Method for the production of a prefabricated panel to create circular tanks and a relative mould

Abstract

 The present invention relates to a method for the production of a prefabricated panel (10), with two opposing side edges (12, 14) shaped respectively with a male profile and a female profile that can be joined together, comprising at least:
- an operation for forming said panel (10) to give at least a first side edge (12) a male profile (13) and to give at least a second opposing side edge (14) a female profile (15) that can be joined together; and
- an operation for finishing said side edges (12, 14) to give them dimensional and form tolerances that allow dry joining of adjacent panels to create circular tanks;
characterized in that said forming operation and said finishing operation are carried out in a single step.

Description

[0001] The present invention relates to a method and a mold for the production of prefabricated panels to create circular tanks, such as above ground tanks or the like.

[0002] More in detail, the invention relates to a method and a mold for the production of prefabricated panels in reinforced concrete, shaped so as to be placed side by side to form a basin of substantially circular form.

[0003] The invention also relates to a prefabricated panel obtained by means of the aforesaid production method.

[0004] There are numerous sectors in which there is the need to create tanks, in particular above ground tanks, that can be constructed using prefabricated elements to limit costs and reduce production times.

[0005] The use of tanks of this kind is particularly widespread, for example, in the agricultural sector to store sewage or excrement or in the industrial sector to create purification plants or the like.

[0006] These tanks are generally made by assembling a plurality of panels, which are arranged on a concrete base, placed side by side corresponding to the side edges and clamped by means of steel cables placed around the perimeter of the tank.

[0007] Tanks with this configuration and related panels suitable for their creation, are, for example, described in EP 0425537 and EP 0514583.

[0008] In detail, said panels are generally provided with side edges, shaped respectively with a male profile and a female profile so as to define a sort of dovetail that allows them to be joined when arranged side by side corresponding to the perimeter of the tank.

[0009] A method for the production of a panel structured in this way is described, for example, in EP 0707121.

[0010] This method provides for a first forming step in which a reinforcement is positioned in a mold, concrete is cast and vibrated and, after it has hardened, the panel obtained is removed from the mold.

[0011] The mold is generally shaped so as to give the side edges of the panel the respective male and female profiles, in addition to ribs and passages for housing the cables.

[0012] Normally, however, during casting, the thrust exerted by the concrete on the walls of the mold causes deformations which, although limited, are the source of problems during assembly.

[0013] In fact, with prior art molds the side walls shaped to give the edges the male or female joining profile, are created with box elements made of sheet metal a few millimeters thick stamped and/or bent and welded together.

[0014] For example, an imperfect parallelism between the surfaces of two male and female profiles to be joined can lead to the formation of cracks and/or breakage after installation and tensioning of the steel cables that surround the panels.

[0015] In particular, the noteworthy clamping force transmitted by the cables to the panels means that in the areas not in contact between the side edges of two adjacent panels bending stresses (therefore with a component of tractive force) that cannot be sustained by the concrete are produced.

[0016] The lack of perfect adhesion between said side edges can also cause liquid leakage, if the configuration of the tank provides for dry installation, in other words without further pouring of concrete along the joints between one panel and the next.

[0017] One known solution to the aforesaid problems is the further pouring of concrete or the like between the edges of two adjacent panels which, once solidified, allows the clamping force between adjacent panels to be transferred evenly and guarantees hydraulic tightness.

[0018] However, this leads to an increase in the construction costs and times of the tank.

Another solution to the problem

[0019] Another solution to the problem is known from the patent IT 1306407 by the same applicant, which illustrates a method for producing a panel in which the forming step is followed by a further finishing step using a milling machine in which said male and female profiles are machined to give the component adequate dimensional tolerances for "dry" assembly.

[0020] Although functional, this further process leads to a considerable increase in the production costs and times of the panel.

[0021] In particular, given the form and dimensions of these panels, said process is generally carried out on equipment produced entirely or partly ad hoc for this application, the costs of which must be amortized on the single panels produced.

