JP2005074544A - Electrode for electrolytic inprocess dressing and grinding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode for electrolytic inprocess dressing and grinding, facilitating attachment/detachment and clearance adjustment, and stably performing the sticking formation of an electrolytic film on a grinding wheel surface by sufficient current application with sufficient filling and refilling of an electrolyte between electrodes. <P>SOLUTION: This electrode 10 for electrolytic inprocess dressing and grinding is placed to face a grinding action surface 1a of a conductive grinding wheel 1 with a clearance to grind a workpiece while dressing the grinding wheel by electrolysis by applying voltage while allowing a conductive fluid 4 to flow between them. A facing surface 10a of the electrode 10 facing the grinding action surface has a curved surface (e.g., a convex cylindrical surface) not parallel with the grinding action surface, and the clearance G gradually increases after gradually decreasing in the travel direction of the grinding wheel surface to form a micro clearance between them. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrode for electrolytic in-process dressing grinding that is easy to attach, remove, and adjust the gap.

Patent Document 1 discloses an electrolytic dressing means called an electrolytic in-process dressing grinding method (hereinafter referred to as “ELID grinding method”) by the applicant of the present application.
This ELID grinding method applies a voltage between a grindstone having a contact surface with a workpiece, an electrode facing the contact surface, a nozzle for flowing a conductive liquid between the grindstone and the electrode, and the grindstone and the electrode. A device comprising a power source and a power feeder is used to apply a voltage between the grindstone and the electrode while flowing a conductive liquid between the grindstone and the electrode, thereby dressing the grindstone by electrolysis.

The dressing mechanism by this ELID grinding method is shown in FIG. At the start of sharpening the grinding wheel (A), a relatively large current (5 to 10 A) flows with little electrical resistance between the grinding wheel and the electrode. Thereby, the metal part (bond) on the surface of the grindstone is dissolved by the electrolytic effect, and non-conductive diamond abrasive grains protrude. Further, when energization is continued, an insulating film mainly composed of iron oxide (Fe ₂ O ₃ ) is formed on the surface of the grindstone, and the electric resistance of the grindstone increases. As a result, the current is decreased, the dissolution of the bond is reduced, and the protrusion of the abrasive grains (sharpening of the grindstone) is substantially finished (B). When grinding is started in this state (C), the diamond abrasive grains are worn as the workpiece is ground while the coating releases the grinding waste. When grinding continues (D), the insulating coating on the surface of the wheel is removed by abrasion, the electric resistance of the wheel decreases, the current between the wheel and the electrode increases, the dissolution of the bond increases, and the protrusion of the abrasive grains (the wheel) Will be resumed. Therefore, during grinding by ELID grinding method, as shown in (B) to (D), excessive elution of bonds is suppressed by forming and removing the coating, and the protrusion of the abrasive grains (sharpening of the grinding stone) is automatically adjusted. The The cycle shown in (B) to (D) is hereinafter referred to as “ELID cycle”.

  In the above-mentioned ELID grinding method, even if the abrasive grains are made fine, clogging of the grinding stone does not occur due to the grinding of the grinding stone by the ELID cycle. Therefore, if the abrasive grains are made fine, an extremely excellent machining surface such as a mirror surface can be obtained by grinding. Can do. Therefore, the ELID grinding method has a feature that the sharpness of the grindstone can be maintained from high efficiency grinding to mirror grinding.

  Patent Documents 2 and 3 have been proposed as electrodes for ELID grinding described above.

As shown in FIG. 7, the “dynamic pressure generating electrode” of Patent Document 2 is opposed to the processing surface 1a of the conductive grindstone 1 with a gap, and a voltage is applied while flowing a conductive liquid between them. Electrode dressing grinding electrode 50 for grinding a workpiece while dressing by electrolysis,
The electrode 50 is provided at a distance from each other in the running direction of the grindstone surface, and has a plurality of narrowest portions 51 having a certain gap from the processing surface 1a of the grindstone, and the narrowest portion provided between the narrowest portions. And a plurality of recesses 52 having wide gaps.

