JPH04315573A - Grinding device - Google Patents

Abstract

PURPOSE:To perform dressing of a grinding wheel with simple constitution by stably exhibiting expected electrolytic dressing function on the surface of the grinding wheel. CONSTITUTION:The positive electrode of an electric power source 11 is connected to a feeder brush 12, and the negative electrode is connected to a nozzle 9. Electrolyte coolant in a liquid basin part 6 formed with the cup part 5a of a cup-like wheel 5 is electrified on the minus side, and an electric way from the cup-like wheel 5 to a spindle 7 through a grinding wheel 4 is formed. By supplying electric power from the electric power source 11 at grinding a lens 1, the electrolyte coolant supplied from the nozzle 9 is electrified, and the electrolyte coolant electrified in this way is let flow out through a gap G formed between the grinding wheel 4 and an opposed face part 2b. Electric current is let flow through the grinding wheel 4, bonding material on the surface layer of the grinding wheel 4 is electrolytically melted away, abrasive grains are floated up from the surface of the grinding wheel, and hence electrolytic dressing is performed.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a grinding device for grinding a workpiece such as a lens using a grindstone, and more particularly to a grinding device in which the grindstone is dressed using an electrolytic dressing method. It is something.

0002

[Prior Art] A grinding device for grinding lenses, etc. has a lens holder that holds the lens and an annular grindstone, and the grindstone is attached to a spindle, and the lens holder is connected to a rotating shaft. The lens is then ground by rotating the lens and the grindstone in opposite directions with the grindstone partially in contact with the processed surface of the lens, and sliding the grindstone along the processed surface of the lens. I'm trying to process it. When molding a lens into a spherical shape, the spindle is tilted at a predetermined angle with respect to the axis of the rotation axis of the lens holder, and when molded into a planar shape, the axis of the spindle is parallel to the axis of the rotation axis. Place it like this,
Perform grinding.

[0003] Here, a so-called metal bonded whetstone is usually used, in which a metal such as copper or iron is used as a bond material, and diamond powder as abrasive grains is mixed with this bond material. If this is repeated, the grinding wheel will become clogged with grinding debris, which will reduce grinding efficiency and cause seizures, which will affect grinding accuracy. In particular, when attempting to achieve a high mirror finish through this grinding process, the grain size of the abrasive grains needs to be made finer, which results in premature wear of the abrasive grains and even a small amount of grinding debris adhering to the grinding wheel surface. Clogging occurs. For this purpose, the grindstone must be dressed and sharpened. So-called electrolytic dressing is known as a method in which this dressing is performed continuously during the grinding process without using a mechanical dressing tool. In this electrolytic dressing, a power supply body with the grindstone as an anode and a cathode for dressing are provided facing each other, and a weakly conductive water-soluble grinding fluid is supplied between the two to remove the surface layer of the grindstone surface. The bond material in the surface layer is ionized, the bond material in the surface layer is electrolytically eluted, the abrasive grains are raised, and the abrasive grains exhibit a sharpening effect. If you perform electrolytic dressing in this way,
Since the blade can be fired continuously according to the wear of the abrasive grains, the desired grinding state can always be maintained, and the grinding finish can be performed with extremely high precision.

0004

By the way, in order to carry out the above-mentioned electrolytic dressing, conventionally, an annular negative electrode with a diameter larger than that of the grinding wheel is attached to the lens holder, and this electrode is Grinding wheels that are positively charged are placed facing each other with a predetermined gap between them, and a nozzle for supplying a weakly conductive grinding fluid is placed so as to face this gap, and the grinding fluid is sprayed from this nozzle to perform grinding. By charging the liquid to a negative polarity, a current was applied to the grindstone to ionize the bond material. In such a configuration, there is a problem that the grinding wheel surface can face the electrode only in a small area, and a sufficient dressing area cannot be obtained. Additionally, it is necessary to change the angle of the spindle used to rotate the grinding wheel depending on the curvature of the lens to be machined, but if you adjust the angle of this spindle, the position of the electrode must also be adjusted accordingly. Another drawback is that adjustment is extremely troublesome. Furthermore, since the grinding wheel and electrode are designed to rotate at high speed in opposite directions, the grinding fluid must be sprayed at a considerably high pressure from the nozzle toward the gap between the grinding wheel and the electrode. Otherwise, it would not be possible to stably supply the grinding fluid to this gap, which would increase the amount of grinding fluid consumed and also result in unstable dressing action.

