WO1993019913A1

WO1993019913A1 - A mould device for casting concrete well rings or cones having ladder steps

Info

Publication number: WO1993019913A1
Application number: PCT/DK1993/000120
Authority: WO
Inventors: Johannes Hvidegaard
Original assignee: Betodan A/S
Priority date: 1992-04-01
Filing date: 1993-03-31
Publication date: 1993-10-14
Also published as: DK43992D0; DE9303730U1

Abstract

A mould device (1) serves to vertically cast tubular articles, such as well rings or cones having embedded ladder steps (2), of concrete or a similar material in one operation. The device comprises a hollow core (3) having a wall (6). This wall is formed with a vertical, upwardly opened cut-out (11) for the free passage of the steps (2) when the cast article is displaced vertically with respect to the cores (3) during demoulding. During casting, this cut-out is closed by a laterally hinged door (13) having introduction openings (10) for the steps. The steps are retained during casting by grippers (19), each of which has upper and lower jaws (23, 24) for clamping the step. During this the outer ends of the grippers (19) are locked in the introduction openings (10) of the door (13). The grippers can be reciprocated by means of a parallel guide (20). Uniform, safe and durable embedment of the steps is obtained by means of the mould device. The working procedure moreover proceeds easily and rapidly without operation stoppages. Wear on the mechanical parts is minimized.

Description

_ _

A mould device for casting concrete well rings or cones having ladder steps

The invention concerns a mould device for vertically cast- ing tubular articles of concrete or a similar material in one operation, such as well rings or cones having embedded ladder steps, comprising a hollow core having a wall which has at any rate one upwardly open cut-out for the free passage of the steps when the cast article is displaced with respect to the core during demoulding, said core moreover containing means which are adapted such that they can close the cut-out and retain the steps in position during casting and be moved out of the path described by the steps during demoulding.

In many countries the authorities demand that well ar¬ ticles of concrete shall be provided with embedded ladder steps. Owing to the safety of the individuals using the steps during their work, very strict demands are moreover made on the reliability and durability of the embedment. Previously, the steps were generally embedded manually, holes being cut in the precast well article which were then filled with fresh concrete after insertion of the legs of the steps. The quality of such an embedment, how- ever, is very uncertain and greatly depends upon the care and conscientiousness devoted to the performance of the job. The connection between the old and the new concrete in the embedment holes may moreover be more or less strong and sometimes so deficient that the step will not be fixed sufficiently firmly. To this should be added that the ma¬ nual embedment method is both slow, cumbersome and labour intensive.

A mould device serving to remedy the above-mentioned draw- backs -is known from DE patent specification 3110185. By means of this mould device the steps can now be embedded in the same operation as the casting of the actual well article. Slots are cut in the wall of the core for this purpose which permit each step to be introduced and be placed on a holder provided on the inner side of the wall. Part of the wall of the core constitutes an independent core segment which can be pulled into the core to enable unobstructed passage of the steps during demoulding. Furthermore, fixing means are provided to retain the steps on the holders during casting. In one version of this structure the holders are arranged on the firm part of the wall of the core, and in another the holders are arranged on the core segment. In both cases the fixing means are arranged on the core segment and thus follow the movements of said segment.

The use of this known mould device has considerably faci¬ litated the previously cumbersome manual operation of em¬ bedding the ladder steps, and these can now be embedded with greater security and accuracy than before. However, it has been found that the device is not perfect, but is vitiated by serious drawbacks.

Thus, concrete will inevitably penetrate through the gaps left when the steps are inserted through the slots in the core wall to be placed on the respective holders. Owing to their shape the steps themselves are not capable of fill¬ ing these gaps, which cannot be closed by rubber strips either which the fixing means have tried to press down over the steps. These rubber strips moreover tend to tilt the steps so that they will be positioned loosely in the well casting when the rubber strips elastically change their shape upon relief of the fixing means. Part of the penetrated concrete will settle on the holders or drop down into the core, and in both cases this may give rise to serious operation stoppages. Other parts of the pene- trated concrete can settle on the step or the surrounding concrete wall as more or less sharp deposits, which may cause trouble to the individuals climbing the steps, and the deposits also detract from the appearance of the cast- ing. These circumstances require frequent cleaning of the core and its mechanical parts, and it is often necessary to perform a manual subsequent treatment of the finished well ring interiorly around the steps and to clean these of concrete deposits.

To obtain sufficient space for the steps to pass freely during demoulding, the core segment must necessarily occupy a considerable portion of the overall core wall, whose cut-out therefore has a very long free edge which is to be" closed tightly by a corresponding edge on the core segment during casting. However, in this operation the core segment is held in position solely by the pressure from a pneumatic cylinder, and it is therefore very diffi¬ cult to obtain sufficient tightness along the whole length of this long line of contact between the two edges, which therefore tend to knock against each other under the vi¬ brations, causing rapid wear. When the core segment thus works with respect to the actual core, the steps cannot be firmly retained during moulding and be embedded with the required great certainty.

