Expansion bolt

Abstract

The invention belongs to the technical field of expansion bolts, and particularly relates to an expansion bolt. Comprising a bolt, an expansion sleeve and an extrusion sleeve, a plurality of movable columns are arranged at the bottom of the side wall of the expansion sleeve in a surrounding mode and communicated with the inner side and the outer side of the expansion sleeve, the diameter of the movable columns is larger than the wall thickness of the side wall of the expansion sleeve, the extrusion sleeve is arranged in the expansion sleeve in a sliding mode, and the bolt is divided into a large column section and a small column section; threads are arranged on the large column section and the small column section respectively, the threads of the large column section are connected with the threads on the top of the inner side wall of the expansion sleeve, and the extrusion sleeve moves inwards synchronously along with the bolt moving towards the interior of the expansion sleeve. The outer side wall of the extrusion casing pipe abuts against the movable columns and pushes the movable columns to move towards the outside of the expansion casing pipe, the movable columns reset along with pulling out of the extrusion casing pipe, threads are arranged on the inner wall of the extrusion casing pipe, and the inner wall of the extrusion casing pipe is in threaded connection with the small column section; the device can be conveniently disassembled and reused.

Description

Technical Field

[0001] The invention belongs to the technical field of expansion bolts, and in particular relates to an expansion bolt. Background Art

[0002] Expansion bolts are fasteners used to fix pipe supports / hangers / brackets or equipment to walls, floors, and columns. Expansion bolts usually consist of the following parts: countersunk bolts: mainly for connection and fixing, with specific thread and taper design; expansion sleeves: cooperate with bolts, when the bolts are tightened, the expansion sleeves will expand outwards and form a close contact with the fixed body; flat washers and spring washers: used to increase the stability of the connection part and prevent loosening; hexagonal nuts: used to tighten the bolts to expand the expansion sleeves and fix them on the fixed body. These components work together to achieve the fastening and fixing functions through a specific mechanism. The working principle of expansion bolts is mainly based on friction grip. When the bolt is screwed into a pre-drilled hole, the tapered part of the bolt forces the expansion sleeve to expand outwards and form a close contact with the hole wall. As the nut is further tightened, the bolt continues to stretch outwards, and the expansion sleeve fits more closely to the hole wall, thereby generating a strong friction grip, firmly connecting the bolt and the fixed object together.

[0003] When the expansion sleeve is made of soft materials such as plastic, it is difficult to use for a long time and is not suitable for high load conditions. When the expansion sleeve is made of hard materials such as metal, after the metal expansion sleeve is expanded by the enlarged head of the bolt on one side of the mounting hole, if the expansion bolt needs to be removed, the expansion sleeve is difficult to remove due to the expansion and deformation, or the structure around the mounting hole is damaged after forced removal, which brings inconvenience in use; at the same time, the expansion sleeve is difficult to reuse after deformation. Moreover, the bolt part and the expansion sleeve part of the general expansion bolt need to be put into the mounting hole at the same time, and then the bolt part is rotated and pulled out. The expansion sleeve is expanded during the process of pulling out the expansion sleeve from the enlarged head of the bolt inside the mounting hole. Therefore, the bolt needs to be pulled out of the mounting hole, resulting in the hollowness of the expansion sleeve in the mounting hole, and then the bearing capacity decreases. When used for heavy loads, the expansion bolt will form a lever inside and outside the mounting hole, and a fulcrum will be formed at the bottom of the mounting hole outlet, which is easy to cause excessive force on the part of the expansion bolt mounting hole.

