JP7407451B2 - Processing equipment and processing method - Google Patents

Description

The present invention relates to a processing device and a processing method for mechanically removing a workpiece made of a sintered alloy made of carbide hardened with a metal binder using electrolytic action.

As a processing device for grinding cemented carbide, a composite processing device that combines electrolytic processing and grinding has been proposed (for example, see Non-Patent Document 1, Non-Patent Document 2, and Non-Patent Document 3). . This type of processing is sometimes referred to as electrolytic grinding, and was developed primarily in the United States from the 1960s to the 1970s, and is said to be a technology that attracted worldwide attention for a period of time. According to such a conventional processing device, grinding can be efficiently performed by using both the electrolytic action and the grinding action.

Author: Ren Nishimoto, article "About electrolytic grinding", "Metal Surface Technology" magazine, Volume 14, No. 1 (P. 12-20), Publisher: Surface Technology Association, 1963. Authors: Chisuke Furuno, Toshio Uchihira, Toru Usuku, Article "Research on electrolytic grinding of cemented carbide", "Metal Surface Technology" magazine, Volume 17, No. 2 (P. 46-52), Publisher: General Incorporated Association Published by Surface Technology Association, 1966 Authors: Yuji Tamura, Yuzuru Kubota, Article "About the combined effect in electrolytic grinding of cemented carbide", "Research Bulletin of the Faculty of Engineering, Ibaraki University", Vol. 20 (P. 81-86), published in 1972.

However, in the above-mentioned conventional technology, although it is possible to perform surface finishing by grinding using electrolytic action, it is not possible to obtain a workpiece of a desired shape by mechanical removal using electrolytic action. Therefore, the present applicant has developed a workpiece made of a sintered alloy made of carbide hardened with a metal binder, which is a particularly difficult-to-process material, by mechanically removing it using electrolytic action, thereby producing an efficient, high-precision, and high-performance workpiece. We have developed a processing device that can produce high-quality workpieces.

The present invention has been made in view of the above circumstances, and provides a processing device and a processing method that can efficiently process a workpiece made of a sintered alloy made of carbide hardened with a metal binder with high precision and high quality. Our goal is to provide the following.

The invention according to claim 1 provides a fixing means for fixing a workpiece made of a sintered alloy made of carbide hardened with a metal binder in a predetermined position, a rotary tool capable of mechanically removing the workpiece, and a rotary tool that rotates the rotary tool as a shaft. a rotating means for rotating the rotary tool around the workpiece; a moving means capable of moving the rotary tool relative to the workpiece; and applying a voltage between the rotary tool and the workpiece, A power supply device capable of passing an electric current between the rotary tool and the workpiece; and a metal binder removal function that uses the power supply device to remove the metal binder from a workpiece made of a sintered alloy in which the carbide is hardened with a metal binder. A processing device for performing mechanical removal processing into a desired shape with the rotary tool by applying a voltage with the power supply device and utilizing electrolytic action, the rotary tool applying voltage with the power supply device. a main body part that can flow an electric current between the workpiece through the electrolytic solution according to a voltage applied to the workpiece; and a processing part that is capable of mechanically removing the workpiece. It is characterized by having the following.

The invention according to claim 2 is the processing apparatus according to claim 1, in which the electrolyte is made of metal ions of the same material as the metal binder contained in the workpiece, or has a greater ionization tendency than the metal binder. It is characterized by the addition of metal ions.

The invention according to claim 3 is the processing apparatus according to claim 2, wherein the power supply device is capable of reversing the polarity of the voltage applied between the rotary tool and the workpiece, and It is characterized in that the added material can be deposited on the surface of the workpiece.

The invention according to claim 4 is the processing apparatus according to any one of claims 1 to 3, wherein the rotary tool is configured to move diamond or cubic boron nitride (CBN) grains as the processing portion to the main body portion. It is characterized in that it consists of an electrodeposition tool fixed to.

The invention according to claim 5 is the processing apparatus according to any one of claims 1 to 3, wherein the rotary tool is a diamond sintered body or a cubic boron nitride sintered (CBN) body as the processing section. The tool is characterized in that it consists of a tool fixed to the main body.

The invention as claimed in claim 6 is directed to a workpiece made of a sintered alloy made of carbide hardened with a metal binder while rotating a rotary tool having a main body made of a conductive material and a processing part made of an insulating material around an axis. The rotary tool is moved relative to the workpiece, an electrolyte is supplied to the gap between the rotary tool and the workpiece, and a voltage is applied between the rotary tool and the workpiece through the electrolyte to flow a current, thereby causing an electrolytic action. The method is characterized in that the metal binder of the workpiece is eluted into the electrolytic solution using the same method, and at the same time, the processing portion is brought into contact with the workpiece to mechanically remove it into a desired shape .

The invention according to claim 7 is the processing method according to claim 6, in which the electrolytic solution is made of metal ions of the same material as the metal binder contained in the workpiece, or has a greater ionization tendency than the metal binder. It is characterized by the addition of metal ions.

The invention according to claim 8 is the processing method according to claim 7, in which the polarity of the voltage applied between the rotary tool and the workpiece is reversed, and the material added to the electrolyte is transferred to the workpiece. It is characterized by being deposited on the surface of.

