the rim track, the rim, and the disk that connects the rim and the hub. The main application for such wheels is as car wheels, but other applications are also conceivable, e.g. for' fly.

In what follows, aluminum will be discussed as a material for wheels. With aluminium, different aluminum alloys will be suggested here, unless otherwise specified.

US patent 3 719 980 describes a method for making wheels

of metal sheets. Various designs are shown, all of which have in common that the starting material, two or more round plates, is shaped in a press tool.

The shape of course depends on the desired finished product, but the intermediate stage from pressing always appears with concentric ring-shaped surfaces. The joining of these intermediate products takes place by the surfaces being brought to cover each other and then folded and bent into an S-shaped seam. The seam is formed by the parts of the surfaces that are closest to the center.

The rest of the originally ring-shaped surfaces can be shaped

the desired product.

This process can be used for steel and soft aluminium. The

stronger aluminum alloys required for car wheels will not withstand this process. The method will also require a lot of tools and many work operations.

In US patent 3,117,369, an automobile wheel is patented

of thin plates. The rim and the hub part are manufactured separately and joined both by welding and by subsequent cold deformation in the welded areas.

The cold deformation is carried out so that the deformed parts

of the rim and the hub come into engagement with each other and

strengthens the connection.

The method joins the known production methods for car wheels, where parts are joined together by welding or riveting.

Car wheels are conventionally made of steel. This is due to

the steel's price, strength and well-developed technology, which allows different manufacturing methods to meet set requirements for shape and strength. But with all its good properties, steel has the disadvantage that the wheels become heavy. This influences the unsprung weight of the vehicle. The unsprung weight of the vehicle is of significant importance for the driving characteristics in such a way that these are improved when the weight is reduced. The wheel weight

of course also influences the rotational energy of the wheels,

and finally it must be added that the wheels must conduct away the developed heat from the brakes, and for this aluminum is preferable to steel.

Aluminum is a metal that with its low weight, high strength

and good thermal conductivity should be able to replace steel in wheels. Technology has also been developed for the production of aluminum wheels, both by forging, high-pressure casting and low-pressure casting. By casting, the entire wheel with rim, hub and disc is manufactured in one operation. With appropriate processing and surface treatment, the wheel cap and other trim can be saved, so that you get a product that can compete with the steel wheel in terms of the market.

If the wheel is built from rolled aluminum sheets, the weight can be reduced even more.

There is nothing in the way of building wheels from aluminum sheets using the same methods used for steel wheels. But the special properties of aluminum also provide opportunities for other and more suitable manufacturing methods than

those used for steel wheels.

The applicant has found such a technique, based on his long experience in roll-bond technology and metal printing technology as well as thorough knowledge of the properties of aluminum alloys.

With the new technique, aluminum wheels comprising hub, disc and rim can be produced in one piece with a minimum of tool operations. Within wide limits, the desired external shape can be achieved, as can the required firmness. No particular embodiment is therefore described here.

In general terms, the developed technique will comprise the following steps: 1. First, two flat plates of a suitable aluminum alloy are produced. These aluminum sheets are cleaned and coated with black in a given pattern for the subsequent roll-bonding. 2. In roll-bonding, the plates are rolled against each other so that they are joined except where the black is laid. 3. From this roll-bonded plate, rondelles are produced, i.e. round subjects. The ink is laid in such a pattern that the two original plates are not joined together in a concentric plane along the outer edge of the roundel. Here, the two plates can then be separated from each other and form the rim track in the wheel by subsequent metal pressing. 4. For metal printing - also called spin forming - the roundel is clamped in a press bench. The disc is pressed on a suitable mandrel, which in this case corresponds to the geometry of the rim track.

The connected hub part is also pressed into the desired shape - or it can be shaped using other technology such as deep pressing. 5. The wheels are subjected to final mechanical processing, plugging of holes etc. as well as possible surface processing. 6. The wheels are subjected to the heat treatment that has been prepared for the product in question.

7. Final adjustment and control.

The aluminum alloys must combine high strength and gpd formability. Hardenable alloys exhibit such combinations of properties in that they are very soft in the so-called soft state, hardened or stable soft annealed, while the strength properties can be improved by subsequent hot or cold hardening, depending on the type of alloy. Such alloys are e.g. -AlCu, AlCuMg, AlMgSi, AlZnMg and AlZnMgCu alloys. In particular, the AlMgSi and AlZnMg alloys are well suited, as they also exhibit good corrosion properties, can be surface treated etc.

Several of the hardenable aluminum alloys, and in particular aluminum alloys of the AlMgSi type, have properties that can be used to advantage so that production can be set up as a continuous process as possible. This means that the individual production steps such as roll bonding, curing, forming, curing and possible surface treatment are followed in such a sequence that they are adapted to the condition the material has at any given time. Furthermore, it is believed that one combines production parameters and the final specifications and material requirements optimally, which is of significant importance to achieve an economically profitable production.

Sheets in a suitable aluminum alloy, such as, for example, AlMgSil, are cut to suitable dimensions. One side of the board is degreased, stained, wire brushed and dust and moisture are removed. A print pattern is applied to the plate, e.g. designed as a concentric ellipse, which should represent the area that is not wanted connected.

