Cutting method

Abstract

To provide a cutting method with higher work efficiency.SOLUTION: After a pair of first cutting grooves 1, 1 is formed, first annular cutting grooves 10 that have relatively large diameters are formed at each of the four corners of a cut piece portion CP so as to be respectively inscribed in the first cutting grooves 1 and the second cutting grooves 2, and second annular cutting grooves 20 that have relatively small diameters are formed so as to be respectively inscribed in the first cutting grooves 1 and the second cutting grooves 2, so that parts of the areas surrounded by the second annular cutting grooves 20 overlap with the areas surrounded by the first annular cutting grooves 10, and by chipping off the protruding part of the areas surrounded by the second annular cutting grooves 20 that do not overlap with the areas surrounded by the first annular cutting grooves 10, communicating recesses RT are formed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a cutting method that is primarily carried out when replacing an expansion joint. [Background technology]

[0002] In viaducts and bridges, gaps are provided between adjacent deck plates that make up the bridge girder, and between the deck plates and the supporting frames that support the ends of the deck plates, and expansion joints are installed in these gaps to ensure safety for traffic and to absorb expansion and contraction due to temperature of the deck plates, but expansion joints deteriorate over time and need to be replaced at appropriate intervals.To replace an expansion joint, the following cutting method has been proposed, in which the bottom of the band-shaped area containing the expansion joint is cut in a direction approximately parallel to the road surface, that is, in the so-called horizontal direction.

[0003] Fig. 10 is an explanatory diagram showing, in plan view, the horizontal cutting method disclosed in Patent Document 1, which will be described later, in which T is an expansion joint installed in the gap G of the viaduct. Fig. 11 is a partially cutaway perspective view showing the structure of the viaduct in the surrounding area, including the expansion joint T shown in Fig. 10. Note that in both figures, corresponding parts are assigned the same numbers.

[0004] As shown in Figures 10 and 11, a gap G is provided between adjacent floor slabs F, F, and one or more layers (two layers in Figure 11) of paving layers H, H are laminated on the top surface of each of the concrete floor slabs F, F. An expansion joint T is interposed within this gap G, and the expansion joint T is supported and fixed to the floor slabs F, F by anchor reinforcement (not shown) so that its top surface is approximately flush with the surface of the paving layer H. In order to replace an expansion joint T of this type, an appropriate area including the expansion joint T is cut into a strip shape at the required depth as follows.

[0005] That is, first cutting grooves 101, 101 parallel to the longitudinal direction of the expansion joint T are formed at the opposing ends of adjacent floor slabs F, F at positions spaced an appropriate distance from the expansion joint T, with a depth greater than the thickness of the expansion joint T. These first cutting grooves 101, 101 are formed, for example, by cutting the entire thickness of the pavement layers H, H and part of the thickness of the floor slabs F, F using a disc-shaped rotary blade of the required thickness. The width of the first cutting grooves 101, 101 is slightly greater than the width of the annular wire saw. Meanwhile, auxiliary grooves 107, 107 are provided inside both first cutting grooves 101, 101, parallel to the first cutting grooves 101, 101, to prevent problems such as jamming when cutting with a wire saw inserted into the first cutting grooves 101, 101.

[0006] Next, second cutting grooves 102, 102 having the same depth as the first cutting grooves 101, 101 are formed at positions between the first cutting grooves 101, 101 and at positions a predetermined distance inward from both ends, thereby forming a strip-shaped cut piece portion CP in a plan view. At this time, both ends of the first cutting grooves 101, 101 are extended to positions outside the second cutting grooves 102, 102, and these portions serve as so-called excess cuts 105, 105, 105, 105, which ensure the cutting dimension of the floorboards F, F in the depth direction by the rotating blade.

[0007] Next, a core drill is used to form annular cutting grooves 110, 110, 110, 110 that are annular in plan view at least at four corners of the cut piece portion CP, the annular cutting grooves 110 having the same depth as the first cutting grooves 101, 101 and communicating with the first cutting grooves 101 and second cutting grooves 102 that form the corresponding corners. At this time, the thickness of the core bit used in the core drill is slightly larger than the width of the wire saw.

[0008] Then, for example, a wire saw cutting machine main body that rotates a circular wire saw to cut the object is placed at approximately the center of the cut piece portion CP in the longitudinal direction, and the wire saw is pulled out from the wire saw cutting machine main body and inserted to the bottom of one of the second cutting grooves 102, the circular cutting grooves 110, 110 located at both ends thereof, and the first cutting grooves 101, 101 that communicate with both circular cutting grooves 110, 110. Then, while maintaining the depth position of the wire saw, the wire saw is rotated and pulled back toward the wire saw cutting machine main body parallel to the surfaces of the floor plates F, F, thereby cutting one end side of the cut piece portion CP into a strip shape at the required depth. A similar operation is performed on the other end side of the cut piece portion CP, thereby cutting the entire length of the cut piece portion CP to the required depth. In addition, a bit 130 for accommodating a guide pulley that guides the wire saw to an appropriate depth position, and a third cutting groove 103 for cutting the cut piece portion CP at approximately the center of the cut piece portion CP in the longitudinal direction are formed in advance.

[0009] In this type of cutting method, because annular cutting grooves 110, 110 are provided at the corners, the wire saw can move smoothly along the corners of the cut piece portion CP, and in addition, the expansion joint can be cut using relatively quiet equipment such as a rotary blade, core drill, and wire saw, without using a noisy chipping machine such as a breaker, so there is an advantage that complaints are unlikely to occur even when the expansion joint replacement work is performed near residential areas or buildings, etc. However, there is a problem in that a special core bit with a large thickness must be used, which increases the cost of the parts required for the core bit. For this reason, the following horizontal cutting method has been proposed.

[0010] 12 is an explanatory diagram illustrating, in plan view, the horizontal cutting method disclosed in Patent Document 2, which will be described later. In the figure, the same numbers are assigned to parts corresponding to those in FIGS. 10 and 11.

[0011] As shown in Figure 12(a), after forming the first kerfs 101, 101 and the second kerfs 102, 102 in the same manner as above to form a cut piece portion CP having a rectangular shape in a plan view, a plurality of (four in Figure 12) annular kerfs 201, 201, ..., 201, 201, ..., ..., ... are formed inside each of the four corners of the cut piece portion CP so that the annular kerfs 201, 201, ..., 201, 201, ..., ..., ... in each corner are close to each other. Here, the width of these annular kerfs 201, 201, ... is narrower than the width of the first kerfs 101, 101 and the second kerfs 102, 102, and they are formed using a core bit of a commonly available thickness.