The invention according to claim 9 is the processing method according to any one of claims 6 to 8, in which the rotary tool moves diamond or cubic boron nitride (CBN) grains as the processing part to the main body part. It is characterized in that it consists of an electrodeposition tool fixed to.

The invention according to claim 10 is the processing method according to any one of claims 6 to 8, wherein the rotary tool is a diamond sintered body or a cubic boron nitride sintered (CBN) body as the processing part. The tool is characterized in that it consists of a tool fixed to the main body.

The invention according to claim 11 is the processing method according to any one of claims 6 to 10, in which in the rough machining, electrolytic action is used to perform mechanical removal by the rotary tool, and the finishing The processing is characterized in that mechanical removal processing is performed using the rotary tool without using electrolytic action.

According to the inventions of claims 1 and 6, since mechanical removal processing can be performed using electrolytic action, a workpiece made of a sintered alloy made of carbide hardened with a metal binder can be efficiently processed with high precision and high quality. It can be processed into

According to the invention of claims 2 and 7, the electrolytic solution contains metal ions of the same material as the material of the metal binder contained in the workpiece, or metal ions of a metal having a greater ionization tendency than the metal binder. Therefore, it is possible to suppress the elution of the metal binder in areas other than those processed by the rotary tool, and it is possible to prevent the strength of the entire workpiece from decreasing.

According to the invention of claims 3 and 8, the polarity of the voltage applied between the rotary tool and the workpiece is reversed to deposit the material added to the electrolyte on the surface of the workpiece, so that the workpiece can be easily processed. It is possible to more reliably prevent a decrease in the strength of the entire object.

According to the inventions of claims 4 and 9, the rotary tool is composed of an electroplated tool in which diamond or cubic boron nitride (CBN) grains are fixed to the main body as a machining part. Mechanical removal processing can be performed using electrolytic action.

According to the inventions of claims 5 and 10, the rotary tool is a tool in which a diamond sintered body or a cubic boron nitride sintered (CBN) body is fixed to the main body as a machining part, so it is a versatile and inexpensive tool. Mechanical removal processing can be performed using a rotating tool using electrolytic action.

According to the invention of claim 11, in rough machining, mechanical removal is performed using a rotating tool using electrolytic action, and in finishing machining, mechanical removal is performed using a rotating tool without using electrolytic action. Therefore, the machining time during finishing machining can be shortened.

An overall schematic diagram showing a processing device according to a first embodiment of the present invention Schematic diagram showing a rotary tool applied to the processing equipment Schematic diagram showing other rotary tools applied to the same processing equipment Schematic diagram showing other rotary tools applied to the same processing equipment An overall schematic diagram showing a processing device according to a second embodiment of the present invention Schematic diagram showing the addition means applied to the processing equipment Timing chart explaining voltage application timing by the power supply device in the processing equipment

Embodiments of the present invention will be specifically described below with reference to the drawings.
The processing device according to the first embodiment is for mechanically removing a workpiece made of a sintered alloy made of carbide hardened with a metal binder using electrolytic action, as shown in FIG. , a fixing means 1 for fixing the workpiece W in a predetermined position, a rotary tool K for mechanically removing the workpiece W, a rotating means M1 for rotating the rotary tool K around an axis, and the workpiece W. A moving means M2 capable of moving the rotary tool K relatively to the rotary tool K, a power supply device A constituted by an electric circuit A1 and an electric circuit A2, and an electrolyte tank 6 containing an electrolyte D. It is configured.

The workpiece W is made of a sintered alloy (cemented carbide) made of tungsten carbide (WC) hardened with cobalt (C _O 2 ) as a metal binder, and is positioned and fixed to the fixing means 1 . Note that the workpiece W to be applied may be any other sintered alloy as long as it is made of a sintered alloy made by hardening carbide with a metal binder, and titanium carbide (TiC) or tantalum carbide (TaC ), etc., or may contain chromium (Cr), nickel (Ni), etc. as a metal binder. However, for example, it may be a sintered alloy called cermet whose main component is titanium carbide (TiC) and whose metal binder is nickel (Ni).

The fixing means 1 consists of a fixing jig for positioning and fixing the workpiece W at a predetermined position, and is arranged in a processing tank E that can receive the electrolyte D. The machining tank E receives the electrolyte D supplied from the electrolyte tank 6 and spouted toward the gap between the rotary tool K and the workpiece W, and transfers the received electrolyte D to the electrolyte tank 6. It is configured so that it can be returned. A flow hole through which the electrolytic solution D can flow may be formed in the rotary tool K, and the electrolytic solution D may be spouted toward the workpiece W from there. In this embodiment, the electrolytic solution D is spouted toward the gap between the rotary tool K and the workpiece W, but a predetermined volume of the electrolytic solution D is stored in the machining tank E, and the electrolytic solution D is The workpiece W may be immersed in the liquid D and mechanically removed using electrolytic action.

The rotating means M1 includes an actuator such as a motor that rotates the rotating tool K around an axis. The rotating means M1 rotates the rotary tool K so that the processing portion (abrasive grains Kb or cutting blade K'b) can be brought into contact with the workpiece W to perform mechanical removal processing. The moving means M2 is composed of an actuator that can move the rotary tool K relative to the workpiece W, and in this embodiment, moves the rotating rotary tool K in the X-axis, Y-axis, and Z-axis directions. It is configured so that the workpiece W can be mechanically removed into a desired shape.

