Solids for smoothing and polishing metals by ion transport

Abstract

The invention relates to a method for smoothing and polishing metals by ion transport through free solids, and to an electrically conductive solid for implementing said method, consisting in connecting a component (1) to the positive pole of an electric current generator, through a fixing element (2) associated with the device, and subjecting it to friction with particles (4) of a free solid, said free solid having electrical conductivity and contained in a container (3) having a gas environment occupying interstitial spaces (5) and which is in electrical contact with the negative pole (cathode) of the electric current generator, directly or through a ring acting as cathode, through the container (3). The solid is a particle (4), which has porosity and affinity to retain an electrolyte liquid below the saturation level, and has electrical conductivity.

Description

[0001] This application is a divisional application of application number 201780025853.2, application date April 24, 2017, and invention name “Method for smoothing and polishing metal by ion transport of free solid and solid for performing the method”.

[0002] Purpose of the Invention

[0003] The present invention relates to solids for smoothing and polishing metals by ion transport. The present invention relates to a method for smoothing and polishing metals by ion transport via free solids and also to conductive solids so that they can be used to implement said method. The method and solids offer advantages and novel features that are significantly improved over those currently known in their field of application, which advantages and novel features are disclosed in detail below.

[0004] The object of the present invention specifically relates to a method for smoothing and polishing metal parts (for example, dentures), which is based on ion transport by means of free solids of small size. These solids refer to particles that are essentially different in that they are conductive and are placed together in a gas environment. The metal parts are arranged so that they are connected to the positive pole of an electric power source (for example, a DC generator, and preferably with motion), and the group of solids (particles) is in electrical contact with the negative pole of the power source. The solids are the second feature of the invention, which consist of particles that can retain a certain amount of electrolyte inside, so that they have an electrical conductivity that converts them into electrical conductivity. Technical Field

[0005] The field of application of the invention belongs to the industrial sector engaged in the grinding and polishing of metal parts (eg dental prostheses of stainless steel), in particular involving electrolytic polishing processes by particles. Background Art

[0006] With reference to the prior art, it should be pointed out that different systems for smoothing and polishing metals in devices with free solids (particles) are known.

[0007] Thus, long ago, various devices were used in which mechanical abrasion took place by using particles not fixed to any support, having different geometries and sizes and being harder than the material to be treated.

[0008] Due to the relative movement generated between the part to be treated and the particles, the device generates friction of the particles on the part to be treated.

[0009] These include, for example, rotating containers (drums), vibrating containers or particle ejectors.

[0010] However, all systems based on direct mechanical abrasion, as described above, have the serious drawback that they affect components with little uniformity, which means that, due to a given ratio between the pressure exerted by the grinding means (particles) on the component and the amount of material eroded, the wear and grinding to which the protruding areas of the component are subjected is in many cases excessive.

[0011] Furthermore, in many cases the global mechanical energy acting in the system is responsible for damage to components due to deformations caused by strokes and excessive stresses.

[0012] On the other hand, systems based on mechanical wear produce surfaces with plastic deformations on the metal parts and, while doing so, they inevitably clog up with non-negligible amounts of foreign matter which in many cases determine the unsuitability of the treatment because of contamination of the surface layer of the material.

[0013] Likewise, polishing systems by electroplating treatment are known, in which the metal part to be treated is immersed in an electrolyte and without solid particles acting as anodes, called electrolytic polishing.

[0014] The advantages of the methods described are that they produce surfaces without the surface contamination of the proprietary mechanical grinding methods disclosed above.

[0015] At present, in many cases, the leveling effect on roughness greater than a few micrometers is insufficient, so the treatment is mainly used as a finishing of the existing mechanical abrasion method.

[0016] In addition, there is an electroplating method in which a metal part to be treated is immersed in an electrolyte containing solids (particles) that move freely therein.

[0017] The electrolyte developed for the method produces a thicker anode layer than in the case of electroplating methods without particles, so that when the included particles interact mechanically with the anode layer, effective smoothing of up to 1 mm in roughness occurs.

[0018] However, it is also true in another case that in many cases the electroplating methods used hitherto produce defects in the shape of pinholes or in stepped surfaces related to the structure and crystal composition of the metal to be treated, and in many cases the use of the residues is limited to parts which, due to their composition (alloys) and the molding process and forming, experience has shown that they can be processed without exhibiting the said defects in an unacceptable manner.

