The present invention relates to a method and means for making cross-running
steps on a pre-profiled plate, where the plate is guided in two pairs of tools
and where one of the tool pairs is moved in relation to the other one essentially
in a direction perpendicular to the plate a distance corresponding to the height
of the step, whereupon the tool pairs are opened and the plate is fed forward a
predetermined distance and the forming sequence is repeated.
There are a plurality of patent specifications that describe the
manufacture of roof tile patterned plates. SE-A-416069 describes a stretching method.
SE-A-447146 describes a bending method. SE-A-453003 describes a drawing method
wherein there is a fixed holding in one of the tool pairs so that all sliding
occurs in the other tool pair. Also US-A-4250728 describes a method wherein there
is a fixed holding in one of the tool pairs.
All of the above mentioned specifications disclose a roof tile imitation
with a symmetrical, just about sinus formed wave shape having a greatest angle
to the development plane of the plate of about 45°. Actual roof tiles normally
have a non-symmetric wave shape where one flank of a wave has an angle of e.g.
30° whereas the other flank has an angle of e.g. 60°. Making cross-running steps
on a pre-profiled plate becomes increasingly difficult with a steeper flank angle
of the profile. On one hand the tendency to form folds in the step increases, and
on the other hand the stress on the coating of the plate will increase. Particularly
sensitive is a thick plastic coating, a so called PVC-plastisol.
The invention has for its object to provide an improved and lenient
method for making cross-running, smooth plaits on a pre-profiled plate and a device
which makes cross-running, smooth plaits in a manner which is lenient to the pre-profiled
and normally plastic coated or lacquered plate. A specific object of the invention
is to permit making cross-running plaits on a pre-profiled plate having a steep
flank angle and/or a thick plastic coating, e.g. a so called plastisol coating.
These objects are met by the characterizing features as set forth
in the claims.
The invention will be described with reference had to the accompanying
figures which fragmentary illustrate one embodiment of the invention.
- Fig. 1 is a fragmentary longitudinal section through the tools of the device
according to the invention;
- Fig. 2 is a cross section, seen as indicated by the arrows 2-2 in fig. 1, but
showing some more details than fig. 1;
- Fig. 3 corresponds to fig. 1 but shows the tools in other mutual positions;
- Fig. 4 and 5 correspond to fig. 1 but shows the tools in further other mutual
Fig. 1 shows a first pair of tools having tools 11, 12 and a second
pair of tools having tools 13, 14. Fig. 2 shows the tool pair 13, 14 in a cross
view, enlarged and in more details than fig. 1 which is very diagrammatical. The
tools 13 and 14 comprise holders 30, 31 which have replaceable three part inserts
32, 33 adapted to the cross-sectional shape of the pre-profiled plate 15 which
is introduced between the tools. The upper tool 14 is vertically movable in relation
to the lower tool 13 by means of two motors in the shape of hydraulic cylinders
34, 35. Between the tool pairs 13, 14 there is formed a slot for the plate 15,
and this slot is defined by interchangeable stops. The tool pair 13, 14 is guided
mechanically as one unit, so it may perform a vertical movement which is brought
about by means of two motors in the shape of hydraulic cylinders 38, 39 mounted
in the machine frame, not shown.
In principle, the tool pair 11, 12 is designed in the same manner
as the tool pair 13, 14 and defines, similarly, a slot for the plate 15 in such
a manner that the plate does not become squeezed when the tool pair is closed.
The tool 11 of the tool pair 11, 12 is vertically fixed but the tool
pair 11, 12 is horizontally movable as one unit a few millimetres between its normal
position, shown in fig. 1 and 3, and a clamping position, shown in fig. 4, by means
of a motor in the shape of a hydraulic cylinder 40. The tool 12 is vertically
movable relative to the tool 11 between an operational position shown in fig. 1
and fig. 3, in which the slot between the tools 11, 12 for the pre-profiled plate
15 is greater than the thickness of the plate, e.g. 110-200 % of the plate thickness,
and an open position, shown in fig. 5. The tool 14 of the tool pair 13, 14 is similarly
vertically movable between an operative position relative to the tool 13, shown
in fig. 1 and fig. 3, in which the slot between the tools 13, 14 is of the same
size as the one between the tools 11, 12, and an open position, shown in fig.
4. As shown in fig. 1 the slot 19 between the two tool pairs similarly is greater
than the thickness of the plate, e.g. at least 110%, preferably at least 150% of
the plate thickness, but preferably less than 500% of the plate thickness. In
a preferred embodiment it is 150-250% of the plate thickness. A typical plate thickness
is 0,1-1 mm. It should be noted that the figures not are true as to the scale.
