Method of manufacturing solid wheel rims

A method of manufacturing a solid wheel rim having a wheel-rim flange at one end of a wheel rim base and a spring-ring groove at an opposite end of the base, from a rolled and a longitudinally welded sheet-metal ring of a predetermined inner diameter having a reduced wall thickness over at least a part of its length, includes the contraction of a portion of the ring to produce an annular groove zone having an inner diameter of a first predetermined size, an enlarged zone having an inner diameter greater than the inner diameter of such predetermined size, and a tapered zone located between the annular groove and enlarged zones, the wall thickness of the ring being reduced during a pressing operation, and the spring-ring groove as well as the wheel-rim flange being formed during a rolling operation.

The invention relates to a method of manufacturing solid wheel rims, for 
example, for trucks or lorries with a wheel flange at one side of the 
wheel rim base and a spring ring groove at the other side, from a rolled 
(rounded) and longitudinally welded sheet metal ring which is shaped to 
the respective section shape and the wall thickness of which is reduced 
over at least part of its length. 
In this case the term "wheel rims" is taken to mean the wheel rim base for 
multiple-part longitudinally or transversely divided wheel-rims comprising 
a wheel flange, tire seat, a wheel-rim bed and if a necessary hook-shaped 
portion. The starting material may also be rings cut from an elongated 
tube. 
In a known method of this kind (German Federal Republic Offenlegungsschrift 
2343247) the spring ring groove is first of all impressed at one end of 
the sheet metal ring, the sheet metal ring is then shaped in determined 
zones from the spring ring groove towards the flange end and then 
stretched to its desired wall thickness and thereafter the other end is 
opened out to form the flange. The stretching takes place therewith 
through two rolling surplusses, the wheel rim base being extended in the 
second surplus. This known method is relatively complicated on the one 
hand having regard to its separate operations or procedures, as the 
extension of the wheel-rim base and the formation of a recess for the 
spring ring have to take place in separate operations, and on the other 
hand is relatively expensive having regard to the tools employed. Also, 
there is not attained at least in the zone of the spring ring groove the 
optimum varying wall thickness which is in conformity with the incident 
loads, as the spring ring groove is formed before the extension is 
effected. Thus, too much unnecessary material is always accumulated. 
Moreover after the known method the outer edging must subsequently be 
calibrated and the radii between the wheel rim base and on the one hand 
the annular groove, and on the other hand the flange, have to be smoothed. 
An object of the present invention is to provide a method of the 
aforementioned type in which there is obtained over the whole profile of 
the wheel rim a varying wall thickness precisely conforming in all points 
and zones to the required cross-section, and which can be conducted simply 
and with cheaper tools. 
In carrying out this objective provision is made according to the invention 
for the rolled (rounded) and longitudinally-welded sheet-metal ring to be 
expanded partially or to different diameters during the rounding by 
variable expanding, or contracting, for the enlarged or contracted zone or 
zones together with the annular groove end and any zones located 
therebetween to be then brought to different wall thicknesses by hydraulic 
pressure or the application of pressure, for the annular groove outer end 
and the flange end to be finally shaped preferably by rolling. The 
expanding or contracting may be effected during the rounding procedure, 
or, by the use of special tools, the rounding may be effected by the 
expanding or contracting operations. 
In this way there is produced a relatively simple method of manufacturing 
for example solid wheel rims, in which, by hydraulically pressing the 
enlarged sheet metal ring at each zone of the later to be formed flange, 
of the wheel-rim base and of the annular groove, precisely these wall 
thickness and that transition between two different wall thickness can be 
achieved which conforms to the later loading in the working condition. 
This effects a saving in material and makes possible an increase in 
strength and rigidity of the wheel-rim surface is specific zones. It is 
possible with this process to stretch those zones at which little material 
is required, and to put or displace this material into those zones at 
which much material is required. 
