Interference thread pulling nail

Abstract

The utility model discloses an interference thread pulling nail which comprises a core rod, a nail body, a nail sleeve and a driving nut, a head boss is arranged at the first end of the core rod, the nail sleeve, the nail body and the driving nut are sequentially arranged on the core rod in a sleeved mode from the second end of the core rod, and a limiting boss of the nail body is provided with an outer end plane connected with the driving nut in an abutting mode. Wherein the interference thread pulling nail can be inserted into a mounting hole of a mounting surface, the limiting boss abuts against the mounting surface in an attached mode, and the outer diameter of the nail body is set according to the inner diameter of the mounting hole so that the nail body can be in interference fit with the mounting hole. According to the utility model, a gap between the nail body and the mounting hole is eliminated on the basis of the super-flat thread pulling nail, the mounting tightness and the bearing capacity are improved, a mounting interlayer and the interference thread pulling nail can generate certain compressive deformation and local residual compressive stress, the fatigue and other mechanical properties of the whole structure are facilitated, and the service life of the whole structure is prolonged. The risk that the structure is oxidized and corroded due to residual gas in the gap is avoided, and potential safety hazards caused by internal and external pressure difference are also avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of riveting structures, in particular to an interference thread pull-out nail. Background Art

[0002] With the improvement of aircraft sophistication, the control of aircraft weight is becoming increasingly strict. In order to reduce weight, composite materials are widely used in aircraft fuselage and wing skin. At the same time, these parts are generally compact and closed. Ordinary bolts, nuts, and rivets cannot meet the installation requirements of these occasions due to the need for double-sided installation. In this case, single-sided installation fasteners are generally selected, such as threaded pull-out nails, which mainly include a nail body, a core rod, a nail sleeve and a driving thread. When in use, first insert the assembled threaded pull-out nail into the preset installation hole, and then pull the core rod outward through the driving nut to deform the nail sleeve and form a large base, thereby locking it, and the core rod breaks from the breaking neck groove.

[0003] However, the outer end surface of the nail body of the existing threaded pull-out nail is provided with a groove that cooperates with the protrusion provided on the drive nut, so that the drive nut can be locked with the nail body. However, this will cause a large distance between the fracture surface of the core rod after fracture and the outer end surface of the nail body, with a maximum of 0.76 mm, resulting in a depression in the installation position of the threaded pull-out nail after installation, affecting the overall surface flatness and aerodynamic performance of the fuselage.

[0004] In order to improve this problem, the existing technology proposes an ultra-flat threaded puller nail, in which the groove set on the outer end face of the nail body is eliminated to make the outer end face of the nail body a plane, and the convex part of the driving nut is also eliminated accordingly, so that the distance between the fracture surface of the core rod after fracture and the outer end face of the nail body is controlled within 0.3mm, thereby improving the flatness of the installation position of the threaded puller nail after installation, and at the same time, the tensile and fatigue properties of the threaded puller nail itself are also improved. Utility Model Content

[0005] The inventors of the present utility model discovered that the existing ultra-flat threaded puller nails cannot use the convex part of the driving nut to squeeze and expand the nail body because the groove of the nail body and the convex part of the driving nut are eliminated, resulting in a loose fit between the nail body and the mounting hole and a gap. On the one hand, this reduces the tightness and load-bearing capacity of the threaded puller nail installation, which is not conducive to the fatigue and other mechanical properties of the overall structure of the threaded puller nail. On the other hand, gas is easily retained in the gap, which increases the risk of oxidation and corrosion of the threaded puller nail. At the same time, the internal and external pressure difference will also become a safety hazard of the aircraft structure.

[0006] The utility model aims to provide an interference thread pull-out nail, so as to solve the technical problem that the nail body of the current super-flat thread pull-out nail and the mounting hole are not tightly matched and there is a gap.

