JP2008073784A - cBN BRAZING GRINDING WHEEL - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cBN brazing grinding wheel which sufficiently secures ejecting quantity of abrasive grains, maintains sharpness favorable by keeping a dispersing state of the abrasive grains favorable, and is excellent in abrasive grain holding power. <P>SOLUTION: An element high in electronegativity, for example, chlorine 5 is attached on the circumference of the cBN abrasive grains 2. The cBN abrasive grains 2 with this chlorine 5 attached on them are fastened on a base metal by a wax material 3. Titanium 6 is contained in the wax material 3 in a range of more than 0.5 mass% and less than 5 mass%. A reactive layer 8 made of TiN is formed on a boundary part of the cBN abrasive grains 2 and a wax material layer 7 when the abrasive grains 2 are sintered in this state. A titanium ion existing as a positive ion in the wax material is attracted to the cBN abrasive grains 2 the surfaces of which are charged minus, density of the titanium ion is improved in the neighborhood of the boundary of the cBN abrasive grains 2 and the wax material layer 7, and the reactive layer 8 made of TiN is easily formed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cBN brazing grinding wheel in which cBN abrasive grains are fixed to a base metal by brazing.

  In the processing of automobile parts and the like, grinding wheels using diamond abrasive grains or cBN abrasive grains are used. Diamond abrasive grains are widely used as abrasive grains for grinding, but cBN abrasive grains are more suitable than diamond abrasive grains when grinding ferrous materials and composite materials thereof.

  Moreover, as a method for fixing the abrasive grains, there are metal bonding and brazing, and the fixing method is selected according to the application. In the metal bond wheel, it is difficult to increase the protrusion of the abrasive grains and to uniformly disperse the abrasive grains, and the grinding wheel by brazing is superior to the metal bond wheel in this respect.

From the above points, it is preferable to use a grinding wheel formed by brazing cBN abrasive grains in order to grind the iron-based material and its composite material with good sharpness. However, unlike brazing of diamond abrasive grains, when cBN abrasive grains are brazed, the abrasive grains and brazing material do not chemically react, and are merely physically fixed, so that the abrasive grain holding force is sufficient. I can't get it.
An example of a technique made for the purpose of increasing the abrasive grain holding power of a grindstone by brazing or metal bonding is described in Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4, and Patent Document 5.

Japanese Patent No. 3411233 Japanese Patent Laid-Open No. 10-264034 JP 2004-82276 A Japanese Patent Laid-Open No. 01-301070 JP 2006-130613 A

  In Patent Document 1, one or more layers of abrasive grains formed with surface recesses or through holes alone or in combination are disposed on a base metal, and the recesses or through holes of the abrasive grains are filled with a brazing material. Describes increasing the adhesive strength of abrasive grains without manipulating the components of the brazing material.

  Patent Document 2 describes that the retention of abrasive grains is enhanced by coating a binder containing an active powder component around the abrasive grains.

  Patent Document 3 includes a base metal and abrasive grains bonded to the base metal by a bond member mainly composed of a Cu-based alloy. The bond member is an alloy phase of Zr and Ti, a mixed phase, or an intermetallic material. A metal bond grinding tool is described that includes a compound to increase the abrasive retention.

  Patent Document 4 describes a diamond cutting and polishing tool in which diamond particles coated with a carbide-forming metal are brazed.

  Patent Document 5 includes a base metal, abrasive grains provided on the base metal, and a brazing material that holds the abrasive grains on the base metal. The brazing material includes an alloy containing copper and titanium, and vanadium. A grinding tool that suppresses the fogging of the brazing material to the top of the abrasive grain is described.

  Among these patent documents, the one described in Patent Document 1 increases the abrasive holding force by filling the brazing material, but even if this is applied when brazing cBN abrasive grains, it will be the abrasive grains. Since there is no chemical reaction with the material, physical sticking occurs.

  The thing described in patent document 2 causes the problem that the hardness of a cBN abrasive grain and the crushing value fall because a physical damage accompanies an abrasive grain. In addition, what is described in Patent Document 3 simply contains Ti in the bond. According to this structure, the adhering force is improved in terms of wettability between the cBN abrasive grains and the bond, but the wettability is improved too much so that the bond covers the entire abrasive grains, and the sharpness at the initial stage of grinding is lowered.

  The thing described in Patent Document 4 causes a problem that the bond covers the entire abrasive grains because the wettability is excessively improved as in Patent Document 3. In addition, what is described in Patent Document 5 is one of the methods for suppressing the covering of the abrasive grains by the bond, and by adding an additive to the brazing material, its fluidity is changed to cover the abrasive material. Is suppressed. However, in this method, since foreign substances enter the brazing material, the inherent reaction with Ti is hindered and the fixing force is reduced.