The first version of the device in which the holders are arranged on the firm core wall, can maximally be used for only two steps. In the second version in which a larger number of steps can be embedded, the holders are arranged on the core segment and therefore tend to loosen the al¬ ready embedded steps when the core segment is pulled into the core during the demoulding operation. This pull-in operation takes place translatorily at right angles to the axis of the core, and the top side of the core segment is therefore offset below the cover of the core. Thus, be- tween these two parts there is formed a depression which is filled with concrete during casting that falls down along the core or the wall of the core segment or into the core, and in this case too the excess concrete may give rise to operation stoppages and imperfect castings.

Because of the considerable drawbacks and defects, which are present i.a. in the above-mentioned DE patent specifi¬ cation 3110185, there is a pronounced need for a more sofisticated mould device for casting well articles of concrete, e.g. well rings and cones with embedded ladder steps, in one and the same operation. In relation to the prior art, this device is to be capable of working more rapidly and easily, of repeatedly producing a high quality product with a perfect appearance and with steps which are embedded accurately and correctly each time with a uniform safe and durable connection and without being covered to a greater or smaller degree by excess concrete in the form of more or less sharp deposits, which might cause incon- venience and be a danger to an individual climbing the steps, and which might possibly tear and injure this indi¬ vidual's hands. The device must moreover be capable of operating efficiently without operation stoppages for an extended period of operation without considerable wear on the individual components of the device. The object of the invention is to provide such a mould device.

Another object of the invention is to provide a mould de¬ vice of the type mentioned in the opening paragraph whose means for retaining the steps during casting are simultan¬ eously incorporated as a direct link in an automatic posi¬ tioning process.

A third object of the invention is to provide a mould de- vice of the type mentioned in the opening paragraph which is provided with a positioner device or a magazine for the automatic positioning process.

The invention is novel and unique in that the means for retaining the steps during moulding consist of a gripper associated with each step and having jaws capable of being moved by a drive mechanism between an open position in which the jaws can gape over a step, and a closed position in which the jaws can clamp the step. The steps can hereby be retained effectively during casting. The gripper simul- taneously eliminates the necessity of using the slot known from DE patent specification 3110185 for introducing the step. The jaws of the gripper close directly around the step from their respective sides to ensure that no exces¬ sive concrete enter and settle as inconvenient and sharp deposits on the step or enter the mechanical parts of the mould device, where said concrete might give rise to se¬ rious operation difficulties and stoppages.

In an advantageous embodiment the gripper comprises a fork consisting of a transverse member having a leg arranged at each end, a shaft which extends horizontally between the two legs and on which the jaws are pivotally arranged, as well as a rearwardly directed fixed arm associated with each jaw, said drive mechanism comprising a screw spring arranged e.g. around the shaft for opening the jaws and a wedge arranged between the legs for driving inwardly be¬ tween the arms on the jaws and closing these by means of e.g. at least one pneumatic or hydraulic drive cylinder. This structure is simple and inexpensive and is capable of working with great reliability in operation over an ex¬ tended period of time. The jaws can gape very widely at the outer end and can therefore pass and close behind undercut high parts on the step close to the inner side of the well article. The effect of the wedge simultaneously ensures that the jaws are clamped tightly and fixedly together around the step and are capable of holding it in precise position during the entire casting process.

It is important that the jaws are opened exactly simultan¬ eously during demoulding, since, otherwise, they might easily inadvertently push the step now embedded and loosen it. This is achieved by driving the wedge translatorily inwardly between the arms of the jaws, which are thereby forced to move together constantly during opening and closing. With this end in view the edge may have a tongue at each end and each of the legs of the fork may have a horizontally extending groove complementary to the tongue, which ensures that the wedge can only be displaced hori¬ zontally to and fro.

In a simple structure for reciprocating the grippers be¬ tween their casting position and a position in which they are clear of the path described by the steps during de¬ moulding, the fork of the grippers is arranged on a common horizontal beam, which can be displaced horizontally to and fro by e.g. at least one pneumatic or hydraulic drive cylinder in a parallel guide.

In an advantageous second embodiment the fork of each of the grippers is carried by at least one separate rod, which can be displaced to and fro by means of e.g. at least one hydraulic or pneumatic cylinder in a parallel guide and move the gripper to a position outside the core or the casting position and out of the path described by the steps during demoulding, respectively. This embodiment is particularly suitable for incorporation in an automatic positioning process, since the gripper is capable of reaching out of the core and itself collecting a step from a positioner device or a magazine.

The space in the interior of the core and the relatively small horizontal spacing between the individual steps en- tail that the structure for reciprocating the gripper must be relatively compact and have a small height. This is achieved when the structure is adapted such that the pa¬ rallel guide for the rod consists of an outer pipe secured in the interior of the core and having an e.g. circular cross-section, that the rod for carrying the fork of the gripper consists of an inner pipe slidably arranged in the outer pipe, and that the drive cylinder for the wedge is provided at the front end of the inner pipe and the drive cylinder for slidably moving the inner pipe at the rear end of said inner pipe. The mechanical parts for advancing the gripper are thus well-protected in the outer pipe against contamination in the tough and streneous environ¬ ment that exists during casting. The structure is there- fore very reliable in operation.

In the uppermost area of a core for casting e.g. well rings the space available transversely for incorporation of an advancing mechanism may be restricted. For a suffi- ciently great movement of the advancing mechanism to be obtained in this case too, the said mechanism may be con¬ structed as a telescope, there being provided between the inner pipe and the outer pipe an intermediate pipe capable of being reciprocated in the outer pipe by means of a drive cylinder provided in the intermediate pipe, so that the inner pipe can be reciprocated in the intermediate pipe by means of the drive cylinder provided at the rear end of the inner pipe.

