Machine and method for improving the condition of the outer surface of a cast concrete prefabricated part

Abstract

The invention relates to a machine (1) for improving the condition of the outer surface (12) of at least one portion (29) of a cast concrete prefabricated part (10), the machine (1) comprising at least one mould (20) for pouring concrete provided with a bottom wall (22), longitudinal walls (24) and transverse walls (26), and a support for surface condition improvement means (100) which are movable relative to the cast concrete prefabricated part (10), characterised in that the surface condition improvement means (100) comprise at least a first tool for mechanically stripping the raw outer surface (12) of the prefabricated part (10) in order to remove excess cast concrete, a second tool for smoothing the stripped surface of the prefabricated part (10), and a third tool for finishing the smoothed surface of the prefabricated part (10).

Description

Description Title of the invention: Machine and method for improving the condition of the external surface of a prefabricated molded concrete part Technical field of the invention

[0001] The present invention relates to a machine and a method for improving the surface condition of a prefabricated concrete part, such as a tunnel segment, before the latter has completely solidified, in order to make this surface smooth and free of excess concrete. Previous technique

[0002] In the field of concrete component manufacturing using a mold, for example in the specific case of tunnel walls and especially tunnel segments, a requirement for precision and quality is essential to ensure that the components fit together correctly and have the smoothest possible surface finish. As a reminder, a tunnel segment is a prefabricated element used in tunnel construction. It is generally curved (longitudinally and often also transversely) and is assembled with other adjacent segments to form a tunnel arch with a more or less pronounced and linear curvature.

[0003] It is extremely common, once the mold is placed horizontally, filled with concrete, and homogenized by vibration (particularly to prevent air bubbles), for the upper surface of the piece, called the extrados in this case, to have a particularly rough surface finish due to the presence of numerous concrete residues protruding from it. However, the manufacture of a voussoir requires very high precision and rigorous quality control to guarantee that the final product meets the required safety and durability standards. Even with very high-quality concrete and effective homogenization, the outer surface still exhibits unacceptable defects.

[0004] Currently, it has already been proposed to smooth this exterior surface manually by workers who most often use a trowel. This solution presents numerous disadvantages, the The main drawback is the cost in terms of personnel and, above all, the time required to achieve a result that is often not very satisfactory. In the context of mass production of large quantities of parts, particularly parts that must be identical, it is impossible to maintain a sufficient production rate and ensure uniformity of surface finish across hundreds or thousands of industrially produced components because this would require far too many resources and numerous checks. This solution is therefore not automatable in a mass production plant. However, the precision of the parts produced is paramount to guarantee that the assembly of the hundreds or thousands of segments that make up the side walls and vault of a tunnel can be carried out quickly and accurately, and that the structure will withstand the test of time.

[0005] The use of paints, plasters, fillers, or surface coatings is possible, but it does not solve all problems of excessive roughness on the exterior surface. Furthermore, the proper use of mold vibration during concrete pouring can help eliminate any air pockets and / or local inconsistencies, but the effect on the exterior surface will not be sufficiently effective. The same applies to acid washing, which is used to remove residual slag, as this slag is generally very fluid and its removal does not necessarily eliminate the surface roughness.

[0006] Attempts have already been made to solve this problem by proposing solutions using, for example, smoothing roller / roller systems or metal profiles handled by workers, or even by specialized machines, but these systems are absolutely not optimized or adapted to different types of external surface shapes of prefabricated parts, and are therefore inefficient in terms of output and quality of finish. Presentation of the invention

[0007] The present invention aims to overcome these drawbacks with a completely innovative, highly automated, and reliable approach. fast (high speed compatible with assembly line manufacturing in a factory) and very efficient in terms of surface finish.

[0008] To this end, according to a first aspect, the present invention relates to a machine for improving the external surface condition of at least a part of a prefabricated molded concrete element, such as a tunnel segment, before drying and solidification of said concrete, comprising at least one concrete casting mold equipped with a bottom wall, longitudinal walls and transverse walls, and a support for surface improvement means which are movable relative to said prefabricated molded concrete element, characterized in that said movable surface improvement means comprise at least, from upstream to downstream along a principal direction of use and relative movement of said surface improvement means with respect to said prefabricated element, - a first stripping tool that nibbles away at the rough outer surface of the prefabricated part to remove excess poured concrete, - a second tool for smoothing the stripped surface of said prefabricated part, and - a third tool for finishing the smoothed surface of said prefabricated part.

[0009] This solution makes it possible to obtain a high-quality surface finish in terms of roughness and homogeneity, quickly, without any human effort, repeatedly and for many types of prefabricated parts (shape, curvature, surface)

[0010] The invention is implemented according to the embodiments and variants set out below, which are to be considered individually or in any technically feasible combination.

[0011] Advantageously, the first nibbling stripping tool comprises at least one cutter including a worm gear having a longitudinal axis of rotation connected to a motor and a helical structure having a peripheral nibbling edge, said longitudinal axis of rotation being substantially parallel to a tangent to the outer surface of the prefabricated part even when said surface external exhibits at least one convex curvature along at least one direction among a longitudinal direction and a transverse direction.

