Stem-driven anchor and method for removing the same

Abstract

To provide a core rod driving anchor which can be easily removed, and a method for removing the core rod driving anchor.SOLUTION: A core rod 20 is driven into a center hole 11 of a body 10 inserted into a prepared hole W1 of a fixed object W, so that an expansion part 14 formed with a slit 13 of the body 10 is expanded to be fixed to the fixed object W, and a head part 21 of the core rod 20 is formed with a torque receiving part 21a capable of receiving turning torque from the outside.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a core rod-driven anchor used when attaching an article to a target object such as a concrete structure, and a method for removing the core rod-driven anchor. [Background technology]

[0002] Core rod anchors are used to attach various items such as equipment, piping, racks, handrails, brackets, etc. to the concrete skeleton that makes up a building or structure.

[0003] For example, the mandrel anchor disclosed in Patent Document 1 involves inserting the body into a pilot hole provided in a concrete structure and driving the mandrel into the body until the head of the mandrel abuts one end of the body, causing the expansion portion at the other end of the body to expand radially and bite into the inner circumferential surface of the pilot hole, thereby attaching the mandrel anchor to the concrete structure in a state where it is prevented from slipping out. This mandrel anchor and nut can be used to attach an article to the concrete structure. In this way, the mandrel anchor can be easily attached by driving the mandrel into the body, and the driving status can be easily checked from the outside. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-232255 A (page 5, Figure 5) [Patent Document 2] JP 2018-89709 A (page 6, Figure 15) Summary of the Invention [Problem to be solved by the invention]

[0005] However, with core rod-driven anchors such as those described in Patent Document 1, there is an increasing demand for their removal from concrete structures. In particular, with male thread anchors, cutting off the protruding portion with a grinder or the like can be problematic, but cutting chips fly off and the lower part of the anchor is left in the prepared hole. While cutting using a dedicated cutting tool has been proposed, the lower part of the anchor is still left in the prepared hole. Furthermore, while a dedicated extraction jig has been proposed, such as in Patent Document 2, considerable force is required to remove the core rod. After many years of research into core rod removal, the inventors discovered a mechanism for easily removing the core rod using a completely new method and structure, which is described below.

[0006] The present invention has been made in light of these problems, and aims to provide a core rod-driven anchor that can be easily removed and a method for removing the core rod-driven anchor. [Means for solving the problem]

[0007] In order to solve the above problems, the core rod-driven anchor of the present invention has the following features: A core rod driving type anchor in which a core rod is driven into a center hole of a body inserted into a pilot hole of a fixed body, thereby expanding an expansion portion having a slit formed in the body and fixing the anchor to the fixed body, The head of the core rod is characterized by being formed with a torque receiving portion capable of receiving a rotational torque from the outside. According to this feature, by engaging a tool with the torque receiving portion at the head of the mandrel and applying a rotational torque to the mandrel, the mandrel that is biting into the body can be peeled off and the mandrel can be easily removed from the body, thereby making it easy to remove the anchor from the fixed object.

[0008] In use, the core rod receives an elastic restoring force in the narrowing direction from the expansion portion. According to this feature, by applying a rotational torque to the core rod, the core rod receives an elastic restoring force in the constriction direction from the expansion portion, and is therefore more likely to float in the removal direction.

[0009] The core rod has a tapered portion whose diameter gradually decreases, and the tapered portion is constricted by the expanded portion. According to this feature, by applying a rotational torque to the core rod, the core rod is more likely to float in the direction of removal from the expansion portion.

[0010] The inner periphery of the expansion portion is characterized by having a stepped shape in which the diameter decreases toward the tip. According to this feature, when in use, the areas corresponding to the corners of the steps are scattered in the axial direction and bite into the core rod, so that the bite can be released by rotating the core rod with a relatively small torque.

[0011] The torque receiving portion is characterized in that the side of the head portion has a flat shape. According to this feature, it is easy to pull out the core rod by applying a force from the side to the head portion.

[0012] The side of the head is characterized by being hexagonal when viewed from above. This feature allows a rotational torque to be applied to the mandrel using a conventional tool.

[0013] A bulge is provided above the torque receiving portion. According to this feature, the bulging portion is struck with a hammer or the like when the bolt is driven in, so that deformation of the torque receiving portion due to the strike can be avoided.

