METHOD AND EQUIPMENT FOR CONTROLLING THE TEMPERATURE OF SOLID PARTICLES IN POLISHING PROCESSES

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application relates to and claims the benefit and priority to International Application No. PCT/ES2024/070344, filed Jun. 3, 2024, which claims the benefit and priority to Spanish Patent Application No. P202330448, filed Jun. 2, 2023, each of which is incorporated herein by reference in its entirety.

OBJECT OF THE INVENTION

The invention relates to a method and to equipment for controlling the temperature of particles in polishing processes by means of solid particles, providing advantages and features to the function for which it is intended and which are described later on in detail.

The object of the present invention relates to a method applicable to polishing processes or surface treatment of materials by means of solid particles, particularly relevant in electropolishing systems by means of solid particles loaded with an electrolyte and located inside a container, with the aim of controlling the temperature of the particles. During the polishing or electropolishing process by means of solid particles, a lack of temperature control may occur either due to the Joule effect generated during conduction of electrical current through the particles or the part to be polished, or due to friction or a combination of both effects. These temperature fluctuations can affect both the results of the surface treatment and the degradation of the solid particles, thereby reducing their useful life, affecting the conductivity and therefore the effectiveness of the treatment, which may no longer be homogeneous and/or repetitive.

Furthermore, a second aspect of the invention relates to temperature adjustment equipment, such as cooling equipment, applicable to a container of a polishing system by means of solid particles via a liquid environment, which comprises a circuit with a specific filter that forces only the circulation of the liquid, with the possibility of its recirculation after being directed through a heat exchanger and being returned to the container again.

TECHNICAL FIELD

The field of application of the present invention falls within the industry sector dedicated to surface treatment, encompassing the industrial sector dedicated to the treatment of metal surfaces, with applications in any field, and particularly covering electropolishing processes by means of solid particles.

BACKGROUND

Methods for polishing surfaces in which the parts to be treated are polished by friction and/or through conductive particles incorporated into a container are known in the state of the art.

For example, document PCT/ES2017/070247 discloses a “Method for smoothing and polishing metals via ion transport by means of free solid bodies, and solid bodies for carrying out said method”, which, after the connection of the parts to be treated to the positive pole (anode) of a current generator, includes the friction of the part with a set of particles made up of free electrically conductive solid bodies charged with a negative electrical charge and the introduction of said parts into a container or tank, in friction with a set of particles that are incorporated into said container and that contact electrically with the negative pole (cathode) of the current generator.

One problem associated with said method is that during the polishing process by means of solid particles containing an electrolyte inside a container, the particles vary their temperature due to physical phenomena that occur during the surface treatment process, such as conduction of current or friction forces.

This variation in temperature may alter the result of the treatment and degrade the solid particles, causing a decrease in their useful life. Furthermore, the increase in temperature also affects qualities such as conductivity, and therefore the polishing process, which depends on the conductivity of the process, is not homogeneous and/or repetitive. This means that, depending on the temperature of the particles, the polishing process is one or another, which may not be acceptable for the desired result in certain products.

Therefore, an objective of the present invention is the development of a method and equipment for controlling the temperature of particles.

The existence of temperature control systems in polishing systems, either by liquid recirculation or by direct contact by means of heat exchangers, is known. By applying these methods in a polishing system by means of solid particle friction and/or conductive solid particles, it is not possible to achieve sufficient thermal control to ensure optimal, homogeneous, constant and repetitive results.

By applying thermal regulation by recirculating the product through a circuit through which heat is exchanged, as can be found in conventional electropolishing systems. In this case, there is a problem associated with the inability to pump the particles, since they are not inside a fluid that does not meet the features for the assembly to be pumpable. Given the difficulty in recirculation and the high probability of clogging the recirculation system, thermal control using this method is not possible.

The systems that the following invention applies to are defined by discrete media and do not exhibit physical continuity between the elements that form up, i.e., the particles. When attempting to carry out thermal control, introducing a resistive or conductive element that acts as a heat exchanger, either as a heat pump or refrigeration machine, by immersion into the system, the greatest difficulty encountered by the particles to transfer heat when compared to other liquid systems involves an ineffective and highly heterogeneous system. In the event that the solid particles are some types of ceramic or polymer materials, the efficiency of the thermal control process is reduced since they have a low thermal conductivity.

In the same way as previously described, thermal control by means of a heat exchanger system located at the periphery of the container is inefficient, since an excessive thermal gradient would be obtained from the center to the periphery thereof.

The present invention aims to provide a method and mechanism with efficient temperature control that can be carried out prior to, during or after the surface treatment, and which overcomes the difficulties set out above.

Therefore, the objective of the present invention is the development of an alternative method and equipment that is more efficient in controlling the temperature of particles when the polishing process is carried out in an environment with the presence of a liquid.

Furthermore, and as a reference to the current state of the art, it should be noted that at least the applicant is unaware of the existence of any other method or equipment that exhibits technical and constitutive features equal or similar to those set out herein.

