An expansion bolt

Abstract

The present invention belongs to the technical field of expansion bolts, and particularly relates to an expansion bolt; it includes a bolt, an expansion sleeve and an extrusion sleeve. A plurality of movable columns are circumferentially arranged at the bottom of the side wall of the expansion sleeve and communicate with both the inside and outside of the expansion sleeve. The diameters of the plurality of movable columns are larger than the wall thickness of the side wall of the expansion sleeve. The extrusion sleeve is slidably arranged inside the expansion sleeve. The bolt is divided into a large column section and a small column section, and threads are respectively arranged on the large column section and the small column section. The thread of the large column section is connected to the thread at the top of the inner side wall of the expansion sleeve. The extrusion sleeve moves inward synchronously with the movement of the bolt into the expansion sleeve. The outer side wall of the extrusion sleeve abuts against the plurality of movable columns and pushes the plurality of movable columns to move outward of the expansion sleeve. The movable columns reset as the extrusion sleeve is pulled out. Threads are arranged on the inner wall of the extrusion sleeve, and the inner wall of the extrusion sleeve is threadedly connected to the small column section; it can facilitate disassembly and reuse.

Description

Technical Field

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

[0002] An expansion bolt is a fastener used to fix pipeline supports / hangers / brackets or equipment on walls, floors, or columns. An expansion bolt usually consists of the following parts: a countersunk head bolt: mainly for connection and fixation, with a specific thread and taper design; an expansion sleeve: cooperating with the bolt, when the bolt is tightened, the expansion sleeve will expand outward and form a tight contact with the fixed body; flat washers and spring washers: used to increase the stability of the connection part and prevent loosening; a hexagonal nut: used to tighten the bolt, so that the expansion sleeve expands and is fixed on the fixed body. These components work together to achieve the fastening and fixing functions through a specific mechanism. The working principle of the expansion bolt is mainly based on the frictional grip force. When the bolt is screwed into a pre-drilled hole, the tapered part of the bolt will force the expansion sleeve to expand outward and form a tight contact with the hole wall. As the nut is further tightened, the bolt continues to stretch outward, and the expansion sleeve fits more tightly against the hole wall, thus generating a strong frictional grip force to firmly connect the bolt and the fixture together.

[0003] When the expansion sleeve 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 situations. When the expansion sleeve is made of a hard material such as metal, after the expansion sleeve of metal is expanded by the enlarged head on one side of the bolt in the installation hole, if it is necessary to remove the expansion bolt, the expansion sleeve is difficult to remove due to expansion deformation, or the surrounding structure of the installation hole is damaged after forced extraction, bringing inconvenience in use; at the same time, it is also difficult to reuse the expansion sleeve after deformation. Moreover, for a general expansion bolt, the bolt part and the expansion sleeve part need to be synchronously placed into the installation hole, and then the bolt part is rotated and pulled out. During the process of pulling out the enlarged head of the bolt inside the installation hole, the expansion sleeve is expanded. Therefore, the bolt needs to be pulled out a part from the installation hole, resulting in a hollow part of the expansion sleeve inside the installation hole, and thus the bearing capacity decreases. When used in heavy-duty situations, a lever will be formed inside and outside the installation hole of the expansion bolt, and a fulcrum will be formed at the bottom position of the outlet of the installation hole, easily causing excessive force on the inner part of the installation hole of the expansion bolt.

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

[0006] The object of the present invention can be achieved by the following technical solutions:

[0007] An expansion bolt of the present invention includes a bolt, an expansion sleeve, and an extrusion sleeve. A number of movable columns are arranged around the bottom of the side wall of the expansion sleeve and communicate with both the inside and outside of the expansion sleeve. The diameter of a number of the movable columns is larger than the wall thickness of the side wall of the expansion sleeve. The extrusion sleeve is slidably arranged inside the expansion sleeve. The bolt is divided into a large column section and a small column section, and threads are respectively arranged on both the large column section and the small column section. The thread of the large column section is connected to the thread at the top of the inner side wall of the expansion sleeve. The extrusion sleeve moves inward synchronously with the movement of the bolt into the expansion sleeve. The outer side wall of the extrusion sleeve abuts against a number of the movable columns and pushes a number of the movable columns to move outward of the expansion sleeve. The movable columns are reset as the extrusion sleeve is pulled out.

[0008] Further, threads are arranged on the inner wall of the extrusion sleeve, and the inner wall of the extrusion sleeve is threadedly connected to the small column section.

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

[0010] Further, the diameter of a number of the movable columns gradually decreases from the bottom to the top of the expansion sleeve.