[0012] This solution allows the exterior surface of the prefabricated part to be stripped quickly, efficiently and with a good surface finish.

[0013] Preferably, the first nibbling stripping tool includes a cylinder exerting a pressure force on each worm screw that is constantly substantially perpendicular to the outer surface of the prefabricated part, and a sensor that measures said pressure force in real time in order to adjust it to a determined value, typically between about 2 and 20 kg.

[0014] This solution optimizes the stripping process to obtain an exterior surface that retains its shape and dimensions.

[0015] More specifically, the first nibbling stripping tool also includes an inclinometer that measures and then modifies in real time, if necessary, the inclination of the longitudinal axis of rotation of each worm screw so that it remains permanently parallel to a tangent to the outer surface of the prefabricated part.

[0016] This solution also optimizes the stripping process so that the auger closely follows the initial shape of the outer surface of the prefabricated part, ensuring that there are few or no locally hollowed or domed areas.

[0017] According to a particular embodiment of the present invention, the first nibbling stripping tool further comprises at least one scraper disposed downstream of the screw considered and having a lower scraping edge parallel to said axis of rotation and disposed, in use, at a distance from the upper surface of the prefabricated part less than or equal to the distance between the bottom of the peripheral nibbling edge and said upper surface of the prefabricated part.

[0018] This solution allows for a pre-finishing of the surface and, above all, the removal of concrete residues nibbled away by the first stripping tool in order to prepare the surface before the passage of the second tool.

[0019] In addition, the scraper is articulated on a support around a pivot parallel to the axis of the worm gear by means of a cylinder equipped with a rod being able to move out or in in order to move said scraper from an inactive raised position to an active lowered scraping position, and vice versa.

[0020] Preferably, the first nibbling stripping tool comprises a frame supporting two identical worm screws whose axes of rotation are parallel to each other and rotate in the same direction.

[0021] This solution allows for faster stripping by covering a larger surface area.

[0022] In particular, each worm gear has an opposite thread pitch and can only be used individually.

[0023] This solution allows the first stripping method to be operated in two opposite directions if needed.

[0024] According to a preferred embodiment of the present invention, the second smoothing tool comprises at least one polishing disc rotating around an axis of rotation permanently substantially perpendicular to the outer surface of the prefabricated part.

[0025] This solution enables high-quality and reliable automated polishing.

[0026] Specifically, the second smoothing tool comprises a series of polishing discs whose respective axes of rotation are all arranged in the same plane perpendicular to the outer surface of the prefabricated part.

[0027] This solution optimizes polishing by acting on a larger surface area at once.

[0028] In addition, the second smoothing tool includes a cylinder exerting a pressure force on each polishing disc continuously substantially perpendicular to the outer surface of the prefabricated part and a sensor measuring said pressure force in real time in order to adjust it to a determined value between approximately 2 and 20 kg.

[0029] This solution optimizes polishing force and therefore surface finish quality by minimizing or even preventing the local appearance of concave and / or convex areas.

[0030] According to a particularly interesting aspect of the present invention, a liquid spraying system on the surface of the prefabricated part, such as a water mist, is arranged between the first nibbling stripping tool and the second smoothing tool.

[0031] This solution allows the polished surface to be cleaned by slightly moistening it before the third finishing tool is applied.

[0032] More specifically, the liquid spraying system includes at least one arc-shaped ramp surrounding locally, and remotely, an upstream part of a given polishing disc.

[0033] This solution optimizes spraying in terms of spray location.

[0034] In an alternative embodiment, the liquid spraying system comprises two separate arc-shaped ramps surrounding locally, and remotely, the upstream part of the polishing disc in question, each ramp covering an arc between approximately 45° and 90°.

[0035] According to a particularly interesting feature of the present invention, the third finishing tool comprises at least one rear scraping blade articulated around at least one first transverse pivot axis substantially parallel to the outer surface of the prefabricated part.

[0036] This solution allows for the highest quality finish possible by ensuring that the blade of the finishing tool closely follows the shape of the outer surface of the prefabricated part.

[0037] In particular, the rear scraper blade is mounted at the end of a support arm itself articulated around a second transverse pivot axis parallel to the first transverse pivot axis.

[0038] In addition, the articulated support arm is connected to a cylinder exerting a pressure force on the rear scraper blade continuously substantially perpendicular to the outer surface of the prefabricated part and a linear sensor measuring said pressure force in real time in order to adjust it to a determined value between approximately 2 and 10 kg.

[0039] This solution improves the final surface condition of the exterior surface of the prefabricated part by reducing or even preventing the local appearance of hollowed and / or bulged areas which impair the quality of the finished product once the concrete has dried.

[0040] Advantageously, the rear scraping blade has a transverse dimension greater than or equal to the transverse dimension of the second smoothing tool.

[0041] This solution allows you to scrape the entire area that was previously smoothed and avoids the unwanted presence of residue.