Another aluminum plate undergoes the same treatment with regard to degreasing, pickling, brushing and removal of moisture and dust. This plate is placed together with the first-mentioned one with the cleaned surfaces facing each other, so that the pressure sealer lies between the plates. Instead of using two plates, you can use a plate of double length. This is folded so that in principle you get the same combination as mentioned above with two plates separated by a suitable print pattern. The plates are brought up to the temperature required to achieve roll bonding for the alloy in question, which means in practice above 35o° C. Heating time and holding time at high temperature should be as short as possible, alternatively an inert furnace atmosphere should be used to avoid too strong oxidation of the surfaces to be roll bonded. This can also be remedied by sealing the gap between the plates. In roll bonding, the plates are rolled down with e.g. 4o% - 7o% thickness reduction in one go and you can then make any adjustments

by later rolling punching to achieve the intended final thickness. It is also possible to use a smaller thickness reduction during hot rolling, provided that the thickness reduction is increased during subsequent cold rolling. The plate thickness before and after rolling is adapted in such a way that the elliptical pressure pattern after finishing rolling takes on a circular shape with an inner diameter corresponding to the diameter of the connected surface.

A roundel with a diameter sufficient to form the entire wheel is punched out. The disc then has a circular connected area surrounded by a concentric ring consisting of two non-connected plates.

The navel is pressed or pressed into the desired shape. The outer and inner rim track is then spin-formed over a suitable mandrel corresponding to the profile of the rim track.

In the description of the main features and in the example, it is said that the rondels are produced by roll bonding. However, it is obvious that the desired result can be achieved with rondels that are produced in another way, e.g. by friction welding, brazing, gluing or riveting. It can also be mentioned that an alternative method to spin forming can be roll forming.

It is mentioned in the description that a continuous manufacturing method would be preferable, not least to make product production more economically profitable. This means e.g. that the rolling together process, the so-called roll bonding, is carried out at such a high temperature and with subsequent cooling adapted in such a way that the material is hardened at the same time.

By a continuous manufacturing method for rims based

on alloys of the AlMgSi type, particular attention must be paid to the fact that the material in the hardened state will cold harden. In order to make use of the temporarily soft state after hardening in the subsequent forming processes without carrying out new soft annealing, it is necessary that the individual forming operations are carried out within a reasonably short time. The requirements for ductility in the forming processes will, depending somewhat on the composition of the alloy, be decisive for how long intermediate storage can be allowed.

The intermediate storage time for alloys of the type AlMgSi should preferably be as short as possible.

By carrying out the individual shaping operations within certain time frames, however, the material will be able to be heat cured immediately after the shaping operations and thereby achieve satisfactory firmness.

It is possible to carry out curing with only a few minutes of heat treatment by using one suitable high temperature and it is also possible to combine this heat treatment with any surface treatment.

In particular, heat treatment such as hardening and tempering will be well suited for a continuous process, provided that a suitable alloy is used.

For example, rims made from alloy AlMgSil can be hardened at 55o° G for 10 minutes and then cured at 215° C for 15 minutes.

The steps in the process are outlined on the attached drawings.

Fig. 1 shows preparation of the plates before rolling

bonding, fig. 2 shows the rondels in a press tool, fig. 3 shows a breakdown of the roundabout for the rim track and fig. 4 shows how the rim takes its final shape.

Fig. 1 shows, in principle, how the plates 1 and 4 posi-

sioned before roll-bonding. On the plate 1 is laid a pattern of ink 2, e.g. graphite, with an elliptical design.

The area 3 within the blackened elliptical ring will, after roll bonding, represent the bonded part of the two plates.

The bonded sheets are punched or cut out of it

composite plate (not shown), whereby a roundel 5 appears, as in fig. 2 is shown placed in a pressing tool consisting of a pad 6, a piston 7 and a pressing ring 8.

In this pressing tool, the disc in the finished wheel gets its

final form.

After pressing, the roundel is placed in a press bench. Here, the tool as shown in fig. 3 of a composite mandrel, consisting of the two parts 9 and lo on each side of the wheel disc 11. During the pressing, the mandrel parts are clamped against each other and lock the wheel disc, so that it. rotates with the mandrel.

A pulley 12 is guided into the unconnected part of the round and splits it, so that these parts 13 can be given the final shape 14 in a subsequent printing or roll forming.

Fig. 4 shows how the tool for this printing or roll forming is assembled. A pulley 11 with geometry corresponding to the outer surface of the composite mandrel 9 and lint gives the rim track 14 its final shape.

Shaping the hub and setting the necessary holes are not shown on these sketches.

Claims (3)

1. Method for the production of a wheel from aluminum for vehicles with rubber rings, compact or pneumatic, where the method comprises the production of cut-to-size aluminum tins, or folded tins and joining the tin pieces in their central area in at least one continuous surface, as well as expanding and shaping of the edges of the bonded sheet of tin thus produced, characterized by the fact that the sheets are bound together by rolling in one or more concentric circular surfaces which are demarcated from each other by surfaces which are coated with a binding-preventing black before rolling. 2. Procedure according to claim 1, characterized in that the tin pieces are made from an Al-Mg-Si alloy and that the finished rim is subjected to solution annealing and cold hardening. 3. Method according to claim 2, characterized in that the heat treatment is combined with a thermal surface treatment.