ITCT20130003A1 - MOBILE MIXING UNIT WITH SUPPORT STRUCTURE SUITABLE FOR ARTICULATED QUADRAT. - Google Patents

Description

â € œMOVABLE MIXING UNIT WITH CLOSABLE SUPPORT STRUCTURE IN ARTICULATED QUADRILATERALâ €

DESCRIPTION

Concrete is a mixture of aggregates, cement, water and any additives, dosed in appropriate proportions and mixed together.

The production of concrete with an industrialized process takes place through the use of concrete mixing plants which essentially consist of:

â € ¢ A set of hoppers (30), which we will call inert groups below, consisting of 1 to n compartments where the aggregates are stored and dosed. â € ¢ A system for loading the dosed aggregates into the mixer which can be carried out by means of a mobile bucket (20) or by means of a conveyor belt (37), in both cases we will define it as an aggregate loading group.

â € ¢ A mixing group consisting of the mixer (2), its support structure, a water â € cement â € additive dosing and supply system, which we will call the pre-fill group (6).

â € ¢ Cement storage silos (32) and tubular augers (33) for transferring the same to the dosing scale (6).

Once the aggregates have been dosed in the appropriate proportions, they are loaded into the mixer where they are mixed with cement, water and any additives to obtain the concrete. The mixers for the production of concrete are divided into:

a) Double horizontal axis mixer (Fig. 9), equipped with two counter-rotating shafts equipped with arms. The mixing tank has an omega section and has a rectangular overall dimensions in plan.

b) Single axis mixer, equipped with a single axis that carries various spirals. The mixing tank is a cylinder with a horizontal axis and this too has a rectangular shape.

c) Turbinate mixer, equipped with blades placed in rotation inside an annular tank.

d) Planetary mixer (Fig.8), equipped with mixing stars that rotate on themselves while they rotate around the axis of the tank. The tank is cylindrical with a vertical axis and has a circular footprint.

To be able to pour the mixed product into the truck mixers (34) for transport to the points of use, the mixer discharge point must be at a height of approximately 4m from the ground level.

Concrete mixing plants can be divided into fixed and mobile and the distinction between one and the other is a function of the effort required for assembly, and any subsequent disassembly, and the need or not for civil works for their installation.

Mobile systems, often favored for temporary construction sites, must be simple and quick to install, but also to disassemble, therefore they must be composed of the fewest number of separate components to reduce installation times and the use of fewer personnel and lifting means. At the same time, this need must be combined with the ease of transporting the plant using normal trailers in road shape or simple 40-foot ISO maritime containers, also in shape. These mobile batching plants are characterized by being able to assume two different configurations, one compact for transport and one working for normal operation.

Today the modalities for the construction of mobile systems are the most varied but in all cases the following problems have been faced:

1) Overall dimensions and transportability of the system.

2) Need to discharge the mixed product at an altitude of approx. 4 meters.

3) Simplicity and speed of installation and commissioning.

4) Accessibility to all system components for normal maintenance operations.

Considering the previous points we try to list the various solutions currently used and which constitute the known art. In the mixing groups produced up to now, the mixer has been supported by a frame which receives and constrains it both during transport and during the working phase. The presence of these frames or supports increases the elements necessary for the realization of the machine and consequently the overall dimensions. For compaction from the working state to the transport state, the most common solution is to hinge the upper part consisting of the mixer and the cement and water metering unit with the lower part of the frame (Figures 1 - 2 - 3 - 4). With this solution the mixer is transported in an inclined position with respect to the ground. This choice has the drawback that during the transport phase the mixer that is not level can lose oil from the transmission components. Depending on the size and weight of the mixing machine, additional trusses or struts must be used to support the structure (35). These elements often have to be transported separately and assembled after the structure has been lifted. Other technical solutions see the mixing and loading unit as a single block (Fig. 5 - 6) which is hoisted at the front and supported by additional structures (35 - 36). In these solutions, the mixer in the transport configuration travels horizontally, in a first phase of assembly it is tilted and subsequently it is leveled again by means of jacks and hinge systems that hold it up. This solution involves the use of a bulky door structure that supports the mixer and all the equipment it contains, with consequent transport difficulties. Another drawback is the application of heavy support structures (35 - 36) while the whole piece is supported by the crane that hoisted it. All the solutions seen so far provide that the mixer in the working position is at the height suitable for direct discharge into the concrete mixer. Other technical solutions `` keep '' the mixer at a limited height (Fig. 7), to be easily loaded with aggregates and cement, and a conveyor belt (38) downstream of the mixer (2) for loading the concrete onto the vehicles ( 34). However, this solution is only applicable for the production of dry concrete. The transport of fluid concrete with a belt leads to the disadvantage of the segregation of the mixed compounds and the loss of grout.

