JP3194621B2 - Method and apparatus for generating spherical surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CG processing method using an electrolytic in-process dressing method and an apparatus therefor.

[0002]

2. Description of the Related Art Documents in which the above-described in-process dressing method is applied to CG processing are already known. For example,
JP-A-3-60973 is known. The technique described in this publication will be described with reference to FIGS. FIG.
FIG. 1A is a cross-sectional view showing a main part of Example 1 shown in FIG. FIG.
FIG. 3B is a cross-sectional view showing a main part of a method for forming an electrode portion according to a third embodiment, which is shown in FIG. FIG. 11 is a cross-sectional view showing FIG. 3 (b) described in the above-mentioned publication and showing a side surface of a main part showing a generating operation subsequent to FIG. FIG. 12 shows FIG. 3 (c) described in the above-mentioned publication, and is a cross-sectional view from the side showing the generating action subsequent to FIG.

As shown in FIG. 9, a grinding surface 34 disposed at a swivel angle α with respect to an axis 33 of a work 32 loaded on a rotatable chuck 31 has the same shape as the curvature of the work. The conductive grinding tool 35 formed on the rotary shaft 36 is rotatably held at a rotation axis 36. Also, brush 3
7, a (+) electrode is applied from a power supply device 38, and a (-) electrode 39 formed into a curvature R _A- 1 having a shape approximate to the processing curvature R _A of the work 32 is ground by the conductive grinding tool 35. It is arranged between the surface 34 and the work 32. In the vicinity of the (−) electrode 39, a coolant 40 is interposed between the (−) electrode 39 and the grinding surface 34, and an electric current supplied from the power supply device 38 causes an electrolytic dress (that is, electrolytic dressing) of the grinding surface 34. A nozzle 41 is provided to perform the above operation.
In the CG processing method having the above configuration, the grinding is performed while rotating the chuck 31 and the conductive grinding tool 35 to perform electrolytic dressing of the grinding surface 34 between the (−) electrode 39 and the grinding surface 34. The surface 34 contacts the work 32 and
Grinding has been performed.

FIGS. 10, 11 and 12 show another embodiment of the above publication. As shown in the figure, a rectangular electrode blank 44 arranged opposite to the grinding surface 43 of the conductive grinding tool 42 is brought into contact with the grinding surface 43 of the rotating conductive grinding tool 42, and the conductive grinding tool 42 is cut into the electrode blank 44, and the surface of the electrode blank 44 facing the ground surface 43 is formed in the same shape as the ground surface 43 as shown in FIG. As shown in FIG. 12, when the work 45 is machined, the ground surface 43 and the (−)
The CG processing by the electrolytic in-process dressing method is performed while maintaining a small gap 46 between the electrodes.

[0005]

However, in order to accurately perform electrolytic in-process dressing by the spherical surface forming method described in the above-mentioned publication, it is necessary to make each point on the surface facing the ground surface of the (-) electrode. It is necessary to keep the distance from the ground surface constant and to make the current density at each point of the ground surface to be electrolytically dressed uniform. However, the ground surface of the conductive grinding wheel as shown in FIG. 9 is gradually ground by the grinding process and the dressing effect, so that the distance between the electrode surface of the fixed electrode and the ground surface of the wheel is increased. The radius of curvature R _A− l with respect to the radius of curvature R _A of the ground surface of the conductive grinding wheel.
It is difficult to dispose the (-) electrode formed in the above and the ground surface accurately and always at a constant distance.

Further, in order to solve the above-mentioned problems, as shown in FIGS. 10, 11 and 12, the electrode is driven in a direction in which the grinding wheel grinding surface wears out, and the electrode surface of the electrode and the grinding wheel grinding surface are driven. A technique for keeping the distance to the camera constant is described. In this case, since the curvature of the electrode surface and the curvature of the ground surface have the same radius, their centers of curvature do not coincide with each other.
(−) When the gap l is maintained after the curvature _{RA of the} electrode is formed, (−) the distance between each point facing the ground surface of the electrode and the ground surface of the conductive tool (that is, the distance at the ground surface). The distance between the ground surface and the (-) electrode in the normal direction is not constant. Therefore, in the technique of the above publication, when the distance between the ground surface and the (−) electrode in the normal direction on the grinding surface of the grinding stone is different at each of the points, the discharge action between each point and the ground surface is reduced. Differences occur and the electrolytic in-process dressing cannot be performed precisely. That is, it is impossible to perform the spherical surface creation processing with high accuracy.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has a constant distance between each point facing a grinding surface of an electrode and a grinding wheel grinding surface in the normal direction of each point. It is an object of the present invention to provide a method and an apparatus for precisely performing electrolytic in-process dressing of a surface and performing high-accuracy spherical surface creation processing.

