JP6497674B2 - Plasma gas processing apparatus and method - Google Patents

Description

  The present invention relates to a technique for performing fine processing on a workpiece by using a fine tool.

  In recent years, microlenses for optical communication, molds (for example, molds having fine irregularities on the surface used in the manufacture of LED lighting devices), bio-analysis chips for μTAS (Micro-Total Analysis System), etc. In order to manufacture the substrate, there is an increasing demand for performing fine processing (micro processing) on the workpiece which is the material. In such microfabrication, fine unevenness and shape with dimensions of several hundreds of μm are formed on the work piece with a fine tool, and the surface of the work piece is finished to a mirror surface. ing.

  The fine tool is, for example, an end mill having a diameter of about 50 μm to 2000 μm. The fine tool is made of, for example, polycrystalline diamond. Polycrystalline diamond tools are widely used because they are free of cleavage and hardness anisotropy, have chemical stability, and are less expensive than single crystal diamond tools. In recent years, in particular, while processing the above-mentioned fine shape on a work piece of a hard and brittle material such as cemented carbide or ceramics, using a polycrystalline diamond fine tool made of fine diamond having a particle diameter of 0.5 μm to 1 μm. It has been confirmed that the processed surface can be finished into a mirror surface having an average roughness Ra of 4 nm or less.

  In addition, there exists the following patent document 1 as a prior art document of this application, for example. This document describes a fine tool made of polycrystalline diamond.

JP 2008-229664 A

  In the future, the following two points (1) and (2) will be important in order to improve the precision of micromachining (ultra-precision machining) for workpieces and fine tools of a wide range of materials.

(1) Cooling effect improvement When processing a workpiece while cooling the workpiece, the cooling performance of the workpiece is improved. By improving the cooling performance of the workpiece, the processing performance of the fine tool is maximized. For example, the wear of the fine tool can be prevented by improving the cooling performance at the boundary between the fine tool and the workpiece.
(2) Tool surface condition improvement During machining of a workpiece, the chip of the workpiece or its reaction product is prevented from adhering to the fine tool. Thereby, the fine surface shape of the fine tool is maintained without being changed during processing. That is, the same fine tool can be used for a long time without lowering the processing performance.

  Accordingly, an object of the present invention is to improve the cooling performance of a workpiece when machining the workpiece while cooling the workpiece, and to prevent chips or reaction products from adhering to the fine tool. It is an object of the present invention to provide an apparatus and method capable of achieving the above.

In order to achieve the above-mentioned object, according to the present invention, a processing machine having a micro tool for performing micro processing on a workpiece, and cooling for supplying a coolant to a processing point to be micro processed by the micro tool in the workpiece. A plasma gas processing apparatus that includes a liquid supply device and uses a plasma gas during the fine processing,
There is provided a plasma gas processing apparatus comprising a plasma gas supply device for supplying a plasma gas to the processing point.

  The plasma gas utilization processing apparatus of this invention is comprised as follows, for example.

The surface of the workpiece is formed of silicon carbide,
The plasma gas supply device oxidizes silicon carbide forming the surface of the workpiece by supplying plasma gas to the surface region of the workpiece including the processing point, and forms the surface. From silicon carbide to silicon dioxide.

The plasma gas supply device
A pair of electrodes to which a potential difference is applied;
A plasma generation gas supply device for supplying a plasma generation gas to a discharge region between the pair of electrodes;
When the plasma generation gas is supplied to the discharge region, a potential difference is applied between the pair of electrodes, whereby a discharge is generated between the pair of electrodes through the discharge region, and the plasma gas is generated from the plasma generation gas. The generated plasma gas supply device supplies the generated plasma gas to the processing point.

  The plasma gas supply device has a gas nozzle for injecting plasma gas at a processing point.

Moreover, in order to achieve the above-mentioned object, according to the present invention, there is provided a plasma gas utilization processing method using a plasma gas when performing fine processing on a workpiece,
When processing a workpiece with a fine tool, a coolant is supplied to a processing point of the workpiece with a fine tool by a coolant supply device, and a plasma gas is supplied to the processing point by a plasma gas supply device. A processing method using plasma gas is provided.

Preferably, in the above plasma gas utilization processing method, the surface of the workpiece is formed of silicon carbide,
By supplying plasma gas to the surface region of the workpiece including the processing point, the silicon carbide that forms the surface of the workpiece is oxidized, and the material that forms the surface is changed from silicon carbide to silicon dioxide. Change.

  According to the above-described present invention, when the workpiece is processed by the fine tool, the coolant supply device supplies the coolant to the processing point of the workpiece by the fine tool, and the plasma gas supply device Plasma gas can be supplied to the point. As a result, the following effects (A) and (B) or the following effects (A) to (C) can be obtained.