  The present invention has been made in consideration of such circumstances, and cBN brazing grinding which has a sufficient abrasive grain holding power while ensuring a sufficient amount of abrasive grain protrusion and maintaining a good dispersion state of the abrasive grains. The object is to provide a wheel.

  In order to solve the above-described problems, a cBN brazing grinding wheel of the present invention is a cBN brazing grinding wheel formed by brazing cBN abrasive grains to a base metal. The abrasive grains are fixed by a brazing material containing Ti, and a reaction layer made of TiN is formed at the boundary between the cBN abrasive grains and the brazing material layer.

  In the present invention, since an element having a high electronegativity is attached to the cBN abrasive grains, the cBN abrasive grains and the brazing material layer are simply compared with the case where the cBN abrasive grains are simply fixed using a brazing material containing Ti. It is easy to form a reaction layer made of TiN at the boundary between the two. Further, the brazing material does not cover the cBN abrasive grains on the top of the cBN abrasive grains as compared with the case where the cBN abrasive grains are coated with Ti in advance and brazed with the coated abrasive grains. Therefore, it is possible to increase the abrasive grain holding power while sufficiently securing the protruding amount of the abrasive grains, which is an advantage of brazing, and maintaining the sharpness of the abrasive grains in a well dispersed state.

  In this invention, the thickness of the said reaction layer is 2 micrometers or more and 20 micrometers or less, It is characterized by the above-mentioned.

  In order to braze the cBN abrasive grains to which elements having high electronegativity are attached, Ti in the brazing material is easily attracted to the cBN abrasive grains as compared with the case of simply brazing the cBN abrasive grains. Therefore, the concentration of titanium ions in the vicinity of the boundary between the cBN abrasive grains and the brazing filler metal layer increases, and a thick reaction layer made of TiN is formed. As a result, the thickness of the reaction layer becomes 2 μm or more and 20 μm or less.

When the thickness of the reaction layer is less than 2 μm, sufficient abrasive grain holding power cannot be obtained. On the other hand, when the thickness of the reaction layer exceeds 20 μm, the Ti diffusion becomes too wide and the chemical bonding force is dispersed. This is not preferable because the fixing force is weakened.
Any of Cl, Br, F, and I can be used as the element having a high electronegativity used here.

  In the present invention, the brazing material contains 0.5% by mass or more and 5% by mass or less of Ti.

  When the Ti content is less than 0.5% by mass, the reaction layer is not sufficiently formed, the reaction layer having a thickness of 2 μm or more cannot be formed, and sufficient abrasive grain retention is obtained. I can't. On the other hand, when the Ti content exceeds 5% by mass, the wettability of the brazing material is deteriorated, and it is necessary to increase the firing temperature in order to improve the wettability. As a result, since it becomes impossible to sinter in the sintering temperature range which does not cause the strength deterioration of diamond, it is not preferable.

  According to the present invention, to achieve a cBN brazing grinding wheel that has a sufficient abrasive grain holding force while ensuring a sufficient amount of abrasive grain protrusion, maintaining a good dispersion state of the abrasive grains, and maintaining a good sharpness. Can do.

Below, the cBN brazing grinding wheel of this invention is demonstrated based on the embodiment.
FIG. 1 shows an appearance of a cBN brazing grinding wheel according to an embodiment of the present invention, and FIG. 2 shows a fixed state of abrasive grains.
In FIG. 1, a cBN brazing grinding wheel 1 is formed by fixing cBN abrasive grains 2 to a cup-shaped base metal 4 with a brazing material 3.

  As shown in FIG. 2A, an element having a high electronegativity, for example, chlorine 5 is attached to the cBN abrasive grain 2 as shown in FIG. The cBN abrasive grains 2 to which the chlorine 5 is adhered are fixed by a brazing material 3 as shown in FIG. The brazing material 3 contains titanium 6 in a range of 0.5 mass% to 5 mass%. In addition to chlorine, Br, F, I, or the like can be used as an element having a high electronegativity attached to the cBN abrasive grains 2.

  When sintered in this state, a reaction layer 8 made of TiN is formed at the boundary between the cBN abrasive grains 2 and the brazing filler metal layer 7 as shown in FIG. Since an element having a high electronegativity is attached to the cBN abrasive grains 2, titanium ions present as cations in the brazing material 3 are attracted to the cBN abrasive grains 2 whose surface is negatively charged. Therefore, the concentration of titanium ions near the boundary between the cBN abrasive grains 2 and the brazing filler metal layer 7 is increased, and the reaction layer 8 made of TiN is easily formed. As a result, a relatively thick reaction layer 8 having a thickness of 2 μm or more and 20 μm or less is formed.