[0022] Moreover, abrasive tools are used to carry out this finishing process (milling), which are in turn subject to a certain degree of wear after a certain period of time. As this wear leads to a gradual variation in the dimension of the tool, this latter must be replaced with relative frequency, or the purpose of the finishing operation would be gradually nullified as the difference in dimension between a panel machined with a new tool and with a worn tool (which could be installed side by side in the same tank) would be too great.

[0023] In this context, the object of the present invention is to provide a method and a mold for the production of prefabricated panels for creating circular tanks that solve the aforesaid problems of the prior art.

[0024] In particular, an object of the present invention is to provide a method and a mold for the production of prefabricated panels that makes it possible to simplify the steps to produce these panels.

[0025] More in detail, an object of the present invention is to provide a method for the production of panels suitable to create circular tanks that can be assembled "dry", which makes it possible to reduce production times and costs.

[0026] A further object of the present invention is to provide a method for the production of prefabricated panels that makes it possible to reduce the number of tools or machines involved in the production process.

[0027] Another object of the present invention is to provide a mold for the production of prefabricated panels that makes it possible to obtain components with very low dimensional tolerances and which guarantee repeatability of said tolerances on a high number of examples produced.

[0028] These objects are substantially achieved by a method for the production of a prefabricated panel, with two opposing side edges shaped respectively with a male profile and a female profile that can be joined together, comprising at least:

• an operation for forming said panel to give at least a first side edge a male profile and to give at least a second opposing side edge a female profile that can be joined together; and
• an operation for finishing said side edges to give them dimensional and form tolerances that allow the side edges of adjacent panels to be joined to create circular tanks;

characterized in that said forming operation and said finishing operation are carried out in a single step.

[0029] Said single forming and finishing step allows a considerable reduction in production times and costs.

[0030] In detail, this is made possible by the fact that said forming operation and said finishing operation are carried out in a mold comprising at least one pair of side boards corresponding to said opposing side edges, each side board comprising a full beam on which at least one substantially non-deformable forming and finishing surface is obtained.

[0031] Said forming and finishing surfaces of the mold make it possible to produce panels with profiles of the side edges with very low tolerances that allow dry assembly of said panels without further machining operations.

[0032] Further characteristics and advantages of the present invention will become more apparent from the following indicative, and therefore non-limiting, description of an example of a preferred but not exclusive embodiment of a mold and of a prefabricated panel, as illustrated in the accompanying drawings, in which:

• Fig. 1 is a perspective view of a prefabricated panel obtained with the production method according to the invention;
• Fig. 2 is a perspective view of a mold for the production of a prefabricated panel with production method according to the invention;
• Figs. 3a to 3c are sectional views respectively of an empty open mold, of an empty closed mold and of a closed mold containing a finished panel.

[0033] With reference to the accompanying figures, the method of the present invention relates to the production of a reinforced concrete panel 10 used for the construction of circular tanks and in particular of above ground circular tanks.

[0034] Said panel 10 comprises a plate 11 of substantially quadrangular form with at least two opposing side edges shaped respectively with a male and female profile and configured to be joined when several panels are placed side by side to form the side edge of a tank.

[0035] More in detail, the panel 10 is provided with at least a first side edge 12 shaped so as to define a male profile 13 and at least a second side edge 14 shaped so as to define a female profile 15.

[0036] As already mentioned, said profiles 13 and 15 of the side edges are configured to be joined together and for this purpose have a substantially complementary form that makes it possible to create a joining surface when two panels are placed side by side.

[0037] In the example shown in the figure, said male profile 13 comprises a projection 13a with a substantially curvilinear section, while the female profile 15 comprises a groove 15a, also with a substantially curvilinear section.

[0038] Preferably the radius of the groove 15a of the female profile 15 is greater with respect to that of the projection 13a male profile 13 so that the joining surface is constituted only of a portion of the surface of the side edges of the panel. This makes it possible to vary the angular position between two adjacent panels, to allow the creation of tanks of different diameter by varying the position of the joining surface on the side edge.

[0039] According to the invention, the method relates to the production of panels that can be assembled dry, i.e. without further pouring of concrete in the joining area between adjacent panels, before the step of tightening the steel cables that surround the tank.