[0012] Next, as shown in Figure 12(b), of the annular cutting grooves 201, 201, ..., 201, 201, ..., ..., ... in each corner, the cylindrical cores 210, 210, 210, 210 formed by the annular cutting grooves 201, 201, 201, 201 closest to the corner of the cut piece portion CP are cut and removed, and further, the corners around the cores 210, 210, 210, 210 are also cut and removed to form corner spaces KA, KA, KA, KA that connect to the corresponding first cutting grooves 101 and second cutting grooves 102.

[0013] Then, as before, for example, the wire saw cutting machine main body is positioned at approximately the center of the cut piece portion CP in the longitudinal direction, and the wire saw pulled out from the wire saw cutting machine main body is inserted to the bottom of one of the second cutting grooves 102, the corner spaces KA, KA located at both ends thereof, and the first cutting grooves 101, 101 communicating with both corner spaces KA, KA, and then, while maintaining the depth position of the wire saw, the wire saw is rotated and pulled back toward the wire saw cutting machine main body parallel to the surface of the floorboard, thereby performing a so-called horizontal cut, cutting one end of the cut piece portion CP into a strip shape at the required depth. A similar operation is performed on the other end of the cut piece portion CP, thereby cutting the entire length of the cut piece portion CP to the required depth.

[0014] In this method, as mentioned above, a commercially available core bit having a general thickness is used, so that the cost of parts can be kept as low as possible. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] Patent No. 3968380 [Patent Document 2] Patent No. 4705197 Summary of the Invention [Problem to be solved by the invention]

[0016] However, in such conventional cutting methods, it is necessary to form multiple annular cutting grooves 201, 201, ... close to each other inside the corners of the cut piece portion CP, so at least three or more annular cutting grooves 201, 201, ... must be formed. In addition, at each corner, the core 210 closest to the corner of the cut piece portion CP is cut and removed, and the periphery of this core 210 is also cut and removed to form a corner space KA that connects to the corresponding first cutting groove 101 and second cutting groove 102, so the number of operations required to achieve horizontal cutting is large and efficiency is low.

[0017] The present invention has been made in view of the above circumstances, and provides a cutting method with higher work efficiency. [Means for solving the problem]

[0018] (1) The cutting method according to the present invention involves cutting a required area of ​​an object to be cut that has been extended to an appropriate thickness to a required depth to obtain a strip-shaped cut piece, by forming a pair of first cutting grooves of a required depth corresponding to both long side edges of the cut piece at a predetermined location of the object to be cut, spaced apart in parallel to each other, and by providing a pair of second cutting grooves of approximately the same depth corresponding to both short side edges of the cut piece between both ends of the first cutting grooves, and moving a wire saw inserted into both first cutting grooves and one of the second cutting grooves in parallel to the surface of the object to be cut. After forming the two first cutting grooves, a first annular cutting groove and a second annular cutting groove, which are annular in plan view, are formed at each of the four corners of the cut piece portion, so that at least one of the first annular cutting grooves, the first annular cutting groove or the second annular cutting groove, is inscribed in a pair of the first and second cutting grooves that form the corresponding corners of the cut piece portion, and a part or all of the area surrounded by the other annular cutting groove, the second annular cutting groove, or an area surrounded by the first annular cutting groove. The cutting piece is characterized in that a part or all of the area overlaps with the area surrounded by the first annular cutting groove or the area surrounded by the second annular cutting groove, which is one of the annular cutting grooves, and a communicating recess that communicates the first cutting groove and the second cutting groove at the corner is formed by chipping off an appropriate portion of the area surrounded by the first annular cutting groove or the area surrounded by the second annular cutting groove that does not overlap with the area surrounded by the second annular cutting groove or the area surrounded by the first annular cutting groove, and in that, at the two corners on the other short side edge of the cut piece, a first annular cutting groove of a relatively large diameter is formed so as to be inscribed in the pair of first and second cutting grooves that constitute the corner, and a second annular cutting groove of a relatively small diameter is formed so as to be inscribed in the first cutting groove that constitutes the corner and to intersect with the second cutting groove that constitutes the corner, and chipping is performed on the area surrounded by the second annular cutting groove that protrudes from the area surrounded by the first annular cutting groove.

[0019] In the cutting method of the present invention, a required region of an elongated workpiece having an appropriate thickness is cut to a required depth to obtain a strip-shaped cut piece. A pair of first cutting grooves having a required depth corresponding to both long side edges of the cut piece are formed in parallel at a distance from each other at predetermined locations on the workpiece. A pair of second cutting grooves having approximately the same depth corresponding to both short side edges of the cut piece are also formed between both ends of the first cutting grooves. A wire saw inserted into both first cutting grooves and one of the second cutting grooves is then moved parallel to the surface of the workpiece to cut out the cut piece.

[0020] At this time, after forming both first cutting grooves, a first annular cutting groove and a second annular cutting groove, which are circular in plan view, are formed at each of the four corners that will form the four corners of the cut piece portion, so that at least one of the annular cutting grooves, the first annular cutting groove or the second annular cutting groove, is inscribed in the pair of first cutting grooves and second cutting grooves that form the corresponding corners of the cut piece portion, and so that part or all of the area surrounded by the other annular cutting groove, the second annular cutting groove, or part or all of the area surrounded by the first annular cutting groove, overlaps with the area surrounded by one of the annular cutting grooves, the first annular cutting groove or the area surrounded by the second annular cutting groove.

[0021] In such a case, the timing for forming the first annular cutting groove and the second annular cutting groove may be before or after forming the second cutting groove, but in the former case, even if the first annular cutting groove and the second annular cutting groove are formed wet by rotating the core bit while spraying water, this is preferable because it can prevent water from leaking from gaps and the like present in the floor of the viaduct, which is the object to be cut.

[0022] Then, by chipping an appropriate portion of the area surrounded by the first annular cutting groove or the area surrounded by the second annular cutting groove that does not overlap with the area surrounded by the second annular cutting groove or the area surrounded by the first annular cutting groove, a communicating recess is formed at the corner that connects the first cutting groove and the second cutting groove.

[0023] Since it is sufficient to form two annular cut grooves per corner at the four corners of the cut piece portion, work efficiency can be improved as much as possible. In addition, the chipping work performed to form the communicating recesses that communicate the first and second cut grooves at each corner only needs to be performed on an appropriate portion of the area surrounded by the first annular cut groove or the area surrounded by the second annular cut groove that does not overlap with the area surrounded by the second annular cut groove or the area surrounded by the first annular cut groove, i.e., on the entire area or a portion of either the area surrounded by the first annular cut groove or the area surrounded by the second annular cut groove, so the amount of chipping work can be reduced as much as possible, further improving work efficiency.