[0007] The above-mentioned purpose of the present invention can be achieved by adopting the following technical solutions:

[0008] The utility model provides an interference thread pull-out nail, comprising a core rod, a nail body, a nail sleeve and a drive nut, wherein the first end of the core rod is provided with a head boss, the nail sleeve, the nail body and the drive nut are sequentially sleeved on the core rod from the second end of the core rod, the first end of the nail sleeve abuts against the head boss, the second end of the nail sleeve is sleeved on the first end of the nail body, the second end of the nail body is provided with a limiting boss, the limiting boss has an outer end plane abutting against the drive nut; wherein, the interference thread pull-out nail can be inserted into the mounting hole of the mounting surface, the limiting boss abuts against the mounting surface, and the outer diameter of the nail body is set according to the inner diameter of the mounting hole so that the nail body can have an interference fit with the mounting hole.

[0009] In an embodiment of the present invention, the outer diameter of the nail body is D, and the inner diameter of the mounting hole is d, which has the relationship: 0.05mm≤(Dd)≤0.15mm.

[0010] In an embodiment of the present invention, the outer diameter D of the nail body and the inner diameter d of the mounting hole have a relationship of: Dd=0.10 mm.

[0011] In an embodiment of the present utility model, a guide cone is provided at the first end of the nail body, and the guide cone is gradually tapered toward the direction of the nail sleeve to guide the second end of the nail sleeve to be sleeved on the first end of the nail body. The guide cone is connected to one end of the main body of the nail body through a circular arc transition portion, and the other end of the main body of the nail body is connected to the limiting boss.

[0012] In an embodiment of the present invention, the arc radius of the arc transition portion is R, and has a range of: 1.0mm≤R≤2.0mm.

[0013] In an embodiment of the present invention, the main body of the nail body, the arc transition portion and the outer wall surface of the guide cone portion are all coated with lubricating material to form a surface lubricating layer.

[0014] In an embodiment of the present invention, the lubricating material is aviation aluminum coating or molybdenum disulfide-based lubricant.

[0015] In an embodiment of the present utility model, the nail body is provided with a threaded hole, the core rod is provided with an external threaded surface threadedly connected to the threaded hole, and a gap is provided between the external threaded surface and the threaded hole.

[0016] In an embodiment of the present invention, the median diameter of the threaded hole is D0, and the median diameter of the external threaded surface is d0, which have the relationship of 0.15 mm ≤ (D0-d0) ≤ 0.25 mm.

[0017] In an embodiment of the present invention, the median diameter D0 of the threaded hole and the median diameter d0 of the external threaded surface have a relationship of 0.21 mm ≤ (D0 - d0) ≤ 0.23 mm.

[0018] The features and advantages of this utility model are:

[0019] The interference thread pull-out nail of the utility model is based on the super-flat thread pull-out nail. By setting the outer diameter of the nail body according to the inner diameter of the mounting hole, after the interference thread pull-out nail is installed, the nail body can be interference-fitted with the mounting hole, thereby eliminating the gap between the nail body and the mounting hole. On the one hand, it improves the tightness and load-bearing capacity of the interference thread pull-out nail installation. On the other hand, it enables the installation interlayer and the interference thread pull-out nail to produce a certain compression deformation and local residual compressive stress, which is beneficial to the fatigue and other mechanical properties of the overall structure. On the other hand, it avoids the risk of oxidation corrosion of the structure due to residual gas in the gap, and also avoids the safety hazards caused by the internal and external pressure differences. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 It is a structural schematic diagram of the interference thread pulling nail in the utility model.

[0022] Figure 2 It is a structural schematic diagram of the nail body in the utility model.

[0023] Figure 3 It is a structural schematic diagram of the mounting hole in the utility model.

[0024] Figure 4 It is a schematic diagram of the structure of the interference thread pull-out nail after installation in the utility model.

[0025] Figure 5 It is a partial schematic diagram of the threaded connection between the nail body and the core rod in the utility model.

