Protective body for buried objects

Abstract

To provide a protector of an underground buried object, having light weight, nonetheless having high cutting resistance.SOLUTION: A protector of an underground buried object comprises: a plate-shaped member 11 having a surface 11a on one side in a thickness direction, and a rear surface 11b on the other side in the thickness direction; and a pair of L-shaped members 12 which are fixed to the rear surface 11b, extend in a first direction orthogonal to the thickness direction, and are arranged while separated from each other in a second direction orthogonal to the thickness direction and the first direction. In a cross-section vertical to the first direction, each of the L-shaped member 12 has a first flat plate portion 12a extending in the other side in the thickness direction from the rear surface 11b, and a second flat plate portion 12b extending to the outside of the plate-shaped member 11 in the second direction, from an end on the rear surface side of the first flat plate portion 12a. The plate-shaped member 11 is composed of a metal material having a Brinell hardness of 100 or less, the L-shaped member 12 is formed of a metal material having a Brinell hardness more than 100.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a protector for underground buried objects. [Background technology]

[0002] In recent years, there has been an increasing demand for the removal of utility poles at low cost. As a result, electric wires and other objects have begun to be buried shallow underground. On the other hand, to prevent accidents in which electric wires and other objects buried underground (hereinafter also referred to as "underground buried objects") are cut or damaged by pavement cutting work associated with subsequent road construction, it is common to cover and protect the underground buried objects with steel plates or the like.

[0003] For example, Patent Document 1 discloses a metal material for preventing cut damage, which has excellent cut protection properties and is attached to or disposed outside underground buried objects in order to prevent cut damage to underground buried objects accompanying road cutting work in road construction, etc. Patent Document 2 discloses a protective body that can reliably protect underground buried objects when cutting a road surface. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-338036 [Patent Document 2] Japanese Patent Application Publication No. 10-9480 Summary of the Invention [Problem to be solved by the invention]

[0005] The cutting damage prevention material described in Patent Document 1 exhibits high cutting damage prevention performance because it uses a metal material with a Brinell hardness of 100 or less. However, as a result of research by the present inventors, it was found that there is room for further improvement in cut resistance.

[0006] In addition, in the protector for underground buried objects described in Patent Document 2, for example, the surface of high hardness steel is covered with a material that deteriorates the cutter function, such as low hardness steel, to improve the cutting resistance. However, when low hardness steel and high hardness steel are stacked, an increase in weight is unavoidable, and there is a problem in that workability is deteriorated.

[0007] The present invention has been made to solve such problems, and has an object to provide a protector for underground buried objects that is lightweight yet has high cut resistance. [Means for solving the problem]

[0008] The present invention relates to a protector for an underground buried object as described below.

[0009] (1) a plate-like member having a surface on one side in a thickness direction and a back surface on the other side in the thickness direction; a pair of L-shaped members fixed to the back surface, extending in a first direction perpendicular to the thickness direction, and spaced apart from each other in a second direction perpendicular to the thickness direction and the first direction; In a cross section perpendicular to the first direction, each of the L-shaped members has a first flat plate portion extending from the back surface to the other side in the thickness direction, and a second flat plate portion extending from an end of the first flat plate portion on the back surface side toward an outside of the plate-shaped member in the second direction, The plate-shaped member is made of a metal material having a Brinell hardness of 100 or less, The L-shaped member is made of a metal material having a Brinell hardness of more than 100. A protective body for underground buried objects.

[0010] (2) The metal material constituting the plate-shaped member is steel, and the chemical composition of the steel is, in mass%, C: 0.10% or less, and Ceq defined by the following formula (i) is 0.10 or less; A protective body for underground buried objects as described in (1) above. Ceq=C+Mn / 6+Si / 24+Ni / 40+Cr / 5+Mo / 4+V / 14...(i) In the above formula, the element symbols represent the content (mass %) of each element.

[0011] (3) When viewed from the thickness direction, the plate-like member has a pair of linear edges extending in the first direction, a first end edge connecting one end of the pair of edges in the first direction, and a second end edge connecting the other end of the pair of edges in the first direction, At least one of the one end edge and the other end edge is curved in an arc shape. A protective body for underground buried objects as described in (1) or (2) above.