[0019] The object of the present invention is therefore to develop an improved smoothing and polishing system for metal parts which is efficient and avoids the disadvantages and problems disclosed above, and it should be said that at least the applicant is not aware of the existence of any other similar method of this type or invention having the same characteristics as the one claimed. Summary of the invention

[0020] The method for smoothing and polishing metals by ion transport by means of free solids and the conductive solids used to implement said method proposed by the present invention are therefore configured to be novel in their field of application because, when implemented, the above-mentioned objects are satisfactorily achieved. The characteristic details that enable the invention to achieve its objects and distinguish it from the prior art are conveniently included in the final claims appended to this description.

[0021] Specifically, as described above, on the one hand, the present invention proposes a method for smoothing and polishing metal parts (for example, metal parts for dentures, but this is not meant to be limiting) based on ion migration in an innovative manner using free solids (particles) that are conductive in a gas environment, and on the other hand, proposes a solid composed of particles having a variety of shapes that have porosity and affinity to retain a certain amount of electrolyte liquid to make them conductive.

[0022] More specifically, the method of the present invention provides the following steps:

[0023] Connect the part to be treated to the positive pole (anode) of the current generator;

[0024] After they are fixed, the parts to be treated are rubbed against a set of particles consisting of conductive free solids that are negatively charged in a gaseous environment (for example, air).

[0025] The friction of the component against the particles can be achieved, for example, by a particle stream propelled by a gas or discharged from a centrifugal mechanism or by a system with brushes, winders or any other suitable pushing elements capable of moving and pressing the particles against the component surface.

[0026] In a preferred embodiment, the component is introduced into a container having a group of particles in contact with each other and with the negative pole (cathode) of the current generator. In this case, the component moves relative to the group of particles, for example after a circular motion.

[0027] As for the particles constituting this electrically conductive free solid, they have a variable shape and size suitable for smoothing the roughness of the part to be treated, but in any case being larger than the roughness to be removed.

[0028] Additionally, the particles have porosity and an affinity to retain a certain amount of electrolyte liquid, giving them conductivity that makes them conductive.

[0029] It should be noted that the amount of electrolyte liquid retained by the particles was always below the saturation level, so that leaving free liquid on the particle surface was explicitly avoided.

[0030] Preferably, the composition of the electrolyte for polishing, for example, stainless steel is H2O: 90-99% and HF: 10-1%.

[0031] In this way, when the particles rub against the part to be polished, they very precisely determine the embossed areas where metal removal in the form of ions occurs.

[0032] The main advantage is that, unlike methods involving electrolytes with free solids, the method proposed by the invention is able to smooth and polish virtually any metal alloy without the effects of uneven erosion of the surface.

[0033] As described in the previous paragraphs, generally, when using electrolytes with free solids, pinholes and steps appear on the surface of the treated part, which is a reflection of the inherent differences in composition and properties between different areas of its crystal structure.

[0034] In the method of the invention, the particles with the electrolyte rub against a large part of the component to be treated. In the steady state of the method, there are always various electrical conditions of the particles.

[0035] Thus, in extreme cases, there are situations where particles act as electrical "bridges" through direct contact with other particles between the component and the cathode.

[0036] In this case, the particles in contact with the component displace a given amount of electrolyte, thereby wetting an area of ​​the component surface and exerting an electro-corrosive effect.

[0037] The products of this galvanic corrosion (salts) are locally present in said area.

[0038] At the other extreme, there are particles that are in contact with the component surface in an isolated manner and do not contact other particles after a maximum time.

[0039] In this case, the particles in contact with the component absorb the remnants (salts) of previous galvanic corrosion generated by other particles.

[0040] And, further at the other extreme, the method will be that when sufficiently high relative component-particle travel speeds are used and sufficient voltage is applied simultaneously to operate, the likelihood of large numbers of particles impacting the surfaces of these components in an isolated manner and simultaneously having sufficient charge to cause effective electrical corrosion is maximized.

[0041] In addition, there are an infinite variety of intermediate situations between these three extreme cases.

[0042] Therefore, the high efficiency and accuracy of the method can be explained by the rapid succession of particle-component contacts in the steady state.

[0043] The anode-cathode ion transport necessary to ensure stable behavior of the process occurs by diffusion through the particles.

[0044] Additionally, to a given extent, anode-cathode transport may also occur within a group of particles that facilitate ion transport.

[0045] Specifically, the method also shows the relevant capability of uniform smoothing and polishing in different scale ranges.

[0046] Thus, for example, for spherical particles with a diameter in the range of 0.3 to 0.8 mm and an average tangential velocity of the group of particles relative to the part to be polished of the order of 1 to 3 m / sec, the velocity in mm 2 The spherical particles are preferably sulfonated styrene-divinylbenzene copolymers and have a microporous structure.

