Double-taper screw expansion bolt

Abstract

The utility model discloses a double taper screw expansion bolt which comprises a screw, an expansion sleeve and a nut, the screw comprises a head part and a rod part, the head part is axially provided with a first taper layer, a buffer layer connected with the first taper layer and a second taper layer connected with the buffer layer, the conical surface angle of the second taper layer is greater than that of the first taper layer; the first taper layer and the second taper layer are axially arranged on the head portion of the screw rod of the expansion bolt, the first taper layer makes contact with the expansion sleeve when screwed, so that the expansion sleeve expands outwards, deforms and is self-locked and embedded into the base material to provide anchoring force, the expansion sleeve enters the second taper layer along with increase of screwing force, and therefore the anchoring effect is achieved. Due to the fact that the taper of the second taper layer is further expanded, the expansion sleeve is further expanded for self-locking, and the anchoring force is further expanded; along with the increase of the screwing force, the expansion sleeve reaches the tail end of the second taper layer, the maximum expansion effect is achieved at the moment, and the anchoring force reaches the maximum value.

Description

Technical Field

[0001] This utility model relates to the field of fasteners, and more specifically, to a double-tapered screw expansion bolt. Background Technology

[0002] An expansion bolt is a fastener that achieves high-strength anchoring through the principle of mechanical expansion. It typically consists of a bolt, an expansion sleeve, and a nut. During installation, tightening the nut causes the tapered head of the bolt to expand outwards from the sleeve, thus fixing it in the hole. As the tapered head moves, it compresses the expansion sleeve, causing it to expand. This generates friction, fixing it within the hole wall. Therefore, the magnitude of the fastening force is closely related to the bolt taper and the design of the expansion sleeve.

[0003] The existing expansion bolts have a single-tapered head design, with a taper design value typically between 8 and 15°. When the expansion sleeve is under force, it extends along the taper to form a tight engagement. When the bolt is screwed in too deeply, the taper head of the bolt will exceed the expansion section of the expansion sleeve, failing to trigger the radial expansion of the sleeve, resulting in a significant decrease in anchoring friction.

[0004] Utility model CN206257132U discloses an expansion bolt, including an expansion tube and a tapered fastening screw. The tapered fastening screw has an inner expansion ridge that mates with the rectangular groove of the expansion tube. The head of the tapered fastening screw is a single taper surface. During tightening, the expansion tube may extend beyond the head of the tapered fastening screw due to excessive screwing, resulting in a decrease in tightening force. At the same time, because the head of the tapered fastening screw is a single taper surface, when the nut is loosened, the limited friction of the single taper may result in an insecure wrapping, and the expansion tube may come out backward. Utility Model Content

[0005] This invention addresses the problem in existing expansion bolts where the single-tapered screw head extends beyond the expansion section of the expansion sleeve due to excessive screwing, thus preventing radial expansion of the expansion sleeve and resulting in decreased anchoring friction. It also solves the problem of existing expansion bolts becoming loose or the expansion sleeve slipping after the nut is loosened by providing a double-tapered screw expansion bolt.

[0006] The technical solution adopted in this utility model is:

[0007] A double-tapered screw expansion bolt includes a screw, an expansion sleeve sleeved on the screw, and a nut threadedly connected to the screw. The screw includes a head and a shank. The head is axially provided with a first tapered layer, a buffer layer connected to the first tapered layer, and a second tapered layer connected to the buffer layer. The first tapered layer is located at one end near the expansion sleeve, and the taper angle of the second tapered layer is greater than that of the first tapered layer.

[0008] Furthermore, the cone angle of the first tapered layer is 5 to 8°, the cone angle of the second tapered layer is 10 to 15°, and the angle of the buffer layer is smaller than the cone angle of the first tapered layer.

[0009] Furthermore, the outer surface of the head of the screw is provided with an axial groove.

[0010] Furthermore, the end of the screw head away from the expansion sleeve is chamfered.

[0011] Furthermore, the expansion sleeve has an expansion end one at one end near the screw head, and an expansion slit one is provided on the expansion end one.

[0012] Furthermore, the expansion end is also provided with a circular groove that connects to the expansion cut.

[0013] Furthermore, the expanded end is formed into a double-layer structure by bending inward.

[0014] Furthermore, the inner layer of the double-layer structure is provided with an inverted cone shape.

[0015] Furthermore, the side of the double-layer structure that contacts the screw is provided with a textured surface to increase resistance.

[0016] Furthermore, the diameter of the expansion bolt is 4–25 mm.

