Diamond polishing device and diamond polishing method

Abstract

To provide a diamond polishing device and a diamond polishing method, in which high efficiency in polishing can be achieved to reduce a running cost.SOLUTION: A diamond polishing device includes: a polishing tool 14 which polishes a diamond surface by being brought into contact with a surface of a diamond 12 which is a material to be polished and is composed of a material with low thermal conductivity; and pressing means 16 which presses the polishing tool 14 on the surface of the diamond 12 which is the material to be polished by line contact or surface contact under a constant load. High heat is generated in the surface of the diamond 12 which is the material to be polished, thereby graphitizing the surface of the diamond which is the material to be polished. In the state, the surface of the diamond 12 which is the material to be polished is polished by the polishing tool 14.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a diamond polishing apparatus and method that use polishing tools and heating means to apply high heat to the diamond, which is the material to be polished, and graphitize the diamond, thereby making polishing more efficient. [Background technology]

[0002] Conventionally, techniques have been developed for the purpose of improving efficiency in polishing diamond, such as shortening the polishing time. For example, Patent Document 1 discloses a method of polishing diamond, which is characterized in that diamond is graphitized by high heat generated by sliding a porous metal on diamond in a hydrogen atmosphere, and the graphite is then chemically reacted with hydrogen and removed.

[0003] This technology, in a polishing method that utilizes the thermochemical reaction of diamond films, makes it possible to shorten the polishing time by using porous metal to reduce the contact area with hydrogen, which is a major determining factor in the processing efficiency of polishing by thermochemical reaction, thereby enabling efficient processing of diamond. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 4-219400 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology disclosed in Patent Document 1 uses a thermochemical reaction in a hydrogen atmosphere for polishing, which results in high manufacturing and operating costs for the polishing device.In addition, the polishing technology disclosed in Patent Document 1 is difficult to adopt in fields where it is financially difficult to make a large capital investment due to the high cost of the polishing device, and generally, a polishing technology in which diamonds are rubbed together (co-rubbing polishing) is often used.

[0006] However, problems have been pointed out with diamond co-polishing technology, such as the long polishing time and the high running costs due to the wear of the diamond polishing tools.

[0007] Therefore, the problem that the present invention aims to solve is to address these problems and to provide a diamond polishing apparatus and a diamond polishing method that enable high efficiency polishing in order to reduce running costs. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides the following technical solutions. That is, the invention described in claim 1 has a grindstone made of silicon nitride ceramics, which is a material having high temperature toughness and which polishes the diamond surface of the workpiece by contacting the diamond surface with the grindstone, and a pressing means for pressing the grindstone with a constant load against the diamond surface of the workpiece in line contact or surface contact, While rotating the diamond to be polished, the grindstone is pressed against the diamond surface of the polished material with a constant load by the pressing means in line contact or surface contact; This diamond polishing device is characterized in that the surface of the diamond to be polished is graphitized by raising the temperature of the diamond to a temperature at which the surface of the diamond to be polished is graphitized, and in that state, the diamond surface of the diamond to be polished is polished by the grinding wheel.

[0009] The invention described in claim 2 is a method for polishing a diamond surface by contacting the diamond surface with a grindstone made of silicon nitride ceramics, which is a material having high temperature toughness, and a pressing means for pressing the grindstone with a constant load against the diamond surface of the polishing material in line contact or surface contact, and a heating means for heating the diamond surface of the polishing material. The temperature of the diamond to be polished is increased by the heating means, and while the diamond to be polished is rotated, the grindstone is pressed against the diamond surface of the polished material by the pressing means with a constant load in line contact or surface contact; This diamond polishing device is characterized in that the surface of the diamond to be polished is graphitized by raising the temperature of the diamond to a temperature at which the surface of the diamond to be polished is graphitized, and in that state, the diamond surface of the diamond to be polished is polished by the grinding wheel.

[0010] Ma Furthermore, claims 3 The invention described herein is as follows: or 2 The diamond polishing apparatus according to the present invention is characterized in that the polishing chips generated during polishing of the diamond surface of the polishing material are removed by the polishing chips. Grindstone The polishing surface is provided with a polishing waste discharge mechanism for discharging the polishing waste from the polishing surface.