[0012] (4) When viewed from the thickness direction, The one end edge is curved in an arc shape so as to protrude outward, and the other end edge is parallel to the one end edge and curved in an arc shape so as to recess inward. A protective body for underground buried objects as described in (3) above. Effect of the Invention

[0013] According to the present invention, a protector for underground buried objects can be obtained which is lightweight yet has high cut resistance. [Brief description of the drawings]

[0014] [Figure 1] 1 is a perspective view of a protector for an underground buried object according to an embodiment of the present invention. [Diagram 2] 1 is a cross-sectional view perpendicular to a first direction of a protector for an underground buried object according to an embodiment of the present invention. [Diagram 3] 6 is a cross-sectional view perpendicular to the first direction of a protector for an underground buried object according to another embodiment of the present invention. FIG. [Figure 4] 10A and 10B are diagrams illustrating a state in which a protective body according to an embodiment of the present invention is cut. [Diagram 5] 13A to 13C are diagrams for explaining a method of joining an L-shaped member to a plate-shaped member. [Figure 6]1 is a view of a protector for an underground buried object according to an embodiment of the present invention as viewed from the thickness direction. [Figure 7] 13 is a view of a protection body for an underground buried object according to another embodiment of the present invention as viewed from the thickness direction. FIG. [Figure 8] 13 is a view of a protection body for an underground buried object according to another embodiment of the present invention as viewed from the thickness direction. FIG. [Figure 9] 1A to 1C are diagrams illustrating examples of construction of a protection body for an underground buried object according to one embodiment of the present invention and other embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A protector for an underground buried object according to one embodiment of the present invention will be described.

[0016] Fig. 1 is a perspective view of a protector for an underground buried object according to one embodiment of the present invention. The protector 10 includes a plate-shaped member 11 and a pair of L-shaped members 12. As shown in Fig. 1, in this specification, a direction perpendicular to the thickness direction of the plate-shaped member 11 is referred to as a first direction, and a direction perpendicular to the thickness direction and the first direction is referred to as a second direction.

[0017] Fig. 2 is a cross-sectional view perpendicular to a first direction of a protector for an underground buried object according to an embodiment of the present invention. As shown in Fig. 2, the protector 10 according to this embodiment is for protecting a buried object 20 buried in the ground so as to extend in a first direction.

[0018] The plate-like member 11 has a surface 11a on one side in the thickness direction (the upper side when buried, hereinafter also referred to as the "upper side") and a back surface 11b on the other side in the thickness direction (the lower side when buried, hereinafter also referred to as the "lower side"). That is, as shown in FIG. 2, the buried object 20 is buried on the back surface 11b side of the plate-like member 11.

[0019] 1 and 2, the pair of L-shaped members 12 are fixed to the back surface 11b of the plate-shaped member 11, extend in the first direction, and are spaced apart from each other in the second direction. The L-shaped member 12 has a first flat plate portion 12a and a second flat plate portion 12b. As shown in FIG. 2, in a cross section perpendicular to the first direction, the first flat plate portion 12a extends downward from the back surface 11b of the plate-shaped member 11. The second flat plate portion 12b extends from an end portion 12c on the back surface 11b side of the first flat plate portion 12a toward the outside of the plate-shaped member 11 in the second direction.

[0020] There is no particular restriction on the length of the second flat plate portion 12b in the second direction, and as shown in Figure 2, the outer end 12d of the plate-shaped member 11 in the second direction of the second flat plate portion 12b and the outer end 11c of the plate-shaped member 11 may be coincident in the second direction, or as shown in Figure 3, the end 11c of the plate-shaped member 11 may protrude outward beyond the end 12d of the second flat plate portion 12b.

[0021] Moreover, the plate-shaped member 11 is made of a metal material having a Brinell hardness of not more than 100. The type of the metal material is not particularly limited as long as it has a Brinell hardness of not more than 100, but for example, low carbon steel can be used.

[0022] Generally, the hardness of a steel material depends on the carbon equivalent. Therefore, the metal material constituting the plate-shaped member 11 is steel, and the chemical composition of the steel preferably contains, by mass%, 0.10% or less of C, and has a Ceq of 0.10 or less as defined by the following formula (i): Ceq=C+Mn / 6+Si / 24+Ni / 40+Cr / 5+Mo / 4+V / 14...(i) In the above formula, the element symbols represent the content (mass %) of each element.

[0023] C is an element that increases the hardness of a material and reduces its toughness, and is preferably kept as low as possible. Therefore, the C content is preferably 0.10% or less, and more preferably 0.05% or less. In addition, Ceq is the amount of the effect of other alloy elements on hardness converted into carbon, and like C, it is preferably kept as low as possible. Therefore, Ceq is preferably 0.10 or less, and more preferably 0.05 or less.

[0024] There is no particular limit to the thickness of the plate-like member 11, but if it is too thin, the cut resistance may be insufficient, while if it is too thick, it is difficult to reduce the weight. Therefore, the thickness of the plate-like member 11 is preferably 6 to 25 mm, more preferably 9 to 22 mm, and further preferably 12 to 19 mm.

