Porous metal-bonded grinding wheel and method for manufacturing the same

Abstract

To provide a porous metal bond grindstone having a continuous hole formed inside, having a high porosity, and capable of suppressing clogging; and to provide a manufacturing method thereof.SOLUTION: In a porous metal bond grindstone 1 including multiple abrasive grains 3, and a metal porous body 2 which is a bond material for the abrasive grains, a long continuous hole 4 is formed by connecting multiple pores formed by removing multiple spacers, in the metal porous body 2, and the porosity is 40%-60%.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a porous metal bond grinding wheel and a method for manufacturing the same, and uses a metal porous body having continuously formed through-holes and a high porosity as a bond material for bonding abrasive grains. The present invention relates to a porous metal bond grinding wheel and a method for manufacturing the same.

Background Art

[0002] Carbon fiber reinforced resin (CFRP) characterized by being lightweight and highly rigid is widely used as a material in fields such as automobiles, medical, and aerospace. For products formed by CFRP, after laminating and molding CFRP plates, removal of surplus parts (trimming) is essential. Since this CFRP has to process hard carbon fibers, it is known as a material with severe tool wear. As a grinding wheel having high resistance to such tool wear, a diamond grinding wheel having a large number of cutting edges and being resistant to tool wear is known.

[0003] However, when using a diamond grinding wheel for CFRP processing, it is known that CFRP chips are likely to accumulate between a large number of cutting edges, and particularly in dry CFRP processing, it easily clogs. That is, CFRP has a problem that the resin layer connecting carbon fibers melts due to processing heat, clogging the diamond grinding wheel.

[0004] As a method for solving such clogging, a method has been proposed in which pores are formed in the grinding wheel to promote the self-cleaning action of the grinding wheel and suppress clogging. For example, Patent Document 1 discloses a method in which a substance (spacer) soluble in a solvent and having a melting point of 500°C or higher and super abrasive grains are mixed into metal bond powder, the mixture is sintered by hot pressing, and then the sintered body is immersed in a solvent to remove the substance (spacer) and form pores in the sintered body.

[0005] Also, as a porous metal material other than a grinding stone, Patent Document 2 discloses, for example, a method of forming an inorganic compound such as sodium nitrite into a predetermined shape, sintering it, then press-fitting molten metal into the pores of the sintered body, allowing it to solidify, and then treating it with a solvent to elute the inorganic compound to form a porous metal having pores with a three-dimensional network structure.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] By the way, in the metal-bonded grinding stone disclosed in Patent Document 1, although pores are formed in the sintered body, since the pores do not connect and are dispersed as independent pores, air (air) or cutting oil does not flow inside the metal-bonded grinding stone. Therefore, there is a problem that good discharge of chips cannot be performed and clogging cannot be suppressed. In addition, since the pores formed in the sintered body are independent pores, when NaCl is used as the spacer, there is a risk that NaCl remains in the sintered body. In that case, since the grinding stone oxidizes significantly, there is a problem that it is difficult to store.

[0008] The present inventors have intensively studied a grinding stone that can be suitably ground with clogging suppressed even in materials such as CFRP where the cutting edge wears out severely. In this study, the method disclosed in Patent Document 2 was also examined, but there were problems that the number of steps was large and each step required time, resulting in high manufacturing costs. In addition, since, for example, sodium nitrite used to form the spacer is a harmful substance, there is a problem of a large environmental load. To solve this problem, we discovered that clogging could be suppressed by using a metal bonded grinding wheel with excellent thermal conductivity, making the metal bond porous (formed with interconnected pores), and supplying a fluid such as air to the surface of the grinding wheel from inside, which led to the completion of this invention.

[0009] The present invention has been made under the circumstances described above, and aims to provide a porous metal bonded grinding wheel that has interconnected pores formed inside, has a high porosity, and can suppress clogging, as well as a method for manufacturing the same. [Means for solving the problem]

[0010] The porous metal bond grinding wheel according to the present invention, which has been made to solve the above problems, is made by bonding a plurality of spherical metal particles by sintering, Formed by melting a plurality of spacers composed of water-soluble inorganic salts or organic salts This porous metal bond grinding wheel is characterized in that it comprises a metal porous body, which is a bond material for abrasive grains and has interconnected pores through which a fluid can flow, and a plurality of abrasive grains arranged in the metal porous body. The metal porous body has spherical metal particles made of Cu or a metal element with a melting point higher than Cu, or a Cu-based alloy element. In the metal porous body, the spherical metal particles are connected to each other at their contact points by sintering, and gaps exist as pores between adjacent spherical metal particles. Furthermore, the metal porous body does not have independent pores through which the fluid does not flow, and the pores are continuously connected so as to connect the inner and outer surfaces of the metal porous body, forming a plurality of long interconnected pores with a width of at most 1 mm. The porosity of the metal porous body is 40% to 60%, and the interconnected pores function as passages for fluids such as gases such as oxygen and nitrogen, or liquids such as cutting oil.