The present invention has been made to solve the above-mentioned drawbacks and problems in the prior art, and its purpose is to stabilize the desired electrolytic dressing action with a simple configuration. It is an object of the present invention to provide a grinding device that can be operated in a state of

[0006]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides a work holder for holding a work,
A grinding wheel consisting of an annular member containing abrasive grains mixed with a conductive bond material, which grinds the surface of the workpiece by slidingly contacting the workpiece;
The grindstone is fixed to the tip of the cup member, and the cup member has an insulating layer formed on the inner surface, a spindle that rotationally drives the cup member, and a nozzle that supplies electrolyte coolant into the cup part, and the workpiece in the work holder is By forming an opposing surface part around the mounting part that faces the part of the grindstone that does not contact the workpiece with a predetermined gap, the inside of the cup member is made into a reservoir part of the electrolyte coolant. At the same time, the gap is used as a liquid passageway,
Further, the present invention is characterized in that the nozzle is used as a cathode, the cup member is used as an anode, and a predetermined voltage is applied between them to perform electrolytic dressing on the grinding surface of the grindstone.

[0007]

[Operation] By adopting such a configuration, a reservoir for electrolyte coolant is formed within the cup member, and the electrolyte coolant always flows out reliably from the gap between the grinding wheel and the facing surface of the work holder. A flow path is formed. By using the nozzle as the cathode side electrode, the electrolyte coolant flowing out from the nozzle is charged. In addition, by using the cup member as an anode, when the electrolyte coolant flows out of the gap, a current flows due to the potential difference between the grinding wheel and the electrolyte coolant, and the bond material on the surface layer of the grinding wheel surface is electrolytically eluted. This allows the abrasive grains to exert their cutting action.

[0008] Therefore, of the surface of the grindstone used to grind the work, the part facing the opposing surface of the work holder other than the part that is in contact with the work is always in contact with the negatively charged electrolyte coolant. Because of this, the dressing action can be exerted in a stable state over a wide range, and even if the angle of the spindle that drives the grinding wheel is changed, there is no need to make any special adjustments on the work holder side. .

[0009]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings. In FIG. 1, reference numeral 1 indicates a lens as a workpiece, and this lens 1 is attached to a lens receiving portion 2a of a lens holder 2. As shown in FIG. A rotating shaft 3 is integrally provided on the lens holder 2 . In addition, 4 indicates a whetstone, and this whetstone 4
A so-called metal bond grindstone is used in which diamond powder as abrasive grains is mixed with a metal such as iron or copper as a bond material. The grindstone 4 is formed in an annular shape and is fixed to the tip of the cup portion 5a of the cup-shaped wheel 5. The interior of this cup portion 5a becomes a reservoir portion 6 for electrolyte coolant.

Inside the cup-shaped wheel 5 is a spindle 7.
is screwed in, and a sealing nut 8 is attached. The base end of the spindle 7 is equipped with a rotational drive means such as a motor (
(not shown) is connected, and the spindle 7 is rotationally driven by this rotation driving means, and the cup-shaped wheel 5 is rotated together with the spindle 7. A nozzle 9 is inserted into the spindle 7, and the tip of the nozzle 9 extends through the sealing nut 8 and opens into the cup portion 5a. Then, from the nozzle 9, an electrolyte coolant having the functions of an electrolyte, a grinding fluid, and a cooling function for the grinding wheel 4 is supplied to the liquid reservoir 6 in the cup part 5a. There is. In addition, the lens receiving part 2 in the lens holder 2
The surface around a is a facing surface portion 2b that faces the grindstone 4, and this facing surface portion 2b is lower than the outer peripheral edge portion of the lens 1. Therefore, a step is created between the surface of the lens 1 and the facing surface portion 2b, and a gap G is created between the surface of the lens 1 and the facing surface portion 2b, and this gap G becomes a flow path through which the electrolyte coolant flows out from the cup portion 5a. Further, the nozzle 9 is held in a non-rotating state, and a bearing 10 made of an insulating rotating ring is interposed between the nozzle 9 and the sealing nut 8 near its tip.