(A) The hydrophilicity of the workpiece surface is improved. By supplying the plasma gas to the surface region of the workpiece including the processing point, the active species (for example, OH radical, N ₂ radical) in the plasma gas are decorated (existing) in the surface region of the workpiece. ) State. The active species in the plasma gas have a very high reactivity, so they immediately cause oxidation-reduction reactions with other atoms and molecules to become stable. Therefore, the hydrophilicity of the surface of the workpiece decorated with the active species is significantly improved. As a result, the cooling performance at the boundary between the fine tool and the workpiece is improved.

  In addition, in this application, hydrophilicity means that the familiarity (adsorption property) with a cooling fluid (oil, water, or a liquid mixture of oil and water) is remarkably high.

(B) The surface of the fine tool is in a state in which chips are difficult to adhere. The plasma gas is also supplied to the surface area of the micro tool near the machining point, so that the active species in the plasma gas is decorated (exists) on the surface area of the micro tool near the machining point. Become. Therefore, the hydrophilicity of the surface of the fine tool is remarkably improved. As a result, the coolant reaches the unevenness of several micron level on the surface of the fine tool (for example, rotating at high speed), so high lubricity can be secured over a wide range of the surface of the fine tool, and chips adhere. It becomes difficult to do.

(C) Chips of the workpiece have changed to a substance that is difficult to adhere to the fine tool. As described above, an active species (for example, OH radical) in the plasma gas is decorated (existing) in the surface region of the workpiece including the processing point. As a result, the active species reacts with the workpiece or the chips thereof, so that the surface layer portion of the workpiece or the chips thereof becomes a reactant that is difficult to adhere to the fine tool. Therefore, the fine surface shape of the fine tool is maintained without change during processing.

  The above effects (A) and (B) or effects (A) to (C) are superimposed, and fine processing superior to the conventional one is realized. For example, the surface roughness of the processed surface of the workpiece can be reduced to about 1 nm or less, wear of the fine tool can be suppressed, and the sharpness of the fine tool can be maintained for a long time.

1 shows a plasma gas processing apparatus according to an embodiment of the present invention. The plasma gas supply apparatus provided in the plasma gas utilization processing apparatus of FIG. 1 is shown. 1 shows an entire plasma gas processing apparatus according to an embodiment of the present invention. It is the image of the end mill obtained by the scanning electron microscope (SEM). The surface roughness of the processed surface by the Example and comparative example of this invention is shown. It is a SEM image of a fine tool after processing of an example of the present invention and a comparative example. It is an energy spectrum obtained by X-ray photoelectron spectroscopy with respect to the workpiece surface. It is an image which shows the hydrophilic property of the workpiece surface. Each wavelength component of the light of the plasma gas currently emitted is shown. The abrasion amount of the fine tool in the Example of this invention and a comparative example is shown.

  A preferred embodiment of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

  FIG. 1 shows a plasma gas utilizing processing apparatus 10 according to an embodiment of the present invention. The plasma gas processing apparatus 10 supplies a cooling liquid to a processing machine 20 that performs micromachining on the workpiece 1 using the fine tool 3 and a processing point Pm that is micromachined by the processing machine 20 on the workpiece 1. A cooling liquid supply device 5 and a plasma gas supply device 7 for using a plasma gas at the time of fine processing are provided.

The processing machine 20 has a fine tool 3 for finely processing the workpiece 1 at a processing point Pm in the atmosphere. That is, the processing point Pm is located in the atmosphere. The fine tool 3 has a dimension (for example, a diameter) of 6000 μm or less. In this embodiment, the fine tool 3 is an end mill having a tip having a diameter of about 50 μm to 1000 μm (or 50 μm to 2000 μm). The fine tool 3 is used to form a fine structure (for example, a depression) of about 50 μm to several hundred μm on the workpiece 1, for example.
The workpiece 1 is formed of silicon carbide (SiC) in the present embodiment, but may be formed of other materials. That is, the present invention can be applied to fine processing of the workpiece 1 that is, for example, a hard and brittle material (silicon, quartz, sapphire, silicon nitride, zirconia, cemented carbide, high grade stainless steel, etc.).

  In a preferred example, the fine tool 3 is made of polycrystalline diamond. The polycrystalline diamond fine tool 3 is suitable for processing the work 1 of a hard and brittle material. This is because polycrystalline diamond does not cleave with respect to hard and brittle materials, has no hardness anisotropy, and has high chemical stability. However, according to the present invention, the material of the fine tool 3 is not limited to polycrystalline diamond, and may be other materials. For example, the fine tool 3 is a tool made of single crystal diamond, a tool with a diamond coating on the surface (diamond coated tool), a tool made of cubic boron nitride (cBN), or a diamond that does not contain a binder (binder). It may be a polycrystalline tool (binderless polycrystalline diamond tool).

  Other components of the processing machine 20 will be described later.