[0025] In the case of producing the above-mentioned low carbon steel material, the production method is not particularly limited, but for example, it can be produced by subjecting a steel ingot or slab having the above-mentioned chemical composition to hot rolling. In order to keep the hardness of the steel material low, it is desirable that the heating temperature before hot rolling is 1100 to 1250°C, and the rolling finish temperature is 700°C or higher. In addition, the steel material may be used as it is after hot rolling, but it may be tempered after hot rolling. Furthermore, after hot rolling, normalization at 910°C or higher may be performed in order to remove residual strain introduced by hot rolling.

[0026] On the other hand, the L-shaped member 12 is made of a metal material having a Brinell hardness exceeding 100. There is no need to set an upper limit on the Brinell hardness of the metal material constituting the L-shaped member 12. However, if the hardness is increased excessively, it may become difficult to reduce costs. Therefore, it is preferable that the Brinell hardness of the metal material constituting the L-shaped member 12 is less than 300.

[0027] From the viewpoint of reducing costs, it is preferable to adopt, as a metal material having the above-mentioned hardness, for example, SS400, which is a general structural rolled steel material defined in JIS G 3101:2015.

[0028] There is no particular limit to the thickness of the L-shaped member 12, but if it is too thin, the cut resistance may be insufficient, while if it is too thick, it is difficult to reduce the weight. Therefore, the thickness of the L-shaped member 12 is preferably 3 to 15 mm, and more preferably 4 to 8 mm.

[0029] The protector 10 according to the present invention has the above-mentioned configuration and has high cut resistance even though it is lightweight. The reason for this will be explained. Fig. 4 is a schematic diagram showing a state when the protector according to one embodiment of the present invention is cut.

[0030] First, because the plate-shaped member 11 is made of a metal material with a Brinell hardness of 100 or less, the cut metal material adheres to the diamond on the cutting edge of the cutter used in pavement cutting operations, degrading the functionality of the cutter.

[0031] In addition, by having the L-shaped member 12 extending downward from the plate-shaped member 11, the cutting resistance is further improved. As shown in FIG. 4, the blade 30, whose cutting ability has deteriorated due to cutting the relatively soft plate-shaped member 11, attempts to cut the relatively hard L-shaped member 12 after passing through the plate-shaped member 11. As a result of closely observing the cut trace of the L-shaped member 12, the inventors found that the width of the cut trace of the L-shaped member 12 is larger than the width of the cut trace of the plate-shaped member 11. In other words, it is presumed that the cutting ability has deteriorated significantly due to a slight distortion occurring in the rotation of the blade 30.

[0032] Here, when fixing the L-shaped member 12 to the plate-shaped member 11, they are joined by providing welded parts 13a and 13b as shown in Fig. 5(a). However, in consideration of the workability during welding, it is common to fix the L-shaped member 12' to the plate-shaped member 11' in the orientation shown in Fig. 5(b).

[0033] 5(b), the blade 30, whose cutting ability has deteriorated due to cutting the plate-shaped member 11', immediately cuts the second flat plate portion 12'b of the L-shaped member 12' without bending. As a result, it is believed that the cutting ability of the blade 30 is restored by cutting the hard L-shaped member 12', and the blade 30 cuts the first flat plate portion 12'a in a straight line.

[0034] In contrast, in the protector 10 according to the present invention, the second flat plate portion 12b extends outward from the plate-like member 11, so the first flat plate portion 12a is cut directly by the blade 30, whose cutting ability has deteriorated as a result of cutting the plate-like member 11. It is presumed that this causes the blade 30 to become distorted when it enters the hard first flat plate portion 12a, resulting in a significant deterioration in its cutting ability.

[0035] Fig. 6 is a view from the thickness direction of a protector for an underground buried object according to one embodiment of the present invention, and Figs. 7 and 8 are views from the thickness direction of a protector for an underground buried object according to other embodiments of the present invention.

[0036] The shape of the plate-like member 11 as viewed in the thickness direction is not particularly limited, and may be, for example, rectangular. Also, the plate-like member 11 may have a shape as shown in Figs. 6 to 8. Specifically, when viewed in the thickness direction, the plate-like member 11 has a pair of linear edges 11d, 11e extending in a first direction, a first edge 11f connecting one ends of the pair of edges 11d, 11e in the first direction, and an other edge 11g connecting the other ends of the pair of edges 11d, 11e in the first direction.

[0037] In the shape shown in Fig. 6, only one edge 11f is curved in an arc shape so as to protrude outward. In the shape shown in Fig. 7, only the other edge 11g is curved in an arc shape so as to recess inward. Furthermore, in the shape shown in Fig. 8, one edge 11f is curved in an arc shape so as to protrude outward, and the other edge 11g is curved in an arc shape parallel to one edge 11f and recessed inward.

[0038] FIG. 9 is a diagram showing a typical example of construction of a protector for an underground buried object according to one embodiment (a) of the present invention and another embodiment (b).

