JP5706069B2 - Diamond polishing apparatus and diamond polishing method - Google Patents

Description

  The present invention relates to an apparatus and method for polishing diamond coated on an object to be polished.

  When diamonds with excellent wear resistance and lubricity are used for dies and tools (hereinafter referred to as “molds”), press working, drawing, punching, cutting, etc. can be performed without lubrication. It is not easy to make a mold from diamond. According to the chemical vapor deposition method, a diamond film can be easily formed only on a necessary portion such as a mold, but the surface roughness after coating is large, and it cannot be used unless the surface is polished smoothly.

  Polishing of the coated diamond film was performed mechanically using a grindstone or loose abrasive grains, but polishing of high-hardness diamond was difficult, requiring a lot of time for polishing and polishing accuracy. There were problems such as being unable to obtain.

  Several methods have been proposed to solve this problem. For example, Patent Documents 1 and 2 below describe a method in which a polishing tool is pressed against a diamond surface with a high load and simultaneously slid while rotating at a high speed. Patent Document 3 below describes a method of smoothing a diamond film by chemically reacting with a metal at a high temperature. Further, Patent Document 4 described below describes a method in which an ultrasonic wave is applied to a polishing tool using a metal that easily reacts with a diamond crystal, and polishing is performed while pressing the polishing tool in point contact with a surface to be polished.

Japanese Patent Laid-Open No. 2001-198833 JP-A-8-217597 JP 7-328909 A JP 2005-231022 A

  However, in the method of rotating the disks described in Patent Documents 1 and 2 at a high speed, not only the apparatus becomes complicated, but only a simple mold or the like can be polished, and a mold having a complicated shape or a minute hole, etc. Can not be polished. On the other hand, the method of polishing while applying ultrasonic waves as described in Patent Document 4 enables polishing of a mold having a complicated shape or a minute hole. However, if the diamond and the polishing tool are in a point contact state, or if the vibration frequency is low and the amplitude thereof is large, the thermochemical reaction necessary for polishing diamond having a high thermal conductivity cannot be sufficiently generated. In addition, any of the above-described methods basically only presses the polishing tool against the diamond surface, and it is difficult to control the polishing amount. In addition, it is impossible to obtain the polishing accuracy required as a mold by these methods.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a diamond polishing apparatus and a diamond polishing method capable of efficiently polishing diamond coated on an object to be polished in a short time. To do.

The diamond polishing method of the present invention includes a step of polishing the diamond surface by controlling the polishing tool to which ultrasonic waves are applied by the applying means to be brought into surface contact with the diamond surface of the object to be polished and pressed with a constant load. The application means includes an ultrasonic vibrator and a cone provided at the lower end of the ultrasonic vibrator, which is stepped and connected in two stages, and the application means has a vibration amplitude of the ultrasonic vibration. Is applied to the polishing tool so that is smaller than ½ of the length of the portion parallel to the vibration direction of the contact surface between the polishing tool and the diamond surface .

Further, the diamond polishing apparatus of the present invention includes a polishing tool for polishing a diamond surface in surface contact with a diamond surface of an object to be polished, an application means for applying an ultrasonic wave to the polishing tool, and a polishing tool with a constant load. Control means for controlling to press against the surface, the application means is provided at the lower end of the ultrasonic vibrator, a stepped and two-stage connected cone And the applying means applies ultrasonic waves to the polishing tool so that the vibration amplitude of the ultrasonic vibration is smaller than ½ of the length of the portion parallel to the vibration direction of the contact surface between the polishing tool and the diamond surface. To do .

  According to such a diamond polishing apparatus and a diamond polishing method, since the polishing tool and the diamond surface are in contact with each other by a line or a surface, the amount of heat dissipated in the vicinity of the contact portion through the diamond is relatively reduced. Further, since the polishing tool and the diamond come into contact with each other with a constant load, it is possible to supply heat in a stable state at the contact portion. As a result, the frictional heat or reaction heat generated at the contact portion between the diamond surface and the polishing tool by ultrasonic vibration can be stably generated and used efficiently. As a result, diamond can be polished efficiently in a short time. can do.

