Rotary ironing machine

In a rotary ironing machine for applying treatments such as ironing, embossing and the like to sheet materials such as leather, cardboard and the like, the cylindrical ironing surface is provided on a thin-walled hollow cylinder, the sheet material is fed by a conveyor belt between said cylinder and an external pressure roller, a counter-pressure roller being provided within the cylinder. Radiation heating means are provided for the ironing surface, externally or preferably internally of the hollow cylinder. Said cylinder is supported by external or internal guide rollers which, together with the heating arrangement, are supported by a carrier which is disposed within the cylinder and is supported at only one end thereof. Other details are disclosed, including a retaining arrangement, for retaining and spreading the sheet material and stripping arrangements with oscillating stripper fingers.

The present invention relates to machines for applying treatments such as 
ironing, embossing, and the like for sheet materials such as leather. In 
particular, it relates to such machines of the general type known as 
cylinder machines, having a cylindrical ironing surface, embossed where 
appropriate, a pressure cylinder or roller, a conveyor belt which guides 
the leather between the ironing surface and the pressure cylinder, and 
heating means for heating the ironing surface. 
Ironing of leather calls for the application of high pressures at elevated 
temperature with the consequence that the ironing surfaces must not only 
have a high-quality surface finish but must also meet increased 
requirements in terms of thermal stability and mechanical strength. 
Satisfying these requirements does not present any special difficulties in 
machines with flat ironing surfaces (for example, as in the British patent 
specification No. 1,346,649) since flat pressure platens and mating or 
counter-pressure platens, of which at least one is heated, can be provided 
in such a machine. However, ironing machines of this kind do not operate 
continuously, although an attempt has already been made to achieve 
longitudinal feed by imparting vibratory motion to one of the platens. 
However, this is not successful in practice. 
Cylinder machines, of the type mentioned above, are known for continuous 
operation (U.S. Pat. No. 3,587,258). In these machines the leather, laid 
on an endless conveyor belt, is guided between an ironing cylinder and two 
outer pressure rollers and there subjected to elevated temperature and 
high pressure. The ironing cylinder is therefore directly heated from the 
interior by a fluid and the pressure rollers are braced by means of 
bracing jacks to the shaft of the ironing cylinder in order to produce the 
ironing pressure. The shaft of the ironing cylinder is supported on only 
one side. 
In these ironing machines it is important to be able to adapt the 
temperature rapidly to the leather that is being processed or to the 
desired embossing effect, i.e. the heat must be supplied rapidly and it 
must be rapidly dissipated so that another temperature can be set up. When 
such an ironing machine is also used for embossing, it is important to 
find an ironing surface construction which, on the one hand, can be 
rapidly exchanged for ironing surfaces with other embossings and, on the 
other hand, is not too costly. 
In the known machine (U.S. Pat. No. 3,587,258), this problem is supposed to 
be solved by making the driven ironing cylinder comprise an exchangeable 
cylinder barrel or shell, the outside of which has the ironing or 
embossing surface and the inside of which is provided with the entire 
heating device. This cylinder barrel is clamped, by means of wedge 
surfaces, to two end flanges of the cylinder. The barrel can be removed 
when the wedges are slackened. To this end, it is also necessary to 
slacken the bracing elements between the pressure cylinders and the shaft 
of the ironing cylinder so that the cylinder barrel with the integrated 
heating device can be withdrawn from the end flanges and can be replaced 
with a new cylinder barrel and heating device. 
This construction is very complex because precise centering of the cylinder 
barrel on the end flanges encounters some difficulties, more particularly 
since the construction of the end flanges themselves must be 
correspondingly complex. The cylinder barrels with the heating device must 
be constructed in heavy and solid form so that they can withstand the 
ironing pressure. On the other hand, each individual ironing or embossing 
cylinder must be equipped with its own heating device. This greatly 
increases the cost of the machine. 
It is an object of the invention to provide a construction which, on the 
one hand, enables the temperature to be changed in the shortest possible 
time and, on the other hand, permits simple installation and removal of 
the ironing surface. Furthermore, it is desirable to avoid the formation 
of folds in the leather, which frequently occurs in the known ironing 
machines, when the leather is passed into the ironing gap and when it is 
stripped from the ironing surface. 
According to the invention, the ironing surface is defined by a thin-walled 
hollow cylinder and the heating means is constructed as a heating 
arrangement which acts on the said cylinder by radiation from the exterior 
or the interior, and a mating or counter-pressure roller, which rolls upon 
the internal wall of the hollow cylinder, is disposed therein and guides 
together with a pressure roller the hollow cylinder, the feed belt and the 
leather roller in the roll gap between the pressure roller and the counter 
pressure roller. 