During casting the vertical cut-out in the core for the free passage of the steps during demoulding must be closed for making the outer mould of the core. With this end in view a laterally hinged door may advantageously be used, which can be opened and closed by means of e.g. a pneuma- tic or hydraulic drive cylinder, and which has an intro¬ duction opening for each step. The hinge forms an inexpen- sive and effective means for safely guiding the door into position in the vertical opening of the core and keeping it in position there during casting, without it being cap¬ able of working with respect to the rest of the core.

With a view to obtaining a smooth wall in the well article around each of the embedded steps, the vertical outer side of the gripper may have the shape of a cylinder with the same radius as the outer side of the core and be present at the same distance from the axis of the core during casting. The introduction opening for each step must therefore be so large as to be capable of accommodating the outer end of the gripper. For the introduction opening to be closed completely in this situation, preventing con- crete-from entering, the outer end of the gripper must fill the opening completely. This is obtained when the in¬ troduction opening for each step is defined by the edges in a horizontal cut in the free side of the door facing oppositely to-the hinge and an edge in the vertical cut- out in the core when the door is closed, when the outer end of the gripper with closed jaws has a shape complemen¬ tary to the introduction opening thus formed, and when the rest of the gripper has a height which is equal to or smaller than the height of the cut. This structure addi- tionally entails that, after casting, the door can freely be opened without touching the gripper, whose jaws are still kept clamped around the embedded step at this time.

To ensure that the steps are embedded with a reliable and durable connection, it is necessary that they do not move with respect to the poured concrete when this is vibrated. Since the gripper holding the step is completely fixed itself in the surrounding introduction opening in the door, the condition of safe embedment of the step is that the door is retained carefully by the rest of the core and thus closely follows the movements of the core during the vibrations, which may e.g. have a vertical amplitude. At one side the door is effectively secured by the hinge, while the free side of the door can be secured vertically by horizontal projections which are provided in the verti- cal cut-out of the core and intimately engage the horizon¬ tal cuts of the door, the upper and lower edges of each of these extending past the gripper when the gripper is pre¬ sent in the casting position and the door is closed.

When the edges in the cuts of the door are bevelled with faces forming an acute angle with the inner side of the door, and the outer end of the gripper with corresponding faces, the corresponding faces in the door and the outer end of the gripper, respectively, will be in close contact with each other when the gripper is pressed against the door by an inwardly directed force. The gripper is hereby capable of sealing the introduction opening completely against ingress of concrete, while the gripper is locked firmly in the door so that the gripper closely follows the movement of the door and thereby of the entire core during the vibration process.

To obtain an effective seal also at the free edge of the door facing oppositely to the hinge, this, too, may be bevelled ^"with a face forming an acute angle with the inner side of the door, and the corresponding edge in the verti¬ cal cut-out of the core may be bevelled with a face form¬ ing a correspondingly acute angle with the outer side of the core.

Finally, the entire arrangement for retaining the step during casting and vibration with respect to the core, consisting of the gripper which is locked in the door and the door which is in turn locked vertically by the hinge and the projections in the vertical cut-out of the core, may be locked horizontally as well by means of a locking device, e.g. a barrel bolt for locking the door from with¬ in during casting.

Normally, the core is upwardly closed by a firm cover. To obtain free passage for the steps during demoulding in this case too, the vertical cut-out in the core may con¬ tinue in a horizontal cut-out in the cover, and this hori¬ zontal cut-out may be closed during casting by a laterally hinged flap that can be opened and closed by means of e.g. a pneumatic or hydraulic drive cylinder.

As mentioned before, the grippers and their advancing mechanism may have a structure such that they can readily serve as parts of an automatic positioning process, which moreover consists of an positioner device located outside the core and having holders for placing each step in ad¬ vance in a position from which the gripper itself can col¬ lect the step and place it in casting position in the core.

In a simple and practical embodiment of the positioner de¬ vice, this may consist of at any rate a vertical, rotat- able shaft with slits for insertion of the legs of the steps, said shaft being rotatable by means of e.g. a ro- tary cylinder between an angular position in which the slits are in a convenient position for insertion of the steps, and a position from which the inserted steps can be collected by the gripper.

The positioning process may be automated additionally by means of a magazine positioned outside the core and hav¬ ing, opposite each of the introduction openings of the core, a section which can accommodate a stack of steps, a pneumatic or hydraulic cylinder being provided for each section for pushing the lowermost step in the stack inwardly between the open jaws in the respective gripper when the gripper is in the gripping position outside the core.

