Abrasive member for dry grinding and polishing and method of making same

Abstract: A flexible abrasive member comprising a first porous layer of mesh, non-woven or perforated sheet, conductive or non-conductive material to which at one side deposits are deposited by way of any metal plating technique of either the electrolytic, electroless or vacuum deposition type, or any galvanic process, abrasive particles being embedded in the metal deposits, a layer of filling material, such as a resin, being present between the deposits which filling material is bonded to said first porous layer and/or the deposits, and at least a second porous layer of mesh, non-woven or perforated sheet, conductive or non-conductive material being present and being laid substantially along one side of said first porous layer, wherein the side edge of said deposit has at least one annular groove along at least part of the circumference of said deposit.

Description: The invention is related to a flexible abrasive member and to methods of making same. The abrasive member comprises a first porous layer of, by example, mesh, non-woven or perforated sheet, conductive or non-conductive material to which at one side deposits are deposited by way of any metal plating technique of either the electolytic, electroless or vacuum deposition type, or any galvanic process, abrasive particles being embedded in the metal deposits, a layer of filling material, such as a resin, being present between the deposits which filling material is bonded to said first porous layer, and at least a second porous layer of, by example, mesh, non-woven or perforated sheet, conductive or non-conductive material being present and being laid substantially along one side of said first porous layer Such flexible abrasive member, as well as its method of production is known from EP-A-623424. Abrasive members for grinding and polishing are well known in the art. Two types of such abrasive members are known. Firstly the type for dry grinding and polishing comprising by example siliciumcarbide or aluminiumoxide, having a short life time. Secondly the type for wet grinding and polishing comprising diamond particles as abrasive particles, which type may only be applied using some coolant, by example water. When this second type of abrasive member is used for dry grinding and polishing the life time is very short. In some applications it is desired to use an abrasive member with diamond particles while coolant may affect the product to be grinded or polished or any object nearby, whereby using coolant is not allowed. Presently there are no abrasive members well suited for these applications. The significant characteristic of an abrasive members is its resistance to wear and tear due to thermal effects and mechanical effects. In practice the problems in grading up this resistance to increase the life time of the abrasive member are that flexibility of the abrasive member must be maintained, that moldable materials having a high specific heat conductive capacity are known to have generally bad characteristics concerning resistance to wear and tear due to mechanical effects, that a real strong bonding between all materials in the composition of the abrasive member, in particular between the abrasive particles and the backing material of the abrasive member, must be achieved, and that it must be possible to produce this composition easily and with low production cost. The object of the invention is to provide a flexible abrasive member with abrasive particles for dry grinding and polishing with a high mechanical and thermal resistance to wear and tear so that a much longer life time is achieved than can be achieved by the conventional flexible, abrasive members. This object is achieved by an abrasive member according to claim 1. The layer of filling material may extend substantially into and at least along part of this annular groove. Hereby part of said layer is encapsulated by the groove thus increasing resistance to mechanical wear and tear. The abrasive member is reinforced by the second porous layer whereby its mechanical resistance is increased, while its flexibility is maintained. Moreover its thermal resistance is increased for the amount of heat conducting material is increased by applying the other layer. The annular groove is achieved by way of any metal plating technique of either the electrolytic, electroless or vacuum deposition type, or any galvanic process. Generally a groove may be achieved by methods known. Obviously a groove per deposit in the side edge of a deposit having micro to milli dimensions, while hundreds to thousands of deposits are present per abrasive member, is hardly to achieve. By the method according to the present invention such a groove is easily achieved using the same technique that creates the deposit itself. Preferably the layer of filling material consists of material having a heat resistant point substantially less than or about 200°C. Herein the heat resistant point is the temperature above which the material fails, i.e. melts and thereby deforms and affects the abrasive member in its functioning. Material having a higher heat resistant point is a much complexer type of material and in practice is much more expensive than a material having a said heat resistant point. The filling material may be polyurethane, acrylicacetate or epoxyresin. It is possible that a further porous layer at least partially is interwoven or spot welded with at least one