[0004] Therefore, in order to solve the above problems existing in the prior art, an expansion bolt is proposed. Summary of the invention

[0005] In order to solve the problem in the prior art that the expansion sleeve is difficult to remove and reuse due to expansion and deformation after installation, the present invention provides an expansion bolt.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] An expansion bolt of the present invention comprises a bolt, an expansion sleeve and an extrusion sleeve, wherein a plurality of movable columns are arranged around the bottom of the side wall of the expansion sleeve and connect the inner and outer sides of the expansion sleeve, the diameters of the plurality of movable columns are greater than the thickness of the side wall of the expansion sleeve, the extrusion sleeve is slidably arranged in the expansion sleeve, the bolt is divided into a large column section and a small column section, and the large column section and the small column section are respectively provided with threads, the threads of the large column section are connected with the threads at the top of the inner wall of the expansion sleeve, the extrusion sleeve moves inward synchronously with the movement of the bolt into the expansion sleeve, the outer wall of the extrusion sleeve abuts against the plurality of movable columns and pushes the plurality of movable columns to move outside the expansion sleeve, and the movable columns are reset when the extrusion sleeve is pulled out.

[0008] Furthermore, the inner wall of the extrusion sleeve is provided with threads, and the inner wall of the extrusion sleeve is threadedly connected to the small column section.

[0009] Furthermore, the diameter of the outer side wall of the extrusion sleeve gradually increases from the bottom to the top of the expansion sleeve.

[0010] Furthermore, the diameters of the plurality of movable columns gradually decrease from the bottom to the top of the expansion casing.

[0011] Furthermore, the inclination angle of the outer wall of the extrusion sleeve is one to two times the inclination angle of the plurality of movable columns. The plurality of movable columns are squeezed by the extrusion sleeve to form an enlarged head outside the expansion sleeve with two sides parallel or gradually increasing in inclination from the top to the bottom of the expansion sleeve.

[0012] Furthermore, a plurality of movable cavities are arranged around the wall of the expansion casing, each of the movable cavities corresponds to a movable column, and the plurality of movable cavities are used to limit the position of the movable columns on the wall of the expansion casing.

[0013] Furthermore, both end surfaces of the plurality of movable columns are hemispherical surfaces, and the contact surfaces between the extrusion sleeve and the plurality of movable columns are provided with rounded corners.

[0014] Furthermore, the outer wall of the extrusion sleeve is provided with arc grooves corresponding to the number of the movable columns, and the arc grooves are arranged along the axial direction of the extrusion sleeve, the inclination angle of the outer wall of the extrusion sleeve is set in the arc groove, and the arc grooves are slidably abutted against the movable columns in a one-to-one correspondence to prevent the extrusion sleeve from rotating.

[0015] Furthermore, a rectangular section is provided at the top of the bolt, the rectangular section has four faces in the axial direction, and two faces are parallel to each other, and the rectangular section is used to tighten the bolt by a tool.

[0016] Furthermore, the shoulder between the large column section and the small column section is an inclined surface.

[0017] The beneficial effects of the present invention are:

[0018] (1) Sliding the extrusion sleeve into the expansion sleeve, and then preliminarily connecting the thread on the large column section of the bolt with the thread on the inner wall of the expansion sleeve, and then putting the entire expansion bolt into the installation hole of the wall or other required objects, and then gradually tightening the bolt. When the bolt is gradually screwed into the expansion sleeve, the extrusion sleeve will apply thrust to the several movable columns, so that part of the side wall area of ​​the movable column extends out of the expansion sleeve, so that the overall diameter of the expansion sleeve is increased, forming an extrusion force on the installation hole and completing the installation. When the expansion bolt needs to be removed, it is only necessary to screw the bolt out of the expansion sleeve, and then remove the extrusion sleeve to loosen the several movable columns and then easily remove it. The expansion bolt after removal can also be reused;

[0019] (2) By first installing the expansion sleeve in the mounting hole and then gradually screwing the bolt in, on the basis of the same overall length of the expansion bolt, the bolt portion of the expansion bolt in the present invention can be effectively inserted into the mounting hole and the expansion sleeve for a longer length, thereby improving the bearing capacity of the expansion bolt while preventing the bolt from forming a large lever force with the external bolt due to insufficient depth in the mounting hole;