[0040] As already mentioned, these panels must be provided with male and female profiles of the side edges characterized by dimensional tolerances that allow the panels to be placed side by side without interposing concrete or other materials, but preventing the formation of cracks or fractures during tightening of the cables, hydraulic seal between one panel and the next.

[0041] To guarantee the success of the construction and correct operation of a tank, tolerances of rectilinearity, cylindricity or parallelism not exceeding 1 - 2 tenths of millimeter are permitted, therefore very limited considering that these are concrete components that can reach heights (i.e. length of the side) of up to 8 meters.

[0042] For these reasons the production method of panels 10 thus configured comprises a first forming operation, to give at least the first side edge 12 the male profile 13 and to give at least the second opposing side edge 14 the female profile 15, and a second finishing operation of said side edges to give them the aforesaid dimensional tolerances.

[0043] A characteristic of the production method according to the invention is that of carrying out said forming operation and said finishing operation in a single step of the production process.

[0044] In fact, by carrying out said operations in a single step, it is possible to obtain a finished panel, ready for installation, in a shorter time with respect to those produced with prior art methods.

[0045] Advantageously, due to the characteristics of the mold, said forming and finishing operations can be performed simultaneously in the same mold.

[0046] More in detail, said forming operation and said finishing operation are carried out in a mold 20 that comprises at least one pair of side boards 21, 22 corresponding to said side edges 12, 14 of the panel 10.

[0047] According to the invention, said side boards 21, 22 in turn include beams 23, 24 obtained from a monolithic block of material, on each of which at least one forming and finishing surface 23a, 24a is shaped.

[0048] Contrary to prior art molds, said forming and finishing surfaces 23a, 24a are substantially non-deformable, as the monolithic block, preferably made of steel, is capable of withstanding the hydrostatic thrusts of the concrete in liquid state poured into the mold, or other stresses caused by concrete residues, by differentiated tightening or the like, without deforming.

[0049] As already stated, said beams 23, 24 can be made of steel or of other metal materials with the same mechanical strength.

[0050] According to a preferred variant, the beams 23, 24 can have a substantially quadrilateral section with a face shaped to obtain the forming and finishing surfaces 23a, 24a. The thickness of the beam (intended as extension in the direction of the plane of the panel) is preferably variable between 20 millimeters and 60 millimeters to produce panels up to 8 meters and more in height and 20 - 40 centimeters thick.

[0051] The forming and finishing surfaces 23a, 24a thus make it possible to obtain a male profile 13 and a female profile 15 of the side edges with very limited tolerances, typically less than 2 tenths of millimeter, i.e. compatible with dry assembly of the tanks, without the need for further finishing operations on specific equipment, with all the ensuing disadvantages of cost and time.

[0052] Advantageously, according to the invention, said forming and finishing surfaces on each beam are obtained by removal of material, and in particular by milling.

[0053] Unlike sheet metal bending or stamping, this operation ensures precision of the forming surfaces with tolerances of less than one tenth of millimeter which in turn make it possible to limit the dimensional and form tolerances of the male and female profiles 13, 15 of the side edges within the predetermined values.

[0054] According to a preferred embodiment, said side boards 21 and 22 can comprise a box element 27 on which the beams 23, 24 are connected. Said box element allows the lower surface of the side boards to be increased to facilitate connection of joint means 28 that allow movement of the side boards.

[0055] For example, said box element 27 can comprise a metal sheet 8 millimeters thick, welded on the opposite part of the beam 23, 24 with respect to the part on which the forming surface is obtained.

[0056] Generally, the production method of the panel provides that the forming step also comprises the shaping of at least one face 16 of the panel 10 carried out by means of a base plate 25 of the mold specifically structured to produce a series of ribs or the like.

[0057] Preferably, said base plate 25 can be provided with at least two rebates 26 corresponding to two opposing sides on which the side boards 21, 22 sit when said mold is in the closed position (Figs. 3b, 3c) for forming and finishing of the panel.

