The present invention relates to casting equipment for production of stairways or staircases in concrete, more particularly an adjustable casting mould production of stairways having various lengths, climbing heights, and number and dimensions of the separate steps in the stairway.

In order to meet the specifications for the stairways for each building construction job the building industry substan¬ tially has been referred to have available a large number of different casting moulds, a situation which obvious is rather cumbersome and expensive, among other things due to the storage space requirements. Frequently it appears that available casting moulds do not present the desired specifications, such that special casting moulds still must be made either in a factory or on the building site.

There is priorily known a number of proposals for adjustable casting moulds for casting stairways in concrete, but known designs have hitherto not been very successful , partly because the constructions have been rather complicated and cumbersome both in construction and use, especially because the possibili¬ ties for adjustments have not proved to be sufficient.

As illustrative for the pri'or art one may refer to German patent No. 35 18 200, German published patent applications No. 21 55 577 and No. 24 07 871, French patent No. 2 332 685 and Swedish patent No. 425 572.

The casting mould in accordance with the present invention presents in spite of a relatively simple construction, very large possibilities for adjustments, such that one by means of the mould may produce stairways and staircases which meet about all different specification requirements, and one can with a couple of manual adjustments in so to speak stepless way adjust the length, climbing height, number of steps and dimensions on the "upsteps" and "insteps" of the stairway.

The casting mould in accordance with the invention is generally characterized by the following features:

- a longitudinal, horizontally extending supporting frame having parallel, longitudinal supporting elements,

- two on the supporting frame displaceably arranged, mutually identical, articulated link arm systems, scissors-like pivotally linked together at the points of overlapping intersection of the arms crossing the longitudinal center line of the system,

- opposing outer points of articulation in each set of arms constituting support for a plurality of step units in such fashion that said step units can undergo pivotal movement in the vertical plane,

- said step units each comprising an "instep" and an "upstep" rigidly interconnected at a right angle,

- each of said step units normally resting by its weight against the adjacent step unit in consecutive fashion,

- means for adjusting the total length of the articulated link arm system thereby simultaneously adjusting the distance between each step unit, and means for adjustment of the angular position of the step units relative to the supporting frame.

With a casting mould in accordance with the invention one can by means of two simple separate adjustments accomplish a stepless adjustment of the length of the stairway and the position of each step unit, respectively. By such adjustments one can also define the number of steps required in the stairway to be built and the climbing height of the stairways as a whole and the climbing height of each "upstep" in the stairway.

Through simple adjustments one can also adjust the lateral width of the "insteps" in the stairway.

The invention shall be further described with reference to the accompanying drawings which in detail illustrate an embodiment for a casting mould in accordance with the invention, and wherein:

Figures 1 and 2 show a lateral view and a plan view, ^" respectively, of a ready mounted casting mould in accordance with the invention.

Figure 3 shows a lateral view seen from the left side of the mould as shown in Figure 1 and in a somewhat enlarged scale.

Figure 4 shows a detail lateral view in a further enlarged

scale and which illustrates the construction of the steps or step unit and the function of same.

Figure 5 shows a fragmentary sectional view along the plane V-V in Figure 1 which, partly in section, illustrates in an enlarged scale, a right half part of the mould and which especially illustrates the side part of the mould and the adjustment of the width of the casting mould and the stairway made thereby,

Figure 6 is showing a fragmentary schematic view along the plane VI-VI in Figure 5.

As appearing from Figures 1,2 asnd 3, the casting mould comprises a support frame 1 consisting of altogether three longitudinal support beams 2,2,2, provided with superimposed transverse beams 3,3,3. On top of the same is further positione altogether four longitudinal channel-shaped beams 4,4,4 which again form basis for two identically arm link systems 6 and 8 , respectively, which are arranged in a symmetrical scissors-like formation and is interlinked in intersection points 9,9, etc. along the center line by means of pivot bolts 10. The bolts 10 are further supported on saddle-like channel brackets 12 which are displaceably mounted between the two central channel beams 4,4. The separate arms in the two arm link systems 6 and 8 are further linked together along both lateral sides by means of pivot bolts 11,11, 13,13, etc. As it best appears from the plane view shown in Figure 2 , the link points at each arm couple are positioned directly opposed each other relative to the longitudinal center axis of the system. Each of the pivot bolts 11,11 etc. forms support for a support sabot 14, the design of which best appears from the detail view shown in Figure 4.

As best appears from Figures l and 4 the course of the stairway is built up by means of step units 16,16, etc. , each of which comprises an "upstep" 18 and an "instep" 20. The upstep 18 includes two or more at a right angle extending support brackets 22,22 at the lower edge of the upstep and is welded to a transverse rod or shaft 24 which is pivotably arranged in transverse diretion and displaceably supported in the sabot 14. The brackets 22 form support for the insteps 20. The insteps

are preferably releasably attached to the brackets 22 by means of screws 26 or the like, enabling the operator to replace the insteps with steps having various widths. In the shown embodiment of the bracket 22 is at the corner zone between the upstep and instep further attached a list 23 which constitutes a section of the instep and is adapted for receipt of the instep via a tongue and groove arrangement or the like.

As shown in Figures 1 and 4 the longitudinal edges 25 on the insteps rest with their weight loosely against the adjacent upstep 18.