[0011] Further, the inclination angle of the outer wall of the extrusion sleeve is one to two times the inclination angle of a number of the movable columns. A number of the movable columns form an enlarged head with parallel sides on both sides or an enlarged head with an inclination gradually increasing from the top to the bottom of the expansion sleeve outside the expansion sleeve as the extrusion sleeve is squeezed.

[0012] Further, a number of movable cavities are arranged around the wall of the expansion sleeve. Each of the movable cavities corresponds to one movable column, and a number of the movable cavities are used for limiting the position of the corresponding movable column on the wall of the expansion sleeve.

[0013] Further, both end faces of a number of the movable columns are hemispherical surfaces, and rounded corners are provided on the abutting surfaces of the extrusion sleeve and a number of the movable columns.

[0014] Further, arc-shaped grooves corresponding to the number of a number of the movable columns are arranged on the outer side wall of the extrusion sleeve, and a number of the arc-shaped grooves are arranged along the axial direction of the extrusion sleeve. The inclination angle of the outer wall of the extrusion sleeve is arranged in the arc-shaped grooves, and a number of the arc-shaped grooves are slidably abutted against a number of the movable columns one by one to prevent the extrusion sleeve from rotating.

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

[0016] Further, 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 as follows:

[0018] (1) By sliding the extrusion sleeve into the expansion sleeve, 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 placing the entire expansion bolt into the installation hole in the wall or other objects to be installed, and then gradually tightening the bolt. When the bolt is gradually screwed into the expansion sleeve, the extrusion sleeve will exert a thrust on several movable columns, causing a partial area of the side wall of the movable column to protrude outside the expansion sleeve, increasing the overall diameter of the expansion sleeve, forming a squeezing force on the installation hole and completing the installation. When it is necessary to remove the expansion bolt, just unscrew the bolt from the expansion sleeve, and then take out the extrusion sleeve. After the several movable columns are loosened, it can be easily taken out, and the removed expansion bolt can also be reused;

[0019] (2) By first installing the expansion sleeve in the installation hole and then gradually screwing the bolt in, on the basis of the same overall length of the expansion bolt, the effective insertion length of the bolt part of the expansion bolt in the present invention into the installation hole and the expansion sleeve is longer, which can improve the bearing capacity of the expansion bolt while preventing the bolt from forming a large lever force with the external part of the bolt due to insufficient depth in the installation hole;

[0020] (3) When installing the expansion bolt, the bolt is respectively connected to the threads on the inner walls of the extrusion sleeve and the expansion sleeve, 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 of the bolt not only drives the bolt to gradually extend into the expansion sleeve. Since the thread pitch between the large column section and the expansion sleeve is larger than the thread pitch between the small column section and the extrusion sleeve, the distance that the large column section enters the expansion sleeve in one turn is larger than the distance that the small column section enters the extrusion sleeve. Therefore, the rotation and the action of the bolt extending into the expansion sleeve will also drive the extrusion sleeve to gradually penetrate deeper into the bottom of the expansion sleeve; and when it is necessary to remove the expansion bolt, the extrusion sleeve will be taken out as the bolt is unscrewed. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] For the convenience of those skilled in the art to understand, the present invention will be further described below with reference to the accompanying drawings.

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

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

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

[0025] Figure 4Schematic diagram of the external structure of the expansion bolt of the present invention;

[0026] Figure 5 Schematic diagram of the structure of the expansion bolt of the present invention installed in the installation hole.

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

[0028] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following will, in conjunction with the accompanying drawings and preferred embodiments, describe in detail the specific embodiments, structures, features and their effects according to the present invention.

[0029] As Figures 1-5 shown, an expansion bolt of the present invention includes 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 communicate with the inside and outside of the expansion sleeve 1. The diameters of the plurality of movable columns 3 are larger than the wall 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 threads are respectively arranged on the large column section 22 and the small column section 21. The thread of the large column section 22 is connected to the thread on 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 towards the outside of the expansion sleeve 1. The movable columns 3 reset as the extrusion sleeve 4 is pulled out;

[0030] Since it is difficult to use the expansion sleeve 1 for a long time when it is made of a soft material such as plastic and it is not suitable for high-load situations, and when the expansion sleeve 1 is made of a hard material such as metal, after the expansion sleeve 1 made of metal is expanded by the enlarged head on one side of the bolt 2 in the installation hole, if it is necessary to remove the expansion bolt 2, the expansion sleeve 1 is difficult to remove due to expansion deformation, or the structure around the installation hole is damaged after being forcibly pulled out, bringing inconvenience in use; on the other hand, it is also difficult to reuse the expansion sleeve 1 after deformation; in order to make the installed expansion bolt 2 easy to remove and reusable, in the expansion bolt 2 of the present invention, only the bolt 2 needs to be screwed out during the removal process to achieve loosening, and the expansion sleeve 1 is not deformed and can be easily used next time.

