JP2005282753A - Underground embedded material cutting protecting member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting protecting member having improved cutting resistance for preventing the cutting of underground embedded material including information communication/distributing cables, pipes and structures in error during road surface cutting work for road construction. <P>SOLUTION: The cutting protecting member is formed of a ceramics sintered body or a metal-ceramics composite sintered body which has the ratio (Fn/Fns) of a nominal component to that of a standard sample is 0.9 or more when a value (Fn) of the nominal component of cutting resistance to be measured in plunge plane/UP CUT cutting work with a diamond blade is compared with the nominal component of cutting resistance of the standard sample formed of silicon nitride ceramics to be measured under the same cutting work conditions. Preferably, it is of a titanium diboride, silicon nitride, composite SiALON, or zirconia sintered body. It is arranged between the underground embedded material and a road surface or around the embedded material with front and rear end faces linked with each other along the direction of embedding the embedded material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cutting protection member for protecting underground buried objects such as information communication and distribution lines, piping, and structures from road accidents in road surface cutting work such as road construction.

  When embedding information communication / distribution cables, piping, structures, etc. in the ground, it is often necessary to embed near the road surface, such as where it intersects with other piping ducts. In such a case, a protective plate such as a steel plate is used as a protective member between the road surface portion and the buried object buried in the ground in order to prevent a cutting accident at the time of road surface cutting work performed later. It arrange | positions along the embedding direction of a buried thing. The road surface cutting operation is performed by an operator operating and moving a truck equipped with a concrete cutter, diamond blade, and the like. In a protective structure using a steel plate or the like, it is difficult to guarantee sufficient cutting protection against such road surface cutting work, and if the protective plate is cut, the buried object may be cut as it is. For this reason, the following devices have been devised as means for protecting against cutting underground objects.

a: A protective body in which hard granular materials (such as cast iron lump pieces) are dispersed and mixed in a soft base material (such as mortar) is placed between the road surface portion and the underground object. This means that when the cutter reaches the protector, the cutting operator is made aware of the presence of the protector by a sudden increase in cutting load, the occurrence of abnormal vibration, etc., and avoids the accident of cutting the buried object ( Patent Document 1).
b: A tile-shaped sintered member made of titanium diboride (TiB2) -based ceramics is embedded as a protective member in the upper portion of the embedded object. Due to the high diamond blade cut resistance (Vickers hardness ≧ 2400 kgf / mm ² ) of the protective member, the diamond blade is consumed to prevent the protective member from being cut and to protect the buried object (Patent Document 2).
c: The surface of a high-hardness steel plate coated with a low-hardness steel such as mild steel, a cutter function degrading agent such as resin, rubber, etc. is used as a protective body, and is disposed between the road surface portion and the buried object. When the cutter comes into contact with the protector, the cutter function-deteriorating material adheres to the cutting edge, so that the high-hardness steel plate is not cut and cutting of the embedded object is avoided (Patent Document 3).
d: As a cutting preventing material, a metal material having a Brinell hardness of 100 or less and having a higher cutting protection performance than an underground buried object is disposed. This is to reduce the hardness of the cutting prevention material and increase the stickiness, thereby improving the cutting resistance and preventing the cutting accident of the embedded object (Patent Document 4).
Japanese Patent Publication No. 05-009669 Japanese Patent Application Laid-Open No. 06-172042 JP 10-009480 A Japanese Patent No. 3105426

  The cutting ability of the cutting blade is greatly improved due to the increase in the horsepower of the cutting machine used for road surface cutting work and the technological advancement of diamond blades, making high speed and heavy cutting possible. There is a demand for further improvement and enhancement of the cutting prevention function for the protective member for protecting against cutting accidents. The present invention provides a cutting protection member having improved cutting resistance for coping with such road surface cutting work and capable of effectively avoiding accidents of cutting underground objects.

The cutting damage protection member for underground objects of the present invention,
The normal force (Fn) of the grinding resistance measured in the grinding process of plunge surface grinding with a diamond blade is the normal part of the grinding resistance of a standard sample made of silicon nitride ceramics measured under the same grinding conditions. Compared with force (Fns), it consists of ceramic sintered body or metal-ceramic composite sintered body whose grinding resistance ratio Fn / Fns is 0.9 or more with respect to the standard sample of normal force above, They are connected to each other along the direction.

  The “standard sample” used as the evaluation standard for the grinding resistance ratio “Fn / Fns” is the silicon nitride ceramics normal pressure sintered body “SN-1”, which is a fine ceramics center standard standard product (chemical composition). For material properties, see the Examples section below).