DESCRIPTION OF THE INVENTION

The method and equipment for controlling the temperature of particles in polishing processes by means of solid particles and/or with solid particles loaded with an electrolyte in an at least partially liquid environment proposed by the invention are configured as a solution to the aforementioned objective.

Specifically, as noted above, the invention proposes a method applicable to polishing processes by means of solid particles and/or with solid particles loaded with an electrolyte, immersed in a liquid, that is conductive or not, inside a container, which purpose is to control the temperature of the particles, preventing an increase in the temperature produced in the process due to, for example, friction or the joule effect from degrading the particles, thereby reducing their useful life, affecting the conductivity and therefore the effectiveness of the process that may no longer be homogeneous and/or constant or repetitive.

For this, one method comprises:

• • a step of aspirating the liquid contained in the container where the particles are immersed;
  • in the event of opting for a particular embodiment of the invention in which the same liquid is recirculated through a closed circuit, a step of thermally adjusting or conditioning said liquid, preferably by passing it through a heat exchanger located outside the container; and
  • a step of reincorporating the liquid into the container to, in turn, adjust the temperature of the particles.

It is worth mentioning that in the second step in which the thermal adjustment or conditioning process of the liquid is described, it can be carried out by means of a single liquid in a closed circuit or by means of a feed liquid, in such a way that said liquid is constantly and continuously renewed, without recycling or reconditioning the liquid in a closed circuit.

Furthermore, it is important to highlight that to correctly carry out the described aspiration of the liquid, it is advisable to prevent the particles from being aspirated together with said liquid in the aspirating step, since this can affect both the thermal adjustment or conditioning process of the liquid in the exchanger as well as the polishing process that can continue to be carried out in the container during the temperature adjustment process of the liquid, since the polishing and the thermal adjustment or conditioning of the liquid can occur simultaneously, thus avoiding the interruption of productivity.

For this reason, in some particular embodiments of the invention, prior to or in the very step of aspirating the liquid, the method comprises a step for filtering the liquid prior to the thermal adjustment or conditioning step, which prevents the particles from passing towards the heat exchanger from the container, together with the liquid to be thermally adjusted.

Furthermore, as mentioned above, a second aspect of the present invention relates to temperature adjustment equipment applicable to a container of a polishing system by means of solid particles in an at least partially liquid environment according to the method described above, which comprises:

• • a duct circuit with an inlet and an outlet in the container;
  • a suction pump, suitable for causing the liquid to circulate through the duct circuit;
  • a filter equipped with a fine mesh of such a size that it allows the liquid aspirated by the pump to pass through it, but not the particles; and
  • a heat exchanger that allows the thermal adjustment or conditioning of the liquid prior to its entry into the container; in which, in the event of working in a continuous recirculation mode in a closed circuit, it redirects the output liquid after passing through the filter for its conditioning prior to entering the re-entry circuit to the container.

In some cases, the inlet to the circuit of the liquid aspirated by the pump is located at the bottom of the container and the outlet of the liquid already thermally adjusted for its return to the container is located at the top thereof. This configuration has advantages both in the liquid circulation method and in the efficiency of temperature exchange between the liquid and the particles.

In a particular embodiment of the invention, the filter is configured as an elongate part that is attached to the wall of the container, having a lower portion that defines a body with an equally long and narrow inlet mouth, where it incorporates the mesh that prevents the particles from passing through it, and an upper portion that connects to the line of the circuit in which the suction pump is inserted.

Moreover, in some cases, the heat exchanger is a plate exchanger with one-way joints for liquids/liquids, where the liquid in the circuit from the container runs through them alternately and counter currently with a cooling or heating fluid that circulates through the remaining plates and is introduced into the exchanger through respective inlet and outlet connections.

Finally, in a particular embodiment of the invention, the duct circuit of the equipment comprises a return line to the container that, starting from the exchanger, directs the liquid to the top of the container and from which it falls inside the same by gravity.

DESCRIPTION OF THE DRAWINGS

To complement the description being made and to make the features of the invention more readily understandable, drawings are attached to the present specification as an integral part thereof, in which the following is depicted in an illustrative and non-limiting manner.

FIG. 1 shows a schematic perspective view of a container or tank used in a polishing process by means of solid particles in an at least partially liquid environment, in which an exemplary embodiment of the equipment for controlling the temperature of particles has been incorporated, showing the main parts and elements comprising it, as well as the arrangement thereof.

FIG. 2 shows a section view of the container or tank with the equipment of the invention shown in FIG. 1.

FIGS. 3, 4 and 5 show respective front, rear and section perspective views of a filter comprised in the equipment, showing its configuration and main parts.

FIGS. 6, 7 and 8 show respective perspective, top plan and elevation views of an example of the heat exchanger comprised in the equipment.

FIG. 9 shows a plan view of the container or tank with the equipment for controlling the temperature of the particles, incorporated inside a cooling jacket in this particular case.