  The reaction layer 8 made of TiN can be formed at the boundary between the cBN abrasive grains 2 and the brazing filler metal layer 7 by coating the cBN abrasive grains 2 with Ti in advance and brazing the coated abrasive grains. However, it differs from the present invention in the following points. This will be described with reference to FIG.

  FIG. 3A shows a brazed Ti-coated abrasive. Since the wettability between the brazing material 3 and the coated Ti is good, the brazing material 3 passes through the Ti coating 10 by brazing. Thus, the surface of the cBN abrasive grains 2 is covered, and the portion that should normally protrude from the brazing material 3 is also covered with the brazing material 3. As a result, the sharpness of the edge of the surface of the cBN abrasive grain 2 does not function, and the sharpness is reduced. On the other hand, in the configuration of the present invention shown in FIG. 3B, the cBN abrasive grains 2 are not covered, so that a portion that should protrude from the brazing material 3 is not covered with the brazing material 3. Therefore, the sharpness is maintained well.

The cBN brazing grinding wheel having the structure described above can be manufactured by the following method.
The nickel sulfate plating solution used for electroplating contains nickel chloride, in which many nickel ions are present. The cBN abrasive grains 2 to be fixed are immersed in this solution for 3 hours or more. After the cBN abrasive grains 2 thus immersed are lightly washed with water, the cBN abrasive grains 2 are fixed to the base metal 4 with a brazing material 3 diluted with a binder and sintered at a temperature of 600 to 1000 ° C. in a reduced pressure atmosphere.

A test example is shown below.
A cup type wheel of φ200 ^D × 50 ^T × φ50 ^{H having} the shape shown in FIG. 1 was produced and subjected to a grinding test. FIG. 4 shows the result of testing the falling state of the abrasive grains in such a manner that the thickness of the reaction layer in the abrasive layer of the cup type wheel is different. The work material was a composite of aluminum and steel.

  When the thickness of the reaction layer was 2 μm or less, the abrasive grain dropout rate was high, whereas when the reaction layer thickness was 10 μm, no abrasive grain dropout was observed. Further, it has been difficult to form the reaction layer so that the thickness of the reaction layer is 20 μm or more. From the above test results, the thickness of the reaction layer is preferably 2 μm or more and 20 μm or less.

Next, the test results when the content of Ti in the brazing material is changed are shown in FIG.
In this test, a straight wheel of φ200 ^D × 50 ^w × 50.8 ^H using abrasive grains having a particle size of # 40/60 was used, and cast iron was used as a work material, 100 × 100 ports, and a cutting depth of 0. A 4 mm grinding test was performed. As shown in FIG. 5, when the Ti content in the brazing material is 0.2% by mass, the abrasive dropout rate is large, whereas when the Ti content in the brazing material is 3% by mass. The dropout rate of the abrasive grains is significantly reduced.

  The present invention is a grinding wheel for grinding an iron-based material or a composite material thereof. The grinding wheel ensures a sufficient amount of protruding abrasive grains, maintains a good dispersion state of the abrasive grains, and maintains a sharpness. It can be used as a cBN brazing grinding wheel with excellent grain retention.

It is a figure which shows the external appearance of the cBN brazing grinding wheel which concerns on embodiment of this invention. It is a figure which shows the adhering state of an abrasive grain. It is a figure for demonstrating the comparison with what brazed Ti covering abrasive grain. It is a figure which shows the result of having tested the fallen state of the abrasive grain as the thickness of the reaction layer differs. It is a figure which shows a test result when content of Ti in a brazing material is changed.

Explanation of symbols

1 cBN brazing grinding wheel 2 cBN abrasive grains 3 brazing material 4 base metal 5 chlorine 6 titanium 7 brazing material layer 8 reaction layer 10 Ti coating

Claims (4)

  In a cBN brazing grinding wheel formed by brazing cBN abrasive grains to a base metal, cBN abrasive grains to which an element having high electronegativity is adhered are fixed by a brazing material containing Ti, and cBN abrasive grains and brazing material A cBN brazing grinding wheel, wherein a reaction layer made of TiN is formed at a boundary with the layer.   The cBN brazing grinding wheel according to claim 1, wherein a thickness of the reaction layer is 2 μm or more and 20 μm or less.   3. The cBN brazing grinding wheel according to claim 1, wherein the element having a high electronegativity is any one of Cl, Br, F, and I.   The cBN brazing grinding wheel according to any one of claims 1 to 3, wherein the brazing material contains 0.5 mass% to 5 mass% of Ti.

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