[0042] Preferably, all surface finishing tools are mounted on a rail attached to a frame allowing their translation in at least one longitudinal direction.

[0043] This solution allows all the tools to be moved at once and operated successively in a single movement.

[0044] In particular, all surface finish improvement tools are mounted on a robotic arm attached to the main chassis.

[0045] This solution allows the position of the tools to be adapted to that of the outer surface of the prefabricated part.

[0046] More specifically, the robotic arm is mounted on a supporting structure above the manufacturing mold.

[0047] This solution optimizes the volume occupied by the machine by using a gantry that directly overlooks the prefabricated part.

[0048] According to another feature of the present invention, the machine also includes means for cleaning each surface finishing tool.

[0049] This solution accelerates tool usage and therefore the surface finish improvement process for parts in continuous cycle assembly line manufacturing, because each tool used on a given prefabricated part is clean and ready to be reused on the next part, and so on. Assembly line manufacturing can thus be fully automated without human intervention and therefore faster.

[0050] In addition, the cleaning means include at least one external side washing tank to the manufacturing mold and a means of propelling water into said washing tank.

[0051] According to another aspect of the present invention, the machine further comprises a side tray for collecting excess concrete and an articulated ramp taking a first position for collecting excess concrete removed from the outer surface of the prefabricated part and a second position inclined downwards for dumping said concrete into said collection tray.

[0052] The present invention also relates to a method for improving the condition of the external surface of at least a part of a prefabricated molded concrete component, such as a tunnel segment, before drying and solidification of said concrete, using a machine as described above, consisting of performing: - a first stripping stage by nibbling away at the rough outer surface of the prefabricated part to remove excess poured concrete using a first stripping tool by nibbling, - a second step of smoothing the stripped surface of said prefabricated part using a second smoothing tool, and, - a third finishing step of the smoothed surface of said prefabricated part using a third finishing tool.

[0053] Advantageously, the three steps are carried out on a central area of ​​the prefabricated part covering between approximately 15 and 60% of its surface, preferably between approximately 25% and 40% of its surface. Brief description of the figures

[0054] Other advantages, purposes and features of the present invention will become apparent from the following description, given for explanatory purposes and in no way as a limitation, with reference to the accompanying drawings, in which:

[0055] [Fig. 1] Figure 1 is a perspective view of a machine for improving the condition of the external surface of a prefabricated molded concrete part according to the present invention,

[0056] [Fig. 2] Figure 2 is a perspective view of a set of surface finish improvement tools for the machine shown in Figure 1.

[0057] [Fig. 3] Figure 3 is a front view of Figure 2,

[0058] [Fig. 4] Figure 4 is a top view of Figure 2,

[0059] [Fig. 5] Figure 5 is a side view of Figure 2 in the first position,

[0060] [Fig. 6] Figure 6 is a side view of Figure 2 in second position,

[0061] [Fig. 7] Figure 7 is an exploded perspective view of the entire figure 2,

[0062] [Fig. 8] Figure 8 is a detailed perspective view of a first stripping tool for the assembly shown in Figure 2.

[0063] [Fig. 9] Figure 9 is a perspective view of a variant of Figure 8,

[0064] [Fig. 10] Figure 10 is a detailed perspective view of a scraper of the first tool in a first position,

[0065] [Fig. 11] Figure 11 is a detailed perspective view of the scraper of the first tool in Figure 10 in a second position,

[0066] [Fig. 12] Figure 12 is a detailed perspective view of a second smoothing tool for the entire Figure 2.

[0067] [Fig. 13] Figure 13 is a detailed perspective view of a spray system for the second smoothing tool,

[0068] [Fig. 14] Figure 14 is a detailed perspective view of a third finishing tool of the assembly in Figure 2 in a first position,

[0069] [Fig. 15] Figure 15 is a detailed perspective view of the third finishing tool of Figure 14 in a second position,

[0070] [Fig. 16] Figure 16 is a perspective view of a variant of the machine in Figure 1,

[0071] [Fig. 17] Figure 17 is a perspective view of another variant of the machine in Figure 1,

[0072] [Fig. 18] Figure 18 is a perspective view of a first stage of operation of the machine in Figure 1,

[0073] [Fig. 19] Figure 19 is a perspective view of a second operating stage of the machine shown in Figure 1.

[0074] [Fig. 20] Figure 20 is a perspective view of a third operating stage of the machine shown in Figure 1.

[0075] [Fig. 21] Figure 21 is a perspective view of a fourth operating stage of the machine in Figure 1,

[0076] [Fig. 22] Figure 22 is a perspective view of a machine from Figure 1 equipped with means for cleaning surface finish improvement tools. Description of the implementation methods

[0077] Figure 1 shows a machine 1 for improving the surface finish of the extrados 12 (outer surface) of a precast concrete element 10 cast in a mold 20. More specifically, the element 10 is, in this case, a tunnel segment, and the mold 20 is of a known type and typically comprises at least one bottom wall 22, two longitudinal side walls 24 in the shape of an arc, and two shorter transverse side walls 26. Preferably, the mold 20 also includes two hinged covers (not shown) that can be folded down locally over the side walls 24 and 26, leaving an uncovered central area 29 (defined by the dashed lines, as its size varies depending on the size of the hinged covers) used for filling the mold via an upper hopper.