Accordingly, the ironing surface is constructed as a simple thin-walled 
hollow cylinder the sole purpose of which is to provide the smooth or 
embossed surface required for ironing or embossing. The ironing pressure 
or embossing pressure on the other hand is produced exclusively by the 
pressure roller and the counter pressure roller between which the hollow 
cylinder is guided and by means of which it is set into rotation. The 
ironing cylinder itself is hardly exposed to any stresses, more 
particularly it is not exposed to any bending stresses which are absorbed 
exclusively by the two smaller rollers and can be readily controlled 
thereby. The other advantage resides in the comparatively low thermal 
capacity of the hollow cylinder, due to its thin walls, so that the 
installed heating power need only be low. Furthermore, the said hollow 
cylinder rapidly transfers its heat to the leather. Because of its low 
mass, the hollow cylinder also cools rapidly. The accuracy of temperature 
control is assisted by the low mass. Finally, the said hollow cylinder can 
be readily exchanged. Since the hollow cylinder is merely a simple 
cylindrical sheet metal plate, it is possible to change from ironing to 
embossing or to change between different embossing effects with low costs 
even in the case of small batches. The hollow cylinder of large diameter 
and the feed belt ensure that the leather is spread in the course of the 
feed motion, i.e. that it run onto the cylinder without being folded. 
According to one advantageous embodiment of the invention, the interior 
and/or exterior of the hollow cylinder is guided centrally with respect to 
its axis by means of stationary guide rollers or the like. The hollow 
cylinder therefore rotates like an ironing cylinder but without having its 
heavy construction or a drive. 
The heating device is advantageously constructed as a radiating heating 
device and is disposed on an arc at a distance from the internal wall of 
the hollow cylinder. Generally, this arrangement is located approximately 
diametrically opposite to the two pressure rollers within but preferably 
in front of the feed region in which the leather enters the gap between 
the hollow cylinder and the feed belt. Prior to reaching the pressure 
rollers, the leather is therefore heated and raised to the desired 
temperature since the heated section of the hollow cylinder travels with 
the leather. Compared with previously used heating systems the radiating 
heating system offers the advantage of reaching temperature which are 
higher than those obtained with oil as thermal medium, while nevertheless 
permitting rapid cooling. 
In an ironing machine with the construction as described hereinbefore in 
which the skin is guided through cylinders or similar processing tools and 
is therefore substantially subjected only to one pressure, it is necessary 
for the skin to be spread and tensioned manually on the feeder belt which 
supplies the skin. Spreading and tensioning of the skin must be performed 
with great care because any fold or bubble formed thereby is pressed into 
the leather by the pressure of the processing tools and cannot 
subsequently be removed. Such a skin is substantially useless or only the 
flawless parts thereof can be used. 
Folds, more particularly in the outer region of the skin, can hardly be 
avoided even if the skin has been carefully spread. This fault is due not 
only to the irregular contour of the entire skin but also to its varying 
mass distribution. The relative velocity between the ironing cylinder and 
the skin is constant over the entire length within the processing zone. 
Due to the larger amount of material in the outer region of the skin, it 
accumulates in this region and forms folds after entering in the feed 
region of the processing tools, but the occurrence of such folds cannot be 
discovered from the outside and cannot be prevented. 
To prevent such folds being formed and to obviate the need for manual 
spreading, the invention proposes a retaining roller disposed directly in 
front of a roller around which the feed belt passes at the feed station at 
which the skins are fed to the machine, said retaining roller extends at 
least over the middle region of the roller which reverses the feeder belt. 
The leading portion of the skin is laid on the feeder belt at the feed 
station and the trailing portion of the skin hangs downwardly over the 
retaining roller. If the skin then enters the processing gap the operator 
places his hand firmly on the skin in the region of the brake cylinder 
with the result that the middle region of the skin is held back with 
respect to the outer regions and is thus stretched. By selecting the 
contact pressure the operator is able to adapt the retaining action on the 
middle region of the skin to the appropriate conditions. Advantageously, 
the retaining roller has a relatively small diameter, for example 50 mm, 
so that it can be easily gripped by the operator. Practical tests have 
shown that after the preceding conventional spreading of the skin the 
folds which are then still formed do not occur in the outer regions of the 
skin. 
According to another feature of the invention, one further roller extending 
outwardly from the retaining roller is situated on each side of it. This 
construction enables the operator to retain or stretch the skin optionally 
in different regions. 
In the preferred embodiment of this feature, the two side rollers extend 
from the retaining roller at a downward angle to the outside. This angle 
of inclination causes the outer region of the skin to hand downwards. The 
entrainment of the side rollers, their angle of inclination and the 
friction between them and the skin feeds the skin outwardly and spreads 
it. This dispenses with the previously necessary manual spreading of the 
skin on the feeder belt and manual work as well as any risk of accident 
associated therewith is minimized. 