The rotary tool K is a tool capable of mechanically removing the workpiece W fixed by the fixing means 1, and as described above, is rotatable around the axis by the rotating means M1, and is controlled by a control means (not shown). The workpiece W is moved by a moving means M2 whose drive is controlled by the following, and is configured to mechanically remove the workpiece W into a desired shape. In this way, by mechanically removing the rotary tool K while moving in the X-axis, Y-axis, and Z-axis directions, it is possible to mechanically remove, for example, a three-dimensional mold.

The power supply device A is composed of an electric circuit including an electric circuit A1 to which a resistor 2, a switch S1, and a power source 4 are connected, and an electric circuit A2 to which a resistor 3, a switch S2, and a power source 5 are connected. The electric circuit A1 can apply a positive voltage to the workpiece W and the rotary tool K a negative voltage, and the electric circuit A2 can apply a negative voltage to the workpiece W and a positive voltage to the rotary tool K.

That is, the power supply device A is configured to apply a voltage between the rotary tool K and the workpiece W, thereby allowing current to flow between the rotary tool K and the workpiece W via the electrolyte. Therefore, it is possible to utilize electrolytic action on the workpiece W. By utilizing such electrolytic action, cobalt (C _{O 2} ) as a metal binder in the workpiece W can be eluted into the electrolytic solution, and tungsten carbide (WC) can be oxidized.

The electrolytic solution tank 6 can contain a predetermined amount of the electrolytic solution D, and has a supply channel L1 that can supply the electrolytic solution D to the fixing means 1, and a recovery channel L2 that can collect the electrolytic solution D from the fixing means 1. It is connected. Further, a pump P1 is attached to the supply flow path L1 so that the electrolyte in the electrolyte tank 6 can be fed into the fixing means 1. As the electrolytic solution D, an aqueous solution containing an electrolyte such as sodium chloride (NaCl) or sodium nitrate (NaNO ₃ ) is used.

Here, as shown in FIG. 2, the rotary tool K according to the present embodiment is made of a conductive material that is rotatable around an axis by a rotating means M1, and the electrolytic solution D is A main body part Ka that allows current to flow between the workpiece W and the workpiece W, and a processing part Kb that is made of an insulating material (high resistance material) attached to the main body part Ka and that can mechanically remove the workpiece W. Equipped with: More specifically, the rotary tool K is an electrodeposition tool in which diamond or cubic boron nitride (CBN) grains (abrasive grains) serving as the processing portion Kb are fixed to the main body portion Ka.

The rotary tool K according to the present embodiment has a function in which the processing portion Kb (abrasive grains) functions as a cutting edge for mechanical removal processing, and also prevents the main body portion Ka from electrically contacting the workpiece W. It has the following. Then, the rotated rotary tool K moves in the X-axis, Y-axis, and Z-axis directions and moves relative to the workpiece W, and the machining part Kb contacts the workpiece W and scrapes off the interfered part. Mechanical removal processing is now being performed.

In addition, instead of the rotating tool K, as shown in FIG. It may also be used as tool K'. Such a rotary tool K' has a main body K'a made of a conductive material such as cemented carbide or high-speed tool steel, and a processing part K'b as a cutting blade made of a hard and high-resistance material. is fixed to the main body part K'a by brazing (or other fixing method).

In particular, when the rotary tool K' is used for rough machining, since the machining portion K'b as a cutting edge is large, the rotary tool K' can perform mechanical removal machining more efficiently than the rotary tool K consisting of an electrodeposition tool. Furthermore, by using such a rotary tool K', it is possible to prevent electrical discharge when performing mechanical removal machining by applying a voltage to utilize electrolytic action. That is, when using the rotary tool K, mechanical removal is performed while applying a voltage using an electrodeposition tool to which hard particles are attached, so electrolytic action can be used, but usually electric discharge also occurs. I end up. If discharge occurs, it not only damages the rotary tool K, but also leaves a thermal effect on the workpiece W, and also reduces the efficiency of the electrolytic action.

On the other hand, if a rotary tool K' as shown in FIG. 3 is used, the distance between the conductive material that is the main body part K'a and the workpiece W can be maintained at a certain level or more. , it is possible to easily prevent the occurrence of discharge. For example, if the cutting edge as the processed portion K'b is made to protrude outward by about 100 μm or more beyond the conductive material that is the main body portion K'a, the generation of electric discharge can be almost prevented. Therefore, by using the rotary tool K', a higher voltage can be applied, and cobalt (Co) from the workpiece W, which is the machined part, can be eluted more efficiently. Removal processing can be performed.

In addition, instead of the rotary tool K, as shown in FIG. The rotary tool K'' may be a tool having a coating part K'c coated with an insulating material (high resistance material) except for the tip of the part K'. It is possible to limit cobalt (Co) to the tip portion of the workpiece W, suppress elution of cobalt (Co) other than the processed portion, and prevent quality deterioration of the workpiece W.

