The present invention relates to a method for polishing the surface of a diamond and of a diamond film, and to an apparatus for implementing the polishing method.
Properties of a diamond, which is a carbon crystal, not only include extreme hardness and superior abrasion resistance but also include superior slidability and thermal conductivity as well as a high refractive index. Due to having such properties, for example, diamonds are used as cutting tools such as a bite, an end mill, and a file, plastic working dies such as a punch and a die, sliding members such as a valve lifter and a bearing, heat dissipating members such as a heat sink, electronic substrates, and optical parts such as a lens and a window. Such diamond products are machined in accordance with their applications and are generally required to have a polished smooth surface. Applications of polished diamonds include press dies such as a die and a punch, sliding portions in a bearing, automotive parts and the like, cutting tools such as a bite and an end mill, a heat sink or an electronic substrate of electronic devices, and optical parts.
While mechanical polishing methods which also use a diamond as polishing means in the form of abrasive grains or a whetstone were adopted for polishing a diamond surface in the past, since polishing using these methods are not only time-consuming but also cause simultaneous cutting, there were problems of a short tool life and an inadequacy with respect to polishing a diamond surface that is a three-dimensional surface with irregularities instead of a flat surface.
While a polishing method disclosed in Patent Literature 1 adopts a preheating method by laser irradiation and performs polishing by causing a chemical reaction between a metal constituting a polishing member and carbon on a diamond surface, an object of this invention is to provide a diamond surface polishing method which ensures that a polishing member has a long service life, which enables the polishing member to be readily controlled, which produces a surface with high smoothness, and which is readily applicable even to polishing three-dimensional surfaces with irregularities and to provide a diamond surface polishing method which enables polishing to be performed using a polishing member formed by an inexpensive simple metal instead of using an expensive material obtained by a special production method such as an intermetallic compound. To this end, as shown in
In addition, Patent Literature 2 is a description of an invention titled “Diamond surface polishing method” previously filed as a patent application by the present applicants, the contents of which relate to a method for polishing a diamond while removing abrasive powder remaining on a surface of the diamond. Patent Literature 2 describes that this invention is a diamond surface polishing method which uses a metallic polishing member and heats the polishing member and/or a diamond surface and which polishes while removing, by rubbing, abrasive powder derived from the polishing member remaining on the diamond surface, and that preferred specific examples include: (1) when removing the abrasive powder, using at least one means selected from a group consisting of a finishing tool, a dressing tool, a shot blast, fluidic injection, electrostatic force, magnetic force, and adhesive force; and (2) when removing the abrasive powder, further using air blowing or vacuuming. According to this diamond surface polishing method, by rubbing a diamond surface being polished with a finishing tool or the like, metal powder (abrasive powder) derived from the polishing member adhering to irregularities of the diamond surface can be effectively removed and a problem of adhesion created by subjecting the abrasive powder to heat and pressure can be solved.
When polishing a diamond surface using a conventional polishing method, even if polishing is performed in a state where a polishing member is brought into contact with a surface of a polished object at a constant pressing force, there is a problem in that non-uniform polishing occurs when the contour shape of the polished object is non-uniform, such as a shape with irregularities, instead of a uniform flat shape.
Patent Literature 1: “Diamond Surface Polishing Method”, Japanese Patent Application Laid-open No. 2011-177883, published on Sep. 15, 2011
Patent Literature 2: “Diamond Surface Polishing Method”, Japanese Patent Application No. 2013-241369 (Specification), filed on Nov. 21, 2013
As a result of a thorough examination of this phenomenon carried out by the present inventors, it was found that the phenomenon is caused when a state of contact of a polished object with a polishing member changes when the polished object has a shape with irregularities instead of a uniform flat shape, in which case a difference in surface pressure of a rubbing section is created even when the polishing member is brought into contact with a constant pressing force and, in turn, a difference in a polished amount is created.
