JPH03264263A - Porous metal bond grinding wheel and manufacture thereof - Google Patents

Abstract

PURPOSE:To sharply improve the cooling effect of a grinding wheel and to perform polishing in a half-dry state by containing grinding liquid and cutting oil in blow holes by dispersing porous potassium silicate particles in the abrasive grain layer of a porous metal bond grinding wheel. CONSTITUTION:A porous metal bond grinding wheel is formed such that porous potassium silicate particles 3 are uniformly dispersed in a metal coupling phase 1 togetherwith superabrasive grains 2. In the so formed porous metal bond potassium silicate grinding wheel, a number of blow holes are formed in the porous potassium silicate particles 3 dispersed in an abrasive grain layer, besides since a ratio in which the internal blow holes 3 in the identical particle 3 are intercommunicated is high, grinding liquid in the blow hole is sucked through a capillary action wherein the blow hole makes contact with the grinding liquid, and the cooling effect of a grinding stone is sharply improved. By previously immersing the abrasive grain layer in the grinding liquid and cutting oil and containing the liquid and oil in the blow hole, grinding in a half-dry state is practicable.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a metal bond grindstone for polishing or grinding work materials such as cemented carbide, ceramics, ferrite, glass, etc. and a method for manufacturing the same. , relates to improvements for increasing the porosity of an abrasive grain layer and promoting the self-sharpening action of superabrasive grains.

"Prior Art" A typical metal bonded grindstone is formed by uniformly dispersing superabrasive grains in metal powder, molding the powder together with an alloy, and then press forming and sintering (or hot pressing).

This type of metal bonded grindstone has a much higher bonding phase strength than a resinoid bonded grindstone or a vitrified grindstone, and has a strong abrasive grain retention ability. Therefore, although the life of the grinding wheel is long, there is a problem in that the worn abrasive grains on the cutting edge are difficult to fall off, the grinding resistance increases, the sharpness deteriorates relatively quickly, and the dressing frequency has to be increased.

In order to improve this drawback, conventionally, carbon powder or the like is added as a filler to the binder, which moderately reduces the abrasive grain holding power of the binder phase, causing worn abrasive grains to fall off and new abrasive grains to be exposed. Some methods are used to promote the so-called self-sharpening action and prevent deterioration of sharpness.

``Problem to be solved by the invention'' By the way, if it were possible to form a large number of pores inside the abrasive grain layer, it would be possible to impregnate these pores with grinding fluid to improve the cooling performance of the grinding wheel, or to create a large number of chips on the grinding surface. It is expected that excellent effects such as generating pockets and improving chip discharge performance will be obtained.

However, conventionally used fillers such as carbon powder all have a dense particle structure and do not have the effect of forming pores inside the abrasive grain layer, so it is difficult to obtain the above effects. I couldn't.

"Means for Solving the Problems" The present invention has been made to solve the above problems, and the configuration thereof will be specifically explained below.

The porous metal bonded grindstone according to the present invention is characterized in that porous calcium silicate particles are uniformly dispersed together with superabrasive grains in the metal bonding phase.

This porous calcium silicate particle has the following properties: 5jOt: 50 to 80 wt%, CaO: lO to 40
vL%, AI, 0. :0.1 to 5 wt%, has a multi-valve shape with many pores inside, and has a high proportion of internal pores communicating with each other. This porous calcium silicate powder is commercially available, for example, under the trade name Fluorite R manufactured by Tokuyama Soda Co., Ltd., and the physical properties of Fluorite R are described below for reference.

Average particle size: 20-30μ, apparent specific gravity: 0.08-0
．． 12, PH: 8.5-9.1. Oil absorption: 4°O~6
00 (s+12/100g), adsorbed moisture: 8wt%
below.

Note that this type of porous calcium silicate powder has a
It has the characteristic of rapidly shrinking in a short period of time when heated above 0°C. For example, in the above-mentioned fluorite (2), the apparent specific gravity increases by more than three times at a temperature of 770° C., and pores corresponding to this shrinkage volume are formed in the abrasive grain layer.