[0031] Specifically, slide the extrusion sleeve 4 into the expansion sleeve 1, and then preliminarily 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. Only need to screw a few turns to connect the bolt 2 with the expansion sleeve 1. Then, place the entire expansion bolt 2 into the installation hole in the wall or other objects. The installation hole is slightly larger than the outer diameter of the expansion sleeve 1, and then gradually tighten the bolt 2. At this time, a part of the small column section 21 of the bolt 2 is inserted into the extrusion sleeve 4, while 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 a partial position of the movable column 3 inside the expansion sleeve 1. Since the diameter of the movable column 3 is larger than the wall thickness of the expansion sleeve 1, when the extrusion sleeve 4 gradually squeezes towards the bottom of the expansion sleeve 1, the extrusion sleeve 4 will apply a thrust to several movable columns 3, causing the side wall of the movable column 3 to protrude outside the expansion sleeve 1 in some areas. As the extrusion sleeve 4 gradually moves towards the bottom, the thrust on the movable column 3 will also be greater. Since the diameter of the installation hole is only slightly larger than the diameter of the expansion sleeve 1, after several movable columns 3 are partially pushed out of the expansion sleeve 1, the overall diameter of the expansion sleeve 1 increases, forming a squeezing force on the installation hole. By forming a squeezing force on the side wall of the installation hole, the friction between the expansion bolt 2 and the installation hole is increased, enabling the expansion bolt 2 to be stably installed in the installation hole.

[0032] In addition, since the bolt 2 part and the expansion sleeve 1 part of a general expansion bolt 2 need to be synchronously placed into the installation hole, and then the bolt 2 part is rotated and pulled out. During the process of pulling out the enlarged head of the bolt 2 inside the installation hole to expand the expansion sleeve 1, the bolt 2 needs to be pulled out a part from the installation hole, resulting in a hollow part of the expansion sleeve 1 inside the installation hole, and thus the bearing capacity decreases. When used in heavy-duty situations, a lever will be formed between the expansion bolt 2 inside and outside the installation hole, with the bottom position of the outlet of the installation hole as the fulcrum, which easily causes excessive force on the part of the expansion bolt 2 inside the installation hole.

[0033] For the expansion bolt 2 in this embodiment, since the expansion sleeve 1 is first installed in the installation hole and then the bolt 2 is gradually screwed in, on the basis of the same overall length of the expansion bolt 2, the effective insertion length of the bolt 2 part of the expansion bolt 2 in this embodiment into the installation hole and the expansion sleeve 1 is longer. It can improve the bearing capacity of the expansion bolt 2 while preventing a large lever force from being formed between the bolt 2 and the external part of the bolt 2 due to insufficient depth of the bolt 2 in the installation hole. And because the existing expansion bolt 2 needs to be pulled out a part during installation for the enlarged head to expand the expansion sleeve 1, the installation hole needs to be drilled deeper during installation. In the state where some floors or walls are relatively thin, it cannot be used, which may cause penetration after drilling.

[0034] When the expansion bolt 2 needs to be removed, simply unscrew the bolt 2 from the expansion sleeve 1, and then take out the extrusion sleeve 4. After the several movable columns 3 are loosened, the overall diameter of the expansion sleeve 1 returns to slightly smaller than the diameter of the installation hole, and it can be easily taken out without forcefully pulling out the entire expansion bolt 2, which can prevent damage to the wall or floor where the installation hole is located. The removed expansion bolt 2 can also be reused.

[0035] In the above embodiment, after the extrusion sleeve 4 is pushed by the bolt 2 to the bottom of the expansion sleeve 1 and forms an extrusion thrust with several movable columns 3, when the expansion bolt 2 needs to be removed again, the bolt 2 and the extrusion sleeve 4 need to be taken out to loosen the several movable columns 3. However, in the above embodiment, when removing the extrusion sleeve 4, since the extrusion sleeve 4 is subjected to the reverse extrusion force of several movable columns 3, it is relatively difficult to take out. To solve this problem and enable the extrusion sleeve 4 to be taken out along with the bolt 2 when the bolt 2 is unscrewed, in one embodiment, the inner wall of the extrusion sleeve 4 is provided with threads, and the inner wall of the extrusion sleeve 4 is threadedly connected to the small column section 21.