[0024] In this case, in the cutting method of the present invention, at the two corners on the other short side edge of the cut piece, a first annular cutting groove of a relatively large diameter is formed so as to be inscribed in each of the pair of first and second cutting grooves that make up the corner, and a second annular cutting groove of a relatively small diameter is formed so as to be inscribed in the first cutting groove that makes up the corner and to intersect with the second cutting groove that makes up the corner, and the area surrounded by the second annular cutting groove, which protrudes from the area surrounded by the first annular cutting groove, is chipped to form a connecting recess, thereby further reducing the amount of chipping work.

[0025] On the other hand, since both the first annular cutting groove and the second annular cutting groove are inscribed in the first cutting groove that forms the corner portion, the two annular cutting grooves do not extend beyond the first cutting groove, thereby avoiding defects from occurring around the cut piece portion of the cut object.

[0026] On the other hand, if the work is carried out on the center line side, not on the side of a side edge structure such as a ground guard or curbstone installed on an viaduct, even if a circular cutting groove is formed in the width direction of the viaduct, i.e., in the longitudinal direction of the first cutting groove, beyond the second cutting groove, no defects will occur because backfilling work will be carried out after removing the cut pieces.

[0027] Therefore, the first annular cut groove is formed so as to be inscribed in the second cut groove that constitutes the corner, and the second annular cut groove is formed so as to intersect with the second cut groove that constitutes the corner, i.e., so that a part of the second annular cut groove extends beyond the second cut groove, and the area surrounded by the second annular cut groove that protrudes from the area surrounded by the first annular cut groove is chipped to form a communicating recess. In this method, the area to be chipped is already divided by the second cut groove, so the chipping work can be carried out easily.

[0028] Furthermore, since the communication recess is formed following the first annular cutting groove, the portion of the communication recess that comes into contact with the wire saw is arc-shaped, allowing cutting work with the wire saw to be carried out as smoothly as possible.

[0029] (2) The cutting method according to the present invention is characterized in that the intersection of the second annular cutting groove with the second cutting groove and the contact point of the first annular cutting groove with the second cutting groove are made to approximately coincide with each other.

[0030] In the cutting method of the present invention, a second annular cutting groove of a relatively small diameter is formed at the two corners on the other short side edge of the cut piece, so that it is inscribed in the first cutting groove that constitutes the corner and intersects with the second cutting groove that constitutes the corner, and when chipping is performed on the area surrounded by the second annular cutting groove and the portion protruding from the area surrounded by the first annular cutting groove, the intersection of the second annular cutting groove with the second cutting groove and the contact point of the first annular cutting groove with the second cutting groove are made to approximately coincide.

[0031] This makes it possible to reduce the amount of work required to connect the communication recess and the second cutting groove as much as possible, thereby improving work efficiency.

[0032] Here, "approximately coincident" includes both a case where the intersection of the second annular kerf groove with the second kerf groove coincides with the tangent point of the first annular kerf groove with the first kerf groove, and a case where the distance between the intersection of the second annular kerf groove with the second kerf groove and the tangent point of the first annular kerf groove with the first kerf groove is approximately 3 cm or less. Even if the intersection and the tangent point do not coincide, the chipping operation can be easily performed as long as the distance between them is approximately 3 cm or less.

[0033] (3) The cutting method according to the present invention is characterized in that, in (1) or (2), at the two corners on one short side edge of the cut piece, a first annular cutting groove of a relatively large diameter is formed so as to be inscribed in the pair of first and second cutting grooves that make up the corner, and a second annular cutting groove of a relatively small diameter is formed so as to be inscribed in the pair of first and second cutting grooves that make up the corner, and chipping is performed on the area surrounded by the second annular cutting groove and the part that protrudes from the area surrounded by the first annular cutting groove.

[0034] In the cutting method of the present invention, at two corners on one short side edge of the cut piece, a first annular cut groove of relatively large diameter is formed so as to be inscribed in the pair of first and second cut grooves that make up the corner, and a second annular cut groove of relatively small diameter is formed so as to be inscribed in the pair of first and second cut grooves that make up the corner. Then, chipping is performed on the area surrounded by the second annular cut groove that protrudes from the area surrounded by the first annular cut groove.

[0035] In this configuration, the connecting recess can be formed simply by chipping off a portion of the area surrounded by the second annular cutting groove, which has a relatively small diameter, thereby further reducing the amount of chipping work and further improving work efficiency.

[0036] On the other hand, since both the first annular cutting groove and the second annular cutting groove are inscribed in the first cutting groove and the second cutting groove that form the corner portion, the corner portion of the cutting piece portion can be designed and positioned in close proximity to a side edge structure such as a ground guard or curbstone installed on an viaduct, and the first annular cutting groove and the second annular cutting groove can be formed without any problems.

[0037] Furthermore, since the communication recess is formed following the first annular cutting groove, the portion of the communication recess that comes into contact with the wire saw is arc-shaped, allowing cutting work with the wire saw to be carried out as smoothly as possible.

[0038] (4) The cutting method according to the present invention is characterized in that, when forming the first cutting groove and the second cutting groove using a circular rotary blade, the dimension from each contact point between the first annular cutting groove or the second annular cutting groove, which are inscribed in the pair of first cutting grooves and second cutting grooves constituting the corner portion, and the first cutting groove and the second cutting groove, respectively, to the intersection point between the first cutting groove and the second cutting groove constituting the corner portion, is set to be equal to or greater than the partial cutting area dimension, which is the distance between a first position on a vertical line on the periphery of the rotary blade passing through the center of the rotary blade, and a second position on the periphery of the rotary blade where the rotary blade can reach the object to be cut.

[0039] In the cutting method of the present invention, when the first cutting groove and the second cutting groove are formed using a circular rotating blade, the dimension from each contact point between the first annular cutting groove or the second annular cutting groove, which are inscribed in the pair of first cutting grooves and second cutting grooves that form the corner portion, and the first cutting groove and the second cutting groove that form the corner portion, to the intersection point of the first cutting groove and the second cutting groove that form the corner portion is made equal to or greater than the distance between a first position on a vertical line that is on the periphery of the rotating blade and passes through the center of the rotating blade, and a second position on the periphery of the rotating blade where the rotating blade can reach the object to be cut, i.e., the partial cutting area dimension, which is the distance from the first position to the second position in the vertical direction.

