JPS61111885A - Molding for grinding - Google Patents

Abstract

PURPOSE:To increase the grinding ability of a molding for grinding and also to decrease the wear by forming the molding by means of sintering of a mixture composed of a copper-tin systemic powder, powder of hard but brittle metal, and abrasive grains. CONSTITUTION:Abrasive grains (e.g., diamond powder) are mixed with a mixture composed of a copper-tin systemic powder (e.g., copper-tin alloy atomizing powder), powder of hard but brittle metal (e.g., low-carbon ferro molybdenum). By molding this mixture in sintering process, a molding having great grinding ability and of hardly subject to wear is obtained.

Description

[Detailed Description of the Invention] ,,-1-1! - The present invention relates to a sintered compact for grinding (hereinafter referred to as a sintered compact), particularly a metal pound sintered compact suitable for surface precision grinding and grinding with a cutter blade. Grinding in the present invention is a general term including polishing and cutting.

J Metal pound sintered bodies conventionally used for the above purposes, especially diamonds)'l! The main sintered compacts using boron nitride as grinding abrasive grains (hereinafter referred to as super-grinding abrasive grains) are copper-tin based pounds. In this copper-tin based pound sintered body, the grindability (grinding force) is improved by increasing the tin content, but the material is hard and brittle, and the sintered body itself has the disadvantage of increased wear. This is thought to be because if the pound portion is made of a uniformly brittle metal, the holding force for the abrasive grains will not be sufficient.

The method for manufacturing the sintered compact is generally a powder compaction method of a mixture of metal powder and abrasive grains. With this method, it is not easy to polish the surface of the glass or produce a thin sheet-like sintered body for use as a cutter blade, and it is also economically extremely inefficient.

m The present invention provides a sintered compact with large grinding force and low wear, that is, grinding ratio (grinding M-/wear amount of sintered compact)
To provide a sintered compact with a large size, and furthermore, a thin sheet-like sintered compact is easily produced, which is a sintered compact of hard and brittle metal powder (hereinafter referred to as hard brittle metal powder) and grinding abrasive grains. contains a small amount of nickel.

In the present invention, the copper-tin metal powder used is, for example, an atomized copper-tin alloy powder. The particle size is suitably less than +00 mesh, preferably less than 150 mesh. A tin content of 2 to 30% by weight in this metal is suitable for use. If the weight is less than 2, the hardness will be insufficient,
The grinding force decreases, and if it exceeds 30% by weight, the metal becomes brittle and the abrasive grain retention becomes insufficient. Further, it becomes difficult to form a sheet by rolling, which will be described later. This copper-tin metal may be alloyed in advance, or may be a mixture of respective metal powders.

The hard brittle metal powder preferably has a Vickers hardness of 500 or more and a brittleness of 15 kg/mrrf or less in Charpy impact value.

A suitable content thereof is 5 to 30% by weight based on the total amount of metal. If it is less than 5%, the effect will not be sufficient, and if it exceeds 30%, the metal phase will become too brittle and the sintered compact will suffer from severe wear during grinding. In addition, rolling is difficult in terms of manufacturing method.

In the present invention, the grinding ratio is increased by adding a hard brittle metal because the hard brittle metal powder is dispersed and sintered in the metal phase without weakening the strength of the metal phase that becomes the bond as much as possible during grinding. Il! ! The brittle metal is chipped minutely, so even if the abrasive grains wear out, the tips of the abrasive grains always protrude from the surface of the sintered compact, so good grinding power is maintained, and the metal phase is hard and brittle. It is presumed that this is because the strength of the molded body does not decrease significantly even if metal is added, so the wear of the molded body is not large, and the materials used include elementary ferromolybdenum, high carbon ferrochrome, sendust, martensitic (for example, 13% or 18% Cr) stainless steel, and stellite. The particle size of these hard brittle metal powders is preferably 150 mesh or less.

In the second invention, the addition of nickel, nickel and tin form an intermetallic compound, which is dispersed in the bond and has the effect of making the bond metal harder and stronger. Nickel may be alloyed with copper and tin in advance, or may be added separately as nickel powder.

In the case of nickel powder, a fine powder of about 100 mesh or less is preferable in order to uniformly disperse the intermetallic compound with tin, and for example, a powder made from nickel carbonyl is preferable. If the content of Ni-N is too high, the metal that becomes the bond tends to become too hard and brittle.
There are many difficulties with the rolling method. For this reason, nickel is preferably contained in an amount of 0.2 to 5% of the total amount of metal. Even when nickel is added, the hard and brittle metal acts differently from nickel, so the type and amount of nickel added can be used as is.

That is, a preferable composition of the second invention is such that nickel is 0.2 to 5% by weight, hard brittle metal is 5 to 30% by weight, and the balance is copper-tin metal, and the tin content is the same as that of the first invention. Similar to invention.

In the present invention, the sintered compact can contain short fibers m (including whiskers). The inclusion of fibers strengthens the metal that serves as the bond, thereby reducing wear during grinding of the sintered compact, resulting in a lower grinding ratio.