As shown in FIG. 8, the “removable electrode” of Patent Document 3 is opposed to the processing surface of the conductive grindstone 1 with a gap, and a voltage is applied while flowing a conductive liquid between them, so that the grindstone is electrolyzed. An electrode 60 for electrolytic dressing grinding for grinding a workpiece while dressing,
An electrode support member 62 having a facing surface 62a spaced apart from the processing surface 1a of the grindstone, a conductive foil 64 detachably attached along the facing surface of the electrode support member, and the conductive foil It consists of a conductive terminal 66 that contacts and applies a voltage.

Japanese Patent No. 1947329 Japanese Patent No. 3214694, “Dynamic pressure generating electrode” Japanese Patent Application Laid-Open No. 2001-252869, “Removable Electrode”

Conventionally, the shape of an electrode for ELID grinding (hereinafter referred to as “static electrode”) is a shape that follows the shape of a grindstone working surface, which is a moving electrode, and has a shape that should have a constant gap in opposing surface areas. That is, as shown in FIG. 4, if the grindstone working surface 1a is a convex cylindrical surface, the shape of the opposing surface 2a of the static electrode 2 is a concave cylindrical surface. If the grindstone working surface 1a is flat as shown in FIG. The opposing surface 2a of the static electrode 2 was flat. Reference numerals 21 and 22 are electrolyte solution inlets.
The reason for this is that a liquid that electrolyzes a grinding stone that also serves as a grinding fluid (hereinafter referred to as “electrolytic solution”) has low conductivity, and a sufficient gap cannot be obtained when a large gap is left in a small opposing area. This is because the grinding wheel electrolysis suitable for the above grinding conditions (in the case of a cast iron bonded grinding wheel, the surface of the working surface is brittle and an insulating iron oxide skin is adhered and formed) cannot be obtained.
Therefore, in order to obtain quick iron oxide film adhesion / formation on the grindstone surface by sufficient energization, the gap between the electrodes is reduced (for example, 0.3 mm or less) and the opposing area is increased (for example, the area of the grindstone working surface) 1/5 to 1/3).

Therefore, in the case of a large flat grindstone 1 as shown in FIG. 4 (the grinding surface is a convex cylindrical surface), the static electrode 2 is attached and set so that the gap G is constant with respect to the grindstone surface 1a. In addition, a precise electrode position / posture adjustment mechanism is required, and in order to uniformly fill and renew the electrolyte in a large and long gap, a single inlet is not enough and two or three inlets are provided. There was a need.
Further, if the electrode gap G is further narrowed over the entire facing area to increase the energization effect, the liquid layer in the gap due to the generation of dynamic pressure by the electrolyte or the generation of oxygen or hydrogen gas by the electrolysis reaction of the liquid It was necessary to pay attention to the intermittent operation.

On the other hand, in the case of the flat working surface 1a of the cup-shaped grindstone 1 as shown in FIG. 5, the electrolytic solution is taken out in the radial direction by centrifugal force at the same time as the electrolytic solution is taken out in the rotating direction of the grindstone. In order to satisfy the requirement, it has been necessary to devise such as injecting the electrolytic solution from the entire inner circumference of the cup grindstone 1 and restricting the swinging out of the grindstone to the outside.
For this reason, the structure around the electrode is complicated, and the stability of ELID grinding is not always sufficient. In particular, when using a cup grinder with a tool grinder, it is necessary to change the mounting position of the electrode according to the site of use of the grindstone, and there is a practical demand for easy mounting, removal, and clearance adjustment in a short time. It was.

  The present invention has been made to solve such problems. That is, the object of the present invention is easy to install, remove, and adjust the gap, and the electrolyte solution between the electrodes is sufficiently charged and renewed, and the adhesion and formation of the electrolytic film on the surface of the grindstone by stable energization is stable. It is an object of the present invention to provide an electrode for electrolytic in-process / dressing grinding.

According to the present invention, an electrolysis in-process that faces a grinding action surface of a conductive grindstone with a gap, applies a voltage while flowing a conductive liquid therebetween, and grinds the workpiece while dressing the grindstone by electrolysis. An electrode for dressing grinding,
The electrode facing the grinding surface has a curved surface that is not parallel to the grinding surface, and the gap gradually increases in the running direction of the grinding wheel surface to form a minimal gap therebetween. An electrode for in-process dressing grinding is provided.