The invention will be explained more fully by the follow- ing description of embodiments which just serve as ex¬ amples, and with reference to the drawing, in which

fig. 1 is a vertical sectional view of mould device ac¬ cording to the invention,

fig. 2 is a sectional top view from above of the same,

fig. 3 is an enlarged vertical section through one of the grippers associated with the mould device shown in figs. 1 and 2, in the casting position with the jaws clamped around a step,

fig. 4 shows the same, but with open jaws,

fig- 5 shows the same, but pulled completely clear of the embedded step,

fig. 6 is an enlarged horizontal section, seen from above, through a fragment of the mould device shown in fig. 1 with a first embodiment of a parallel guide for a gripper,

fig. 7 is a partially sectional top view of a second em¬ bodiment of a parallel guide for a gripper,

fig. 8 shows a core with a common parallel guide for all the grippers,

fig. 9 shows the same, but seen in section from above,

fig. 10 shows a section along the line X-X in fig. 2, fig. 11 is a lateral view of a core with a positioner de¬ vice positioned outside the core,

fig. 12 is a top view of the same,

fig. 13 is a lateral view of a core with a magazine posi¬ tioned outside the core, and

fig. 14 is a top view of the same.

Figs. 1 and 2 show a mould device according to the inven¬ tion. In this case, the mould device, which is generally designated 1, is intended for casting well rings (not shown) with embedded ladder steps 2. The device comprises a core 3 and an outer mould section 4 positioned around the core, as well as a lower profile ring 5 for carrying the well ring and forming its spigot end. The core 3, which is hollow, is composed of a plate with a cylindrical wall 6, a base plate 7 and a top cover 8. During produc- tion, the core is fixed in a casting machine (not shown) having a vibrator 9 for vibration and compaction of the concrete, which has been filled from above down into the gap between the core and the outer mould section. In those cases where the well ring is to have a socket end at the top in addition to the lower spigot end, the socket end is formed by pressing a profile ring (not shown) down into the poured concrete. When the compaction of the concrete has been completed, and the well ring is to be demoulded, this takes place in that the outer mould 4 is pulled me- chanically vertically upwards until it has been lifted so much that it is completely clear of the well ring. Then the well ring standing on the profile ring 5 is lifted vertically clear of the core, and then the well ring is driven out to a storage location where it can stand until its concrete has set and hardened sufficiently. The casting process described above is of a quite tradi¬ tional type and usually proceeds without any problems in connection with the demoulding. However, when the well ring is to be provided with steps which are embedded con- currently with the casting of the well ring, the well ring cannot readily be lifted vertically ckear of the core. The reason is that part of each step is now present outside the core, embedded in the well ring, while the rest of the step extends transversely through the wall of the core via an introduction opening 10 and into the core itself.

Therefore, in the area at the steps the core is provided with a vertical cut-out 11 which merges into a horizontal cut-out 12 in the cover. Since the wall of the core is thus removed completely from the path described by the steps- during demoulding, the well ring can now be moved freely upwards with respect to the core, without the steps thereby being knocked off by contact with the uppermost edges in the introduction openings 10.

However, the core must necessarily be closed during the casting process, and with this end in view it has a door 13 for each vertical cut-out, said door being pivotable by means of a cylinder 15 about a vertical hinge 14 between a position in which the door closes the cut-out, and a posi- tion in which the door is displaced from the vertical path described by the steps during demoulding. The door is cy¬ lindrical with the same radius of curvature as the core, and in the closed position it fills the vertical cut-out

11 completely and thus forms a continuation of the firm core wall. The previously mentioned introduction openings

10 for the steps are provided in the door. Their shape will be described in detail below. The horizontal cut-out

12 in the cover 8 is closed correspondingly during casting by a flap 16, which can pivot about a horizontal hinge 17 by means of a cylinder 18. As shown in fig. 2, two vertical rows of steps are pro¬ vided in this case which are angularly offset with respect to each other. Cut-outs 11, 12 are associated with each row of steps for the free passage of the steps during de- moulding, and these cut-outs can be closed by the door and the flap 13, 16, respectively, during casting. For cla¬ rity, the two rows of steps are shown in fig. 1 as if they were positioned in a single vertical line. The gripper is moreover shown in different situations to illustrate its function. In practice, all the grippers of course move together in a working cycle.

Each step is carried and retained during casting by a gripper 19, which can be reciprocated by a parallel guide between a casting position and a position in which the gripper is pulled completely out of the path described by the steps during demoulding. The rear end of each parallel guide 20 is secured on the core wall diametrically oppo¬ site the associated introduction opening 10, while the front end of the parallel guide is secured on a horizontal beam 21, which is in turn secured on two vertical columns 22, which are upwardly secured to the top cover 8 and downwardly to the base plate 7.

The gripper and the associated parallel guide are shown in greater detail in figs. 3-6, in which, however, the paral¬ lel guide is just shown in fraction. The gripper comprises upper and lower jaws 23, 24 which are pivotally arranged about a horizontal shaft 25. The ends of this shaft are mounted in their respective legs 26 in a fork 27 which moreover comprises a transverse member 28. The fork 27 is in turn secured on the end of a horizontal rod 29 which can be reciprocated in a pipe 30, the rod sliding in bush¬ ings 31. In the embodiment shown in figs. 3-6 both the rod 29 and the pipe 30 are rectangular, and the rod 29 itself is moreover shaped as a rectangular pipe. The rear end of the displaceable, tubular rod 29 is closed by a rear end wall 32, and the front end of the rod is closed by the transverse member 28 of the fork 27. The interior of the rod 29 is moreover divided by a partition 33 into a front, relatively short chamber 34 and a rear, longer chamber 35. The rear chamber accommodates a rear piston 36 with a piston rod 37 extending through the rear end wall 32 to the wall 6 of the core to which it is se¬ cured. The rear end part of the rod 29 is thus constructed as a cylinder capable of pushing the rod to and fro in the outer pipe 30, when the rear chamber 35 receives e.g. com¬ pressed air on either the one or the other side of the rear piston 36. The air can be fed from a line which is connected with the rear end of the piston rod 37, which can then be constructed as a double pipe, the inner one of these pipes terminating to the left of the piston 36, and the outer pipe having one or more openings close to the right of the piston 36. This arrangement of the air supply is not shown.