  When the workpiece 1 is being processed by the fine tool 3, the coolant supply device 5 is a processing point Pm by the fine tool 3 in the workpiece 1 (more specifically, the surface of the workpiece 1 including the processing point Pm). The coolant is supplied to the local region and the tip of the fine tool 3 including the processing point Pm. In FIG. 1, the coolant supply apparatus 5 includes a coolant tank 5a, a pump 5b, a coolant pipe 5c, and a coolant nozzle 5d. The coolant tank 5a stores coolant. When the pump 5b is operated, the coolant in the coolant tank 5a is supplied to the coolant nozzle 5d through the coolant pipe 5c. The coolant nozzle 5d mists the coolant supplied from the coolant tank 5a and injects it to the processing point Pm. That is, the coolant nozzle 5d supplies a mist coolant to the processing point Pm. The cooling liquid is, for example, oil, water, or a mixed liquid of oil and water. When the cooling liquid is water, the cooling liquid preferably contains a water-soluble surfactant in addition to water. In this case, the cooling liquid may further contain a preservative and a colorant.

The plasma gas supply device 7 supplies a plasma gas to the processing point Pm. As a result, the active species (for example, OH radicals and N ₂ radicals) in the plasma gas are decorated (existing) in the surface region of the workpiece 1. Thereby, the hydrophilicity of the surface of the workpiece 1 is improved, and the cooling liquid spreads along the surface of the workpiece 1 without being a droplet on the surface of the workpiece 1. As a result, the cooling performance at the boundary (working point) between the fine tool 3 and the workpiece 1 is improved.

In a preferred example, the workpiece 1 is made of silicon carbide (SiC). In this case, when the plasma gas supply device 7 supplies the plasma gas to the surface region of the workpiece 1 including the processing point Pm, the active species having an oxidizing power in the plasma gas (especially, OH radicals) are exposed. The silicon carbide (SiC) that forms the surface of the workpiece 1 is oxidized to change the material that forms the surface from silicon carbide (SiC) to highly hydrophilic silicon dioxide SiO ₂ . Accordingly, the hydrophilicity of the surface of the workpiece 1 is further improved, and the cooling performance at the boundary (processing point) between the fine tool 3 and the workpiece 1 is further improved.

  The configuration of the plasma gas supply device 7 is shown in FIG. 2A is a cross-sectional view taken along the line AA in FIG. 2B, and FIG. 2B is a cross-sectional view taken along the line BB in FIG. 2A.

  The plasma gas supply device 7 includes a power source 7a, a pair of electrodes 7b and 7c, and a plasma generation gas supply device 7d. The power supply 7a applies a potential difference to the pair of electrodes 7b and 7c. The plasma generating gas supply device 7d supplies the plasma generating gas to the discharge region R between the pair of electrodes 7b and 7c. With this configuration, when the plasma generating gas is supplied to the discharge region R, the power source 7a applies a potential difference between the pair of electrodes 7b and 7c, thereby causing the discharge region between the pair of electrodes 7b and 7c. Discharge occurs through R, and plasma gas is generated from the plasma generating gas. The plasma gas supply device 7 supplies the generated plasma gas to the processing point Pm.

  In one example, the plasma generating gas is composed of only a discharge gas (for example, nitrogen or argon) that assists plasma generation. In another example, the plasma generating gas contains 90% or more of the above-mentioned discharge gas by volume ratio, and the rest includes a reactive gas (for example, oxygen) that enhances the cooling effect.

  The plasma gas supply device 7 includes a gas nozzle 7e that injects the plasma gas generated as described above to a processing point Pm as a plasma gas jet.

  In addition, the plasma gas supply device 7 has a case 7f provided with the gas nozzle 7e described above at the tip. The case 7f has the above-described discharge region R therein. The case 7f is formed of a dielectric (for example, quartz). The inside of the case 7f is airtight with respect to the outside except for the tip opening 7e1 of the gas nozzle 7e. In the example of FIG. 2, one electrode 7b is disposed at the center of the case 7f, and the other electrode 7c is disposed on the inner peripheral surface of the case 7f. One electrode 7b is supported by an insulating member 7g fixed to the case 7f. A conducting wire 7h connecting one electrode 7b and the power source 7a passes through the inside of the insulating member 7g. The conducting wire 7h is provided with a switch 7i. The other electrode 7c may be grounded.

  The plasma generation gas supply device 7d includes a gas tank 7d1 that stores a plasma generation gas (for example, nitrogen gas), and a gas pipe 7d2 that supplies the plasma generation gas from the gas tank 7d1 to the inside of the case 7f. The gas pipe 7d2 may be provided with a valve 7j (for example, a flow rate adjusting valve or an on-off valve).

