Well equipment of the kind described above is most often cast in concrete, and the permanently mounted ladder steps serve to facilitate ascending and descending in the well equipment positioned in the ground. Well equipment of this kind is therefore often designated manholes.

It is a recurring task in connection with the manufacture of well equipment to develop processes and process apparatuses that enable rational production of well equipment.

Thus, US patent No 4, 075, 272 teaches an apparatus and a method of the kind described above, whereby the well equipment is provided with a number of ladder steps following removal of the mould core from the ready-cast well equipment by the steps being, by means of an apparatus intended therefor, secured in a number of grippers that will, in a continuous and uninterrupted movement, press the ladder step into the still soft concrete material, and wherein the previously known manual mounting processes are thus avoided, in which a person hammers the ladder steps into the well equipment by means of a sledge hammer.

It is a problem in connection with the prior art process according to US patent No 4, 075, 272, however, that the driving of the ladder steps into the soft mate-

rial involves a risk that considerably weakened areas will form in the concrete as a consequence of a major part of the material that is compacted and re- moved from the mould being-in the area around the place where the ladder step is pressed into the concrete-displaced to provide space for the anchor- ing means on the ladder step, and that weakening lines may thus uninten- tionally occur in the set concrete around the places where the ladder step protrudes into the concrete ; said weakening lines being of such nature that, in a worst-case scenario, there is a risk of the ladder step being, along with a part of the concrete material around same, torn from the well equipment, simply by a load being imposed on the ladder step, but also of small cracks being formed in the concrete with an ensuing increased risk of humidity penetrating into the anchoring means on the ladder steps with an ensuing risk of corrosion.

It is therefore the object of the present invention to provide a method and an apparatus that will, to a higher degree than the prior art, ensure that the per- manently mounted ladder steps remain reliably anchored in the well equip- ment in the short run as well as in the long run.

This is accomplished by the method according to the present invention in that the moulding process uses mould parts for forming said moulding cavity, said mould parts comprising mould elements that will, following discharge from the mould of the cast well equipment, leave a number of mounting apertures in the well equipment, which mounting apertures are located in such a man- ner that the anchoring means of the ladder steps can be driven there into.

Hereby the amount of concrete material to be displaced within the well equipment by driving of ladder steps into the well equipment is reduced whereby the risk of crack formation and the like is reduced considerably.

In order to ensure uniform mounting apertures in all cast units and thus to achieve a higher degree of certainty that mounted ladder steps are securely held, the mounting apertures formed in the moulding process are advanta-

geously subjected to follow-up treatment by a further drilling procedure by means of a drilling device intended therefor.

An alternative simple way of ensuring that the apertures formed in the mould- ing process are uniform can be achieved provided the mould elements that produce the mounting apertures in the well equipment consist of a number of cores that will, during the moulding process, be secured in the mould cavity by means of, and by these mould elements not being removed until the well equipment is completely or partially discharged from the mould core.

Particularly advantageously, the ladder steps are not driven into the well equipment until the cast material well equipment has set sufficiently to ensure that the driving of ladder steps into the mounting apertures will not cause flow or displacement of the casting material around the mounting apertures.

Hereby the driving of ladder steps can further advantageously be performed after removal of the outer mould from the finished well equipment whereby it is possible to remove the outer mould from the cast well equipment at an ear- lier stage. Hereby economies are obtained in terms of process equipment since the outer mould can participate in a renewed moulding process more quickly.

Particularly advantageously the moulding process uses mould elements to form the mounting apertures, which mould elements are left in the well equipment after discharge of the well equipment from the mould, and wherein the mould elements are provided with anchoring apertures that are config- ured with a view to receiving and securing the anchoring means configured on the ladder steps, and wherein the ladder steps are, following discharge of the well equipment with cast-in mould elements, driven into the anchoring apertures of the mould elements. Thus, it is hereby ensured to an even higher degree that the concrete around the mounting apertures is not de- stroyed, the mould elements being per se able to act as reinforcing elements.

Additionally the mould elements can each advantageously be constituted of a substantially cylindrical insert that is preferably made of form-final plastics, such that the mould elements are hereby able to deform plastically and/or elastically when ladder steps are driven into each of the mould elements.