[0008]

In order to solve the above-mentioned problems, a spherical surface generating apparatus according to the first aspect of the present invention comprises: a conductive grinding tool provided with a grinding surface formed in the same shape as the curvature of a work; A dress electrode disposed at a position facing the grinding surface of the conductive grinding tool, coolant supply means for supplying a weakly conductive coolant between the dress electrode and the conductive grinding tool, and application to the dress electrode Polarity switching means for switching the polarity between when performing the electrolytic dressing of the grinding surface of the conductive grinding tool and when performing the electrolytic processing of the electrode surface of the dress electrode is provided. According to a second aspect of the present invention, there is provided a method for generating a spherical surface, wherein a weakly electric coolant is provided between a ground surface of a conductive grinding tool for grinding a workpiece and a dress electrode provided to be opposed to the ground surface at a predetermined interval. And applying a positive electrode to the dress electrode and a negative electrode to the conductive grinding tool to electrolytically process the dress electrode. According to a third aspect of the present invention, there is provided the spherical surface forming method, wherein the weakly electric coolant is provided between a grinding surface of a conductive grinding tool for grinding a workpiece and a dress electrode provided at a predetermined distance from the grinding surface. Supplying an anode to the dress electrode, a step of electrolytically processing the dress electrode by applying a cathode to the conductive grinding tool, and applying a cathode to the dress electrode and an anode to the conductive tool, respectively. And electrolytically dressing the grinding surface of the conductive grinding tool. The method for generating a spherical surface according to the invention of claim 4 is characterized in that between a grinding surface of a conductive grinding tool for grinding a workpiece and a dress electrode provided opposite to the grinding surface at a constant interval.
Supplying a weakly conductive coolant, switching the respective polarities of the dress electrode and the conductive grinding tool to perform electrolytic dressing of the grinding surface of the conductive grinding tool or electrolytic processing of the electrode surface of the dress electrode, and performing the conductive grinding. The workpiece is processed on the ground surface of the conductive grinding tool during electrolytic dressing of the ground surface of the tool.

According to the first aspect of the present invention, the polarity to be applied to the dress electrode by the polarity switching means is determined when the electrolytic dressing of the ground surface of the conductive grinding tool is performed and when the electrolytic processing of the electrode surface of the dress electrode is performed. By performing the above switching, it is possible to perform electrolytic dressing on the ground surface of the conductive grinding tool and to perform electrolytic processing on the electrode surface of the dress electrode. According to the second aspect of the invention, the dress electrode can be electrolytically processed by applying the anode to the dress electrode and the cathode to the conductive grinding tool. According to the invention of claim 3, electrolytic processing of the dress electrode is performed by applying the anode to the dress electrode and the cathode to the conductive grinding tool, and the cathode is applied to the dress electrode and the anode is applied to the conductive grinding tool. This makes it possible to electrolytically dress the ground surface of the conductive grinding tool. According to the invention of claim 4, electrolytic dressing of the ground surface of the conductive grinding tool or electrolytic processing of the electrode surface of the dress electrode is performed by switching the respective polarities of the dress electrode and the conductive grinding tool. The workpiece can be processed on the ground surface at the same time as performing the electrolytic dressing on the ground surface.

[0010]