[0014] The torque receiving portion is characterized by being a recessed hole provided at the top of the head portion. This feature allows the tool to be accessed from above the head, resulting in excellent workability.

[0015] A method for removing a core-rod-driving type anchor fixed to a fixed body, in which a core rod is driven into a central hole of a body inserted into a pilot hole of a fixed body, so that the core rod receives an elastic restoring force in a narrowing direction from an expanded portion of the body where a slit is formed, and the expanded portion expands, The method is characterized by including a step of applying a rotational torque to the head of the core rod from the outside to rotate the core rod. According to this feature, by rotating the core rod, the core rod that has bitten into the body can be separated and the core rod can be lifted up relative to the body. [Brief explanation of the drawings]

[0016] [Figure 1] 1A is a top view showing a core rod-driven anchor in Example 1 of the present invention, FIG. 1B is a side view of the same, and FIG. 1C is a bottom view of the same. [Figure 2] (a) is a side view showing the body, (b) is a side cross-sectional view of the same, and (c) is a side view showing the core rod. [Figure 3] 1 is a schematic diagram showing the procedure for installing a core rod-driven anchor. FIG. [Figure 4] 1(a) is a schematic cross-sectional view showing the state before the core rod is driven in, and FIG. 1(b) is a schematic cross-sectional view showing the state after the core rod is driven in. FIG. [Figure 5] FIG. 10 is a schematic diagram showing the procedure for removing the core rod-driven anchor. [Figure 6] FIG. 10 is a schematic cross-sectional view showing the state in which the driven core rod is rotated. [Figure 7] 10 is a graph showing a load acting when the core rod is pulled out. [Figure 8] 10(a) to 10(e) are schematic diagrams showing modified examples 1 to 5 of the head portion of the mandrel of the mandrel-driven anchor. [Figure 9] FIG. 7 is a schematic cross-sectional view showing a modified example 7 of the head portion of the mandrel of the mandrel-driven anchor. [Figure 10] FIG. 10 is a schematic cross-sectional view showing modified example 8 of the head portion of the mandrel of the mandrel-driven anchor. [Figure 11] FIG. 9 is a schematic diagram showing a modified example 9 of the core rod-driven anchor. DETAILED DESCRIPTION OF THE INVENTION

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A core rod-driven anchor and a method for removing the core rod-driven anchor according to the present invention will be described below with reference to the following examples. [Example]

[0018] The core rod driven anchor and the method for removing the core rod driven anchor according to the embodiment will be described with reference to Figures 1 to 7. In the following description, the top and bottom of the plane of the paper in Figure 3 will be the top and bottom sides of the core rod driven anchor.

[0019] The core rod-driven anchor 1 of the present invention is used when attaching an article to a concrete skeleton W of a building. In this embodiment, a core rod-driven anchor 1 used when attaching a metal fitting M as an article to the concrete skeleton W will be described. Note that hereinafter, the core rod-driven anchor 1 may be simply referred to as anchor 1, and the concrete skeleton W may be simply referred to as skeleton W.

[0020] As shown in FIGS. 1(a) to 1(c), the anchor 1 is mainly composed of a body 10 and a core rod 20 inserted into the body 10.

[0021] As shown in Figures 1(a) to (c) and 2(a) and (b), the body 10 is made of metal and has a generally cylindrical shape with a through hole 11. A threaded shaft portion 12 having a male thread formed on the outer circumferential surface is provided at the top of the body 10. A nut 2 can be screwed onto this threaded shaft portion 12. Reference numeral 5 denotes a washer.

[0022] A plurality of slits 13 (four in this embodiment) are provided in the lower part of the body 10, extending in the vertical direction from the lower end of the body 10. These slits 13 are formed in the radial direction and are evenly spaced in the circumferential direction.

[0023] These slits 13 form a plurality of flat extensions 14 in the lower part of the body 10. More specifically, in this embodiment, four slits 13 are formed at 90-degree intervals in the circumferential direction, dividing this part of the body 10 into four extensions 14. The outer peripheral surface of the lower part of the body 10 has an uneven shape.

[0024] The inner peripheral surface of the lower portion of the body 10 has a stepped shape with a diameter that decreases toward the tip, i.e., downward. More specifically, as shown in FIG. 2(b), the inner peripheral surface of the lower portion of the body 10 is provided with a large diameter section 15, a medium diameter section 16, and a small diameter section 17, from top to bottom. The large diameter section 15 is continuous with the inner peripheral surface of the upper portion of the body 10 (i.e., the through-hole 11) and has the same diameter. Below the small diameter section 17, a protruding section 14a is provided that bulges inward from the lower end of the body 10 (i.e., the lower end of the expansion section 14). Adjacent protruding sections 14a are spaced apart by the width of the slit 13.