  FIG. 3 is a diagram illustrating the entire plasma gas utilization processing apparatus 10. As shown in FIG. 3, the processing machine 20 of the plasma gas utilization processing apparatus 10 includes the fine tool 3, the tool support 9, the table 11, the first drive device 13, the nozzle support 15, and the second drive device. 17 and a control device 19.

When the fine tool 3 is an end mill, the end mill 3 is rotationally driven by a rotational drive device 8 (air turbine spindle) when cutting the machining point Pm in the workpiece 1.
The tool support 9 supports the fine tool 3. In the present embodiment, the fine tool 3 is an end mill, and the tool support 9 supports the end mill 3 in a rotatable manner. That is, the end mill 3 is supported by the tool support 9 so as to be rotatable about its own central axis.
The workpiece 1 is attached to the base 11. In the example of FIG. 3, the workpiece 1 is fixed to the table 11 with a jig 12.

  The first driving device 13 drives one or both of the tool support 9 and the base 11. In FIG. 3, the first driving device 13 includes a tool side driving unit 13 a that drives the tool support 9 and a table driving unit 13 b that drives the table 11. You may be comprised by one among the parts 13b. The first drive device 13 drives one or both of the tool support 9 and the table 11, whereby the fine tool 3 supported by the tool support 9 and the workpiece 1 attached to the table 11 are relative to each other. Change position. As a result, the fine tool 3 is moved to the machining point Pm on the workpiece 1, the workpiece 1 is cut at the machining point Pm, and the machining point Pm by the fine tool 3 is further cut in the workpiece 1. Move. That is, the workpiece 1 is processed at the processing point Pm while the processing point Pm continuously moves.

  Although the detailed illustration is omitted in FIG. 3, the tool side drive unit 13a drives the tool support 9 in at least one of the X axis, the Y axis, and the Z axis shown in FIG. You may have the structure to do. Moreover, the tool side drive part 13a may have the structure which rotationally drives the tool support body 9 around a predetermined axis | shaft (for example, axis | shaft of a Y-axis direction). Similarly, the table drive unit 13b may have a configuration for driving the table 11 in at least one of the X-axis, Y-axis, and Z-axis directions. Further, the table driving unit 13b may have a configuration for rotating the table 11 around a predetermined axis (for example, an axis in the Y-axis direction).

  The nozzle support 15 supports the coolant nozzle 5d and the gas nozzle 7e. That is, the coolant nozzle 5d is attached to the nozzle support 15 in the direction and position where the coolant can be sprayed to the processing point Pm. Similarly, the gas nozzle 7e is attached to the nozzle support 15 in such a direction and position that the plasma gas can be injected to the processing point Pm.

  The second driving device 17 drives the nozzle support 15 to move the nozzle support 15 in accordance with the movement of the processing point Pm in the workpiece 1. Thereby, even if the position of the processing point Pm changes, the cooling liquid nozzle 5d can inject the cooling liquid to the processing point Pm, and the gas nozzle 7e can inject plasma gas to the processing point Pm.

  The control device 19 controls the first drive device 13 and the second drive device 17. Further, the control device 19 controls the injection of the coolant from the coolant nozzle 5d to the processing point Pm by controlling the operation of the pump 5b (see FIG. 1). Furthermore, the control device 19 controls the opening / closing or opening of the valve 7j (see FIG. 1) by controlling the opening / closing of the switch 7i (see FIG. 2), and thereby plasma from the coolant nozzle 5d to the processing point Pm. Control gas injection.

  In the plasma gas utilization processing method according to the embodiment of the present invention, the workpiece 1 is cut using the plasma gas utilization processing apparatus 10 having the above-described configuration. In this method, when the fine tool 3 is cutting a processing point Pm in the workpiece 1 (hereinafter, also simply referred to as processing), the coolant supply device 5 supplies the coolant to the processing point Pm. The plasma gas supply device 7 supplies plasma gas to the processing point Pm. In FIG. 1, at the time of processing, the coolant nozzle 5d of the coolant supply device 5 injects coolant (for example, mist-like oil) to the processing point Pm, and the gas nozzle 7e of the plasma gas supply device 7 generates plasma gas. It sprays on the processing point Pm.

During processing, active species (OH radicals, N ₂ radicals, etc.) in the plasma gas are supplied (injected) to the processing point. The OH radical is obtained by dissociating moisture from the gas pipe 7d2 and moisture in the atmosphere by electrons in the plasma gas. The N ₂ radical is due to the nitrogen molecule N ₂ of the plasma generating gas.

In this method, when the surface of the workpiece 1 (for example, the entire workpiece 1) is formed of silicon carbide (SiC), when the plasma generating gas passes through the discharge region R, the pair of electrodes 7b, By generating a discharge through the discharge region R between 7c, this plasma generating gas is changed to a plasma gas, and this plasma gas is supplied to the processing point Pm. Thereby, the silicon carbide (SiC) on the surface of the workpiece 1 reacts with the active species (particularly OH radicals) having the oxidizing power in the plasma gas and changes to silicon dioxide (SiO ₂ ).

