JP2001277134A - Base metal for super abrasive grain wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base metal for a super abrasive grain wheel such that even if a sintering temperature for forming a layer of abrasive grains is 600 deg.C or higher, the abrasive grains can be secured to the base metal with high closeness by means of a metal bond composed chiefly of tin and copper, without cracking of the layer of abrasive grains. SOLUTION: The base metal 1 for the super abrasive grain wheel, having the layer of abrasive grains 2 secured to its outer peripheral edge by sintering while using as a binding agent the metal bond containing 20 to 45 wt.% tin and 55 to 80 wt.% copper is made of brass or a brass type alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base for a superabrasive wheel, and more particularly to a base for a superabrasive wheel using a metal bond mainly composed of tin and copper as a binder for abrasive grains. .

[0002]

2. Description of the Related Art Super-abrasive metal bond wheels for processing difficult-to-cut materials such as stone, concrete, ceramics, refractory bricks, cemented carbides, tool steels, etc. In addition, the basic structure is that which is fixed as an abrasive layer.

Conventionally, iron or an iron-based alloy having high strength and rigidity has been mainly used as a base metal, and an abrasive layer is formed by sintering a mixture of superabrasives and a metal bond. At the same time, it is bonded to the base metal surface.

[0004] This metal bond is generally a bond mainly composed of tin and copper. However, when the base metal is made of iron or an iron-based alloy, the adhesion of the abrasive layer to the base metal is reduced. There is a problem that a bonding failure is caused, or the abrasive layer cracks or peels off after sintering due to a difference in expansion and contraction between the abrasive layer and the base metal due to heat.

[0005] To solve the problem of poor bonding of the abrasive layer, copper plating is performed on the surface of the iron base metal. As a result, when the abrasive layer is formed by sintering on the surface of the base metal, the copper of the plating component and the copper in the metal bond are mutually diffused, and it is possible to make a stronger bond as compared with the case without copper plating. . In addition, for the problem of abrasive layer cracking and peeling due to the difference between expansion and contraction due to heat, the thermal expansion coefficient between the base metal and the abrasive layer is almost the same as the thermal expansion coefficient of the abrasive layer, and the strength is high. A method of interposing an intermediate layer has been adopted.

[0006] However, in order to interpose such an intermediate layer between the abrasive layer and the base metal, the intermediate layer and the abrasive layer are simultaneously formed with an up-pressing die and a down-pressing die. At the same time, a total of five dies are required for creating the outer peripheral surface of the abrasive layer, and two upward-pressing dies and two downward-pressing dies increase in comparison with the case where only the abrasive layer is formed. For this reason, not only does the cost of the mold increase, but also the number of steps increases, which greatly affects the product cost.

[0007] In response to such a problem, the applicant of the present invention has proposed 25
As a base of a superabrasive wheel for fixing an abrasive layer to the outer periphery of the base by sintering a metal bond containing の 50% by weight of tin, the linear expansion coefficient is 18 × 10 ⁻⁶ / ° C. to 25 × 10 ^-6 /
A base metal made of a bronze-based alloy having a composition ratio in the range of ° C. has been developed and disclosed in Japanese Patent Application Laid-Open No. 10-329036. By using such a base metal, the abrasive layer can be directly fixed to the base metal with high bonding force without applying copper plating to the base metal.

[0008]

However, the above-mentioned bronze alloy base metal is not versatile, and there is a limitation on the sintering temperature when the abrasive layer is fixed. A bronze-based alloy has a liquid phase when heated to about 700 ° C. or more, and has a strength lower than 600 ° C., and is easily deformed. Limited to metal bond wheels.

The metal bond requiring a sintering temperature higher than 600 ° C. is a bronze bond containing tin and copper as a main component and having a tin content of 45% by weight or less, and other metals such as silver, cobalt, and iron. , Nickel and the like. Conventionally, a superabrasive wheel using such a metal bond uses an iron-based base metal. However, since a metal bond of 20 to 45% by weight of tin has a large thermal expansion coefficient, it contracts with the iron-based base metal. Cracks are likely to occur due to the difference. As one of the measures for preventing cracking, there is a method of providing an intermediate layer as described above, but it has a problem in terms of cost due to an increase in the number of steps and mold cost.

The present invention provides a base for a superabrasive wheel which can be fixed to a base with high adhesion to a metal bond containing tin and copper as main components and which does not cause cracking of an abrasive layer. The purpose is to do.