[0025] Referring to Figures 1(a)(b), 2(c) and 4(a), the core rod 20 is made of a metal harder than the body 10, and has a head 21 and a rod-shaped portion 22 extending downward from the head 21.

[0026] The head portion 21 is composed of a hexagonal portion 21a that is hexagonal in top view, and a hemispherical bulging portion 21b that bulges out above the hexagonal portion 21a.

[0027] The outer peripheral surface of the hexagonal portion 21a functions as a torque receiving portion that is used when removing the anchor 1, as will be described later.

[0028] As will be described later, the bulging portion 21b (ie, the bulging section) functions as a portion that is struck when the core rod 20 is driven in. The external dimensions of the bulging portion 21b are smaller than the external dimensions of the hexagonal portion 21a.

[0029] The rod-shaped portion 22 has a circular cross section with a diameter slightly smaller than the diameter of the through-hole 11 of the body 10, and its lower end portion gradually tapers downward to form a tip portion 22a as a tapered portion having a so-called spindle shape. The vertical length of the rod-shaped portion 22 is formed slightly longer than the vertical length of the body 10 (see FIG. 4(b)).

[0030] Next, an installation procedure for fixing the metal fitting M to the frame W using the anchor 1 will be described with reference to FIGS.

[0031] As shown in FIG. 3(a), a metal fitting M is placed on a body W, and a pilot hole W1 is formed in the body W through a through-hole M1 of the metal fitting M using a drill 3.

[0032] Next, as shown in FIG. 3(b), the drill 3 is pulled out from the prepared hole W1, and the suction tool 4 is used to suck and remove any debris remaining in the prepared hole W1.

[0033] Next, as shown in Figure 3(c), the anchor 1 is inserted into the through hole M1 and pilot hole W1 of the metal fitting M. In this state, a washer 5 is placed on the threaded shank 12, and the nut 2 is screwed in. At this time, as shown in Figure 4(a), the tip 22a of the core rod 20 is abutted against and supported by a step 15a between the large diameter portion 15 and the medium diameter portion 16 provided on the inner periphery of the body 10. Furthermore, the washer 5 is a disc spring washer whose center portion bulges upward in its natural state.

[0034] Next, as shown in Figures 3(d) and 4(b), the bulging portion 21b of the mandrel 20 is struck with a hammer H to drive it in. When the mandrel 20 is struck, the washer 5 is sandwiched between the nut 2 and the metal fitting M and elastically deforms to become approximately flat, and the tip 22a of the mandrel 20 presses the expansion portion 14 of the body 10 from the inside out, causing the expansion portion 14 to elastically deform and expand. This causes the washer 5 to bite into the inner surface of the pilot hole W1. This maintains the washer 5 in an approximately flat state. Note that Figure 4(b) exaggerates the extent to which the bulging portion 21b is crushed by the impact.

[0035] At this time, as shown in Figure 4(b), friction between the core rod 20 and the expanded portion 14 causes the inner peripheral surface of the expanded portion 14 to be stretched and partially plastically deformed to conform to the outer peripheral surface of the core rod 20 (i.e., the inner peripheral surface of the expanded portion 14 deforms from the shape shown in Figure 4(a) to the shape shown in Figure 4(b)). At the same time, the contact surfaces seize, and the core rod 20 and the expanded portion 14 become integrated at a minute level, resulting in so-called wear adhesion. Adhesion 18 is particularly likely to form at the corners of the step 15a between the large-diameter portion 15 and the medium-diameter portion 16, the corners of the step 16a between the medium-diameter portion 16 and the small-diameter portion 17, and the corners of the step 17a between the small-diameter portion 17 and the protruding portion 14a. In other words, when the core rod 20 is driven into use, the corners of the step portions are scattered axially and adhere to the core rod 20.