As the fibers, inorganic fibers such as carbon, silicon carbide, silicon nitride, and alumina are preferred. As mentioned above, these include whiskers.

Short fibers are used to improve dispersibility in the metal, and the length of the fibers is preferably about 500 gm or less, preferably 50 to 200 gmk. The amount added may be small, preferably 0.01 to 2% by volume in the sintered compact. If the amount is too large, the grinding force of the sintered body will be reduced.

Next, the grinding abrasive grains used in the molded article of the present invention will be explained.

The abrasive grains are usually super-abrasive grains or those mixed with other general grinding grains (hereinafter referred to as "general grinding grains") in order to uniformly finish the ground or cut surface. Of course, depending on the purpose, general grinding abrasive grains may be used.

A typical example of super-grinding abrasive grains is 174-200.
gm of diamond and/or cubic boron nitride are mixed in the sintered compact at a concentration of 0.3 to 10% by weight. These abrasive grains may be used alone or their surfaces may be coated with nickel, copper, tin, etc., and coated abrasive grains have better wettability with metals and can be mixed with a wide variety of abrasive grains.

- As general grinding abrasive grains, carbides such as silicon carbide and tungsten carbide, oxides such as aluminum oxide and silicon oxide, nitrides such as silicon nitride, and borides such as boron carbide and aluminum halide are preferably used. be done. Although these general grinding abrasive grains are softer than super-grinding abrasive grains and have inferior grinding properties, they have the effect of erasing the streaks peculiar to fixed abrasive grains and the dressing effect of preventing clogging of the sintered body. In order to fully achieve these effects, it is necessary to use super-abrasive grains and -
・It is desirable to determine the particle size and addition amount of general grinding abrasive grains. These general grinding abrasive grains are generally 0.1 μm to 50 μm.
About 0gm is used, and the appropriate amount is about 0.5 to 20% by weight in the sintered compact, but for example, if the work material is brittle, It is preferable to add general grinding abrasive grains finer than this 175 times to 175 times, and if it is viscous, add the same amount to twice as much general grinding abrasive grains that are the same as or coarser than the super-grinding abrasive grains.

The present invention is a sintered abrasive molded body in which the above-mentioned metal powder and abrasive grains are sintered into a single body, and this includes a sheet-shaped molded body formed by rolling. The thickness of the as-sintered product is arbitrary, but the thickness of the rolled product is usually 0.1~
A thickness of approximately I n+n+ is used.

The method for producing the sintered compact of the present invention is to thoroughly mix grinding abrasive grains with the metal powder mentioned above, and if fibers are used, mix them together, and then place the mixture in a mold, for example, and sinter it while heating and pressurizing. Sintering is suitably performed at a temperature of 700 to 950°C for about 30 to 60 minutes. The atmosphere at this time can be vacuum, inert, or reducing, but vacuum or reducing atmosphere is preferable in order to prevent oxidation of metals, super-grinding abrasive grains, etc. and improve sinterability. The sintering pressure may be, for example, about 0.5 to 1 kg/cm' even when the sintered compact is used without rolling, and this pressure should not be that high when the sintered compact is rolled next time. For example, 50/g/c
It may be about m'. Rolling can be performed at room temperature.

For rolling, unidirectional rolling is preferable in order to finish the sintered body uniformly, but if you dislike the anisotropy of rolling, cross 2-directional rolling is preferred.
You can also go in the direction. Although rolling generally reduces the porosity, this can be adjusted, for example, by changing the amount of abrasive grains added or the grain size.

Rolled products usually have oil attached to them, and are slightly hardened or deformed due to strain.
It is recommended to anneal for about 60 minutes. Further, when processing the rolled body, it is preferable to process it before this annealing. During surface precision grinding, the sintered bodies created in this way are attached to a surface plate with thermosetting adhesive or rubber adhesive, etc. It can be used for grinding ceramic sintered bodies, and by setting it on a counter, it can be used for cutting precious stones, marble, granite, various single crystals, and fine ceramic sintered bodies.

Next, the present invention will be explained by referring to examples.

Example 1 Atomized bronze powder of 100 mesh or less (tin content 2
10 to 20 pLI1 to 89.5 parts by weight of metal powder mixed with 75 parts (0 weight%) and 25 parts by weight of low carbon ferromolybdenum (No 135.2%) of 150 mesh or less.
1. Mix 0.5 weight of diamond powder with cotton, put it in a mold, and heat it in a hydrogen gas atmosphere at 850±15°C, 145g/c.
It was sintered for 45 minutes under the conditions of m'.
A sintered body of 4 cm and 1 m111 in thickness was obtained. Next, this sintered body was passed between rolling rolls at room temperature to form a rolled body having a thickness of 0.2 mm.

This rolled body was punched to a diameter of 100 mm to obtain a sheet having four incisions 2.5 mm wide and 40 mm long at equal intervals from the periphery. This sheet was heated to 850°C in a hydrogen atmosphere.
:l: Annealed at 15°C for 30 minutes.