[0011] Then, with the grindstone 4 in contact with the lens 1, the rotating shaft 3 is rotated, and the spindle 7 is rotated.
By rotating and driving the lens 1, the grindstone 4 comes into sliding contact with the surface of the lens 1 and grinds it. Here, by tilting the spindle 7 with respect to the rotation axis 3, the lens 1 can be machined into a spherical state, and when the spindle 7 is made parallel to the rotation axis 3, the lens 1 can be ground into a flat state. . Furthermore, by controlling the angle of inclination of the spindle 7 with respect to the rotation axis 3, the lens 1 can be ground into a spherical shape with a desired radius of curvature. During the grinding process of the lens 1 described above, the electrolyte coolant is supplied from the nozzle 9 into the cup portion 5a, and the electrolyte coolant in the liquid reservoir 6 inside the cup portion 5a is used to drive the grinding wheel. 4 can be cooled. Further, the electrolyte coolant supplied to the liquid reservoir 6 flows out through a gap G formed between the opposing surface 2b of the lens holder 2 and the tip of the grindstone 4.

Here, in order to grind the lens 1 with the grindstone 4 efficiently and with high precision, the surface of the grindstone is sharpened while the grinding process continues, and this sharpening is performed using an electrolytic dressing method. It will be done. This electrolytic dressing is to ionize and elute the bond material on the grinding wheel surface of the grinding wheel 4 by passing an electric current through the grinding wheel 4. For this purpose, a power source 11 is provided. The anode (+pole) is connected to a power supply brush 12 provided on the cup-shaped wheel 5, and the cathode (-pole) is connected to the nozzle 9. By negatively charging the electrolyte coolant in the liquid reservoir 6 formed by the cup 5a, an electric path is formed from the cup-shaped wheel 5 to the spindle 7 via the grindstone 4. Therefore, the spindle 7 interposed between the cup-shaped wheel 5 that is charged on the positive side and the nozzle 9 that is charged on the negative side is formed of an electrically insulating member, or the spindle 7 is
The cup-shaped wheel 5 and the nozzle 9 are electrically insulated by forming the cup-shaped wheel 5 and the nozzle 9 using a means such as a coating having an electrically insulating member on the outer circumferential surface or the inner circumferential surface of the nozzle.
Furthermore, an electrically insulating coating 13 is applied to the inner surface of the cup portion 5a.

Next, reference numeral 14 denotes a cleaning member, and this cleaning member 14 is constructed by protruding a cleaner head 16 from a mounting member 15 fixed to the sealing nut 8. It is made of a member that has electrical insulation properties, and as shown in Figure 2,
A pair of cleaner parts 1 that come into sliding contact with the inner and outer surfaces of the nozzle 9
6a and 16b, and these cleaner parts 16a and 16b exhibit a kind of snap action function and are mounted so as to sandwich the nozzle 9 therebetween. The sealing nut 8 to which the cleaning member 11 is attached rotates integrally with the spindle 7, and since the nozzle 9 is fixed in the rotational direction, the grinding work is performed by rotating the spindle 7. During the cleaning, the cleaning parts 16a and 16b are brought into sliding contact with the inner and outer circumferential surfaces of the nozzle 9 to prevent an insulating film from being formed on the surface of the nozzle 9 due to grinding debris from the lens 1. That's what I do.

With the above configuration, when power is supplied from the power source 11 during grinding of the lens 1,
The electrolyte coolant supplied from the nozzle 9 is negatively charged. The electrolyte coolant charged in this way flows out through the gap G formed between the grinding wheel 4 and the opposing surface portion 2b, and therefore, between the positively charged cup portion 5a and the grinding wheel 4. A potential difference is generated, and a current flows through the grindstone 4 based on this potential difference. As a result, the bond material on the surface layer of the grinding wheel 4 is electrolytically eluted and the abrasive grains are raised from the grinding wheel surface, thereby performing electrolytic dressing, and the sharpening by this electrolytic dressing is continuous in parallel with the grinding. It will be held on. Therefore, the lens 1 can be efficiently and precisely ground. In addition, since it is possible to constantly sharpen during processing, it can be used as an abrasive grain.
Even if extremely fine grinding is used, stable fine grinding can be performed without clogging.

[0015]The entire surface of the lens holder 2, other than the part where the grinding wheel 4 contacts the lens 1, facing the opposing surface part 2b serves as an outflow path for the electrolyte coolant. This allows for a wider dressing area. During machining, by continuously flowing the electrolyte coolant from the nozzle 9, the negatively charged electrolyte coolant constantly flows out from the gap G, ensuring that it is between the grinding wheel 4 and the grinding wheel 4. It is possible to create a potential difference over a wide area, making electrolytic dressing efficient.
Moreover, it can be performed stably.