[0020] (3) When installing the expansion bolt, the bolt is connected to the threads on the inner wall of the extrusion sleeve and the expansion sleeve respectively, and then the bolt is gradually tightened. As the bolt is tightened and the extrusion sleeve gradually penetrates to the bottom of the expansion sleeve, the screwing in of the bolt not only drives the bolt to gradually extend into the expansion sleeve, but also, because the thread spacing on the large column section and the expansion sleeve is larger than the thread spacing on the small column section and the extrusion sleeve, the distance that the large column section enters into the expansion sleeve after one rotation is larger than the distance that the small column section enters into the extrusion sleeve. Therefore, the rotation of the bolt and the action of extending into the expansion sleeve will also drive the extrusion sleeve to gradually penetrate into the bottom of the expansion sleeve; and when the expansion bolt needs to be removed, the extrusion sleeve will be removed along with the screwing out of the bolt. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0022] Figure 1 This is a schematic diagram of the internal structure of the expansion bolt of the present invention;

[0023] Figure 2 It is a structural schematic diagram of the threaded connection between the bolt and the expansion casing of the present invention;

[0024] Figure 3 It is a structural schematic diagram of the bolt and the extrusion sleeve of the present invention inserted into the bottom of the expansion sleeve;

[0025] Figure 4This is a schematic diagram of the external structure of the expansion bolt of the present invention;

[0026] Figure 5 It is a structural schematic diagram of the expansion bolt of the present invention installed in the installation hole.

[0027] Explanation of the reference numerals: 1. expansion sleeve; 2. bolt; 21. small column section; 22. large column section; 23. rectangular section; 3. movable column; 4. extrusion sleeve. DETAILED DESCRIPTION

[0028] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0029] like Figure 1-5 As shown, an expansion bolt of the present invention comprises a bolt 2, an expansion sleeve 1 and an extrusion sleeve 4, a plurality of movable columns 3 are arranged around the bottom of the side wall of the expansion sleeve 1 and are connected to the inner and outer sides of the expansion sleeve 1, the diameters of the plurality of movable columns 3 are larger than the thickness of the side wall of the expansion sleeve 1, the extrusion sleeve 4 is slidably arranged in the expansion sleeve 1, the bolt 2 is divided into a large column section 22 and a small column section 21, and the large column section 22 and the small column section 21 are respectively provided with threads, the threads of the large column section 22 are connected with the threads at the top of the inner side wall of the expansion sleeve 1, the extrusion sleeve 4 moves inward synchronously with the movement of the bolt 2 into the expansion sleeve 1, the outer side wall of the extrusion sleeve 4 abuts against the plurality of movable columns 3 and pushes the plurality of movable columns 3 to move outside the expansion sleeve 1, and the movable columns 3 are reset as the extrusion sleeve 4 is pulled out;

[0030] When the expansion sleeve 1 is made of a soft material such as plastic, it is difficult to use for a long time and is not suitable for high load conditions. When the expansion sleeve 1 is made of a hard material such as metal, after the metal expansion sleeve 1 is expanded by the enlarged head of the bolt 2 on one side of the mounting hole, if the expansion bolt 2 needs to be removed, the expansion sleeve 1 is difficult to remove due to the expansion and deformation, or the surrounding structure of the mounting hole is damaged after forcible removal, which brings inconvenience in use; on the other hand, the expansion sleeve 1 is also difficult to reuse after deformation; in order to make the installed expansion bolt 2 easy to remove and reuse, the expansion bolt 2 in the present invention only needs to be loosened by unscrewing the bolt 2 during the removal process, and the expansion sleeve 1 is not deformed, so it can be convenient for reuse next time.

