Device For Connecting Two Parts of a Female Form For Producing Bottom Parts of a Shaft From Concrete

The present invention relates to a device for connecting two parts of a negative mould or producing shaft bottom parts from concrete and a negative mould comprising at least two parts which can be interconnected by means of such a device.

Shaft bottom parts form the lower end of a multi-part underground shaft via which a sewer system can be accessed for inspection or maintenance. In this bottom region of the shaft, the side wall of the shaft comprises at least one inlet opening and one outlet opening for admitting or discharging waste water respectively. A channel structure is also formed in the shaft bottom part, said structure interconnecting the inlet and outlet openings. Depending on the number and arrangement of the inlet and outlet openings, the channel structure may have different designs, be branched, have a certain gradient or offer different flow cross-sections.

A shaft bottom part to be manufactured from concrete for a shaft of the above-mentioned type comprises a shaft wall which continues the shaft wall of a shaft part to be arranged above said bottom part, and a bottom portion in which the channel structure is formed. In order to enable shaft bottom parts to be manufactured with different channel structures and different arrangements of inlet and outlet openings with minimal technical outlay, methods and devices are known in the prior art in which the mould for moulding the shaft bottom parts is composed of a basic mould, a negative channel mould and at least one recess core, the basic mould reproducing the shaft wall, the negative channel mould reproducing the channel structure in the bottom region of the shaft bottom part and the at least one recess core reproducing the inlet and/or outlet opening.

Before moulding the concrete, the mould must be made up of the specified elements. Whilst the negative channel mould is in a relatively stable position on a mould core of the basic mould and is thus for the most part held by its own weight, the recess core needs to be fixed to a side surface of the negative channel mould, which is associated with higher outlay, especially as any fixing means must not alter the outer contours of the recess core or the negative channel mould, so that the fixing means are not reproduced in the shaft bottom part. In addition, undesirable seams may arise at the joint region between the recess core and the negative channel mould which affect the quality of the finished shaft bottom part.

Furthermore, with conventional moulds for shaft bottom parts, it is often difficult to release the fixing between the recess core and the negative channel mould in order to unmould the shaft bottom part and extract the recess core from the at least partially set concrete of the shaft bottom part. Destruction of the recess core and/or the negative channel mould is often unavoidable to remove the mould completely.

Against this background, the object of the present invention is to provide a device for connecting two parts of a negative mould for producing shaft bottom parts from concrete, said device being able to interconnect the two parts of the negative mould, e.g. a recess core and a negative channel mould, simply and reliably, and with which this connection can be simply released afterwards in order to unmould the shaft bottom part from the mould. The object of the invention is also to describe a negative mould comprising a first part and a second part and a device for connecting the two parts, which permits simple connection or separation of the two parts.

According to a first aspect of the invention, a device is proposed to achieve this object, said device comprising: a positioning element with a holding portion for holding the first part of the negative mould on the positioning element and with a positioning projection that can be pressed into a second part of the negative mould such that the positioning element and the first part of the negative mould are provisionally held on the second part of the negative mould, and a fixing screw that engages with the first part of the negative mould and can be screwed into the second part of the negative mould in order to press the first part against the second part and to fix it thereto.

According to an important feature of the invention, a positioning element is thus provided which is designed to hold the first part of the negative mould and to be simultaneously affixed to the second part of the negative mould by means of a positioning projection so that the first part of the negative mould can initially be held provisionally on the second part of the negative mould. The first part is then fixed to the second part in its target position and can then be fixed in a stable manner to the second part in a second step by means of the fixing screw. The screwing effect of the fixing screw also enables the two parts of the negative mould to be reliably pressed together so that seams between the parts are closed and a high-quality shaft bottom part can be moulded.

A device according to the invention is particularly suitable for connecting two parts of a negative mould which is formed from foamed plastics material or a material with comparable mechanical properties. The positioning element can then be pressed quickly and simply, and in particular also by hand, into the second part of the negative mould with its positioning projection or affixed to the second part of the negative mould with a few hammer blows. Furthermore, the fixing screw can usually be screwed directly into such materials without pre-drilling so that the entire operation to connect the two parts can be performed quickly and simply.

The positioning element can preferably be held displaceably on the first part of the negative mould so that it can be moved towards or away from the second part of the negative mould. The distance between the first part of the negative mould and the second part of the negative mould, i.e. a gap between the two parts, is thus not dependent on how far the positioning projection has been pressed into the second part of the negative mould. In other words, the positioning projection only needs to be partially pressed in with minimal use of force and the first part of the negative mould can still be fixed provisionally but tightly to the second part of the negative mould in its correct position so that the stable connection to the fixing screw can then be produced.