of the first and second porous layers. The present invention will do when either two or more porous layers are laid on top of each other or two or more porous layers are interconnected to eachother, by example as being interwoven or spot welded with eachother. Just the presence of two or more layers or interstices between two or more mesh, non-woven or perforated sheet materials is important as to enable the deposition of a deposit having an annular groove, which groove is by example achieved by embedding these two or more layers in the deposit. At least the second porous layer may at least partially be interwoven or spot welded with the first porous layer. The first porous layer may have a high mesh count, or open structure, and the second porous layer has a small mesh count, or dense structure. Hereby electrodeposition of metal onto both layers is improved because the straight line between anode and cathode is less or hardly interferred with by any object, while a greater surface of the cathode is exposed to the electrodeposition bath. Advantageously the mesh count of the second porous layer is 2.5 to 6 times less than the mesh count of the first porous layer. In practice this range gives the best results. A layer of any resin material, such as any glue material, may extend along one side of the first porous layer and substantially between all deposits. This resin material may be used for filling the remaining space between deposit, layer of filling material and the second porous layer, thus reinforcing the abrasive member and thus increasing the resistance to wear and tear. Moreover, the glue material may be used to attach the abrasive member to the backing layer mentioned above, thus also increasing the resistance to wear and tear. Herein the layer of resin material embeds at least part of the second porous layer thus causing a better bonding effect. This layer of resin material may be bonded to the second porous layer and/or the layer of filling material and/or the deposits. In general terms, the object of the present invention is achieved by enlarging the heat conductive capacity of the abrasive member and reinforcing the bonding of the several materials to eachother. The heat conductive capacity is enlarged firstly by increasing the mass of the abrasive member without loosing the flexibility required and secondly by using filling material with a higher specific heat conductive capacity, which material has not yet been used in long life time abrasive members for dry grinding of polishing for its really bad bonding characteristics. Increasing the mass of the abrasive member is achieved basically by applying more material. Increasing the mass of the abrasive member enlarges the amount of heat leaking away per time unit so that more heat may be fed to the abrasive member by dry grinding or polishing on the spot. It is important not to loose any flexibility of the abrasive member so a flexible filling material is applied just as is in the well known abrasive members. Using filling material with a higher specific heat conductive capacity, naturally enlarges the amount of heat leaking away per time unit or being absorbed. A larger heat conductive capacity enlarges the resistance to wear and tear of the abrasive member. The bonding of the several materials to eachother is reinforced firstly by providing a deposit with a substantially U-shaped side profile in sectional view, secondly by providing a second porous layer of, by example, mesh, non-woven or perforated sheet material along the first porous layer of, by example, mesh, non-woven or perforated sheet material, which second porous layer has a less mesh count or a more open structure than the first porous layer, and thirdly by applying glue to the portions where no deposits are present in the second porous layer. The substantially U-shaped side profile in sectional view of the deposit encapsulates part of the filling material applied to the portions of the first porous layer where no deposits are present. Hereby a mechanical enclosure is achieved rather than a chemical bonding of the filling material to the deposit material, which mechanical enclosure has a higher resistance to wear and tear than this chemical bonding. The second porous layer laid on the well known first porous layer provides per deposit a larger surface for attaching the deposit material. Moreover, tearing of the abrasive member is rendered more difficult because more attachements per deposit have to be teared while naturally tearing two layers of, by example, mesh, non-woven or perforated sheet materials at one time is more difficult than tearing only one such layer. The mesh count or density of the second porous layer of, by example, mesh, non-woven or perforated sheet material is less than that of the first porous layer for convenience of depositing in a galvanic process. Any relation between the grade of the first relative to the second porous layer, although in practice the best results have been achieved using a relation non equal to one, in particular greater than one. The better the depositing takes place the more the mechanical resistance to wear and tear of the abrasive member is increased. Applying glue to the portions where no deposits are present in the second porous layer reinforces chemically the bonding between filling material, deposit and both porous layers, while the flexibility of the abrasive member is not decreased. Hereby the resistance to mechanically caused wear and tear of