According to a preferred embodiment of the present invention, the grinding surface of the grindstone is a flat surface, and the opposing surface of the electrode is a cylindrical surface convex toward the grinding surface.
According to another preferred embodiment of the present invention, the grinding surface of the grindstone is a cylindrical surface, and the opposing surface of the electrode is a flat surface or a cylindrical surface convex to the grinding surface side. The electrode for electrolytic in-process dressing grinding according to claim 1.
Moreover, it is preferable to provide elastic support means for elastically supporting the electrode and increasing / decreasing the gap by the dynamic pressure of the conductive liquid flowing through the gap.

According to the configuration of the present invention, the facing surface of the electrode facing the grinding surface of the conductive grindstone has a curved surface that is not parallel to the grinding surface, and the gap between the grindstone and the electrode is the running direction of the grinding wheel surface (grinding direction). Since it gradually increases after being gradually reduced and a minimal gap is formed therebetween, the conductive liquid (electrolyte) adhering to the grindstone by running of the grinding wheel surface can be entrained to the position of the minimal gap.
In addition, when the minimum gap is as large as 0.1 mm to 0.3 mm, once the conductive liquid layer flowing in the running direction of the grinding wheel surface is formed in the gap between the grinding stone and the electrode, the position of the minimum gap is determined by Bernoulli's theorem. The pressure is minimized, and the conductive liquid can be stably held in that portion.
Therefore, for example, due to the effect of the shape of the electrostatic electrode surface with the electrostatic electrode surface as a convex cylindrical surface, sufficient electrolyte solution necessary for quick and stable ELID grinding is filled between the electrodes by the movement of the grindstone surface as a moving electrode. It can be updated.

  In addition, according to the configuration of the present invention, since electrolysis is performed only in the vicinity of the minimal gap between the grindstone and the electrode, the opposing length of the electrode can be shortened, and the electrode can be easily attached and adjusted. Therefore, if it is applied to a grinding operation in which the grinding wheel must be changed frequently or the usage position of the grinding wheel must be changed frequently like a tool grinder, the replacement time can be shortened and the stability of ELID can be improved.

  Moreover, if the cylindrical static electrode is appropriately elastically supported in close proximity (for example, 0.01 mm or less) using an elastic support means, the gap is caused by the dynamic pressure of the electrolytic solution according to the grinding wheel rotation speed. As the flow rate and current flow change, the electrolysis increases at low grinding wheel peripheral speeds where the grinding wheel cutting load is large, and the electrolysis is reduced at high grinding wheel speeds where the grinding wheel cutting load is small. Can be expected.

  Hereinafter, preferred embodiments of the present invention will be described. In addition, the same code | symbol is attached | subjected and used for the common part in each figure.

FIG. 1 is a diagram showing a first embodiment of an ELID grinding electrode according to the present invention, in which (A) is a front view and (B) is a cross-sectional view.
As shown in FIG. 1, the electrode 10 for electrolytic in-process dressing grinding of the present invention has a curved surface in which the facing surface 10a of the electrode facing the grinding surface 1a of the conductive grindstone 1 is not parallel to the grinding surface, The gap G gradually increases in the running direction of the grindstone surface of the grindstone 1 and gradually increases to form a minimal gap therebetween.
In this example, the conductive grindstone 1 is a cup-shaped grindstone, and its grinding surface 1a is a ring-shaped flat surface. That is, the moving electrode surface 1a is a ring-shaped plane that goes around. The electrode for electrolytic in-process dressing grinding of the present invention, that is, the static electrode 10 is a carbon cylinder, and the generatrix of the cylinder is installed parallel to the plane 1 a of the moving electrode 1. Moreover, in this figure, 21 is an electrolyte solution injection port, A is an arrow which shows the running direction of a grindstone surface, G is a clearance gap between electrodes.
Note that the gap G between the electrodes is held, for example, in a gap of 0.1 to 0.3 mm, and a positive (+) voltage is applied to the grindstone 1 and a negative (-) voltage is applied to the electrodes while the electrolytic solution 4 (conductive liquid) is flowing therebetween. Is applied to grind a workpiece (not shown) while dressing the grindstone 1 by electrolysis.