In a preferred embodiment of the invention, the fixing screw is coupled directly or indirectly to the positioning element so as to transmit forces, such that moving the fixing screw, in particular when screwing in the fixing screw, also leads to force being transmitted to the positioning element. This can thus in particular ensure that, when screwing in the fixing screw, the positioning element is pressed further towards the second part of the negative mould and the positioning projections penetrate further into the second part of the negative mould, such that the connection between the parts of the negative mould is more stable and may also be resistant to rotation, in particular, after screwing in the fixing screw.

In the case of indirect force transmission between the fixing screw and the positioning element, the fixing screw can transmit force onto a further component which in turn passes on this force to the positioning element. This additional component is preferably formed by a sleeve through which the fixing screw is passed, said fixing screw being engaged or able to engage with the sleeve and the sleeve in turn being engaged or able to engage with the positioning element. Such a sleeve permits an evenly distributed transmission of force from the fixing screw onto the positioning element around the screw axis such that the fixing screw is guided in the first part of the negative mould and secured against tilting. In particular, the fixing screw preferably has a stop for positioning on a stop on the sleeve in order to carry the sleeve along when moving towards the second part of the negative mould. By using such stops it is possible to ensure that the fixing screw initially carries the sleeve along in the direction of the second part of the negative mould when the fixing screw has been screwed into the second part of the negative mould by a certain amount and the thread of the fixing screw engages in the second part.

If the device comprises a sleeve of the above-described type, the sleeve may also comprise a stop, in particular in the form of an outer flange, for positioning on a stop on the first part of the negative mould, to carry along the first part of the negative mould when the sleeve is moved towards the second part of the negative mould. Such a stop makes it possible to ensure positive force transmission from the sleeve to the negative mould so that greater forces can be transmitted without damaging the first part of the negative mould, in particular in the case of a negative mould made from foamed plastics material.

The sleeve preferably also has a stop for positioning on a stop of the positioning element, to carry the positioning element along when moving towards the second part of the negative mould. This thus allows a certain tolerance with regard to the penetration depth of the positioning projection of the positioning element in the second part of the negative mould, in that a certain distance remains between the sleeve and the positioning element in the provisionally fixed state. Only when screwing in the fixing screw does the sleeve move closer to the positioning element until the stop of the sleeve comes into contact with the stop of the positioning element and the sleeve presses the positioning element further towards the second part of the negative mould.

In a further embodiment of the present invention, the device not only permits the two parts of the negative mould to be easily and securely fixed to each other, but also makes it easier to remove the first part of the negative mould from the second part of the negative mould or from a shaft bottom part to be unmoulded. To this end, the positioning element may comprise a stop for positioning on a stop of the first part of the negative mould in order to remove the first part of the negative mould from the second part of the negative mould or from a shaft bottom part. If the positioning element is accordingly moved in a direction away from the second part of the negative mould, for example by a suitable tool, the positioning element thus positively transmits this force to the first part of the negative mould, such that even high forces can be securely introduced into the first part of the negative mould without damaging or even destroying said part. Negative moulds made from softer materials, in particular foamed plastics material, can thus also be reliably unmoulded and are available for multiple uses.

The above-described positioning element which facilitates unmoulding of the negative mould, preferably also comprises a coupling means for coupling to a pulling tool, in order to pull the positioning element in a direction away from the second part of the negative mould (or out of the shaft bottom part). A bayonet coupling can be used to ensure a particularly simple and simultaneously secure positive coupling, the coupling means of the positioning element being designed such that a pulling tool is inserted into an opening in the coupling means and rotated by a specific angle until it engages behind a portion of the coupling means. If the pulling tool is then pulled back, it carries the positioning element along with it in the pulling direction so that the first part of the negative mould is removed.

In a structurally particularly simple variant of the device of the first aspect, the positioning element may substantially be formed by a plate provided with the positioning projection. The plate may then comprise a central passage opening through which the fixing screw is passed and outside which, for example, the sleeve may be positioned so as to transmit forces. An outer side portion of the plate may simultaneously be positively positioned on a corresponding contact face of the first part of the negative mould to allow force to be transmitted when removing the first part of the negative mould from the second part of the negative mould or from a shaft bottom part.