When the mixer used in the mobile batching plant is a planetary mixer, there is the problem that starting from certain sizes and up, the overall dimensions of the mixer exceed the width available for transport with normal trailers in road shape. or with ISO maritime containers. To date, mobile systems built with the use of large planetary mixers involved the â € œbrutal disassembly of parts of the tank in order to fit the entire system inside the transport dimensions, with consequent loss of time during the installation phases and risk, on site, of incorrect assembly of all parts.

We have previously said that the solution adopted for loading the dosed aggregates into the mixer, both in mobile and stationary batching plants, is the use of a conveyor belt or a mobile bucket (skip). The last solution for loading aggregates leads us to highlight a further problem. The mobile bucket (20) is a tank that moves on guides (41) and is pulled by a system of cables and winch (42). Once loaded, the mobile bucket is hoisted by the winch on top of the castelletto where a hatch at its base opens letting the aggregates slide into the mixing tank. Once the contents have been emptied into the mixer, the mobile bucket descends to accommodate the next load. The unloading times of the aggregates from the bucket to the mixing tank are influenced by the state and type of material used, in fact, it is possible to have reduced unloading times when the aggregate is dry and gravelly, and longer times when it is aggregate is sandy and very humid. For a correct functioning of the entire mixing group it is necessary that the bucket pours the entire contents inside the mixer because if this were not the case, the following problems would arise: 1) The mixture produced with that â € œnâ € cycle will not have the correct composition because part of the aggregates intended for its packaging have not been introduced into the mixer. 2) The bucket that goes down to load for the â € œn + 1â € cycle could load more aggregate into the mixer than that foreseen for the mix since the material dosed for the â € œn + cycle is already in the bucket. 1â € in addition to the one left in the tank from the previous â € œnâ € cycle.

2) The mobile bucket that goes down with some material inside has practically reduced its loading capacity and the aggregates that are loaded into the bucket for the next cycle could overflow out of the bucket causing blockages and plant stops.

Up to now it has not been possible to check the correct unloading of the mobile buckets. Currently the time left to the loading bucket to empty the aggregates it contains is a pre-set and fixed parameter for each loading cycle. By detecting the discharge times required by the system to empty itself in the various conditions, the maximum time is identified. This maximum time is set as a parameter that controls parking in the emptying position in such a way as to allow complete emptying of the loading bucket. This type of system has some drawbacks, two of which are: 1) In the event of favorable conditions for the rapid discharge of the aggregates into the mixer, the time actually required for the bucket to be empty and ready to go down for the next load could be shorter. compared to the set time with the consequence that there is an unnecessary wait in the unloading position and therefore a delay in the cycle. 2) Even if a high time reserved for emptying is set, conditions may arise in which this time is in any case insufficient to allow the completion of the unloading and therefore there is material that remains in the loading bucket with the problems already seen.

The present invention proposes to realize a mobile mixing unit for the production of concrete (Fig. 15) complete with mixing machine (2), aggregate loading unit (20), cement, water and additive dosing units (6) and complete with cabin and control panel (19) which solves the problems highlighted in the known art.