The two link arm systems are via the undermost positioned arms looseably and slideably biased against the outer channel beams 4,4. On top of these channel beams 4,4 may, if desired, be positioned longitudinal slide strips 27 as shown in Figure 3.

At the left end of the two arm link systems 6 and 8 the last arm couple 29,31 are pivotally supported on pivot bolts 28,28 which further are supported on collar-like brackets 30 which are displaceably supported laterally on a transverse element 32 attached on the top side of the support frame. Thereby the scissors arms on either side of the central line may move inwardly and outwardly relative to the same during the extension, respectively the contraction of the arm system.

The casting mould includes as mentioned, two possibilities for stepless adjustment, namely firstly a first stepless adjustment of the length of the stairway and thereby the distance between each separate step, by means of the scissors arm system, and secondly a second adjustment of the dimensions of the separate steps.

The length of the scissors arm system is in the shown embodiment adjusted by means of a worm screw 42 which in the right end can be connected to an eletrical motor 44 via a reduction gear or the like. On the worm screw is positioned a threaded bushing 46 which is attached to one of the collar- shaped brackets 12 which form support for one of the pivot bolts 10 in the scissors arm system. It will be understood that when the bracket 12 on the pivot bolt 10 is displaced forwardly, respecitvely backwardly, this will imply that the

entire scissors arm system will be extended, respectively shortened.

The angular position of the step units is adjusted by means of a longitudinally adjustable element such as a worm screw 50 or the like which is supported in a pivot point 51 on the last step 52 to the left on Figure 1 and a pivot point 53 on the support frame 2, respectively. By for example extension of the element 50 the last step 52 will be forced upwards, having into consequence that all step units simultane¬ ously will be pivoted upwards correspondingly, simultaneously as the end edge on each instep will slide or be displaced upwardly along the adjacent upstep, such that the actual height of the same will be correspondingly reduced.

The width of the casting mould and thereby the width of the stairway moulded therein can be adjusted in several different ways. In the shown solution the mould surfaces for the lateral sides of the stairway are provided by means of adjustable posts 60 which best appears from Figure 5 and which on the inside is provided with mould plates 62. The posts 60 with corresponding equipment are laterally displaceable preferably by means of rollers 64 which are biased against the lateral beams 3,3 on the support beams. The posts 60 include lateral plates 68,68 which are biased against the respective external sides of the lateral beams 3,3 and thereby hold and guide the posts. The posts may be locked in the side position by means of not shown bolts or the like. For determination of the width of the stairway one can arrange either one step unit for each width with upsteps and insteps or, in the preferred embodiment, one utilizes lining boxes which are positioned on the steps against the mould surface 62 , as indicated with stiched lines 65.

The shown casting mould in accordance with the invention will operate and be used in the following fashion.

In the making of an actual stairway the specifications of the stairway will usually be given, for instance the vertical height between the two floors in question, the horizontal projection of the stairway, and possibly also the desired

number of steps in the stairway upon basis of the total height. A usual height of the upsteps is usually 15 to 18 cm.

On this basis the required necessary length of the stairway is clarified, and further is clarified the suitable number of steps in the stairway if these values are not given in the speci ications. The shown casting mould comprises altogether up to 23 possible step units. A straight stairway with more than 23 steps are seldom made. If the stairway which shall be produced for instance comprises 14 steps, the length of the casting mould is defined by means of the worm screw arrangement 40 until the desired length has been set. Thereafter the angular position of the step units is adjusted by means of the adjustment element 50 by which the elevation or height of the systems is being calibrated or set. In some cases one will during adjustment of the casting mould, arrive at that the stairway ought to be increased, respectively possibly reduced, with one step. Such readjustment can simply be carried out by carrying out an extension, respectively a shortening, of the distance L between each step and a suitable readjustment of the height of the upsteps by means of a corresponding adjustment of the angular position between each of the step units. Thereafter the casting mould is being closed off at each side by means of standardized termination units 70,73,75 (indicated with stiched lines) , in order to cast landings at the top and at the bottom of the stairway.

When the various adjustments of the casting mould have been finalized, the mould is being filled with concrete up to the top edge of the mould and one is further filling up the separate mould units at each end in order to make the desired landings at the top and at the bottom of the stairway. The top surfaces of the moulding (the under side of the stairway) is thereafter stripped off by means of a stripping member, whereafter the surface if desired, is dressed or polished.

In regard the width of the insteps, this may be adjusted automatically by means of the casting mould in accordance with the invention. Insteps are normally specified for different widths, namely 250, 275, 300 and 325 mm. For making stairways with the beforementioned different widths one has at hand a set

of insteps with desired width, and the desired set of steps is mounted on the support brackets 22 as shown best in Figure 4. By mounting for instance wider insteps one must normally readjust the distance L between each step unit, i.e. extend this dimension, in order to maintain a right angle between the insteps and upsteps.

It will be understood that by means of the casting mould in accordance with the invention one can carry out a substan¬ tially stepless adjustment of the different specifications of the stairway including the length of the stairway, the dimension between each separate step, the height of the upsteps and one may further by placing insteps with different width, also make stairways having varying widths on the insteps. Also the lateral dimension on the stairways may be adjusted in a very simple fashion.