[0040] This allows the depths of the first and second cut grooves to be approximately the same as the depth of the communicating recesses that communicate with them, without the need for overcutting. Because there is no need to perform overcutting, the corners of the cut pieces can be designed and positioned in the immediate vicinity of edge structures provided on viaducts, for example. [Brief explanation of the drawings]

[0041] [Figure 1] 1 is an explanatory diagram illustrating a plan view of a cutting method according to the present invention; [Figure 2] 1 is an explanatory diagram illustrating a plan view of a cutting method according to the present invention; [Figure 3] FIG. 10 is a partially enlarged view of a corner of the cut piece portion on the edge structure side. [Figure 4] 10 is an explanatory view illustrating another example of forming the first annular cutting groove and the second annular cutting groove at the corner of the cutting piece portion on the edge structure side. FIG. [Figure 5] 10 is an explanatory view illustrating another example of forming the first annular cutting groove and the second annular cutting groove at the corner of the cutting piece portion on the edge structure side. FIG. [Figure 6] 10 is an explanatory view illustrating another example of forming the first annular cutting groove and the second annular cutting groove at the corner of the cutting piece portion on the edge structure side. FIG. [Figure 7] 10 is an explanatory view illustrating another example of forming the first annular cutting groove and the second annular cutting groove at the corner of the cutting piece portion on the edge structure side. FIG. [Figure 8] FIG. 10 is a partially enlarged view of a corner portion on the center line side of the cut piece portion. [Figure 9] FIG. 10 is an explanatory diagram illustrating the formation of cutting grooves by a rotary blade. [Figure 10] FIG. 1 is an explanatory diagram illustrating, in plan view, the horizontal cutting method disclosed in Patent Document 1. [Figure 11] FIG. 11 is a partially cutaway perspective view showing the structure of the viaduct including the expansion joint shown in FIG. 10 and its surrounding area. [Figure 12] FIG. 1 is an explanatory diagram illustrating the horizontal cutting method disclosed in Patent Document 2 in a plan view. DETAILED DESCRIPTION OF THE INVENTION

[0042] The cutting method according to the present invention will be described in detail with reference to the drawings. The cutting method described in this embodiment is an example for explaining the gist of the present invention, and it goes without saying that the present invention includes modifications and alterations within the scope of the gist of the present invention.

[0043] 1 and 2 are explanatory diagrams illustrating the procedure for carrying out the cutting method according to the present invention in a plan view, in which T is an expansion joint. Note that, in most cases, the replacement work for the expansion joint T is carried out for one of the inbound or outbound lanes of an elevated bridge, and then carried out in the same manner for the other lane, so here we will explain the case where the work is carried out for one lane.

[0044] As shown in FIG. 1(a), the expansion joint T is configured by, for example, arranging a first comb-like piece T1 and a second comb-like piece T2, each having a length corresponding to the width of the viaduct, with their teeth facing each other and their protrusions and recesses meshing with each other. This expansion joint T is installed between adjacent deck slabs F in the longitudinal direction of the viaduct so as to cover the gap provided across the entire width of the viaduct, and the expansion joint T is supported and fixed to both deck slabs F, F by anchor reinforcement (not shown). The expansion joint T is finished so that the surfaces of the pavement layers H, H laminated on the upper surfaces of the concrete deck slabs F, F are approximately flush with the upper surface of the expansion joint T. Meanwhile, edge structures CB, such as block- or wall-shaped curbs or ground guards, are erected on the edges of the deck slabs F, F corresponding to the side edges of the viaduct, and the ends of the expansion joint T extend close to the edge structures CB. The floor plates F, F and pavement layers H, H, etc. constitute the body to be cut.

[0045] To carry out the cutting method of the present invention to replace an expansion joint T in such a state, as shown in Figure 1(b), first cutting grooves 1,1 parallel to the longitudinal direction of the expansion joint T are formed at the opposing ends of adjacent floor panels F, F at positions spaced an appropriate distance from the expansion joint T. Here, the depth of the first cutting grooves 1,1 is set to an appropriate dimension larger than the thickness of the expansion joint T, for example, about 150 mm, and the width of the first cutting grooves 1,1 is set to a dimension slightly larger than the width of the annular wire saw used for horizontal cutting, for example, about 15 mm. Furthermore, both first cutting grooves 1,1 are formed using a disk-shaped rotating blade of the required thickness, and the first cutting grooves 1,1 of the required width are formed by stacking one or several of these rotating blades.

[0046] In addition, auxiliary grooves may be provided parallel to the first cutting grooves 1,1 at positions inside both first cutting grooves 1,1 to eliminate problems such as jamming of the wire saw inserted into the first cutting grooves 1,1 during cutting.

[0047] When the second cutting grooves 2, 2 are respectively provided between both ends of the first cutting grooves 1, 1 formed in this way as described later, a rectangular cutting piece portion CP (see FIG. 2(d) for both) is formed. A core drill is used at the four corners of this cutting piece portion CP to form the first annular cutting grooves 10, 10, 10, 10 and the second annular cutting grooves 20, 20, 20, 20, which are annular in plan view, at least one of the first annular cutting grooves 10, 10, 10, 10 or the second annular cutting grooves 20, 20, 20. 0,20 are inscribed in a pair of first cutting grooves 1,1,1,1 and second cutting grooves 2,2,2,2 which form the corresponding four corners of the cut piece portion CP, respectively, and part or all of the area surrounded by the other annular cutting groove, the second annular cutting groove 20,20,20,20, or the area surrounded by the first annular cutting grooves 10,10,10,10, are formed to overlap with the area surrounded by one of the annular cutting grooves, the first annular cutting grooves 10,10,10,10, or the area surrounded by the second annular cutting grooves 20,20,20,20,20.

[0048] The width of the first annular cutting grooves 10, 10, 10, 10 and the second annular cutting grooves 20, 20, 20, 20 is smaller than the width of the wire saw, allowing the use of commercially available core bits of standard thickness. The depth of the first annular cutting grooves 10, 10, 10, 10 and the second annular cutting grooves 20, 20, 20, 20 is the same as the depth of the first cutting groove 1, allowing the cut pieces CP to be obtained with the required depth.

[0049] 3 is a partially enlarged view of the corner of the cut piece portion CP on the side of the edge structure CB, in which the same numbers are assigned to parts corresponding to those shown in FIG.

[0050] As shown in Figure 3, a pair of first and second annular cutting grooves 10 and 20 are formed in one corner of the cut piece portion CP on the edge structure side, and in this example, the first annular cutting groove 10, which has a relatively large diameter, is cut so as to be inscribed within the pair of first and second cutting grooves 1 and 2 that constitute the corner of the cut piece portion CP.

[0051] In addition, in this example, a second annular cutting groove 20 having a relatively small diameter is inscribed in each of the pair of first cutting grooves 1 and second cutting grooves 2 that constitute the one corner portion, and most of the area surrounded by the second annular cutting groove 20 overlaps with the area surrounded by the first annular cutting groove 10, while the other area E1 that does not overlap with the area surrounded by the second annular cutting groove 20 protrudes from the area surrounded by the first annular cutting groove 10 toward the one corner.