[0036] Furthermore, the corners 14b of the protruding portion 14a (see Figures 1(c), 2(b), and 4(a)) slightly bite into the tip portion 22a of the core rod 20, creating scratches 23 that extend in the vertical direction. That is, scratches 23 are created at four locations around the circumference of the tip portion 22a. The depth of the scratches 23 created by the protruding portion 14a biting into the tip portion 22a is 1 / 20 or less of the diameter of the rod-shaped portion 22. This is to achieve a balance between keeping the rotational torque applied to the core rod 20 relatively small when removing the anchor, which will be described later, and ensuring a fixed state due to the bite between the core rod 20 and the body 10 during use.

[0037] Returning to Figure 3(e), if necessary, by tightening the nut 2 around the threaded shank 12, the body 10 can be raised, allowing the expansion portion 14 to be securely engaged with the inner surface of the prepared hole W1. This allows the metal fitting M to be pressed and fixed to the body W.

[0038] Next, a removal procedure for removing the anchor 1 from the skeleton W will be described with reference to Figures 5 and 6. For ease of explanation, the tool R is shown by a two-dot chain line in Figures 5(a) and 5(b).

[0039] As shown in Fig. 5(a), when removing the anchor 1 from the body W, first, the mandrel 20 is rotated about its axis. Specifically, the head 21 of the mandrel 20 has a hexagonal portion 21a, and a tool R such as a hexagonal socket wrench is fitted onto the outer peripheral surface of the hexagonal portion 21a, and the mandrel 20 is rotated. In this way, the hexagonal portion 21a functions as a torque receiving portion that receives rotational torque from the tool R, so the mandrel 20 can be rotated easily.

[0040] As shown in FIG. 5(b) and FIG. 6, the core rod 20 moves upward relative to the body 10 by rotating the core rod 20 around its axis.

[0041] Specifically, as shown in Figure 6(a), a constriction force F acts on the tapered tip portion 22a of the core rod 20 due to a reaction force from the inner surface of the pilot hole W1 and an elastic restoring force of the expansion portion 14 in the inner diameter direction.

[0042] Applying a rotational torque to the core rod 20 around its axis causes the adhered portion 18 to peel off. When the adhered portion 18 peels off, the core rod 20 is lifted upward by the constriction force F and the rotational torque, as shown in Figure 6(b), and the core rod 20 moves upward relative to the body 10. Here, the tip portion 22a of the core rod 20 is spindle-shaped with a diameter that decreases toward the bottom, and the inner circumference of the protruding portion 14a of the body 10 is generally spindle-shaped with a diameter that decreases toward the bottom. This makes it easier for a force f with an upward component to act from the protruding portion 14a of the body 10 to act on the tip portion 22a of the core rod 20. Furthermore, in this embodiment, the elastic restoring force of the washer 5 is also utilized to facilitate the core rod 20's upward relative movement. Specifically, as the core rod 20 moves upward relative to the body 10, the body 10 rises slightly due to the elastic restoring force of the washer 5, and the reaction force from the inner surface of the pilot hole W1 (the area where the expansion portion 14 has not penetrated) acts even stronger on the constriction force F, making it easier for the core rod 20 to move upward relative to the body 10.

[0043] Furthermore, as the core rod 20 rotates, the location of the scratch 23 at the tip 22a (see Figure 4(b)) shifts circumferentially from the corner 14b of the protruding portion 14a, and the circumferentially smooth curved portion of the tip 22a without the scratch 23 comes into contact with the corner 14b of the protruding portion 14a, so that a strong constriction force F is applied along with the rotational torque, making it easier to move the core rod 20 upward.

[0044] In this way, by rotating the core rod 20, the core rod 20 gradually moves upward as shown in Figures 6(a), (b), and (c). As the core rod 20 moves upward, the upward component of the force f becomes smaller, and the core rod 20 moves to the position shown in Figure 6(c) due to the rotation and the force F.

[0045] The internal space of the socket of tool R is sufficiently longer in the vertical direction than the width of the upward movement of core rod 20, so in the state shown in Figure 6(c), head 21 does not abut against the upper surface of the socket, and tool R does not hinder the upward movement of core rod 20.

[0046] 5(c) to 5(f), a jig J that can access the gap between the head 21 of the core rod 20 and the upper end of the body 10 is used to lift the core rod 20 upward and pull it out from the body 10. Since the adhesion portion 18 between the core rod 20 and the body 10 has been peeled off, the core rod 20 can be easily pulled out from the body 10.

[0047] 5(f) and 5(g), a jig J' that can access the gap between the washer 5 and the metal fitting M is used to lift the body 10 upward and pull it out of the pilot hole W1. The elastic restoring force of the expansion portion 14 prevents it from biting into the inner surface of the pilot hole W1, so the body 10 can be easily pulled out of the pilot hole W1.