[0026] In the picture:

[0027] 1. Core rod; 11. Head boss; 12. External thread surface; 13. Neck breaking groove; 14. Fracture surface; 2. Nail body; 21. Limiting boss; 211. Outer end plane; 22. Main body; 23. Guide cone; 24. Arc transition part; 25. Threaded hole; 3. Nail sleeve; 4. Drive nut; 5. Mounting interlayer; 51. Mounting surface; 52. Mounting hole; 53. Inner surface. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] Combine Figures 1 to 4 As shown, the utility model provides an interference thread pull-out nail, comprising a core rod 1, a nail body 2, a nail sleeve 3 and a drive nut 4. The first end of the core rod 1 is provided with a head boss 11, the nail sleeve 3, the nail body 2 and the drive nut 4 are sequentially sleeved on the core rod 1 from the second end of the core rod 1, the first end of the nail sleeve 3 is abutted against the head boss 11, the second end of the nail sleeve 3 is sleeved on the first end of the nail body 2, and the second end of the nail body 2 is provided with a limiting boss 21, the limiting boss 21 has an outer end plane 211 abutting against the drive nut 4; wherein, the interference thread pull-out nail can be inserted into the mounting hole 52 of the mounting surface 51, the limiting boss 21 is abutted against the mounting surface 51, and the outer diameter D of the nail body 2 is set according to the inner diameter d of the mounting hole 52 so that the nail body 2 can be interference fit with the mounting hole 52.

[0030] Specifically, a broken neck groove 13 is also provided on the core rod 1. The mounting surface 51 is the outer side surface of the mounting interlayer 5, and the mounting hole 52 is a through hole that penetrates along the thickness direction of the mounting interlayer 5. The installation process of the interference thread pull-out nail is as follows: insert the assembled interference thread pull-out nail into the mounting hole 52 from one side of the mounting surface 51 until the limiting boss 21 of the nail body 2 is in contact with the mounting surface 51, so that the nail sleeve 3 and the head boss 11 of the core rod 1 pass through the mounting hole 52 and extend to the inner side of the mounting interlayer 5, and then rotate the drive nut 4 to pull the core rod 1 outward, and the core rod 1 drives the nail sleeve 3 to move outward (that is, move toward the side close to the mounting interlayer 5), so that the nail sleeve 3 gradually expands, and the sleeve length on the nail body 2 also increases. Gradually increase, and then continue to pull the core rod 1 outward, so that the nail sleeve 3 abuts against the inner side surface 53 of the installation interlayer 5, and then the nail sleeve 3 is deformed under the extrusion of the inner side surface 53 of the installation interlayer 5 and the head boss 11 of the core rod 1 to form a large bottom foot, so that the installation interlayer 5 is locked by utilizing the large bottom angle formed by the limiting boss 21 of the nail body 2 and the nail sleeve 3, and then the core rod 1 is broken from the breaking neck groove 13. The distance between the fracture surface 14 of the core rod 1 after breaking and the outer end plane 211 of the nail body 2 can be controlled within 0.3mm.

[0031] The interference thread pull-out nail of the present invention, based on the super-flat thread pull-out nail, sets the outer diameter D of the nail body 2 according to the inner diameter d of the mounting hole 52, so that after the interference thread pull-out nail is installed, the nail body 2 can be interference-fitted with the mounting hole 52, thereby eliminating the gap between the nail body 2 and the mounting hole 52. On the one hand, it improves the tightness and load-bearing capacity of the interference thread pull-out nail installation, and on the other hand, it enables the installation interlayer 5 and the interference thread pull-out nail to produce a certain compression deformation and local residual compressive stress, which is beneficial to the fatigue and other mechanical properties of the overall structure. On the other hand, it avoids the risk of oxidation corrosion of the structure due to residual gas in the gap, and also avoids the safety hazards caused by the internal and external pressure differences.