[0012] According to such a configuration, the metal porous body has through-holes formed such that pores are continuously connected therein, and since the porosity is 40% to 60%, clogging of the workpiece can be prevented by grinding while flowing air or the like inside the grinding wheel. Further, since a plurality of pores are connected in the metal porous body to form the through-holes, no spacer (such as NaCl) remains inside the grinding wheel, and oxidation of the grinding wheel can be prevented. Further, the metal porous body, which is the bonding material for abrasive grains, is formed by sintering a plurality of spherical metal particles made of Cu, a metal element having a melting point higher than that of Cu, or an alloy element based on Cu, whereby high thermal conductivity and high strength can be obtained. Further, since the porous body is a metal body having high thermal conductivity, it can have a great effect on the processing of plastics and heat-resistant metals that are greatly affected by heat.

[0013] Further, the method for manufacturing a porous metal bond grinding wheel according to the present invention, which is made to solve the above problems, is such that a plurality of spherical metal particles are connected by sintering, Formed by melting a plurality of spacers composed of water-soluble inorganic salts or organic salts A method for manufacturing the above porous metal bond grinding wheel, comprising: a metal porous body, which is a bonding material for abrasive grains, having through-holes through which a fluid flows; and a plurality of abrasive grains disposed in the metal porous body, A step of mixing a plurality of abrasive grains, a spacer made of a water-soluble inorganic salt or organic salt and having a particle size in the range of 75 μm or more and 300 μm or less, and a plurality of spherical metal particles made of a metal of Cu, a metal element having a melting point higher than that of Cu, or an alloy element based on Cu and having a particle size in the range of 75 μm or more and 300 μm or less to form a mixture; a step of sintering the mixture to form a first sintered body; and a step of removing the spacer from the first sintered body by melting, wherein in the step of forming the mixture, the addition amount of the spacer is 40 to 60 vol.%.

[0014] Incidentally, It is desirable that the spherical metal particles are formed to have the same particle size as the spacers. Also, After the step of removing the spacer from the first sintered body, the first sintered body is Re-heat treated to improve the strength from the first sintered bodyIt is desirable to further include a step of forming a second sintered body.

[0015] According to such a method, the porous metal bond grinding wheel can be obtained, and for example, by manufacturing through discharge sintering, the manufacturing process can be simplified, the speed can be increased, and the manufacturing cost can be reduced.

Advantages of the Invention

[0016] According to the present invention, it is possible to provide a porous metal bond grinding wheel in which pores communicating with each other are formed inside, which has a high porosity and can suppress clogging, and a method for manufacturing the same.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0018] Hereinafter, a porous metal bond grinding wheel according to the present invention and a method for manufacturing the same will be described. The porous metal bond grinding wheel according to the present invention is a grinding wheel in which gases such as oxygen and nitrogen or liquids such as cutting oil are continuously supplied to the inside thereof to cool the abrasive grains and the surface of the bond material (grinding wheel surface), and to perform grinding while discharging chips.

[0019] FIG. 1 is a cross-sectional view showing an enlarged part of the porous metal bond grinding wheel according to the present invention. As shown in FIG. 1, the porous metal bond grinding wheel 1 includes a metal porous body 2 in which a plurality of spherical metal particles are connected by sintering, a plurality of abrasive grains 3 (for example, diamond abrasive grains) disposed in the metal porous body 2, and a long through-hole 4 formed in the metal porous body 2. In the metal porous body 2, the through-hole 4 is formed by continuously connecting a plurality of pores, and the porosity of the porous metal bond grinding wheel 1 is 40% to 60%. This through-hole 4 functions as a passage for gases such as oxygen and nitrogen or liquids such as cutting oil.

[0020] The metal porous body 2 is made of Cu, a metal having a melting point higher than that of Cu, or an alloy formed based on them. Specifically, examples of the metal having a melting point higher than that of Cu include W, Fe, Ni, Co, Mo, etc. Also, an alloy of Cu and the metal having a melting point higher than that of Cu described above may be used. By using these metals, a grinding wheel 1 excellent in thermal conductivity can be obtained.