[0052] At this time, the contact point P21 between the second annular cut groove 20 and the first cut groove 1 and the contact point P22 between the second annular cut groove 20 and the second cut groove 2 are located slightly closer to one corner than the contact point P11 between the first annular cut groove 10 and the first cut groove 1 and the contact point P12 between the first annular cut groove 10 and the second cut groove 2. In addition, a second annular cut groove protrusion E1, which is a part of the area surrounded by the second annular cut groove 20 and which protrudes from the area surrounded by the first annular cut groove 10, has a crescent shape. The part of the area surrounded by the second annular cut groove 20 other than the second annular cut groove protrusion E1 is a second annular cut groove overlapping portion E2.

[0053] Such a first annular cutting groove 10 and a second annular cutting groove 20 are formed at each of the two corners of the cutting piece portion CP on the edge structure CB side, but since only two annular cutting grooves are required to be formed by the core drill per corner of the cutting piece portion CP, work efficiency can be improved as much as possible.

[0054] 4 to 7 are explanatory views illustrating other examples of forming the first annular cutting groove 10 and the second annular cutting groove 20 at the corner of the cut piece portion CP on the edge structure side. In each drawing, parts corresponding to those shown in FIG. 3 are assigned the same numbers.

[0055] As shown in FIGS. 4 to 6 , the second annular kerf groove 20 is formed within the region surrounded by the first annular kerf groove 10, and the entire region surrounded by the second annular kerf groove 20 is defined as the second annular kerf groove overlap portion E2. In this case, the first annular kerf groove 10 and the second annular kerf groove 20 may be formed concentrically, as shown in FIG. 4 . Alternatively, as shown in FIG. 5 , the second annular kerf groove 20 may be formed within the region surrounded by the first annular kerf groove 10 in a region spaced apart from the corner with respect to a line L1 connecting the contact points P11 and P12 between the first annular kerf groove 1 and the second annular kerf groove 2 and the first annular kerf groove 10. Alternatively, as shown in FIG. 6 , the second annular kerf groove 20 may be formed within the region surrounded by the first annular kerf groove 10 so that a portion of the second annular kerf groove 20 protrudes toward the corner with respect to the line L1 connecting the contact points P11 and P12 between the first annular kerf groove 1 and the second annular kerf groove 2 and the first annular kerf groove 10.

[0056] Furthermore, as shown in FIG. 7, the second annular cutting groove 20 is formed to have the aforementioned second annular cutting groove protrusion E1, but the second annular cutting groove protrusion E1 can also be formed to protrude in a direction away from the corner.

[0057] On the other hand, on the side of the cut piece portion CP opposite to the edge structure CB side, that is, on the two corners on the center line side, the first annular cut groove 10 and the second annular cut groove 20 are formed as follows.

[0058] 8 is a partial enlarged view of the corner portion on the center line side of the cut piece portion CP. In the figure, parts corresponding to those shown in FIG. 1(b) are assigned the same numbers.

[0059] As shown in Figure 8, a first annular cutting groove 10 having a relatively large diameter is cut into one corner of the cut piece portion CP on the center line side so as to be inscribed in a pair of first cutting groove 1 and second cutting groove 2 that constitute the corner of the cut piece portion CP.

[0060] In addition, a second annular cutting groove 20 having a relatively small diameter is inscribed in at least the first cutting groove 1 of the pair of first cutting grooves 1 and second cutting grooves 2 that constitute the one corner of the cut piece portion CP, and most of the area surrounded by the second annular cutting groove 20 is overlapped with the area surrounded by the first annular cutting groove 10 to form a second annular cutting groove overlapping portion E2, and the other area of ​​the area surrounded by the second annular cutting groove 20 that is not overlapped is protruded from the area surrounded by the first annular cutting groove 10 toward the one corner, forming a second annular cutting groove protruding portion E1.

[0061] At this time, the second annular cut groove 20 may be inscribed in the second cut groove 2, just as in the corner of the cut piece portion CP on the side of the edge structure CB described above, but since the edge structure CB is not present in the vicinity of the corner of the center line side of the cut piece portion CP, it can be made to protrude outward from the second cut groove 2 that constitutes the corner, as shown in Fig. 8. This makes it possible to position the intersection P23 between the second annular cut groove 20 and the second cut groove 2 at the same position as or in the vicinity of the position of the contact point P12 of the first annular cut groove 10 with the second cut groove 2, thereby minimizing the chipping work described below and further improving work efficiency.

[0062] Here, "nearby" refers to a case where the distance between the intersection P23 of the second annular cut groove 20 with the second cut groove 2 and the contact point P12 of the first annular cut groove 10 with the second cut groove 2 is approximately 3 cm or less. Even if the intersection P23 and the contact point P12 do not coincide, the chipping operation can be easily carried out as long as the distance between them is approximately 3 cm or less.

[0063] As before, the point of contact P21 between the second annular cut groove 20 and the first cut groove 1 is located slightly closer to the corner than the point of contact P11 between the first annular cut groove 10 and the first cut groove 1. On the other hand, the point of contact P21 between the second annular cut groove 20 and the first cut groove 1 can be located at any position between the position of the point of contact P11 between the first annular cut groove 10 and the first cut groove 1 and the intersection of the first cut groove 1 and the second cut groove 2 that form the corner, but it is preferable to position the point of contact P21 between the second annular cut groove 20 and the first cut groove 1 closer to the point of contact P11 between the first annular cut groove 10 and the first cut groove 1, as this can further reduce the amount of chipping work.

[0064] In this example, the intersection P23 between the second annular cutting groove 20 and the second cutting groove 2 is located at the same position as or near the position of the contact point P12 of the first annular cutting groove 10 to the second cutting groove 2. However, the present invention is not limited to this. Regardless of the distance between the intersection P23 and the contact point P12, at the two corners on the center line side of the cut piece portion CP, a first annular cutting groove 10 with a relatively large diameter is formed so as to be inscribed in each of the pair of first cutting grooves 1 and second cutting grooves 2 that constitute the corner, and a second annular cutting groove 20 with a relatively small diameter is formed so as to be inscribed in the first cutting groove 1 that constitutes the corner and to intersect with the second cutting groove 2 that constitutes the corner, i.e., so that a part of the second annular cutting groove 20 extends beyond the second cutting groove 2. The area surrounded by the second annular cutting groove 20 and the part that protrudes from the area surrounded by the first annular cutting groove 10 is chipped to form a connecting recess RT.

[0065] In this case, the first annular cutting groove 10 and the second annular cutting groove 20 are both inscribed in the first cutting groove 1 that forms the corner portion, so that both annular cutting grooves 10, 20 do not extend beyond the first cutting groove 1, thereby avoiding defects from occurring around the cut piece portion CP of the floorboard.