Embodiment 1 The concept of the present invention will be described with reference to the drawings.
FIG. 1 is a side sectional view showing the concept of a method and apparatus for generating a spherical surface according to the present invention. FIG. 2 is a cross-sectional side view showing an operation state of the method and apparatus for generating a spherical surface shown in FIG. As shown in FIG. 1, a grinding wheel 2 is integrally mounted on the edge of the tip of a cup-shaped conductive grinding tool 1, and its base end is moved in the direction indicated by an arrow in conjunction with driving means (not shown). It is configured to rotate. The grinding surface 3 of the grinding wheel 2 is formed to have the same curvature R _{A as} that of a work (not shown), and the surface facing the grinding surface 3 has a shape approximate to the curvature R _A with respect to the rotating conductive grinding tool 1. The formed dress electrode 4 is disposed with a slight gap 1 provided. Then, as shown in FIG. 2, the conductive grinding tool 1 is rotated, and the conductive grinding tool 1 is connected to the (-) pole of the power supply 5 and the dress electrode 4 is connected to the (+) pole of the power supply 5 in FIG. The connection is made by switching from the electrolytic dressing processing state, and power is supplied from the power supply device 5 with the weakly electric coolant 6 interposed therebetween. The operation of the above configuration will be described. As shown in FIG. 2, electrolytic processing is performed while rotating the conductive grinding tool 1 using the dressing electrode 4 having the grinding surface 3 as a (−) electrode and the (+) electrode as a workpiece. In electrolytic processing, the elution removal rate of a workpiece is proportional to the distance between each point on the workpiece and a (-) electrode. As a result, when processing the work, if the polarity is switched as shown in FIG. 1, each point of the surface of the dress electrode 4 facing the grinding surface 3 in FIG. The distance between the grinding surface 3 and the dress electrode 4 in the normal direction of the certain grinding surface 3 (in other words, the distance between each point and the grinding surface 3 in the normal direction of each point of the dress electrode 4) is precisely equidistant. Therefore, the grinding surface 3 is favorably electrolytically processed by the dress electrode 4. A specific example of the method and apparatus for generating a spherical surface according to the present invention will be described with reference to the drawings. The present embodiment is a method for generating a spherical surface by electrolytic in-process dressing grinding using a curve generator method. FIG. 3 is a cross-sectional side view showing a main part of Embodiment 1 of the method and apparatus for generating spherical surface according to the present invention. FIG. 4 is a side sectional view showing an operation state of grinding a workpiece by the apparatus of FIG. In the drawings, the same members, the same shapes, and the same configurations as those in FIGS.

As shown in FIG. 4, a ground surface having the same curvature _RA as the ground surface of the convex workpiece 7 loaded on the chuck 16 connected to the inclined rotating shaft is provided. The cup-shaped conductive grinding tool 1 having a rotating member 3 is configured to be rotated in a direction indicated by an arrow by a driving unit (not shown). As shown in FIG. 3, an L-shaped dress electrode 4, which faces the grinding surface 3 and faces the grinding surface 3 made of Cu and has an approximate shape to the curvature _RA of the grinding surface 3, is driven by a drive unit. Reference numeral 10 denotes a holding structure that is movable in the direction indicated by the arrow. In addition, conductive grinding tool 1
An electrode brush 11 is slidably abutted on the outer peripheral surface of the electrode, and the dress electrode 4 and the electrode brush 11 are electrically connected to a power supply device 5 for supplying a DC pulse current. Further, the polarity of the dress electrode 4 and the electrode brush 11 can be changed by the switching SW 13 as the polarity switching means of the (+) pole and the (−) pole of the output terminal of the power supply device 5. Reference numeral 14 shown near the position below the grindstone 2 and the dress electrode 4 is a coolant nozzle for supplying the weak electric coolant 6 from coolant supply means (not shown) between the grinding surface 3 and the dress electrode 4.

Next, the operation of the present embodiment having the above configuration will be described. First, in the state of FIG. 3, the conductive grinding tool 1 is rotated in the direction of the arrow without applying a charge, and the weak electric coolant 6 is supplied toward the contact surface between the grinding surface 3 and the dress electrode 4. Subsequently, by driving the drive unit 10 in the direction of the arrow, the dress electrode 4 and the grinding surface 3 of the conductive grinding tool 1 are brought into contact with each other, and the dress electrode 4 is ground by the conductive grinding tool 1 so as to be conductive. The shape of the grinding surface 3 of the abrasive grinding tool 1 is transferred to the dress electrode 4. In this case, no charge is applied to the conductive grinding tool 1 and the dress electrode as described above. The transfer of the grinding surface 3 of the conductive grinding tool 1 to the surface of the dress electrode 4 is completed as described above, and the dress electrode 4 is moved in the direction indicated by the arrow (original position) by the driving of the driving means 10, and the dress is moved. A predetermined gap 1 is provided between the electrode 4 and the grinding surface 3.