[0031] Specifically, the extrusion sleeve 4 is slidably installed into the expansion sleeve 1, and then the thread on the large column section 22 of the bolt 2 is preliminarily connected with the thread on the inner wall of the expansion sleeve 1. It is only necessary to screw a few turns to connect the bolt 2 and the expansion sleeve 1 together, and then the entire expansion bolt 2 is placed in the installation hole of the wall or other required object, the installation hole is slightly larger than the outer wall diameter of the expansion sleeve 1, and then the bolt 2 is gradually tightened. At this time, a part of the small column section 21 of the bolt 2 is inserted into the extrusion sleeve 4, and the large column section 22 is threadedly connected with the expansion sleeve 1. When the bolt 2 is gradually screwed into the expansion sleeve 1, the small column section 21 will push the extrusion sleeve 4 to gradually extend into the part of the movable column 3 in the expansion sleeve 1. Since the diameter of the movable column 3 is greater than the wall thickness of the expansion sleeve 1, when the extrusion sleeve 4 is gradually squeezed toward the bottom of the expansion sleeve 1, the extrusion sleeve 4 will apply thrust to several movable columns 3, so that part of the side wall area of ​​the movable column 3 extends out of the expansion sleeve 1. As the extrusion sleeve 4 gradually moves toward the bottom, the thrust on the movable column 3 will also increase. Since the diameter of the mounting hole is only slightly larger than the diameter of the expansion sleeve 1, after a number of movable columns 3 are partially pushed out of the expansion sleeve 1, the overall diameter of the expansion sleeve 1 increases, forming an extrusion force on the mounting hole. By forming an extrusion force on the side wall of the mounting hole, the friction between the expansion bolt 2 and the mounting hole is increased, so that the expansion bolt 2 can be stably installed in the mounting hole.

[0032] In addition, since the bolt 2 part and the expansion sleeve 1 part of the general expansion bolt 2 need to be put into the installation hole at the same time, and then the bolt 2 part is rotated and pulled out, the expansion sleeve 1 is expanded during the process of the expansion head of the bolt 2 inside the installation hole being pulled out, so the bolt 2 needs to be partially pulled out of the installation hole, resulting in the expansion sleeve 1 inside the installation hole being hollow, and then the bearing capacity is reduced. When used for heavy loads, the expansion bolt 2 will form a lever inside and outside the installation hole, and a fulcrum will be formed at the bottom position of the installation hole outlet, which is easy to cause the expansion bolt 2 to be overstressed inside the installation hole.

[0033] In the expansion bolt 2 of this embodiment, since the expansion sleeve 1 is first installed in the installation hole and then the bolt 2 is gradually screwed in, the bolt 2 of the expansion bolt 2 of this embodiment is longer in length while the expansion bolt 2 is the same overall length. This can improve the bearing capacity of the expansion bolt 2 and prevent the bolt 2 from forming a large lever force with the external part of the bolt 2 due to insufficient depth in the installation hole. In addition, since the existing expansion bolt 2 needs to be pulled out partially during installation to expand the expansion sleeve 1, the installation hole needs to be drilled deeper during installation, which cannot be used when some floors or walls are thin, and may cause penetration after drilling.

[0034] When the expansion bolt 2 needs to be removed, it is only necessary to unscrew the bolt 2 from the expansion sleeve 1, and then take out the extrusion sleeve 4 to loosen several movable columns 3. The overall diameter of the expansion sleeve 1 is restored to be slightly smaller than the diameter of the installation hole, and it can be easily taken out without pulling out the entire expansion bolt 2 with force, which can prevent damage to the wall or floor where the installation hole is located, and the expansion bolt 2 after removal can also be reused.

[0035] Since in the above embodiment, after the extrusion sleeve 4 is pushed into the bottom of the expansion sleeve 1 by the bolt 2 and forms an extrusion thrust with the plurality of movable columns 3, when the expansion bolt 2 needs to be taken out again, the bolt 2 and the extrusion sleeve 4 need to be taken out to loosen the plurality of movable columns 3. However, in the above embodiment, when the extrusion sleeve 4 is removed, it is difficult to take it out because the extrusion sleeve 4 is subjected to the reverse extrusion force of the plurality of movable columns 3. In order to solve this problem, the extrusion sleeve 4 can be taken out when the bolt 2 is screwed out. Therefore, in one embodiment, the inner wall of the extrusion sleeve 4 is provided with a thread, and the inner wall of the extrusion sleeve 4 is threadedly connected with the small column section 21.

