Patent ID: 12186936

DETAILED DESCRIPTION OF THE INVENTION

There follows below a detailed description of a preferred embodiment of the present invention, by way of example and in no way limiting. Nevertheless, it will be clear to one skilled in the art, from reading this description, possible further embodiments of the present invention still comprised by the essential and optional features below.

FIG.1schematically illustrates the devices that make up the demolding system for materials manufactured by freeze-casting. In a simplified way, the demolding apparatus consists of a source of compressed air (1), a pressure regulator filter (2) coupled with a manometer (3), a pneumatic directional valve (4), a linear actuator (5), a baton (6), a flow regulating valve (7), a fastening means (8), a metallic support (9) and a chamber for receiving the cooled material (10).

The linear actuator (5) is a device capable of providing movements in a linear trajectory, so it can be applied in situations that require the action of tilting, lifting, pulling or pushing a load. The linear actuator used in this assembly, according to the perspective illustrated inFIG.2a, is pneumatic in nature and is not limited to this operating principle, allowing, for example, the use of mechanical, hydraulic or electromechanical devices. The linear actuator, according to the AA section shown inFIG.2b, can consist of two heads, one front (17) and one rear (18) and four tie rods (19) that provide support to the set. In the heads, there are holes (20) that allow the connection of a hose to carried compressed air and access to the upper (21) and lower (22) chambers. Compressed air filling in the chambers promotes the upward and downward movement of the piston (23). The sealing is done by positioning a set of sealing rings (25) on the piston. The metal rod (24) is coupled to the piston and, in a similar way, moves as a function of the accumulation/emptying of pressurized air in the chambers. A fastened support for the moving rod is provided by a bearing (26), which is positioned at the outlet of the lower chamber. The entire system is surrounded by a skirt (27) of anodized aluminum, not limited to this material, to provide protection to the operating system in general.

In this apparatus, the compressor (1) converts energy, with the aid of a motor, into stored potential energy (pressurized air). When released from the compressor, the compressed air is sent to a pneumatic pressure regulating filter (2) coupled with a manometer (3). The pressure regulator filter (2) is provided with a valve that opens and closes in order to regulate the outlet pressure. With the aid of the manometer (3) it is possible to check the pressure of the compressed air being fed into the pneumatic directional valve (4). The pneumatic directional valve can be optionally a 5/2-way model, not limited. The 5/2-way valve has five ports, one for inlet (14), two for exhaust (13) and two for work (15). An actuator for intervention in the advance or withdrawal of the piston (23) is installed in the directional valve, optionally being allowed the use of a driving button with lock (11). When compressed air is allowed to enter the linear actuator, the upper chamber (21) of the cylinder is filled, thus generating a pressure difference between the interior of the upper chamber and atmospheric pressure, promoting energy accumulation. The filling of the upper chamber forces the wall of the piston (23), causing it to move, causing the axial movement of the metal rod (24). After the displacement, the piston remains immobile in that position until it receives an external stimulus. The (optional) use of a linear actuator with double-acting capability allows the filling of the lower chamber (22), returning the piston to the initial position by expelling the air trapped in the upper chamber through the exhaust ports (13) of the directional valve (4). Optionally, the installation of pneumatic filters (12) is foreseen in the exhaust ports to attenuate the sound produced by the exit of air and prevent the entry of solid impurities. A flow regulating valve (7) is connected to the outlet of the lower chamber, responsible for controlling the flow rate of exiting confined air (emptying) in the lower chamber, managing the downward displacement of the piston over time. At the top of the regulator, there is a handle (16) which, when turned, determines the size of the section of the passage hole of the pressurized air. In other words, this adjustment in the outlet flow is responsible for adjusting the speed of movement of the internal metallic rod of the linear actuator. At the end of the rod that is external to the skirt, a thread is provided, which allows the connection of a baton (6), preferably made of an insulating material such as polyamide, not being limited to this material, which during the movement of the piston will be forced to be inserted into the metallic mold, expelling the material obtained by the freeze-casting process to the receiving chamber.

The support of the pneumatic linear actuator is obtained by installing it on a support (9) produced with high mechanical strength metallic material, preferably in carbon steel, without being limited. The schematic drawing inFIG.3aillustrates an optional design for the metal support. InFIG.3ba top view of the support is shown and inFIG.3ca side view as shown in section BB shown inFIG.3a. The metallic support has a structure that comprises an upper base (28) for positioning the linear actuator, an intermediate platform (29) for positioning the metallic mold, a foundation (35) for stabilizing the set on a flat surface and pillars that support the apparatus. In order to conduct the fastening of the linear actuator on the upper base of the metallic support, a fastening means (8) is used, optionally a front fastening flange, compatible with the cylinder dimensioned for the application according to the assembly shown inFIG.4b. Therefore, holes (33) are provided in the upper base to aid in fastening the flange by means of screws (not identified). In a similar way, the linear actuator is fastened to the flange, according to the illustration shown inFIG.4a. The middle platform must provide a central hole (30) for the passage of the lower part of the metallic mold. In addition, there must be an arc-shaped edge (31) that allows fastening the side flap of the mold. Similarly, there must be a frontal cut (32) that allows the mold access to the edge fitting point and consequent fastening of the mold support ring, as emphasized byFIG.3b. For that, the metallic mold must have a ring perpendicular to its length that, when being driven to the positioning in the set of the intermediate base of the support, will promote its immobilization during the introduction of the demolding piston. It is worth to emphasize the importance of the juxtaposition between the side ring of the mold and the edge of the intermediate platform (29) of the support, a device constituted by a material of low thermal conductivity (34), in order to delay the transfer of heat between the metallic components, curbing the heat conduction from the metal support to the cooled mold.