[0078] The machine 1 according to the present invention comprises an articulated robot arm 2 mounted on a chassis 3 securely fixed to the ground and sliding in this case on a rail 4 extending along the longitudinal walls 22 of the manufacturing mold 20 so as to be able to move means 100 for improving the surface condition before drying and solidification of the poured concrete which are mounted at the free end of said robotic arm 2.

[0079] As a preliminary matter, the present description is given on a non-limiting basis, each characteristic of an embodiment being able to be combined with any other characteristic of any other embodiment.

[0080] It should also be noted from the outset that the figures are not necessarily to scale, without this hindering their understanding.

[0081] Thus, in accordance with general figures 2 to 7, the means 100 for improving surface condition comprise, from upstream to downstream along a principal direction F of use and movement of said means in relation to said prefabricated part 10, a first tool 110 for stripping by nibbling the rough outer surface 12 of the prefabricated part 10 to remove excess unsolidified poured concrete, a second tool 120 for smoothing the stripped outer surface 12, and a third tool 130 for finishing the smoothed outer surface 12.

[0082] As can be seen in more detail in Figures 2 to 8, the first nibbling stripping tool 110 typically comprises a substantially horizontal cutter 111 including a helical worm gear 112 (auger type) provided with a peripheral nibbling edge 113. This worm gear 112 is rotated about an axis XXI by means of a pneumatic motor 114 of a known type, for example with a torque reducer, although an electric motor variant is also possible.

[0083] The nibbling stripping tool 110 also includes an internal cylinder 115 mounted on rollers circulating in two parallel rails so as to be able to exert, by extending or retracting its rod 115a, a pressure force on the worm screw 112 preferably permanently perpendicular to the outer surface 12 of the prefabricated part 10, this force typically being between about 2 kg and 20 kg.

[0084] Finally, the nibbling stripping tool 110 is further equipped with an inclinometer-type means (not shown) to measure, when the surface finish improvement means 100 of the machine 1 are in relative motion with respect to the prefabricated part 10, the inclination of the axis XXI. This inclinometer is also designed to modify this inclination in real time so that it is as parallel as possible (and preferably permanently) to a tangent to said upper surface 12 (the line of contact between said upper surface 12 and the peripheral nibbling edge 113 of the helical screw 112) in order to ensure that the removal of excess concrete is as regular as possible and respects the curvature of the prefabricated part 10.Thus, the peripheral edge 113 of the worm screw 112 permanently follows the shape of the outer surface 12 even when the latter has a convex curvature along at least one direction among a longitudinal direction F and a transverse direction T.

[0085] Figure 9 shows an alternative embodiment in which the first nibbling stripping tool 110 comprises two identical worm screws 112 whose respective axes of rotation XXI and XX2 are parallel to each other. These worm screws 112 each rotate in the same direction about their respective axes, or in opposite directions depending on the desired use of the machine 1, or have opposing thread pitches.

[0086] Thus, it is possible to use the machine 1 in a first direction of use F by rotating only one of the two nibbling worm screws 112, then to use the second nibbling worm screw 112 in an opposite direction of movement of the means 100 for improving surface condition.

[0087] It is also possible to use both worm screws 112 simultaneously, assuming that they rotate in the same direction.

[0088] Figures 10 and 11 illustrate a rotating, movable scraper 116 located downstream of the auger 112, i.e., positioned after the excess concrete has been removed as the surface-improving means 100 move. More specifically, this scraper 116 has a lower scraping edge 117, preferably slightly curved with the same curvature as the upper surface 12 of the precast part 10, and extending generally parallel to the axis of rotation XXI. This lower edge is also positioned, during operation, at a distance from the upper surface 12 of the precast part 10 that is less than or equal to the distance between the peripheral edge of the auger 113 and the upper surface 12 of the precast part 10.

[0089] For this purpose, the scraper 116 is articulated on a support 118 around a pivot 118a parallel to axis XXI by means of a cylinder 119 of a known type, equipped with a rod that can extend or retract to move from a raised inactive position (Figure 10) to a lowered active position, known as the scraping position (Figure 11), and vice versa. The scraper 116 thus performs a first preliminary operation of smoothing the upper surface 12 of the prefabricated part 10 used mainly to remove the excess material nibbled by the worm screw 112.

[0090] Figure 12 illustrates in more detail the second smoothing tool 120 which includes at least one polishing disc 121 of known type (for example a PVC SE disc of diameter 450 mm and thickness 10 mm or a PEHD disc of diameter 450 mm and thickness 15 mm) rotating around an axis of rotation YY kept permanently substantially perpendicular to the outer surface 12 of the prefabricated part 10.