[0036] When installing the expansion bolt 2, first connect the thread on the small column section 21 of the bolt 2 with the thread on the inner wall of the extrusion sleeve 4, and only connect a small part, then install the extrusion sleeve 4 and the bolt 2 into the expansion sleeve 1 as a whole, and connect the thread on the large column section 22 of the bolt 2 with the thread on the inner wall of the expansion sleeve 1, and only connect a small part, then install the expansion bolt 2 into the installation hole, and then gradually tighten the bolt 2. As the bolt 2 is gradually tightened, the extrusion sleeve 4 also gradually forms an extrusion force on the several movable columns 3, and as the bolt 2 is tightened and the extrusion sleeve 4 gradually penetrates into the bottom of the expansion sleeve 1, the extrusion sleeve 4 and the movable column 3 interact with each other. The force is gradually increased, and the extrusion sleeve 4 can be prevented from rotating under the action of the extrusion force. The screwing in of the bolt 2 not only drives the bolt 2 to gradually extend into the expansion sleeve 1, but also the rotation of the bolt 2 connects the thread on the small column section 21 with the extrusion sleeve 4, and the extrusion sleeve 4 does not rotate due to the extrusion force, and the thread spacing between the large column section 22 and the expansion sleeve 1 is larger than the thread spacing between the small column section 21 and the extrusion sleeve 4. Therefore, the distance that the large column section 22 enters into the expansion sleeve 1 after one rotation is larger than the distance that the small column section 21 enters into the extrusion sleeve 4. Therefore, the rotation of the bolt 2 and the action of penetrating into the expansion sleeve 1 will also drive the extrusion sleeve 4 to gradually penetrate to the bottom of the expansion sleeve 1.

[0037] When the expansion bolt 2 needs to be removed, as the bolt 2 is screwed out, the extrusion sleeve 4 will not rotate under the reverse extrusion of the several movable columns 3. Therefore, when the bolt 2 is screwed out, the threads on the small column section 21 and the inner wall of the extrusion sleeve 4 will also rotate relatively, and the thread spacing between the large column section 22 and the expansion sleeve 1 is larger than the thread spacing between the small column section 21 and the extrusion sleeve 4. Therefore, the distance that the large column section 22 enters into the expansion sleeve 1 after one circle is larger than the distance that the small column section 21 enters into the extrusion sleeve 4. Therefore, as the bolt 2 is screwed out, the extrusion sleeve 4 will also be taken out, making the removal of the extrusion sleeve 4 more convenient.

[0038] In order to be able to push the several movable columns 3 through the extrusion sleeve 4 so that the several movable columns 3 are pushed out beyond the outside of the expansion sleeve 1 to form a pressurizing effect on the installation hole, when the outer wall of the extrusion sleeve 4 abuts against the movable column 3, it is necessary to make the diameter of the extrusion sleeve 4 plus the diameter of the two movable columns 3 larger than the diameter of the expansion sleeve 1. Therefore, when the extrusion sleeve 4 is reversely extruded toward the several movable columns 3 in the initial stage, the abutting end of the extrusion sleeve 4 is difficult to insert. In order to facilitate the installation of the extrusion sleeve 4 in the initial stage, in one embodiment, the diameter of the outer wall of the extrusion sleeve 4 gradually increases from the bottom to the top of the expansion sleeve 1, and the diameter of the several movable columns 3 gradually decreases from the bottom to the top of the expansion sleeve 1;

[0039] That is, the diameters of the ends where the extrusion sleeve 4 and the plurality of movable columns 3 are butted are relatively small, and the diameters of the ends that are gradually moving away are gradually increasing. Since the diameters of the butt ends of the two are relatively small, the butting end of the extrusion sleeve 4 can be easily inserted between the plurality of movable columns 3, and a preliminary butting force and friction force can be formed. When the extrusion sleeve 4 can be manually inserted into the deepest part of the movable column 3, the threads on the large column section 22 of the bolt 2 can also be connected with the threads on the inner wall of the expansion sleeve 1, so that the continued penetration of the extrusion sleeve 4 can be aided by the thrust of the bolt 2 being screwed in, making the installation of the extrusion sleeve 4 more convenient.

