JPS6144775Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to precision grinding of glass such as optical lenses, and particularly to a grinding tool suitable for precision grinding of glass that is a hard glass material and difficult to grind.

The production of optical lenses usually involves first cutting and molding the glass material, then grinding it into the approximate shape of the lens with a grindstone using coarse abrasive grains, followed by precision grinding to smooth the surface, and finally, cerium oxide. A mirror finish is performed using, etc.

Precision grinding is also commonly referred to as sand grinding, and there are two methods: lapping using a slurry of abrasive material, and a method using a molded body (fixed abrasive grains) in which abrasive material is bonded with metal etc. There is. The former is difficult to process the slurry after polishing;
The latter method has been attracting attention in recent years due to the poor working environment.

The method using a molded body has a higher utilization rate of abrasive material compared to the pouring of slurry in the case of lapping, so expensive diamonds can be used, and one of its characteristics is that it has high grinding efficiency. It is. This specific method involves attaching a molded body to a polishing plate having a surface made to match the concave or convex surface of the target lens, and grinding the molded body by rubbing the lens against the molded body.

A conventionally known diamond molded body is a diamond pellet made by mixing diamond powder and copper metal powder and sintering the mixture. A large number of these pellets are applied to a polishing plate at predetermined intervals and used.

Furthermore, some diamond moldings are made into a single sheet and used by pasting this onto a polishing plate. In this case, since the polishing plate usually has a convex or concave surface, a notch is provided at the periphery of the sheet so that the sheet can be brought into close contact with the polishing plate.

Grinding performance is not a problem when many diamond pellets are applied because there are many edges around the pellets, but it is not only troublesome to make and apply many pellets, but also difficult to use. Easy to peel off. Since pellet wear is greater in the center of the polishing plate, the curvature of the polishing surface gradually shifts during use. When this deviation reaches a certain limit, the entire pellet must be replaced. Therefore, the work required for this replacement cannot be ignored.

The one using a sheet does not have the above-mentioned drawbacks, although there is some waste at the notch. However, the grinding performance is not sufficient.

The present invention was devised under the above circumstances, and aims to provide a grinding tool that has high grinding performance, is particularly suitable for grinding hard glass, and is easy to handle.

That is, in the present invention, a large number of small holes are provided in a mixed sintered and rolled sheet of diamond and copper-tin alloy powder, and furthermore, notches are provided in the periphery of the sheet, and this is attached to a polishing plate.

A detailed description will be given below with reference to the drawings.

Fig. 1 is a sectional view of the grinding machine of the present invention, and Fig. 2 is a plan view of a sheet used for this.

The grinding tool 1 is made up of a polishing plate 11 and a sheet 2 pasted thereon. Although the polishing plate has a convex surface in the figure, it may also have a concave surface.

A large number of small holes 23 are provided in the sheet 2. The diameter of the small holes is suitably about 1 to 5 mm, and the total area of the small holes is preferably about 10 to 40% of the area of the sheet (excluding cutouts).

A notch 21 is provided in the sheet. This usually has a shape extending from the periphery of the sheet toward the center, but it is not necessarily limited to a straight line shape, but can also be a curved shape. The number of notches is appropriately determined in consideration of the size of the polishing plate, its curvature, etc. so that the sheet will come into close contact with the polishing plate.

In the figure, a notch 22 is provided that passes through the center of the sheet, but this is particularly effective when the length of the notch from the periphery is short or when the polishing plate has a large degree of curvature. , it is desirable to provide.

The sheet used in the present invention is made by sintering and rolling a mixture of diamond powder and copper-tin alloy powder.

The alloy powder is mainly composed of Cu, with a small amount of Sn added to adjust the hardness. This again
Adding a small amount of Ni or Ti improves the wettability between the alloy and diamond powder, improving grinding performance. However, since the addition of Ni and Ti increases the hardness of the copper alloy, it is necessary to adjust the amount of addition of Sn and to determine the range depending on the purpose of use.
Generally, it is desirable to add Ni and Ti at 5% or less.