In addition, it was also discovered that, when a crystal size of diamonds on a surface of the polished object differs, a difference in a polished amount is created even when polishing is performed by bringing the polishing member into contact with the surface of the polished object at a constant pressing force.
An object of the present invention is to solve the problem described above or, in other words, to solve the problem of occurrences of non-uniform polishing or substrate exposure in a method for polishing a diamond surface of a polished object with a polishing member containing a metal or a metal oxide, and to provide a polishing method which achieves uniform polishing without being affected by a shape of the polished object.
A diamond surface polishing method according to the present invention is a diamond surface polishing method for polishing a polished object, the surface of which is made of diamond, by rubbing a polishing member having an elongated shape such as a linear or belt-like shape and containing at least a metal or a metal oxide against the diamond surface, wherein, while a polishing surface of the polished object is continuously or intermittently paid out, a pressing force of the polishing member is controlled in accordance with material properties of the polishing member and/or a shape of the polished object in a rubbing section so that contact surface pressure in a machining area becomes uniform.
In addition, in the diamond surface polishing method according to the present invention, the pressing force of the polishing member is corrected in accordance with a crystal size of a surface diamond.
A diamond surface polishing apparatus according to the present invention is a polishing apparatus including: means for holding a polished object; a polishing member having an elongated shape such as a linear or belt-like shape and containing at least a metal or a metal oxide; pressing means for pressing the polishing member toward a machining surface of the polished object; and means for causing the polishing member and the polished object to relatively move and rub against each other, the polishing apparatus further including: means for inputting and storing a shape or coordinate information of the polished object; and means for inputting or computing a pressing force to the shape of the polished object, wherein the pressing means is controlled in accordance with a prescribed pressing force that has been computed.
In addition, the means for inputting or computing a pressing force inputs or computes the pressing force so that the contact surface pressure in the machining area becomes uniform.
Furthermore, means is provided which continuously or intermittently pays out the polished object.
In addition, means is provided which rotates the means for holding the polished object.
Furthermore, the diamond surface polishing apparatus according to the present invention includes means for inputting a crystal size of a diamond, and correctively computes the prescribed pressing force in accordance with the crystal size that has been input.
With the diamond surface polishing method according to the present invention, since the pressing force of the polishing member is controlled in accordance with material properties of the polishing member and/or a shape of the polished object in the rubbing section so that contact surface pressure in a machining area becomes uniform, polishing that is free from non-uniform polishing and occurrences such as substrate exposure can be achieved without being affected by the shape of the polished object.
In addition, in the diamond surface polishing method according to the present invention, even when there is a distribution of crystal sizes in the surface diamond, since the pressing force of the polishing member is corrected in accordance with the distribution information, non-uniform polishing which occurs due to a difference in a polishing amount based on the diamond crystal size can be effectively compensated.
With the diamond surface polishing apparatus according to the present invention, since the polishing apparatus includes means for inputting and storing a shape or coordinate information of the polished object and means for computing a pressing force in accordance with a shape of the polished object so that the contact surface pressure in the machining area becomes uniform, an appropriate pressing force based on input or stored information can be applied to the polishing member, and a polishing process that is free from non-uniform polishing and occurrences such as substrate exposure can be provided without being affected by the shape of the polished object.
In addition, even with an apparatus in which a material and a shape of the polishing member are not specified but are selective, when the inputting and storing means includes a function of additionally inputting and storing information on the material and the shape of the polishing member, a function of computing an appropriate pressing force in accordance with a difference in a polishing amount due to a combination of the polishing member and the polished object can be provided and, consequently, an appropriate polishing process can be achieved.
Furthermore, with the diamond surface polishing apparatus according to the present invention in which the inputting and storing means includes, in addition to inputting a crystal size of a diamond, storing a polishing amount corresponding to a combination of a diamond particle crystal size and a polishing member as table information, and the computing means includes a function of referring to the table information and correctively computing the prescribed pressing force in accordance with a difference in a polishing amount based on a diamond crystal size, since a correction corresponding to a difference in a polishing amount based on a diamond crystal size can be made, an appropriate polishing process can also be achieved when machining a polished object with a distribution in diamond crystal sizes.