the abrasive member is increased. When one of the porous layers is made of conductive material, this layer itself may form the cathode in the electrolytic process. Thereby a separate cathode may be omitted. This layer will then be indicated as being a 'permanent cathode'. The present invention also relates to a method of making the abrasive member of the present invention. Several methods of making abrasive members are well known in the art. The methods known, are not suited for making the abrasive member of the present invention because no annular groove in the side edge of the deposits may be achieved by way of any metal plating technique known of either the electrolytic, electroless or vacuum deposition type, or any galvanic process. One method according to the present invention (see claim 13) comprises the steps of applying electrically insulating material, i.e. a layer of filling material, over selected areas of a first porous layer so that in a subsequent depositing step a metal layer is deposited only over the remaining non-covered discrete areas of the surface of said first porous layer, connecting said first porous layer to a cathode, by example a metal face which forms the cathode in the electrolytic process, electrolytically depositing metal through the pores or interstices of said first porous layer causing a firm bond between the metal deposits thus built up and the first porous layer preferably in the presence of abrasive material, continuing the electrolytical deposition until metal has been deposited beyond the height of the layer of filling material above the top surface of the cathode, causing the creation of an radial extending annular rim, turning the first porous layer including the layer of filling material and the deposits up side down the deposits created now forming the cathode in the electrolytic process, laying a second porous layer of, by example, mesh, non-woven or perforated sheet, conductive or non-conductive material onto the free surface of the first porous layer, restarting the electrolytic process causing metal to be deposited through the pores or interstices of the second porous layer embedding at least part of the second porous layer by creating relative to a deposit created earlier a radial extending annular rim. By this method an abrasive member is achieved having an annular groove along the circumference of the deposit. This groove is substantially filled with material of the layer of filling material so that this layer is encapsulated by the groove. Hereby a mechanical enclosure is achieved, which causes a high resistance to wear and tear. To improve the high resistance to mechanical wear and tear of the first method according to the invention mentioned above, it is preferred to put the member created into a reactivation bath before the step (see method according to the invention mentioned above) of laying the second porous layer onto the free surface of the first porous layer, for working the surfaces of the deposits created, which surfaces has laid onto the surface of the cathode, as to prepare said surfaces for extended metal deposition onto these surfaces. Working the surfaces of the deposits affects the surface structure of the deposit already formed whereby a much better coalesce between the extended metal deposition and said surface structure is achieved. Another method according to the present invention is defined in claim 15. This method is based upon the same idea as the method according to the invention mentioned above, but is easier to do, whereby a less clear groove is achieved. Nevertheless, this method provides a good compromise to ease of production, and thereby cost of production, and resistance to mechanical tear and wear. The composition of layers may be formed by two or more at least partially interwoven or spot welded porous layers of, by example, mesh, non-woven or perforated sheet material. As was mentioned above the present invention will do when either two or more porous layers are laid on top of each other or two or more porous layers are interconnected to eachother, by example as being interwoven or spot welded with eachother. Wenn using a material consisting of two or more interwoven or spot welded layers of porous material the objects of the present invention may be achieved by using an even easier method according to the invention. At least one side of the member created may be applied with a layer of resin, such as a glue material, by example epoxy, polyester or polyurethane. Hereby the member may be attached to a backing layer thereby reinforcing the abrasive member and causing higher resistance to wear and tear due to mechanical or thermal influences. The electrically insulating material, i.e. said layer of filling material, may be applied by way of producing of a printing image including the steps of applying a photographic resist onto the surface of the first porous layer, exposing the resist to a film having the desired copy, development of the image thereby leaving a resist pattern, and etching of the surface to remove the resist material around the resist pattern thereby opening the first porous layer where the resist material is removed to define an etched image on the surface. Although this method is well known in screen printing techniques, and in providing a mask as part of a metal deposition process, it has not yet been used to provide the filling layer. The possibility to use a filling material having a much lower heat resistant