The control device 19 controls the first driving device 13 and the second driving device 17 as well as the cooling liquid supply device 5 and the plasma gas supply device 7 so as to obtain such an operation.
That is, at the time of starting the processing of starting the processing of the workpiece 1 by bringing the fine tool 3 into contact with the workpiece 1 from the state where the fine tool 3 is not in contact with the workpiece 1, the control device 19 performs the first operation. By controlling the driving device 13, the fine tool 3 comes into contact with the position to be processed in the workpiece 1. Thereby, this position becomes the processing point Pm, and the fine tool 3 cuts the workpiece 1 at the processing point Pm. Further, at the start of processing, the control device 19 controls the second driving device 17 so that the coolant nozzle 5d can spray the coolant to the processing point Pm and the gas nozzle 7e can spray the plasma gas to the processing point Pm. The nozzle support 15 is moved to the left. Further, at the start of processing, the control device 19 operates the pump 5b to inject the coolant from the coolant nozzle 5d to the processing point Pm. Further, at the start of processing, the control device 19 opens the valve 7j and closes the switch 7i, so that the plasma generating gas is supplied to the discharge region R between the pair of electrodes 7b and 7c, and a pair of power sources 7a. A voltage is applied to the electrodes 7b and 7c, and a discharge occurs between the pair of electrodes 7b and 7c in the discharge region R. Therefore, the plasma generating gas becomes plasma gas in the discharge region R, and this plasma gas is injected from the gas nozzle 7e to the processing point Pm.

  After the start of machining, the control device 19 controls the first drive device 13 to change the relative position between the fine tool 3 and the workpiece 1 and move the machining point Pm on the workpiece 1. . Along with this movement, the control device 19 controls the second drive device 17 so that the coolant nozzle 5d continuously injects coolant to the processing point Pm, and the gas nozzle 7e continues to plasma. Gas is injected to the processing point Pm. Even if the processing point Pm moves, the control device 19 is configured so that the coolant and the plasma gas are injected to the processing point Pm as described above until the processing of the workpiece 1 by the processing machine 20 is completed. The operation of the pump 5b is continued, the valve 7j is opened, and the switch 7i is closed.

  An embodiment in which the workpiece 1 is cut using the above-described plasma gas utilization processing apparatus 10 will be described.

The plasma gas conditions were as follows.
Gas used: Nitrogen gas was used as a plasma generating gas.
Gas flow rate: Plasma gas was injected to the processing point Pm at a plasma gas flow rate of 20 LM.
Irradiation range: Plasma gas was irradiated (injected) to a processing point Pm in a region having a radius of about 5 mm on the surface of the workpiece 1.
Discharge method: Atmospheric pressure glow discharge was adopted as a discharge type between the pair of electrodes 7b and 7c.
Applied voltage: A potential difference of 8 kV at a frequency of 50 Hz was applied between the pair of electrodes 7b and 7c by a power source 7a of AC 100V.
Case 7f: Case 7f in FIG. 2 was formed into a cylindrical shape having a diameter of 8 mm, and the material thereof was quartz.

The processing conditions were as follows.
Workpiece 1: Workpiece 1 was a bulk material of high-purity silicon carbide (SiC having a purity of 99.9995% or more) formed by chemical vapor deposition. The dimensions of this bulk material are 10 mm long × 10 mm wide × 5 mm high.
Feeding speed: The moving speed of the processing point Pm was set to 5 mm / min.
Tool rotation speed: The rotation speed of the end mill 3 was set to 50000 rpm.
Coolant: Oil (non-chlorine oil-based water-insoluble oil) was mist as a coolant and sprayed to the processing point Pm.

  A fine tool 3 shown in FIG. 4 was used. FIG. 4 is an image of the end mill 3 obtained by a scanning electron microscope (SEM). In FIG. 4, the upper left image is an enlarged view of a portion surrounded by a broken line (tip end portion of the end mill 3) in the lower right end mill 3 image. The tip of the end mill 3 in FIG. 4 is formed of polycrystalline diamond. The diameter of the end of the endle is about 200 μm (0.2 mm). As shown in FIG. 4, the end portion of the endl has a two-blade shape.

A specific processing method is as follows.
As an example of the present invention, milling was performed using the plasma gas processing apparatus 10 under the above-described conditions to form a number of grooves having a depth of 25 μm on the surface of the workpiece 1.
As a comparative example, a plasma gas is not injected to the processing point Pm, and other conditions are the same as in the above-described embodiment, and milling is performed to form a large number of grooves with a depth of 25 μm on the surface of the workpiece 1 did.

  The results of the examples of the present invention and the results of the comparative examples are as follows.