The retaining roller and the side rollers can be supported in a common 
frame. To this end, the retaining roller and the side rollers are loosely 
supported on different shaft angularly related in the region of the side 
rollers and supported on the frame between the said rollers. 
According to another embodiment of the invention, the retaining roller can 
be divided into two or more loosely rotatably supported roller sections, 
to enable specific regions to be optionally decelerated within the middle 
region of the skin. 
A frame of this kind with the retaining roller and the side rollers can 
also be attached to all other leather processing machines with rotating 
processing tools, for example machines for stetching or abrading of 
leather. 
The heat required for ironing causes the leather to stick on the ironing 
cylinder, more particularly in the case of patent leather or dyed leather. 
Strippers in the form of stripper surfaces which extend over the entire 
processing width and bear by means of a sharp edge upon the ironing 
cylinder are known for detaching the ironed leather from the ironing 
cylinder. 
Practical experience has shown that such strippers are unable to reliably 
detach fine, i.e. thin leather, from the ironing cylinder. Instead, the 
leather is built up on the stripper, forms folds and is creased. 
According to the invention, this is avoided in that the stripper comprises 
a plurality of stripper fingers which are distributed over the processing 
width and are oscillatingly driven parallel to the axis of the ironing 
cylinder. Practical experience has shown that even extremely thin leather 
can be "peeled off" the ironing cylinder without forming folds. The 
oscillating motion in conjunction with the rotating motion of the ironing 
cylinder results in a relative peeling motion at an angle across the 
ironing cylinder, this motion being evidently responsible for the fact 
that even thin leather does not form any folds on the stripper. 
Advantageously, the stripper fingers are mounted on a common rail which 
extends over the processing length width, said rail being oscillatingly 
driven. The stripper fingers can be mounted on leaf springs which in turn 
are mounted on the rail. A simple eccentric device which drives the rail 
in a suitable manner is used for generating the oscillating motion.

The ironing machine substantially comprises a pressure roller 2, a counter 
pressure roller 3, a hollow cylinder 4 which forms the ironing surface, a 
heating device 5 and an endless feed belt 6. These parts are arranged on a 
common machine frame 1. 
The hollow cylinder 4 consists of thin sheet metal 7 functions as the 
ironing surface its external surface being therefore polished or, in the 
case of an embossing cylinder, provided with an embossing pattern. Rings 
are provided at least of the endfaces of the cylinder 4, for stiffening 
the ironing surface. A stationary tubular carrier 9 is disposed within the 
hollow cylinder 4 along its axis and supports on its two ends a spider 10 
with guide rollers 11. The rollers retain the hollow cylinder in a 
position which is central with respect to its axis. The tubular carrier is 
fixed to the frame 1 on only one endface of the hollow cylinder 4. 
The counter pressure roller 3, already indicated, is situated in the 
interior of the hollow cylinder 4 and rolls upon the internal wall 
thereof. Together with the externally disposed pressure roller 2 it forms 
the actual ironing zone through which the hollow cylinder 4 is guided. The 
pressure roller 2 is urged towards the counter pressure roller 3 by 
hydraulic or pneumatic jacks 12 to provide the desired ironing pressure, 
for which purpose the bearing pedestal 13 of the pressure roller 2 is 
slidingly seated upon the machine frame 1. The pedestal 14 of the counter 
pressure roller 3 is fixed to the carrier 9 or to the spiders 10, 
respectively. The yoke for the jacks 12, the pullong bars (unnumbered), 
and the pedestal 13 are joined together as one piece and are movable by 
means of the pulley bars sliding in corresponding holes in the pedestal 
14. The required restoring force is produced by a spring 15 which is 
inserted between the two bearing pedestals 13 and 14. 
The pressure roller 2 also functions as a reversing pulley on the delivery 
side for the endless web-shaped feeder belt 6 which is also guided over a 
reversing pulley 16 on the feed side and over a drive roller 17. The said 
feed belt 6 surrounds the hollow cylinder 4 approximately in the region of 
its right-hand bottom quadrant and is guided through the ironing zone 
formed between the pressure roller 2 and the counter pressure roller 3. A 
sheet of material such as leather 18, situated on the feed belt 6, first 
passes into the zone of contact described above. The appropriate section 
of the hollow cylinder 4 has the desired high temperature which is 
produced in the preceding sector by radiant heating means 5. The leather 
is therefore first heated in the zone of contact before reaching the 
ironing zone. The heating device extends axially through the entire 
interior space of the hollow cylinder 4 and can be mounted, for example, 
on the endface discs 19 of the tubular carrier 9. 