I was able to attach this sheet to a flat polishing plate using rubber adhesive. When this grinding tool was used to grind flat glass having a surface roughness Rmat = 18 gm after rough grinding, the following results were obtained.

Polishing machine: Oscar type glass polishing machine glass
Species: BK-7, 70X70mm Kanzashi Load: 5
00g/cm' Lower/lower rotation speed 400rpm - Run 1: 20x ethylene glycol solution for 5 minutes Grinding amount: 200pH 1 Surface texture after 5 minutes: Rmax = 21Lm Grinding ratio [-
Grinding amount (gm) / Sea I/wear it: (gm) ): 100 Comparative Example 1 99.5 parts by weight of the same atomized bronze powder as in Example 1 and 0.5 parts by weight of diamond powder were mixed and carried out. A sheet was produced in the same manner as in Example 1. The same grinding test as in Example 1 was conducted using this, and the results are as follows.

Amount of grinding for 5 minutes = 150km Surface roughness after 5 minutes: Rmar = 1.8μm grinding
Cutting ratio 285 Example 2 7 tomized bronze powder with a mesh size of +00 or less (tin content 1
5% by weight) 73 parts by weight, 24 parts by weight of white cast iron of 150 mesh or larger (carbon content 8% by weight), and an average grain size of 3 to 7μ
3 parts by weight of nickel powder of m was added.

To 96.5 parts by weight of this mixed powder, 2 parts by weight of 70-90 μm Tiremond powder and 1.5 main vertical parts of 50-100 μm silicon carbide powder were added, and in the same manner as in Example 1, 880± 40 at 15°C and 55g/cm'
Sintered for minutes, length 17cm, width 14cm, thickness 0.8mm
A sintered body was obtained. The following rolling and annealing were performed under the same conditions as shown in Example 1, with a thickness of 0.3 mm and an outer diameter of 150 mm.
A C.I. mm and inner diameter of 50.8 mm were obtained.

This sheet] was used as an abrasive molded body, and a commercially available diamond resin blade (diamond grain size #230/270
, dimensions 150150.8mmφ It has been shown that it has good performance.

Table 1. Cutting test conditions Cutting machine: Creep feed forming grinder manufactured by Kaihon Kosakusho Number of revolutions: 3,18 Orpm Table speed: 20 mm/sin Depth of cut: 1, 3, 5 m
Grinding fluid: Water-soluble chemical type (60 times diluted) Work material: Silicon carbide pressureless sintered compact Cutting method: Down cut (blank below) Table 2. Cutting test results (Note 1) The amount of chipping is the average value obtained by observing the cut surface with a universal projector and measuring 10 points with large chipping acid (the size of the chipping around the cut surface).

(Note 2) Amount of wear of the abrasive compact when cutting 400 cylinders in order of depth of cut of 3 (blank below) Example 3 Atomized bronze powder of 100 mesh or less (tin content 2
0% by weight) and low carbon ferromolybdenum of 150 mesh or less in a ratio of 75:25 by weight.
~2 Gin] diamond powder (0.5% heavy water) and carbon fiber (diameter 5~10gm, length 100μm) 5% by volume were mixed and placed in a mold at 850±15°C in a hydrogen gas atmosphere.
Sintered for 45 minutes under the condition of 45g/cm', length 17cm
A sintered body with a width of 14 cm and a thickness of 1 m was obtained. Next, this sintered body was passed between rolling rolls at room temperature to a thickness of 0.2 m.
It was made into a rolled body of m. This rolled body is punched out and has a diameter of 100 m.
A sheet having mφ of 2.5 mm in width and 40 mm in length was obtained at four locations. This sheet was placed in a hydrogen atmosphere for 8 hours.
Annealed at 50±15°C for 30 minutes.

This sheet was attached to a flat polishing plate using a rubber adhesive. When this grinding tool was used to grind a flat piece of glass with a surface roughness Rll1ax = 181Lm after rough grinding, the following results were obtained.

Amount of grinding for 5 minutes: 250 #L11 Surface texture after 5 minutes: Rmaw = 2.3 grn Grinding ratio [= Amount of glass grinding (gm) / Amount of sheet wear (pm)): 105 Effects of the invention Grinding according to the present invention Thin 1. A molded body for grinding with a high grinding ratio can be obtained and is particularly useful for glass grinding. % rolled body can be easily obtained.

Claims (6)

[Claims] (1) A molded body for grinding made by sintering copper-tin metal powder, hard and brittle metal powder, and grinding abrasive grains. (2) A molded body for grinding made by sintering copper-tin metal powder, nickel powder, hard and brittle metal powder, and grinding abrasive grains. (3) A molded article for grinding by sintering according to claim 1 or 2, which contains short fibers. (4) A molded body for grinding by sintering according to claims 1 to 3, which is a rolled body. (5) A compact for grinding by sintering according to claim 1 or 2, wherein the grinding abrasive grains are diamond or cubic boron nitride. (6) A compact for grinding by sintering according to claim 1 or 2, wherein the grinding abrasive grains are a mixture of diamond or cubic boron nitride and other grinding abrasive grains.