Correspondingly, the front chamber 34 accommodates a front piston 38 having two piston rods 39 in this case, which extend through the transverse member 28 to a wedge 40 which is firmly connected with the two piston rods 39. Also the front end part of the slidable rod 29 is thus constructed as a cylinder which can push the wedge 40 to and fro corresponding to the stroke in the front chamber 34 when the chamber receives e.g. air on the one or the other side of the piston 38. In this case, too, the air can be fed via the rear end by the rear piston rod which is then provided with an additional inner double pipe for this purpose, said inner double pipe extending right up to the front chamber. Nor is this arrangement shown.

Each of the jaws is provided with a rearwardly directed arm 41 and 42, respectively. When the wedge 40 is driven by the piston 38 and the piston rod 39 inwardly between these arms 41, 42, the jaws 23, 24 close around the step 2, as shown in fig. 3. When the wedge is retracted again, as shown in fig. 4, the jaws are again opened by a screw spring 43 positioned around the swivel shaft of the jaws. The jaws are now completely clear of the step 2 and can therefore be pulled clear of this, as shown in fig. 5, the rod 29 being retracted into the outer pipe 30 by activa¬ tion of the cylinder arrangement in the rear chamber 35 of the rod.

Each of the jaws has a rib 44, 45, respectively, on the internal side immediately in front of the shaft 25. On the upper rib 44 there is arranged a rubber strip 46 which, as shown- in fig. 3, closes tightly against the lower rib 45 when the jaws are closed. This rubber strip 46 serves to protect the pivot bearing of the jaws against ingress of concrete during casting, and to provide an additional elastic force initially during opening of the jaws where these still adhere to the poured concrete. The lower rib 45 also serves as a stop in the introduction of the step 2, which is moreover positioned by a second, but lower rib 47, this rib 47 is adapted such that the step will stick to the rib, when released, even though the jaws have not closed yet.

The shape of the jaws must be adapted to the actual steps to be embedded. In the shown case the step 2 has an out¬ wardly protruding rib 48 along each side edge to impart to the step the necessary moment of resistance for the step to support the weight of a person, standing on it, with certainty. The ribs 47 continues into the legs 49 of the step via inwardly extending bends 50. The upper jaw 23 must therefore be capable of being opened relatively much to get behind the undercut portion of the ribs 48 at the bend 50. On the other hand, the lower jaw 24 is just to be able to open precisely so much as to get clear of the underside of the step. The pivotal movement of the two jaws around the shaft 25 therefore does not have to be of the same size. However, it is important that they move closely together when being opened prior to demoulding to be pulled clear of the step. If this requirement is not satisfied, the clamping force of the jaws around the step will not be relieved at precisely the same time, which results in an instantaneous power component which will try to loosen the embedded step. To synchronize the pivotal movements of the jaws completely, each end of the wedge 40 is provided with a tongue 51 which is inserted as a tight slide fit in a horizontal groove 52 in the inner side of each of the legs 26 of the fork 27. The wedge is hereby guided such that .during its movement it is forced to follow a rectilinear path precisely, thereby controlling the pivotal movements of the jaws in synchronism.

In the casting position of the gripper the outer end of the gripper is present, as shown in fig. 3, in the intro¬ duction opening 10 of the door 13. The outer sides 53 and 54, respectively, of the jaws, which directly contact the concrete during casting, are cylindrical with the same radius as the core, but extend so much obliquely inwardly that, when opened, the jaws do not deform the poured con¬ crete. This special shape of the outer sides 53, 54 of the jaws also provides the advantage that a reinforcement 55 is provided at the point in the well ring where the step is fixed.

The outer end of the gripper fills the opening 10 com¬ pletely and is provided with inclined faces which, in the casting position of the gripper, engage corresponding in¬ clined faces 56, 57, which are bevelled on the edges of the introduction opening 10 with an acute angle with re¬ spect to the inner side of the door. This inclined bevel ensures complete seal against ingress of concrete between the gripper and the door. A correspondingly good seal is provided between the gripper and the step when the jaws close around it, it being possible to adapt the complemen- tary shapes of the gripper and the step to each other with an accuracy which is just limited by the manufacturing to¬ lerances of the step, which, however, may be very small when the step is e.g. cast. The large open gap present in the slits serving to introduce the steps in the structure known from DE patent 3110185 is thus eliminated complete¬ ly-

Fig. 10 shows the complete arrangement from within. As shown, there are two rows of steps, each having its own vertical cut-out and associated door 58a, 58b, respective¬ ly. The doors are swingably mounted on vertical shafts 60a, 60b by means of bearings on the door and the firm core wall 59a, 59b; 61a, 61b, respectively. Drive cylin¬ ders 62a, 62b,- which may e.g. be pneumatic, serve to open and close the doors. The drive cylinders are mounted below the doors in the shown case, but may be positioned higher up on the shaft, if desired, and there may also be more than one drive cylinder for each door. The vertical cut¬ outs and the doors can moreover extend right down to the base plate 7 of the core. When the doors are open, there is free access in the overall height of the core to its interior for maintenance and repair of the mechanical parts located here and possibly cleaning of concrete that might have entered the core.