[0091] More specifically, the polishing disc 121 is connected to a known type of electric drive motor 122, although a variant using a pneumatic motor is also possible. The rod 115a of the cylinder 115 allows both the worm gear 112 to be moved closer to / further from the outer surface 12 of the prefabricated part, and also the polishing disc 121, assuming that the first nibbling stripping tool 110 and the second smoothing tool 120 are mounted on the same frame, which can be raised or lowered by means of said cylinder 115. In this case, the rod 115a of the cylinder 115 allows a certain downward vertical pressure to be exerted on the polishing disc 121 so that the latter presses constantly and with a controlled force on the outer surface 12 of the prefabricated part 10.

[0092] For this purpose, a sensor of a known type (not shown) is planned to measure said pressure force in real time in order to adjust it to a determined value between approximately 2 and 20 kg.

[0093] According to an alternative embodiment not shown, the rotating shaft of the electric drive motor 122 can move in and out like a pneumatic cylinder so as to exert downward vertical pressure on the polishing disc 121.

[0094] According to another variant not shown, the second smoothing tool 120 comprises a series of polishing discs 121, for example 3 or 4, mounted in parallel and whose respective axes of rotation YY are all arranged in the same plane perpendicular to the outer surface 12 of the prefabricated part 10. This solution makes it possible to smooth a more large surface area of ​​the prefabricated part 10 at a time, but it is more complex to develop.

[0095] Figure 13 shows in detail a liquid spray system 140 mounted between the first nibbling stripping tool 110 and the second smoothing tool 120, that is, more precisely, upstream of the polishing disc 121. This spray system 140 consists of two curved ramps 141, each covering approximately 90° and slightly spaced apart. Each curved ramp 141 locally surrounds the polishing disc 121, a few centimeters from it, and is provided with spray orifices / nozzles 142 to direct a moist mist downstream of said disc 121 so as to moisten the outer surface 12 of the prefabricated part 10 in order to facilitate polishing.

[0096] Thus, figures 14 and 15 show in more detail said third finishing tool 130 which is arranged at the very end of the means 100 for improving surface condition to obtain the final surface condition of the prefabricated part 10. More specifically, this finishing tool 130 includes a rear scraping blade 131 arranged downstream of the second smoothing tool 120, said blade 131 being mounted in an articulated manner on a support 132.

[0097] For this purpose, the scraper blade 131 is articulated around a first transverse pivot axis 133 substantially parallel to the outer surface 12 of the prefabricated part. The support 132 is itself articulated around a second axis 134 parallel to the first axis 133 and connected to an actuating cylinder 135 which allows the rear scraper blade 131 to move from an inactive raised position (Figure 5) to an active lower position (Figure 6).

[0098] Thus, the actuating cylinder 135 exerts a constant pressure force on the rear scraper blade 131, substantially perpendicular to the outer surface 12 of the prefabricated part 10, and a linear sensor (not shown) measures this pressure force in real time in order to adjust it to a predetermined value between approximately 2 and 10 kg to obtain the smoothest possible surface finish. The rear scraper blade 131 has a transverse dimension L greater than or equal to the transverse dimension of the second smoothing tool, i.e. to the diameter D of the polishing disc 121, so that the finishing is carried out in an optimized manner without omitting any area polished by said polishing disc 121. The articulation 133 allows the scraping blade 131 to best follow the potentially curved (domed) shape of the upper surface 12 of the prefabricated part 10.

[0099] Figure 16 illustrates a variant embodiment of Figures 1 to 15 in which the mobile surface finishing means 100 are attached to a gantry-type support structure 6 securely fixed to the ground, with a longitudinal upper rail 4 from which the robot arm 2 carrying said means 100 is suspended. Thus, the various surface finishing tools overhang the prefabricated part 10 and the mold 20, which reduces the footprint of the machine 1 (optimization of space in an assembly line production plant).

[0100] Figure 17 illustrates another variant of the embodiment in which the robot arm 2 is mounted on a chassis 3 without a longitudinal rail and fixed laterally next to a longitudinal wall 22 of the mold 20, the mobile means 100 for improving surface finish then constituting a kind of three-dimensional mobile head attached to the end of the robot arm 2 so that they can be moved without difficulty over the entire outer surface 12 of the prefabricated part 10.

[0101] In figures 18 to 21, the machine 1 further comprises a container 160 for recovering excess concrete, an articulated plate 161 taking a first substantially horizontal position for recovering the excess concrete evacuated from the outer surface 12 of the prefabricated part 10 (figure 19 then figure 20) at the level of a longitudinal wall 22 of the mold 20, and a second position inclined downwards (figure 21 then 22) for pouring said concrete into said recovery container 160, and a fixed and inclined intermediate ramp 162 connecting said articulated plate 161 to said recovery container 160.

[0102] Figure 22 shows means 170 for cleaning the surface finish improvement means 100. More specifically, these cleaning means 170 typically include a side tray of external washing of the manufacturing mold 20, a water source and a means of water propulsion (for example jets) in said washing tank to remove concrete from the various tools 110, 120 and 130 so that they are clean.