This can be reproduced with a very high degree of accuracy. The simplicity 
of this procedural step is a result of the possibility of pressing in one 
working operation also the conical transition from the wheel-rim base to 
the flange together with the reduction in wall thickness. A further 
advantage consists in that the likewise necessary rounding of the 
sheet-metal ring after its longitudinal welding is used at the same time 
for the purpose of expanding the ring in such a way that the later 
wheel-rim base and the zone of the later flange receives a greater 
diameter relative to the annular groove, there being formed between the 
cylindrical form of the wheel-rim base and that of the annular groove a 
conical zone which later forms the transition from the annular groove to 
the wheel-rim base. After these two essential procedural steps which make 
possible a wall thickness adaptation to optimum requirements and 
compensation for tolerances in the starting material by the axial 
displacement of the material and hence simple trimming operations and a 
constant contour yield in the critical zones there takes place the 
pressing and rolling operations which with simple tools and simpler types 
of machine achieve an economic improvement in the hydraulic pressure 
profiling. A further advantage consists in that, in the method according 
to the invention, subsequent smoothing in the rounded zones between the 
wheel-rim base and both the annular groove and the flange is not 
necessary, since the smoothing effect is attained on pressing of the 
annular groove and the flange. 
In an embodiment of the present invention the inclined wall zone extending 
between the annular groove and the wheel-rim base is pressed to a cone the 
inner surface of which subtends an angle of 28.degree. with the axis of 
rotation of the ring, which is essential for the centering on mounting the 
wheel-rim on the wheel spider. 
In a further embodiment of the present invention, the wall-thickness 
reduction takes place in a press, while the preforming and final forming 
of the annular groove end and the flange end take place in rolling 
machines, whereby the annular groove end and the flange end can be worked 
simultaneously on a rolling machine in common or alternatively on two such 
machines in two consecutively-occurring working operations. The advantage 
is to be seen in the fact that operating sequences by means of rolling are 
cheaper than those by means of pressing.

In the method according to the invention of manufacturing a solid wheel rim 
11, preferably for trucks or lorries, from a sheet-metal strip 12, the 
latter according to FIGS. 1 to 5 is first cut to a specific length Lo and 
width Bo from sheet material having a thickness So, shaped by rolls into a 
cylindrical ring with a specific inner diameter Do, and provided at a 
height H with a flattening in the area 14 of the abutment; the abutment 
area 14 of the rolled ring 13 is then longitudinally welded and the line 
15 of weld subsequently smoothed. This now closed ring is then again 
rounded, in the embodiment shown in the drawing. The sheet-metal ring 13 
in accordance with FIG. 6 is reamed up and simultaneously rounded by use 
of a special tool in such a way that the zone 16 of the later annular 
groove retains its inner diameter d, substantially equal to inner diameter 
Do of the sheet-metal ring 13, whereas the remaining zone 17, which later 
forms the base of the wheel rim, is reamed up to a larger inner diameter 
d.sub.2, a conically-inclined zone 18 being formed between these two 
coaxial zones 16 and 17. The conical zone 17" for the wheel-rim flange 
follows the zone 17. The expanded sheet-metal ring 13 thereby still has 
over its full axial length the same wall thickness so that the original 
sheet 12 had. The diameters of the regions 16, 17 and 20 may besides, if 
necessary, be exactly calibrated. 
The variation in wall thickness of the sheet-metal ring 13 is now made in 
accordance with FIG. 7 on a first press precisely to the operational and 
strength requirements. This wall thickness varying differently in the 
axial direction, is effected during one working operation starting from 
the zone 16 at the annular groove end. Whereas the zone 16 is made only 
slightly thinner and retains a constant thickness over its length, a 
tapered shape is impressed at the conical zone 18, in such a way that the 
course from the inner side 19 relative to the outer side is initially 
conical and is then concentric in the zone of the external bend 21 between 
the zones 18' and 18", so that in this zone 18" there is a considerable 
accumulation of material. This also yields a reduction in the material 
stress between the zone sections 18' and 18" of the conical Zone 18; 
associated therewith is a stiffening of the surface. The above-described 
surface and wall thickness development is not an absolute necessity. 