The introduction openings for the steps are in the form of horizontal cuts 63a, 63b, which extend from the free edges 64a, 64b of the doors inwardly over and enclose the grip¬ pers 65a, 65b intimately when the doors are closed. The grippers have their greatest height at the outermost end located in the cuts 63a, 63b when the doors are closed, and for demoulding the doors can therefore be readily opened widely without pushing the grippers and thereby the steps which are still retained by these. The doors close against edges 66a, 66b on a common central bar 67. As shown best by fig. 6, the edges 66a, 66b are bevelled obliquely with a face forming an acute angle with the outer side of the bar. Owing to this bevel complete seal against ingress of concrete is obtained when the door is closed, and the bevel moreover entails that the vertical axles 60a, 60b and thereby the pivot axes of the doors can expediently be located within the core wall which can thus extend contiguously past the shaft.

On each side the bar 67 is provided with horizontal pro- jections 68a, 68b which, in the casting position of the grippers 65a, 65b and with closed doors, extend so far inwardly as to contact the grippers through the cuts 63a, 63b, which are filled completely by the projections.

The inner side of the bar 67 moreover mounts a barrel bolt 69 which can be moved up and down in bearings 70 by means of pneumatic cylinders 71. A plurality of locking plates 72 are mounted on this barrel bolt 69 which extend past a plurality of corresponding locking plates 73 on the doors, . which are thereby locked effectively when the barrel bolt is moved in the direction shown by the arrows to its upper position.

All parts of the arrangement are now mutually locked com- pletely together so that none of the parts can move with respect to the others during the vibration process. The steps are kept tightly squeezed by the jaws of the grip¬ pers, which are locked in the cuts of the doors, which are in turn locked vertically by the projections of the cen- tral bar. Finally, the doors are locked against backward pivotal movement by means of the barrel bolt 69. In this manner the steps are kept completely at rest in the mould device during casting and the vibration process, thereby ensuring that the steps are embedded in an absolutely safe and durable connection.

As mentioned before, the top cover 8 of the core is formed with a horizontal cut-out 75a, 75b, associated with each row of steps, for the passage of the steps during demould¬ ing. During the casting process these cut-outs are closed by flaps 76a, 76b, which can be opened and closed by e.g. pneumatic drive cylinders 77a, 77b.

When the well ring has been compressed and is to be de- moulded, these flaps 76a, 76b are opened, and the barrel bolt 69 is moved downwards, following which the doors 58a, 58b open. Then the jaws open and are pulled clear of the steps by their parallel guide. The finished well ring with embedded steps can now be lifted vertically clear of the core without any difficulty.

Fig. 7 shows a second embodiment of a parallel guide for a gripper. In this case, instead of the single rectangular outer pipe 30 in the first embodiment shown in figs. 3-6, two circular, outer pipes 78 are provided, each having its own circular, tubular rod 79 which carries the fork 27 of the gripper 19 and can be reciprocated in the outer pipe 78. The structure has the advantage that it can be built from standard components having a relatively low weight.

In the casting of well cones the length available trans¬ versely for incorporation of the parallel guide upwardly in the core may be limited. In this case a variation (not shown) of the second embodiment may be used, which is then built in the form of a telescope with an intermediate pipe interposed between the inner and outer pipes. Figs. 8 and 9 show a third embodiment of a parallel guide in which all the grippers are now arranged on a common vertical beam 80 by means of inclined flaps 81, on which drive cylinders 82 are arranged for the wedges in the individual grippers. The vertical beam 80 upwardly and downwardly mounts a sliding sleeve 83 which can be reci¬ procated on rods 84 by means of e.g. pneumatic drive cy¬ linders 85, said rods 84 extending horizontally diametri¬ cally across the core centrally between the two rows of steps.

Figs. 11 and 12 show two positioner devices 86 for their respective rows of steps. Each positioner device has a vertical shaft 87 which can be rotated by means of a ro- tary cylinder 89 in bearings 88 between a position in which the steps can conveniently be placed in the intro¬ duction device, and a position in which the gripper itself can collect the step and place it in the casting position. A block 90 is secured on the shaft 87 for each step, said block having a slot 91 fitting the leg of the step.

In fig. 11 the leg of the uppermost step is being inserted into the slot. The step remains firmly positioned in this gap because of the fixing moment from the action of the force of gravity on the free part of the step. If desired, one or more springs may additionally be mounted in the slot for e.g. engaging notches in the legs to additionally secure the retention of these. The next step has been turned into position opposite the respective introduction opening ready for collection. Then the gripper is pushed out of the core with the jaws extending around the step, following which the jaws close, and the gripper finally pulls the step into the casting position. These sequences are shown separately in fig. 11, but of course take place at one and the same time in practice. When the shown posi¬ tioner device is used, the operator can place the steps at a suitable time during the working cycle, and the grippers themselves can later rapidly collect all the steps at one time and place them in the casting position. Another ad¬ vantage is that the operator can place the steps in a con- venient position and take them from a supply which is lo¬ cated close to the positioner devices, but nevertheless suitably spaced from the area directly around the mould device and the casting machine. It is moreover easier and ergonomically more correct to carry and hold the steps in their tread and holding parts than in their legs.