[0036] When installing the expansion bolt 2, first connect the threads on the small column section 21 of the bolt 2 to the threads on the inner wall of the extrusion sleeve 4, and only connect a small part. Then, the extrusion sleeve 4 and the bolt 2 are integrally inserted into the expansion sleeve 1, and the threads on the large column section 22 of the bolt 2 are connected to the threads on the inner wall of the expansion sleeve 1, also only connecting a small part. Then, the expansion bolt 2 is inserted into the installation hole, and the bolt 2 is gradually tightened. Since during the process of gradually tightening the bolt 2, the extrusion sleeve 4 also gradually forms an extrusion force on several movable columns 3, and as the bolt 2 is tightened and the extrusion sleeve 4 gradually penetrates to the bottom of the expansion sleeve 1, the extrusion interaction force between the extrusion sleeve 4 and the movable columns 3 gradually increases. Under the action of the extrusion force, the rotation of the extrusion sleeve 4 can be prevented. The screwing of the bolt 2 not only drives the bolt 2 to gradually extend into the expansion sleeve 1, but also because the rotation of the bolt 2 causes the threads on the small column section 21 to be connected to the extrusion sleeve 4, and since the extrusion sleeve 4 is subjected to the extrusion force and does not rotate, and the thread pitch between the large column section 22 and the expansion sleeve 1 is larger than the thread pitch between the small column section 21 and the extrusion sleeve 4, the distance that the large column section 22 enters the expansion sleeve 1 in one turn is larger than the distance that the small column section 21 enters the extrusion sleeve 4. Therefore, the rotation and the action of the bolt 2 extending 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 it is necessary to remove the expansion bolt 2, as the bolt 2 is unscrewed, since the extrusion sleeve 4 will not rotate under the reverse extrusion of several movable columns 3, when the bolt 2 is unscrewed, the small column section 21 and the threads on the inner wall of the extrusion sleeve 4 will rotate relative to each other. And the thread pitch between the large column section 22 and the expansion sleeve 1 is larger than the thread pitch between the small column section 21 and the extrusion sleeve 4. Therefore, the distance that the large column section 22 enters the expansion sleeve 1 in one turn is larger than the distance that the small column section 21 enters the extrusion sleeve 4. Therefore, as the bolt 2 is unscrewed, the extrusion sleeve 4 will also be taken out accordingly, making it more convenient to take out the extrusion sleeve 4.

[0038] In order to be able to push several movable columns 3 through the extrusion sleeve 4, so that several movable columns 3 are pushed out beyond the expansion sleeve 1 to form a pressurizing effect on the installation hole. Therefore, 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 two movable columns 3 larger than the diameter of the expansion sleeve 1. Therefore, when the extrusion sleeve 4 is squeezed in the reverse direction of several movable columns 3 at the initial stage, the abutting end of the extrusion sleeve 4 is difficult to insert. In order to make the extrusion sleeve 4 easy to install at 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 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 several movable columns 3 are butted are both small, and the diameters of the ends that are gradually far away gradually increase. Since the diameters of their butting ends are both small, the abutting end of the extrusion sleeve 4 can be easily inserted between several movable columns 3, and preliminary abutting force and frictional force can be formed. And when the extrusion sleeve 4 can be manually inserted to the deepest part of the movable column 3, the threads on the large column section 22 of the bolt 2 can also be connected to the threads on the inner wall of the expansion sleeve 1, making it more convenient to continue to insert the extrusion sleeve 4 with the thrust of screwing in the bolt 2.

[0040] On the other hand, due to their inclination angles, during the tightening process of the bolt 2, the extrusion force between the expansion bolt 2 and the installation hole gradually increases. When it cannot be tightened any further after being tightened to a certain extent, it means that the reinforcement is in place and there is no need to continue tightening.

[0041] Since the mounting holes of the general expansion bolt 2 include straight-through mounting holes and bottom-expanded mounting holes, the straight-through mounting hole has the same diameter throughout the mounting hole, while the bottom-expanded mounting hole has the same diameter near the opening, and a conical expansion is formed at the bottom of the mounting hole. The purpose is to enable the enlarged head portion of the expansion bolt 2 to be located within the expanded hole when using the general expansion bolt 2, forming a greater abutting force and frictional force to prevent the expansion bolt 2 from being pulled out. In order to be applicable to these two types of mounting 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. The plurality of movable columns 3 form an enlarged head with parallel sides or an inclination gradually increasing from the top to the bottom of the expansion sleeve 1 outside the expansion sleeve 1 as the extrusion sleeve 4 is extruded.

