JPH0691544A - High speed cutting grinding wheel for steel pipe - Google Patents

Abstract

PURPOSE:To prevent seizure of a pipe end surface when a steel pipe, particularly, a high carbon steel pipe or a thick wall steel pipe is cut. CONSTITUTION:Both side surface side grinding wheel plates 1 and 1 where an abrasive grain diameter is large and a joining degree is strong, are superposed and joined integrally upon both side surfaces of inside grinding wheel plates 2 and 2 where an abrasive grain diameter is small and a joining degree is weak. When a steel pipe is cut by using such grinding wheel 3, seizure of a pipe end surface can be prevented, and unit requirement of the grinding wheel can be improved significantly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grindstone for cutting a steel pipe, and more particularly to a steel pipe high-speed cutting grindstone suitable for cutting a high carbon steel pipe or a thick steel pipe.

[0002]

2. Description of the Related Art As a method for cutting a steel pipe, a bite, a saw,
Grinding stones, press cutters, rotary risk cutters, gas cutting and the like can be mentioned, but grinding stones are mainly used for cutting small diameter pipes. When using a cutting wheel to cut a steel pipe, if a cutting wheel with a large abrasive grain size is used, the cutting wheel will be sharp and the heat release rate will be low, but the force applied to each abrasive particle is large. A work-affected layer such as a crack layer or a plastically deformed layer is formed on the cut surface. Further, in the case of a cutting stone for cutting fine abrasive grains, the force applied to each abrasive grain becomes small, so the plastic deformation layer is reduced, but the plastic strain of the chips is large, and moreover, it is processed with a large number of abrasive grains. Since the frictional force is large and a large amount of heat is generated and the temperature of the cut portion becomes high, the heat-affected layer becomes large. In addition, since the cut portion becomes hot, it is likely to be plastically deteriorated, and the work-affected layer becomes large.

As described above, whether the cutting grindstone having a large abrasive grain size or the cutting grindstone having a small abrasive grain size is used, the work deformation layer of the cut surface is large. In particular, in the cutting of high carbon steel pipes and thick steel pipes, there were problems such as pipe end surface seizure, oblique cutting, and deterioration of the basic unit of grindstone. For this reason, when cutting a high carbon steel pipe or a thick steel pipe, as a countermeasure against seizure of the pipe end surface, the grinding stone basic unit is ignored and a grinding stone one rank softer than the grinding stone for general steel is used for cutting.

Conventionally, in order to reduce the work-affected layer of the cut surface, the outer peripheral portion of a cutting grindstone having a relatively fine abrasive grain is partially cut to provide a slit so that the cooling liquid can easily flow to the cut portion. This has been dealt with by improving the cooling property and reducing the heat generation. Further, as a cutting grindstone for reducing the work-affected layer of the cut surface, a cutting grindstone (special feature: (Kaisho 60-6359)
Is proposed.

[0005]

In the method of reducing the heat generation by allowing the cooling liquid to easily flow to the cutting portion, an excessive force is applied to the working surface by the corner portion of the slit, and rather the work-affected layer due to plastic deformation is caused. Has the drawback of becoming large. Further, the cutting grindstone disclosed in Japanese Patent Laid-Open No. 60-6359 has a problem that it is difficult to withstand the impact particularly at high speed cutting, and if the circular deformation is not the same, oblique cutting of the cutting material and seizure of the pipe end surface occur. .

An object of the present invention is to provide a steel pipe high-speed cutting grindstone capable of preventing seizure of the end face of the pipe during cutting of a steel pipe, particularly a high carbon steel pipe or a thick-walled steel pipe, and improving the basic unit of the grindstone. .

[0007]

[Means for Solving the Problems] The inventors of the present invention have made extensive studies to achieve the above object. As a result, the sharpness of both sides of the grindstone is improved by superposing the grindstone plates with large grain size and strong bond on both sides of the grindstone plate with a small inner grain size and weak bond, and by combining them in a sandwich shape. However, the inventors have found that the shape of the grindstone itself can be secured and the occurrence of seizure can be suppressed on the inner side, and arrived at the present invention.

That is, according to the present invention, the grindstone plates on both side surfaces having a large abrasive grain size and a high degree of bonding are superposed on both side surfaces of the inner grindstone plate having a small abrasive grain size and a weak degree of bonding, and integrally bonded. A high-speed cutting stone for steel pipes.