The amount of porous calcium silicate powder added is from 3 to 3 in the abrasive layer.
It is said to be 35vo1%. In reality, it is desirable to change the amount added depending on the type of grinding wheel. For wheel-type grindstones that make line contact with the workpiece material, it is 3 to 20vo1%, and for cup-type grindstones that make surface contact with the workpiece material, it is IO to 35vo1%. Optimal. With cup-shaped grindstones, the self-generating action of the superabrasive grains is poor due to surface contact, and clogging is likely to occur. Therefore, it is necessary to promote abrasive grain drop-off or form chip pockets more easily than with a wheel-type grindstone. If the amount added is less than 3vol%, sufficient self-sharpening effect cannot be obtained. Moreover, if it exceeds 35 vol%, the decrease in strength of the binder phase cannot be ignored, and there is a possibility that the mold part of the abrasive layer may be distorted, resulting in a decrease in grinding accuracy.

As the metal binder, for example, Cu-Sn type, CuSn-
Co-based, Cu-Sn-Fe-Co-based, Cu-9nNi-based, or Cu-Sn-Fe-Ni-based binders, or binders in which P is added to these are suitable; in particular, Cu-9
The n-Co type and the Cu-Sn-Fe-Co type have the advantage of superior sinterability compared to others.

For both binders, the sintering temperature is approximately 400-700
℃ is preferable, and if the porous calcium silicate particles are contracted by raising the temperature to 750 degrees C. or higher after sintering, the pores can be enlarged.

To manufacture the grindstone, porous calcium silicate powder is
The metal binder powder and superabrasive grains such as diamond or CBN are mixed uniformly in a mixer, and the mixture is placed in a press machine together with an alloy and compacted as in the past.

At that time, the press pressure is preferably 10 to 9 IC1 in either cold press or hot press.If it is less than lOkgr/cm', a green compact with sufficient strength cannot be formed. 500kgf7cm”
If it exceeds this, the porous calcium silicate particles will be crushed and the pore-forming effect will be reduced. Within the above range, the porous calcium silicate particles (1) are compressed almost in proportion to the pressure (have continuous compression moldability), so a desired porosity can be selected by adjusting the pressing pressure.

When cold pressing is performed, after pressing, sintering is performed at the above sintering temperature to obtain a porous metal bonded grindstone. FIGS. 1 and 2 are enlarged cross-sectional views showing the abrasive grain layer in this state, where 1 is the metal bonding phase, 2 is the superabrasive grain, and 3 is the abrasive grain layer.
are porous calcium silicate particles. On the other hand, in the case of hot pressing, it is desirable that the molding temperature be 350 to 700°C.

In the porous metal bonded grindstone having the above structure and the manufacturing method thereof, a large number of pores exist inside the porous calcium silicate particles dispersed inside the abrasive grain layer, and the internal pores of the same particle communicate with each other. Since the grinding fluid has a large proportion of the grinding fluid, when it comes into contact with the grinding fluid, the grinding fluid is sucked into the pores by capillary action, greatly improving the cooling effect of the grinding wheel. Further, if the abrasive grain layer is immersed in a grinding liquid or grinding oil in advance so that it is included in the pores, it is also possible to perform semi-dry grinding.

In addition, the distribution density and size of the internal pores can be set arbitrarily by adjusting the amount of porous calcium silicate powder added and the molding pressure, so the liquid absorption can be freely controlled. It is.

In addition, since the porous calcium silicate particles 3 do not have ductility, they easily cause micro-fractures when they come into contact with the workpiece material during grinding and fall off from the binder phase 1, compared to carbon particles etc., leaving behind chips. A pocket is formed. By forming a large number of such chip pockets on the grinding surface, the evacuation of chips is significantly improved, the strength of the binder phase 1 is appropriately reduced, wear is accelerated, and the self-generation of the superabrasive grains 2 is promoted. The effect is enhanced.