Since it has such a structure, attaching the static electrode 10 close to the grindstone 1 is only necessary to adjust the gap and parallelism between the cylindrical bus bar and the plane. For example, the grindstone 1 and the static electrode 10 What is necessary is just to fix in the state pressed with the spacer in between. Various mechanisms can be conceived as an additional mechanism for this purpose, and the parallelism between the gap between the electrodes and the bus can be adjusted independently if the mechanism can adjust and set the angle around two orthogonal axes. For this reason, the nearest part (cylindrical bus bar) of the electrode 10 can be easily made to approach 0.1 mm or less to the grindstone surface 1a.
In addition, the electrolytic solution 4 is brought between the electrodes by the traveling of the grindstone 1 (if the minimal gap is as small as about 0.01 mm, dynamic pressure is generated due to the viscosity of the liquid, and the pressure of the liquid in the vicinity of the thinnest liquid layer is normal. It becomes a flow rate and a flow rate corresponding to the speed of the grindstone 1 (which becomes higher than the pressure), and is filled and renewed between the electrodes.

The static electrode 10 is preferably formed so as to be freely rotatable around its axis. With this configuration, the static electrode 10 can freely rotate with the flow of the electrolytic solution, and the entire outer periphery of the static electrode 10 can be effectively used.
Moreover, it is preferable to provide the elastic support means 6 which elastically supports the static electrode 10 and increases or decreases the gap by the dynamic pressure of the conductive liquid flowing through the gap.

FIG. 2 is a diagram showing a second embodiment of an ELID grinding electrode according to the present invention. In this example, the grinding surface of the grindstone is a cylindrical surface, and the electrode is a partial cylindrical surface.
When the grindstone 1 is a flat shape whose grinding surface 1a is a convex cylindrical surface, the shape of the static electrode 10 is a convex cylindrical surface having a small diameter, and the opposing surface length is about 1% of the circumferential length of the grindstone. It can be difficult to get. At this time, the electrode surface shape of the static electrode 10 is preferably a convex cylindrical surface having a large radius.
The opposing surface of the electrode 10 may be a convex cylindrical surface having an infinite radius, that is, a flat surface. Further, in this case, it is preferable that the entrance shape of the electrode gap is made a trumpet shape so that the electrolyte is sufficiently brought in between the electrodes.

  FIG. 3 is a diagram showing a third embodiment of an ELID grinding electrode according to the present invention. In this example, the grinding surface of the grindstone is a cylindrical surface, and the electrode is a plurality of cylinders. In this figure, 10 is a static electrode, 21 and 31 are electrolyte inlets, A is an arrow indicating the running direction of the grindstone surface, and G2 and G3 are gaps between the electrodes. As shown in this figure, a plurality of cylindrically shaped static electrodes can be opposed to each other.

  In the case of the above-described configuration, the area of the thin liquid layer that generates the current path is smaller than that of the conventional uniform gap / large counter area electrode, so an experiment was conducted to determine whether the energization amount (film formation) was sufficient. went.

  The test conditions are: a # 3000 cast iron bond diamond grinding wheel with a cup shape (φ150 × φ130), a static electrode is a carbon cylinder (φ20 × L20), a grinding fluid is CEM, a power source is ELID power source ED-910, and a workpiece is super Hard TC20 (grinding area 1.5 mm × 1.5 mm), incision was 2 to 3 μm / pass, and grindstone rotation was 2600 rpm.

As a result, the initial current when energizing a grindstone without an electrolytic film is 2 amperes, and decreases to 0.5 amperes after 2 minutes of energization without grinding. This situation was equivalent to the situation with a planar static electrode with a large opposing area. In other words, an iron oxide insulating film was adhered and formed on the surface of the grindstone along with the energization.
The current value during grinding was 1 ampere. This shows that the balance between the scraping of the coating from the surface of the grindstone by the contact of the workpiece and the formation of a new coating is in the state of the coating that passes 1 ampere of current.
When the cut is stopped and the spark is entered, the current value is reduced to 0.5 amperes in about 1 minute, indicating that the insulating film becomes thicker. There is also a current that flows without causing electrolysis between the electrodes, and 0.5 ampere corresponds to this.
From the above, it was confirmed that the value of the energization current and the time required for film formation were the same as those of the conventional planar static electrode having a large opposing area.