[0066] On the other hand, for example, when this is done on the center line side of an viaduct, even if a circular cutting groove is formed in the width direction of the viaduct, i.e., in the longitudinal direction of the first cutting groove 1, beyond the second cutting groove 2, no defects will occur because backfilling work will be carried out after removing the cut piece portion CP.

[0067] Therefore, the first annular cut groove 10 is formed so as to be inscribed in the second cut groove 2 that constitutes the corner, and the second annular cut groove 20 is formed so as to intersect with the second cut groove 2 that constitutes the corner, i.e., so that a part of the second annular cut groove 20 extends beyond the second cut groove 2, and a communicating recess is formed by chipping the area surrounded by the second annular cut groove 20 that protrudes from the area surrounded by the first annular cut groove 10. In this method, the area to be chipped is already divided by the second cut groove 2, so that the chipping work can be carried out easily.

[0068] In this way, in the cutting method of the present invention, even at the corners on the center line side of the cut piece portion CP, only two annular cutting grooves are required to be formed by the core drill per corner on the center line side of the cut piece portion CP, thereby improving work efficiency as much as possible.

[0069] However, since both the first cutting groove 1 and the second cutting groove 2 are formed by rotating a circular rotary blade while moving it in one direction, it is not possible to make the entire range in the direction of movement of the rotary blade the required depth dimension.

[0070] Fig. 9 is an explanatory diagram illustrating the formation of cutting grooves by a rotary blade, in which RB is a disk-shaped rotary blade. Note that in Fig. 9, the teeth provided on the periphery of the rotary blade RB are omitted.

[0071] As shown in FIG. 9 , the rotating blade RB is a disk. Therefore, for example, when the rotating blade RB moves from left to right in the drawing, the range in which the object M is cut to the required depth d by the rotating blade RB extends up to a first position P31 on the periphery of the rotating blade RB, which is on a vertical line passing through the center O of the rotating blade RB. The radius of the rotating blade RB is r; the dimension of the area where the rotating blade RB cuts a portion of the object M but does not reach the required depth d, i.e., the distance between the first position P31 and a second position P32 on the periphery of the rotating blade RB where the rotating blade RB can reach the object M, is x; and the angle between the first position P31, the center O, and the second position P32 is θ. Therefore, cos θ = (rd) / r. Therefore, by substituting the values ​​of the radius r and the depth d of the rotating blade RB into this, the angle θ between the first position P31, the center O, and the second position P32 can be calculated. The value of the partial cutting region dimension x can be calculated by substituting the obtained θ into the following equation (1):

[0072]

number

[0073] In the cutting method according to the present invention, at the corners of the cut piece portion CP on the side of the edge structure CB and at the corners of the cut piece portion CP on the side of the center line, at least the distance between the points of contact between the first and second cut grooves 1 and 2 constituting the corners and the first annular cut groove 10, and the point of intersection between the first and second cut grooves 1 and 2 constituting the corners, is set to a value equal to or greater than the partial cut area dimension x. As a result, at any corner, a groove of a required depth is formed that connects the first cut groove 1 constituting the corner, through the first annular cut groove 10, to the second cut groove 2.

[0074] In addition, when a portion of the area surrounded by the second annular cutting groove 20 protrudes toward the corner from the area surrounded by the first annular cutting groove 10, as shown in Figure 3, the dimension between the two contact points P21, P22 between the first and second annular cutting grooves 1 and 2 that constitute the corner and the second annular cutting groove 20 and the intersection point between the first and second cutting grooves 1 and 2 that constitute the corner, or as shown in Figure 8, the dimension between the contact point P21 between the first and second annular cutting grooves 1 and 20 that constitute the corner and the intersection point P23 between the second and second annular cutting grooves 2 and 20 and the intersection point between the first and second cutting grooves 1 and 2 that constitute the corner may all be set to a value greater than the partial cutting area dimension x.

[0075] In such a case, the chipping work can be reduced as much as possible.

[0076] Next, as shown in Figure 1(b), in order to form pulley recesses 31, 31 (see Figure 2(c)) for fitting pulleys that change the posture of the wire saw in the inner regions of both first cutting grooves 1,1 at approximately the center of the longitudinal direction of the first cutting grooves 1,1, multiple (six in this example) third annular cutting grooves 30, 30, ..., 30, 30, ... are formed by partially overlapping each other so that the depth dimensions are the same as the depth dimensions of the first cutting grooves 1,1 and the length and width dimensions are greater than the length and width dimensions of the pulleys.

[0077] In this example, the pulley recess 31 is formed by overlapping a portion of a plurality of third annular cutting grooves 30, 30, ... with each other, but the present invention is not limited to this, and the pulley recess 31 can also be formed using a rotating blade.

[0078] Furthermore, if necessary, fourth annular cutting grooves 40, 40, 40, 40 are formed with the same depth as the first cutting grooves 1, 1 in order to form pressure roller recesses 41, 41, 41, 41 (see Figure 2(c)) for fitting pressure rollers that press the wire saw to the required depth position in the inner region of the first cutting grooves 1, 1 at an appropriate position between the pulley recess 31 and the first or second annular cutting grooves 10, 20.

[0079] The order in which the third annular cutting grooves 30, 30, ... are formed and the order in which the fourth annular cutting grooves 40, 40, 40, 40 are formed may be arbitrary, and the order in which the first annular cutting grooves 10, 10, 10, 10 and the second annular cutting grooves 20, 20, 20, 20 and the order in which the third annular cutting grooves 30, 30, ... and the fourth annular cutting grooves 40, 40, 40, 40 may also be arbitrary.

[0080] Next, as shown in Figures 2(c), 3 and 8, the second annular cutting groove protrusions E1, E1, E1, E1 formed at the four corners of the cut piece portion CP, and, if necessary, the areas E10, E10 surrounded by the first cutting groove 1 or the second cutting groove 2 and the first annular cutting groove 10 and the second annular cutting groove 20, are removed using a chipping tool such as a crowbar to form connecting recesses RT, RT, RT, RT, which have the same depth as the depth of the first cutting groove 1,1 and the second cutting groove 2,2 and which allow the wire saw to connect from the first cutting groove 1 or the second cutting groove 2 through the corner to the second cutting groove 2 or the first cutting groove 1.

[0081] In addition, in the case where a portion of the area surrounded by the second annular cutting groove 20 is protruded toward the corner from the area surrounded by the first annular cutting groove 10 as described above to form the second annular cutting groove protrusion SC1, as shown in Figure 3, the two contact points P21, P22 between the first and second annular cutting grooves 1 and 2 constituting the corner and the second annular cutting groove 20, or as shown in Figure 8, the distance between the contact point P21 between the first and second annular cutting grooves 1 and 20 constituting the corner and the intersection point P23 between the second and second annular cutting grooves 2 and 20 constituting the corner is set to a value equal to or greater than the partial cutting area dimension x described above, so that the communicating recess RT can be formed without actually chipping the area E10 surrounded by the first and second annular cutting grooves 1 or 2 and the first and second annular cutting grooves 10 and 20.

