A self-undercutting anchor

Abstract

The application discloses a self-cutting bottom type anchor bolt, which is composed of a conical head anchor rod and a sleeve, a washer and a nut which are sequentially sleeved on the anchor rod, the bottom of the anchor rod is conical or trumpet-shaped, the middle part is a non-threaded section, and the top is a threaded section; the sleeve is a hollow cylinder, the top end of the sleeve is provided with a clamping groove matched with an installation tool, and the bottom end is provided with a bottom cutting tool bit; a structure for preventing the sleeve from falling off is arranged in the clamping groove, which is formed by locally stamping the inner wall of the clamping groove, forming a pit on the outer wall of the sleeve in the clamping groove and forming a convex point on the inner wall, the inner diameter of the sleeve at the convex point is smaller than the diameter of the threaded section of the conical head anchor rod and larger than the diameter of the non-threaded section; the bottom cutting tool bit is uniformly divided into 2-8 tool bits by 2-8 parallel slits arranged in the axial direction of the sleeve, and the top of the tool bits is provided with a cutting edge made of hard alloy or diamond material at intervals. The self-cutting bottom anchor bolt has the advantages of good hole forming quality, high hole forming efficiency and good bearing performance.

Description

Technical Field

[0001] This invention relates to the field of post-anchoring technology for concrete structures, specifically to a self-cutting mechanical anchor bolt with a structure to prevent anchor bolt sleeve from falling off and a novel bottom-cutting head design. Background Technology

[0002] Self-cutting mechanical anchors are a type of post-anchoring technology for concrete structures. The principle is to place the self-cutting mechanical anchor in a straight hole in the concrete, and then rotate or tap the anchor sleeve with a special installation tool. The cutting head at the front end of the sleeve cuts the straight hole in the concrete, forming a conical hole at the bottom of the straight hole, thus anchoring the anchor in the concrete. It has the advantages of simple installation and low construction cost, and is widely used in construction projects.

[0003] Existing self-cutting mechanical anchors use a method of punching holes in the sleeve body to prevent the sleeve and anchor rod from detaching during transportation and initial installation on the overhead surface. However, punching holes in the sleeve body weakens the local strength and overall rigidity of the sleeve, affecting the cutting ability of the cutting head on the concrete. Furthermore, self-cutting mechanical anchors form a conical hole by cutting concrete with a cutting head at the front end of the sleeve. Under the action of the conical head of the anchor rod, the cutting head opens radially and forms a mechanical locking key with the conical hole. The quality of the conical hole is crucial to the anchor's load-bearing capacity. Existing self-cutting mechanical anchors use the sleeve's own geometric cutting edge or two symmetrically welded carbide cutting edges for the cutting head, resulting in low cutting efficiency and poor conical hole formation, thus leading to a decrease in the anchor's load-bearing capacity and an increase in displacement. Summary of the Invention

[0004] This invention addresses the shortcomings of existing self-cutting mechanical anchors by proposing a self-cutting mechanical anchor with a sleeve-preventing structure and a novel cutting head, which has the advantages of good hole-forming quality, high hole-forming efficiency, and good load-bearing performance.

[0005] This invention is achieved through the following technical solution:

[0006] A self-cutting bottom anchor bolt, comprising a tapered head anchor bolt and a sleeve, washer, and nut sequentially fitted onto the tapered head anchor bolt, characterized in that:

[0007] The bottom of the cone-head anchor bolt is cone-shaped or trumpet-shaped, the middle section is unthreaded, and the top section is threaded.

[0008] The sleeve is a hollow cylinder with a groove at the top that matches the installation tool and a bottom-cutting blade at the bottom. The groove has a structure to prevent the sleeve from falling off. This structure is achieved by locally stamping the inner wall of the groove, creating a pit on the outer wall of the sleeve and a protrusion on the inner wall. The inner diameter of the sleeve at the protrusion is smaller than the diameter of the threaded section of the tapered head anchor rod but larger than the diameter of the unthreaded section. The bottom-cutting blade is divided into 2 to 8 blades by 2 to 8 parallel slits along the axis of the sleeve. The blades have cutting edges made of carbide or diamond at intervals on their tops.