[0103] The operation of machine 1 according to the present invention is as follows:

[0104] Once the liquid concrete has been poured between the different walls of the mold 20 and then homogenized by various known means (for example, direct vibrations of the mold 20 or vibrators inserted into the poured concrete), but before said concrete dries and hardens completely, the machine 1 according to the present invention is used to improve the rough surface condition of the outer surface 12 of the prefabricated part 10.

[0105] Due to the longitudinally curved shape of the mold 20 (or even curved both longitudinally and transversely), the outer surface 12 (extrados) of the prefabricated part 10 has a surface condition (roughness) that is more or less granular (depending on the type of concrete used, its quality and / or its homogeneity), and includes in particular protruding asperities of more or less large size, especially in the central area 29 (where the side covers cannot be folded down), so that the product often cannot be used as is and a finishing (smoothing) must therefore be carried out.

[0106] For this purpose, according to the variant of machine 1 illustrated by figures 1, 16 and 17, the robot arm 2 is brought close to the mold 20 and in particular to the central area 29 of the latter.

[0107] The surface finish improvement means of machine 1 can then be activated according to a well-defined chronological process, starting with the rotation of the milling cutter 111 so that it gradually removes, as the robot arm 2 moves, the largest concrete residues (a few millimeters to a few centimeters) protruding from the outer surface 12 of the prefabricated part 10.

[0108] For this purpose, the pneumatic motor 114 is started to rotate the worm gear 112 around its axis XXI as the arm of Robot 2 moves, and the cylinder 115 adjusts both the stripping pressure exerted by the helical nibbling edge 113 on the concrete and the stripping height (penetration distance of the helical nibbling edge 113 into said concrete). The inclination of the rotation axis XXI can also be managed in real time so that it remains constantly parallel to a virtual tangent line between the nibbling edge 113 and said outer surface 12, in order to best follow the curvature of the prefabricated part and avoid convex areas (insufficient nibbling) or concave areas (excessive nibbling).

[0109] At the beginning of this first step, the second smoothing tool 120 and the third finishing tool 130 are preferably raised and away from the outer surface 12 of the prefabricated part.

[0110] Simultaneously with the nibbling, the scraper 116 is lowered and performs a troweling of the outer surface 12 of the prefabricated part 10 and serves mainly to carry away the concrete residues to prevent them from stagnating on said surface and interfering with the next step.

[0111] The height of the milling and scraping is adjusted on each mold 20 by probing and feedback from robot 2, this information can be stored in a programming / control automation system with management of the reference point of each mold for launching the program adapted to each of them (adapted trajectories).

[0112] From the moment when a sufficient area of ​​the outer surface 12 of the prefabricated part 10 has already been nibbled away by the stripping tool 110, the polishing disc 121 is then lowered using the cylinder 115 to come into contact with said outer surface 12 from which the most important concrete residues have normally already been removed during the previous step.

[0113] The polishing disc 121 is then set in rotation (if this was not the case before its descent) around its axis YY thanks to the electric motor 122, and the robot arm 2 continues its longitudinal advance movements and then transverse displacement so that the central portion 29 of the outer surface 12, cleared of the largest concrete residues, is troweled little by little.

[0114] The pressure exerted by the cylinder 115 on the polishing disc 121 is controllable and can be adjusted according to the consistency of the concrete, this force being parameterized in real time or chosen in advance from a control panel by an operator making, for example, a choice according to the quality of the concrete and / or the desired troweling.

[0115] The curved spray arms 141 of the spraying system 140 are also activated before or at the moment the polishing disc 121 comes into contact with the outer surface 12 of the precast part 10 in order to facilitate troweling by wetting the stripped concrete. The misting system is preferably controlled from a control panel, with the quantity of water and the misting area being determined in advance or in real time depending on the quality of the concrete.

[0116] Once a sufficient area of ​​the outer surface 12 of the prefabricated part 10 has been troweled by the polishing disc 121 of the second smoothing tool 120, the third finishing tool 130 is then activated.

[0117] More specifically, the scraper blade 131 is pivoted around its second axis of rotation 134, and pressure is applied to it by means of the actuating cylinder 135. This pressure then allows the scraper blade 131, as the robot arm 2 continues its movement, to refine the surface finish by smoothing the surface previously smoothed by the polishing disc 121, thus making the outer surface 12 of the prefabricated part as smooth and homogeneous as possible. The pressure exerted by the actuating cylinder 135 and the height of the scraper blade 131 are continuously measured and adjusted to optimize this finishing operation according to the quality of the concrete and the desired smoothness.

[0118] According to an alternative embodiment optimizing the process of improving the surface condition of the prefabricated part 10, the use of the second smoothing tool 120 and then the third finishing tool 130 can be triggered only after all the excess concrete has been removed from the central area 29 of the mold 20.

[0119] It should be noted in passing that the central zone 29 covers between approximately 10 and 50% of the external surface of the prefabricated part 10 and preferably between approximately 15% and 30% of said surface.

[0120] To this end, figures 18 to 21 successively illustrate this intermediate step during which the scraper 116 brings, at the end of the stripping step by nibbling, all of the excess concrete towards the plate 161 which then tilts to pour it into the recovery tray 160 via the inclined ramp 162.