[0011]

SUMMARY OF THE INVENTION According to the present invention, an abrasive layer can be fixed to a base metal with high adhesion even when the sintering temperature for forming the abrasive layer is 600 ° C. or higher, and In order to obtain a base metal that does not cause cracks in the grain layer, the base metal does not elute and deform at the sintering temperature, has a linear expansion coefficient similar to that of a metal bond, and The present invention has been completed based on the finding that it is necessary to use a base metal having a composition capable of obtaining a sufficient structure diffusion during sintering.

That is, in the base metal for a superabrasive wheel according to the present invention, an abrasive layer using a metal bond containing 20 to 45% by weight of tin and 55 to 80% by weight of copper as a binder is fixed to the outer peripheral edge by sintering. A base metal for a superabrasive wheel, characterized by being formed of brass or a brass-based alloy as a raw material.

Here, as the brass or brass alloy, one having a composition range that does not produce a liquid phase at a temperature of 900 ° C. or less can be used. 900 for brass
A composition range in which a liquid phase is not formed at a temperature of not more than ° C is a range where the zinc content is not more than 35% by weight. As shown in the known copper-zinc phase diagram, brass having a zinc content of 35% by weight or less is in the α phase at a temperature of 900 ° C. or less. In addition, zinc does not elute from the base during sintering. The lower limit of the zinc content is not particularly limited, but when the zinc content is less than 12% by weight, the linear expansion coefficient becomes less than 18 × 10 ⁻⁶ / ° C., and the linear expansion of the bronze-based metal bond is reduced. Since the difference from the coefficient becomes large, the lower limit of the zinc content is preferably set to 12% by weight. In addition, as a brass-based alloy that does not generate a liquid phase at a temperature of 900 ° C. or less, a trace amount of another metal capable of retaining an α phase at a temperature of 900 ° C. or less, for example, lead, tin, aluminum,
A brass alloy containing iron, nickel, or the like can be used.

The brass or brass alloy having the above composition range has a coefficient of linear expansion in the range of 18 × 10 ⁻⁶ / ° C. to 25 × 10 ⁻⁶ / ° C., so that 20 to 45% by weight of tin and 55 to 80% by weight of copper are used. %
Coefficient of linear expansion of metal bond containing 20 × 10 ^-6 / ℃ ～ 2
By using a base metal having a linear expansion coefficient close to 8 × 10 ⁻⁶ / ° C. and having a linear expansion coefficient in this range, cracking of the abrasive layer caused by a difference in thermal expansion coefficient during sintering does not occur. More preferably, the linear expansion coefficient of the base metal is at most about 5 times the linear expansion coefficient of the metal bond.
By setting the composition to be smaller than × 10 ⁻⁶ / ° C., it is possible to more reliably prevent the generation of cracks in the abrasive grain layer.

Further, since both the base metal made of brass and brass-based alloy and the bronze-based metal bond contain copper,
Copper is sufficiently diffused from the metal bond to the base during sintering, and the abrasive layer is firmly fixed to the base. Furthermore, there is an advantage that the base metal made of brass or a brass-based alloy has higher strength than the base metal made of bronze or a bronze-based alloy.

The metal bond for forming the abrasive layer in the superabrasive hole using the base metal according to the present invention is tin (20 to 45).
% By weight) and copper (55 to 80% by weight)
If necessary, silver, cobalt, iron, nickel or the like may be added. In the case of a bronze-based metal bond having a tin content of 20%, the sintering temperature for forming the abrasive layer is about 800 ° C. No cracks occur in the abrasive layer.

[0017]

Embodiments of the present invention will be described below based on test examples. [Test Example 1] As shown in FIG.
A super-abrasive grain wheel (invention 1) in which an annular diamond abrasive layer having a width of 3 mm and an inner diameter of 200 mm was joined to the outer periphery of a 0-mm base metal was manufactured.

The base metal 1 is brass containing 30% by weight of zinc and 70% by weight of copper, having a coefficient of linear expansion of 20 × 10 ⁻⁶ / ° C. and a hardness of HRB.
50, the tensile strength is 260 MPa. The abrasive layer 2
Using a diamond abrasive having a particle size of 140/170, the concentration is set to 100 and tin 2 is used as a binder.
A metal bond of 0% by weight and 80% by weight of copper was used. The linear expansion coefficient of the metal bond is 25 × 10 ⁻⁶ / ° C. In an electric furnace, sintering for forming an abrasive layer was performed at a sintering temperature of 750 ° C. and a pressure of 20 to 50 MPa.