In figs. 13 and 14 the positioner device is replaced by a magazine 92 for each row of steps. For each step, this magazine has a section 93 capable of accommodating a stack of steps 94. Apart from the lowermost step the stack 94 is carried by one or more pawls 95. The lowermost step can therefore be pushed freely into the open jaws of the grip¬ per by means of e.g. a pneumatic cylinder 96. For each working cycle the magazine then releases a new step. The actual embodiment of the magazine is of a generally known type and will therefore not be discussed more fully here.

When use is made of the advantageous embodiment in which positioner devices are associated with the core and the grippers are equipped with their respective parallel guides of the type capable of moving the grippers to a free position entirely outside the wall of the core, the working process is as follows:

- The operator has inserted the steps to be embedded into the slots of the positioner devices at a suitable time during the working cycle.

In the starting position the doors are open and the grippers with open jaws have been retracted after de¬ moulding of the previous well ring. The gripper device is rotated to collection position and the grippers are pushed out to collect the steps, while the doors are closed after the grippers and are bolted from within.

The grippers clamp the steps and pull them into the casting position where they are kept suitably pressed against the obliquely bevelled edges in the cuts of the doors by the drive cylinders of the parallel guides.

The positioner devices are rotated back to insertion position, and the profile ring and the outer mould are placed in position around the core. The mould is filled with concrete which is vibration compacted.

The outer mould is lifted vertically clear of the cast well ring.

The doors are unlocked and opened.

The grippers are opened and pulled clear of the em¬ bedded steps.

The cast well ring is lifted clear of the core.

The description above and the drawing relate to an embodi¬ ment of a gripper with jaws which pivot about a common shaft and are opened by a spring and closed by a wedge which is driven from behind inwardly between the rear- wardly directed arms of the jaws. However, this embodiment just serves as an example, since many other embodiments are conceivable within the scope of the invention. Thus, each of the jaws may have its own pivot shaft and be opened by an oppositely directed wedge connected with the closing wedge, and the gripper may also be provided with parallel-displaceable jaws. Further, in addition to pipe and sliding sleeve guides, other forms of guides may be used as a parallel guide for the gripper, e.g. slide or link guides.

Instead of a barrel bolt for locking the doors from with¬ in, any other locking mechanism may be used.

The various embodiments of the mould device have been de¬ scribed on the assumption that the well article was cast of concrete. However, other expedient materials, e.g. sulphur concrete, may be used equally well.

It is moreover noted that the term step is to be construed as a generic concept comprising all forms of similar parts that can be embedded in the inner side of well articles while these are cast.

Claims

P a t e n t C l a i m s :

1. A mould device for vertically casting tubular articles of concrete or a similar material in one operation, such as well rings or well cones having embedded ladder steps, comprising a hollow core having a wall which has at any rate one upwardly open cut-out for the free passage of the steps when the cast article is displaced with respect to the core during demoulding, said core moreover containing means which are adapted such that they can close the cut¬ out and retain the steps in position during casting and be moved out of the path described by the steps during de¬ moulding, c h a r a c t e r i z e d in that the means for retaining the steps during casting consist of a gripper associated with each step and having jaws which can be moved by means of a drive mechanism between an open posi¬ tion in which the jaws can gape over a step, and a closed position in which the jaws can clamp the step.

2. A mould device according to claim 1, c h a r a c ¬ t e r i z e d in that the gripper comprises a fork which consists of a tranverse member having a leg arranged at each end, a shaft which extends horizontally between the two legs and on which the jaws are pivotally mounted, as well as a rearwardly directed fixed arm associated with each jaw, said drive mechanism comprising a screw spring arranged e.g. around the shaft for opening the jaws and a wedge arranged between the legs for driving inwardly be- tween the arms on the jaws and closing these by means of e.g. at least one pneumatic or hydraulic drive cylinder.

3. A mould device according to claim 1 or 2, c h a ¬ r a c t e r i z e d in that the wedge for closing the jaws has a tongue at each end, and that each of the legs of the fork has a horizontally extending groove comple- mentary to the tongue.

4. A mould device according to claim 1, 2 or 3, c h a ¬ r a c t e r i z e d in that the fork of the gripper is arranged on a common vertical beam, which can be recipro¬ cated horizontally by means of e.g. at least one pneumatic or hydraulic drive cylinder in a parallel guide and move the grippers to the casting position and out of the path described by the steps during demoulding, respectively.

5. A mould device according to claim 1, 2 or 3, c h a ¬ r a c t e r i z e d in that each of the forks of the grippers is carried by at least one separate rod, which can be reciprocated by means of e.g. at least one hydrau- lie or pneumatic drive cylinder in a parallel guide and move the gripper to a position located outside the core or the casting position and out of the path described by the steps during demoulding, respectively.