According to a second aspect of the present invention, the above-described object is achieved by a negative mould for producing shaft bottom parts from concrete, comprising a first part, a second part and a device in accordance with the first aspect of the invention for connecting the first part to the second part, said first part comprising a passage opening through which the fixing screw is or can be passed. Such a negative mould of the second aspect of the invention may be simply and reliably coupled or separated in the manner described above in conjunction with the first aspect of the invention by initially fixing the two parts to each other provisionally and then interconnecting them by means of the fixing screw In addition, the passage opening in the first part enables the fixing screw to be accessed from a side of the first part facing away from the second part such that it is possible to easily fix or release the first part from outside.

The passage opening in the first part of the negative mould is preferably radially widened at one end facing the second part, the positioning element being inserted appropriately in the radially widened end such that it cannot pass right through the passage opening. At the transition between the radially widened end of the passage opening and the narrower portion of the passage opening, a stop or contact portion for the positioning element is then formed, the positioning element being able to positively come to rest on said stop when removing the first part of the negative mould from the second part of the negative mould or from a shaft bottom part to be unmoulded so that even high forces can be transmitted without damaging the first part of the negative mould. The negative mould of the second aspect of the invention can be reliably unmoulded in this manner.

The effects and advantages illustrated above in conjunction with the first aspect of the invention and with the second aspect of the invention are particularly relevant if the first part of the negative mould is a recess core which reproduces an inlet or outlet opening of the shaft bottom part, and the second part is a negative channel mould which reproduces a channel structure of the shaft bottom part. The recess core and the channel structure usually have to be produced by separate parts as unmoulding would not otherwise be possible for reasons of geometry without destroying the negative mould, with the result that a simple and simultaneously reliable coupling between these parts of the negative mould is of particular interest. In addition, unmoulding the recess cores is often difficult due to their approximately cylindrical shape, as said cores are completely surrounded by concrete.

According to a third aspect, the present invention also provides a method for producing shaft bottom parts from concrete, comprising the following steps: providing a first part of a negative mould with a passage opening, inserting a positioning element comprising a positioning projection in the passage opening, provisionally affixing the first part of the negative mould on a second part of the negative mould by pressing the positioning projection into the second part of the negative mould, introducing a fixing screw into the passage opening, screwing the fixing screw into the second part of the negative mould in order to press the first part against the second part and fix it thereto, and moulding a shaft bottom part on the negative mould. The effects and advantages of this method correspond to those of the above-described first and second aspects of the invention.

In an embodiment of the method of the third aspect according to the invention, the method also comprises a step for unmoulding the shaft bottom part, a force being transmitted to the positioning element by a tool and the positioning element transmitting this force to the first part of the negative mould in order to separate the first part of the negative mould from the second part of the negative mould or from the shaft bottom part.

The invention is explained below in greater detail on the basis of a preferred embodiment and with reference to the accompanying drawings, in which:

FIG. 1 shows a cross-sectional view of a mould for producing shaft bottom parts according to an embodiment of the present invention,

FIG. 2 shows a perspective view of a negative channel mould of the mould shown in FIG. 1,

FIG. 3 shows a plan view of a recess core of the mould illustrated in FIG. 1,

FIG. 4 shows a sectional view of the recess core illustrated in FIG. 3 and a device for connecting the recess core to the negative channel mould according to an embodiment of the present invention,

FIG. 5 shows a perspective sectional view of the components illustrated in FIG. 4,

FIG. 6 shows a side view of a pulling tool for unmoulding the recess core illustrated in FIG. 3, and

FIG. 7 shows a front view of the pulling tool illustrated in FIG. 6.

Embodiments of a mould for producing shaft bottom parts and a device for connecting parts of such a mould are explained below with reference to FIGS. 1 to 5.

A device 10 illustrated in FIG. 1 for producing shaft bottom parts 12 from concrete in a casting process comprises a mantle 14 for moulding an outer wall of the shaft bottom part 12, an inner negative mould 16 for moulding the inner wall and the channel portion of the shaft bottom part 12 and recess cores 18 for moulding the inlets and outlets of the shaft bottom part 12. A shaft bottom part 12 is moulded in the cavity which is formed between the mantle 14 and the inner negative mould 16 or the recess cores 18.

The mantle 14 may comprise a cylindrical wall and be positioned on a base plate 20 on which the inner negative mould 16 is also positioned. The inner negative mould 16 may be composed of a mould core 22 which is positioned on the base plate 20 and a negative channel mould 24 which is placed on the mould core 22, said mould core 22 being able to mould an inner wall, and in particular a cylindrical inner wall, of the shaft bottom part 12 and the negative channel mould 24 being able to mould a channel portion at the base of the shaft bottom part 12 to connect the inlets and outlets.