[0121] Once the stripping, smoothing, and finishing operations have been completed, the various tools carried by the robot arm 2 can be automatically washed using the cleaning tank 170 provided for this purpose (hot water spray from high-pressure nozzles, with a recovery and recycling system). A new surface finishing cycle can then begin on the outer surface 12 of another prefabricated part 10, and so on in the case of automated assembly line production. To minimize weight, most of the tools are made of aluminum, a material that requires no special treatment when used for washing with water.

[0122] Machine 1 according to the present invention has many advantages including automation reducing or even eliminating the need for human presence (except for monitoring and maintenance of the machine), high production rate, repeatability, quality and homogeneity of the surface finish obtained from the prefabricated parts.

[0123] The complete straightening time is approximately 48 seconds per meter. 2 The rotational speed of the milling cutter 111 is approximately 300 rpm when unloaded and between approximately 150 and 200 rpm when in use, primarily depending on the penetration depth of the auger 112 (thickness of the concrete being chipped) and / or the type of concrete. The rotational speed of the polishing disc 121 is approximately 500 rpm when unloaded and between approximately 250 and 300 rpm when in use, primarily depending on the concrete quality and / or the desired trowel finish.

[0124] It must be clearly understood that the detailed description of the object of the invention, given solely by way of illustration, does not constitute in in no way a limitation, technical equivalents also being included within the scope of the present invention.

[0125] Thus, the number of worm gears can vary, as can the number of scrapers, smoothing discs or scraping blades.

[0126] This machine could be used for the manufacture of concrete walls or any concrete surface requiring troweling and then a finishing smoothing.

[0127] Spring or gas spring systems, instead of pneumatic cylinders, are conceivable for exerting the pressure forces mentioned above.