[0017] Compared with the prior art, the beneficial effects of this utility model are:

[0018] The expansion bolt of this invention has a first tapered layer and a second tapered layer connected to the first tapered layer axially arranged at the head of the bolt. When tightened, the first tapered layer contacts the expansion sleeve, causing the expansion sleeve to deform and embed into the substrate, providing anchoring force. As the tightening force increases, the expansion sleeve enters the second tapered layer. Due to the further expansion of the taper of the second tapered layer, the expansion sleeve further expands, thereby further increasing the anchoring force. As the tightening force increases, the expansion sleeve enters the end of the second tapered layer. At this time, the expansion sleeve reaches its maximum expansion effect, and the overall anchoring force of the expansion bolt also reaches its maximum value, which far exceeds that of conventional expansion bolts.

[0019] After the nut is tightened, the expansion sleeve of this invention will tightly wrap around the double-layer taper of the bolt head, forming a self-locking mechanism. Even if the nut is loosened, the bolt and expansion sleeve will not loosen or move back in the hole because the wrapping effect of the double-layer taper is much greater than that of conventional expansion bolts. Attached Figure Description

[0020] Figure 1 A schematic diagram of a double-tapered screw expansion bolt structure;

[0021] Figure 2This is a schematic diagram of the screw structure of a double-tapered screw expansion bolt;

[0022] Figure 3 A schematic diagram of an expansion sleeve structure for a double-tapered screw expansion bolt;

[0023] Figure 4 This is a schematic diagram of the expansion sleeve structure in Example 3;

[0024] Figure 5 This is a schematic diagram of the expansion sleeve double-layer structure in Example 3 after it is unfolded outwards and laid flat.

[0025] Among them: 1. Screw; 11. Second taper layer; 12. Buffer layer; 13. First taper layer; 14. Spiral groove; 2. Expansion sleeve; 21. Expansion end one; 22. Expansion notch one; 23. Circular groove; 24. Double-layer structure; 25. Inward fold; 3. Nut; 4. Washer. Detailed Implementation

[0026] To clearly illustrate the technical features of this solution, the present invention will be described in detail below through specific embodiments and in conjunction with the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application; however, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below. Furthermore, it should be understood in the description of this application that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" and "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified. In this application, unless otherwise explicitly specified and limited, the terms "installed," "connected," "linked," "fixed," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. In this application, unless otherwise explicitly specified and limited, "on" or "below" a second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that the specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples.

[0027] Example 1

[0028] Please see Figures 1 to 3This utility model provides an embodiment of a double-tapered screw expansion bolt, comprising a screw 1, an expansion sleeve 2 sleeved on the screw, and a nut 3 threadedly connected to the screw. The screw 1, expansion sleeve 2, and nut 3 are all made of steel. The screw 1 includes a head and a shank. The head is conical, and the lower end of the shank is provided with a spiral groove 14. The head is axially provided with a first tapered layer 13, a buffer layer 12 connected to the first tapered layer, and a second tapered layer 11 connected to the buffer layer. The taper angle of the second tapered layer 11 is greater than the taper angle of the first tapered layer 13. The taper angle is the angle formed by the axis of the cone containing the tapered layer and the generatrix.

[0029] Specifically, the first tapered layer 13 has a tapered angle of 5-8°, the second tapered layer 11 has a tapered angle of 10-15°, and the buffer layer 12 has a smaller angle than the first tapered layer 13. When tightening the expansion bolt, the expansion sleeve 2 first contacts the first tapered layer 13 and expands along the angle of the first tapered layer 13. As the expansion proceeds, the expansion sleeve 2 enters the buffer layer 12 with a slightly smaller angle, and finally contacts the second tapered layer 11. Since the angle of the second tapered layer 11 is greater than that of the first tapered layer 13, the expansion sleeve 2 expands further, thereby increasing the anchoring force. At the same time, the second tapered layer 11 increases the resistance to the expansion sleeve 2 continuing to deform and expand forward, preventing the end of the expansion sleeve 2 from pressing against the bottom of the substrate hole due to excessive tightening, which would damage the strength of the substrate. The outer surface of the head of the screw is provided with an axial groove to increase the static friction of the contact surface and prevent the expansion sleeve 2 from sliding on the screw 1.

[0030] The expansion sleeve 2 is provided with an expansion end 21, which contacts the head of the screw. The expansion end 21 is provided with an expansion notch 22, and the expansion end 21 is also provided with a circular groove 23 connected to the expansion notch 22. The expansion notch 22 expands under the tightening of the nut 3, and is inserted into the substrate to generate anchoring force. The circular groove 25 on the expansion notch can make the expansion end unfold at a larger angle, thereby increasing the gripping force of the expansion bolt at both ends.