[0021] Since the plurality of spherical metal particles of the metal porous body 2 are connected by sintering at their contact points, they are evenly arranged except for the location where the long through-hole 4 is disposed, and gaps (not shown) are uniformly present as pores smaller than the through-hole 4 between adjacent spherical metal particles. Further, the through-hole 4 is formed so as to connect the inner peripheral surface and the outer peripheral surface of the metal porous body 2, and is formed to have a width of several tens of μm to 1 mm. Thereby, the fluidity of gases such as air or liquids such as cutting oil in the grinding wheel 1 can be remarkably improved.

[0022] When grinding a CFRP material using the porous metal bond grinding wheel 1, it is used in an apparatus configuration as shown in, for example, Fig. 2. In Fig. 2, the porous metal bond grinding wheel 1 is formed in an annular shape. For example, a rotating shaft 10 extending in the vertical direction is inserted into the center of the grinding wheel 1 and fixed around the rotating shaft 10. The rotating shaft 10 is formed in a tubular shape, and high-pressure air is caused to flow through the tube. In addition, a plurality of communication holes 10a are formed on the side surface of the tube. Air (air) flows through the communication holes 10a, and the air is configured to flow through the grinding wheel 1 from the center side of the porous metal bond grinding wheel 1 toward the outer diameter side.

[0023] The rotating shaft 10 is rotated at a predetermined speed (for example, 188 m / min), and the CFRP material 20 to be ground is brought into contact with the rotating porous metal bond grinding wheel 1, and grinding is performed. At this time, since high-pressure air (air with an input pressure of 0.5 MPa) mainly passes through the communication holes 4 of the porous metal bond grinding wheel 1 and is ejected outward (air flows from the inner peripheral surface to the outer peripheral surface of the grinding wheel 1 and is ejected outward from the outer peripheral surface), grinding can be performed without clogging of the chips of the CFRP material 20. In addition, the abrasive grains 3 and the porous metal body 2 are cooled by the air (air) passing through the communication holes 4, and the adverse effect of the heat of the grinding wheel on the CFRP material 20 is suppressed. Note that depending on the object to be ground, a cutting oil other than air (air) can also be used.

[0024] Subsequently, a method for manufacturing the porous metal bond grinding wheel 1 will be described. First, as shown in Fig. 3, spherical metal particles 11 made of Cu, or a metal element having a melting point higher than that of Cu, or an alloy element of Cu and those metal elements, an inorganic salt spacer 12, and abrasive grains 3 made of, for example, Cu-Ni coated diamond are mixed and molded (formation of a mixture). As the inorganic salt, for example, NaCl, KCl, etc. can be used. In particular, as the spacer 12, it is preferable to use NaCl because it is easily melted in water at room temperature or the like. Furthermore, although the melting points of the NaCl and KCl are lower than those of the spherical metal particles 11 made of Cu or the like, by using the electric current sintering method in the subsequent sintering process, sintering can be achieved at a temperature lower than the sintering temperature in the ordinary hot pressing method or the like. Therefore, it is less likely to be adversely affected by the low melting point of the spacer 12.

[0025] Here, the present invention is characterized in that the particles of the spacer 12 are easily continuously arranged in the mixture to form the communication holes 4. In order to continuously arrange the spacers 12, the spacers 12 having a particle size in the range of 75 μm or more and 300 μm or less are used in a blending amount of 40 vol% or more and 60 vol% or less, and by mixing, as shown in FIG. 3, the spacers 12 can be easily continuously arranged.

[0026] Further, the spherical metal particles 11 which are the bonding material are formed to have the same particle size as the spacer 12 (it is desirable that the particle size is uniform). This is because when the particle size of the spacer 12 is larger than the diameter of the spherical metal particles 11, the spacer 12 forms large holes in the sintered body after sintering, and it is difficult to obtain a uniform flow path. On the contrary, when the particle size of the spacer 12 is smaller than the diameter of the spherical metal particles 11, the spacer 12 may surround the spherical metal particles 11 and prevent sintering. Also, the addition amount of diamond which is the abrasive grain 3 is, for example, 12.5 vol.%, and the addition amount of the spacer 12 is preferably 40 vol% or more and 60 vol% or less.