Fig. 1 and 3-4 are fragmentary and diagrammatical, and they do not
show the feeding device of the machine to feed the plate stepwise. However, such
a feeding device is trivial. The only thing which is shown, beyond the tool pairs
11, 12 and 13, 14 and the hydraulic cylinders 39, 40 is a stop 16. However, the
feeding device is shown in fig. 2. It comprises two slide blocks 50, 51 which slide
on guides 52, 53 in the machine frame. The slide blocks 50, 51 have jaws 54, 55
which by means of hydraulic cylinders 56, 57 may grip the edges of the plate to
feed the plate one step forward as the slide blocks 50, 51 are then moved by means
of feeding cylinders, not shown.
However, the figures 1 and 2-4 are sufficient to explain one sequence
for making a cross-running step on the plate 15 which has been pre-profiled by
roll forming, and such a sequence will now be disclosed. From the start position
in fig. 1, with the plate fed forward since the step 22 was formed, the tool pair
12, 13 is moved vertically downwardly, i.e. transversely to the main plane of the
plate, lying horizontally. As the plate is not fixed anywhere, and not even clamped,
the plate will be drawn into the two pairs of tools, and, when the major part of
the new step 23 has been formed, the earlier formed step 22 will engage with the
stop 16, as is shown in fig. 3, and the drawing into the tool pair 13, 14 stops,
so that the last portion of the forming takes place during drawing in into only
the tool pair 11, 12. By the plaiting a wrinkling may take place particularly
where the flanks are steep, and such irregularities are then flattened out when
the tool pair 13, 14 has reached its end position, as the hydralic cylinder 40
presses the tool 11 to clamp the step between the tools 11 and 14, as is shown
in fig. 4. Thus, the clamping takes place between the two opposing surfaces 24
and 25 of the tools 11 and 14. It is the tools 11 and 14 that are directly shaping
whereas the tools 12 and 13 are guiding.
As the shaping of the step 23 has now been completed the two tool
pairs are opened, i.e. the tools 12 and 14 are raised to their positions as shown
in fig. 5, and the plate 15 is fed forwardly a predtermined distance. The tool
pairs are then closed and the sequence is completed, and the position in fig.
1 has been resumed.
As the front side and the back side of the plate often are provided
with different coatings it is not possible to easily calculate the sliding within
the two tool pairs, but one has instead to adapt oneself to the actual sliding.
Thereby one starts by making a plurality of cross-running plaits without use of
the stop 16 and measuring the drawing in into the tool pair 13, 14. If one finds
that the drawing lies in the interval 11-12 mm, for instance, the feeding is preferably
adapted in such a manner that the initial distance between an existing step and
the stop is slightly less, e.g. 10 mm. Then, the stop 16 will bring about that
the last drawing in of 1-2 mm always takes place in the tool pair 11, 12. However,
the major portion of the step is formed while the plate may slide freely within
the tool pairs. Thus, a very accurate "roof tile length" is achieved, i.e. the
distance between the steps 22, 23, despite the fact that the shaping, which may
be characterized as a deep drawing without clamping force, is very lenient.
Thus, if the height of the step is 25 mm, the stop 16 is engaged
at first when more than 90% of the step has been formed. It is desirable that as
much as possible of the step has been formed as the stop is engaged, and the above
example is realistic. However, an improvement as compared to prior art technique
is achieved if at least half of the step has been formed before the stop 16 is
engaged. A clear improvement is achieved if at least 60% of the step has been
formed before the stop 16 is engaged, and a further improvement for 75%. However,
for very difficult combinations of shape and material, e.g. pre-profiled plate
having steep flanks and a plastisol coating, it will be required for at least
90% of the step to be formed with free drawing in of the plate into the two tool
pairs before the stop 16 is engaged, to ensure a satisfying result.
The formed steps 22, 23 may be flat or may they be crowned inversely
to the pre-profiling, as is shown in SE-A-447146 and US-A-4250728, or may they
have any shape there-between. In figures 1 and 3-5 flat steps 22, 23 are shown
and the plate is shown in its section only. The rearward pre-profiling of the
plate is not shown in as much as that would only tend to make the figures more
difficult to understand. The figures 1 and 3-5 may also be considered to show
the tool pairs with tool edges that are ondulating rather than straight, as seen
from above, to make inversely ondulated steps, but in this case only a section
of the tool pairs is shown whereas the rearmost portions of the tool pairs are
The invention may be varied within the scope of the claims. As an
example of a modified embodiment it should be mentioned that the tool pair 11 may
be vertically fixed, whereas instead the vertical movement of the tool pair 13,
141 may end with an oblique movement inwardly (e.g. with an angle of 45° - 60°
to the horizontal) that results in a clamping of the step.