[0032] In order to eliminate the gap while more reasonably controlling the compressive deformation and local residual compressive stress generated by installing the interlayer 5 and the interference thread pull-out nail, and also facilitating the installation of the interference thread pull-out nail, preferably, 0.05mm≤(Dd)≤0.15mm. More preferably, Dd=0.10mm.

[0033] Combine Figures 1 to 4 As shown, the first end of the nail body 2 is provided with a guide cone 23, which is gradually tapered in the direction of the nail sleeve 3 (i.e., the insertion direction Z of the interference thread nail) so that the second end of the guide nail sleeve 3 can be sleeved on the first end of the nail body 2. However, during installation, the guide cone 23 of the nail body 2 needs to pass through the mounting hole 52 and extend to the inner side of the mounting interlayer 5. In the embodiment of the present invention, the guide cone 23 is connected to one end of the main body 22 of the nail body 2 via a circular arc transition portion 24, and the other end of the main body 22 of the nail body 2 is connected to the limiting boss 21. By providing the circular arc transition portion 24, the resistance between the nail body 2 and the hole wall of the mounting hole 52 is reduced, so that the guide cone 23 of the nail body 2 can pass through the mounting hole 52 more smoothly and extend to the inner layer of the mounting interlayer 5. In addition, compared with the cone angle formed by the direct connection between the guide cone 23 and the main body 22, the circular arc transition portion 24 in the present invention can avoid scratching the hole wall of the mounting hole 52. In order to more reasonably control the resistance between the arc transition portion 24 and the hole wall of the mounting hole 52 , preferably, the arc radius of the arc transition portion 24 is R, which has a range of 1.0 mm ≤ R ≤ 2.0 mm.

[0034] Combine Figure 2 and Figure 4 As shown, in order to further reduce the resistance between the nail body 2 and the wall of the mounting hole 52, in the embodiment of the present invention, the outer wall surfaces of the main body 22, the arc transition portion 24, and the guide cone 23 of the nail body 2 are all coated with a lubricating material to form a surface lubricating layer. The lubricating material can be an aviation aluminum paint or a molybdenum disulfide-based lubricant.

[0035] like Figure 1As shown, the nail body 2 is provided with a threaded hole 25, and the core rod 1 is provided with an external threaded surface 12 threadedly connected to the threaded hole 25. In order to avoid the nail body 2 being squeezed by the mounting hole 52 during installation and causing the nail body 2 and the core rod 1 to be stuck, making it difficult to pull the core rod 1 outward, as shown in FIG. Figure 5 As shown, in an embodiment of the present invention, a clearance exists between the external threaded surface 12 and the threaded hole 25. Preferably, the clearance between the external threaded surface 12 and the threaded hole 25 is controlled by controlling the difference in their pitch diameters. The pitch diameter of the threaded hole 25 is D0, and the pitch diameter of the external threaded surface 12 is d0, with the relationship: 0.15mm≤(D0-d0)≤0.25mm. More preferably, the pitch diameter D0 of the threaded hole 25 and the pitch diameter d0 of the external threaded surface 12 are in the relationship: 0.21mm≤(D0-d0)≤0.23mm.

[0036] Combine Figures 1 to 5 In order to better understand the technical solution of the present invention, two specific embodiments are provided below:

[0037] In a specific embodiment, the inner diameter d of the mounting hole 52 is 5.13 mm, and the outer diameter D of the nail body 2 is 5.21 mm. After the interference thread nail is installed, the nail body 2 and the mounting hole 52 have an interference fit; the arc radius R of the arc transition portion 24 between the main body 22 of the nail body 2 and the guide cone 23 is 1.0 mm; the surface of the main body 22 of the nail body 2 is coated with aviation aluminum paint for surface lubrication; the major diameter D1 of the external thread surface 12 of the nail body 2 is 3.61 mm, the middle diameter D0 is 3.22 mm, and the minor diameter D2 is 3.02 mm; the major diameter d1 of the threaded hole 25 of the core rod 1 is 3.37 mm, the middle diameter d0 is 3.01 mm, and the minor diameter d2 is 2.67 mm, respectively.