For the production of materials by means of the freeze-casting technique, an apparatus is used as described inFIG.6. This assembly basically consists of the use of an open metallic tubular mold (36), sealed by two metallic covers, upper (37) and lower (38), and an inner tube mold (39) produced with material of low thermal conductivity. The metallic mold must be manufactured in such a way as to have an external central ring (40) that will support the metallic support. The importance of this ring lies in the fact that its function is to keep the metallic component immobile during the application of pressure by means of the baton inside, promoting the sliding of the material produced by freeze-casting, as shown inFIG.5b. The internal mold is made to be a completely solid piece that will be centered inside the metallic tube with the help of the upper and lower sealing covers. After positioning the lower cover and the internal mold in the metal tube, the suspension (41) is poured into the cavity between the two elements, as shown inFIG.7b. Next, the assembly is sealed with the top metal cover. The artifact is immersed in a bath containing the coolant. When the liquid comes into contact with the external face of the metallic tube, a rapid cooling of the molding component occurs and this loss of heat is transmitted to the suspension. However, the internal mold remains at a temperature close to room temperature. The temperature gradient allows the growth of solvent crystals in the radial direction, that is, from the external metallic mold to the insulating internal mold. This assembly is valid for obtaining materials with pore structures ordered in the geometry of hollow tubes or cylinders and discs, dispensing with the use of the polymeric baton or by means of changes in the configuration of the molding devices. At the end of cooling, the suspension (41) will have turned into a solid (42).

To conduct the demolding, firstly, the upper (37) and lower (38) metal mold covers must be removed, as well as the internal polymeric baton (39). Next, the metallic mold together with the frozen sample is positioned on the intermediate platform (29) of the metallic support, as can be seen inFIG.5a. The polymeric baton, under the action of the linear actuator, is introduced inside the mold and comes into contact with the upper face of the material, as shown inFIG.8a. The baton continues to exert a force directed downwards and promotes the sliding of the part as it advances inside the mold, as shown inFIG.8b. The advance speed of the baton must be efficient to the point of not allowing the heating of the metallic assembly and/or cooled solid, thus guaranteeing that the produced material will not be damaged. The device mechanism must also act in order to avoid structural damage that could occur by strong impacts after its complete expulsion from the mold. After ejection, the porous material produced is directly directed to a temperature-controlled receiving chamber to receive the material and maintain its structural integrity.

The linear actuator used in this assembly is pneumatic in nature, not being limited to this operating principle, being admitted, for example, the use of mechanical, hydraulic or electromechanical devices. The genre must be determined according to the application for which it is intended for and, thus, the necessary adjustments must be made to adapt to the system. The linear actuator can be of double acting or single acting type.

The entire linear actuator system is surrounded by a skirt, which can be made of anodized aluminum or any other material, provided that it protects the operating system in general, such as against impacts, corrosion, impurities between others.

The tubes that make up the compressed air circulation circuit from the compressor to the pneumatic actuator must have sufficient flexibility and mechanical strength characteristics for the intended application. These hoses can be optionally manufactured from materials such as polyurethane, polyamide or others.

The pneumatic directional valve is not limited to the 5/2-way model, and can be replaced by any other that guarantees the function of commanding the start, stop, adjustment and change of the direction of the compressed air according to the needs of each application.

The metallic support must be made up of a material of high mechanical strength and chemical resistance, and carbon steel, stainless steel, brass or similar can be used.

The proposed device enables the demolding of materials in different formats such as: discs, cylinders, billets, bars or hollow tubes in different dimensions. Other formats can be used unless adjustments are made in the design of the general system, including the metal support, the ejection baton and others.

The ejection baton must preferably be made of an insulating material, for example polyamide, which sufficiently delays the heat transfer to the material produced to avoid damage to the pore structure.

Between the side ring of the mold and the edge of the intermediate platform (29) of the support, a device can be positioned, optionally a ring, consisting of a material of low thermal conductivity, for example, rubber, in order to delay the transfer of heat between the metal components, curbing heat conduction from the metal support to the cooled mold.