However, the lower the applied voltage, the more cobalt oxide (CoO) is generated, and when the applied voltage is higher, cobalt (Co) becomes Co ²⁺ ions and elutes, and tungsten carbide (WC) is oxidized. It is known that the reaction to form tungsten (WO ₃ ) progresses easily. If the applied voltage is 15 V or less, cobalt oxide (CoO) is likely to be generated, so the applied voltage is preferably 15 V or more. Particularly in rough machining, it is advantageous to elute a large amount of cobalt (Co), so when using a rotary tool (K', K''), the machined part (K' It is preferable to set the protrusion amount of b, K''b) to a large value and perform mechanical removal while applying a relatively high voltage (for example, 30 V or more).

Next, the operation and effect of the processing apparatus according to this embodiment will be explained.
When switch S1 is turned on (switch S2 is turned off), a negative voltage is applied to the rotary tool K and a positive voltage is applied to the workpiece W, and a current flows between the rotary tool K and the workpiece W via the electrolytic solution D. At this time, since the workpiece W is made of a sintered alloy (cemented carbide) made of tungsten carbide (WC) hardened with cobalt (C _O ) as a metal binder, the following reaction occurs.

Co- ^2e- → ^Co2-
2OH ^- -2e ^- → H ₂ O+[O]
WC+4 1/2[0] → WO ₃ +1/2CO+1/2CO ₂

That is, a reaction occurs in which cobalt (Co) emits electrons and becomes ions and is eluted into electrolytic solution D, and tungsten carbide (WC) is oxidized. Note that the ionization of cobalt (Co) is also an oxidation reaction in a broad sense. In reality, in addition to these reactions, the reaction Co + [O] → CoO also occurs. Tungsten oxide (WO ₃ ) and cobalt oxide (CoO) are insulating substances, and if the surface of the cemented carbide is covered with these substances, conduction will be lost, resulting in surface oxidation (oxidation in a broad sense including electrolytic elution). phenomenon) will stop progressing. Tungsten oxide (WO ₃ ) is a weaker substance than tungsten carbide (WC) and is easier to remove mechanically.

As described above, when a voltage is applied between the rotary tool K and the workpiece W via the electrolyte D, an electrochemical reaction occurs on the surface of the workpiece W, that is, electrolytic action (in a broad sense, elution of the metal binder, (including metal binder oxidation and carbide oxidation). As mentioned above, the most efficient processing method is to mechanically remove the weakened workpiece W by eluting the metal binder, but oxidation of the metal binder and carbide may occur. Even in this case, mechanical removal becomes easy because the carbide is weakened.

In this way, when a negative voltage is applied to the rotating tool K and a positive voltage is applied to the workpiece W, cobalt (Co) on the surface of the workpiece W is eluted, so the sintered alloy (cemented carbide) is a hard material. However, the strength is significantly reduced. Therefore, by using the electrolytic action (electrochemical action) generated in the power supply A by the machining part Kb (abrasive grains) of the rotary tool K, the surface of the workpiece W whose strength has been reduced can be improved under a low load state. Mechanical removal processing can be performed with high efficiency.

Note that Co ions, cobalt oxide (CoO), and tungsten oxide (WO ₃ ) may be generated on the surface of the cemented carbide due to electrochemical reactions, but when mechanical removal is performed using the rotary tool K, , a reaction in which cobalt (Co) is eluted as Co ions and reduces the strength of the surface is preferred. Particularly in the reaction that produces tungsten oxide (WO ₃ ), since tungsten oxide (WO ₃ ) is also a brittle substance, mechanical removal can be facilitated. As described above, in this embodiment, the strength of the machined portion of the workpiece W is reduced by using electrolytic action, and then mechanical removal processing is performed to remove the sintered alloy (cemented carbide). It can be mechanically removed very easily.

In the explanation so far, in this embodiment, a case has been described in which a direct current is caused to flow by the power sources 4 and 5, but a pulsed current may be caused to flow. If a pulsed current, especially a pulsed current of several tens of milliseconds or less, is applied, the range of electrolytic action is limited to the area immediately below the rotating tool K, which is the electrode, so that machining accuracy can be improved. Can be done. In addition, in this embodiment, a method was explained in which a unipolar voltage is applied and a current is caused to flow, but by applying a pulsed current and making it bipolar, when the workpiece W has a positive polarity, the workpiece Even if WO ₃ is generated on the surface of W, the WO ₃ can be melted when the workpiece W has negative polarity, so the operation may be performed in both polarities.

By the way, in mechanical removal machining of a workpiece W made of sintered alloy (cemented carbide), rough machining takes a long time, and finishing machining can be done in a relatively short time. Therefore, if the switch S1 is turned off during finishing to stop the electrolytic action, general-purpose mechanical removal (milling) technology can be used as is in finishing. Further, in the final finishing process, by stopping the electrolytic action, damage to the workpiece W due to elution of the metal binder can be suppressed.

Next, a processing apparatus according to a second embodiment of the present invention will be described.
Similar to the first embodiment, the processing apparatus according to the present embodiment is for mechanically removing a workpiece made of a sintered alloy made of carbide hardened with a metal binder using electrolytic action. As shown in FIG. 5, a fixing means 1 for fixing a workpiece W in a predetermined position, a rotary tool K for mechanically removing the workpiece W, and a rotating means for rotating the rotary tool K around an axis. M1, a moving means M2 capable of moving the rotary tool K relative to the workpiece W, a power supply device A constituted by an electric circuit A1 and an electric circuit A2, and an electrolyte tank containing an electrolyte D. 6 and addition means 7. Note that the same components as in the first embodiment are given the same reference numerals, and detailed description thereof will be omitted.