  In the diamond polishing method of the present invention, the area of the contact portion between the polishing tool and the diamond surface is preferably substantially the same as the area of the diamond surface.

  In this case, since the amount of heat dissipated in the vicinity of the contact portion through the diamond surface is reduced, the polished surface can be smoothed in a short time with high accuracy.

The diamond polishing method of the present invention preferably further includes a step of discharging polishing powder through a groove formed in the polishing tool when the diamond surface is polished.

  In this case, since the polishing powder is discharged through the groove of the polishing tool, it is possible to prevent the polishing powder from adhering in the vicinity of the polishing surface.

  The diamond polishing apparatus of the present invention preferably further includes a moving means for moving at least one of the polishing tool and the object to be polished.

  In this case, the polishing surface can be smoothed in a short time by changing the position of the polishing tool or the object to be polished.

  According to such a diamond polishing apparatus and a diamond polishing method, diamond coated on an object to be polished can be efficiently polished in a short time.

It is a mimetic diagram showing the composition of the diamond polisher concerning an embodiment. It is a mimetic diagram showing the composition of the diamond polisher concerning an embodiment. It is a top view of the ultrasonic vibration system shown in FIG. It is a side view of the ultrasonic vibration system shown in FIG. It is a photograph which shows the polished diamond surface. It is a figure which shows the state which is grind | polishing the punch with the diamond grinding | polishing apparatus shown in FIG. (A) is a graph which shows the roughness of the diamond surface before grinding | polishing, (b) is a graph which shows the roughness of the diamond surface after grinding | polishing. It is a schematic diagram which shows the structure of the diamond grinding | polishing apparatus which concerns on a modification. It is a schematic diagram which shows the structure of the diamond grinding | polishing apparatus which concerns on a modification.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant description is omitted.

  First, the structure of the diamond polishing apparatus 1 according to the embodiment will be described with reference to FIGS. 1 and 2 are schematic views showing the configuration of the diamond polishing apparatus 1. 3 and 4 are a plan view and a side view of the ultrasonic vibration system 30 shown in FIG. 1, respectively.

  The diamond polishing apparatus 1 is an apparatus for polishing diamond coated on the surface of an object to be polished. For example, although the diamond polishing apparatus 1 polishes the diamond surface such as a mold or a tool, the kind of the object to be polished is not limited, and the diamond polishing apparatus 1 can polish the diamond surface of an arbitrary member.

  The diamond polishing apparatus 1 includes a table (moving means) 10, a polishing tool 20, an ultrasonic vibration system (application means) 30, and a vibration system mounting portion (moving means) 40.

  The table 10 is a member that supports and fixes an object to be polished coated with diamond. As shown in FIG. 2, the table 10 can be rotated and tilted by driving means (not shown). The means for fixing the object to be polished is not limited to the table 10, and for example, an arm or the like may be used.

  In the example shown in FIGS. 1 and 2, the table 10 supports a die D in which a through hole Da is formed in the vertical direction. Here, the upper part of the through-hole Da is tapered upward, and a diamond coating Db is applied to the upper part by a chemical vapor deposition method.

  The polishing tool 20 is a tool for polishing the diamond coating (diamond surface) Db. The polishing tool 20 includes a shaft portion 21 extending in the vertical direction and a disk-shaped polishing portion 22 attached to the lower end of the shaft portion 21. A plurality of grooves 23 extending in the vertical direction are formed on the side surface of the polishing portion 22 at regular intervals. The groove 23 is provided for discharging polishing powder.

  The ultrasonic vibration system 30 is a device that vibrates the polishing tool 20 by applying ultrasonic waves. As shown in FIGS. 3 and 4, the ultrasonic vibration system 30 is supported and fixed by a support member (moving means) 51 extending in the vertical direction and a horizontally extending table 52 attached to the support member 51. Yes. The support member 51 is movable in the X, Y, and Z directions. Although the ultrasonic vibration system 30 is fixed in this embodiment, a portable ultrasonic vibration system that is not fixed anywhere may be used.