[0009] The self-cutting anchor bolt of the present invention has at least one circumferentially arranged circumferential blade on the outer wall surface of the cutting head sleeve.

[0010] Furthermore, the cutting edge protrudes axially from the blade end face by 0.1–5 mm and radially from the outer surface of the blade by 0.1–2 mm. The cutting edge is positioned centrally, offset, or obliquely at -60° to 60° relative to the blade centerline. A centrally or offset arrangement relative to the blade centerline is preferred.

[0011] Furthermore, the outer diameter of the sleeve is smaller than the diameter of the concrete installation hole, and the inner diameter is larger than the diameter of the threaded section of the tapered head screw; a deformation groove with an annular groove structure is provided on the rear surface of the bottom cutting head of the sleeve along the circumference, and the sleeve wall thickness in the deformation groove area gradually decreases along the axis from the slot to the cutting head; a non-metallic support ring is installed in the deformation groove.

[0012] Furthermore, the structure to prevent the sleeve from falling off is to form pits and protrusions by partially stamping one or both sides of the slot; the pits and protrusions are circular, semi-circular or rectangular in shape.

[0013] The self-cutting bottom anchor of the present invention has the following advantages compared with the prior art:

[0014] Existing self-cutting bottom anchors use a sleeve body punching method to prevent separation between the tapered head anchor rod and the sleeve. However, the punching weakens the local strength and overall rigidity of the sleeve, resulting in uneven load transmission from the sleeve body to the blades during anchor installation. This causes inconsistent blade opening, affecting the quality of the tapered hole. The novel anti-sleeve detachment structure of this invention is located in the groove at the top of the sleeve, without compromising the overall rigidity of the sleeve. During anchor installation, the load transmitted from the sleeve to the blades is more even, and the blade opening is more consistent, thus improving the quality of the tapered hole.

[0015] The novel bottom-cutting cutter head of the present invention has cutting edges made of cemented carbide or diamond arranged at intervals on its blades. Compared with the existing structure of two symmetrically arranged cutting edges in self-cutting anchors, it can improve the cutting efficiency of self-cutting anchors. The cutting edges are offset or inclined at the center line of the blades, which can provide additional support force when the blades cut concrete, effectively solving the problem of blade breakage or blade chipping caused by insufficient support force when cutting concrete in existing self-cutting anchors.

[0016] The novel cutting head of this invention features one or more circumferential cutting edges, which provide additional cutting action when the cutting edge cuts concrete. When the anchor bolt is under stress, the circumferential cutting edges embed into the concrete hole wall, effectively preventing the self-cutting anchor bolt from slipping relative to the concrete hole and providing additional load-bearing capacity.

[0017] Its working principle is as follows:

[0018] The working principle is as follows: The anchor bolt is inserted into a pre-drilled straight concrete hole. Using a suitable impact drill and installation tool, one end of the installation tool is connected to the impact drill, and the other end matches the groove at the top of the sleeve. The impact drill drives the sleeve to rotate and advance towards the bottom of the concrete hole through a special installation tool. During this process, the bottom cutting head at the bottom of the sleeve opens radially, and the cutting edge and circumferential edge of the bottom cutting head simultaneously cut the concrete hole wall. As the sleeve advances and opens radially, the bottom cutting head gradually cuts and expands the bottom of the straight concrete hole into a tapered hole. The radially opened bottom cutting head and the tapered hole at the bottom of the concrete hole form a mechanical locking effect. The circumferential edges distributed on the cutting head further embed into the concrete hole wall and form a mechanical locking effect with the concrete, enhancing the anchoring effect. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the self-cutting bottom anchor bolt of the present invention;

[0020] Figure 2 This is a schematic diagram of the self-cutting bottom anchor bolt with a conical head.

[0021] Figure 3 This is a schematic diagram of the self-cutting bottom anchor sleeve of the present invention;

[0022] Figure 4 This is a schematic diagram of the self-cutting bottom anchor bolt anti-loosening structure of the present invention;

[0023] Figure 5 This is a schematic diagram of the self-cutting bottom anchor bolt cutting head with the blade positioned in the middle;

[0024] Figure 6 This is a schematic diagram of the offset blade of the self-cutting bottom anchor head of the present invention;

[0025] Figure 7 This is a schematic diagram of the inclined cutting edge of the self-cutting bottom anchor head of the present invention;

[0026] Figure 8 A schematic diagram of an existing self-cutting mechanical anchor bolt.

