JPH0332575A - Grinding wheel with blow hole and manufacture thereof - Google Patents

Abstract

PURPOSE:To unnecessitate dressing in use and avoid the exhaustion of a grinding wheel due to dressing by adding a binder such as liquid paraffin to heat resistant fine powder so as to form granules to be added to a grinding wheel structure and further performing mixing and pressure-baking. CONSTITUTION:Granules 5 formed of heat resistant fine powder are added to a kind of grinding wheel structure, and a desired-grinding wheel is obtained by further applying pressure-baking. In truing dressing in the grinding wheel finishing process, the granules 5 formed of heat resistant particles in the grinding wheel structure fall off successively from the surface so as to form blow holes (6).

Description

[Detailed Description of the Invention] [Industrial Application Fields] The porous grinding wheel according to the present invention can be used in civil engineering and construction related fields such as stone, concrete and asphalt, electronic related fields such as silicon and ferrite, or mechanical and metal material related fields. It is used for cutting and grinding.

[Prior Art] In recent years, superabrasive grinding wheels have come to be used for processing the various materials mentioned above, but in many cases, nonporous grinding wheels are used for either metal bond or resin bond.

[51! The problem that Ming is trying to solve] Since metal-bonded or resin-bonded superabrasive grinding wheels are manufactured by pressurizing and firing powder materials, it is generally difficult to create pores, which are one of the constituent elements of the grinding wheel. Most of the superabrasive grinding wheels widely used in the market are nonporous grinding wheels.

The problems with this non-porous grinding wheel are that it is difficult to remove chips because it has no pores, that the coolant does not penetrate into the machined part, and that friction between the workpiece and the bonding material tends to occur. As a result, machining efficiency cannot be improved due to grinding burn due to increased temperature at the machining point, increased grinding resistance due to clogging of the grinding wheel, decreased sharpness and life, occurrence of scratches and cracks, and problems with the quality of the workpiece. In addition, there were many cases in which clogging occurred during processing, forcing the work to be interrupted and dressing to be performed.

[Means for Solving the Problems] As a method for solving the above-mentioned problems, a method has been proposed in which pore-forming protrusions are planted in a mold and pores are formed by the protrusions. However, in these methods, many fine protrusions must be implanted in the mold, and because of the fine protrusions, Easily damaged during pressure firing.

Furthermore, in order to change the porosity, it is necessary to prepare various molds with different sizes and numbers of protrusions, which poses problems in terms of manufacturing technology and manufacturing costs. The same proposal also states that ``wood chips, fine charcoal, etc. may be dispersed and mixed in the binding material and burnt out during firing to form the desired pores,'' but the manufacturing method involves pressure firing. In many cases, the cavities formed by firing almost disappear due to the molding pressure and no longer play the role of pores.

The present study provides a new means that eliminates the above-mentioned drawbacks. That is, a heat-resistant fine powder is added in the form of granules to one of the components of the grinding wheel. However, pores are not formed during the pressurized and fired whetstone manufacturing process.

In the truing and dressing process of the whetstone finishing process, the granules made of heat-resistant fine particles are removed from the surface of the whetstone in order to form pores, and by selecting the size and amount of the granules, The object of the present invention is to provide a porous grinding wheel having a desired size of pores or porosity.

[Function] When manufacturing a metal bond or resin bond grinding wheel using a pressurizing or firing method, it is difficult to manufacture a porous grinding wheel by gas generation or combustion. This is because even if pores are temporarily created due to gas or combustion, they disappear due to the pressure applied during pressurization and firing. In this proposal, heat-resistant granules are used in the pressing and firing process to create a nonporous grinding wheel, but pores are naturally formed during use, resulting in a manufacturing method that effectively functions as a porous grinding wheel. The manufacturing process and manufacturing examples will be explained.

a) Production of granules that act as pores The raw material for granules is Al + lOs, which does not burn during pressure firing.
, MgO, ZrO, Sea, StC, Si3N, etc. are used. Sea.

The case where fine powder is used will be explained as an example. The SeO□ fine powder was mixed with liquid paraffin and made into granules with a particle size of 0.3 w to 0.5 - by a known granule manufacturing method using a commercially available granulator. The particle size of the granules varies depending on the size of the superabrasive grains used, but as a rough guide, it is good to have approximately the same size to about 1/2 that of the superabrasive grains.

b) Manufacturing of whetstones A metal bond grinding wheel will be explained as an example.