[0039] When protecting a gently curved buried object, if the plate-like member 11 is rectangular, the protective body 10a is installed as shown in Fig. 9(a). In contrast, as shown in Fig. 9(b), by combining the protective body 10b with only one end edge 11f curved, the protective body 10c with only the other end edge 11g curved, and the protective body 10d with both the one end edge 11f and the other end edge 11g curved, the cutting edge of the cutting machine can be surely brought into contact with the L-shaped member during pavement cutting work, and the function of protecting the buried object can be exerted. In addition, it is possible to minimize the amount of material used, thereby reducing costs.

[0040] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. EXAMPLES

[0041] Two types of steels, A and B, were prepared, with the chemical composition and Brinell hardness shown in Table 1. Two types of protective bodies were prepared: a protective body consisting of only a plate-shaped member, and a protective body in which an L-shaped member was welded to the plate-shaped member. In each type of protective body, steels A and B were used for the plate-shaped member, and steel A was used for the L-shaped member.

[0042] [Table 1]

[0043] The plate-shaped member has a length of 300 mm in the first direction, a length of 200 mm in the second direction, and a thickness of 12 mm, and the L-shaped member is a 6 mm thick steel plate bent into an L shape, with a length of 40 mm in the first direction, a length of 50 mm below the first flat plate portion, and a length of 50 mm in the second direction of the second flat plate portion.

[0044] Each protective body was placed on a concrete surface with a groove of 50 mm width and 200 mm depth, and then subjected to a cutting test using a cutter equipped with a diamond blade. The cutting machine was moved in the second direction, and in the protective body equipped with an L-shaped member, cutting was performed from the side where the L-shaped member was fixed. Then, the time until all of the plate-shaped member having a length of 200 mm in the second direction was cut was measured. The cutting depth of the cutter was set to 100 mm from the concrete surface, and the set values ​​of the running speed of the cutter and the rotation speed of the diamond blade were constant.

[0045] The results are shown in Table 2.

[0046] [Table 2]

[0047] As is clear from Table 2, when a protective body satisfying the specifications of the present invention, which comprises a soft plate-shaped member and a hard L-shaped member, is used, the time required for cutting is significantly longer than when a protective body not satisfying the specifications, and cut resistance is significantly increased. [Industrial Applicability]

[0048] As described above, according to the present invention, a protector for underground buried objects which is lightweight yet has high cut resistance can be obtained. [Explanation of symbols]

[0049] 10 Protective Body 11 Plate-shaped member 11a surface 11b Back side 11c end 11d, 11e Pair of edges 11f One edge 11g Other edge 12 L-shaped member 12a 1st flat plate part 12b 2nd flat plate part 12c End of the first plate 12d End of second flat plate 13a, 13b Welded parts 20 Buried Objects 30 blades

Claims

1. A plate-like member having a surface on one side in a thickness direction and a back surface on the other side in the thickness direction; a pair of L-shaped members fixed to the rear surface, extending in a first direction perpendicular to the thickness direction, and spaced apart from each other in a second direction perpendicular to the thickness direction and the first direction; In a cross section perpendicular to the first direction, each of the L-shaped members has a first flat plate portion extending from the back surface to the other side in the thickness direction, and a second flat plate portion extending from an end of the first flat plate portion on the back surface side toward an outside of the plate-shaped member in the second direction, The plate-shaped member is made of a metal material having a Brinell hardness of 100 or less, The L-shaped member is made of a metal material having a Brinell hardness of more than 100. A protective body for underground buried objects.

2. The metal material constituting the plate-shaped member is steel, and the chemical composition of the steel is, in mass%, C: 0.10% or less, and Ceq defined by the following formula (i) is 0.10 or less; A protector for an underground buried object according to claim 1. Ceq=C+Mn / 6+Si / 24+Ni / 40+Cr / 5+Mo / 4+V / 14...(i) In the above formula, the element symbols represent the content (mass %) of each element.

3. When viewed from the thickness direction, the plate-like member has a pair of linear edges extending in the first direction, a first end edge connecting one end of the pair of edges in the first direction, and a second end edge connecting the other end of the pair of edges in the first direction, At least one of the one end edge and the other end edge is curved in an arc shape. A protector for an underground buried object according to claim 1 or 2.

4. When viewed from the thickness direction, The one end edge is curved in an arc shape so as to protrude outward, and the other end edge is parallel to the one end edge and curved in an arc shape so as to recess inward. The protector for an underground buried object according to claim 3.

5. The thickness of the plate-like member is 6 to 25 mm. A protector for an underground buried object according to any one of claims 1 to 4.

6. The thickness of the L-shaped member is 3 to 15 mm. A protector for an underground buried object according to any one of claims 1 to 5.

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