[0027] Next, the mixture is formed into a predetermined shape. Then, with respect to this formed body, using a plasma discharge sintering apparatus, the pressure inside the furnace is set to 10.2 MPa in a vacuum state, and it is pre-sintered at 650 ° C for 15 minutes. As a result, the formed body becomes a pre-sintered body (first sintered body). The pre-sintered body is immersed in distilled water to remove (desalt) the spacer 12 (NaCl), and the communication holes 4 are formed as shown in FIG. 4. Finally, without applying pressure in a vacuum state, sintering is performed at 750 °C or 820 °C for 2 hours to obtain the porous metal bond grinding wheel 1 (second sintered body). By such heat treatment again, the strength is improved.

[0028] In addition, although the strength of the grinding wheel increases due to this main sintering, it is also possible to adjust the grinding wheel strength (bond material strength) according to the grinding target. That is, in grinding, it may be necessary to reduce the strength of the bond material and promote the self-generation of cutting edges to improve the sharpness and suppress damage to the workpiece. Therefore, in the above manufacturing process, the sintering time and heating temperature can be adjusted to deliberately lower the strength of the porous metal bond grinding wheel 1 (second sintered body).

[0029] As described above, according to the present embodiment, since the long through holes 4 are formed in the metal porous body 2 and the porosity is 40% to 60%, it is possible to prevent clogging of the workpiece by grinding while flowing air or the like inside the grinding wheel. Further, since a plurality of pores are connected in the metal porous body 2 to form the through holes 4, the spacer 12 (such as NaCl) does not remain inside the grinding wheel, and oxidation of the grinding wheel can be prevented. In addition, the metal porous body 2 which is the bond material of the abrasive grains 3 is obtained by sintering a plurality of spherical metal particles made of Cu, a metal element having a melting point higher than that of Cu, or an alloy element based on Cu, so that high thermal conductivity and high strength can be obtained. Furthermore, since the porous body 2 is a metal body having a high thermal conductivity, it can have a great effect on the processing of plastics and heat-resistant metals which are greatly affected by heat. In addition, by manufacturing by spark plasma sintering, the manufacturing process can be simplified, high speed can be realized, and the manufacturing cost can be reduced.

[0030] In the above embodiment, Cu, a metal element having a melting point higher than that of Cu, or an alloy element based on Cu was described as an example of the spherical metal particles 11. However, the present invention is not limited thereto. For example, as the spherical metal particles 11, Fe, Ni, Mo, W, Sn, and alloys thereof may be used. In the above embodiment, NaCl and the like were described as an example of the spacer. However, the present invention is not limited thereto, and a water-soluble crystal material such as KCl may be used. Further, as long as it is water-soluble, it is not limited to inorganic salts but may also be organic salts. Further, a salt having a long crystal shape, for example, a needle-shaped crystal, may be used as the spacer.

Example

[0031] The porous metal bond grinding wheel and its manufacturing method according to the present invention will be further described based on examples.

[0032] (Experiment 1) In this Experiment 1, a porous metal bond grinding wheel was manufactured according to the present embodiment. Specifically, bronze (Cu-10Sn: Sn was blended at 10 wt% with respect to the base metal Cu) was used for the spherical metal particles, NaCl was used for the spacer, and diamond abrasive grains were used to produce a porous metal bond grinding wheel, and its performance was evaluated.

[0033] (Example 1) In Example 1, bronze (Cu-10Sn) was mixed at a ratio of 25.2 vol%, NaCl was mixed at 40 vol% for the spacer, and diamond abrasive grains were mixed at 34.8 vol% to form a compact. The metal particle diameter of the bronze was in the range of 75 μm or more and 125 μm or less, and the particle diameter of the spacer was the same as the metal particle diameter. Thereafter, with the green compact sintering temperature at 650 °C and the full sintering temperature at 750 °C, a porous metal bond grinding wheel having a porosity of 40% and an abrasive grain concentration of 100 was produced. The porosity of the produced grinding wheel was measured in accordance with "JIS R1634 (1998) Method for Measuring the Density and Open Porosity of Sintered Bodies of Fine Ceramics". The porous metal bond grinding wheel was formed in an annular shape, and in the apparatus schematically shown in Fig. 2, while flowing air at an input pressure of 0.5 MPa, the CFRP material was ground, and the normal grinding resistance (N) with respect to the grinding distance (mm) was measured. The results are shown in Fig. 5.