  The ultrasonic vibration system 30 includes an ultrasonic vibrator 31 having a piezoelectric ceramic 31a, a cone 32 screwed to the lower end of the ultrasonic vibrator 31, a horn 33 screwed to the lower end of the cone 32, And a sleeve 34. The polishing tool 20 is connected to the lower end of the horn 33 with a screw. The cone 32 is stepped to increase the amplitude, and is connected in two stages to stabilize the support. The cone 32 is attached to the sleeve 34 via a bearing (not shown). The sleeve 34 is fixed to the table 52 so as to penetrate the table 52.

  The ultrasonic vibration system 30 is moved in the vertical direction by a load control mechanism (control means) 35 attached on the table 52, thereby pressing the polishing tool 20 against the diamond coating Db with a predetermined load. The load control mechanism 35 includes an actuator 35a, a motion transmission means 35b, a load cell 35c, and a blanker 35d. The ultrasonic vibration system 30 moves in the vertical direction by transmitting the linear motion of the actuator 35a through the motion transmission means 35b. The load applied to the diamond coating Db is detected by the load cell 35c, and based on the detection result, the position of the actuator 35a is changed so as to press the polishing tool 20 against the diamond coating Db with a constant load. The blanker 35d is provided between the actuator 35a and the load cell 35c, and prevents the actuator 35a from locking.

  The ultrasonic waves are generated by flowing a high-frequency current through both ends of the piezoelectric ceramic 31 a of the ultrasonic vibrator 31 and transmitted to the polishing tool 20. Then, frictional heat is generated between the polishing tool 20 and the diamond coating Db by ultrasonic vibration, and carbon is separated from the diamond coating Db. The reason for using ultrasonic waves is that a thermochemical reaction for removing carbon from the diamond coating Db can be efficiently generated. Note that means for generating ultrasonic waves is not limited, and any device capable of obtaining high-frequency vibrations may be used.

The energy applied to the contact portion between the polishing tool 20 and the diamond coating Db is considered to have the following relationship with the applied ultrasonic conditions. The kinetic energy E per unit time due to the ultrasonic vibration is expressed by E = μP · 2πfξ. Here, μ is a friction coefficient, P is a vertical load applied to the contact surface, f is a vibration frequency, and ξ is a vibration amplitude. The sweep area S _S of the polishing tool 20 generated by oscillating with the amplitude ξ can be expressed as S _S = l · (d + 2ξ). Here, l is the length of the portion of the contact area perpendicular to the vibration direction, and d is the length of the portion parallel to the vibration direction. If d is larger than ξ, a portion where the polishing tool 20 and the diamond coating Db are always in contact is generated during ultrasonic vibration, and the area S _O is S _O = l · (d−2ξ).

Assuming that all of the kinetic energy of the polishing tool 20 is converted into thermal energy, the energy E _T per unit time effective for the thermochemical reaction by ultrasonic vibration is E _T = kS _O · μP · 2πfξ = 2πklμPf (dξ− 2ξ ² ). Here, a kS O _<1, k is a coefficient that is proportional to the amount of heat dissipated from the contact surface and the periphery thereof.

  That is, the amount of heat generated on the friction surface increases as the pressing load or the ultrasonic frequency increases, and the vibration amplitude is ½ of the length of the portion parallel to the vibration direction of the contact surface between the polishing tool 20 and the diamond coating Db. Is the largest.

  If the frequency is too high, adhesion is likely to occur and is not appropriate. The frequency is preferably about several megahertz at the maximum. On the other hand, if the amplitude is too large, the thermal efficiency is deteriorated, which is not appropriate. Although the amplitude with the best thermal efficiency is preferable, since the adhesion tends to occur when the vibration frequency is increased, the amplitude is ½ of the length of the portion parallel to the vibration direction of the contact surface between the polishing tool 20 and the diamond coating Db. It is preferable to make it smaller.

  Returning to FIG. 1, the vibration system mounting portion 40 is a portion that supports the ultrasonic vibration system 30. This vibration system mounting portion 40 is movable in the X, Y, and Z directions.