[0009]

In the grindstone of the present invention, since the grindstone plates having a large abrasive grain size and a high degree of bonding are superposed on both sides of the inner grindstone plate having a small grain size and a weak degree of bonding, both sides of the grindstone are bonded. Since the surface is strong and hard, it has good sharpness, the shape of the grindstone itself is secured, the deformation of the grindstone which is considered to be the cause of seizure of the pipe end surface when cutting the steel pipe is prevented, the impact at the time of cutting can be mitigated, and the grindstone The basic unit is greatly improved. Also,
Since the inside of the grindstone sandwiched between the grindstone plates having a large abrasive grain size and a high degree of bonding has a small abrasive grain size and a weak degree of bonding, the plastic deformation layer is reduced and seizure is suppressed. Therefore, the grindstone of the present invention can prevent seizure of the end face, oblique cutting and deterioration of the basic unit of the grindstone when the conventional high carbon steel pipe or thick steel pipe is cut.

[0010]

【Example】

Embodiment 1 Details of the present invention will be described below with reference to FIGS. 1 to 3 showing an embodiment. FIG. 1 is a sectional view of a cutting grindstone of the present invention, FIG. 2 is a sectional view showing deformation of a conventional grindstone which is considered to be a cause of seizure, and FIG. 3 is a sectional view showing a shape after use of the cutting grindstone of the present invention. In FIG. 1, reference numerals 1 and 1 denote whetstone plates on both side surfaces having a large abrasive grain size and a high degree of bonding, 2 and 2 denote inner whetstone plates having a small grain size and a weak degree of bonding, and 3 denotes a whetstone plate 2 and 2. It is a cutting grindstone which is press-formed into a sandwich shape so as to be sandwiched between the grindstone plates 1 and 1 and integrally joined.

In the cutting wheel 3 having the above structure, when the steel pipe is cut, the inner grinding wheel plates 2 and 2 have a smaller abrasive grain size and a weaker degree of bonding than the grinding wheel plates 1 and 1 on both side surfaces, and therefore wear from the inside occurs. Because of the shape shown in Fig. 2, deformation of the conventional cutting grindstone shown in Fig. 2, which is considered to be the cause of seizure, can be prevented, and the impact generated when cutting a steel pipe can be mitigated. Moreover, since the shape shown in FIG. 3 continues stably, it can be used up to the minimum limit without being discarded in the middle, and the basic unit of the grindstone can be greatly improved.

Example 2 As the grindstone plates 1 and 1 on both sides, abrasive grains having a grain size of 30 were used as a binder with a resinoid bond, and the outer diameter was 1500 mm, the thickness was 3 mm, and the hole diameter was 203.2 mm. The inner grindstone plates 2 and 2 are used as inner grindstone plates 2 and 2, and abrasive grains having a grain size of 24 are used as a binder to bond them with a bond degree Q. The outer diameter is 1500 mm, the thickness is 3 mm, and the hole diameter is 203.2.
mm grindstone plates are bonded together by press work with glass fiber interposed between the grindstone plates, and the outer diameter is 1500 m.
m, thickness 12 mm, hole diameter 203.2 mm, three cutting grindstones A, B, and C were manufactured. For comparison, the grain size is 20
The abrasive grains of No. 1 are used as a binder with a resinoid bond and bonded at a bond degree R of an outer diameter of 1500 mm, a thickness of 3 mm, and a hole diameter of 2
Four 33.2 mm whetstone plates were joined by pressing with glass fibers interposed between the whetstone plates to produce a cutting whetstone D having an outer diameter of 1500 mm, a thickness of 12 mm, and a hole diameter of 203.2 mm.

Using each of the cutting wheels A to D, at a wheel peripheral speed of 4800 m / min, an outer diameter of 165.2 mm and a wall thickness of 3
Cutting a 0.0mm high carbon steel (S45C) seamless steel pipe, measuring the number of cuts before replacement, and setting a cutting ratio indicating a grinding stone basic unit of a cutting grindstone D of a comparative example to 1.0, and a cutting grindstone A The cutting ratio of C to C was determined. The result is shown in FIG. As shown in FIG. 4, the cutting ratios of the cutting wheels A to C of the present invention are significantly improved to 1.3 to 1.8, the average cutting ratio of 1.5, and the cutting surface is free from seizure of the pipe end surface. The quality was good.

[0014]

As described above, the cutting grindstone of the present invention can prevent seizure of the pipe end surface and can significantly improve the basic unit of the grindstone.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a cutting grindstone of the present invention.

FIG. 2 is a cross-sectional view showing a deformation of a conventional grindstone which is considered to be a cause of seizure.

FIG. 3 is a cross-sectional view showing a shape after using the cutting grindstone of the present invention.

FIG. 4 is a graph showing cutting ratios of cutting wheels A to D in Example 2.

[Explanation of symbols]

 1, 2 Whetstone plate 3 Cutting whetstone A, B, C, D Cutting whetstone

Claims (1)

[Claims] 1. A steel pipe high-speed cutting grindstone, characterized in that, on both sides of an inner grindstone plate having a small abrasive grain size and a weak bond, a grindstone plate having a large abrasive particle size and a strong bond is superposed and integrally bonded. .