[0034] In Example 2, bronze (Cu-10Sn), NaCl, and diamond abrasive grains were mixed at the same mixing ratio as in Example 1 to form a compact. The metal particle diameter of the bronze was in the range of 75 μm or more and 125 μm or less, and the particle diameter of the spacer was the same as the metal particle diameter. Thereafter, with the green compact having a pre-sintering temperature of 650 °C and a sintering temperature of 750 °C, a porous metal bond grinding wheel with a porosity of 40% and an abrasive grain concentration of 100 was produced. In the apparatus schematically shown in Fig. 2, without flowing air inside, the CFRP material was ground, and the normal grinding resistance (N) with respect to the grinding distance (mm) was measured. The results are shown in Fig. 5.

[0035] In Example 3, bronze (Cu-10Sn) was mixed at a ratio of 42.6 vol%, NaCl as the spacer at 40 vol%, and diamond abrasive grains at 17.4 vol% to form a compact. The metal particle diameter of the bronze was in the range of 75 μm or more and 125 μm or less, and the particle diameter of the spacer was the same as the metal particle diameter. Thereafter, with the green compact having a pre-sintering temperature of 650 °C and a sintering temperature of 750 °C, a porous metal bond grinding wheel with a porosity of 40% and an abrasive grain concentration of 50 was produced. In the apparatus schematically shown in Fig. 2, while flowing air at an input pressure of 0.5 MPa, the CFRP material was ground, and the normal grinding resistance (N) with respect to the grinding distance (mm) was measured. The results are shown in Fig. 5.

[0036] In Example 4, bronze (Cu-10Sn) was mixed at a ratio of 22.6 vol%, NaCl as the spacer at 60 vol%, and diamond abrasive grains at 17.4 vol% to form a compact. The metal particle diameter of the bronze was in the range of 125 μm or more and 250 μm or less, and the particle diameter of the spacer was the same as the metal particle diameter. After that, a porous metal bond grinding wheel with a porosity of 60% and a grinding grain concentration of 50 was produced with the green compact sintering temperature at 650 °C and the full sintering temperature at 750 °C. In the apparatus schematically shown in Fig. 2, while flowing air at an input pressure of 0.5 MPa, a CFRP material was ground, and the normal grinding resistance (N) with respect to the grinding distance (mm) was measured. The results are shown in Fig. 5.

[0037] In Example 5, bronze (Cu-10Sn), NaCl, and diamond grinding grains were mixed at the same mixing ratio as in Example 4 to form a green compact. The metal particle diameter of the bronze was in the range of 125 μm or more and 250 μm or less, and the particle diameter of the spacer was the same as the metal particle diameter. After that, a porous metal bond grinding wheel with a porosity of 60% and a grinding grain concentration of 50 was produced with the green compact sintering temperature at 650 °C and the full sintering temperature at 820 °C. In the apparatus schematically shown in Fig. 2, while flowing air at an input pressure of 0.5 MPa, a CFRP material was ground, and the normal grinding resistance (N) with respect to the grinding distance (mm) was measured. The results are shown in Fig. 5.

[0038] The horizontal axis of the graph in Fig. 5 is the grinding distance (mm), and the vertical axis is the normal grinding resistance (N). As shown in Fig. 5, in Example 1, the normal grinding resistance was kept low up to a grinding distance of 400 mm, and the effect of air supply was observed. However, in Example 2, since air supply was not performed, clogging occurred from the beginning of processing, and the normal grinding resistance increased.

[0039] Also, in Example 3, since the grinding grain concentration was 50, the normal grinding resistance was kept low regardless of the grinding distance. Also, in Examples 4 and 5, since the porosity was as large as 60%, the normal grinding resistance was kept lower regardless of the grinding distance, and clogging could also be suppressed. From the above, it is recognized that the grinding wheel using the present invention has several times the life compared to the conventional non-porous grinding wheel.

[0040] (Experiment 2) In Experiment 2, a porous metal bond grinding wheel with a porosity of 60% was fabricated, and after performing CFRP grinding with the configuration shown in Fig. 2, the surface state was observed with an electron microscope. Specifically, for the porous metal bond grinding wheel shown in Fig. 6(a), bronze (Cu-10Sn) was mixed at a ratio of 22.6 vol%, NaCl was used as a spacer at 60 vol%, and diamond abrasive grains were used at 17.4 vol% to form a compact. Then, with the green compact sintering temperature set at 650°C and without performing full sintering, a porous metal bond grinding wheel with a porosity of 60% and an abrasive grain concentration of 50 was fabricated. On the other hand, for the porous metal bond grinding wheel shown in Fig. 6(b), bronze (Cu-10Sn) was mixed at a ratio of 22.6 vol%, NaCl was used as a spacer at 60 vol%, and diamond abrasive grains were used at 17.4 vol% to form a compact. Then, with the green compact sintering temperature set at 650°C and the full sintering temperature set at 750°C, a porous metal bond grinding wheel with a porosity of 60% and an abrasive grain concentration of 50 was fabricated.