FIGS. 10 and 11 show respective section views of the container or tank with the cooling jacket, according to the section A-A indicated in FIG. 9, where FIG. 11 is a container or tank with a central elevation.

PREFERRED EMBODIMENT OF THE INVENTION

In view of the aforementioned figures, and in accordance with the numbering adopted, a non-limiting exemplary embodiment of the equipment for controlling the temperature of particles in polishing processes by means of solid particles with electrolyte in a liquid environment of the invention is shown, which comprises what is described in detail below.

As shown in FIGS. 1 and 2, the equipment (1) of the invention, particularly applicable to polishing processes of parts (not represented) by means of solid particles (2) with an electrolyte, immersed inside a container (3), together with the presence of a mediating liquid (4), that is conductive or non-conductive, the equipment comprises:

• • a duct circuit (10), suitable for circulating the liquid (4), which has an inlet mouth (101) and an outlet mouth (102) in the container (3);
  • a suction pump (11), with power suitable for causing the liquid (4) to circulate throughout the entire path of the duct circuit (10);
  • a filter (12) equipped with a fine mesh (121) with a lumen size such that it allows the liquid (4) when aspirated by the pump (11) to pass through it, but not the solid particles (2); and
  • a heat exchanger (13), inserted in the duct circuit (10) downstream of the filter (12) and of the pump (11), where the liquid (4), as it passes through the same, is thermally adjusted before returning to the container (3) through the outlet mouth (102).

Preferably, as shown in FIG. 2, the inlet mouth (101) to the duct circuit (10) from which the liquid (4) is aspirated by the pump (11) is integrated into the filter (12). and located at the bottom of the container (3). The aspiration cycle with which the pump (11) is configured can be combined with one or more expiration cycles, which can avoid possible clogging problems in the filter (12), increasing flow and thermal exchange efficiency. In some cases, in order to contribute to the foregoing, a stirring device, not represented in the figures, can be located, for example, at the bottom of the container (3), which helps avoid excessive compaction of the particles (2) in areas close to the inlet mouth (101).

Preferably, the outlet mouth (102) of the duct circuit (10), from which liquid (4), already thermally adjusted, is returned to the container (3), is at the top thereof. Preferably suspended above the surface of the liquid (4) contained in the container (3), so that after thermal adjustment, it falls inside the same by gravity. It is possible to vary the place where the outlet mouth (102) is located along the vertical axis, from the highest area to the lowest. It is also possible to have different numbers of outlet mouths (102) along the entire perimeter of the container (3), in order to improve recirculation efficiency, along with the homogeneity of the temperature inside the container (3).

Preferably, as shown in FIGS. 3 to 5, the filter (12) consists of a device comprising a hollow body (122) of elongate configuration that is attached to the wall of the container (3), having a lower portion (123) that has an equally long and narrow front inlet opening (124), where it incorporates the mesh (121) that allows the liquid (4) to pass through it and prevents the particles (2) from passing through it, and an upper portion (125) perforated and internally separated from the lower portion (123) in the top of which it has a support (126) for fastening the device to the upper edge of the container (3). The place where the filter (12) and the suction opening (101) are located can vary along the vertical axis, from the highest area to the lowest. It is also possible to have different numbers of inlet/aspirartion mouths (101), with their respective filters (12), along the entire perimeter of the container (3), in order to improve aspiration efficiency, along with the homogeneity of the temperature inside the container (3).

Furthermore, said body of the filter (12) incorporates therein a tube (103) that runs along its entire length and has a splice connector (127) at the top, acting as an extension of the duct circuit (10) with the inlet mouth (101) at its lower end, through which the liquid (4) rises.

Moreover, taking into account FIGS. 6 to 8, it is shown how, preferably, the heat exchanger (13) is a plate exchanger (131) provided with a first pair of inlet (132) and outlet (133) connections, for coupling to the duct circuit (10) through which the liquid (4) from the container (3) passes, alternately running through half of said plates (131), and a second pair of inlet (134) and outlet (135) connections, intended for coupling to another circuit (not shown) of fluid that cools or heats and circulates through the remaining plates (131). Optionally, the container (3), as shown in FIGS. 9 and 10, is incorporated inside a cooling jacket (5) that surrounds it externally and has a cooling fluid inlet (51) at the bottom and a cooling fluid outlet (52) at the top. Furthermore, for said cooling jacket (5) to have a greater effect, the container (3) optionally defines a central elevation (31), such that the liquid (4) is always closer to its walls.

In some configurations, an emulsifying element of the mediating liquid (4) can be located in the recirculation circuit (1), for example, located in the tube circuit (10). This can contribute to greater efficiency in controlling the temperature of the medium, while providing advantages in the finish obtained during the surface treatment.

Having sufficiently described the nature of the present invention, as well as how to implement it, it is not considered necessary to further explain it so that any person skilled in the art can understand its scope and the advantages derived from it.