As a comparative example, a super-abrasive wheel (comparative product 1) in which the same abrasive layer as that of the invention product 1 was formed on a bronze base metal of 15% by weight of tin and 85% by weight of copper, and an iron-made copper-plated iron A superabrasive wheel (Comparative Product 2) having the same abrasive layer as the invention was formed on a base metal. Further, tin 30 was placed on the same substrate as the superabrasive wheel of each of invention product 1, comparative product 1, and comparative product 2.
Super-abrasive wheels (invention product 2, comparative product 3, comparative product 4) in which an abrasive layer was formed at a sintering temperature of 550 ° C. using a metal bond of 70% by weight of copper and 70% by weight of copper were manufactured. Table 1 shows the manufacturing problems of each of these superabrasive wheels.

[0020]

[Table 1]

When the sintering temperature for forming the abrasive layer was 750 ° C., the wheels of the invention 1 of brass base metal and the comparison product 2 of iron base metal had no problem during sintering. However, the wheel of the comparative product 2 rusted on the base metal on the third day after production. In the wheel of the comparative product 1 of the bronze base metal, a part of the base metal was melted and deformed at the time of sintering, and thus could not be used as a product.

When the sintering temperature was 550 ° C., there was no problem in sintering between the invention product 1 of brass base metal and the comparative product 3 of bronze base metal. In Comparative Example 4 of iron base metal, a crack was generated in the abrasive grain layer due to a large difference in the coefficient of thermal expansion from the metal bond.

Test Example 2 A test piece shown in FIG. 2A was manufactured to investigate the bonding strength between an abrasive layer using a bronze-based metal bond and a base metal of various materials. The bending test was carried out by the method shown in (1). The test piece 3 is a strip-shaped piece having a thickness of 3 mm and a width of 7 mm, and the length of the base metal part 1a and the length of the abrasive grain layer part 2a are each 20 mm.
Is supported by two points with a span of 30 mm, and is subjected to three-point bending in which a punch 4 is pressed against the boundary between the base metal part 1a and the abrasive grain layer part 2a.

The material of the base portion 1a of the test piece 3 is the same as that of Test Example 1.
Brass, bronze, copper plating on iron, and four types of iron (test pieces 1 to 4), which are the same as the super-abrasive wheel of No. 1, and the metal bond of the abrasive layer portion 2a is a bronze-based bond of tin 20 / copper 80. . The sintering conditions for forming the abrasive layer are the same as in Test Example 1. Table 2 shows the test results.

[0025]

[Table 2]

The test piece 2 having a bronze base was partially melted and deformed at a sintering temperature of 750 ° C., and a bending test was impossible. In the test piece 4 having the iron base, the bonding strength of the abrasive layer portion was low, and the bonded portion was peeled off in the bending test. The iron test piece 3 in which the base metal part was plated with copper exhibited a high bonding strength, though not as good as the test piece 1 in which the base metal part was brass. However, cracking of the abrasive grain layer due to the difference in thermal expansion between iron and metal bond was observed. On the other hand, in the test piece 1 corresponding to the invention in Test Example 1, copper was sufficiently diffused between the metal bond and the base metal, and the test piece 1 did not peel off from the joint portion. It was broken from the near abrasive layer portion.

[0027]

According to the present invention, the following effects can be obtained.

900 ° C. as base metal for superabrasive wheel
By using a brass or brass-based alloy that does not produce a liquid phase at the following temperatures, using a base metal with a linear expansion coefficient close to that of the bronze-based metal bond that is the binder for the abrasive grains, It is possible to prevent the occurrence of cracks in the abrasive grain layer due to the difference in the coefficient of thermal expansion during sintering for forming the abrasive grain layer.

When a bronze-based metal bond is used, since both the base metal and the metal bond contain copper, the copper is sufficiently diffused from the metal bond to the base metal during sintering, and the abrasive grains are removed. The layer is firmly fixed to the base metal, and the removal of the abrasive layer is eliminated, thereby improving the safety.

[Brief description of the drawings]

FIG. 1 is a view showing a superabrasive wheel subjected to a test, wherein (a) is a front view and (b) is a longitudinal sectional view.

FIG. 2A is a perspective view showing a test piece, and FIG. 2B is an explanatory view of a test method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base metal 1a Base part 2 Abrasive layer 2a Abrasive layer 3 Test piece 4 Punch

Claims (3)

[Claims] 1. A base metal for a superabrasive wheel, wherein an abrasive layer using a metal bond containing 20 to 45% by weight of tin and 55 to 80% by weight of copper as a binder is fixed to an outer peripheral edge by sintering. A base for a superabrasive wheel, wherein the base is made of brass or a brass-based alloy. 2. The superabrasive wheel base according to claim 1, wherein the brass or the brass-based alloy has a composition range in which a liquid phase is not generated at a temperature of 900 ° C. or less. 3. The brass contains 12 to 35% by weight of zinc and 6% by weight of copper.
3. The superabrasive wheel base according to claim 2, which has a composition of 5 to 88% by weight.