[0048] This allows the metal fitting M to be removed from the body W without leaving the anchor 1 in the prepared hole W1, as shown in FIG. 5(h).

[0049] Next, the load acting when the core rod 20 is pulled out will be described with reference to FIG.

[0050] As shown by the dashed line in Figure 7, a conventional anchor experiences a maximum tensile force of 3.8 kN when the mandrel is pulled out. This is because the mandrel is attached to the expansion section of the body, and the reaction force from the inner surface of the pilot hole and the elastic restoring force of the expansion section (i.e., the constriction force) act on the mandrel.

[0051] On the other hand, as shown by the solid line in Figure 7, the anchor 1 of this embodiment experiences a maximum tensile force of approximately 1.4 kN when the core rod 20 is pulled out, which is less than half that of a conventional anchor. This is because the core rod 20 is rotated around its axis to separate the adhered portion 18 and lift the core rod 20 from the body 10, that is, the core rod 20 is pulled out in a state where the reaction force from the inner surface of the pilot hole W1 and the elastic restoring force of the expansion portion 14 (i.e., the constriction force F) are not acting on the core rod 20.

[0052] As explained above, the mandrel 20 can be easily removed with a small force by engaging a tool with the outer peripheral surface of the hexagonal portion 21a of the mandrel 20 and applying a rotational torque to peel the mandrel 20 from the body 10. Furthermore, since the body 10 from which the mandrel 20 has been extracted can be pulled out of the body W with a small force, the work of removing the anchor 1 is simple. Furthermore, there is no need to cut it with a grinder or the like, and the anchor 1 will not be left behind in the body W.

[0053] Furthermore, when the core rod 20 is driven into use, the core rod 20 is subjected to a constriction force F due to the reaction force from the inner surface of the pilot hole W1 and the elastic return force of the expansion portion 14 in the inner diameter direction. Therefore, by applying a rotational torque to the core rod 20, it is subjected to the constriction force F and is prone to floating in the removal direction.

[0054] Furthermore, since the constriction force F acts on the tapered tip portion 22a of the core rod 20, applying a rotational torque to the core rod 20 causes it to be lifted upward by the expansion portion 14. In other words, the core rod 20 is likely to float in the removal direction.

[0055] Furthermore, the inner periphery of the expansion portion 14 is stepped, with the diameter decreasing toward the tip, and when the core rod 20 is driven into use, the corners of step portions 15a, 16a, and 17a become adhesion portions 18 that bite into the core rod 20. In other words, since the adhesion portions 18 are not formed long in the axial direction but are scattered in the axial direction, the adhesion portions 18 can be peeled off by rotating the core rod 20 with a relatively small rotational torque.

[0056] Furthermore, since the portion of the body 10 that is gripped by the core rod 20 faces the portion that is not gripped by the core rod 20, a small gap is created between the core rod 20 and the inner circumference of the body 10, making it easier to eliminate the grip between the body 10 and the core rod 20.

[0057] Furthermore, the outer peripheral surface of the hexagonal portion 21a of the core rod 20 is flat, specifically consisting of six flat surfaces, so that a commonly used tool such as a hexagonal socket wrench can be used, and since it is only necessary to apply a lateral force to the hexagonal portion 21a, the core rod 20 is not hindered from floating up due to the constriction force F, and the core rod 20 is easy to pull out.

[0058] In addition, the head 21 of the core rod 20 has a bulging portion 21b above the hexagonal portion 21a serving as a torque receiving portion, and this bulging portion 21b is struck with a hammer H to drive the core rod 20, thereby preventing the hexagonal portion 21a from being deformed by the strike and ensuring that a rotational torque is applied to the hexagonal portion 21a.

[0059] Furthermore, since the outer dimensions of the bulging portion 21b are smaller than the outer dimensions of the hexagonal portion 21a, even if the bulging portion 21b is crushed by an impact, the crushing is unlikely to spread to the outer peripheral surface of the hexagonal portion 21a, and the function of the hexagonal portion 21a as a torque receiving portion is unlikely to be impaired.

[0060] Furthermore, since the core rod 20 is made of a metal harder than the body 10, the adhesion portion 18 is easily peeled off by applying a rotational torque.