In addition, the strength of the bonding phase of the grinding wheel can be adjusted steplessly by adjusting the amount of porous calcium silicate powder mixed, and it is also possible to impart elasticity to the abrasive grain layer, making it suitable for specific work materials and grinding conditions. can be done. Further, since the bonding phase l is softened, it becomes possible to perform grindstone shaping using a general grindstone as a grindable wheel, and shaping costs can be reduced.

Furthermore, the weight of the grindstone can be reduced, and the driving force can be reduced.

The abrasive layer after sintering is reheated at 750° C. or higher to shrink the porous calcium silicate particles 3 inside the abrasive layer as shown in FIGS. 3 and 4 (3A). , and then a large number of holes 4 may be formed. Since the pores thus formed are larger than the internal pores of the porous calcium silicate particles, the above effects can be further promoted.

Furthermore, after the porous calcium silicate particles are subjected to a well-known granulation process to increase their diameter, these composite particles may be used for manufacturing a grindstone. By doing this, the chip pockets formed at the spots where the particles have fallen out will be greatly reduced, and the chip discharge performance will be improved.

In addition, the abrasive grain layer does not contain porous calcium silicate powder, and if necessary, solid lubricants such as graphite powder and hBN powder, and hard particles or hard fibers such as SIC and Alyos are added. Good too.

"Example" Next, examples will be given to demonstrate the effects of the present invention.

(Example: Cup whetstone added with porous calcium silicate powder (2
A2 type) was manufactured under the following conditions.

Abrasive grain layer dimensions: Outer diameter 300iu
Main composition of porous calcium silicate powder: 5iOt:6
0wt% CaO: 20wt% Ale's: 0.5wt% Average particle size of the same powder: 25 μm Addition amount of the same powder: 1 Ovo 1% Cold press pressure crab 200 kg/cm” abrasive layer Sintering conditions: 600°C x 10 Time, Nt Atmosphere (Comparative Example 1) A cup-shaped grindstone having the same dimensions as in Example 1 and the same as above except that no porous calcium silicate powder was added was prepared.

Then, a double-headed grinding test was conducted using two of each of the above two grindstones under the following grinding conditions, and the grinding ratio and the power of the grinder required to drive the grindstones were measured. Note that the opposing grindstones were rotated in the opposite direction.

Work material: AI2.0. 92wt% Grinding wheel peripheral speed: l 500 x/+in.

Workpiece feed amount: 15 pieces/akin.

Cut Il: 0, 5x* on one side, 1.0+u on both sides
+ Work material dimensions: outer diameter 50 x inner diameter 10 (ring type) Number of processing: 15,000 pieces Grinding fluid: Chemical solution 50 times diluted The results are shown in Table 1.

On the example day shown in Table 1, the self-sharpening effect of the cutting edge was good, good sharpness was maintained, and the grinding wheel driving force was significantly reduced due to the small grinding resistance. In addition, since the sharpness improved, reduction in the grinding ratio was also prevented.

(Example 2) Nistrade grindstone A straight grindstone to which the present invention was applied was manufactured under the following conditions.

Abrasive layer dimensions: Outer diameter 200*zx width 15RI1. ×Thickness 5iz Particle size of diamond abrasive grain: #200 Concentration degree: 60 Metallic binder near 0wt%Cu-10wt$Ni-19,5wt$Sn
-0.5V Composition of P porous calcium silicate powder SiOt: 60 wt% CaO: 20 wt% AI, 0. : 4wt% Average particle size of the same powder: 25 μl Addition amount of the same powder: 20vo1% Cold press pressure crab I 50 kg/cy” Abrasive layer sintering conditions: 600°C XIO time, Nt atmosphere (Comparative Example 2) Example A straight whetstone having the same dimensions as in Example 2 and the same as in Example 2 except that no porous calcium silicate powder was added was prepared.