[0040] On the other hand, due to the inclination angles of the two, the squeezing force between the expansion bolt 2 and the mounting hole gradually increases during the tightening of the bolt 2. When it is tightened to a certain extent and cannot be tightened further, it means that it has been reinforced in place and no further tightening is required.

[0041] Since the installation holes of the general expansion bolts 2 include straight-through installation holes and bottom-expanded installation holes, the straight-through installation holes have the same diameter throughout the entire installation hole, while the bottom-expanded installation holes have the same diameter near the opening, and the bottom of the installation hole forms a conical expansion hole, the purpose of which is to enable the expanded head portion of the expansion bolt 2 to be in the expanded hole when the general expansion bolt 2 is used, to form a greater abutment force and friction force to prevent the expansion bolt 2 from being pulled out. In order to be applicable to these two types of installation holes, in one embodiment, the inclination angle of the outer wall of the extrusion sleeve 4 is one to two times the inclination angle of the plurality of movable columns 3, and the plurality of movable columns 3 are squeezed by the extrusion sleeve 4 to form an expanded head with two sides parallel or gradually increasing in inclination from the top to the bottom of the expansion sleeve 1 outside the expansion sleeve 1;

[0042] Since the extrusion sleeve 4 can be completely removed from the expansion sleeve 1, the extrusion sleeve 4 can be replaced as needed. When the mounting hole is a bottom expansion type mounting hole, an extrusion sleeve 4 with an inclination angle twice that of the movable column 3 is used, that is, the inclination angle of the extrusion sleeve 4 is the same as the inclination angle of the movable column 3. The inclination angle here refers to the inclination angle of the extrusion sleeve 4 and the movable column 3 from the large end to the small end compared to the general cylindrical shape. When the inclination angle of the extrusion sleeve 4 is the same as that of the movable column 3, since the movable column 3 is conical, the axial direction of the movable column 3 is parallel to the side wall of the mounting hole, and the side wall of the movable column 3 away from the extrusion sleeve 4 forms an inclination angle that gradually increases from the top to the bottom of the expansion sleeve 1, then the outside of the entire expansion sleeve 1 forms an enlarged head that gradually increases in inclination from the top to the bottom of the expansion sleeve 1, and the enlarged head is just in the enlarged hole;

[0043] When the mounting hole is a straight-through mounting hole, an extrusion sleeve 4 whose outer wall has an inclination angle twice that of the movable column 3 is used. The inclination angles on both sides of the movable column 3 are superimposed on each other to have the same size as the extrusion sleeve 4 whose single-side inclination angle is twice that of the movable column 3. When the outer side walls of the two are abutted, the side wall of the movable column 3 away from the extrusion sleeve 4 will form a parallel line with the side wall of the mounting hole, thereby providing the maximum friction force for the expansion bolt 2 through the maximum contact area.

[0044] In order to prevent the movable column 3 from falling off in the expansion sleeve 1 and making it difficult to install, in one embodiment, a plurality of movable cavities are arranged around the wall of the expansion sleeve 1, and each movable cavity corresponds to a movable column 3, and the plurality of movable cavities are used to limit the movable column 3 on the wall of the expansion sleeve 1; since the movable column 3 is an inclined cylindrical shape, the opening of the movable cavity needs to be slightly smaller than the diameter of the movable column 3, which can prevent the movable column 3 from falling off from the movable cavity on the one hand, and can also make the position of the movable column 3 smaller than the opening of the movable cavity protrude to the outside of the movable cavity on the other hand, so that the diameter of the expansion sleeve 1 increases after the movable column 3 protrudes from the opening position of the active cavity.