[0041] Then, CFRP grinding was performed for each grinding wheel. The grinding conditions for the machining were as follows: a CFRP laminate with dimensions of 50 mm in length and width and 5 mm in thickness was used as the workpiece, the grinding wheel peripheral speed was 188 m / min, the feed rate was 200 mm / min, and the depth of cut was 0.5 mm. The number of machining passes was 20 passes. The results are shown in Fig. 6. Note that Fig. 6(a) shows a micrograph of the case without post-desalination re-sintering treatment, and Fig. 6(b) shows a micrograph of the case with post-desalination re-sintering treatment.

[0042] As shown in the photographs of Fig. 6, it was confirmed that none of the grinding wheels were clogged at all. Also, in Fig. 6(a), the shedding of abrasive grains and bond material was observed in places such as those surrounded by the dotted line. On the other hand, in Fig. 6(b), no shedding was observed, and an improvement in strength was confirmed. Note that in grinding, there may be cases where it is necessary to deliberately reduce the strength of the bond material and promote the self-generation of cutting edges to improve the sharpness and suppress damage to the machined workpiece. In the method for manufacturing a grinding wheel according to the present invention, since the strength of the bond material can be adjusted, grinding wheels for various applications can be manufactured.

Description of the reference numerals

[0043] 1 Porous metal bond grinding wheel 2 Porous body 3 Abrasive grains 4 Communication hole

Claims

1. A porous metal body which is a bonding material for abrasive grains, having communication holes through which a fluid formed by melting a plurality of spacers made of a water-soluble inorganic salt or organic salt flows, and a plurality of spherical metal particles are connected by sintering; and a porous metal bond grinding wheel comprising a plurality of abrasive grains disposed in the porous metal body, wherein the porous metal body is made of spherical metal particles made of Cu or a metal element having a melting point higher than that of Cu, or a metal of an alloy element based on Cu, in the porous metal body, a plurality of the spherical metal particles are connected to each other by sintering at their contact points, and gaps exist as pores between adjacent spherical metal particles, furthermore, the porous metal body has no independent holes through which the fluid does not flow, and a plurality of the pores are continuously connected so as to connect the inner peripheral surface and the outer peripheral surface of the porous metal body, and a plurality of long communication holes having a width of at most 1 mm are formed, and the porosity of the porous metal body is 40% to 60%, the porous metal bond grinding wheel, characterized in that the communication holes function as passages for fluids such as gases such as oxygen and nitrogen, or liquids such as cutting oil.

2. A method for manufacturing the porous metal bond grinding wheel according to claim 1, comprising a porous metal body which is a bonding material for abrasive grains, having communication holes through which a fluid formed by melting a plurality of spacers made of a water-soluble inorganic salt or organic salt flows, and a plurality of spherical metal particles are connected by sintering; and a plurality of abrasive grains disposed in the porous metal body, the method comprising: a step of mixing a plurality of abrasive grains, spacers made of a water-soluble inorganic salt or organic salt and having a particle size in the range of 75 μm or more and 300 μm or less, and a plurality of spherical metal particles made of Cu or a metal element having a melting point higher than that of Cu, or a metal of an alloy element based on Cu and having a particle size in the range of 75 μm or more and 300 μm or less to form a mixture; a step of sintering the mixture to form a first sintered body; a step of removing the spacers by melting them from the first sintered body; and comprising in the step of forming the mixture, the method for manufacturing a porous metal bond grinding wheel, characterized in that the addition amount of the spacers is 40 to 60 vol.%.

3. The method for manufacturing a porous metal bond grinding wheel according to claim 2, wherein the spherical metal particles are formed to have the same particle size as the spacers.

4. After the step of removing the spacer from the first sintered body, The method for manufacturing a porous metal bond grinding wheel according to claim 2, further comprising a step of heat-treating the first sintered body again to form a second sintered body having a higher strength than the first sintered body.

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