  Next, a method for polishing the diamond surface of the object to be polished using the diamond polishing apparatus 1 will be described. First, the object to be polished is placed and fixed on the table 10, and the relative position between the polishing tool 20 and the object to be polished is adjusted by moving the table 10, the vibration system mounting portion 40 or the support member 51. Subsequently, by moving the ultrasonic vibration system 30 downward by the load control mechanism 35, the polishing tool 20 to which ultrasonic waves are applied is brought into line contact or surface contact with the diamond surface of the object to be polished. Subsequently, the load control mechanism 35 is controlled to press the polishing tool 20 against the diamond surface with a constant load, thereby polishing the diamond surface. At this time, the polishing powder is discharged through a groove formed in the polishing tool.

  According to the diamond polishing apparatus 1 described above, since the polishing tool 20 and the diamond coating Db are in contact with each other by a line or surface, the amount of heat dissipated in the vicinity of the contact portion through the diamond is relatively reduced. Further, since the polishing tool 20 and the diamond are in contact with each other with a constant load, it is possible to supply heat in a stable state at the contact portion. Thereby, the frictional heat or reaction heat generated in the contact portion between the diamond coating Db and the polishing tool 20 by ultrasonic vibration can be stably generated and used efficiently, and as a result, the diamond can be efficiently used in a short time. It can be polished well. Moreover, the grinding | polishing precision required for a metal mold | die and a tool can be obtained.

  Moreover, according to this embodiment, since polishing powder is discharged | emitted via the groove | channel 23, it can prevent that polishing powder adheres in the polishing surface vicinity.

  In this embodiment, since the position of the polishing tool 20 or the object to be polished (for example, the die D) can be changed, the polishing surface can be smoothed in a short time.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to them at all.

(Example 1)
The result of polishing the diamond coating Db of the die D shown in FIG. 1 is shown in FIG. The die D fixed to the table 10 was rotated and inclined, and polishing was performed while applying a constant load to the polishing tool 20. The polishing conditions were a frequency of 27 kHz, a vibration amplitude of 10 μm _pp , a pressing load of 50 N, and a contact area of 3 mm ² . As a result, as shown in FIG. 5, the diamond coating Db was polished very smoothly. On the other hand, when the frequency, vibration amplitude, and pressing load were the same as described above, and the contact area was reduced and polishing was performed in a state close to point contact, good results as shown in FIG. 5 could not be obtained.

(Example 2)
As shown in FIG. 6, the diamond coating (diamond surface) Pa applied to the upper surface and upper side surface of the punch P was polished using the diamond polishing apparatus 1 shown in FIG. FIGS. 7A and 7B show the roughness of the diamond coating Db before and after polishing. The vertical axis of each graph in FIG. 7 represents roughness (μm), and the horizontal axis represents the horizontal range (μm) of the diamond coating Pa.

The diamond coating Pa before polishing was very rough as shown in the graph of FIG. 7A, with an arithmetic average roughness Ra = 0.589 μm and a maximum height roughness Rz = 3.079 μm. When this diamond coating Pa was polished under the conditions of a frequency of 27 kHz, a vibration amplitude of 10 μm _pp , a pressing load of 50 N, and a contact area of 3 mm ² , good results as shown in FIG. 7B were obtained. Specifically, the arithmetic average roughness Ra = 0.056 μm and the maximum height roughness = 0.365 μm, and the diamond coating Pa could be made very smooth. On the other hand, when the pressing load was 90 N without changing the frequency, vibration amplitude, and contact area, good results as shown in FIG. 7B could not be obtained.

Therefore, it is considered that the pressing load is preferably less than 90 N or less than 30 × 10 ⁶ N / m ² when the frequency is 27 kHz and the vibration amplitude is 10 μm _pp , for example, 1 to 85 N, or 3 × 10 ⁶ N / m. m ² or more and preferably less than 30 × 10 ⁶ N / m ² . The optimum pressing load varies depending on the frequency and vibration amplitude.