According to a preferred embodiment of the method, the ladder steps are driven into the well equipment by means of an apparatus that comprises a frame on which an arm is configured on which a number of ladder-step grip- pers are arranged, each of which being configured for receiving and securing at least one ladder step, and wherein the frame of the apparatus further comprises holder-on means that extend opposite the above-mentioned lad- der-step grippers, and wherein the apparatus comprises means for forming a substantially continuous and uninterrupted displacement of the ladder-step grippers in a direction towards the holder-on means, and means for stopping this displacement at a predetermined distance between the ladder-step grip- pers and the holder-on means. Hereby an efficient and at least partially automatable process is obtained that can, relatively quickly, drive several ladder steps simultaneously into the well equipment.

In order to ensure against a risk arising, in said automated process, of dam- aging ladder steps and well equipment, the location of the mounting aper- tures in the well equipment is conveniently found by means of sensors in- tended therefor, and by the ladder steps being, prior to being driven into the mounting apertures, displaced with a view to locating each ladder step oppo- site the mounting apertures into which they are to be driven.

As referred to above, the present invention also relates to an apparatus for exercising the method, which apparatus comprises a frame on which is configured a first arm on which a number of ladder-step grippers are arranged that are each configured for receiving and securing at least one ladder step, and wherein the apparatus in characterised in that the apparatus frame is also configured with holder-on means that extend opposite said ladder-step grippers, and wherein the apparatus comprises means for forming a substantially continuous and uninterrupted reduction of the distance between the ladder-step grippers and the holder-on means, and

ladder-step grippers and the holder-on means, and means for stopping this displacement at a predetermined distance between the ladder-step grippers and the holder-on means.

According to a preferred embodiment the ladder-step grippers on the appara- tus are solidly mounted on the first arm, and the means for forming the sub- stantially continuous and uninterrupted reduction of the distance between the ladder-step grippers and the holder-on means are constituted by one or more drive devices that are configured for relative displacement of the first arm with the ladder-step grippers mounted on that arm as a rigid unit in a direc- tion towards the holder-on means. Hereby it is accomplished that the first arm can be configured to be relatively slim, such that the arm can be intro- duced into well equipment having relatively small diameters, it being hereby avoided that it is necessary to provide the first arm with voluminous drive means in the form of eg horizontal, hydraulic cylinders at each ladder-step gripper with a view to displacing the individual ladder steps into the well equipment.

Besides, the apparatus can conveniently comprise a yoke, which yoke has a spacer element mounted in the frame of the apparatus, and wherein the spacer element features two downwardly extending arms that are arranged at an essentially fixed mutual distance on the spacer element, and of which the one arm constitutes said first arm and the second arm constitutes said holder-on means. An extremely stable construction is hereby obtained that is able to effectively absorb the relatively powerful forces that are necessary to accomplish simultaneous driving-in of several ladder steps in a continuous and uninterrupted movement.

The means for driving the ladder steps into the well equipment can hereby advantageously consist of means that are configured with a view to dis- placement of the holder-on means away from the second arm of the yoke and in a direction towards the first arm.

Advantageously, the apparatus according to the invention can be configured such that the first arm is located substantially vertically displaceable relative to the apparatus frame. Hereby the individual ladder steps can, in a simple manner, be raised and lowered relative to the well interior and thereby it is accomplished ia that ladder steps can be located at the desired height in re- lation to the well equipment in alignment with optionally pre-formed mounting apertures in the well equipment.

Besides, the apparatus can additionally and advantageously comprise a de- vice for supporting the well equipment, which device is rotatably arranged relative to the apparatus frame, such that the well equipment can be rotated about a substantially vertical shaft that extends within the well equipment walls. Hereby the correct mutual positioning of mounting apertures, if any, in the well equipment can in a simple manner be effected opposite the ladder steps that are secured in the ladder-step grippers.

In order to compensate for differences in tolerances, if any, in the well equipment the ladder-step grippers are particularly conveniently configured such that the ladder steps secured in the ladder-step grippers can be dis- placed individually a limited distance in all directions relative to the first arm.

Besides, the ladder-step grippers can conveniently be mounted on the first arm at a different distance there from, such that they can be mounted at a distance from the first arm that corresponds to the internal contour of the well equipment.

A preferred embodiment of the invention will now be described in further de- tail with reference to the drawing, wherein : Figures 1 a, b and c show a first portion of an apparatus according to the pre- sent invention in a state that corresponds to an early process step by mount- ing of ladder steps in well equipment, and which apparatus is seen from a first side, a second side and from the top, respectively.