[0061] In this embodiment, the bulging portion 21b of the head 21 of the core rod 20 has a hemispherical shape, but this is not limited to this and may be a polyhedron such as a prism, and can be freely modified.

[0062] The shape of the head of the core rod can be freely changed and may be as follows:

[0063] 8(a), the head 121 of the core rod 120 of the first modification is hexagonal in top view. That is, the head 121 does not have a bulge. The outer peripheral surface of the head 121 serves as a torque receiving portion.

[0064] 8(b), the head 221 of the core rod 220 of Modification 2 has a rectangular shape when viewed from above. The outer peripheral surface of this head 221 serves as a torque receiving portion. In this manner, the outer peripheral surface of the head only needs to have an engaging surface that can be engaged with a conventional tool such as a wrench or pliers.

[0065] As shown in Figure 8(c) , the head 321 of the core rod 320 of Modification 3 has a circular shape when viewed from above. A through-hole 321a is formed in the head 321, penetrating in the left-right direction. A rod 6 can be inserted into this through-hole 321a. With the rod 6 inserted into the through-hole 321a, both ends of the rod 6 are held with a jig or the like, and a rotational torque is applied, thereby rotating the core rod 320.

[0066] Instead of the through-hole 321a, a portion to be acted upon, such as a recess or a protrusion, may be provided on the side surface of the head, and a jig may be engaged with this portion to apply a rotational torque.

[0067] 8(d), head 421 of core rod 420 of Modification 4 has a circular shape when viewed from above. A recessed hole 421a is formed on the top surface of head 421, into which a Phillips head screwdriver can be engaged.

[0068] This recessed hole 421a can be accessed from above with a Phillips head screwdriver, which is a commonly used tool, and rotational torque can be applied, resulting in excellent operability.

[0069] 8(e), a recessed hole 521a into which a hexagonal screwdriver can be engaged is formed on the upper surface of the head 521 of the core rod 520 of Modification 5. This recessed hole 521a can be accessed from above with a hexagonal screwdriver, which is a commonly used tool, and rotational torque can be applied, resulting in excellent operability.

[0070] As shown in Fig. 8(f), the head 921 of the core rod 920 of Modification 6 has a hexagonal shape when viewed from above. A recessed hole 921a is formed in the top surface of the head 921. As such, the shape of the recessed hole 921a is not limited to a shape that allows a tool to be engaged. For example, the recessed hole 921a may serve as a clearance to prevent a part of a tool that engages with the outer circumferential surface of the head 921 from interfering with the core rod 920.

[0071] The shape of the recessed hole is not limited to a shape that can be engaged with a Phillips head screwdriver or a hexagonal head screwdriver, and can be freely changed. Also, instead of a recessed hole, a protrusion or other actuated portion may be provided at an eccentric position on the top surface of the head, and a jig may be engaged with this actuated portion to apply rotational torque.

[0072] 9, the outer peripheral surface of the hexagonal portion 721a of the mandrel 720 of Modification 6 is inclined by an angle α so that its outer dimension tapers downward. By applying a rotational torque to the mandrel 720 with a tool R', such as a hexagonal wrench, a force f' having an upward component acts on the outer peripheral surface of the hexagonal portion 721a from the tool R', making it easy to lift the mandrel 720 upward. It goes without saying that the mandrel 720 can also be easily lifted upward using the tool R, such as the hexagonal socket wrench described above.

[0073] 10, in the hexagonal portion 821a of the core rod 820 of the seventh modified example, ridge lines 821c between adjacent flat surfaces that make up the outer circumferential surface thereof extend downward at an angle β inclined in the rotation direction of the tool R. According to this, by applying a rotational torque to the core rod 820 with the tool R, a force f'' having an upward component acts from the tool R on the outer circumferential surface of the hexagonal portion 821a, and therefore the core rod 820 can be easily lifted upward.

[0074] 11(a), the anchor 61 of the eighth modification has four slits 613 extending in the up-down direction provided in the circumferential direction at approximately the center in the up-down direction of the body 610. In other words, four extension portions 614 are formed in the circumferential direction at approximately the center in the up-down direction of the body 610.

[0075] As shown in FIG. 11(b), when the core rod 620 is driven, the tip 622a of the core rod 620 elastically deforms at the approximately central upper and lower portions of each expansion portion 614 of the body 610, expands outward, and bites into the inner surface of the pilot hole W1.