Departures from this can be made according to the structural conditions at 
any given time, e.g. when deviation from the stress are necessary. The 
inner surface 19 of the inclined zone 18' pressed into a conical shape in 
thickness, forms an angle .gamma. of 28.degree. with the axis of rotation 
of the wheel rim. The zone section 18" passes internally over into the 
zone 17' and externally by way of a conical surface 22 into the zone 17'. 
The zone section 17' which later forms the base of the wheel rim, receives 
a wall thickness substantially reduced relative to that of the original 
wall thickness and passes by way of a relatively shallow conical surface 
23 into the zone section 17" which has about the original wall thickness 
So and which later forms the wheel flange. The conical surface 23 is 
moreover arranged in such a way that it ends in the zone of the later 
transition to the flange. The zone section 17" may if necessary also be of 
varying wall thickness. The reduction in wall thickness on the entire zone 
17 is brought about by means of hydraulic pressures from the annular 
groove side to the flange side, whereby a precisely determinable wall 
thickness development is possible and whereby the sheet-metal ring 13 is 
stretched to a greater length L.sub.2. 
The sheet-metal ring 13 with the length L.sub.2 now provided with a wholly 
determined wall thickness may now, in so far as necessary, be trimmed at 
its edges 32, 33 so that it has the total axial length L.sub.3 (FIG. 8). 
According to FIG. 9a, in the case of one embodiment, the annular groove 
end, hence the zone 16, and the wheel-rim flange end, hence the zone 17", 
are then simultaneously preformed through rolling, preferably with an 
angle of slope of about 45.degree.. This preforming takes place in a 
rolling machine. Also in a rolling machine the two zones 16 and 17" are 
then converted into their final shape to form the annular groove 26 and 
the flange 27, the wheel-rim receiving its final length L.sub.4 (FIG. 9b). 
It will be understood that the two working operations in accordance with 
FIGS. 9a und 9b can be carried out on the same rolling machine or 
different rolling machines in consecutive working operations. The 
wheel-rim base is formed at the same time between the wheel-rim flange 27 
and the annular groove 26. 
In a modification of the invention the working operations according to 
FIGS. 9a and 9b are combined into one working operation, that is starting 
from FIGS. 7 or 8 the annular groove 26 and the wheel-rim flange 27 are 
simultaneously finally shaped by rolling. The wheel-rim flange end is 
already preformed in the working operation according to FIG. 6 and trimmed 
as represented at 17" in dash-dotted lines starting from this point and 
according to FIG. 7 the alterable wall thickness is produced in the whole 
region by hydraulic pressure, and thereafter, according to FIG. 9b, the 
annular groove 26 and the wheel-rim flange are simultaneously finally 
shaped by rolling. On the other hand the annular groove end 16 is finally 
shaped directly without the intermediate step according to FIG. 9a. 
According to FIG. 10 the diameter of the wheel-rim base 28 may besides then 
be calibrated to its diameter d.sub.3, if this should be necessary. 
Instead of being purely expanded, the ring 13 according to FIG. 8 may be 
partly expanded and partly contracted in such a way that the region 16 of 
what is later to be the annular groove has a diameter smaller than the 
inner diameter of the ring, whereas the diameter of the region 17, 
corresponding to what is later to the wheel-rim base, corresponds to the 
inner diameter of the ring or is greater than it. 
The arrangement may for example also be such that, if actual circumstances 
demand, the base of the finally-shaped wheel-rim may be further deformed 
by an additional rolling or pressing operation, as is shown purely by way 
of example at numberal 40 in FIG. 10. 
Although my invention has been illustrated and described with reference to 
the preferred embodiments thereof, I wish to have it understood that it is 
in no way limited to the details of such embodiments, but is capable of 
numerous modifications within the scope of the appended claims.