  The present invention has been described in detail based on the embodiments. However, the present invention is not limited to the above embodiment. The present invention can be modified in various ways as described below without departing from the scope of the invention.

  For example, as shown in FIG. 8, the diamond polishing apparatus 2 including the table 15, the polishing tool 25, and the vibration system mounting portion 45 may be used instead of the table 10, the polishing tool 20, and the vibration system mounting portion 40 in the above embodiment. Good. The table 15 is movable in the X and Y directions, and the vibration system mounting portion 45 is movable in the Z direction. The diameter of the polishing portion 25a constituting the polishing tool 25 is the same as or substantially the same as the diameter of the through hole Da of the die D. Although not shown in FIG. 8, a groove for discharging the polishing powder may be provided in the polishing portion 25a.

  Further, as shown in FIG. 9, a diamond polishing apparatus 3 including a polishing tool 26 may be used instead of the polishing tool 25 of the diamond polishing apparatus 2. The polishing portion 26a of the polishing tool 26 is processed so as to be able to contact almost the entire upper portion of the through hole Da. As a result, the area of the contact portion between the polishing tool 26 and the diamond coating Db is the same as that of the diamond coating Db. It is almost the same as the area. Although not shown in FIG. 9, a groove for discharging the polishing powder may be provided in the polishing portion 26a.

  If such a diamond polishing apparatus 2 or diamond polishing apparatus 3 is used, the amount of heat transmitted through the diamond coating Db to the vicinity of the contact portion is reduced, so that the polished surface can be smoothed in a short time with high accuracy. .

  In the diamond polishing apparatus 1, the ultrasonic vibration system 30 can move in the X, Y, and Z directions, but the means for supporting the object to be polished (for example, a table or an arm) can move in the X, Y, and Z directions. It is good. The configuration of the moving means is not limited as long as a constant load can be applied to the contact portion between the polishing tool and the diamond surface.

  1, 2, 3 ... Diamond polishing apparatus, 10, 15 ... Table (moving means), 20, 25, 26 ... Polishing tool, 22, 25a, 26a ... Polishing part, 23 ... Groove, 30 ... Ultrasonic vibration system (application) Means), 31 ... Ultrasonic vibrator, 35 ... Load control mechanism (control means), 40, 45 ... Vibration system mounting portion (moving means), D ... Dies (object to be polished), P ... Punch (object to be polished) , Db, Pa ... Diamond coating (diamond surface).

Claims (5)

A step of polishing the diamond surface by controlling the polishing tool to which the ultrasonic wave is applied by the applying means to be brought into surface contact with the diamond surface of the object to be polished and pressing it with a constant load;
The application means includes an ultrasonic vibrator, a cone provided at the lower end of the ultrasonic vibrator, stepped, and connected in two stages ,
The applying means applies ultrasonic waves to the polishing tool such that the vibration amplitude of the ultrasonic vibration is smaller than ½ of the length of the portion parallel to the vibration direction of the contact surface between the polishing tool and the diamond surface. Apply,
Diamond polishing method.   The diamond polishing method according to claim 1, wherein an area of a contact portion between the polishing tool and the diamond surface is substantially the same as an area of the diamond surface.   The diamond polishing method according to claim 1 or 2, further comprising a step of discharging polishing powder through a groove formed in the polishing tool when the diamond surface is polished. A polishing tool for polishing the diamond surface in surface contact with the diamond surface of the workpiece;
Applying means for applying ultrasonic waves to the polishing tool;
Control means for controlling the polishing tool to be pressed against the diamond surface with a constant load, and
The application means includes an ultrasonic vibrator, a cone provided at the lower end of the ultrasonic vibrator, stepped, and connected in two stages ,
The applying means applies ultrasonic waves to the polishing tool so that the vibration amplitude of the ultrasonic vibration is smaller than ½ of the length of the portion parallel to the vibration direction of the contact surface between the polishing tool and the diamond surface. Apply,
Diamond polishing equipment.   The diamond polishing apparatus according to claim 4, further comprising moving means for moving at least one of the polishing tool and the object to be polished.