In the above, the new electrode surface formed on the dress electrode 4 has the same curvature as the grinding surface 3 of the grinding wheel 2, and a gap between the dress electrode 4 and the conductive grinding tool 1. When l is configured, the center of curvature of the electrode surface of the dress electrode 4 and the center of curvature of the grinding surface 3 of the grinding wheel 2 are separated from each other, and each point of the electrode and each point of the grinding surface facing each other in the normal direction at the point. Distance is no longer constant. In order to keep the distance between each point of the electrode and each point of the grinding surface 3 facing in the normal direction constant, the center of curvature of the electrode surface of the dress electrode 4 and the center of curvature of the grinding wheel 2 are matched. It will be constant.

Next, as shown in FIG. 3, the (−) pole of the power supply 5 is connected to the electrode brush 11 disposed on the outer peripheral surface of the conductive grinding tool 1, and the (+) pole is connected to the dress electrode 4. Then, a DC pulse current is supplied from the power supply device 5. In this case, the dress electrode 4 is subjected to electrolytic processing using the ground surface 3 having the curvature _RA as the (-) electrode, and the surface of the dress electrode 4 facing the ground surface 3 is ground with each point of the facing surface. An R shape having a curvature is formed such that the distance between the grinding wheel 2 and the grinding surface 3 (that is, the distance in the normal direction) is constant.

In electrolytic machining, the elution and removal speed of the workpiece increases as the distance between the workpiece and the electrode increases, and conversely, as the distance between the workpiece and the electrode increases. The rate of elution and removal of the substance becomes slow. Therefore, when the dress electrode 4 is electrolytically processed, the distance between each point of the dress electrode 4 and each point of the ground surface 3 facing in the normal direction becomes constant. Here, the center of curvature of the electrode surface (R surface) formed on the dress electrode 4 coincides with the center of curvature of the grinding wheel 2.

After the electrolytic processing of the dress electrode 4 is completed, the polarity is switched as shown in FIG. 4, and the (+) pole of the power supply 5 is connected to the electrode brush 11, and the (-) pole is connected to the dress electrode 4, so that the current is applied. The grinding surface 3 is precisely and uniformly subjected to electrolytic dressing. After the completion of the electrolytic dressing, the workpiece 7 loaded in the rotatable chuck 16 is ground to perform a highly accurate spherical generation processing. If the above-mentioned spherical surface generation processing is continued, the distance between the electrode surface and the grinding surface 3 increases, and it becomes impossible to perform electrolytic dressing under the same conditions as in the initial stage of the grinding processing. Therefore,
The driving device drives the electrode surface in the direction of the arrow shown in the drawing so as to keep the distance between the electrode surface and the grinding surface 3 separated by the consumption of the grinding surface at the same interval as that in the initial processing. Electrolytic dressing can be performed under the same conditions.

[0017]

Second Embodiment A second embodiment of the method and apparatus for generating a spherical surface according to the present invention will be described with reference to FIGS. FIG. 5 is a side sectional view showing a main part according to a second embodiment of the method and the apparatus for generating a spherical surface according to the present invention. FIG. 6 is a cross-sectional view of a main part configuration of the grindstone and the dress electrode in a state of operation based on FIG. FIG. 7 is a cross-sectional view of a main part configuration of the grindstone and the dress electrode in a state of operation following FIG. FIG. 8 is an enlarged cross-sectional side view showing a main part configuration of the grindstone and the dress electrode in an operation state following FIG. In the drawings, the same members, the same shapes, and the same configurations as those in the conceptual diagrams of FIGS. 1 and 2 and the first embodiment of FIGS. 3 and 4 are denoted by the same reference numerals and description thereof is omitted.

The difference between the present embodiment and the first embodiment is that the dress electrode 4 is formed of a general electrode material in the first embodiment, whereas the dress electrode 4 is formed in the present embodiment. 17 is made of a conductive grinding tool material. The rest of the construction is the same as in the first embodiment. Therefore, the dressing electrode is formed by the same method as in the first embodiment, and the spherical surface is formed by electrolytic in-process dressing grinding.