[0027] In the diagram, 1—conical head anchor bolt, 2—sleeve, 3—support ring, 4—blade;

[0028] 1.1—Threaded section, 1.2—Unthreaded section, 1.3—Conical head section; 2.1—Slot, 2.2—Dent, 2.3—Installation mark line, 2.4—Deformation groove, 2.5—Bottom cutting head, 2.6—Circular blade, 2.7—Slit, 2.8—Blade. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments. These specific embodiments are further explanations of the principles of the present invention and are not intended to limit the present invention in any way. Any technology that is the same as or similar to the present invention does not exceed the scope of protection of the present invention.

[0030] Refer to the attached diagram.

[0031] As shown in the figure, the self-cutting bottom anchor bolt of the present invention includes a conical head anchor rod 1, a sleeve 2, a support ring 3, and a blade 4.

[0032] The tapered head anchor bolt 1 consists of a threaded section 1.1, an unthreaded section 1.2, and a tapered head section 1.3.

[0033] The sleeve 2 consists of a groove 2.1, a recess 2.2 to prevent the sleeve from falling off, an installation marking line 2.3, a deformation groove 2.4, a bottom cutting head 2.5, a circumferential blade 2.6, and a cutting edge 4. Specifically, a recess 2.2 is formed on the outer wall of the sleeve and a protrusion is formed on the inner wall at one or two locations within the groove 2.1 using a stamping method. The inner diameter of the sleeve at the protrusion is smaller than the diameter of the threaded section 1.1 of the tapered head anchor rod and larger than the diameter of the unthreaded section 1.2.

[0034] The wall thickness of the sleeve 2 in the deformation groove 2.4 area gradually decreases along the axis from the slot towards the cutter head, which makes it easier for the bottom cutting cutter head 2.5 to open during the bottom cutting process.

[0035] The undercutting head 2.5 is divided into several blades 2.8 by an axial slit 2.7 along the sleeve axis. Cutting edges 4 are spaced axially on the end faces of the blades 2.8. The cutting edges 4 are made of cemented carbide or diamond. The cutting edges 4 are fixed to the blades 2.8 by welding, threading, or pinning. The cutting edges 4 protrude 0.1–5 mm axially relative to the end face of the blade 2.8 and 0.1–2 mm radially relative to the surface of the blade 2.8. The cutting edges 4 are positioned centered, offset, or at -60° to 60° relative to the blade centerline. The three arrangements—centered, offset, or at -60° to 60° relative to the blade centerline—are described in detail below.

[0036] like Figure 5As shown, the cutting edge 4 is centered relative to the center line of the blade 2.8, dividing the blade 2.8 into two parts of equal width along its circumference. When the cutting edge 4 cuts concrete, the two parts of the blade 2.8 provided the same support force. Its advantage is that it does not restrict the cutting rotation direction of the cutting edge 4, and can rotate clockwise or counterclockwise to cut concrete.

[0037] like Figure 6 As shown, the cutting edge 4 is offset relative to the center line of the blade 2.8, dividing the blade 2.8 into two parts of unequal width along its circumference. The wider part provides greater support force when the cutting edge 4 cuts concrete than the narrower part. By arranging the relative position of the cutting edge 4 offset to the center of the blade 2.8 according to the cutting rotation direction of the cutting edge 4, the cutting edge 4 can obtain greater support force when cutting concrete, which can effectively solve the problem of blade breakage or blade chipping caused by insufficient support force when the cutting edge of the existing self-cutting bottom anchor bolt is cutting concrete.

[0038] like Figure 7 As shown, the cutting edge 4 is inclined at -60° to 60° relative to the center line of the blade 2.8. The inclined arrangement increases the contact area between the cutting edge 4 and the blade 2.8. When the cutting edge 4 and the blade 2.8 are welded together, the weld length is increased, which can improve the bonding strength between the cutting edge 4 and the blade 2.8. In addition, when the cutting edge is inclined, the contact area between the cutting surface of the cutting edge and the concrete is increased, which can effectively improve the cutting efficiency.