(Roughness of the processed surface)
The arithmetic average surface roughness and the maximum height roughness were measured as the surface roughness of the processed surface (bottom surface of the groove) processed in the workpiece 1.

FIG. 5A shows the average surface roughness of the machined surface according to the example of the present invention and the comparative example. In FIG. 5A, the horizontal axis indicates the total distance (hereinafter referred to as the processing distance) at which the workpiece 1 is processed from the processing start time, and the vertical axis indicates the measurement of the arithmetic average surface roughness Ra of the processing surface. Indicates the value. In FIG. 5A, the mark ♦ is a measured value in the case of the present example, and the mark ■ is a measured value in the comparative example.
As can be seen from FIG. 5A, in this example, even when the processing distance is 3000 mm, the surface roughness Ra of the processed surface does not deteriorate from the surface roughness at the start of processing. That is, in this embodiment, the surface roughness Ra of the processed surface is maintained at a low value (a value within the range of 0.7 nm to 2.1 nm) regardless of the processing distance. On the other hand, in the comparative example, the value of the surface roughness Ra of the processed surface gradually increases as the processing distance increases from the start of processing, and at the processing distance of 3000 mm, the surface roughness Ra of the processed surface is 6.0 nm. Is getting worse.
Further, as can be seen from FIG. 5 (A), it can be expected to obtain a high-quality processed surface having an arithmetic average surface roughness of 1 nm or less by the plasma gas utilizing processing apparatus 10 of the present invention.

FIG. 5B shows the peak-to-valley surface roughness of the processed surface according to the example of the present invention and the comparative example. In FIG. 5B, the horizontal axis represents the machining distance, and the vertical axis represents the measured value of the maximum height roughness Rz of the machined surface. In FIG. 5B, the mark ♦ is a measured value in this example, and the mark ■ is a measured value in the comparative example.
As can be seen from FIG. 5B, in this example, even when the machining distance is 3000 mm, the maximum height roughness Rz of the machining surface is not deteriorated from the maximum height roughness Rz at the time of machining start. . On the other hand, in the comparative example, when the processing distance is 2400 mm or more, the maximum height roughness Rz is greatly deteriorated to be larger than 200 nm, and when the processing distance is 2900 mm, it is larger than 1000 nm because cracks are generated on the processing surface. It has become.

(Presence or absence of deposits on end mill)
FIG. 6A is an image obtained by observing the tip of the end mill 3 with an SEM when the above-described working distance is 1000 mm in the example of the present invention. FIG. 6B is an image obtained by imaging the tip of the end mill 3 with the SEM when the above-described processing distance is 1000 mm in the comparative example. In each figure, the image on the right side is an enlarged view of a portion surrounded by a broken line in the image on the left side, and the bar graph is a point of the figure by an energy dispersive X-ray spectrometer (EDS). The analysis result of the element ratio (atomic percent) obtained by A or Point B is shown.
In this example, as shown in FIG. 6A, no deposits derived from the chips of the workpiece 1 were observed on the surface of the edge portion that acts as a cutting blade at the tip of the end mill 3. . On the other hand, in the comparative example, as shown in FIG. 6B, the surface of the edge portion that acts as a cutting blade at the tip of the end mill 3 has a film shape derived from the chips of the workpiece 1 (SiC). The deposit (Si) was adhered. As described above, the plasma gas injection to the processing point Pm has a remarkable effect in preventing the substance (Si) derived from the chips of the workpiece 1 from adhering to the end mill 3.

(Hydrophilicity of workpiece surface)
As described below, in this example, the hydrophilicity of the surface of the workpiece 1 was improved by the plasma gas.
In order to investigate the effect of plasma gas injection on the processing point Pm in the workpiece 1 (that is, the improvement in hydrophilicity of the surface of the workpiece 1), in the embodiment described above, X-ray photoelectron spectroscopy (X-ray Photoelectron Spectroscopy) is used. : XPS), the elemental composition of the surface of the workpiece 1 was analyzed.
FIG. 7A shows a case before the plasma gas is injected onto the workpiece 1, and FIG. 7B shows a case after the plasma gas is injected onto the workpiece 1. In FIG. 7A, in the energy spectrum obtained by XPS, a peak occurs only at the position of the black circle corresponding to SiC, whereas in FIG. 7B, the binding energy corresponding to SiC is shown. A peak occurs in the energy spectrum not only at the black circle position but also at the white circle position of the binding energy corresponding to SiO ₂ . Therefore, it can be seen that only the surface layer of the workpiece 1 was oxidized by injecting the plasma gas onto the surface of the workpiece 1. Specifically, by injecting plasma gas onto the workpiece 1 that is SiC, only the surface layer of SiC in the workpiece 1 was oxidized, and SiO ₂ exhibiting excellent hydrophilicity was formed.