[0047] In turn, evaluating the amount of metal removed between areas separated by centimeters, a great deal of uniformity can be perceived.

[0048] This means that the method of the invention has the ability to equalize or balance the effects of a large number of contacts (per particle) to a given degree, even though they occur between a wide range of circumstances.

[0049] It is also important to remember that the method of the invention allows the adjustment of the parameters of all the elements of the intervention, namely the voltage, the average value of the tangential velocity, the content of the electrolyte, the conductivity and the chemical composition of said electrolyte, the percentage between the particles and the surrounding gas.

[0050] When such adjustments are made appropriately and explicitly, limiting the effects of galvanic corrosion on relatively more exposed and protruding components relative to more concealed components is achieved on a centimeter scale.

[0051] The local average tangential velocity of particles on the protruding parts is higher than the local average tangential velocity on the hidden parts.

[0052] And, since the mentioned parameters are properly adjusted, what happens is that the average time of individual contacts (per particle) on the protruding areas is lower than the average contact time of individual contacts on the hidden areas, resulting in a lower electro-corrosion yield than obtained on the hidden areas.

[0053] This is because, in order to enable metal ion transport of the component, each contact area must first be polarized to a given threshold, which requires time and methods, as it can be appropriately adjusted, to allow the time required for polarization work to be carried out in the sense of a balanced result on a scale of centimeters.

[0054] The low yield for individual contacts on the protruding parts is balanced by higher numbers in terms of time and surface.

[0055] The disclosed method of smoothing and polishing metals by ion transport through free solids, and the conductive solids for carrying out said method, therefore, comprise innovations of hitherto unknown character, which, combined with the purpose for which they were designed, and the reasons for their practical utility, afford them sufficient basis to warrant the privilege of applying for exclusive rights. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to supplement the description already made and to help best understand the features of the present invention, the present specification is accompanied by the accompanying drawings, which constitute an integral part of the present specification. The following drawings are for illustrative rather than limiting purposes:

[0057] Figure 1 A schematic diagram showing the main elements of the method for smoothing and polishing metals by ion transport via free solids, which is the object of the present invention;

[0058] Figure 2 A schematic diagram of particles forming a solid according to the method of the present invention is shown, showing the porous structure of the particles making them conductive and their ability to retain electrolyte;

[0059] Figure 3 a schematic diagram of a portion of a rough surface of a part to be treated, together with several examples of the shapes that the particles used in the method may have, and the differences in size between them and the dimensions of the roughness can be seen symbolically; and finally

[0060] Figure 4 and Figure 5 They show similar Figure 1 The schematic diagram shown in , which plots the corresponding moments of the method, Figure 4 is a situation in which a group of particles forms a bridge of direct contact between the anode and cathode, while Figure 5 This is another situation where the particles brush the surface of the parts separately. DETAILED DESCRIPTION

[0061] With reference to the above-mentioned figures and according to the numbers used therein, it can be seen how, in a preferred embodiment of the method of the present invention, the metal part to be processed is fixed to the moving arm (not shown) of the device by means of a fixing element 2 (which may also be metal, including hooks, clips, claws or other), and the moving arm can perform orbital motion around the axis on a plane, and at the same time, the moving arm can perform a linear reciprocating displacement motion on a plane perpendicular to the orbit, such as Figure 1 As shown by the arrow line in .

[0062] The component 1 thus fixed and disabled from the orbital motion and the linear reciprocating displacement motion is introduced through the top into a container 3 of the device, which container contains a group of conductive particles 4 and air or any other gas occupying the space 5 of the interstitial environment existing between the conductive particles, so that the component 1 is completely covered by this group of particles 4.

[0063] Preferably, the shape of the container 3 is a cylinder having a closed lower end or bottom and an open top end.

[0064] In any case, the fixed element 2 is connected to the anode or positive pole of an electric current generator (not shown) arranged in the device, while the container (3) is connected to the negative pole of the generator acting as cathode either directly (because the container is metallic) or through a ring arranged to achieve this effect.

[0065] Logically, this device securely fixes the cylinder forming the container 3 so as to prevent it from shifting during the orbital movement and the linear reciprocating displacement of the fixing element 2 of the activation part 1 .

[0066] Finally, it should be pointed out that the amplitude of movement of the fixing element 2 provided by the arm of the device (not shown), as well as the dimensions of the container 3 containing the particles 4, are such that in any case it is impossible for the part 1 to be treated or any conductive part of the fixing element 2 to come into direct contact with the wall of the container (or, where appropriate, the ring acting as cathode).