When producing shaft bottom parts, it is often necessary to produce different types of shaft bottom parts which have substantially the same external dimensions and the same shaft diameter, but have different channel structures which differ with respect to the number of inlets and/or outlets and in the design of the connections between the inlet and outlets (in particular inclination, flow cross-section). It is therefore preferable to follow the concept of producing the mantle 14 and the mould core 22 of the inner negative mould 16 from very robust components which are intended for continuous operation, for example steel, and to manufacture the recess cores 18 and the negative channel mould 24 from materials which are easy to machine and/or are more cost-effective, as these parts need to be individually provided for a required channel structure and thus need to be held available in larger quantities. Styropor, for example, is a potential material for the negative channel mould 24 or the recess cores 18, as is used below to represent a range of other easily machined or cost-effective materials.

The components, negative channel mould 24 or recess core 18, illustrated in FIGS. 2 and 3 may be manufactured from a, for example cylindrical-block-shaped, Styropor blank (not illustrated) using shaping material processing. In particular, the desired geometry or surface shape of an automated milling tool can be milled from the blank, for example by using a robot which is controlled by an electronic control device in accordance with a virtual three-dimensional model of the channel structure or the inlet and outlet openings.

In the embodiment in FIG. 2, the negative channel mould 24 comprises a main channel portion 28 to form a main channel branch of the subsequent channel structure of the shaft bottom part and a secondary channel portion 30 integrally connected to the main channel portion 28 to form a secondary channel branch of the channel structure. In order to reproduce the inlet openings or outlet openings, a recess core 18 should be added to each of the opposite side surfaces 28a, 28b of the main channel portion 28 and to a side surface 30a of the secondary channel portion 30 respectively.

Whilst the negative channel mould 24 can be simply positioned on the mould core 22 when putting together the mould 10 and is thus already held in position by its own weight, in some cases supported by screw connections 32, the recess cores 18 should be fixed to the side surfaces 28a, 28b, 30a in a self-supporting manner. A connecting device 34 according to an embodiment of the present invention is used to fix the recess cores 18 to the negative channel mould 24, this being explained in greater detail below, especially with reference to FIGS. 3 to 5.

In order to use the connecting device 34, a through hole 36 is made in the recess core 18 along a main axis M, which coincides with the cylinder axis or middle axis of the recess core 18 in a substantially cylindrical recess core.

The connecting device 34 comprises a fixing screw 38 which can be inserted in the through-hole 36 and which comprises a thread 40 at one of its ends and a screw head 42 at its other end. The thread 40 is adapted to the material of the negative channel mould 24 and is preferably a thread with a relatively large pitch which can be screwed into a foamed plastics material (Styropor) without pre-drilling. The screw head 42 comprises a tool engagement portion 44, for example a hexagonal head, so that the fixing screw 38 can be screwed in by means of an appropriate tool, in particular by using a hydraulic or electric screwdriver.

The connecting device 34 also comprises a positioning plate 46 which should be arranged at right angles to the main axis M and a central passage opening 48 through which the fixing screw 38 passes. The positioning plate 46 bears at least one positioning projection 50, preferably a plurality of positioning projections distributed evenly around the main axis M (in this case two diametrically opposite positioning projections 50). The positioning projections extend parallel to the main axis M and are rigidly connected to the positioning plate 46 at one end, whilst they have a point 52 at the other end which is designed to penetrate the material of the negative channel mould 24. The positioning plate 46 and the positioning projections 50 can be made from metal or a solid plastics material.

At least one spacer 51 is also arranged on the positioning plate 46, said spacer ensuring that even if the positioning projections 50 are completely inserted into the negative channel mould 24, a specific distance remains between the positioning plate 46 and the side surface 28a, 28b, 30a of the negative channel mould 24, which promotes removal of the positioning plate 46 in order to unmould the recess core 18 in a manner to be described later. Two spacers 51 are provided in the embodiment, each of these spacers forming a widened foot portion of the positioning projections 50.

The through-hole 36 comprises a recess 54 at an end portion facing the negative channel mould 24 such that the through-hole 36 is radially widened at this end compared to an inner portion 56 of the through-hole 36. The positioning plate 46 is inserted in the recess 54 so that the positioning plate 46 is held such that it can be displaced along the main axis M and pushed inside the recess core 18 until an outer side portion 58 of the positioning plate 46 comes to rest at a step 60 between the recess 54 and the inner portion 56 of the passage opening 36.