FIG. 8 is an image showing the hydrophilicity of SiO ₂ . FIG. 8A shows a state in which droplets are dropped on the surface of the workpiece 1 before the plasma gas is jetted onto the workpiece 1 in the above-described embodiment. FIG. 8B shows a state where droplets are dropped on the surface of the workpiece 1 after the plasma gas is sprayed onto the workpiece 1 in the above-described embodiment. As can be seen from FIG. 8, after the plasma gas is injected, the active species (OH radical and N ₂ radical) in the plasma gas are decorated on the surface of the workpiece 1 and the workpiece 1 (SiC) Since SiO ₂ having high hydrophilicity is formed on the surface, the liquid spreads on the surface of the workpiece 1 to the extent that droplets cannot be confirmed. As described above, when the plasma gas is sprayed on the surface of the workpiece 1, the coolant sprayed on the surface of the workpiece 1 spreads along the surface of the workpiece 1, so that the boundary between the fine tool 3 and the workpiece 1 is reached. The cooling effect by the coolant can be improved.

Incidentally, in the plasma gas, it contains the OH radicals and N ₂ radicals, as follows, was confirmed by the measurement with a spectroscope.
The plasma gas from the gas nozzle 7e emits light, and each wavelength component of this light was measured with a spectroscope. The measurement results are shown in FIG. 9, the peak at a wavelength corresponding to the OH radicals and N ₂ radicals is generated, the plasma gas, it can be seen that contains OH radicals and N ₂ radical.

(Tool wear)
FIG. 10 shows the amount of wear of the fine tool 3 in the example of the present invention and the comparative example. In FIG. 10, the horizontal axis indicates the machining distance, and the vertical axis indicates the amount of wear of the fine tool 3. In FIG. 10, the mark ◆ is a measured value in the case of the present example, and the mark ■ is a measured value in the comparative example.
As can be seen from FIG. 10, in this example, it can be seen that the wear amount of the fine tool 3 is suppressed as compared with the comparative example. That is, when the working distance was 1000 mm, the wear amount in the comparative example was about 1.31 μm, whereas the wear amount in the present example was about 0.77 μm.

  According to the above-described embodiment of the present invention, when the workpiece 1 is being processed by the fine tool 3, the coolant supply device 5 supplies the coolant to the processing point Pm of the workpiece 1 by the fine tool 3. At the same time, the plasma gas supply device 7 can supply the plasma gas to the processing point Pm. As a result, the following effects (A) and (B) or the following effects (A) to (C) can be obtained.

(A) The hydrophilicity of the surface of the workpiece 1 is improved. By supplying the plasma gas to the surface region of the workpiece 1 including the processing point Pm, active species (for example, OH radical, N ₂ radical, ozone) in the plasma gas are decorated on the surface region of the workpiece 1. (There is an existing state). The active species in the plasma gas have a very high reactivity, so they immediately cause oxidation-reduction reactions with other atoms and molecules to become stable. Therefore, the hydrophilicity of the surface of the workpiece 1 decorated with active species is significantly improved. As a result, the cooling performance at the boundary between the fine tool 3 and the workpiece 1 is improved.

(B) The surface of the fine tool 3 is in a state where chips are difficult to adhere. By supplying the plasma gas also to the surface region of the fine tool 3 near the processing point Pm, the active species in the plasma gas is decorated in the surface region of the fine tool 3 near the processing point Pm (existing). ) State. Therefore, the hydrophilicity of the surface of the fine tool 3 decorated with active species is remarkably improved. As a result, since the coolant reaches the unevenness of several micron level on the surface of the fine tool 3 (for example, rotating at high speed), high lubricity can be secured over a wide range of the surface of the fine tool 3, and chips are removed. Becomes difficult to adhere. This makes it possible to smoothly discharge the chips from the surface of the workpiece 1.

(C) The chips of the workpiece 1 are changed to a substance that is difficult to adhere to the fine tool 3. As described above, the active region (for example, OH radical, N ₂ radical) in the plasma gas is decorated (existing) in the surface region of the workpiece 1 including the processing point Pm. As a result, the active species reacts with the workpiece or the chips thereof, so that the surface layer portion of the workpiece 1 and the chips thereof become a reactant that is difficult to adhere to the fine tool 3. Therefore, the fine surface shape of the fine tool 3 is maintained without changing during processing.

  The above effects (A) and (B) or the above effects (A) to (C) are superimposed, and fine processing superior to the conventional technique is realized. For example, the surface roughness of the processed surface of the workpiece 1 can be about 1 nm or less, wear of the fine tool 3 can be suppressed, and the sharpness of the fine tool 3 can be maintained for a long time.