[0042] Since the extrusion sleeve 4 can be completely removed from outside the expansion sleeve 1, the extrusion sleeve 4 can be replaced as needed. When the mounting hole is a bottom-expanded mounting hole, an extrusion sleeve 4 with an inclination angle equal to that of the movable column 3 is used, that is, the inclination angle of the extrusion sleeve 4 is the same as that of the movable column 3. Here, the inclination angle refers to the angle of inclination of the large end to the small end of the extrusion sleeve 4 and the movable column 3 compared to a general cylindrical shape. When the inclination angles of the extrusion sleeve 4 and the movable column 3 are the same, 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 gradually increasing from the top to the bottom of the expansion sleeve 1. Then, an enlarged head with an inclination gradually increasing from the top to the bottom of the expansion sleeve 1 is formed outside the entire expansion sleeve 1, and the enlarged head is just located within the enlarged hole.

[0043] When the mounting hole is a straight-through mounting hole, an extrusion sleeve 4 with an inclination angle of the outer wall twice that of the movable column 3 is used. The sum of the inclination angles on both sides of the movable column 3 is the same as the angle of the extrusion sleeve 4 with twice the single-sided inclination angle of the movable column 3. After 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, providing the maximum frictional force for the expansion bolt 2 through the largest contact area.

[0044] In order to prevent the movable column 3 from falling within the expansion sleeve 1, making it difficult to install, in one embodiment, a plurality of movable cavities are provided around the wall of the expansion sleeve 1. Each movable cavity corresponds to a movable column 3, and the plurality of movable cavities are used to limit the position of the movable column 3 on the wall of the expansion sleeve 1. Since the movable column 3 is an inclined cylinder, the opening of the movable cavity needs to be slightly smaller than the diameter of the movable column 3. On the one hand, it prevents the movable column 3 from falling out of the movable cavity, and on the other hand, it also enables the position of the movable column 3 smaller than the opening of the movable cavity to protrude outside the movable cavity, increasing the diameter of the expansion sleeve 1 after the movable column 3 protrudes from the opening position of the movable cavity.

[0045] Since a certain force needs to be applied when the extrusion sleeve 4 is inserted between several movable columns 3, and the diameter of the movable column 3 is slightly larger than the wall thickness of the expansion sleeve 1, a part of the movable column 3 protrudes inside the inner side wall of the expansion sleeve 1, and its top is likely to abut against the extrusion sleeve 4 when contacting it, resulting in the inability to insert the extrusion sleeve 4. Therefore, in one embodiment, both end faces of several movable columns 3 are hemispherical, and the contact surface between the extrusion sleeve 4 and several movable columns 3 is provided with rounded corners;

[0046] Both ends of the movable column 3 are hemispherical, while the contact surface of the extrusion sleeve 4 is rounded. When they contact each other, a horizontal force on several movable columns 3 can be formed under the thrust of the extrusion sleeve 4, facilitating the pushing of several movable columns 3 to the surroundings by the extrusion sleeve 4, and its top will not abut against the bottom of the extrusion sleeve 4, so that the installation of the extrusion sleeve 4 can be more convenient.

[0047] Since in the above embodiment, in order to gradually insert the extrusion sleeve 4 between several movable columns 3 by screwing in the bolt 2, and in this process, the extrusion sleeve 4 cannot rotate or the rotation amplitude cannot be too large to push the insertion of the extrusion sleeve 4 through the rotation of the bolt 2. In the above embodiment, only the friction and extrusion force between the extrusion sleeve 4 and several movable columns 3 can prevent the rotation of the extrusion sleeve 4. 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-shaped grooves corresponding to the number of several movable columns 3, and several arc-shaped grooves are arranged along the axial direction of the extrusion sleeve 4. The inclination angle of the outer wall of the extrusion sleeve 4 is arranged in the arc-shaped grooves, and several arc-shaped grooves are slidably contacted with several movable columns 3 one by one 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 are only the preferred embodiments of the present invention and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above in the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments of equivalent changes within the scope of the technical solution of the present invention by using the technical content disclosed above. However, as long as it does not depart from the content of the technical solution of the present invention, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. An expansion bolt, characterized in that: It 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 are connected to the inner and outer sides of the expansion sleeve, the diameter of the plurality of movable columns is greater than the wall 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 side wall of the expansion sleeve, the extrusion sleeve moves inward synchronously with the movement of the bolt into the expansion sleeve, the outer side 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; 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; The diameter of the outer wall of the extrusion sleeve gradually increases from the bottom to the top of the expansion sleeve; The diameters of the movable columns gradually decrease from the bottom to the top of the expansion casing; 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.

2. 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.

3. 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.

4. An expansion bolt according to claim 1, 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.

5. 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 a tool.

6. 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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