. The mixing group presented here is made up of a 5-element structure. Four of these elements are stably hinged together and form an articulated quadrilateral. The first element is the basic structure (1) which is made up of a frame which forms the support base of the entire unit. Once assembled, this element creates a maneuvering compartment which contains the electrical power and control panel (19) and the lower part of the sliding track (39) of the aggregate loading bucket (20). The lower part of this structure constitutes the ground support base of the entire mixing group. To increase the overall stability of the whole, a rigid and heavy base (18) is inserted between the lower beams of the frame, which can be made of concrete, steel or other non-cementitious materials, with the function of ballasting the whole group to the ground of mixing. The rigidity of this element (18) improves the overall stability of the entire structure, considerably reducing the oscillations generated during the operation of the mixing machine located in the upper part. Another function of this element (18) is to form a large and rigid surface to rest on the ground, considerably reducing the contact pressures to the ground. A connecting rod truss (4) is hinged to this basic element (1) in the lower part (point D Fig. 10 - 11), and in the upper part (point C Fig. 10 - 11) the upper track ( 3) sliding of the loading bucket. The mixer (2) is always hinged to these two elements at points A and B (Fig. 10 and 11). The four elements seen (basic structure and control cabin (1) - connecting rod frame (4) - sliding track (3) - mixer (2)) form an articulated quadrilateral which in figures 10 and 11 is highlighted by points A B C and D. The two rotational movements of the elements (3) and (4) on the component (1) lead to a pure translation movement of the element (2) which is physically constituted by the mixer. What has been achieved is therefore a labile kinematics (in the sense that it has the possibility of movement), where, by keeping element (1) constrained, the mixer (2) is able to pass from a lower to an upper position always remaining parallel to the ground and therefore without danger of spillage of the liquids necessary for operation. Given the four elements that make up the articulated quadrilateral we see a fifth element consisting of a floating frame (5) which is hinged to the lower part of the mixer by means of the hinges (40). This frame has the purpose of locking the quadrilateral in a high position, eliminating the degree of freedom present, once the free end of the frame has been blocked with the pins (22). The application of further pins (23) lead to the addition of a further static constraint of the entire frame. In Figure 14 the shape of the mixing unit is superimposed on the lines that schematize the various elements in Fig. 13. So far we have described with the aid of a simplified diagram the articulated quadrilateral structure and the floating connecting rod that make up the frame carrier of the mixing group. Tables 6 - 7 - 8 show various phases of the transition from the transport configuration to the working configuration of the structure. During the opening movement the floating frame (5) is hinged in the lower part of the mixer (2) but at the other end it is free. The element (5) is guided in the lower part by a system that constrains it to slide along the element (4). An example of this system is shown in Fig. 17 where the projection (14) applied to the frame (5) fits inside the groove (15) made in the lower frame (4). Once inserted inside the beam (4) the floating frame (5) is supported during the entire first lifting phase, preventing it from interfering with the ground below. Figure 18 shows the closed mixing group in transport configuration. Figures 20 and 22 show how during the first lifting phases (or vice versa during the last lowering phases) the frame (5) is supported and guided by the frame (4). The peculiarity of the innovation is the sliding of the component (5) on (4) or vice versa with the system previously described or with other possible modalities. In the final lifting phase, the floating frame (5) hangs on the hinge under the mixer and free to hang vertically (Fig. 16 - 17). During the last lifting phase, the floating frame itself (5) is guided in the correct position by a rod (13) which pushes it into position for the insertion of the locking pins (22). This cap also functions in the closing phase to avoid jamming against the plates of the structure (1) making it difficult to lower the entire structure.

So far we have described the mobility of the structure and the way in which it passes from the transport configuration (Fig. 18 - 42 - 43 - 44 - 45 - 46) to the elevated working position (Fig. . 23 - 24 - 25 - 26). The lifting of the entire structure can therefore be carried out with a single lifting means (crane) since all the elements that make up the load-bearing structure are already linked to each other by means of hinges. Once the implant has been hoisted into the working position as shown in Fig. 23 - 24 it is sufficient to insert a locking pin (22) between the floating frame (5) and the base structure (1). With this simple operation, which can be carried out by the operator directly from the ground and in a limited time, the entire structure is blocked and stabilized. The realization of this articulated structure which in the â € œall closedâ € position is very compact and suitable for being easily loaded inside ISO maritime containers is also possible thanks to the fact that functional elements, such as the mixer and the sliding rail of the loading bucket, also perform structural tasks. In the mixing units belonging to the known art, the mixing machine is treated as a non-structural element which must be supported by a suitable support frame. In the mixing group shown here, the mixing machine is equipped with a self-supporting structure and does not need additional support frames. The mixer is linked to the other support elements (3) (4) and (5) by means of pins and hinges and actively participates in counteracting the loads that are generated in the entire structure. Accessory components such as the inspection walkways (21) or the discharge conveyor (41) are then anchored directly to the mixer. The sliding track of the loading bucket is dimensioned in such a way that not only does it not need additional supports but it itself participates in the stability of the structure, constituting a main component of the frame that supports the mixer.