[0045] Since the extrusion sleeve 4 needs to exert a certain force when inserted between the several movable columns 3, and the diameter of the movable column 3 is slightly larger than the wall thickness of the expansion sleeve 1, the movable column 3 partially protrudes from the inner wall of the expansion sleeve 1, and its top is easy to form abutment with the extrusion sleeve 4 when it abuts against the extrusion sleeve 4, resulting in the extrusion sleeve 4 being unable to be inserted. Therefore, in one embodiment, the two end faces of the several movable columns 3 are hemispherical surfaces, and the abutment surfaces of the extrusion sleeve 4 and the several movable columns 3 are provided with rounded corners;

[0046] Both ends of the movable column 3 are hemispherical, while the ground interface of the extrusion sleeve 4 is rounded. When the two are in contact, a horizontal force can be formed on the movable columns 3 under the thrust of the extrusion sleeve 4, so that the movable columns 3 can be pushed around through the extrusion sleeve 4, and the top of the movable columns 3 will not collide with the bottom of the extrusion sleeve 4, so the extrusion sleeve 4 can be more convenient to install.

[0047] Since in the above embodiment, in order to gradually insert the extrusion sleeve 4 between the several movable columns 3 by screwing in the bolt 2, the extrusion sleeve 4 needs to be unable to rotate or the rotation amplitude cannot be too large during this process, so that the insertion of the extrusion sleeve 4 can be pushed by the rotation of the bolt 2, and the above embodiment can only prevent the rotation of the extrusion sleeve 4 by the friction and extrusion force between the extrusion sleeve 4 and the several movable columns 3. In order to further prevent the rotation of the extrusion sleeve 4, in one embodiment, the outer side wall of the extrusion sleeve 4 is provided with arc grooves corresponding to the number of the several movable columns 3, and the several arc grooves are arranged along the axial direction of the extrusion sleeve 4, and the inclination angle of the outer wall of the extrusion sleeve 4 is set in the arc groove, and the several arc grooves correspond to the several movable columns 3 in a one-to-one sliding abutment to prevent the rotation of the extrusion sleeve 4;

[0048] Since the number of the plurality of arc grooves is the same as the number of the plurality of movable columns 3, when installing the extrusion sleeve 4, it is first necessary to align one of the arc grooves of the extrusion sleeve 4 with one of the movable columns 3, and then preliminarily push the extrusion sleeve 4 in the direction of the movable column 3. After the extrusion sleeve 4 is manually pushed in until it cannot go any deeper and the thread of the large column section 22 is connected with the thread of the expansion sleeve 1, the bolt 2 is rotated so that the bolt 2 and the extrusion sleeve 4 are synchronously pushed into the expansion sleeve 1. When the extrusion sleeve 4 is gradually pushed in, the extrusion sleeve 4 is pushed in by The side wall of the extrusion sleeve 4 abuts against the side wall of the movable column 3, so the movable column 3 cannot be separated from the arc groove, which makes it difficult for the extrusion sleeve 4 to rotate. The extrusion sleeve 4 cannot rotate when the bolt 2 is screwed in, and the pitch of the large column section 22 of the bolt 2 is larger than the pitch of the small column section 21. Therefore, the distance that the large column section 22 inserts into the expansion sleeve 1 bolt after one rotation is larger than the distance that the small column section 21 inserts into the extrusion sleeve 4, so the rotation of the bolt 2 can push the extrusion sleeve 4 to be further inserted into the expansion sleeve 1. By setting the arc groove, and the inclination angle on the outer wall of the extrusion sleeve 4 in the above embodiment is within the arc groove, the arc groove can be used to limit the extrusion sleeve 4 on the one hand, and can push a number of movable columns 3 to form a horizontal or a certain inclination angle enlarged head on the other hand.