[0039] The support ring 3 is installed inside the deformation groove 2.4. The support ring 3 is made of non-metallic material. Its outer diameter is smaller than the maximum outer diameter of the sleeve 2, its inner diameter is larger than the maximum outer diameter of the deformation groove 2.4, and its thickness is smaller than the width of the deformation groove 2.4. The function of the support ring 3 is to limit the opening degree of the bottom cutting head 2.5 to prevent the bottom cutting head from being damaged due to excessive opening caused by improper installation and operation. At the same time, the support ring 3 can prevent large concrete particles from entering the deformation groove 2.4 during the bottom cutting process, and prevent the bottom cutting head 2.5 from opening unevenly due to concrete particles entering the deformation groove 2.4.

[0040] The circumferential cutting edge 2.6 is located between the circumferential groove 2.4 and the cutting edge 4, and is evenly distributed on each blade 2.8. There are one or more such blades, and their radial protrusions are 0.1 to 2 mm beyond the surface of the blade 2.8.

Claims

1. A self-cutting bottom anchor bolt, comprising a tapered head anchor bolt and a sleeve, washer, and nut sequentially fitted onto the tapered head anchor bolt, characterized in that: The bottom of the cone-head anchor bolt is cone-shaped or trumpet-shaped, the middle section is unthreaded, and the top section is threaded. The sleeve is a hollow cylinder. The outer diameter of the sleeve is smaller than the diameter of the concrete mounting hole, and the inner diameter is larger than the diameter of the threaded section of the tapered head screw. The bottom end of the sleeve has a deformation groove with a ring groove structure on the rear surface of the cutting head. The sleeve wall thickness in the deformation groove area gradually decreases from the slot to the cutting head along the axis. A non-metallic support ring is installed in the deformation groove. Its outer diameter is smaller than the maximum outer diameter of the sleeve, its inner diameter is larger than the maximum outer diameter of the deformation groove, and its thickness is smaller than the width of the deformation groove. The function of the support ring is to limit the opening degree of the cutting head to prevent the cutting head from being damaged due to excessive opening caused by improper installation and operation. At the same time, the support ring can prevent large concrete particles from entering the deformation groove during the cutting process, and prevent the cutting head from opening unevenly due to concrete particles entering the deformation groove. The top of the sleeve is provided with a groove that matches the installation tool, and the bottom is provided with a bottom cutting head; the groove is provided with a structure to prevent the sleeve from falling off. The structure to prevent the sleeve from falling off is formed by locally punching the inner wall of the sleeve, creating a pit on the outer wall of the sleeve and a protrusion on the inner wall. The inner diameter of the sleeve at the protrusion is smaller than the diameter of the threaded section of the tapered head anchor rod but larger than the diameter of the unthreaded section. The structure to prevent the sleeve from falling off is located in the groove at the top of the sleeve and will not damage the overall rigidity of the sleeve. The bottom-cutting head is evenly divided into 2 to 8 blades by 2 to 8 parallel slits set along the axis of the sleeve. The blades are spaced apart with cutting edges made of cemented carbide or diamond. The cutting edges are centrally located, offset, or obliquely arranged at -60° to 60° relative to the centerline of the blade, providing additional support when the blades cut concrete. This effectively solves the problem of blade breakage or chipping caused by insufficient support when the blades of existing self-cutting anchor bolts cut concrete.

2. The self-cutting bottom anchor bolt according to claim 1, characterized in that: The outer wall surface of the bottom cutting blade sleeve is provided with at least one circumferentially arranged annular blade.

3. The self-cutting bottom anchor bolt according to claim 2, characterized in that: The cutting edge protrudes axially from the end face of the blade by 0.1–5 mm and radially from the outer surface of the blade by 0.1–2 mm.

4. The self-cutting bottom anchor bolt according to claim 2, characterized in that: The structure to prevent the sleeve from falling off is formed by locally stamping one or both sides of the slot to create pits and bumps; the pits and bumps are circular, semi-circular or rectangular in shape.

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