[0031] During installation, first drill fixing holes in the wall according to the size of the expansion sleeve 2, then gently tap the expansion bolt into the fixing holes, and then tighten the nut 3. As the nut 3 is tightened, the first tapered layer 13 contacts the expansion sleeve 2, causing the expansion sleeve 2 to deform and embed into the substrate, providing anchoring force. As the tightening force increases, the expansion sleeve enters the second tapered layer 11. As the taper of the second tapered layer 11 further expands, the expansion sleeve 2 further expands, resulting in a further increase in anchoring force. As the tightening force increases, the expansion sleeve enters the end of the second tapered layer 11. At this time, the expansion sleeve 2 reaches its maximum expansion effect, and the overall anchoring force of the expansion bolt also reaches its maximum value, which is far greater than that of conventional expansion bolts. At the same time, the screw heads of the two stepped tapered layers are firmly wrapped with the expansion sleeve 2 to form a self-locking mechanism. Even if the nut 3 is loosened, the screw 1 and the expansion sleeve 2 will not loosen.

[0032] Example 2

[0033] Please see Figures 1 to 3 This utility model provides an embodiment of a double-tapered screw expansion bolt, comprising a screw 1, an expansion sleeve 2 sleeved on the screw, and a nut 3 threadedly connected to the screw. The screw 1, expansion sleeve 2, and nut 3 are all made of steel. The screw 1 includes a head and a shank. The head is conical, and the lower end of the shank is provided with a spiral groove 14. The head is axially provided with a first tapered layer 13, a buffer layer 12 connected to the first tapered layer, and a second tapered layer 11 connected to the buffer layer. The taper angle of the second tapered layer 11 is greater than the taper angle of the first tapered layer 13. The taper angle is the angle formed by the axis of the cone containing the tapered layer and the generatrix.

[0034] Specifically, the first tapered layer 13 has a tapered surface angle of 5–8°, the second tapered layer 11 has a tapered surface angle of 10–15°, and the buffer layer 12 has an angle smaller than that of the first tapered layer 13. When tightening the expansion bolt, the expansion sleeve 2 first contacts the first tapered layer 13 and expands along the angle of the first tapered layer 13. As the expansion proceeds, the expansion sleeve 2 enters the buffer layer 12 with a slightly smaller angle, and finally contacts the second tapered layer 11. Since the angle of the second tapered layer 11 is greater than that of the first tapered layer 13, the expansion sleeve 2 expands further, thereby increasing the anchoring force. At the same time, the second tapered layer 11 increases the resistance to the expansion sleeve 2 continuing to deform and expand forward, preventing the end of the expansion sleeve 2 from pressing against the bottom of the substrate hole due to excessive tightening, which would damage the strength of the substrate. The outer surface of the head of the screw is provided with an axial groove to increase the static friction of the contact surface and prevent the expansion sleeve 2 from sliding on the screw 1.

[0035] The expansion sleeve 2 is provided with an expansion end 21, which contacts the head of the screw. The expansion end 21 is provided with an expansion notch 22, and the expansion end 21 is also provided with a circular groove 23 connected to the expansion notch 22. The expansion notch 22 expands under the tightening of the nut 3, and is inserted into the substrate to generate anchoring force. The circular groove 25 on the expansion notch can make the expansion end unfold at a larger angle, thereby increasing the gripping force of the expansion bolt at both ends.

[0036] Furthermore, the double-tapered screw expansion bolt also includes a washer 4 sleeved on the screw 1 and in contact with the nut 3. The washer 4 is a flat washer or a spring washer. The washer 4 can effectively reduce the vibration of the expansion bolt and prevent it from loosening during long-term use.

[0037] During installation, first drill fixing holes in the wall according to the size of the expansion sleeve 2, then gently tap the expansion bolt into the fixing holes, and then tighten the nut 3. As the nut 3 is tightened, the first tapered layer 13 contacts the expansion sleeve 2, causing the expansion sleeve 2 to deform and embed into the substrate, providing anchoring force. As the tightening force increases, the expansion sleeve enters the second tapered layer 11. As the taper of the second tapered layer 11 further expands, the expansion sleeve 2 further expands, resulting in a further increase in anchoring force. As the tightening force increases, the expansion sleeve enters the end of the second tapered layer 11. At this time, the expansion sleeve 2 reaches its maximum expansion effect, and the overall anchoring force of the expansion bolt also reaches its maximum value, which is far greater than that of conventional expansion bolts. At the same time, the screw heads of the two stepped tapered layers are firmly wrapped with the expansion sleeve 2 to form a self-locking mechanism. Even if the nut 3 is loosened, the screw 1 and the expansion sleeve 2 will not loosen.

[0038] Example 3

[0039] Please see Figures 1 to 3 This utility model provides an embodiment of a double-tapered screw expansion bolt, comprising a screw 1, an expansion sleeve 2 sleeved on the screw, and a nut 3 threadedly connected to the screw. The screw 1, expansion sleeve 2, and nut 3 are all made of steel. The screw 1 includes a head and a shank. The head is conical, and the lower end of the shank is provided with a spiral groove 14. The head is axially provided with a first tapered layer 13, a buffer layer 12 connected to the first tapered layer, and a second tapered layer 11 connected to the buffer layer. The taper angle of the second tapered layer 11 is greater than the taper angle of the first tapered layer 13. The taper angle is the angle formed by the axis of the cone containing the tapered layer and the generatrix.