Figures 2a and b show a second portion of an apparatus according to the present invention in the form of a carriage with a piece of well equipment ac- cording to the invention located thereon.

Figures 3a and b show a ladder-step gripper of the type shown in Figures 1 a, b and c in an enlarged view and seen from the front and from above, respec- tively.

Figures 4a, b and c show the portion of the apparatus according to the inven- tion shown in Figures 1 a, b and c and 2a and b in a state that corresponds to a later process step relative to the one shown in Figures 1 a, b and c in the mounting of ladder steps in well equipment, and which apparatus is seen from a first side, a second side and from above, respectively.

Figures 5a, b and c show the portion shown in Figures 4a, b and c of an ap- paratus according to the present invention in a state that corresponds to a later process step relative to the one shown in Figures 4a, b and c in the mounting of ladder steps in well equipment, and which apparatus is seen from a first side, a second side and from above, respectively.

Thus, Figures 1a, b and c illustrate an apparatus for automated mounting of ladder steps in well equipment, which apparatus comprises a frame construc- tion 1 that comprises a vertical frame consisting of two columns 2 and a top beam 3 that serves as upper connector element for the two columns and wherein there is, between the columns 2, arranged a horizontal beam 4 that is journalled to be vertically displaceable between the columns 2 by means of two guides 6 arranged on the columns and a number of rollers 6 configured on the beam. By means of the two hydraulic cylinders 7 the beam 4 can thus be displaced upwards and downwards along the columns 2 and be secured relative to the columns 2 at any height.

At the bottom of the columns 2, a rail groove is provided that consists of the two parallel rails 16 that enable a rail carriage 17 to be displaced towards the columns 2.

As will appear in particular from Figure 1c, the beam 4 is configured as a frame that comprises two longitudinally extending stringers 8 that are, at each end, mutually connected by means of two end stringers 9. Between the two longitudinally extending stringers 8 on the beam 4 a sledge 9 is config- ured that can be displaced horizontally in the beam 4 by means of a set of rollers 10 that run in a guide configured therefor in the longitudinally extend- ing stringers 8. Thereby the sledge 9 can, by means of a hydraulic cylinder 11, be displaced horizontally back and forth in the frame 4, and in principle it can be arranged in any position between the two end stringers 9.

O cs As will appear in particular from Figure 1, the sledge 9 constitutes the upper portion of a yoke that comprises, in addition to said sledge, a first arm 12 and a second arm 13, that are solidly mounted on the sledge 9 whereby the sledge 9 forms the spacer on the yoke that connects the two arms 12, 13.

On the first arm 12 a number (herein five shown as an example) of ladder- step grippers 14 are solidly mounted and on the other arm 13 a correspond- ing number of holder-on means are mounted in the form of hydraulic cylin- ders 15.

Now, Figures 2a and b show a rail carriage 17 that is shown located on the above-mentioned set of rails 16 that extends towards the columns 2 on the apparatus 1 shown in Figure 1 for mounting of ladder steps. Thus, the rail carriage 17 comprises a frame that is provided with a set of rail wheels 18 and having, on its top face, a carrier device 19 that is rotatably mounted about a shaft 20 on the frame 17 of the rail carriage. Hereby, and as illus- trated, a piece of well equipment 21 can be positioned-that is shown herein in a sectional view-and from which it will appear that the well equipment 21 is provided with mounting apertures 22 for receiving anchoring elements on a ladder step (not shown). By combination of Figures 1 and 2 it can be derived that the shown well equipment 21 will be able to be displaced along the rail groove 16 towards the apparatus for mounting of ladder steps, and besides

the well equipment can be rotated relative to this apparatus by means of the rotatable carrier device 19.

Besides, the preferred embodiment of the invention features a (not shown) drive device for controlling the mutual turning of the carrier device 19 relative to the frame 17 of the rail carriage, and hence relative to the ladder-step automaton 1.

As regards the shown well equipment 21 with the pre-formed mounting aper- tures 22 for receiving a ladder step, this well equipment as a part of the pre- sent invention is manufactured in a not shown manufacturing process wherein the ladder-steps apertures can be formed in the casting process as such, as is known eg fra WO patent application No. 9113214. The present invention not being, however, limited to any particular casting process, and any casting process being applicable, these aspects of the invention will not be described in further detail in this context.