The connecting device 34 in the embodiment also comprises a sleeve 62 of substantially cylindrical form, the cylindrical axis of which coincides with the main axis M. The fixing screw 38 can be inserted through the sleeve 62. In the embodiment, the fixing screw 38 is held in the sleeve 62 such that it cannot fall out by a shaft portion 38a of the fixing screw 38, which has a smaller diameter than the head portion 42 and the thread 40, being guided appropriately in a narrowed neck portion 62a of the sleeve. The sleeve 62 may be made from plastics material, metal or another suitable material.

A main portion 64 of the sleeve has external dimensions which allow the sleeve 62 to be inserted into the inner portion 56 of the passage opening 36. A peripheral outer flange 66 is connected to an end of the sleeve 62 facing away from the negative channel mould 24 on the main portion 64, said outer flange having dimensions which mean that it cannot be inserted into the inner portion 56 of the passage opening 36. The recess core 18 forms a step 68 at which the outer flange 66 rests positively at the transition to the inner portion 56 of the passage opening 36.

At its end facing the negative channel mould 24, an end face 70 forms a stop for positioning on a side of the central passage opening 48, such that the end face 70 of the sleeve 62 cannot pass right through the positioning plate 46. If desired, however, a centering projection 72 of the sleeve 62 can protrude over the end face 70 in the direction of the negative channel mould 24, said projection having a smaller diameter than the main portion 64 of the sleeve 62 and being able to be inserted into the central passage opening 48 of the positioning plate 46. The centering projection 72 may be tapered, in particular towards its free end, so that the centering projection 42 easily finds the central passage opening 48 when guiding the sleeve 62 onto the positioning plate 46.

Furthermore, as illustrated in the embodiment according to FIGS. 3 and 5, the central passage opening may comprise diametrically opposite recesses 74 with respect to the main axis M, at which the passage opening 48 is radially widened. As the recesses 74 are only provided on part of the circumference of the passage opening 43, the sleeve 62 is also reliably supported at its peripheral end face 70 by the remaining non-recessed side portions of the passage opening 48.

Operation of the connecting device 34 according to the invention or operation of the mould 10 for moulding and unmoulding a shaft bottom part 12 is explained below.

A recess core 18, which is prepared for fixing to the negative channel mould 24 by a connecting device 34 of the type according to the invention, may be equipped with the passage opening 36 by passing a corresponding drilling tool with a diameter corresponding to the inner portion 56 of the passage opening 36 through the recess core 18. Furthermore, the recess 54 with the larger diameter is incorporated on a side of the through-hole 36 facing the negative channel mould 24. In addition, a further recess 76 with a larger diameter than the diameter of the inner portion 56 may be incorporated on the side facing away from the negative channel mould 24 such that the outer flange 66 of the sleeve 62 and the screw head 42 of the fixing screw 38 can also be positioned in a countersunk manner in the recess core 18.

The positioning plate 46 is then inserted into the recess 54 and pushed back until it comes into contact with the step 60. The recess 54 is sufficiently deep that the points 52 of the positioning projections 50 then no longer protrude or only protrude by a minimal amount from the recess 54 such that adjustment of the position of the recess core 18 on the negative channel mould 24 in the first instance is not prevented by the positioning projections 50. The operator or a robot can then apply and precisely position the recess core 18 in the desired position on one of the side surfaces 28b, 30a of the negative channel mould 24.

The sleeve 62, along with the fixing screw 38, is then inserted into and pushed forward in the passage opening 36 from the side facing away from the negative channel mould 24 until the end face 70 of the sleeve 62 comes into contact with the side of the central passage opening 48 of the positioning plate 46. If the sleeve 62 is then pressed further towards the negative channel mould 24, it carries along the positioning plate 46 and the positioning projections are pressed into the material of the negative charm& mould 24. This operation can be performed with minimal force expenditure owing to the pointed positioning projections 50. The sleeve 62 can be pushed forward using hammer blows on one end of the sleeve 62 facing away from the negative channel mould 24.

Movement of the sleeve 62 towards the negative channel mould 24 comes to an end when the outer flange 66 of the sleeve 62 conies into contact with the step 68 of the recess core 18 and/or when the positioning projections 50 are pressed sufficiently far into the negative channel mould 24 that the spacers 51 are in contact with the side surface 28a, 28b, 30a of the negative channel mould 24. The recess core 18 is provisionally applied to or fixed on the negative channel mould 24 no later than this time or at an earlier time (when the positioning projections 50 have only partially penetrated the negative channel mould 24), the outer side portion 58 of the positioning plate forming a holding portion for the recess core 18 so that it no longer needs to be held. However, the recess core 18 is not yet connected to the negative channel mould 24 in a sufficiently stable manner to enable it to withstand the pressure of the concrete to be poured in with the desired reliability.