[0038] In another specific embodiment, the inner diameter d of the mounting hole 52 is 6.60 mm, and the outer diameter D of the nail body 2 is 6.71 mm. After the interference thread nail is installed, the nail body 2 and the mounting hole 52 are interference fit; the arc radius R of the arc transition portion 24 between the main body 22 of the nail body 2 and the guide cone 23 is 2.0 mm; the surface of the main body 22 of the nail body 2 is coated with a molybdenum disulfide-based lubricant for surface lubrication treatment; the major diameter D1 of the external thread surface 12 of the nail body 2 is 4.94 mm, the middle diameter D0 is 4.45 mm, and the minor diameter D2 is 4.16 mm; the major diameter d1 of the threaded hole 25 of the core rod 1 is 4.65 mm, the middle diameter d0 is 4.22 mm, and the minor diameter d2 is 3.76 mm, respectively.

[0039] The above are only several embodiments of the present invention. Those skilled in the art may make various changes or modifications to the embodiments of the present invention based on the contents disclosed in the application documents without departing from the spirit and scope of the present invention.

Claims

1. An interference thread puller, characterized in that: The nail body comprises a core rod, a nail body, a nail sleeve and a drive nut, wherein the first end of the core rod is provided with a head boss, the nail sleeve, the nail body and the drive nut are sequentially sleeved on the core rod from the second end of the core rod, the first end of the nail sleeve abuts against the head boss, the second end of the nail sleeve is sleeved on the first end of the nail body, the second end of the nail body is provided with a limiting boss, and the limiting boss has an outer end plane abutting against the drive nut; The interference threaded nail can be inserted into the mounting hole of the mounting surface, the limiting boss is pressed against the mounting surface, and the outer diameter of the nail body is set according to the inner diameter of the mounting hole so that the nail body can be interference fit with the mounting hole.

2. The interference thread pull-out nail according to claim 1, characterized in that: The outer diameter of the nail body is D, and the inner diameter of the mounting hole is d, which has the relationship: 0.05mm≤(Dd)≤0.15mm.

3. The interference thread puller according to claim 2, characterized in that: The outer diameter D of the nail body and the inner diameter d of the mounting hole have a relationship of Dd=0.10 mm.

4. The interference thread puller according to claim 1, characterized in that: The first end of the nail body is provided with a guide cone, which is gradually tapered toward the direction of the nail sleeve to guide the second end of the nail sleeve to be sleeved on the first end of the nail body. The guide cone is connected to one end of the main body of the nail body through an arc transition portion, and the other end of the main body of the nail body is connected to the limiting boss.

5. The interference thread pull-out nail according to claim 4, characterized in that: The arc radius of the arc transition portion is R, and has a range of: 1.0mm≤R≤2.0mm.

6. The interference thread pull-out nail according to claim 4, characterized in that: The main body of the nail body, the arc transition portion and the outer wall surfaces of the guide cone portion are all coated with lubricating material to form a surface lubricating layer.

7. The interference thread pull-out nail according to claim 6, characterized in that: The lubricating material is aluminum coating for aviation or molybdenum disulfide-based lubricant.

8. The interference thread pull-out nail according to claim 1, characterized in that: The nail body is provided with a threaded hole, and the core rod is provided with an external threaded surface threadedly connected to the threaded hole, with a gap between the external threaded surface and the threaded hole.

9. The interference thread pull-out nail according to claim 8, characterized in that: The median diameter of the threaded hole is D0, and the median diameter of the external threaded surface is d0, which have the relationship of 0.15 mm ≤ (D0-d0) ≤ 0.25 mm.

10. The interference thread puller nail according to claim 9, characterized in that: The median diameter D0 of the threaded hole and the median diameter d0 of the external threaded surface have the relationship: 0.21 mm ≤ (D0 - d0) ≤ 0.23 mm.

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