In the first embodiment, it is possible to efficiently process a workpiece W made of a sintered alloy made by hardening carbide, which is a difficult-to-process material, with a metal binder, but there are two technical problems. The first problem is the quality deterioration of the part of the workpiece W that comes into contact with the electrolyte D. The electrolyte D used in electrolytic machining is an aqueous solution of sodium chloride (NaCl), sodium nitrate (NaNO ₃ ), etc., so if a workpiece W such as cemented carbide comes into contact with such a conductive electrolyte D, , cobalt Co may be eluted and the strength of the workpiece W may be significantly reduced. Another problem is that when electrochemical processing is performed on the workpiece W, cobalt (Co) is preferentially eluted over tungsten carbide (WC), reducing the strength of the workpiece W. There is a possibility. Therefore, when processing the workpiece W using electrolytic action, it is essential to solve these technical problems.

As a countermeasure for the first problem, that is, the elution of cobalt (Co) from the portion of the workpiece W that comes into contact with the electrolytic solution D, it is effective to add Co ²⁺ ions to the electrolytic solution D. This is because the elution of cobalt (Co) is a reaction of Co → Co ²⁺ + 2 e ^- , and this reaction can be suppressed by increasing the Co ²⁺ concentration in electrolyte D. . When using a sodium chloride (NaCl) aqueous solution as the electrolyte D, Co ²⁺ in the electrolyte D can be increased by adding cobalt chloride (CoCl ₂ ), and a sodium nitrate (NaNO ₃ ) aqueous solution can be added. When using , Co ²⁺ can be increased by adding cobalt nitrate (Co(NO ₃ ) ₂ ).

However, through repeated experiments, it became clear that there were problems with this method. In the case of a sodium chloride (NaCl) electrolyte, by adding cobalt chloride (CoCl ₂ ), it was possible to almost suppress the elution of cobalt (Co) from the parts that come into contact with electrolyte D, but over time The effect weakens over time (eg, several days). It was found that this was because Co ²⁺ ions reacted with OH ^- ions in electrolytic solution D to form cobalt hydroxide Co(OH) ₂ and precipitate.

On the other hand, in the case of a sodium nitrate (NaNO ₃ ) electrolyte, although it had the effect of suppressing Co elution, it was not possible to completely suppress it from the beginning. The reason for this is thought to be that when cobalt nitrate (Co(NO ₃ ) ₂ ) is added to the electrolyte, the electrolyte becomes acidic. Adding cobalt nitrate (Co(NO ₃ ) ₂ ) increases the Co ²⁺ ion concentration in the electrolyte, but it also makes it more acidic, so it does not prevent the elution of cobalt (Co). It is. In the case of cobalt chloride (CoCl ₂ ), it also exhibits acidity when added to electrolytic solution D, so there is a possibility that elution of cobalt (Co) cannot be completely prevented.

Therefore, with the idea of adding a large amount of cobalt chloride (CoCl ₂ ) or cobalt nitrate (Co(NO ₃ ) ₂ ) to electrolytic solution D to prevent the elution of cobalt (Co) from workpiece W, The idea was changed to bring the Co ²⁺ ion concentration to a saturated state. That is, in the second embodiment, a metal of the same material as the metal binder (cobalt (Co) in this embodiment) contained in the workpiece W is added to the electrolyte D supplied to the fixing means 1. It is characterized by comprising an addition means 7 for adding ions (Co ²⁺ ions).

As shown in FIG. 6, the addition means 7 includes a cylindrical case 7a and a filter 7b such as a thread-wound filter. ) or coarse grains of cobalt (Co) are accommodated. Further, an inlet port 7c is formed in the housing space f, and an outlet port 7d is formed in the internal space of the filter 7b, so that the electrolytic solution D introduced into the housing space f from the inlet port 7c is cobalt. The cobalt (Co) chips or coarse grains of cobalt (Co) flow, and after passing through the filter 7b, the cobalt (Co) is led out from the outlet port 7d.

In this embodiment, circulation lines L3 and L4 are formed in the electrolyte tank 6 that accommodates the electrolyte D, and a circulation pump P2 is attached to the circulation line L3. Further, an inlet port 7c of the addition means 7 is connected to the circulation line L3, and an outlet port 7d of the addition means 7 is connected to the circulation line L4. The electrolytic solution D in the liquid tank 6 reaches the addition means 7 via a circulation line L3, and returns to the electrolytic solution tank 6 via a circulation line L4.

As a result, the electrolytic solution D in the electrolytic solution tank 6 flows through the circulation line L3 by driving the circulation pump P2, and reaches the accommodation space f via the inlet port 7c, where it collects cobalt (Co) chips or cobalt (Co). ) After the Co ²⁺ ions are added by contacting the coarse particles of the electrolyte, it passes through the filter 7b, flows through the circulation line L4 via the outlet port 7d, and returns to the electrolyte tank 6. That is, the electrolytic solution D in the electrolytic solution tank 6 is circulated between the electrolytic solution D and the addition means 7, and during the circulation process, Co ²⁺ ions are added to bring it into a saturated state.