  The cutting protection member having a grinding resistance ratio of Fn / Fns of 0.9 or more according to the present invention has its cutting function against the cutting action by a high-density diamond blade due to falling off of diamond abrasive grains on the blade blade surface and intense heat generation. Degraded rapidly and exhibits outstanding cutting resistance. In general, it is considered advantageous to increase the hardness as much as possible as a rule to increase the cutting resistance to the grindstone cutter, but that alone can ensure a high grinding resistance ratio and outstanding cutting resistance based on it. Can not. The grinding resistance ratio is assumed to be due to the mutual balance of hardness, fracture toughness value, Young's modulus, bending strength, and the like. In the embedded object cutting protection structure formed by attaching the cutting protection member of the present invention to an embedded object buried in the ground, when a grinding wheel such as a diamond blade comes into contact with the cutting protection member, cutting of the working surface of the grinding wheel is performed. Rapid deterioration of the function causes abnormalities such as strong impact, stopping of the cutting machine's engine, stopping of the cutting direction feed operation, or climbing on the surface of the protective member, so the road surface cutting worker ensures the existence of underground objects It can be easily recognized and accidents resulting from cuts and damage to buried objects can be prevented.

  The cutting protection member of the present invention has a high grinding resistance ratio of 0.9 or more than the grinding resistance ratio (Fn / Fns). The higher the grinding resistance ratio (Fn / Fns), the higher the cutting resistance. A more preferable grinding resistance ratio (Fn / Fns) is 1.0 or more. With respect to the cutting protection member of the present invention, the grinding resistance (see the example column below) measured by a horizontal axis surface grinding machine using a diamond blade as a grindstone under constant plunge grinding conditions is a converted value per unit width of the blade edge. And about 10 N / mm or more, more preferably 12 N / mm or more.

The cutting protection member of the present invention is formed as a sintered body made of ceramics or a composite material (cermet) of ceramics and metal.
Examples of ceramic materials include titanium diboride (TiB ₂ ), silicon nitride (Si ₃ N ₄ ), composite sialon (Si ₃ N ₄ —Y ₂ O—Al ₂ O ₃ ), zirconia (ZrO ₂ ), and the like. And a cemented carbide as the ceramic-metal composite material.

Titanium diboride ceramics is a typical hard-to-sinter material, but by adding appropriate amounts of nickel (Ni), tungsten carbide (WC) and chromium carbide (Cr ₃ C ₂ ) as sintering aid components. Sintering difficulties are eliminated. Preferably, Ni is 0.2 to 10 mass%, WC is 0.1 to 7 mass%,
And a powder mixture consisting of 0.3 to ₃₀ mass% of Cr ₃ C ₂ and the balance TiB ₂ is used. More preferably, the amount ratio of Ni / WC is adjusted to 0.5 to 7, Cr ₃ C ₂ / (Ni + WC): 1 to 6, and the total amount of the _three components (Cr ₃ C ₂ + Ni + WC): adjusted to 43 mass% or less. . Sintering is achieved by applying a pressureless sintering technique and holding the temperature at about 1600-1880 ° C. for an appropriate time (about 0.5-10 Hr). The atmosphere is preferably an Ar atmosphere in order to prevent decomposition and alteration of titanium diboride.

Silicon nitride ceramics are also a material having poor sinterability, but spinel (MgAl ₂ O ₄ ) and partially stabilized zirconia (2.5 mol%) are used as sintering aid components.
By blending an appropriate amount of Y ₂ O ₃ -containing ZrO ₂ ), sintering difficulties can be eliminated and atmospheric pressure sintering can be applied. A preferred composition consists of spinel 2-7 mass%, partially stabilized zirconia 2-7 mass%, balance Si ₃ N ₄ , and is achieved by holding this powder mixture at a temperature of 1720-1780 ° C. for an appropriate time (eg, 1 Hr). . In the sintering atmosphere, pressurized nitrogen gas (about 0.1 MPa) is applied to prevent decomposition and alteration of Si ₃ N ₄ .

The compound sialon is M _X (Si, Al) ₁₂ (O, N) ₁₆ [wherein M is one or more elements selected from Mg, Ca, Y or rare earth elements, and x is 0.1 to 0.6] It is a compound which has a chemical composition shown by these. A particularly preferred example is one having a composition in which M is Y and x is 0.2. The composite sialon sintered body requires silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), and an oxide represented by M ₂ O ₃ or MO [M is Mg, Ca, Y, or a rare earth element]. A powder mixture mixed at a ratio can be used as a raw material to produce an atmospheric sintered body. Sintering is achieved by maintaining a nitrogen gas pressurized atmosphere (about 0.1 MPa) and keeping the temperature at about 1720 to 1780 ° C. for an appropriate time in order to prevent thermal decomposition and alteration of Si ₃ N ₄ .