  The above experimental facts are considered as follows. The electrochemical reaction of the electrode and the electrolyte between the electrodes is sufficiently faster than the peripheral speed of the grindstone and the flow of the electrolyte, and the reaction proceeds sufficiently quickly if the electrolyte is rapidly updated between the electrodes. On the other hand, when the liquid between the electrodes stays or is deficient, the reaction is saturated and does not proceed. In ELID grinding, it can be understood that the electrolytic reaction is not the reaction rate limiting but the diffusion rate limiting. That is, if the closest gap is made small, a large amount of current is passed, and the electrolyte solution is renewed accordingly, electrolysis can be sufficiently performed without increasing the counter electrode area.

  The opposing length of the planar static electrode with respect to the grinding wheel circumference was 13%, whereas that of the convex cylindrical static electrode having the same electrolysis performance as that of the planar electrode was 0.3 mm. However, when calculated as 0.8, it is 0.85%, which is only 1/15 of the flat electrode. This is the effect of making the shape of the moving electrode facing surface of the static electrode into a convex cylindrical surface suitable for filling and renewal of the electrolyte.

As described above, according to the present invention characterized in that the static electrode surface 10a is a convex cylindrical surface, sufficient electrolyte solution necessary for quick and stable ELID grinding is obtained due to the effect of the shape of the static electrode surface. Can be filled and renewed between the electrodes by the movement of the grindstone surface 1a which is a moving electrode, and since the opposing length of the electrodes is short, there is an effect that the electrodes can be easily attached and adjusted. If it is applied to a grinding operation in which the grinding wheel must be changed frequently or the usage position of the grinding wheel must be changed frequently like a tool grinder, the effect of shortening the replacement time and the stability of ELID is great.
In addition, if the cylindrical static electrode in close proximity (0.01 mm or less) is appropriately elastically supported, the gap changes due to the dynamic pressure of the electrolyte depending on the rotational speed of the grindstone, and both the amount of liquid passing through and the value of the energization current Therefore, the electrolysis increases at a low grinding wheel peripheral speed where the grinding wheel cutting load becomes large, and an adaptation effect can be expected in which the electrolysis becomes smaller at a high grinding wheel circumferential speed where the grinding wheel cutting load becomes small.

  In addition, this invention is not limited to embodiment mentioned above, Of course, it can change variously in the range which does not deviate from the summary of this invention.

It is 1st Embodiment figure of the electrode for ELID grinding by this invention. It is 2nd Embodiment figure of the electrode for ELID grinding by this invention. It is 3rd Embodiment figure of the electrode for ELID grinding by this invention. It is a figure which shows the example of the electrode for conventional ELID grinding. It is a figure which shows another example of the conventional electrode for ELID grinding. It is explanatory drawing which shows the ELID cycle in an ELID grinding method. 10 is a schematic diagram of a “dynamic pressure generating electrode” in Patent Document 2. FIG. 6 is a schematic diagram of “Removable Electrode” in Patent Document 3. FIG.

Explanation of symbols

1 conductive grinding wheel (moving electrode), 1a grinding working surface (moving electrode surface),
2 electrode (static electrode), 2a facing surface,
4 electrolyte (conductive liquid), 6 elastic support means,
10 Electrolytic in-process dressing grinding electrode (static electrode),
10a facing surface,
21, 22, 31 Electrolyte inlet

Claims (4)

This is an electrode for electrolytic in-process dressing grinding that faces the grinding surface of the conductive grindstone with a gap, applies a voltage while flowing a conductive liquid between them, and grinds the workpiece while dressing the grindstone electrolytically. And
The electrode facing the grinding surface has a curved surface that is not parallel to the grinding surface, and the gap gradually increases in the running direction of the grinding wheel surface to form a minimal gap therebetween. In-process dressing grinding electrode. 2. The electrode for electrolytic in-process dressing grinding according to claim 1, wherein the grinding surface of the grindstone is a flat surface, and the opposing surface of the electrode is a cylindrical surface convex toward the grinding surface. 2. The electrolytic in-process dressing grinding according to claim 1, wherein the grinding surface of the grindstone is a cylindrical surface, and the opposing surface of the electrode is a flat surface or a cylindrical surface convex toward the grinding surface. Electrode. The electrode for electrolytic in-process dressing grinding according to claim 1, further comprising elastic support means for elastically supporting the electrode and increasing / decreasing the gap by a dynamic pressure of a conductive liquid flowing through the gap.

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