As described above, by performing processing using the electrolytic solution D saturated with Co ²⁺ ions, elution of cobalt (Co) from areas other than the processed portion of the workpiece W can be suppressed. In addition, in order to supply the initial Co ²⁺ ions in the electrolytic solution D, a substance capable of supplying Co ²⁺ ions, such as cobalt chloride CoCl ₂ or cobalt nitrate Co(NO ₃ ) ₂ , may be added in advance. good.

On the other hand, if the electrolytic solution D is circulated in an open state, it will be stirred while being bubbled in an environment in which it is exposed to the atmosphere, and oxygen will dissolve into the electrolytic solution D, which may damage the workpiece W to be machined. That is, the dissolved oxygen causes cobalt (Co) in the workpiece W to be eluted through the reactions H ₂ O + 1/2O ₂ + 2e ^- → 2OH ^- and Co → Co ²⁺ + 2e ^- .

Therefore, while the electrolytic solution D is being circulated, it is preferable to cover the electrolytic solution D with a cover as much as possible and circulate it quietly so as not to create bubbles. Moreover, in that case, it is preferable to supply an inert gas such as nitrogen or argon between the electrolytic solution D and a cover that covers the electrolytic solution D. By circulating the electrolyte D in this way, Co ²⁺ ions are supplied into the electrolyte D, but the Co ²⁺ ions gradually change to Co ²⁺ + 2OH ^- → Co(OH) ₂ and form a precipitate. is generated.

During the circulation process, this precipitate is captured by the filter 7b, and the insufficient Co ²⁺ ions are supplied by cobalt (Co) chips or coarse cobalt (Co) particles in the accommodation space f. , the electrolytic solution D is always kept saturated with Co ²⁺ ions under those conditions. Note that "saturation" as used herein does not refer to a saturation phenomenon in the strict sense, but refers to a phenomenon in which ions are eluted from a metal that has come into contact with the electrolytic solution D in an equilibrium state. In other words, the state in which the ion concentration does not increase any further even if the electrolyte continues to touch the metal is called "saturation."

If only a positive polarity voltage is applied to the workpiece W in this state, the elution of cobalt (Co) may partially progress to a deep level, and it must be removed by mechanical removal. There may also be some residual damage. Therefore, especially in semi-machining and finishing machining, it is necessary to apply voltages of opposite polarity. That is, switch S1 is turned off, switch S2 is turned on, and the polarity of the voltage applied between the rotary tool K and the workpiece W is reversed (a negative voltage is applied to the workpiece W and a positive voltage is applied to the rotary tool K). voltage applied).

At this time, Co ²⁺ ions in the electrolyte D (material added to the electrolyte D) are deposited on the surface of the workpiece W by a reaction of Co ²⁺ + 2 e ^- → Co. Since the polarity is normally switched in a time of several tens of milliseconds or less, the microscopic phenomenon is the repeated elution and precipitation of cobalt (Co), but the macroscopic phenomenon is that the positive polarity of the workpiece W and The elution rate of cobalt (Co) can be adjusted by adjusting the ratio of negative polarity.

FIG. 7 shows schematic waveforms of the voltage and current applied between the rotary tool K and the workpiece W. As mentioned above, the period of polarity switching is about several tens of milliseconds or less. Here, the time for applying a positive voltage to the workpiece W is T1, the time for applying a negative voltage to the workpiece W is T2, and the ratio of the positive time for the workpiece W is T1/(T1+T2) as Duty. In the case of only electrolytic action, there is a duty at which the machining speed is the highest.

When electrolyte D is a sodium chloride (NaCl) aqueous solution, the machining speed reaches its peak when the duty is around 70%, and when electrolyte D is a sodium nitrate (NaNO ₃ ) aqueous solution, the machining speed reaches a peak when the duty is around 50%. speed reaches its peak. This value is for the peak processing speed when melting WC, which is a component of the workpiece W (cemented carbide). In the case of inventions, a duty higher than this value is a good condition. That is, when using a sodium chloride (NaCl) electrolyte, the duty is preferably 70% or more, and when using a sodium nitrate (NaNO ₃ ) electrolyte, the duty is preferably 50% or more. Note that even in the case of using an electrolytic solution of other components, it is preferable that the duty is 50% or more.

Further, the addition means 7 according to the present embodiment adds metal ions (i.e., Co ²⁺ ions) of the same material as the material of the metal binder contained in the workpiece W to the electrolytic solution D. However, instead of or in addition to this, metal ions of a metal having a greater ionization tendency than the metal binder contained in the workpiece W may be added. For example, when Fe ²⁺ ions are added to the electrolytic solution D as metal ions of a metal that has a greater ionization tendency than the metal binder contained in the workpiece W, the reaction of Fe → Fe ²⁺ + 2e ^- generates enough electrons. Since it is supplied into the electrolytic solution D, the reaction of Co→Co ²⁺ + 2 e ⁻ can be suppressed.

Also, in the machining part, by turning on switch S2 and turning off switch S1, when a negative voltage is applied to the workpiece W and a positive voltage to the rotary tool K, a reaction of Fe ²⁺ → Fe occurs. , iron Fe is deposited on the surface of the workpiece W, and by turning on the switch S1 while turning off the switch S2, a positive voltage is applied to the workpiece W and a negative voltage is applied to the rotary tool K, and cobalt (Co) is deposited on the surface of the workpiece W. ) is preferentially eluted, which has the effect of protecting cobalt (Co) on the surface of the workpiece W.