Further, when the surface of the workpiece 1 is formed of silicon carbide (SiC), the hydrophilicity of the surface of the workpiece 1 is further improved as follows.
When the plasma gas supply device 7 supplies the plasma gas to the surface region of the workpiece 1 including the processing point Pm, the workpiece is processed by the oxidizing power of the active species (especially OH radical or ozone) in the plasma gas. The silicon carbide (SiC) that forms the surface of the object 1 is oxidized. That is, in the workpiece 1, the surface layer portion including the surface of the workpiece 1 is silicon dioxide (SiO ₂ ). Silicon dioxide exhibits excellent hydrophilicity. Accordingly, the hydrophilicity of the surface of the workpiece 1 is further improved, and the cooling performance at the boundary between the fine tool 3 and the workpiece 1 is further improved. As a result, wear of the fine tool 3 can be further suppressed.

  The present invention is not limited to the above-described embodiment, and various changes can be made without departing from the scope of the present invention.

For example, the coolant supply device 5 may be configured to supply the coolant to the processing point Pm, and may have a configuration other than the configuration described above. In this case, other points may be the same as described above, or may be changed as appropriate.
Moreover, the plasma gas supply apparatus 7 should just be the structure which can supply plasma gas to the process point Pm, and may have structures other than the structure mentioned above. In this case, other points may be the same as described above, or may be changed as appropriate.

The nozzle support 15 may be provided on the tool support 9. In this case, the second drive device 17 described above is omitted, and the other points are the same as described above.
Further, when the first driving device 13 is configured by only the table driving unit 13b of the tool side driving unit 13a and the table driving unit 13b, the nozzle support 15 may be provided on the table 11. Good. In this case, the other points are the same as described above.

1 Workpiece, 3 Fine tool (end mill), 5 Coolant supply device, 5a Coolant tank, 5b Pump, 5c Coolant tube, 5d Coolant nozzle, 7 Plasma gas supply device, 7a Power supply, 7b electrode, 7c electrode 7d plasma generating gas supply device, 7d1 gas tank, 7d2 gas pipe, 7e gas nozzle, 7e1 opening, 7f case, 7g insulating member, 7h lead wire, 7i switch, 7j valve, 8 rotary drive device (air turbine spindle), 9 tool Support body, 10 plasma gas processing apparatus, 11 units, 12 jigs, 13 first drive unit, 13a tool side drive unit, 13b platform drive unit, 15 nozzle support unit, 17 second drive unit, 19 control unit , 20 processing machine, Pm processing point, R discharge area

Claims (5)

A processing machine having a micro tool for performing micro processing on a workpiece, and a coolant supply device for supplying a coolant to a processing point of the workpiece to be micro processed by the micro tool, and plasma gas at the time of micro processing A processing apparatus using plasma gas,
The degree of unevenness on the surface of the fine tool is on the order of several microns,
By supplying a plasma gas to the processing point, the conformity between the surface of the fine tool including the processing point and the cooling liquid is improved, and the unevenness on the surface of the micro tool has a level of several microns. A coolant that reaches the surface, improves the familiarity between the surface of the workpiece including the processing point and the coolant, and provides a reaction material that is difficult to attach chips from the workpiece to the fine tool. A plasma gas utilization processing apparatus, comprising: a plasma gas supply apparatus that performs the processing. The surface of the workpiece is formed of silicon carbide,
The plasma gas supply device oxidizes silicon carbide forming the surface of the workpiece by supplying plasma gas to the surface region of the workpiece including the processing point, and forms the surface. The plasma gas processing apparatus according to claim 1, wherein the gas is changed from silicon carbide to silicon dioxide. The plasma gas supply device
A pair of electrodes a potential difference is applied,
A plasma generation gas supply device for supplying a plasma generation gas to a discharge region between the pair of electrodes,
When the plasma generation gas is supplied to the discharge region, a potential difference is applied between the pair of electrodes, whereby a discharge is generated between the pair of electrodes through the discharge region, and the plasma gas is generated from the plasma generation gas. The plasma gas processing apparatus according to claim 1 or 2, wherein the generated plasma gas supply apparatus supplies the generated plasma gas to the processing point. The said plasma gas supply apparatus has a gas nozzle which injects plasma gas to the said process point, The plasma gas utilization processing apparatus of Claim 1, 2, or 3 characterized by the above-mentioned. A plasma gas-based processing method that uses a plasma gas when performing fine processing on a workpiece with a fine tool ,
The degree of unevenness on the surface of the fine tool is on the order of several microns,
When you are working the workpiece by the micro tool, the coolant supply device, the machining point of the workpiece by the fine tools, supplies a coolant, by a plasma gas supply device, plasma in the machining point By supplying gas, the compatibility of the surface of the fine tool including the processing point and the coolant is improved, and the coolant is delivered to the unevenness on the surface of the micro tool on the order of several microns. Skein, improving the familiarity between the surface of the workpiece including the machining point and the cooling liquid, and making the chips of the workpiece difficult to adhere to the fine tool. A processing method using plasma gas.