Claims

Demands Claim 1. A machine (1) for improving the external surface condition (12) of at least a portion (29) of a precast molded concrete element (10), such as a tunnel segment, before the concrete dries and solidifies, comprising at least one concrete casting mold (20) having a bottom wall (22), longitudinal walls (24) and transverse walls (26), and a support (2; 3) for surface improvement means (100) that are movable relative to said precast molded concrete element (10), said movable surface improvement means (100) comprising at least, from upstream to downstream along a principal direction (F) of use and relative movement of said surface improvement means (100) with respect to said precast element (10): - a first stripping tool (110) for nibbling away at the rough outer surface (12) of the prefabricated part (10) to remove excess poured concrete, - a second (120) tool for smoothing the stripped surface of said prefabricated part (10), and - a third tool (130) for finishing the smoothed surface of said prefabricated part (10), characterized in that - the first nibbling stripping tool (110) comprises at least one cutter (111) including a worm screw (112) having a longitudinal axis of rotation (XXI) connected to a motor (114) and a helical structure having a peripheral nibbling edge (113), said longitudinal axis of rotation (XXI) being substantially parallel to a tangent to the outer surface (12) of the prefabricated part (10) even when said outer surface has at least one convex curvature along at least one direction among a longitudinal direction (F) and a transverse direction (T), - the second smoothing tool (120) comprises at least one polishing disc (121) rotating about an axis of rotation (YY) permanently substantially perpendicular to the outer surface (12) of the prefabricated part (10), and - the third finishing tool (130) includes at least one rear blade of scraping (131) articulated around at least one first transverse pivot axis (133) substantially parallel to the outer surface (12) of the prefabricated part (10). Claim 2. Machine (1) according to claim 1, characterized in that the first nibbling stripping tool (110) comprises a cylinder (115) exerting on each worm screw (112) a pressure force permanently substantially perpendicular to the outer surface (12) of the prefabricated part (10) and a sensor measuring said pressure force in real time in order to adjust it to a determined value, typically between about 2 and 20 kg. Claim 3. Machine (1) according to claim 2, characterized in that the first nibbling stripping tool (110) also includes an inclinometer measuring and then modifying in real time if necessary the inclination of the longitudinal axis of rotation (XXI) of each worm screw (112) so that it remains permanently parallel to a tangent to the outer surface (112) of the prefabricated part (10). Claim 4. Machine (1) according to any one of the preceding claims, characterized in that the first nibbling stripping tool (110) further comprises at least one scraper (116) disposed downstream of the screw (112) considered and having a lower scraping edge (117) parallel to said axis of rotation (XXI) and disposed, in use, at a distance from the upper surface (12) of the prefabricated part (10) less than or equal to the distance between the bottom of the peripheral nibbling edge (113) and said upper surface (12) of the prefabricated part (10). Claim 5. Machine (1) according to claim 4, characterized in that the scraper (116) is articulated on a support (118) around a pivot (118a) parallel to the axis XXI by means of a cylinder (119) provided with a rod that can extend or retract in order to move said scraper (116) from an inactive raised position to an active lowered scraping position, and vice versa. Claim 6. Machine (1) according to any one of the preceding claims, characterized in that the first nibbling stripping tool (110) comprises a frame supporting two identical worm screws (112) whose axes of rotation (XXI; XX2) are parallel to each other and rotate in the same direction. Claim 7. Machine according to claim 6, characterized in that each worm screw (112) has an opposite screw pitch and is usable only individually. Claim 8. Machine (1) according to any one of the preceding claims, characterized in that the second smoothing tool (120) comprises a series of polishing discs (121) whose respective axes of rotation (YY) are all arranged in the same plane perpendicular to the outer surface (12) of the prefabricated part (10). Claim 9. Machine (1) according to any one of the preceding claims, characterized in that the second smoothing tool (120) comprises a cylinder (115) exerting on each polishing disc (121) a pressure force permanently substantially perpendicular to the outer surface (12) of the prefabricated part (10) and a sensor measuring said pressure force in real time in order to adjust it to a determined value between approximately 2 and 20 kg. Claim 10. Machine (1) according to any one of the preceding claims, characterized in that a liquid spraying system (140) on the outer surface (12) of the prefabricated part (10), such as a water mist, is arranged between the first nibbling stripping tool (110) and the second smoothing tool (120). Claim 11. Machine (1) according to claim 10, characterized in that the liquid spraying system (140) comprises at least one arc-shaped ramp (141) surrounding locally, and remotely, an upstream part of a polishing disc (121) considered. Claim 12. Machine (1) according to claim 11, characterized in that the liquid spraying system (140) comprises two separate arc-shaped ramps (141) surrounding locally, and remotely, the upstream part of the polishing disc (121) considered, each ramp covering an arc between approximately 45° and 90°. Claim 13. Machine (1) according to any one of the preceding claims, characterized in that the rear scraper blade (131) is mounted at the end of a support arm (132) itself articulated around a second transverse pivot axis (134) parallel to the first transverse pivot axis (133). Claim 14. Machine (1) according to claim 13, characterized in that the articulated support arm (132) is connected to a cylinder (135) exerting on the rear scraper blade (131) a pressure force permanently substantially perpendicular to the outer surface (12) of the prefabricated part (10) and a linear sensor measuring said pressure force in real time in order to adjust it to a determined value between approximately 2 and 10 kg. Claim 15. Machine (1) according to any one of the preceding claims, characterized in that the rear scraping blade (131) has a transverse dimension greater than (L) or equal to the transverse dimension (D) of the second smoothing tool (120). Claim 16. Machine (1) according to any one of the preceding claims, characterized in that all the surface finish improvement tools (110, 120, 130) are mounted on a rail (4) attached to a frame (3) allowing their translation in at least one longitudinal direction (F). Claim 17. Machine (1) according to claim 16, characterized in that all the surface finish improvement tools (110, 120, 130) are mounted on a robotic arm (2) attached to the main frame (3). Claim 18. Machine (1) according to claim 17, characterized in that the robotic arm (2) is mounted on a supporting structure (6) overhanging the manufacturing mold (20). Claim 19. Machine (1) according to any one of the preceding claims, characterized in that it further comprises means (170) for cleaning each tool (110, 120, 130) for improving surface condition. Claim 20. Machine (1) according to claim 19, characterized in that the cleaning means (170) comprise at least one washing tank (172) external to the manufacturing mold and a means of propelling water into said washing tank (172). Claim 21. Machine (1) according to any one of the preceding claims, characterized in that it further comprises a side tray (160) for recovering excess concrete and an articulated ramp (161) taking a first position for recovering the evacuated excess concrete of the outer surface (12) of the prefabricated part (10) and a second downward inclined position for pouring said concrete into said recovery tank (160). Claim 22. A method for improving the condition of the outer surface (12) of at least a portion (29) of a prefabricated molded concrete component (10), such as a tunnel segment, before drying and solidification of said concrete, using a machine (1) according to any one of the preceding claims, consisting of performing: - a first stripping step by nibbling the rough outer surface (12) of the prefabricated part (10) to remove excess poured concrete using a first stripping tool (110) comprising at least one cutter (111) including a worm screw (112) having a longitudinal axis of rotation (XXI) connected to a motor (114) and a helical structure having a peripheral nibbling edge (113), said longitudinal axis of rotation (XXI) being substantially parallel to a tangent to the outer surface (12) of the prefabricated part (10) even when said outer surface has at least one convex curvature along at least one direction among a longitudinal direction (F) and a transverse direction (T), - a second smoothing step of the pickled surface of said prefabricated part (10) using a second smoothing tool (120) comprising at least one polishing disc (121) rotating around an axis of rotation (YY) permanently substantially perpendicular to the outer surface (12) of the prefabricated part (10), and, - a third finishing step of the smoothed surface of said prefabricated part (10) using a third finishing tool (130) comprising at least one rear scraping blade (131) articulated around at least one first transverse pivot axis (133) substantially parallel to the outer surface (12) of the prefabricated part (10). Claim 23. Method according to claim 22, characterized in that the three steps are carried out on a central area (29) of the prefabricated part (10) covering between about 10 and 50% of its surface, preferably between about 15% and 30% of its surface.

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