However, Fe ²⁺ ions easily change to Fe ³⁺ ions if left unattended, and the effect of protecting cobalt (Co) on the surface of the workpiece W is almost eliminated. The reason is that even if the workpiece W has negative polarity, the standard electrode potential Fe ²⁺ + 2 e ^- = Fe -0.440V (2H ⁺ + 2 e ^- = H ₂ 0.000V), Fe ³⁺ + e ^- = Fe ²⁺ +0.771V, the reaction progresses more easily from Fe ³⁺ → Fe ²⁺ than from Fe ²⁺ → Fe, so just by changing Fe ³⁺ → Fe ²⁺ , the workpiece This is because Fe is no longer precipitated on the surface of W.

Therefore, in order to protect the workpiece using Fe ions, it is necessary to keep the Fe ions in the Fe ²⁺ state. Therefore, in the addition means 7 shown in FIG. 6, chips of iron (a steel material whose main component is Fe) or coarse grains of iron may be accommodated in the accommodation space f. In this case, the electrolytic solution D in the electrolytic solution tank 6 flows through the circulation line L3 by driving the circulation pump P2, and reaches the accommodation space f via the inlet port 7c, where it collects iron chips or coarse particles of iron. After Fe ions are added thereto, it passes through the filter 7b, flows through the circulation line L4 through the outlet port 7d, and returns to the electrolyte tank 6. That is, the electrolytic solution D in the electrolytic solution tank 6 is circulated between the electrolytic solution D and the addition means 7, and Fe ions are added during the circulation process to bring it into a saturated state.

That is, as the electrolytic solution D flows in contact with iron chips or coarse grains of iron in the accommodation space f, Fe ²⁺ is supplied in the order of Fe → Fe ²⁺ . When Fe ²⁺ is left alone, it changes as Fe ²⁺ → Fe ³⁺ , but due to the relationship of the standard electrode potential mentioned above, the reaction of Fe → Fe ²⁺ is faster than the reaction of Fe ²⁺ → Fe ³⁺ . Since it is easy to proceed, it is possible to supply Fe ²⁺ ions and to suppress the change of Fe ²⁺ ions to Fe ³⁺ ions.

Thereby, the electrolytic solution D passing through the addition means 7 can be maintained in a colorless and transparent state. Incidentally, when a small amount of electrolyte D is taken out and left for circulation, the color changes from yellow to dark yellow to brown in a few hours, which confirms the presence of Fe ²⁺ ions in electrolyte D. . In this way, the electrolyte D is kept colorless, but the piping parts and the walls of the electrolyte tank 6 turn brown, so the phenomenon of Fe ²⁺ turning into Fe ³⁺ is occurring, albeit slightly. I know that there are. The iron ions that have become Fe ³⁺ become Fe(OH) ₃ and are captured by the filter 7b of the addition means 7.

In addition, in this embodiment as well, in addition to the rotary tool K, a rotary tool K' or a rotary tool K'' can be used as in the first embodiment. Also, as in the first embodiment, finishing machining Damage to the workpiece W due to elution of the metal binder may be suppressed by turning off the switch S1 and stopping the electrolytic action.Furthermore, instead of the power supplies 4 and 5 that flow a direct current, a pulsed It is also possible to cause a current to flow.

According to the first embodiment and the second embodiment, since the mechanical removal process can be performed using electrolytic action, the workpiece W made of a sintered alloy made of carbide hardened with a metal binder can be efficiently removed. It can be processed with high precision and high quality. Further, the electrolytic solution D applied to this embodiment has metal ions of the same material as the material of the metal binder contained in the workpiece W, or metal ions of a metal having a larger ionization tendency than the metal binder. Therefore, it is possible to suppress elution of the metal binder in areas other than the area to be machined by the rotary tool K, and it is possible to prevent a decrease in the strength of the entire workpiece.

Furthermore, the rotary tool K used is an electroplated tool with diamond or cubic boron nitride (CBN) grains fixed to the main body Ka as the machining part Kb. It can be used to perform mechanical removal processing. Furthermore, the rotary tools (K', K'') used are those in which a diamond sintered body or a cubic boron nitride sintered (CBN) body is fixed to the main body part K'a as the machining part K'b. Therefore, mechanical removal can be performed using electrolytic action using a general-purpose and inexpensive rotary tool.

Further, according to the second embodiment, the polarity of the voltage applied between the rotary tool K and the workpiece W is reversed to deposit the material added to the electrolytic solution D on the surface of the workpiece W. Therefore, a decrease in the strength of the entire workpiece W can be more reliably prevented. Furthermore, in rough machining, the rotary tool K performs mechanical removal using electrolytic action, and in finishing machining, the rotary tool K performs mechanical removal without using electrolytic action (stopping the electrolytic action). By performing removal machining, the machining time during finishing machining can be shortened.

Although the present embodiment has been described above, the present invention is not limited thereto, and the rotating tools (K, K', K'') are made of a conductive material that is rotatable around the axis by the rotating means M1, A main body (Ka, Ka') through which a current can flow between the workpiece W and the workpiece W via the electrolytic solution D by a voltage applied by the power supply A, and an insulating material attached to the main body (Ka, Ka'). Any other type of processing apparatus may be used as long as it is equipped with a processing section (Kb, Kb') capable of mechanically removing the workpiece W.