The following grinding tests were conducted using each of the above two grindstones, and the grinding ratio, grinder power, and surface roughness of the workpiece after grinding were measured. The results are shown in Table 2.

Work material: Cemented carbide (K2O) dyed rectangular parallelepiped + 001 shoulder
I 500+++ /sin table feed speed 25x
x/min Cross speed: 2 xi/pass Grindstone depth of cut:
0.010xz The dynamic force was significantly reduced, and the surface roughness of the workpiece was also significantly better than that of Comparative Example 2, indicating that the cutting quality was improved.

(Example 3): Cup-shaped grindstone A cup-shaped grindstone (6A2 type) to which the present invention was applied was manufactured under the following conditions.

Abrasive layer dimensions: Outer diameter 300s+s+x width 15xz Diamond abrasive grains: Particle size #140 Metallic binder: 50wL%Cu+50wt%SnPorous calcium silicate powder composition Si0. Near 5 wt% CaO: 15 wt% ALO3: 2 wt% Zn stearate 2 vol 1% added The average particle size of the same powder: 25 μl Added amount of the same powder: 30 vol 1% Hot press conditions: 450°C x I 00 kg/cm' 1 hour, N, Atmosphere (Comparative Example 3) A cup-shaped grindstone was prepared that had the same dimensions as Example 3 and was identical to Example 3 except that no porous calcium silicate powder was added.

The following grinding tests were conducted using each of the above two types of grindstones, and the grinding ratio, drive power of the grinder, and surface roughness of the workpiece after grinding were measured. The results are shown in Table 3.

Work material: TiC cermet 12xx×5xx Grinding wheel peripheral speed: 1000 x/sin.

Depth: 0.0IOs+x Workpiece swing speed: 3z/sin.

Grinding fluid: Chemical Ralue 93F 50 times diluted solution Table 3 As is clear from the above table, Example 3 has a grinding ratio equal to or higher than Comparative Example 3, but has excellent sharpness.
Driving power and surface roughness were significantly improved compared to Comparative Example 3.

(Example 4) Nistrade grindstone A straight type grindstone to which the present invention was applied was manufactured under the following conditions.

Abrasive layer dimensions, outer diameter 200cm x width 15ix Diamond abrasive grain: particle size #80 concentration 50 Metallic binder: 60wt%Cu-10wt%Ni-10wt%Fe-2
Composition of 0 wt% Sn porous calcium silicate powder SiO*: 55 wt% CaO: 30 wt% A1*Os: 0, 5 wt% This porous calcium silicate powder (particle size 20μ0 was mixed with an acrylic binder, #60 granulated powder was prepared, and 20 wt% of this granulated powder was added.

Hot pressing conditions: 600° C. x 200 kg/cm” for 1 hour, Nt atmosphere The shrinkage rate of the porous calcium silicate powder at this time was 1/4 of the initial cross-sectional area.

(Comparative Example 4) A straight type grindstone was created which had the same dimensions as Example 4 and was made the same as Example 4 except that no porous calcium silicate powder was added.

The following grinding tests were conducted using each of the above two types of grindstones, and the grinding ratio, drive power of the grinder, and surface roughness of the workpiece after grinding were measured. The results are shown in Table 4.

Cutting material 296wt% Altos 75xxx7F++xxF++x Grinding wheel peripheral speed: l 30 (1+/l1in.

Table feed speed: I Ox/win.

Cross speed: 2 zx/pass cut: 0
．． 025xx As is clear from the upper table of Table 4, the whetstone of Example 4 showed twice as good values as Comparative Example 4 in terms of driving power and surface roughness, and the sharpness was significantly improved. . Furthermore, in Comparative Example 4, cracks were observed on the machined surface of the workpiece. Comparative example 4
The reason why the grinding ratio is small is thought to be due to an increase in grinding resistance due to insufficient sharpness.

"Effects of the Invention" As explained above, according to the porous metal bond grindstone and the manufacturing method thereof according to the present invention, the following excellent effects can be obtained.