[0040] Specifically, the first tapered layer 13 has a tapered surface angle of 5–8°, the second tapered layer 11 has a tapered surface angle of 10–15°, and the buffer layer 12 has an angle smaller than that of the first tapered layer 13. When tightening the expansion bolt, the expansion sleeve 2 first contacts the first tapered layer 13 and expands along the angle of the first tapered layer 13. As the expansion proceeds, the expansion sleeve 2 enters the buffer layer 12 with a slightly smaller angle, and finally contacts the second tapered layer 11. Since the angle of the second tapered layer 11 is greater than that of the first tapered layer 13, the expansion sleeve 2 expands further, thereby increasing the anchoring force. At the same time, the second tapered layer 11 increases the resistance to the expansion sleeve 2 continuing to deform and expand forward, preventing the end of the expansion sleeve 2 from pressing against the bottom of the substrate hole due to excessive tightening, which would damage the strength of the substrate. The outer surface of the head of the screw is provided with an axial groove to increase the static friction of the contact surface and prevent the expansion sleeve 2 from sliding on the screw 1.

[0041] The expansion sleeve 2 is provided with an expansion end 21, which contacts the head of the screw. The expansion end 21 is provided with an expansion notch 22, and the expansion end 21 is also provided with a circular groove 23 connected to the expansion notch 22. The expansion notch 22 expands under the tightening of the nut 3, and is inserted into the substrate to generate anchoring force. The circular groove 25 on the expansion notch can make the expansion end unfold at a larger angle, thereby increasing the gripping force of the expansion bolt at both ends.

[0042] Furthermore, such as Figure 5 The fully unfolded diagram of the expansion sleeve shows that, after unfolding, an inward fold 25 is provided in the middle of the expansion cut 22. The expansion end 21 is formed into a double-layer structure 24 by downward inward folding. The inner layer forms an inverted cone structure. When the nut 4 is tightened, this structure will be pulled tighter and tighter, thereby increasing the anchoring force of the expansion bolt. At the same time, the side of the double-layer structure that contacts the screw is provided with a mesh pattern to increase resistance and prevent the expansion sleeve from sliding with the screw.

[0043] During installation, first drill fixing holes in the wall according to the size of the expansion sleeve, then gently tap the expansion bolt into the fixing holes, and then tighten the nut 3. As the nut 3 is tightened, the expansion end 1 expands and gets stuck into the wall substrate to form an anchoring force. At the same time, the inner inverted cone structure of the expansion end 21 will be pulled tighter and tighter when tightening, thereby improving the anchoring force of the expansion bolt.

[0044] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A dual taper screw expansion bolt comprising a screw, an expansion sleeve fitted over the screw, a nut threadably connected to the screw, characterised in that, The screw includes a head and a rod. The head is axially provided with a first tapered layer, a buffer layer connected to the first tapered layer, and a second tapered layer connected to the buffer layer. The first tapered layer is located at one end near the expansion sleeve, and the taper angle of the second tapered layer is greater than that of the first tapered layer.

2. A dual-tapered screw expansion bolt according to claim 1, wherein, The cone angle of the first tapered layer is 5 to 8°, the cone angle of the second tapered layer is 10 to 15°, and the angle of the buffer layer is smaller than the cone angle of the first tapered layer.

3. The double-tapered screw expansion bolt according to claim 1, characterized in that, The outer surface of the head of the screw is provided with an axial groove.

4. The double-tapered screw expansion bolt according to claim 1, characterized in that, The end of the screw head away from the expansion sleeve is chamfered.

5. The double-tapered screw expansion bolt according to claim 1, characterized in that, The expansion sleeve has an expansion end one at one end near the head of the screw, and an expansion slit one is provided on the expansion end one.

6. The double-tapered screw expansion bolt according to claim 5, characterized in that, The expansion end is also provided with a circular groove that connects to the expansion cut.

7. The double-tapered screw expansion bolt according to claim 5, characterized in that, The expanded end is formed into a double-layer structure by bending inward.

8. The double-tapered screw expansion bolt according to claim 7, characterized in that, The inner layer of the double-layer structure is provided with an inverted cone shape.

9. A double-tapered screw expansion bolt according to claim 7, characterized in that, The side of the double-layer structure that contacts the screw has a textured surface to increase resistance.

10. A double-tapered screw expansion bolt according to claim 1, characterized in that, The diameter of the expansion bolt is 4-25mm.

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