[0011] The invention described in claim 4 is as follows: While rotating the diamond to be polished, a grinding wheel made of silicon nitride ceramics, which is a material with high temperature toughness, is pressed against the diamond surface of the polished material with a constant load in line contact or surface contact. The diamond surface is graphitized by raising the temperature to a temperature at which the diamond surface is graphitized, and in this state, The above This is a diamond polishing method characterized in that the diamond surface of the workpiece is polished with a grindstone made of silicon nitride ceramics, a material that has high temperature toughness.

[0012] The invention described in claim 5 is as follows: The temperature of the diamond to be polished is increased, and while the diamond to be polished is rotated, a grinding wheel made of silicon nitride ceramics, which is a material having high temperature toughness, is pressed against the diamond surface to be polished with a constant load in line contact or surface contact, thereby The diamond surface is graphitized by heating the diamond surface to a temperature at which the diamond surface is graphitized using a heating means. The above This is a diamond polishing method characterized in that the diamond surface of the workpiece is polished with a grindstone made of silicon nitride ceramics, a material that has high temperature toughness.

[0013] Furthermore, claims6 The invention described is as follows: 4 or 5 The method for polishing diamond described in the above, further comprising the steps of: Grindstone The present invention is characterized in that the polishing dust generated on the polishing surface is discharged from the polishing surface. Effect of the Invention

[0014] According to the diamond polishing apparatus and diamond polishing method of the present invention, high heat is generated in the material to be polished, making it possible to adjust the amount of graphitization of the material to be polished, thereby making it possible to shorten the polishing time and increase the efficiency of polishing. [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing the configuration of a first embodiment of a diamond polishing apparatus according to the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing the configuration of a second embodiment of a diamond polishing apparatus according to the present invention. [Diagram 3] 1 is a graph showing the arithmetic mean roughness of a polished material before polishing and after one hour of polishing in an experiment conducted using the first embodiment of the diamond polishing apparatus and diamond polishing method of the present invention. [Figure 4] 1 is a graph showing the maximum height roughness of a polished material before polishing and after one hour of polishing in an experiment conducted using the first embodiment of the diamond polishing apparatus and diamond polishing method of the present invention. [Diagram 5] 1 is a graph showing the arithmetic mean roughness of a polished material up to 4 hours of polishing time in an experiment conducted using the first embodiment of the diamond polishing apparatus and diamond polishing method of the present invention. [Figure 6] 1 is a graph showing the maximum height roughness of a workpiece after 4 hours of polishing in an experiment conducted using the first embodiment of the diamond polishing apparatus and diamond polishing method of the present invention. [Figure 7]1 is a graph showing the arithmetic mean roughness of a polished material up to four hours of polishing time in an experiment conducted using a second embodiment of the diamond polishing apparatus and diamond polishing method of the present invention. [Figure 8] 1 is a graph showing the maximum height roughness of a workpiece up to 4 hours of polishing time in an experiment conducted using a second embodiment of the diamond polishing apparatus and diamond polishing method of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Next, a first embodiment of a diamond polishing apparatus and a diamond polishing method according to the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram showing the configuration of a first embodiment of a diamond polishing device according to the present invention. Also, 10 denotes the diamond polishing device, 12 denotes the diamond to be polished, 14 denotes a polishing tool, 16 denotes a pressing means, and 18 denotes a heating means.

[0017] First, the theory of the efficiency of the polishing process by the diamond polishing device and diamond polishing method according to the present invention will be explained. First, it is known that diamond graphitizes at about 600 degrees in the presence of oxygen (see "Fabrication of single-crystal diamond microcomponents" JD Hunn et al. Appl. Pyhs. Lett., 65(24), pp. 3072-3074).

[0018] In other words, in diamond polishing, if the material to be polished is graphitized, the polishing tool can be made of a material harder than graphite. Therefore, it is no longer necessary to use diamond as a polishing tool, as ceramics, which are harder than graphite at high temperatures, can be used as a polishing tool, which makes it possible to reduce running costs.

[0019] In addition, diamond has a very high thermal conductivity, so when diamond is used as a polishing tool, the frictional heat input to the polishing tool is large, making it an inefficient method for graphitizing the material to be polished. On the other hand, ceramics and other materials have a low thermal conductivity, so when they are used as a polishing tool, the frictional heat generated is effective in graphitizing the material to be polished. This makes it possible to shorten the polishing time.