[0076] As in the above embodiment, by pulling out the core rod 620 from the body 610, the expansion portion 614 elastically recovers, eliminating the jamming of the expansion portion 614 into the inner surface of the pilot hole W1, so that the body 610 can be easily pulled out from the pilot hole W1.

[0077] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes modifications and additions that do not deviate from the gist of the present invention.

[0078] For example, in the above embodiment, the tip portion 22a of the core rod 20 has a smooth tapered shape in which the diameter gradually decreases toward the tip, but the tapered portion may have a stepped shape in which the diameter decreases toward the tip. Also, the core rod may not have a tapered portion and may extend in the axial direction with a constant thickness.

[0079] In the above embodiment, the rod-shaped portion 22 has been illustrated as having a circular cross section, but this is not limitative and the rod-shaped portion 22 may have a rectangular cross section, other polygonal cross section, or an elliptical cross section.

[0080] Furthermore, although the anchor 1 in the above embodiment is exemplified as being configured to attach the metal fitting M to the concrete skeleton W, the item attached to the concrete skeleton can be freely changed. For example, the anchor may be used to directly attach items such as various devices, piping, light ceilings, ducts, etc. to the concrete skeleton.

[0081] Furthermore, in the above embodiment, the core rod 20 is made of a harder metal than the body 10, but the core rod may be made of the same metal or a softer metal than the body.

[0082] Furthermore, the body 10 and the core rod 20 are not limited to being made of metal, but may be made of resin or the like.

[0083] Furthermore, in the above embodiment, the core rod 20 is driven in by the hammer H, but the core rod may be driven in by using a dedicated driving tool or machine.

[0084] In addition, in the above embodiment, the inner circumference of the expansion section 14 is shaped like a step, with the diameter decreasing downward through the large diameter section 15, the medium diameter section 16, and the small diameter section 17, but the number of steps and the diameter of each step may be freely changed.

[0085] In the above embodiment, the fixed body is exemplified as a concrete body W, but the fixed body is not limited to this. For example, the fixed body may be made of gypsum, wood, metal, synthetic resin, or the like.

[0086] Furthermore, it goes without saying that if the core rod is not rotated, the anchor has the same load-bearing capacity as a conventional core rod-driven anchor. [Explanation of symbols]

[0087] 1 Core rod driven anchor 2 nuts 10 Body 13 Slit 14 Extension 15a~17a Stepped section 18 Adhesion part 20 core rod 21 Head 21a Hexagonal part (torque receiving part) 21b Bulging area (bulging part) 22 Rod-shaped part 22a Tip part (reduced diameter part) 23 Scar F constriction force M Metal fittings (items) W Concrete frame (fixed body) W1 pilot hole

Claims

1. A core rod driving type anchor in which a core rod is driven into a center hole of a body inserted into a pilot hole of a fixed body, thereby expanding an expansion portion having a slit formed in the body and fixing the anchor to the fixed body, A core rod-driven anchor characterized in that the head of the core rod is formed with a torque receiving portion capable of receiving a rotational torque from the outside.

2. 2. The core rod-driven anchor according to claim 1, wherein, in a state of use, the core rod receives an elastic restoring force in a narrowing direction from the expansion portion.

3. 3. The core rod driven anchor according to claim 2, wherein the core rod has a tapered portion whose diameter gradually decreases, and the tapered portion is constricted by the expanded portion.

4. 2. The core rod-driven anchor according to claim 1, wherein the inner periphery of the expanded portion has a stepped shape in which the diameter decreases toward the tip.

5. 2. The core rod-driven anchor according to claim 1, wherein the torque receiving portion has a flat side portion of the head portion.

6. 6. The core rod-driven anchor according to claim 5, wherein the side of the head is hexagonal in top view.

7. 2. The core rod-driven anchor according to claim 1, wherein a bulge is provided above the torque receiving portion.

8. 2. The core rod-driven anchor according to claim 1, wherein the torque receiving portion is a recessed hole provided at the top of the head portion.

9. A method for removing a core-rod-driving type anchor fixed to a fixed body, in which a core rod is driven into a central hole of a body inserted into a pilot hole of a fixed body, so that the core rod receives an elastic restoring force in a narrowing direction from an expanded portion of the body where a slit is formed, and the expanded portion expands, A method for removing a core rod-driven anchor, comprising the step of applying a rotational torque to the head of the core rod from the outside to rotate the core rod.

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