Once the structure has been fixed in the high working position (Fig. 27), the preloading unit consisting of the cement, water and additive dispensers (6) can slide downwards to connect to the mixer (Fig. 28). The described technique allows a structure that during normal operation has a maximum height considerably higher than 8 m to lower and close, reducing its height to less than 2.5 m to be easily transported. The other drawback already described in the prior art is the width of the mixing group in closed configuration for transport in ISO maritime containers. In the mixing group presented here, the problem was solved by making the mixing tank open on two sides and supporting the open sections of the tank (8) with articulated hinges (9). In the upper part, the inspection hood (7), naturally equipped with hinges for opening, is left in the high position to reduce the overall width of the machine. With the previously described device it is possible to rotate with a simple manual movement and without the need for lifting means the part of the tank that can be opened, having the facility given by a movement guided by hinges. All the elements pass from the transport position to the working position with simple rotations and are fixed with screws or snap hooks. The movement from the transport position can be manual or assisted by servomechanisms such as hydraulic or pneumatic actuators or other types but the nature of the invention does not change, it is possible to position the disassembled components to reduce the overall width without the use of lifting equipment or cumbersome positioning operations. The philosophy used for the broken down parts of the mixing tank have been used for other accessory parts of the entire mixing group. In Fig. 29 there is an axonometric view of the mixing group. The perimeter platforms (21) for accessing the mixer, the second flight of stairs (26) and the intermediate floor (13) are hinged to the structure of the entire mixing unit. To pass from the closed transport position to the working position, the components listed above must simply rotate on the predisposed fixing hinges. This system makes assembly quick by minimizing the pieces that remain loose. Fig. 29 â € “30 and 31 shows the sequence of positioning of the accessories that compact on the sides of the closed mixing unit making it possible to transport them with shaped vehicles or even inside ISO maritime containers.

We now illustrate how in the mixing group presented here, and equipped with a mobile loading bucket (20), a system has been created that controls the effective transfer of the aggregates inside the mixing tank.

The mixing unit has been equipped with a load cell (24) positioned between the support structure of the skip track (43) and the tow ropes (25) near the winch (42). The load cell constantly detects the load applied to the rope and from this it is possible to determine the total weight of the entire loading bucket. By setting as zero the value detected by the load cell when the empty bucket is in the unloading position, the display, or the control, can check when the bucket is in that condition. When the aggregate loading bucket carries out a load, and when full it is raised on the mixer, the load cell will show values above zero. Once in the unloading position and opening the door, the material begins to flow towards the mixer tank, gradually relieving the stress on the ropes and zeroing when completely empty.

This system allows to monitor the correct emptying of the loading bucket and allows to make the emptying times dynamic according to the conditions, optimizing each cycle accordingly. It will be possible to eliminate unnecessary waiting times for emptying and highlight the incomplete transfer of the aggregates inside the mixer, blocking the work cycle and avoiding non-compliant production or clogging and machine stops. The mixing group described here can be coupled to any type of aggregate dosing group (Tab.15 / 15), both for mobile and fixed installations.

Claims (10)

â € œMOVABLE MIXING UNIT WITH CLOSABLE SUPPORT STRUCTURE IN ARTICULATED QUADRILATERALâ € CLAIMS 1. A mobile mixing unit substantially constituted by an articulated quadrilateral structure formed by four distinct elements hinged together (base frame and control cabin (1), mixer (2), track for mobile bucket loading system (3), connecting rod frame (4)). 2. A mobile mixing unit according to the preceding claim and equipped with a floating frame (5) hinged at one end to the mixer (2) and lockable with pins at the other end to the base frame (1) to secure the structure in working position. 3. A mobile mixing unit according to any one of the preceding claims, characterized in that a frame floating at one end is guided during movement by means of guides or tips. 4. A mobile mixing unit according to any one of the preceding claims, characterized in that the mixer (2) does not use an additional support frame but is constrained and hinged directly to the supporting columns and diagonals (3,4 and 5). 5. A mobile mixing unit according to any one of the preceding claims, comprising the group of precharges (6) for dosing cement, water and additives, characterized in that by sliding upwards on a track it allows closing and lowering of the entire quadrilateral structure. 6. A mobile mixing unit according to any one of the preceding claims, characterized in that the preloading unit is constrained with a sliding guide to the skip track, and the movement from the transport to the working configuration is controlled by a mechanical winch system or other type of mechanical actuator. 7. A mobile mixing unit according to any one of the preceding claims, characterized in that in the transport configuration the bellies and the hood of the mixer (8 and 9) are folded open, by means of rotation around fixed pins, in in order to reduce the width of the mixing unit and make assembly and start-up easier. 8. A mobile mixing unit according to any one of the preceding claims, characterized in that the mixing unit also comprises the control cabin containing the automated or manual control panel (6) and the compressor (7). The mixing unit also houses the ladder (8) and the walkway (9) for inspecting the mixer (3) with the relative accessories for fixing to the structure. 9. A mobile mixing unit according to any one of the preceding claims, characterized in that it has at the base a ballast made of concrete (18) or other material which confers stability and rigidity to the entire structure. 10. A mobile mixing unit according to any one of the preceding claims, characterized by the fact that the towing system of the bucket (20) (skip) is equipped with a load cell (24) for checking whether the bucket is empty or not (20).