[0082] On the other hand, in another example in which the first annular cutting groove 10 and the second annular cutting groove 20 are arranged so that the second annular cutting groove protrusion E1 protruding toward the corner is not formed, a connecting recess RT is formed as shown in Figures 4 to 7.

[0083] That is, when the second annular cutting groove 20 is formed within the area surrounded by the first annular cutting groove 10, and the entire area surrounded by the second annular cutting groove 20 becomes the second annular cutting groove overlap portion E2, and when the first annular cutting groove 10 and the second annular cutting groove 20 are formed concentrically as shown in Figure 4, chipping is performed on an appropriate portion of the donut-shaped area surrounded by the first annular cutting groove 10 that does not overlap with the area surrounded by the second annular cutting groove 20, including the line L1 connecting the two contact points P11 and P12 between the first annular cutting groove 1 and the second cutting groove 2 and the first annular cutting groove 10.

[0084] In the same case as above, even if the second annular cutting groove 20 is formed within the area surrounded by the first annular cutting groove 10 in an area away from the corner with respect to the line connecting the two contact points P11, P12 between the first annular cutting groove 1 and the second annular cutting groove 2 and the first annular cutting groove 10, as shown in Figure 5, chipping is performed on an appropriate portion of the area surrounded by the first annular cutting groove 10 that does not overlap with the area surrounded by the second annular cutting groove 20, including the line connecting the two contact points P11, P12 between the first annular cutting groove 1 and the second annular cutting groove 2 and the first annular cutting groove 10, as before.

[0085] Furthermore, in the same case as above, as shown in Figure 6, when the second annular cutting groove 20 is formed within the area surrounded by the first annular cutting groove 10 so that a portion of the second annular cutting groove 20 protrudes toward the corner with respect to the line L1 connecting the two contact points P11, P12 between the first annular cutting groove 1 and the second annular cutting groove 2 and the first annular cutting groove 10, as before, chipping is performed on an appropriate portion of the donut-shaped area surrounded by the first annular cutting groove 10 that does not overlap with the area surrounded by the second annular cutting groove 20, including the line connecting the two contact points P11, P12 between the first annular cutting groove 1 and the second cutting groove 2 and the first annular cutting groove 10.

[0086] On the other hand, as shown in Figure 7, when the second annular cutting groove 20 is formed to have the above-mentioned second annular cutting groove protrusion E1, but the second annular cutting groove protrusion E1 is formed to protrude in a direction away from the corner, chipping is performed on an appropriate portion of the area surrounded by the first annular cutting groove 10 that does not overlap with the area surrounded by the second annular cutting groove 20, including the line L1 connecting the two contact points P11, P12 between the first annular cutting groove 1 and the second cutting groove 2 and the first annular cutting groove 10.

[0087] In this way, in the cutting method of the present invention, the area surrounded by the first annular cutting groove 10 is overlapped with part or all of the area surrounded by the second annular cutting groove 20, and a chipping operation is performed on an appropriate area that is not overlapped with the area surrounded by the first annular cutting groove 10 or the area surrounded by the second annular cutting groove 20, thereby forming the communicating recess RT, thereby reducing the amount of chipping work as much as possible and further improving work efficiency.

[0088] Furthermore, in the case where a second annular cutting groove protrusion E1 protruding toward the corner is formed as shown in Figures 3 and 8, by performing the chipping work as described above to form the connecting recess RT, the corners of the cut piece portion CP are formed into an arc shape, which is preferable because it allows the cutting work using a wire saw to be carried out as smoothly as possible.

[0089] On the other hand, as shown in Figure 2(c), the area surrounded by the third annular cutting grooves 30, 30, ... and the area surrounded by the fourth annular cutting grooves 40, 40, 40, 40 are all chipped to form pulley recesses 31, 31 and pressure roller recesses 41, 41, 41, 41.

[0090] Next, as shown in Figure 2(d), second cutting grooves 2,2 having the same depth as the first cutting grooves 1,1 are formed between the ends of the first cutting grooves 1,1, thereby forming a strip-shaped cut piece portion CP when viewed in a plane.

[0091] Furthermore, a third cutting groove 3 is cut between the approximate centers of the opposing pulley recesses 31, 31, and a fourth cutting groove 4, 4 is cut between the approximate centers of the opposing pressure roller recesses 41, 41, 41, 41, so that the grooves are parallel to the second cutting grooves 2, 2 and have the same depth as the first cutting grooves 1, 1.

[0092] In this way, by forming the first annular cutting groove 10,10,..., the second annular cutting groove 20,20,..., the third annular cutting groove 30,30,..., and the fourth annular cutting groove 40,40,40,40 before forming the second cutting groove 2,2, the third cutting groove 3, and the fourth cutting groove 4,4, even if these first to fourth annular cutting grooves 10,10,..., 20,20,..., 30,30,..., 40,40,40,40,40 are formed using a wet method in which the core bit is rotated while water is sprayed, it is possible to prevent the water from leaking downward from the gap portion of the viaduct.

[0093] In addition, since the first annular cutting grooves 10,10,..., the second annular cutting grooves 20,20,..., the third annular cutting grooves 30,30,..., and the fourth annular cutting grooves 40,40,40,40 are formed before the second cutting grooves 2,2, the third cutting grooves 3, and the fourth cutting grooves 4,4, the cutting distances of the second cutting grooves 2,2, the third cutting grooves 3, and the fourth cutting grooves 4,4 are relatively short, thereby making the cutting work more efficient.

[0094] In addition, if the first to fourth annular cutting grooves 10,10,..., 20,20,..., 30,30,..., 40,40,40,40,40 can be formed using a dry core bit, the first annular cutting grooves 10,10,..., the second annular cutting grooves 20,20,..., the third annular cutting grooves 30,30,..., and the fourth annular cutting grooves 40,40,40,40 may be formed after the second annular cutting grooves 2,2, the third annular cutting grooves 3, and the fourth annular cutting grooves 4,4.