Zirconia (ZrO ₂ ) has a relatively good sintering reactivity and can be successfully achieved by atmospheric pressure sintering held at a temperature of about 1350-1450 ° C. for an appropriate time without the need for sintering aids. .

  In the manufacturing process of the ceramic sintered body (atmospheric pressure sintered body), prior to the sintering process, the powder mixture eliminates the uneven distribution due to the different specific gravity and particle size of each component, and the product sintered body becomes homogeneous. In order to ensure the property, granulated powder having an appropriate particle size (about 10-100 μm) may be obtained by granulation with a spray dryer (wet spray dryer) or the like. The granulated powder is formed into a green compact according to the shape of the cutting protection member to be manufactured by pressure molding (uniaxial press, extrusion molding, cold isostatic pressing, etc.), and then the ceramic grade By subjecting to normal pressure sintering at a predetermined atmosphere and temperature according to the above, a sintered product having physical properties desired for the cutting protection member can be obtained.

  On the other hand, cemented carbide, which is an example of a ceramic-metal composite sintered body (cermet), is a hard, high melting point carbide particle such as tungsten carbide (WC) or titanium carbide (TiC), and a binder such as cobalt (Co). As a specific example of the material suitable for the cutting protection member of the present invention, a known WC-Co alloy (WC88, Co12, mass%) used for high-speed cutting tools, wear-resistant tools, etc. WC-TiC-Co alloy (WC79, TiC6, Co15, mass%) and the like.

  The cutting protection member (1) of the present invention has a plate-like body (flat plate, curved plate, etc.), a saddle-like body, a cylindrical body (half-split type, integral type, etc.) according to the shape and form of the buried object. ) And other suitable shapes. 1A is a flat plate, FIG. 1B is a curved plate having a required curvature or curvature, FIG. 1C is a bowl, and FIG. 1D is a pair of semicircular arcs. And FIG. 4E shows an example of an integrally formed cylindrical body. The shape and size of the cutting protection member (1) is selected according to the embedding form of the target embedded object, but the wall thickness is about 5 mm or more in order to make the cutting protection function by high grinding resistance more effective. Is preferred.

  A large number of the cutting protection members (1) are arranged along the direction of burying the underground object, connecting the edges of each other. The connection end edges of the cutting protection member are provided with an uneven shape for stabilizing the mutual connection form, if desired. In FIG. 2, one side of each cutting protection member (1) is a convex arcuate edge (E1), and the other side connected to this is a concave arcuate edge (E2) corresponding to the convex arc. FIG. 3 shows an example in which a protrusion (E3) is formed on one edge, and a recess (E4) in which the protrusion is inserted on the other edge. FIG. 4 shows a saddle type on one edge. This is an example in which a step (E5) is formed with a bowl-shaped step (E6) obtained by inverting it on the other edge. If the connecting end edges are connected in an uneven shape in this way, even when the cutting edge of the cutting blade enters the gap of the connecting portion in the road surface cutting operation, the effect of the uneven shape is Advancement stops at the uneven position, and the cutting protection effect is enhanced. Although FIGS. 2 to 4 are examples of plate-like bodies, various rugged shapes can be designed within a range that does not hinder the manufacturing process even in the case of a bowl shape or a cylindrical shape.

The structure for preventing damage to underground buried objects according to the present invention provides the above-mentioned structure for preventing damage to cutting between the buried object buried in the lower ground of the road surface part and the road surface part or around the buried object. It is formed by arranging the front and rear end faces of each other along the embedding direction.
FIG. 5 shows an example in which a cutting protection structure is formed by using a flat plate-like member as the cutting protection member (1). A buried object (for example, a tube containing information / communication cables, power distribution cables, etc.) (10) is fixed in concrete (13) placed in the soil layer in the lower ground (11) of the road surface. It is buried in the state. The plate-shaped cutting protection member (1) is located directly above the buried object (10) and is connected to the embedding direction (longitudinal direction), and is integrally fixed to the upper part of the concrete (10) so as not to be displaced. Or a steel plate (5), and a road surface portion (14) made of an asphalt layer or the like is formed.