point enables the use of less complex material whereby screen print techniques may be employed. The second porous layer may be an electrically conductive material. Hereby metal is deposited onto sections of this second porous layer also resulting in better bonding and embedding whereby the resistance to mechanical wear and tear is increased. One side of the member created may be applied to a backing layer, the bonding between said backing layer and the member created being achieved by the layer of glue material being applied earlier. As was mentioned before, a backing layer may reinforce the abrasive member and thus causes higher resistance to wear and tear due to mechanical or thermal influences. The invention will be further elucidated referring to two embodiments of the invention shown in the drawings, wherein: Figure 1 shows the result of the first four steps of one method according to the present invention; Figure 2 shows the result of the rest of the steps of the one method according to the present invention; Figure 3 shows the result of the steps of another method according to the present invention. In figure 1 a first embodiment of the abrasive member according to the invention is shown. The flexible abrasive member comprises a first porous layer 1 of, by example, mesh, non-woven or perforated sheet material to which at one side deposits 2 are deposited by way of any metal plating technique of either the electrolytic, electroless or vacuum deposition type, or any galvanic process, abrasive particles 3 being embedded in the metal deposits 2, and a layer 4 of filling material, such as a resin, being present between the deposits 2, which filling material 4 is bonded to the first porous layer 1 and/or the deposits 2. The flexible abrasive member is made by firstly laying the first porous layer 1 onto a metal face 9, which forms the cathode in the electrolytic process. Secondly the first porous layer 1 is applied with electrically insulating material, i.e. the layer 4 of filling material, over selected areas so that the metal layer is deposited only over the remaining non-covered discrete areas of the surface of the first porous layer. Thirdly metal 2 is electrolytically deposited through the pores or interstices of the first porous layer 1 causing a firm bond between the metal deposits 2 thus built up and the first porous layer 1. Preferably this is done in the presence of abrasive material 3 so that this material becomes imbedded in the deposits. Further the electrolytical deposition is continued until metal has been deposited beyond the height of the layer 4 of filling material above the top surface of the cathode 9, causing the creation of an radial extending annular rim 10. Then the member thus created, including the first porous layer 1, the layer 4 of filling material and the deposits 2, are taken off the face 9 and are turned up side down for continuation of the production process. In figure 2 the result of the extended metal electrodeposition to the abrasive member according to figure 1 is shown. Said production process is continued wherein the member turned up side down now forms the cathode in the electrolytic process. The following steps of the method according to the invention are firstly laying a second porous layer 5 of, by example, mesh, non-woven or perforated sheet material onto the free surface of the first porous layer 1 and secondly restarting the electrolytic process causing metal 12 to be deposited through the pores or interstices of said second porous layer 5 embedding at least part of said second porous layer 5 by creating relative to a deposit 2 created earlier a radial extending annular rim 11. Finally the abrasive member comprises a second porous layer 5 of mesh or non-woven conductive or non-conductive material laid substantially along one side of said first porous layer 1. As can be seen from figures 2 and 3 the mesh count of the second porous layer 5 is less than the mesh count of the first porous layer 1. By way of the method according to the invention in the side edge 6 of the deposit 2 at least one annular groove 7 along at least part of the circumference of the deposit 2 has been achieved. The layer 4 of filling material extends substantially into and at least along part of this annular groove 7. The layer 4 of filling material extends substantially between all deposits 2, and a layer 8 of a glue material, extends along one side of the first porous layer 1 and substantially between all deposits 2. A backing layer 14 is attached via the glue layer 8 to the abrasive member. The layer 8 embeds at least part of said second porous layer 5. After turning the abrasive member created as to continu metal electrodeposition a dividing line 15 is formed between the deposit 2 which has been created already and the extended deposition 12 which now has to be created. To improve the high resistance to mechanical wear and tear the member created may be put into a reactivation bath before the step of laying the second porous layer 5 onto the free surface of the first porous layer 1, for working the surfaces of the deposits created. This is done to affect the surface structure of the deposits 2 already formed whereby a much better coalesce between the extended metal deposition 12 and the surface structure 2 is achieved. In figure 3 another embodiment of the abrasive member according to the invention is shown. The flexible abrasive member comprises a first porous layer 1 to which at one side deposits 2 