■ There are many pores inside the porous calcium silicate particles dispersed inside the abrasive grain layer, and a large proportion of the internal pores of the same particle are connected to each other, so when they come into contact with the grinding fluid, capillary action occurs. The grinding fluid is sucked into the pores, greatly improving the cooling effect of the grinding wheel. Further, if the abrasive grain layer is immersed in a grinding liquid or grinding oil in advance so that it is included in the pores, it is also possible to perform semi-dry grinding.

■ The distribution density and size of the internal pores can be set arbitrarily by adjusting the amount of porous calcium silicate powder added and the molding pressure, so liquid absorption can be freely controlled. .

■ Porous calcium silicate particles do not have ductility, so when they come into contact with a workpiece during grinding, they fall off more easily from the binder phase than carbon particles, etc., and a deep pocket is formed in their wake. By creating many such chip pockets on the grinding surface, the evacuation of chips is significantly improved, and the strength of the binder phase is appropriately reduced, accelerating wear and increasing the self-sharpening effect of the superabrasive grains. .

■ The strength of the bonding phase of the grinding wheel can be adjusted steplessly by adjusting the amount of porous calcium silicate powder mixed, and it is also possible to impart elasticity to the abrasive grain layer, so it can be tailored to specific work materials and grinding conditions. I can do it. Furthermore, since the binder phase is softened, it becomes possible to perform grindstone shaping using a general grindstone as a crusher pull wheel, and shaping costs can be reduced.

■ The weight of the whetstone can be reduced and the driving force can be reduced.

On the other hand, when heated to 750°C or higher in the grindstone manufacturing process, the porous calcium silicate particles dispersed in the abrasive grain layer contract, and pores larger than the pores are formed in their wake. ” It is possible to further promote the effect of two feet.

[Brief explanation of drawings]

1 and 2 are enlarged cross-sectional and vertical cross-sectional views of a porous metal grindstone according to the present invention, and FIGS.
FIG. 2 is a diagram similar to FIG. 1... Metal bonding phase, 2... Super abrasive grains, 3... Porous silicate particles, 3A... Contracted material, 4... Vacancies.

Claims (7)

[Claims] (1) In a metal bond grindstone having an abrasive layer formed by dispersing superabrasive grains in metal binder powder, compacting and sintering, porous calcium silicate particles are dispersed in the abrasive grain layer. A porous metal bond whetstone that is characterized by: (2) The porous calcium silicate powder is SiO_2
:50~80wt%, CaO:10~40wt%, Al
The porous metal bond grindstone according to claim 1, characterized in that it contains 0.1 to 5 wt% of _2O_3. (3) The metal binder is Cu-Sn based, Cu-Sn-
Co-based, Cu-Sn-Fe-Co-based, Cu-Sn-Ni
The porous metal bond grindstone according to claim 1 or 2, characterized in that it is either Cu-Sn-Fe-Ni type or Cu-Sn-Fe-Ni type. (4) The porous metal bond according to claim 1, 2, or 3, wherein the porous calcium silicate particles are contracted by subjecting the abrasive grain layer to a high-temperature heat treatment, and pores are formed in the traces of the shrinkage. Whetstone. (5) Mix super abrasive grains and porous calcium silicate powder in metal binder powder, and apply 10 to 500 kgf/cm^2
A method for producing a porous metal bonded grindstone, which comprises forming an abrasive grain layer by compacting and sintering at a pressure of . (6) The abrasive grain layer after sintering is reheated at 750°C or higher to shrink the porous calcium silicate particles inside the abrasive grain layer, forming a large number of pores in the wake. The method for manufacturing a porous metal bonded grindstone according to claim 5. (7) Manufacturing a porous metal bonded grindstone according to claim 5 or 6, characterized in that, before mixing the porous calcium silicate powder, the powder is previously subjected to granulation treatment to increase the diameter. Method.