  FIG. 6 shows that a protection structure is formed by using a cylindrical body (the half-shaped mold in FIG. 1 (d) or the integral-molded cylindrical body in FIG. 1 (e)) as the cutting protection member (1). It is an example. The cylindrical cutting protection member (1) surrounding the tubular buried object (10) surrounds the buried object (10) along the longitudinal direction by connecting the front and rear end edges thereof. A filler (sand, inorganic particulate matter, etc.) (15) is filled between the embedded object (10) and the cutting protection member (1) surrounding it. The buried object (10) surrounded by the cutting protection member (1) is disposed in a groove (12) cut in the lower ground (11), covered with soil, and made of an asphalt layer or the like. A road surface portion (14) is formed.

  In the defense structure in which the cutting protection member (1) of the present invention is attached to the underground object (10) as described above, the blade blade edge is the cutting protection member during the road surface cutting operation by the road surface cutting machine equipped with a diamond blade or the like. When contacted with (1), due to the high cutting resistance of the protective member (1), clear abnormal states such as impact on the blade, stoppage of feed operation in the cutting work direction (engine stop), or climbing on the upper surface of the protective member Will occur. Therefore, the cutting protection member (1) of the present invention functions as a highly reliable sensor that informs the operator of the presence of the underground object (10). The operator can easily recognize the existence of the underground object (10), and the cutting damage accident of the embedded object is prevented in advance.

[A] Measurement of grinding resistance (normal component force) As shown in FIG. 7, a test piece (on a surface grinder table (21) via a piezoelectric tool electrometer (made by Kistler: 9257A type) (22) ( TP) is fixed, plunge grinding is performed with a diamond blade (# 400) (23), and the load applied in the normal direction is measured.
-Measurement conditions-
The specimen size is 50 x 18 x 8 (mm) and ground in a direction parallel to the longitudinal direction. Before the measurement, a dressing process (grinding amount 1000 mm ³ ) using mild steel as a dressing material was performed.
・ Grinding machine: Horizontal surface grinding machine (Okamoto Machine Tool Works: PSG-63EX type)
・ Whetstone used: SDC400N75B / 200D × 15T (manufactured by Noritake)
・ Processing conditions: Grinding wheel peripheral speed 1800m / min
Table feed speed 15m / min
Cutting depth 10μm / pass
・ Grinding method: Plunge grinding / UP CUT

Table 1 shows the material types of the test materials, and Table 2 shows the physical properties of each test material. In the right column of Table 2, the value obtained by converting the normal component force (Fn) of the grinding resistance measured in the above grinding process per unit width of the grinding wheel edge (N / mm) and the grinding resistance ratio Fn / Fns ( Fns indicates the grinding resistance of the standard sample SN-1. The composition and physical properties of the standard sample are as follows.
[Standard Material] (Fine Ceramics Center Standard Sintered Product “SN-1”)
Grinding resistance (Fns): 11.1N / mm
Chemical composition _{(mass%) Si 3 N 4} : 88.5 or more, Mg: 2.06%, Ce: 3.54
%, Sr: 0.74, Al: 0.015,
Fe: 0.013, Y: 0.025, TO: 5.17
Physical properties Density: 3.2g / cc, Hardness HV: 15GPa, Bending strength: 1072GPa, Young's modulus: 290GPa,
Fracture toughness value K _IC : 7.1MPa ・ m ^1/2 , coefficient of thermal expansion: 3.8 × 10 ^-9 / ℃, thermal conductivity: 39.1W / mK

  As shown in the right column of Table 2, the Fn / Fns value of No. 1 (titanium diboride sintered body I) has extremely high grinding resistance exceeding 1.1, and No. 2 (silicon nitride type) Each of the sintered body), No. 3 (composite sialon sintered body) and No. 4 (zirconia-based sintered body) has high grinding resistance according to the titanium diboride sintered body. On the other hand, No. 5 (silicon carbide-based sintered body) has a hardness and Young's modulus that are higher than those of No. 2 and No. 3 sintered bodies, but has a remarkably low grinding resistance. The sintered body) has the same hardness as the No.2 and No.3 sintered bodies, but has a remarkably low grinding resistance. Although No. 7 (silicon nitride-based sintered body II) is a ceramic material having the same composition as No. 2, grinding resistance remains at a lower level than No. 2. This is considered to be because the hardness, bending strength, fracture toughness value, etc. of the sintered body were low due to insufficient firing in the sintering process, and the characteristics as silicon nitride ceramics were not sufficiently developed.