If a negative potential is applied to the nozzle 9, substances contained in the electrolytic solution will be deposited on the surface of the nozzle 9 due to ionization tendency, but during rotation of the cup portion 5a, Since the cleaners 16a and 16b of the cleaning member 14, which rotate together with the cleaning member 14, constantly rub against the inner and outer circumferential surfaces of the nozzle 9, which is held in a non-rotating state, an insulating coating is formed on the surface of the nozzle 9. There will be no inconvenience caused by formation.

Furthermore, even if the inclination angle of the spindle 7 is changed in order to change the radius of curvature of the lens mounted on the lens holder 2, the grinding wheel 4 will not touch the opposing surface 2b of the lens holder 2.
As long as there is no contact with the lens holder, the flow path of the electrolyte coolant can be maintained by the gap G, so it is necessary to particularly adjust the members on the lens holder 2 side and other members in order to exert the electrolytic dressing effect. I don't. However, since the flow path cross-sectional area of the electrolyte coolant changes due to the gap G, if this flow path cross-sectional area changes significantly, the amount of electrolyte coolant supplied from the nozzle 9 may need to be adjusted. However, this flow rate control can be performed relatively easily.

In the above-mentioned embodiment, a convex lens is ground as a lens, but if a concave lens 1' is to be ground, the structure shown in FIG. 3 may be used. Here, when processing the concave lens 1', it is also necessary to form the opposing surface portion 2b' of the lens holder 2' into a concave curved shape to match the lens 1'. Further, the lens receiving portion 2a' may be made to match the shape of the lens 1'. However, the members on the processing tool side, such as the grindstone 4 and the spindle 7, may have the same configuration as those for grinding the convex lens 1. Further, although the nozzle is held in a non-rotating state, it may be one that rotates integrally with the spindle. When the nozzle is also rotated in this way, it is necessary to connect the nozzle to the power source via a power supply brush or the like.

[0019]

[Effects of the Invention] As explained above, the present invention forms an opposing surface portion around the work mounting portion of the work holder that faces the portion of the grindstone that does not contact the work with a predetermined gap. A cup part forming a reservoir for electrolyte coolant is provided at the tip of the spindle through which a nozzle for supplying electrolyte coolant is inserted, and a grindstone is fixed to the tip of this cup part, and the nozzle is connected to the cathode. year,
The cup part is used as an anode, and by applying a predetermined voltage between them, the grindstone is sharpened by electrolytic dressing. By continuously flowing electrolyte coolant from the nozzle, it becomes negatively charged. The electrolyte coolant always flows out from the gap formed by facing the opposite surface of the work holder other than the part where the grinding wheel contacts the work, and electrolytic dressing can be performed efficiently and stably. Furthermore, even if the spindle is tilted depending on the shape of the processed surface of the workpiece, there will be no particular problem in exerting the electrolytic dressing effect.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the configuration of a lens grinding device showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of the configuration of a nozzle cleaning mechanism.

FIG. 3 is an explanatory diagram of the configuration of a lens grinding device showing a second embodiment of the present invention.

[Explanation of symbols]

1,1' lens 2, 2' Lens holder 2b, 2b' Opposing surface part 3 Rotation axis 4 Whetstone 5 Cup-shaped wheel 5a Cup part 6 Liquid reservoir 7 Spindle 9 Nozzle 11 Power supply 12 Power supply brush 13 Coating 14 Cleaning member G Gap

Claims (1)

[Claims] [Claim 1] Consisting of a work holder that holds a work, and an annular member in which abrasive grains are mixed with a conductive bond material,
A grindstone for grinding the surface of a workpiece by sliding on it; a cup member having the grindstone fixed to its tip and an insulating layer formed on its inner surface; a spindle for rotationally driving the cup member; and an electrolyte in the cup part. a nozzle for supplying coolant, and by forming an opposing surface part around the work mounting part of the work holder to face a part of the grindstone not in contact with the work with a predetermined gap. , the interior of the cup member is used as a reservoir for electrolyte coolant, and the gap is used as a liquid passage, further, the nozzle is used as a cathode, and the cup member is used as an anode,
1. A grinding device characterized in that a predetermined voltage is applied during this period to electrolytically dress the grinding surface of the grindstone.