In order to permanently fix the recess core 18, in the next stage, the fixing screw 33 is pushed forward and brought into contact with the side surface 28a, 28b, 30a of the negative channel mould 24. The fixing screw 38 is then screwed into the material of the negative channel mould 24, the rotary movement being caused by a rotary tool, such as a screwdriver, which engages with the tool engagement portion 34. The thread 40 of the fixing screw 38 then engages in the material of the negative channel mould 24 and pulls the fixing screw 38 further towards the negative channel mould 24 or into the negative channel mould when rotated further.

When screwing in the fixing screw 38, the screw head 42 finally comes to rest on an end face 73 of the sleeve 62 facing away from the negative channel mould 24. If rotation of the fixing screw 38 is continued, the screw head 42 then carries along the sleeve 62 in the direction of the negative channel mould 24. During this operation, the sleeve 62 on the one hand displaces the positioning plate 46 further towards the negative channel mould 24 via its end face 70 so that the positioning projections 50 are pressed even deeper into the material of the negative channel mould 24. At the same time, the recess core 18 is carried along over the outer flange 66 and the step 63 and pressed firmly against the negative channel mould 24.

The mantle 14 can then be placed on the inner negative mould 16 or the mantle 14 can be closed. Finally, concrete can be poured in and a shaft bottom part 12 can be moulded in the mould 10.

Once the concrete has at least partially cured, the shaft bottom part 12 can be unmoulded. The mantle 14 may first be opened and lifted off for this purpose. The recess cores 18 and the negative channel mould 24 then need to be removed from the shaft bottom part 12. To this end, the fixing screw 38 is first unscrewed from the negative channel mould 24 again and removed from the passage opening 36 together with the sleeve 62.

A pulling tool 82 illustrated in FIGS. 6 and 7 can then be inserted in the passage opening 36 to pull back the positioning plate 46. The pulling tool 82 may comprise a shaft 84 with two diametrically opposite radial projections 86 at its front end and a handling portion 88 at its rear end, which permits manual or mechanical rotation and pulling of the pulling tool 32. The pulling tool 82 is inserted through the passage opening 36 until the radial projections 86 pass through the recesses 74 of the central passage opening 48 of the positioning plate 46. The pulling tool is then rotated about the axis of the shaft 84 by around 90° such that the radial projections 86 engage behind the side of the central passage opening 48. During this operation, the spacers 51 guarantee that the positioning plate 46 remains at a sufficient distance from the side surface 28a, 28b, 30a of the negative channel mould 24, even after the positioning projections 50 have been completely pressed into the negative channel mould 24, that the radial projections 86 of the pulling tool 82 are able to engage behind the positioning plate 46, i.e. they can be positioned in the intermediate space between the positioning plate 46 and the side surface 28a, 28b, 30a of the negative channel mould 24.

The positioning plate 48 is then carried away from the negative channel mould 24 by a pulling movement of the puffing tool 82 so that the positioning projections 50 are pulled out of the negative channel mould 24. A further pulling movement of the pulling tool 82 displaces the positioning plate 46 up to the step 60 between the recess 54 and the inner portion 56 of the passage opening 36 such that the positioning plate 46 ultimately lies on the recess core 18. A force exerted on the pulling tool 82 in the pulling direction can then be transmitted directly to the recess core 18 in order to pull the recess core 18 away from the negative channel mould 24 and in particular cut of the shaft bottom part 12. Owing to the relatively large peripheral surface area of the outer side portion 58 of the positioning plate 46 and the peripheral step 60, a high tensile force can also be reliably introduced into the recess core 18 during this operation, without damaging or even destroying the recess core 18. The unmoulded recess core 18 can then also be re-used a number of times.

After unmoulding the recess core 18, the pulling tool 82 can be rotated about the axis of the shaft 84 again such that the radial projections 36 are flush with the recesses 74 of the central passage opening 48, so that the pulling tool 82 can be pulled back out of the positioning plate 46 and out of the passage opening 36, if desired, the positioning plate 46 can then be removed from the recess 54 again.

Device For Connecting Two Parts of a Female Form For Producing Bottom Parts of a Shaft From Concrete

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