6. A mould device according to claim 5, c h a r a c ¬ t e r i z e d in that the parallel guide for the rod consists of an outer pipe secured in the interior of the core and having e.g. a circular cross-section, that the rod for carrying the fork of the gripper consists of an inner pipe which is slidably arranged in the outer pipe, and that the drive cylinder for the wedge is provided at the front end of the inner pipe and the drive cylinder for slidably moving the inner pipe at the rear end of said inner pipe.

7. A mould device according to claim 5 or 6, c h a ¬ r a c t e r i z e d in that an intermediate pipe is pro¬ vided between the inner and outer pipes, said intermediate pipe being reciprocatable in the outer pipe by means of a drive cylinder provided in the intermediate pipe, said inner pipe being reciprocatable in the intermediate pipe by means of the drive cylinder provided at the rear end of said inner pipe.

8. A mould device according to one or more of claims 1-7, c h a r a c t e r i z e d in that the means for closing the vertical cut-out in the core for the free passage of the steps during demoulding consist of a laterally hinged door, which can be opened and closed by means of e.g. a pneumatic or hydraulic drive cylinder, and which has an introduction opening for each step.

9. A mould device according to one or more of claims 1-8, c h a r a c t e r i z e d in that the introduction ope¬ ning for each step is defined by the edges in a horizontal cut in the free side of the door facing oppositely to the hinge and an edge in the vertical cut-out of the core when the door is closed, that the outer end of the gripper with closed jaws has a shape complementary to the introduction opening thus formed, and that the rest of the gripper has a height which is equal to or smaller than the height of the cut.

10. A mould device according to one or more of claims 1-9, c h a r a c t e r i z e d in that the upper and lower edges in each of the cuts of the door extend past the gripper when the gripper is in the casting position and the door is closed.

11. A mould device according to one or more of claims 1- 10, c h a r a c t e r i z e d in that the edges in the cuts of the door are bevelled with faces forming an acute angle with the inner side of the door and that the outer end of the gripper is provided with corresponding faces.

12. A mould device according to one or more of claims 1- 11, c h a r a c t e r i z e d in that the free edge of the door facing oppositely to the hinge is bevelled with a face forming an acute angle with the inner side of the door, and that the corresponding edge in the vertical cut¬ out of the core is bevelled with a face forming a corres- pondingly acute angle with the outer side of the core.

13. A mould device according to one or more of claims 1-

12, c h a r a c t e r i z e d in that it comprises a locking means, e.g. a barrel bolt, for locking the door from within during casting.

14. A mould device according to one or more of claims 1-

13, wherein the core is upwardly closed by a firm cover, c h a r a c t e r i z e d in that the vertical cut-out in the core continues in a horizontal cut-out in the cover for the free passage of the steps when the cast article is displaced with respect to the core during demoulding.

15. A mould device according to one or more of claims 1- 14, c h a r a c t e r i z e d in that it comprises a laterally hinged flap which serves to close the horizontal cut-out in the cover during demoulding, and which can be opened and closed by means of e.g. a pneumatic or hydrau¬ lic drive cylinder.

16. A mould device according to one or more of claims 1-

15, c h a r a c t e r i z e d in that it comprises a positioner device located outside the core and having holders for arranging each step in advance in a position from which it can be collected by the gripper.

17. A mould device according to one or more of claims 1-

16, c h a r a c t e r i z e d in that the positioner de¬ vice consists of at least one vertical, rotatable shaft having slots for insertion of the legs of the steps, and that said shaft can be rotated by means of e.g. a rotary cylinder between an angular position in which the slots are in a convenient position for insertion of the steps, and a position from which the inserted steps can be col¬ lected by the gripper.

18. A mould device according to one or more of claims 1- 17, c h a r a c t e r i z e d in that it comprises a magazine located outside the core and having a section opposite each of the step introduction openings of the core, said section being capable of accommodating a stack of steps, and that a pneumatic or hydraulic cylinder is provided for each section to push the lowermost step of the stack inwardly between the open jaws in the respective gripper when the gripper is in the gripping position out- side the core.

AMENDED CLAIMS

[received by the International Bureau on 26 July 1993 (26.07.93); original claim 1 amended; other claims unchanged (1 page)]

1. A mould device for vertically casting tubular articles of concrete or a similar material in one operation, such as well rings or well cones having embedded ladder steps, comprising a hollow core having a wall which has at any rate one upwardly open cut-out for the free passage of the steps when the cast article is displaced with respect to the core during demoulding, said core moreover containing means which are adapted such that they can close the cut¬ out and retain the steps in position during casting and be moved out of the path described by the steps during de¬ moulding, c h a r a c t e r i z e d in that the means for closing the cut-out and retaining the steps during casting comprise at least one door being pivotable by means of a first drive mechanism about a vertical hinge between a position in which the door closes the cut-out, and a position in which the door is displaced from the vertical path described by the steps during demoulding, and having an opening for each of the steps to introduce this step through the wall of the core, and a gripper in form of tongs having jaws which can be moved by means of a second drive mechanism between an open position in which the jaws can gape over a step, and a closed position in which the jaws can clamp the step, the gripper moreover being reciprocatable by means of a third drive mechanism between a casting position where the jaws are in clamping position and at the same time closing the introduction opening in the door, and a demoulding position where the jaws are pulled completely out of the path described by the steps during demoulding, whereby the jaws in the demoulding position are both fully removed from the door.