If the metal is too soft, such as Cu alone, the grinding performance will deteriorate, while if the metal is too hard, it will lack flexibility and will not fit well when used attached to a polishing plate.

Therefore, the desirable alloy composition is Cu85-95%, Sn5
~10%, Ni or Ti alone or in an alloy up to 5%.

In the present invention, the sheet made of the alloy and diamond may further contain solid lubricant powder. As the solid lubricant, fine powder of graphite, molybdenum disulfide, boron nitride, loite, mica, etc. can be used. A suitable range for these is 1 to 5%. The solid lubricant has the effect of preventing the occurrence of scratches on the glass, and also improves the grinding performance by preventing the solid lubricant from falling off during grinding, creating pores, and clogging.

Next, the manufacturing method of the rolled sheet will be described.

Alloy powder is 180μ or less, diamond powder is 2
~40μ, and the suitable mixing ratio of the two is 100 parts by volume of the former and 4 to 80 parts by volume of the latter. Mix both well, place in a mold, and sinter while applying light pressure. Since the sintered body is then rolled, this sintering may be performed at a temperature of 750 to 900°C for about 30 minutes. The atmosphere at this time can be vacuum, inert, or reducing, but a reducing atmosphere is preferable in order to prevent oxidation of metals, diamond powder, etc. and improve sinterability.

Rolling can be performed at room temperature. For rolling, unidirectional rolling is preferred in order to finish the sheet uniformly.

These rolling conditions are such that the porosity of the rolled sheet is 5 to 5.
It is set to fall within the 20% range. Since this porosity increases when a solid lubricant is added, the porosity can also be adjusted by this.

After rolling, small holes are made using a press or the like, and notches are provided. When drilling holes, small burrs may occur, oil from rolling may adhere, etc.
And since it was a little hardened, I finished the sheet at 750°C.
Anneal at ~900 °C for 30 min. The sheet thus produced may be pasted on the polishing plate with adhesive.

The grinding tool of the present invention has a large number of small holes, and since the grinding performance at the edges of these holes is high, the amount of grinding per unit time is large. For reference, an example of glass being ground using this grinding tool is shown below.

Reference example 1 Mix 88% Cu, 9% Sn, and 3% Ni (by weight) alloy powder (125μ or less) and diamond powder (8 to 16μ) at a volume ratio of approximately 3:1, put it in a graphite mold, and heat it at 850
±20%, sintered under a load of 30g/ ^cm2 , thickness 0.45
A sintered body of mm was obtained.

Next, this sintered body is passed between rolling rolls at room temperature,
It was rolled to a porosity of 15% to form a rolled sheet with a thickness of 0.2 mm.

A sheet shown in FIG. 2 was manufactured from this rolled sheet. Seat diameter approximately 90cm, small hole diameter 2.5mm,
The spacing between the small holes is about 6 mm, and the width of the notch is 2 to 3 mm.

This sheet was attached to a convex polishing plate with a radius of curvature of 66 mm using adhesive, and a concave lens that had been ground to remove rough edges was ground, and the following results were obtained.

Polishing machine: Oscar type glass polishing machine Glass type: BK-7 60mmφ Lower plate rotation speed: 1500rpm Coolant: Polyethylene glycol type, 20x liquid Grinding amount for 10 minutes: 650μm Surface roughness after 10 minutes: Rmax3.5μm Glass grinding amount (μ) / Seat wear amount (μ): 47

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the glass precision grinding tool of the present invention, and FIG. 2 is a plan view of a sheet used in the tool. 11... Polishing plate, 2... Sheet, 21... Notch, 23... Small hole.

Claims (1)

[Scope of utility model registration request] A mixed sintered and rolled sheet 2 of diamond powder and copper-tin alloy powder is pasted on a polishing plate 11, and the sheet is made of glass with a large number of small holes 23 and cutouts 21 around the sheet. Grinding tools.