are deposited by way of any metal plating technique of either the electrolytic, electroless or vacuum deposition type, or any galvanic process, abrasive particles 3 being embedded in the metal deposits 2, and a layer 4 of filling material, such as a resin, being present between the deposits 2, which filling material 4 is bonded to the first porous layer 1 and/or the deposits 2. Further the abrasive member comprises a second porous layer 5 of mesh or non-woven conductive or non-conductive material laid substantially along one side of said first porous layer 1, and a layer 8 of a glue material, extending along one side of the first porous layer 1 and substantially between all deposits 2 embedding at least part of the second porous layer 5. This flexible abrasive member is made by firstly applying the first porous layer 1 with the second porous layer 5. Secondly both said first 1 and said second porous layer 5 are laid as one composition onto a metal face 9, which forms the cathode in the electrolytic process. Thirdly this composition of layers is applied with electrically insulating material, i.e. the layer 4 of filling material, over selected areas so that the metal layer 2 is deposited only over the remaining non-covered discrete areas of the surface of the composition of layers. Further metal is electrolytically deposited through the pores or interstices of the layers of the composition causing a firm bond between the metal deposits 2 thus built up and the porous layers. Preferably this is done in the presence of abrasive material 3 so that this material 3 becomes embedded in the deposits 2. Finally electrolytical deposition is continued until metal 2 has been deposited beyond the height of the layer 4 of filling material above the top surface of said cathode (not shown), causing the creation of an radial extending annular rim 10. By way of this method according to the invention in the side edge 6 of the deposit 2 an annular groove 7 along at least part of the circumference of the deposit 2 has been achieved. Relative to the groove 7 in the deposits according to figure 2 now a less clear groove 7 is achieved, mainly because rim 13 is quite smaller than rim 11. Nevertheless the layer 4 of filling material extends substantially into and at least along part of this annular groove 7 thus being encapsulated by the rims 10 and 13 and the deposit 2. The layer 4 of filling material extends substantially between all deposits 2, and a layer 8 of a glue material, extends along one side of the first porous layer 1 and substantially between all deposits 2.

Claims: A flexible abrasive member comprising a first porous layer (1) of, by example, mesh, non-woven or perforated sheet, conductive or non-conductive material to which at one side deposits (2) are deposited by way of any metal plating technique of either the electolytic, electroless or vacuum deposition type, or any galvanic process, abrasive particles (3) being embedded in the metal deposits (2), a layer (4) of filling material, such as a resin, being present between the deposits (2) which filling material (4) is bonded to said first porous layer (1), and at least a second porous layer (5) of, by example, mesh, non-woven or perforated sheet, conductive or non-conductive material being present and being laid substantially along one side of said first porous layer (1), characterized in that the side edge (6) of each said deposit (2) has an annular groove (7) along the circumference of each said deposit (2), and an annular rim (10) extending over the layer (4) of filling material. A flexible abrasive member according to claim 1, characterized in that said annular groove (7) is achieved by way of any metal plating technique of either the electrolytic, electroless or vacuum deposition type, or any galvanic process. A flexible abrasive member according to one of the preceding claims, characterized in that said layer (4) of filling material extends substantially into and at least along part of said annular groove (7). A flexible abrasive member according to one of the preceding claims, characterized in that said layer (4) of filling material consists of material having a heat resistant point substantially less than or about 200°C. A flexible abrasive member according to claim 4, characterized in that said filling material is polyurethane, acrylicacetate or epoxyresin. A flexible abrasive member according to one of the preceding claims, characterized in that a further porous layer at least partially is interwoven or spot welded with at least one of the first and second porous layers. A flexible abrasive member according to claim 6, characterized in that the second porous layer (2) at least partially is interwoven or spot welded with the first porous layer (1). A flexible abrasive member according to one of the preceding claims, characterized in that the first porous layer (1) has a high mesh count, or open structure and the second porous layer (5) has a small mesh count , or dense structure. A flexible abrasive member according to claim 8, characterized in that the mesh count of said second porous layer (5) is 2.5 to 6 times less than the mesh count of said first porous layer (1). A flexible abrasive member according to one of the preceding claims, wherein said layer (4) of filling material extends substantially between all deposits (2), characterized in that a layer (8) of any resin material, such as any glue material, extends along one side of said first porous layer (1) and