[B] Cutting test with diamond blade cutting machine (1) Installation of specimen (material to be cut) Concrete (26) with a steel pipe (25) (pipe diameter 50φ) as shown in Fig. 8 (thickness 20cm) ) Place the sample material (100 x 100 x 7 mm) (1) on the top surface, and cover the steel plate (5) (thickness 16 mm) to prevent the displacement, and the asphalt layer (14) (thickness) Install 5cm).
(2) Cutting conditions and cutting machine: Robin NDC type 2 EY160 (1600cc, 35HP) [Fuji Heavy Industries, Ltd.]
・ Blade: SDC400N75B / 200D × 15T
・ Blade rotation speed: constant speed of 1600 / rpm (rotation speed during normal cutting)
-Cutting speed: A = 20 mm / sec. B = 10 mm / sec.-Cutting operation: Cutting is started at a right angle from the front angle so that the blade blade enters from a certain depth, and the cutting is completed or until the engine stops or rides up. .

[C] Evaluation of cutting resistance Table 3 shows the test results. The numbers in parentheses in the “Sample Material” column indicate the sample numbers in Table 1. Cutting protection material (No. 1 to No. 4) with high grinding resistance is cut by running the blade or stopping the engine only by slightly cutting the outer periphery as shown in tests a to d. Has outstanding cutting resistance that makes it impossible to continue. On the other hand, specimens No. 5 (test e), No. 6 (test f) and No. 7 (test g) with low grinding resistance were easily cut, and damage to the blade edge after the cutting test (diamond grinding) Occurrence of dropout and seizure of grains) is slight and has poor cutting resistance.

The cutting protection member according to the present invention is embedded in underground objects (information communication / distribution line, piping, structures, etc.), so that the presence of underground objects in road surface cutting work for road works. It functions as a highly reliable recognition sensor that recognizes the road, and is excellent in protection against accidents caused by cutting damage to underground objects. It also contributes to the efficiency of road cutting work.
The cutting protection member of the present invention is useful not only as a protective member for underground objects, but also as a member for protecting members and devices in various fields from cutting accidents.

It is a perspective view which shows the example of a shape of a cutting | disconnection protection member. It is a top view which shows the example of the uneven | corrugated shape of the connection edge of a cutting | disconnection protection member. It is a top view which shows the example of the uneven | corrugated shape of the connection edge of a cutting | disconnection protection member. It is a top view which shows the example of the uneven | corrugated shape of the connection edge of a cutting | disconnection protection member. It is sectional explanatory drawing which shows the example of the defense structure which embed | buried the cutting | disconnection defense member. It is sectional explanatory drawing which shows the example of the defense structure which embed | buried the cutting | disconnection defense member. It is front explanatory drawing which shows the grinding resistance measurement point. It is sectional explanatory drawing which shows the specimen arrangement | positioning aspect for a cutting resistance evaluation test.

Explanation of symbols

1: Cutting protection member
5: Steel plate 10: Underground object 11: Lower underground 12: Groove 13: Concrete 14: Road surface 15: Filler

Claims (5)

  Underground object cutting protection members that are connected to each other along the embedding direction of the underground object, and the normal component (Fn) of the grinding resistance measured by plunge surface grinding with a diamond blade, Compared to the normal component (Fns) of the grinding resistance of a standard sample made of silicon nitride ceramics measured under the same grinding conditions, the ratio of the normal component to the standard sample (Fn / Fns) is 0.9 or more A cutting protection member for a buried object made of a ceramic sintered body or a metal-ceramic composite sintered body. A powder mixture in which Ni: 0.2 to 10%, WC: 0.1 to 7%, and Cr ₃ C ₂ : 0.3 to 30% as a sintering aid is usually added to TiB ₂ powder as a sintering aid. The cutting protection member for underground objects according to claim 1, comprising a titanium diboride ceramic sintered body obtained by pressure sintering. A silicon nitride system obtained by normal-pressure sintering of a powder mixture containing Si ₃ N ₄ powder with mass percentage of MgAl ₂ O ₄ : 2 to 7% and ZrO ₂ : 2 to 7% as a sintering aid The cutting protection member for underground objects according to claim 1, comprising a ceramic sintered body. Atmospheric pressure sintering of a powder mixture in which Si ₃ N ₄ powder is mixed with AlN as a sintering aid and an oxide represented by M ₂ O ₃ or MO [M is Mg, Ca, Y or rare earth element] M _X (Si, Al) ₁₂ (O, N) _{16 wherein} M is one or more elements selected from Mg, Ca, Y or rare earth elements, and x is 0.1 to 0. The cutting protection member for underground objects according to claim 1, comprising a composite sialon sintered body having a composition represented by [6]. The cutting protection member for underground objects according to claim 1, comprising a zirconia ceramic sintered body obtained by normal-pressure sintering of ZrO ₂ powder.

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