[0095] Then, a wire saw body (not shown) is placed near the pulley recesses 31, 31, a pulley is fitted into the pulley recesses 31, 31, the annular wire saw pulled out from the wire saw body is positioned parallel to the cut piece portion CP, the wire saw in this position is inserted into the second cutting groove 2, the communicating recesses RT, RT, and the bottom of the first cutting grooves 1, 1, and wrapped around the part of the cut piece portion CP on the edge structure CB side or the part on the center line side, and the wire saw is turned and pulled back toward the wire saw body, thereby cutting out approximately half of the cut piece portion CP approximately horizontally to the required depth. Next, the orientation of the wire saw body is reversed, and the same operation as before is performed to cut out the expansion joint T together with the remaining approximately half of the cut piece portion CP.

[0096] In addition, the portion remaining near the corner where the first cutting groove 1,1 and the second cutting groove 2,2 intersect after the chipping operation as described above is removed using a chipping tool when forming the connecting recess RT or after removing the cut piece portion CP.

[0097] In the case shown in Figure 2(d), the cut piece portion CP is divided into four by the third cutting groove 3 and the fourth cutting groove 4,4. After each piece is lifted and removed using a crane or similar, a new expansion joint is installed, concrete is filled around it to the required depth and allowed to harden, and the surface is paved, completing the replacement of the expansion joint.

[0098] In this type of cutting method, the connecting recesses RT, RT, RT, RT are provided at the corners of the cut piece portion CP, which allows the wire saw to run smoothly through the corners. In addition, the expansion joint can be cut using relatively quiet equipment such as a rotary blade, core drill, and wire saw, without using a noisy chipping machine such as a breaker. Therefore, complaints are unlikely to arise even when the expansion joint replacement work is carried out in a residential area or near a building, etc.

[0099] In addition, the first annular cutting grooves 10, 10, ..., the second annular cutting grooves 20, 20, ..., the third annular cutting grooves 30, 30, ..., and the fourth annular cutting grooves 40, 40, 40, 40 are all formed using core bits with thickness dimensions that are widely and commonly available on the market, so that component costs can be kept as low as possible.

[0100] Furthermore, as mentioned above, one of the annular cutting grooves, the first annular cutting groove 10,10,10,10 or the second annular cutting groove 20,20,20,20, is inscribed in the first cutting groove 1,1,1,1 and the second cutting groove 2,2,2,2, which constitute the corresponding four corners of the cut piece portion CP, respectively, and part or all of the area surrounded by the other annular cutting groove, the second annular cutting groove 20,20,20,20, or the area surrounded by the first annular cutting groove 10,10,10,10, is formed to overlap with the area surrounded by the one of the annular cutting grooves, the first annular cutting groove 10,10,10,10, or the area surrounded by the second annular cutting groove 20,20,20,20,. Therefore, only two annular cutting grooves need to be formed by the core drill per corner of the cut piece portion CP, thereby improving work efficiency as much as possible. [Explanation of symbols]

[0101] 1 1st cutting groove 2 2nd cutting groove 3 Third cutting groove 4 4th cutting groove 10 First circular cutting groove 20 Second circular cutting groove 30 Third circular cutting groove 40 4th circular cutting groove T-expansion joint CP cut section RT Connecting recess CB edge structure

Claims

1. A cutting method for obtaining strip-shaped cut pieces by cutting a required region of an object to be cut that has been extended to an appropriate thickness to a required depth, comprising forming a pair of first cutting grooves of required depth corresponding to both long side edges of the cut piece at predetermined locations of the object to be cut, spaced apart in parallel, and spaced apart from each other, and forming a pair of second cutting grooves of approximately the same depth corresponding to both short side edges of the cut piece between both ends of the first cutting grooves, and moving a wire saw inserted into both first cutting grooves and one of the second cutting grooves in parallel with the surface of the object to be cut, After forming the two first cutting grooves, a first annular cutting groove and a second annular cutting groove, which are annular in plan view, are formed at each of the four corners that will form the four corners of the cut piece portion, such that at least one of the first annular cutting grooves, i.e., the first annular cutting groove or the second annular cutting groove, is inscribed in the pair of first cutting grooves and second cutting grooves that form the corresponding corners of the cut piece portion, and a part or all of the area surrounded by the other annular cutting groove, i.e., the second annular cutting groove, or a part or all of the area surrounded by the first annular cutting groove, overlaps with the area surrounded by one of the annular cutting grooves, i.e., the first annular cutting groove or the second annular cutting groove; In forming a communication recess that communicates the first cut groove and the second cut groove at the corner by chipping an appropriate portion of the area surrounded by the first annular cut groove or the area surrounded by the second annular cut groove that does not overlap the area surrounded by the second annular cut groove or the area surrounded by the first annular cut groove, At the two corners on the other short side edge of the cut piece portion, a first annular cutting groove having a relatively large diameter is formed so as to be inscribed in the pair of first cutting groove and second cutting groove that form the corner portion, a second annular kerf having a relatively small diameter is formed so as to be inscribed in the first kerf that constitutes the corner and to intersect with the second kerf that constitutes the corner; The area surrounded by the second annular cutting groove is chipped, and the area protruding from the area surrounded by the first annular cutting groove is chipped. A cutting method characterized by:

2. 2. The cutting method according to claim 1, wherein an intersection of the second annular kerf with the second kerf and a contact point of the first annular kerf with the second kerf are made to substantially coincide with each other.

3. At the two corners on one short side edge of the cut piece portion, a first annular cutting groove having a relatively large diameter is formed so as to be inscribed in the pair of first cutting groove and second cutting groove that form the corner portion, a second annular cutting groove having a relatively small diameter is formed so as to be inscribed in the pair of first cutting groove and second cutting groove that form the corner portion, The area surrounded by the second annular cutting groove is chipped, and the area protruding from the area surrounded by the first annular cutting groove is chipped. The cutting method according to claim 1.

4. At the two corners on one short side edge of the cut piece portion, a first annular cutting groove having a relatively large diameter is formed so as to be inscribed in the pair of first cutting groove and second cutting groove that form the corner portion, a second annular cutting groove having a relatively small diameter is formed so as to be inscribed in the pair of first cutting groove and second cutting groove that form the corner portion, The area surrounded by the second annular cutting groove is chipped, and the area protruding from the area surrounded by the first annular cutting groove is chipped. The cutting method according to claim 2.

5. When the first cutting groove and the second cutting groove are formed using a disk-shaped rotary blade, The dimension from each contact point between the first annular cutting groove or the second annular cutting groove, which are inscribed in the pair of first cutting grooves and second cutting grooves constituting the corner portion, and the first cutting groove or the second cutting groove constituting the corner portion, to the intersection point of the first cutting groove and the second cutting groove constituting the corner portion is set to be equal to or larger than the dimension of the partial cutting area, which is the distance between a first position on a vertical line that is on the periphery of the rotary blade and passes through the center of the rotary blade, and a second position on the periphery of the rotary blade where the rotary blade can reach the object to be cut. The cutting method according to any one of claims 1 to 4.

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