Cobalt powder was selected as the binder, synthetic diamond of 40150 mesh was selected as the superabrasive, and alumina powder of 800 mesh was selected as the filler, and the above granules were added thereto and mixed. The volume mixing ratio in this example is 65% binder and 2% superabrasive.
5% filler, 2.5% filler, and 30% granules. These materials were sufficiently stirred and mixed using an ordinary mixer, filled into a mold, and molded into a grindstone chip using a hot molding press. The mixing ratio varies depending on the purpose of use or the material type of the workpiece, but if sharpness is important, the granule ratio should be increased and the grinding ratio (
When increasing the life span), reduce the granule ratio. The molding conditions are a temperature of approximately 900℃ and a pressure of approximately 3℃ in an inert gas atmosphere.
00 kgf/ln and the time was about 40 minutes. After molding, the chips were slowly cooled, taken out from the mold, and brazed with platinum to make a grindstone.

Instead of hot molding, the chip may be manufactured by cold molding or sintering in a furnace, but the chip strength will be somewhat lower. An example of a schematic diagram of the manufactured grindstone is shown in FIG. 1, and an example of a cross-sectional view of the chip is shown in FIG. The binder, abrasive grains, filler, and granules are uniformly dispersed in the chip, and pores have not yet been formed. The spaces that become pores are still dispersed in the form of granules, and there are no real spaces in the chip, so the compressive strength is higher than chips with spaces, and there is less elastic and plastic deformation due to pressure during processing.

FIG. 3 shows the pores formed on the surface of the chip when the chip was dressed or used. The granules dispersed in the chip are simply aggregates of fine powder as the liquid paraffin that holds the fine powder in a granular state decomposes and disappears during the heating process. Therefore, it tends to crumble and fall off during dressing or use. Furthermore, the drop-off pores become complete pores due to the cleaning action of the grinding fluid.

When a material with electrolubricity such as SeO□ is used as the fine powder for granules as in this example, the fallen fine particles also act as a lubricant, so the fine powder for granules is selected depending on the workpiece and purpose.

The formed pores can prevent clogging of chips and friction between the workpiece and the binding material. Furthermore, as shown in the figure, there are pore spaces, so the contact surface between the grinding wheel and the workpiece (grinding surface)
Cooling fluid (grinding fluid) can easily penetrate into the surface, prevent temperature rise at the grinding point, reduce temperature rise of machined parts, and prevent grinding burn and
High quality parts without cracks can be obtained. In addition, it is less likely to clog and the grinding resistance is low, so removal efficiency can be increased.

[Example] A granite surface grinding test was conducted on a one-pore grinding wheel manufactured by the method described in the previous section and a non-porous grinding wheel manufactured by a conventional method, and the removal efficiency was compared.

a) Grinding test conditions Processed product: Granite grindstone: 8 inches Segment type with and without holes, 45 mm x 2 CIM, 12 pieces, 450 rpm, 3.5 m/min Segment dimensions, number of pieces, grinding wheel Rotation speed... Grinding wheel feed rate... Grinding wheel pressing force... 60 kgf and 120 kgf Grinding time... 5 minutes Grinding fluid supply amount... 12 L/rnin b) Test results (removal amount) Perforated grinding wheel The grinding table during the test showed good sharpness with a low height, and the removal amount was about 163 times that of a conventional non-porous grindstone.

[Advantageous Effects] As described above, the advantages of a porous grindstone are a) b) No dressing is required during use, so the grindstone is not consumed by dressing, and wasted time due to dressing can be eliminated.

It is sharp and does not clog easily, so it has high removal efficiency.

C) The cooling liquid easily penetrates into the machined part, which lowers the grinding temperature and improves the quality of the machined parts.

However, the present invention provides a manufacturing method that can accurately control the size and distribution of pores that bring about this effect, and
This makes it possible to combine the effects of a lubricant.

[Brief explanation of drawings]

Fig. 1 Side cross-sectional drawing of a grinding wheel - base metal 2... grinding wheel tip Fig. 2 Cross-sectional view of the pressurized and fired chip 3... abrasive grains (diamond) 4... filler Binding material containing 5...
Granules Figure 3 Chip cross section showing pores formed during use 6 Pores formed due to shedding of granules

Claims (3)

[Claims] (1) In a grinding wheel obtained by mixing, pressurizing, and firing superabrasive grains, a binder, and a filler, granules obtained by adding a binder such as liquid paraffin to a heat-resistant fine powder are added and mixed;
A pressurized and fired porous grinding wheel. (2) In a method of manufacturing a grinding wheel by mixing, pressurizing, and firing superabrasive grains, a binder, and a filler, a binder such as liquid paraffin is added to a heat-resistant fine powder to form granules. A method for manufacturing a porous grinding wheel, characterized by adding and mixing, pressurizing, and firing. (3) A method for producing a porous grinding wheel according to claim 2, wherein a powder having lubricating properties is used as the heat-resistant fine powder.