By the way, when the above-mentioned spherical surface forming processing is continuously performed on a large number of works 7, as shown in FIG.
The grinding surface 3 of the conductive grinding tool 1 wears unevenly. For this reason, there arises a problem that precise spherical surface generation processing cannot be performed. As shown in FIG. 7, in this embodiment, the ground surface 3
The drive unit 10 makes the dress electrode 17 abut against the ground surface 3 and cuts into a desired size when uneven wear occurs. Since the dress electrode 17 is subjected to electrolytic processing and dressing in the above-described process of forming the dress electrode 17, the shape of the dress electrode 17 is transferred to the ground surface 3, and uneven wear portions of the ground surface 3 are removed. Is done. Next, as shown in FIG. 8, a slight gap 1 is provided between the dress electrode 17 and the ground surface 3 by the drive unit 10, and the dress electrode 17 is formed.
The (−) pole of the power supply device 5 is electrically connected to the (+) pole of the power supply brush 11, and a DC pulse current is supplied. Creation processing is performed.

[0020]

According to the present invention, the distance between the dress electrode and the grinding surface of the grinding wheel of the conductive grinding tool in the normal direction of the grinding surface is always kept precisely and constant by a simple apparatus and method. Therefore, the electrolytic dressing of the ground surface of the work can be performed precisely, so that there is an effect that highly accurate spherical surface generation processing can be continuously performed.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a conceptual configuration of a method and apparatus for generating a spherical surface according to the present invention.

FIG. 2 is a side sectional view showing an operation state according to the configuration of FIG. 1;

FIG. 3 is a side sectional view showing a main part of the first embodiment of the method and apparatus for generating a spherical surface according to the present invention.

FIG. 4 is a side sectional view showing an operation state of grinding a workpiece by the apparatus of FIG. 3;

FIG. 5 is a side sectional view showing a main part according to a second embodiment of the spherical surface forming method and apparatus of the present invention.

FIG. 6 is a cross-sectional side view showing a main part configuration of a grindstone and a dress electrode in an operation state based on FIG. 5 in an enlarged manner.

FIG. 7 is a cross-sectional view of a main part configuration of the grindstone and the dress electrode in a state of operation following FIG.

FIG. 8 is an enlarged side sectional view of a main part configuration of a grindstone and a dress electrode showing an operation state following FIG. 7;

FIG. 9 is a side sectional view showing a main part of a conventional spherical surface generating method.

FIG. 10 is a side sectional view showing an operation state of a conventional spherical surface forming method different from FIG. 9;

FIG. 11 is a side sectional view showing an operation state of the spherical surface generating method subsequent to FIG. 10;

FIG. 12 is a side sectional view showing an operation state of the spherical surface generating method subsequent to FIG. 11;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductive grinding tool 2 Grinding stone 3 Grinding surface 4, 17 Dress electrode 5 Power supply device 6 Weakly conductive coolant 7 Work 10 Driving means 11 Electrode brush 13 Switching SW 14 Coolant nozzle 16 Chuck

Claims (4)

(57) [Claims] A conductive grinding tool provided with a grinding surface formed in the same shape as the curvature of a workpiece; a dress electrode disposed at a position facing the grinding surface of the conductive grinding tool; Coolant supply means for supplying a weakly conductive coolant between the conductive grinding tool, and the polarity to be applied to the dress electrode, when performing electrolytic dressing of the grinding surface of the conductive grinding tool, and the electrode surface of the dress electrode. And a polarity switching means for switching between when and when performing the electrolytic machining of the spherical surface. 2. A method according to claim 1, further comprising: supplying a weakly electric coolant between a ground surface of a conductive grinding tool for grinding a workpiece and a dress electrode disposed at a predetermined distance from the ground surface. And applying a cathode to the conductive grinding tool to subject the dress electrode to electrolytic machining. 3. The method according to claim 1, further comprising: supplying a weakly electric coolant between a ground surface of a conductive grinding tool for grinding a workpiece and a dress electrode disposed at a predetermined distance from the ground surface. An anode, a step of electrolytically processing the dress electrode by applying a cathode to the conductive grinding tool, and a cathode to the dress electrode, applying an anode to the conductive tool, respectively. A step of electrolytically dressing the ground surface. 4. A weakly electric coolant is supplied between a grinding surface of a conductive grinding tool for grinding a workpiece and a dress electrode provided at a predetermined distance from the grinding surface and facing the dressing electrode. Performing electrolytic dressing of the grinding surface of the conductive grinding tool or electrolytic processing of the electrode surface of the dress electrode by switching each polarity of the conductive grinding tool and performing the electrolytic dressing of the grinding surface of the conductive grinding tool. A method for generating a spherical surface, comprising processing a workpiece on a ground surface of a conductive grinding tool.