The hollow cylinder 4 (FIG. 1) is covered, at least on its top, by a hood 
20 which can be swung open about a bearing 21. During the ironing 
operation, the hood is closed to enable the heat to be built up,. The hood 
20 can then be opened for cooling purposes or for lowering the treatment 
temperature. A sheet metal plate 23 which on the one hand serves as a 
guard and on the other hand extends close to the hollow cylinder 4 is 
situated in the inlet region 22 of the feed belt 6 so that air convection 
between the housing 24 or the hood 20 and the hollow cylinder is almost 
eliminated. The said plate 23 can also be swung open for cooling the 
hollow cylinder by pivoting around the bearing 21 clockwise. 
The leather which leaves the ironing machine at the pressure roller 2 (FIG. 
1) can be either removed at that place or can be transferred to another 
conveyor. Instead, the leather can also be returned to the feed side to 
which end a return belt 27 is included in the illustrated embodiment. The 
return belt incorporates a pulley 28 in the back of the machine, a turning 
pulley 29 and a delivery pulley 30 which is situated near the feed side of 
the feed belt. The upper stringer -- the feed stringer 31 -- of the said 
return belt 27 is in contact with the return stringer 32 of the feed belt 
6, at least as far as the turning pulley 17. It then extends at a more 
shallow level than the return stringer of the feed belt 6. The leather 
which emerges from the ironing zone is introduced by a guide plate 33 into 
the gap between the presure roller 2 and the reversing pulley 28 and, due 
to friction between the return stringer 32 of the feed belt 6 and the feed 
stringer 31 of the return belt 7, it is guided downwardly as far as the 
drive pulley 17 and from there is conveyed only by the feed stringer 31 to 
the reversing pulley 30 where the leather can be removed by the operator 
who feeds the leather. 
The ironing machine shown in FIG. 2 also comprises an ironing rollers 4, 
two pressure cylinders 2, 3, a feed belt 6 and two turning pulleys 16 and 
34. A heating system 5 and support rollers 11 are also arranged within the 
ironing cylinder 4. The entire skin 18 is laid on the feed belt 6 with the 
leading section in the region of the feed place 25 and is guided between 
the ironing roller 4 and the pressure roller 2 illustrated on the 
left-hand side of the drawing. 
FIG. 3 shows the skin 18 diagrammatically in plan view. The skin is fed in 
the direction of its longitudinal extent so that the tail part 35 and the 
rear leg parts 36 enter the processing gap first. 
As can be seen by reference to FIG. 2, the return stringer 32 of the 
conveyor belt 6 is guided from below around the turning pulley 16 in the 
region of the feed station 25 and the leading stringer leaves the turning 
pulley in the approximately horizontal or slightly falling direction. A 
retaining roller 26 is arranged directly in front of the turning pulley 
16, i.e. at a slight distance thereform. As shown in FIG. 4, the retaining 
roller 26 is supported on the uprights 37 of a frame 38. In the 
illustrated embodiment, the retaining roller 26 extends only over the 
middle region of the turning pulley 16. Side rollers 39, inclined at an 
outwardly downward angle, are arranged between the retaining roller 26 and 
the outer ends of the turning pulley 16. The inner ends of the said side 
rollers are supported on the uprights 37 and the outer ends are supported 
on the uprights 40 of the frame. 
The retaining roller 26 and the side rollers 39 are situated on different 
shaft sections 41 which are angularly related in the region of the 
uprights 37 in accordance with the angle of downward inclination of the 
side rollers 39. The retaining roller 26 and the side rollers 39 are 
freely rotatable on the shaft 41 by means of radial bearings 42. As 
indicated in FIG. 4, the retaining roller 26 can also be subdivided into 
several sections, for example three sections 42, 43 and 44, each section 
in turn being loosely supported on the middle shaft section 41. 
FIG. 2 indicates a stripper 45 behind the ironing gap, i.e. behind the 
ironing cylinder 4 and the outer pressure roller 2, and it should be noted 
that the said stripper is not identical with the guide plate 33 in the 
embodiment of FIG. 1. As may be seen by reference to FIGS. 6 and 7, the 
stripper 45 comprises several stripper 15 fingers 46 which extend over the 
entire processing length width of the machine. In the illustrated 
embodiment, the stripper fingers 46 are situated on leaf springs 47 which 
in turn are mounted on a rail 48. The stripper fingers 46 consists of a 
material, for example PTFE, which is on the one hand sufficiently soft so 
as not to damage the highly polished ironing cylinder but on the other 
hand is sufficiently thermally stable. 
The rail 48 is mounted on a hollow section 49. A motor 50 whose shaft 51 
engages in the hollow section 49 and is provided at the end with an 
eccentric device 52, is situated on the hood 20 which is illustrated in 
FIG. 7 but is omitted from FIG. 2 in the interests of clarity. The 
eccentric device 52 is situated with slight clearance between two webs 53 
which are mounted on the hollow section 49. The hollow section 49 is 
supported on a sliding member 54 which is secured to the hood 20 by means 
of an arm 55.