[0058] More in particular, the forming surfaces 23a, 24a of the beams 23, 24 rest against said rebates 26 when the side boards are taken from the mold open position (Fig. 3a) to the mold closed position (Fig. 3b), before subsequent filling of the mold with the concrete to form the panel (fig. 3c).

[0059] According to the invention, also the surface of said rebates 26 is preferably obtained by the removal of material, for example by milling.

[0060] This guarantees tolerances of less than one tenth of millimeter on the parallelism between said rebates 26 and between the side boards 21, 22 and therefore on the male and female profiles 13, 15 of the panel obtained.

[0061] The panel thus obtained can be installed dry to create circular tanks, i.e. without interposing other material between one panel and an adjacent panel, as the perfect planarity of the surfaces ensures adequate distribution of compression forces.

[0062] It is clear how the production method of the present invention and the related mold make it possible to obtain a finished prefabricated panel characterized by very limited dimensional tolerances with a process that is simplified compared to the prior art.

[0063] In particular, with the present invention the production process is much faster, does not require a further step consisting of finishing of the male and female profiles of the panel by means of milling or similar machining operations.

[0064] The method of the invention also makes it possible to further reduce the costs of the production plant, as it does not require ad hoc equipment to carry out the milling step and replacement of the various tools.

[0065] A further advantage of the present invention is that of providing a method and a mold that allow the production of panels with very limited and practically constant dimensional tolerances, even in very large production batches.

[0066] The present invention, as described and illustrated, may be subject to various modifications and variants, all of which fall within the scope of the invention; furthermore, all the details may be replaced with other technically equivalent elements.

Claims

1. Method for the production of a prefabricated panel (10), with two opposing side edges (12, 14) shaped respectively with a male profile and a female profile that can be joined together, comprising at least:

- an operation for forming said panel (10) to give at least a first side edge (12) a male profile (13) and to give at least a second opposing side edge (14) a female profile (15) that can be joined together; and

- an operation for finishing said side edges (12, 14) to give them dimensional and form tolerances that allow dry joining of adjacent panels to create circular tanks;

characterized in that said forming operation and said finishing operation are carried out in a single step.

2. Method according to claim 1, characterized in that said forming operation and said finishing operation are carried out in a mold (20) comprising at least one pair of side boards (21, 22) corresponding to said opposing side edges (12, 14), each side board comprising a beam (23, 24) obtained from a monolithic block, on which at least one substantially non-deformable forming and finishing surface (23a, 24a) is shaped by the removal of material.

3. Method according to claim 2, characterized in that said forming operation and said finishing operation are carried out using a mold (20) comprising a base plate (25) provided with at least two rebates (26) corresponding to two opposing sides upon which the two side boards (21, 22) sit when said mold is in the closed position, said rebates (26) being obtained by the removal of material using a machine tool.

4. Method according to any one of claims 2 to 3, characterized in that said forming and finishing surfaces (23a, 24a) extend for the entire length of the beam (23, 24).

5. Mold for the production of a prefabricated panel, with at least two opposing side edges (12, 14) shaped respectively with a male profile (13) and a female profile (15) that can be joined together, comprising at least one base plate (25) configured to shape one face (16) of said panel and at least two side boards (21, 22) that can move from a mold open position to a mold closed position, characterized in that said side boards (21, 22) comprise a beam (23, 24) obtained from a monolithic block on which at least one substantially non-deformable forming and finishing surface (23a, 24a) is obtained.

6. Mold according to claim 5, characterized in that said forming and finishing surface (23a, 24a) on the beam is obtained by the removal of material using a machine tool.

7. Mold according to claim 6 or 7, characterized in that said base plate (25) is provided with at least two rebates (26) corresponding to two opposing sides upon which the two side boards (21, 22) sit when said mold is in the closed position, the surface of said rebates (26) being obtained by the removal of material using a machine tool.

8. Prefabricated panel for creating circular tanks provided with two opposing side edges (12, 14) shaped respectively with a male profile (13) and a female profile (15) that can be joined together, obtained using a production method according to one of the claims from 1 to 4 or using a mold according to one of the claims from 5 to 7.

Drawing