Now Figures 3a and b show a ladder-step gripper, of which there are-as mentioned above-located five on the apparatus for mounting ladder steps shown in Figure 1. Each of these ladder-step grippers comprises, as shown, two mounting flanges 23 that can be screwed tightly home on the first arm 12 on the ladder step automaton 1 shown in Figure 1. The mounting flanges are configured such that they can be mounted in different positions on the arm 12 such that the ladder step grippers can be adjusted depending on the type of well equipment to be handled.

Relative to the mounting flanges 23, a gripper device is arranged that com- prises a shelf device 24 on which a ladder step 25 (shown herein by a dotted line) can be mounted with its anchoring elements 26 extending from the shelf device 24. This shelf device is resiliently journalled relative to the mounting flanges 23, such that the shelf element can, to a certain extend, yield to the power influence and is thus able to compensate for various inaccuracies in the production, such as varying element thickness of the well equipment,

varying dimensions of ladder steps, and varying positioning of mounting apertures on the well equipment.

Above the shelf device 24 a set of jaws are provided that are journalled in a shaft 28 relative to the shelf device 24 and in such a manner that the jaws 27 are able to secure the ladder step 25 against the above-mentioned shelf de- vice 24. To this end there is, as shown, configured a hydraulic cylinder 29 that is able to influence the shaft 28 and thereby cause the jaws to rotate, and secure and release the ladder step 25, respectively. Thus, by means of the hydraulic cylinder 29 the jaws 27 can be influenced by a force that is suf- ficient for securing the ladder step ; but being such, however, that small dis- placements of the ladder step 26 relative to the shelf device 24 are allowed in order to further absorb inaccuracies in the production as mentioned above.

As mentioned above, Figures 1a, b and c show the apparatus for mounting ladder steps 25 in well equipment 21 in a first state that occurs at an early stage in a production cycle. Thus, Figure 1 shows the ladder step automaton 1 in a state in which ladder steps 25 are mounted in each of the ladder-step grippers 14, such that the anchoring elements 26 on the ladder steps 25 ex- tend in a direction away form the first arm 12 and towards the second arm 13.

The mounting of ladder steps 25 in the individual ladder-step grippers 14 can be performed either manually or there can be configured a not shown automaton to this end.

Now, Figures 4a, b and c show the same apparatus as shown in Figure 1.

Here it is shown, however, that a rail carriage 17 with a piece of well equip- ment 21 is arranged at the ladder-step automaton 1, and wherein the beam 4 has, by means of the hydraulic cylinder 7, been raised and subsequently low- ered to the position shown, wherein the first arm 12 with the ladder steps 25 secured in the ladder-step grippers 14 extends a distance down into the inte- rior of the well equipment 21.

In a preferred embodiment (not shown) the first arm 12 features an optical sensor that is capable of recording the distance from the sensor to the well equipment 21 and of finding at least one of the shown mounting apertures 22 in the well equipment 21. The latter functionality can, in a convenient em- bodiment, be performed by use of a laser-measurement device attached to the first arm 12, and by raising and lowering, respectively, the first arm 12 while simultaneously the well equipment 21 is rotated back and forth by means of the rotatable carrier device 19, until the location of the afore- mentioned aperture has been recorded.

Now the individual ladder steps 25 and their anchoring means 26 can be po- sitioned correctly opposite the respective mounting apertures 22, and the anchoring means can, as shown in Figures 5a, b and c, be pressed into the mounting apertures 22 by the holder-on means being, by means of the hy- draulic cylinders 15, capable of pressing the well equipment 21 towards the ladder steps 25.

As shown in Figures 4 and 5 the pressing action is obtained by the well equipment 21 being kept on the same position relative to the rail path 16, and by the yoke with the fixed arms 12 and 13 being displaced relative to the beam 4 while simultaneously the holder-on means are displaced opposite the yoke and at a corresponding velocity and travelling by means of the hydraulic cylinders 15. This process continues until the ladder steps 25 have been pressed a predetermined distance into the well equipment 21, which can op- tionally be recorded by means of the above-mentioned (not shown) optical sensor.

As shown in the figures the individual ladder step grippers can be mounted at varying distances from the first arm 12, such that the ladder-step grippers can be adjusted to optional mounting of ladder steps in well equipment with varying diameters or element thicknesses.

Now the ladder-step grippers are able to release the individual ladder steps, and the ready-mounted well equipment can be removed from the ladder-step automaton 1, following which the afore-mentioned process can be repeated with a renewed piece of well equipment.