[0020] Here, as shown in Figure 1, the diamond polishing apparatus 10 in this embodiment has a polishing tool 14 made of a material with low thermal conductivity that polishes the surface of the diamond 12 being polished by coming into contact with the surface of the diamond, and a pressing means 16 that presses the polishing tool 14 against the surface of the diamond 12 being polished with a constant load in line contact or area contact, generating high heat on the surface of the diamond 12 being polished, and in this state, the surface of the diamond 12 being polished is graphitized by the polishing tool 14.

[0021] Furthermore, this embodiment is provided with heating means 18 for heating the diamond 12 to be polished, and this heating means 18 heats the diamond 12 to be polished, thereby raising the temperature of the diamond 12 to be polished, and in this state, the surface of the diamond 12 to be polished is polished by the polishing tool 14. Note that in this embodiment, the heating means 18 uses a heater inserted inside the cylindrical diamond 12 to be polished.

[0022] Next, the diamond polishing apparatus and the diamond polishing method in this embodiment will be described in detail. As shown in Fig. 1, in the diamond polishing apparatus 10, the diamond 12 to be polished is rotated in the direction indicated by the arrow by a rotating device (not shown).

[0023] The polishing tool 14 is pressed against the surface of the diamond 12 to be polished with a constant load by a pressing means 16 in line contact or surface contact, thereby obtaining a polishing pressure. In this embodiment, the pressing means 16 uses a spring member.

[0024] Here, if the polishing tool 14 in this embodiment is made of a material that has low thermal conductivity and high temperature toughness, it is possible to effectively suppress wear of the polishing tool 14 and to better maintain its hardness. Furthermore, if the polishing tool 14 is made of a grindstone, the polishing debris generated on the surface of the diamond 12 to be polished is properly discharged through the gaps between the abrasive grains, and the accumulation or adhesion of the polishing debris to the polishing surface can be prevented.

[0025] Next, in this embodiment, a heating means 18 for heating the diamond 12 to be polished is provided, and this heating means 18 is configured to heat the diamond 12 to be polished. In other words, the heating means 18 raises the temperature of the diamond 12 to be polished, so that the frictional heat required for graphitizing the diamond 12 to be polished is reduced. This makes it possible to improve the efficiency of polishing.

[0026] Therefore, in this embodiment, before polishing the diamond 12 to be polished with the diamond polishing tool 14, the temperature of the diamond 12 to be polished is raised in advance by the heating means 18, and the heating is maintained in the same manner during the polishing operation.

[0027] In this embodiment, the heating means 18 is inserted inside the cylindrical diamond 12 to be polished, but it may be installed externally, for example. As long as the heating efficiency is good, the location of the heating means 18 does not limit the present invention.

[0028] Next, a second embodiment of the diamond polishing apparatus and diamond polishing method according to the present invention will be described with reference to the drawings. Fig. 2 is a schematic diagram showing the configuration of a second embodiment of the diamond polishing device according to the present invention. The reference numerals are the same as those in Fig. 1, except that 20 indicates a polishing waste discharge mechanism and 22 indicates a swinging means.

[0029] As shown in Figure 2, the diamond polishing apparatus 10 in this embodiment has a polishing tool 14 made of a material with low thermal conductivity that polishes the surface of the diamond 12 being polished by coming into contact with the surface of the diamond, and a pressing means 16 that presses the polishing tool 14 against the surface of the diamond 12 being polished with a constant load in line contact or area contact.By generating high heat on the surface of the diamond 12 being polished, the surface of the diamond 12 being polished is graphitized, and in this state, the surface of the diamond 12 being polished is polished by the polishing tool 14.

[0030] Furthermore, this embodiment is provided with an abrasive waste discharge mechanism 20 having a swinging means 22 for swinging the abrasive tool 14, and by swinging the abrasive tool 14 with this swinging means 22, the abrasive waste generated by polishing is discharged from the polishing surface, and polishing can be performed while preventing the abrasive waste from accumulating or adhering to the polishing surface. In addition, it is possible to maintain the adhesion between the workpiece and the abrasive tool and the shape of the abrasive tool surface, and further to improve the efficiency of polishing.

[0031] Here, if the polishing tool 14 in this embodiment is made of a material that has low thermal conductivity and high temperature toughness, it is possible to effectively suppress wear of the polishing tool 14 and to better maintain its hardness. Furthermore, if the polishing tool 14 is made of a grindstone, the polishing debris generated on the surface of the diamond 12 to be polished is accurately discharged through the pores between the abrasive grains, and the accumulation or adhesion of the polishing debris to the polishing surface can be more effectively prevented.