[0049] In order to facilitate the tightening of the bolt 2, in one embodiment, a rectangular section 23 is provided on the top of the bolt 2. The rectangular section 23 has four faces in the axial direction, and two faces are parallel to each other. The rectangular section 23 is used to tighten the bolt 2 with a tool. A wrench can act on the rectangular section 23. At the same time, the diagonal size of the rectangular section 23 cannot be larger than the diameter of the bolt 2 so that the nut can be installed on the bolt 2.

[0050] Since the expansion bolt 2 may be subjected to a force perpendicular to the direction of the mounting hole after installation, a shear force is formed on the bolt 2 under the force in the vertical direction. In the above embodiment, the bolt 2 is divided into a large column section 22 and a small column section 21, and a shoulder is formed between the large column section 22 and the small column section 21. The existence of the shoulder will cause stress concentration when this part is subjected to force, and it is easy to break after being subjected to force. In order to prevent this problem, in one embodiment, the shoulder between the large column section 22 and the small column section 21 is an inclined surface. Although the inclined surface of the shoulder will still make the shoulder a stress concentration point, the bearing capacity of this position can be increased as much as possible.

[0051] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. An expansion bolt, characterized in that: It includes a bolt, an expansion sleeve and an extrusion sleeve. A plurality of movable columns are arranged around the bottom of the side wall of the expansion sleeve and connect the inner and outer sides of the expansion sleeve. The diameters of the plurality of movable columns are larger than the thickness of the side wall of the expansion sleeve. The extrusion sleeve is slidably arranged in the expansion sleeve. The bolt is divided into a large column section and a small column section, and the large column section and the small column section are respectively provided with threads. The threads of the large column section are connected with the threads at the top of the inner wall of the expansion sleeve. The extrusion sleeve moves inward synchronously with the movement of the bolt into the expansion sleeve. The outer wall of the extrusion sleeve abuts against the plurality of movable columns and pushes the plurality of movable columns to move outside the expansion sleeve. The movable columns are reset when the extrusion sleeve is pulled out.

2. An expansion bolt according to claim 1, characterized in that: The inner wall of the extrusion sleeve is provided with threads, and the inner wall of the extrusion sleeve is threadedly connected with the small column section.

3. An expansion bolt according to claim 1, characterized in that: The diameter of the outer side wall of the extrusion sleeve gradually increases from the bottom to the top of the expansion sleeve.

4. An expansion bolt according to claim 3, characterized in that: The diameters of the plurality of movable columns gradually decrease from the bottom to the top of the expansion casing.

5. An expansion bolt according to claim 4, characterized in that: The inclination angle of the outer wall of the extrusion sleeve is one to two times the inclination angle of the plurality of movable columns. The plurality of movable columns are squeezed by the extrusion sleeve to form an enlarged head outside the expansion sleeve with two sides parallel or gradually increasing in inclination from the top to the bottom of the expansion sleeve.

6. An expansion bolt according to claim 1, characterized in that: A plurality of movable cavities are arranged around the wall of the expansion sleeve, each of the movable cavities corresponds to a movable column, and the plurality of movable cavities are used for correspondingly limiting the position of the movable column on the wall of the expansion sleeve.

7. An expansion bolt according to claim 1, characterized in that: Both end surfaces of the plurality of movable columns are hemispherical surfaces, and the contact surfaces between the extrusion sleeve and the plurality of movable columns are provided with rounded corners.

8. An expansion bolt according to claim 5, characterized in that: The outer wall of the extrusion sleeve is provided with arc grooves corresponding to the number of the movable columns, and the arc grooves are arranged along the axial direction of the extrusion sleeve. The inclination angle of the outer wall of the extrusion sleeve is set in the arc groove. The arc grooves correspond to the movable columns in a one-to-one sliding abutment to prevent the extrusion sleeve from rotating.

9. An expansion bolt according to claim 1, characterized in that: A rectangular section is provided on the top of the bolt. The rectangular section has four faces in the axial direction and two faces are parallel to each other. The rectangular section is used to tighten the bolt by using a tool.

10. An expansion bolt according to claim 1, characterized in that: The shoulder between the large column section and the small column section is an inclined surface.

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