substantially between all deposits (2). A flexible abrasive member according to claim 10, characterized in that said layer (8) of any resin material embeds at least part of said second porous layer (5). A flexible abrasive member according to one of the claims 10 or 11, characterized in that said layer (8) of any resin material is bonded to said second porous layer (5) and/or said layer (4) of filling material and/or said deposits (2). A method of making a flexible abrasive member according to any of the claims 1-12, comprising the steps of: applying electrically insulating material, i.e. a layer (4) of filling material, over selected areas of a first porous layer (1) so that in a subsequent depositing step a metal layer is deposited only over the remaining non-covered discrete areas of the surface of said first porous layer; connecting said first porous layer (1) to a cathode, by example a metal face (9) which forms the cathode in the electrolytic process; electrolytically depositing metal (2) through the pores or interstices of said first porous layer (1) causing a firm bond between the metal deposits (2) thus built up and said first porous layer (1) preferably in the presence of abrasive material (3); continuing said electrolytical deposition until metal has been deposited beyond the height of the layer (4) of filling material above the top surface of said cathode (9), causing the creation of an radial extending annular rim (10); turning said first porous layer (1) including said layer (4) of filling material and one or more deposits (2) up side down the deposit created now forming the cathode in the electrolytic process; laying a second porous layer (5), by example of mesh, non-woven or perforated sheet material, onto the free surface of said first porous layer (1); restarting the electrolytic process causing metal (12) to be deposited through the pores or interstices of said second porous layer (5) embedding at least part of said second porous layer (5) by creating relative to a deposit (2) created earlier a radial extending annular rim (10). A method of making a flexible abrasive member according to claim 13, wherein the member created is put into a reactivation bath before said step of laying the second porous layer (5) onto the free surface of the first porous layer (1), for working the surfaces of the deposits (2) created, wherein at least one surface has been connected to the cathode (9), as to prepare said surfaces for extended metal deposition (12) onto these surfaces. A method of making a flexible abrasive member according to any of the claims 1-12, comprising the steps of: applying a first porous layer (1) to a second porous layer (5) of, by example, mesh, non-woven or perforated sheet material; connecting at least one of said first (1) and said second porous layer (5) being formed as one composition to the cathode, by example a metal face (9) which forms the cathode in the electrolytic process; applying electrically insulating material, i.e. a layer (4) of filling material, over selected areas of said composition of layers (1;5) so that in a subsequent depositing step a metal layer (2) is deposited only over the remaining non-covered discrete areas of the surface of said composition of layers (1;5); electrolytically depositing metal (2) through the pores or interstices of the layers (1;5) of said composition causing a firm bond between the metal deposits (2) thus built up and said porous layers preferably in the presence of abrasive material (3); continuing said electrolytical deposition until metal (2) has been deposited beyond the height of the layer (4) of filling material above the top surface of said cathode (9), causing the creation of an radial extending annular rim (10). A method according to claim 15, wherein said composition of layers is formed by two or more at least partially interwoven or spot welded porous layers of, by example, mesh, non-woven or perforated sheet material. A method of making a flexible abrasive member according to any of the claims 13-16, wherein at least one side of the member created is applied with a layer (8) of resin, such as a glue material. A method of making a flexible abrasive member according to any of the claims 13-17, wherein said electrically insulating material, i.e. said layer (4) of filling material, is applied by way of producing a printing image including the steps of applying a photographic resist onto the surface of said first porous layer (1), exposing the resist to a film having the desired copy, development of the image thereby leaving a resist pattern, and etching of said surface to remove the resist material around the resist pattern thereby opening the first porous layer where the resist material is removed to define an etched image on said surface. A method of making a flexible abrasive member according to any of the claims 13-18, wherein said second porous layer (5) is an electrically conductive material. A method of making a flexible abrasive member according to any of the claims 13-19, wherein one side of the member created is applied with a backing layer (14), the bonding between said backing layer (14) and the member created being achieved by the layer (8) of glue material being applied earlier.

Inventors: FERRONATO SANDRO GIOVANNI GIUS, FERRONATO, SANDRO GIOVANNI GIUSEPPE
Applicants: FERRONATO SANDRO GIOVANNI GIUS, FERRONATO, SANDRO GIOVANNI GIUSEPPE
Application year: 1995
Main classification: B24D18
IPC codes: B24D3, B24D11, B23H5, B24D18