[0032] In addition, the polishing machine may be configured to include a heating means 18 for heating the diamond 12 being polished, and by using this heating means 18 to heat the diamond 12 being polished, the temperature of the diamond 12 being polished is increased, thereby reducing the frictional heat required to graphitize the diamond 12 being polished.

[0033] Next, the diamond polishing apparatus and the diamond polishing method in this embodiment will be described in detail. As shown in Fig. 2, in the diamond polishing apparatus 10, the diamond 12 to be polished is rotated in the direction indicated by the arrow by a rotating member (not shown).

[0034] The diamond polishing tool 14 is pressed against the surface of the diamond 12 to be polished with a constant load by the pressing means 16 in line contact or surface contact, so that polishing pressure is obtained. In this embodiment, a spring member is used as the pressing means 16. The specifications of the diamond 12 to be polished and the polishing tool 14 in this embodiment are the same as those in the first embodiment.

[0035] (Experiment 1) Next, a diamond polishing experiment was carried out using the diamond polishing device and diamond polishing method according to the first embodiment. The diamond 12 to be polished in this experiment was cylindrical, had a diameter of 18.8 mm, and was a CVD diamond film with a roughness of Rz2.52 um (average value). The material of the polishing tool 14 was silicon nitride, which is a material with low thermal conductivity and high temperature toughness. The radius of curvature of the contact surface with the diamond 12 to be polished was 9.4 mm, the axial distance was 6 mm, and the contact area of ​​the diamond 12 to be polished was 3.01 x 6 = 18.06 mm. 2 The following formula is used:

[0036] Incidentally, diamond abrasive grains are used in the co-rubbing polishing of diamond films, but these grains wear down during polishing, changing the grain shape and contact area, so the microscopic polishing principle changes dynamically. For this reason, in this experiment, as a comparison with conventional polishing methods, instead of using diamond abrasive grains, a formed CVD diamond block was used as the polishing material and adopted as the diamond polishing tool. The diamond polishing tool was also supported by a spring (spring constant: 2.9 [Nmm -1 ]) is used to press the polishing tool against the workpiece.

[0037] In this experiment, a precision lathe (RIKEN STEEL, RBL-5) was used to rotate the workpiece. The workpiece was heated by fixing a cartridge heater with a rated capacity of 50 W inside the cylindrical workpiece, with the output controlled by the input voltage. The experimental conditions were as shown in the following table (Table 1), and the polishing speed, polishing load, and polishing time were constant.

[0038] [Table 1]

[0039] The types of experiments are as shown in the following table (Table 2). Note that experiment number 1 in the table is for a conventional co-sliding polishing in which the workpiece was not heated and the polishing tool was not cooled.

[0040] [Table 2]

[0041] In this experiment, the change in roughness of the polished material was measured for each type of experiment. The surface roughness was measured using the arithmetic mean roughness Ra [μm] and the maximum height roughness Rz [μm], and the change in roughness was evaluated using a laser microscope. The results after 1 hour of polishing are shown in Figures 3 and 4.

[0042] Next, the change in roughness after 4 hours of polishing is shown in Figures 5 and 6. For the silicon nitride tool without heated diamond film in experiment number 2, the roughness after 4 hours was greater than that of the conventional method, but the roughness was reduced compared to before polishing. This suggests that the frictional heat graphitized the diamond, which was then polished by the silicon nitride.

[0043] In experiment number 4, the diamond film was heated at 20 W and the silicon nitride tool had a roughness greater after two hours than it had been before polishing. This was because a large amount of graphite had adhered to the silicon nitride tool, and its shape was transferred to the diamond film. The maximum temperature of the entire diamond film was 91.7°C. In experiment number 3, the diamond film was heated at 10 W, and the same phenomenon as in experiment number 4 occurred after the third hour, resulting in greater roughness.

[0044] (Experiment 2) In Experiment 1, the amount of graphitization was large and the dischargeability of the polishing debris from the silicon nitride tool was low, so that graphite was adhered to the polishing surface of the tool. Therefore, in order to improve the dischargeability of the polishing debris and reduce the surface roughness, an experiment was conducted according to the second embodiment.