In addition, while rotating a rotary tool (K, K', K") having a main body part (Ka, Ka') made of a conductive material and a processing part (Kb, Kb') made of an insulating material around its axis, is moved relative to the workpiece W made of a sintered alloy hardened with a metal binder, and an electrolytic solution D is supplied to the gap between the rotating tool (K, K', K'') and the workpiece W. A voltage is applied between the rotary tool (K, K', K'') and the workpiece W through the electrolytic solution D to flow a current, and the metal binder of the workpiece W is transferred to the electrolytic solution W using electrolytic action. Any other form of processing method may be used as long as it is a processing method in which the processed portions (Kb, Kb') are brought into contact with the workpiece W and mechanically removed at the same time as being eluted.

The rotary tool is made of an electrically conductive material that is rotatable around an axis by a rotating means, and includes a main body that can flow an electric current between the workpiece and the workpiece via an electrolyte by a voltage applied by a power supply device; A processing device comprising a processing section made of an insulating material attached to a section and capable of mechanically removing a workpiece; and a rotating tool having a main body section made of a conductive material and a processing section made of an insulating material. While rotating the carbide, the carbide is moved relative to a workpiece made of a sintered alloy hardened with a metal binder, an electrolytic solution is supplied to the gap between the rotating tool and the workpiece, and the carbide is rotated through the electrolyte. A voltage is applied between the tool and the workpiece to flow a current, and the metal binder from the workpiece is eluted into the electrolytic solution using electrolytic action, while at the same time the processing section is brought into contact with the workpiece for mechanical removal. This processing method can also be applied to items with different external shapes or items with other functions added.

1: Fixing means 2, 3: Resistor 4, 5: Power supply 6: Electrolyte tank 7: Addition means 7a: Case 7b: Filter K: Rotating tool M1: Rotating means M2: Moving means A: Power supply device D: Electrolyte W: Workpiece S1, S2: Switch L1: Supply channel L2: Recovery channel L3, L4: Circulation line

Claims (11)

fixing means for fixing in place a workpiece made of a sintered alloy made of carbide hardened with a metal binder;
a rotary tool capable of mechanically removing the workpiece;
a rotation means for rotating the rotary tool around an axis;
a moving means capable of moving the rotary tool relative to the workpiece;
a power supply device that can apply a voltage between the rotating tool and the workpiece and flow a current between the rotating tool and the workpiece via an electrolytic solution;
a metal binder removal function that uses the power supply device to remove the metal binder from a workpiece made of a sintered alloy in which the carbide is hardened with a metal binder;
A processing device for applying a voltage with the power supply device to utilize electrolytic action to perform mechanical removal processing into a desired shape with the rotary tool,
The rotary tool is
a main body portion capable of passing a current between the electrolyte and the workpiece according to a voltage applied by the power supply device;
a processing section made of an insulating material attached to the main body and capable of mechanically removing the workpiece;
A processing device characterized by comprising: 1. The electrolytic solution is formed by adding metal ions of the same material as the material of the metal binder contained in the workpiece, or metal ions of a metal having a greater ionization tendency than the metal binder. Processing equipment described. The power supply device is capable of reversing the polarity of the voltage applied between the rotary tool and the workpiece, and is capable of depositing the material added to the electrolyte on the surface of the workpiece. 3. The processing apparatus according to claim 2. According to any one of claims 1 to 3, the rotary tool is an electrodeposition tool in which diamond or cubic boron nitride (CBN) grains are fixed to the main body as the processing part. processing equipment. Any one of claims 1 to 3, wherein the rotary tool is a tool in which a diamond sintered body or a cubic boron nitride sintered (CBN) body is fixed to the main body as the processing part. The processing equipment described in . A rotary tool having a main body made of a conductive material and a processing part made of an insulating material is rotated around its axis while moving the carbide relative to a workpiece made of a sintered alloy hardened with a metal binder, and An electrolytic solution is supplied to the gap between the rotating tool and the workpiece, a voltage is applied between the rotating tool and the workpiece through the electrolytic solution, and a current is caused to flow between the rotating tool and the workpiece. A processing method characterized by dissolving the metal binder into the electrolytic solution and at the same time bringing the processing section into contact with the workpiece to mechanically remove it into a desired shape . 6. The electrolytic solution is characterized in that metal ions of the same material as the metal binder contained in the workpiece or metal ions of a metal having a greater ionization tendency than the metal binder are added. Processing method described. The processing method according to claim 7, characterized in that the polarity of the voltage applied between the rotary tool and the workpiece is reversed, and the material added to the electrolyte is deposited on the surface of the workpiece. . According to any one of claims 6 to 8, the rotary tool is an electrodeposition tool in which diamond or cubic boron nitride (CBN) grains are fixed to the main body as the processing part. processing method. Any one of claims 6 to 8, wherein the rotary tool is a tool in which a diamond sintered body or a cubic boron nitride sintered (CBN) body is fixed to the main body as the processing part. Processing method described in. In rough machining, the rotary tool performs mechanical removal using electrolytic action, and in finishing, the rotary tool performs mechanical removal without using electrolytic action. The processing method according to any one of items 6 to 10.

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