First, discovery of the problem addressed by the present invention will be described. As shown in
In addition, with a polished object with a difference in a crystal size of a surface diamond depending on location, non-uniform polishing occurs when a polishing process is performed under same conditions and the problem of substrate exposure may arise. As demonstrated by the photographs shown in
Next, a polishing state in a case where a surface of a polished object with a same diamond crystal size is polished while varying a pressing force with respect to the surface of the polished object will be examined. A test was performed involving heating the surface of the polished object by irradiating a laser (output 41 W) and, using a metal polishing member, rubbing the polished object at 100 mm/s with a prescribed pressing force in a state where a tip of the polishing member is heated to a temperature of 200° C.
Next, a fundamental technical idea of the polishing processing method according to the present invention will be described. Regarding the resolution of the problem of non-uniform polishing due to a difference in the shape of the polished object (problem 1), based on the finding described earlier in that, in accordance with the surface of a polished object having a recessed portion, a flat surface, and a protruding portion, contact areas with the polishing member are respectively large, medium, and small while surface pressures are in a reverse relationship thereof, and locations with high surface pressure are to be polished at a higher rate and a phenomenon of substrate exposure is more likely to occur, the present invention is configured to control a pressing force of the polishing member so that surface pressure of a machining area becomes uniform. In other words, in accordance with a recessed portion, a flat surface, and a protruding portion, pressing force is controlled to be small, medium, and large. An upper half of
Regarding the resolution of the problem that a polishing amount varies in accordance with a diamond crystal size on the surface of a polished object (problem 2), in consideration of the fact that the variation is caused by a property that the smaller the crystal size, the more readily the polished object is polished as described earlier, the present invention adopts a method for controlling the pressing force of the polishing member in accordance with the diamond crystal size. In other words, the pressing force of the polishing member is increased in portions with a large crystal size while the pressing force of the polishing member is reduced in portions with a small crystal size. A lower half of
A basic configuration of a control system in a polishing apparatus according to the present invention which is free of non-uniform polishing and substrate exposure is shown as a block diagram in
In this manner, while data of an appropriate pressing force corresponding to individual selection conditions is acquired and accumulated, specifically, a database is created in accordance with combinations of a material and a tip shape of the polishing member and a shape of the polished object. In addition, a plurality of samples are also prepared with respect to diamond crystal sizes, polishing amount data at a same pressing force is acquired and a relationship between a crystal size and a polishing amount is adopted as table data, and multistage table data is compiled by sequentially varying the pressing force to create a database.
Next, an example of a polishing apparatus for implementing the polishing method according to the present invention will be described.
In addition, a metallic linear member is used as the polishing member 3, a tip of the polishing unit constitutes a polishing head, and the polishing head pressing means 14 which presses the polishing head against a machining surface is also arranged on the polishing head driving means 16.
The polished object is held by polished object holding means 18 and is rotationally driven by a motor 19 so that the polished object rubs against the polishing head. Since an outer circumferential surface of the polished object work has a protruding shape and a top surface is a flat surface, polishing is performed by applying a small pressing force to the outer circumferential surface and a large pressing force to the top surface.
While the polishing member according to the present invention has been described in the present specification as a polishing member which has a metal that is easily reactive with carbon or a carburizing metal on a surface thereof and which performs chemical polishing, the polishing member is not limited thereto and can also be adapted to those of a mechanical polishing system using a diamond abrasive paper, a belt abrasive material, or a diamond wire as long as an elongated polishing member is in a mode where the polishing member is continuously or intermittently paid out and wound up.
Number | Date | Country | Kind |
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2015-046024 | Mar 2015 | JP | national |
Number | Date | Country | |
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Parent | PCT/JP2016/056528 | Mar 2016 | US |
Child | 15696491 | US |