[0045] The material of the polishing tool was silicon nitride, and the amount of external heating of the material to be polished was 20 W. The method of oscillating the polishing tool by the oscillating means was to use the Z-axis automatic feed function of the precision lathe to oscillate the polishing tool in the ±Z-axis direction. In order to suppress the amount of graphite generation, the experiment was carried out under the polishing conditions in Table 3 below. For polishing times of 2 to 3 hours, the polishing load was reduced to 10.2 N, and for polishing times of 3 to 4 hours, the polishing load was maintained at 10.2 N while the polishing speed was reduced to 1.2 ms -1 The polishing conditions were set to reduce the surface roughness to 100 nm. The configuration of the experimental apparatus and the surface roughness measurement were the same as those in Experiment 1.

[0046] [Table 3]

[0047] Figures 7 and 8 show the change in roughness of the polished material in this experiment. The black solid line (SiN, 20W, oscillation) shows the results of the second embodiment, and the gray solid line 4 (SiN, 20W) shows the results of experiment number 4 in the first embodiment. In both Ra and Rz, the second embodiment (SiN, 20W, oscillation) had a smaller surface roughness than experiment number 4 (SiN, 20W) in the first embodiment. In addition, the adhesion of graphite to the silicon nitride polishing tool was reduced. Therefore, this method (second embodiment) shows to be an efficient polishing method. [Explanation of symbols]

[0048] 10 Diamond polishing equipment 12 Diamond as a polishing material 14 Polishing tools 16 Pressing means 18 Heating means 20 Polishing debris discharge mechanism 22 Swinging means

Claims

1. a grindstone made of silicon nitride ceramics, which is a material having high temperature toughness and which grinds the diamond surface of the workpiece by contacting the diamond surface of the workpiece; a pressing means for pressing the grindstone against the diamond surface of the workpiece with a constant load in line contact or surface contact; having This diamond polishing device is characterized in that while rotating the diamond to be polished, the pressing means presses the grinding wheel against the diamond surface of the material to be polished with a constant load in line or surface contact, and heats the diamond surface of the material to be polished to a temperature at which the diamond surface of the material to be polished is graphitized, and in that state, the diamond surface of the material to be polished is polished by the grinding wheel.

2. a grindstone made of silicon nitride ceramics, which is a material having high temperature toughness and which grinds the diamond surface of the workpiece by contacting the diamond surface of the workpiece; a pressing means for pressing the grindstone against the diamond surface of the workpiece with a constant load in line contact or surface contact; having Heating means for heating the diamond of the polishing material is provided, The heating means raises the temperature of the diamond of the polishing material, This diamond polishing device is characterized in that while rotating the diamond to be polished, the pressing means presses the grinding wheel against the diamond surface of the material to be polished with a constant load in line or surface contact, and heats the diamond surface of the material to be polished to a temperature at which the diamond surface of the material to be polished is graphitized, and in that state, the diamond surface of the material to be polished is polished by the grinding wheel.

3. The diamond polishing apparatus according to claim 1 or 2, characterized in that it is equipped with a polishing debris discharge mechanism that discharges polishing debris generated when polishing the diamond surface of the workpiece from the polishing surface of the grinding wheel.

4. A method for polishing diamond, comprising: pressing a grinding wheel made of silicon nitride ceramics, a material that has high-temperature toughness, against the diamond surface of the workpiece with a constant load and in line or area contact while rotating the diamond; heating the diamond surface to a temperature at which the diamond surface is graphitized; and polishing the diamond surface with the grinding wheel made of silicon nitride ceramics, a material that has high-temperature toughness.

5. A diamond polishing method comprising the steps of: raising the temperature of the diamond to be polished using a heating means; and, while rotating the diamond to be polished, pressing a grinding wheel made of silicon nitride ceramics, a material that has high temperature toughness, against the diamond surface to be polished with a constant load in line or surface contact, thereby raising the temperature to a temperature at which the surface of the diamond to be polished is graphitized, and in that state, polishing the diamond surface to be polished with the grinding wheel made of silicon nitride ceramics, a material that has high temperature toughness.

6. A diamond polishing method as described in claim 4 or 5, characterized in that by using a polishing debris discharge mechanism, polishing debris generated on the polishing surface of the grinding wheel while polishing the diamond surface of the polishing material is discharged from the polishing surface.

Images