[0067] consider Figure 2 , it can be seen how the particles 4 constituting the free conductive solid of the method according to the invention are solids having porosity and affinity to retain a certain amount of electrolyte liquid to make them conductive, the amount of electrolyte liquid retained by the particles 4 being always below the saturation level, thereby explicitly avoiding the presence of free liquid on the surface of the particles.

[0068] Preferably, the composition of the electrolyte used for polishing, for example, stainless steel is: H2O: 90-99%; HF: 10-1%.

[0069] On the other hand, Figure 3 As shown in the example of , the particles 4 are bodies of variable shape and size suitable for smoothing the roughness of the part 1 to be treated and preferably greater than the roughness removed from said surface.

[0070] Finally, in Figure 4 and 5 In the figures, two examples of extreme cases of the method are described, whereby smoothing and polishing of the component 1 is achieved by contact between the conductive particles 4 and the surface of the component 1 to be treated. Figure 4A group of particles 4 is shown forming a bridge in direct contact between the anode (via a fixing element 2 in contact with the metal part 1) and the cathode (via a container 3), Figure 5 The particles 4 are shown brushing the surface of the component 1 respectively, as described in the previous paragraph.

[0071] Having fully disclosed the nature of the invention and the manner of implementing it, there is no need to prolong its explanation so that a person skilled in the art understands its scope and the advantages arising therefrom, and it should be noted that, in its essence, it can be implemented in other embodiments that differ in the details indicated for exemplary purposes and that the protection sought should extend as long as the basic principle thereof is not changed, altered or modified.

[0072] Each of the non-limiting examples below may stand on its own or may be combined with one or more of the other examples in various arrangements or combinations.

[0073] Example 1 is a method for smoothing and polishing metals by ion transport via free solids, comprising connecting the part 1 to be treated to the positive pole (anode) of an electric current generator, wherein the method comprises the steps of:

[0074] The component 1 is rubbed against a set of particles 4 consisting of conductive free solids that are negatively charged in a gaseous environment.

[0075] In Example 2, the subject of Example 1 includes the steps:

[0076] The component 1 is introduced into a container 3 and rubbed against a group of particles 4 contained in the container 3 and in electrical contact with the negative pole (cathode) of the current generator.

[0077] In example 3, the subject matter of example 2 consists in that the electrical contact of the particles 4 with the negative electrode of the current generator is performed through the container 3 acting as cathode, since the container 3 is directly connected to the negative electrode of the current generator.

[0078] In example 4, the subject matter of any of examples 1 to 2 comprises that the electrical contact of the particles 4 with the negative pole of the electric current generator is performed by a ring arranged in the container 3 as cathode.

[0079] In Example 5, the subject matter of any one of Examples 1 to 4 includes: the friction between the part 1 to be treated and the particles 4 is performed by the movement of the part 1, and the movement of the part 1 is determined by the action generated by the device associated with the fixing element 2, wherein the part 1 is fixed in the container 3 by the fixing element 2.

[0080] In Example 6, the subject matter of Example 5 includes: the motion performed by the device is an orbital motion around an axis in a plane and, at the same time, a linear reciprocating motion in a plane perpendicular to the orbit.

[0081] In Example 7, the subject matter of any one of Examples 1 to 6 includes that the gaseous environment occupying the interstitial spaces 5 between the particles 4 present in the container 3 is preferably air.

[0082] Example 8 relates to a solid for carrying out the method for smoothing and polishing metals by ion transport through a free solid as described in Examples 1 to 7, wherein the solid is composed of a conductive solid consisting of particles 4 having porosity and affinity to retain a certain amount of electrolyte liquid to make them conductive.

[0083] In Example 9, the subject matter of Example 8 includes that the amount of electrolyte retained by the particles 4 is always below the saturation level, thereby avoiding the presence of free electrolyte liquid on the surface thereof.

[0084] In Example 10, the subject matter of any one of Examples 8 to 9 includes: the size of the particles 4 is larger than the roughness to be removed from the surface of the part to be treated 1 .

[0085] In Example 11, the subject matter of any one of Examples 8 to 9 includes: the composition of the electrolyte for polishing is H2O: 90-99% and HF: 10-1%.

Claims

1. A solid used as a free solid for smoothing and polishing metals by ion transport, The free solid has porosity and affinity and contains a certain amount of electrolyte liquid inside to make the free solid conductive. The amount of electrolyte liquid contained in the free solid is below a saturation level, thereby avoiding the presence of free electrolyte liquid on the surface of the free solid.

2. The free solid according to claim 1, wherein The free solid bodies have different shapes.

3. The free solid according to claim 1 or 2, wherein The electrolyte liquid used for polishing has a composition of 90%-99% H2O and 10%-1% HF.

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