A threaded nail for steel structures

Abstract

The present invention discloses a threaded nail for steel structures, belonging to the technical field of threaded nails. It includes a nail body, and the nail body includes a connecting section and an anchoring section connected to each other. A connecting thread is provided on the outer part of the connecting section; a through groove is opened at the end of the anchoring section, and the through groove extends from the end of the anchoring section far from the connecting section towards the end of the anchoring section close to the connecting section. This application has the effects of increasing the effective contact area and friction force between the nail head and the base body, improving the fusion welding effect, and increasing the pulling force.

Description

Technical Field

[0001] The present invention relates to the technical field of threaded nails, and in particular to a threaded nail for steel structures. Background Art

[0002] A nail is a kind of nail that is driven into a building body by using a blank cartridge, gas or an electric nail gun. With the development of industry, the demand for nails in steel structure buildings and steel structure equipment is also increasing. At present, the blunt-headed nails used for steel structures in the market are mainly cylindrical-headed threaded nails with a circular cross-sectional area, and in recent years, the market has higher and higher requirements for the pull-out force value of the nails.

[0003] In related technologies, when installing a blunt-headed nail with a circular cross-section, it is necessary to pre-drill a blind hole in the base body, and then use a nail gun to drive the nail into it. Through the rapid friction work between the nail and the base body to generate heat, the nail and the base body are welded together to ensure a certain pull-out force. By setting a sealing washer at the nail head of the nail, air and moisture can be prevented from entering the joint surface between the nail and the base body, so as to achieve the purpose of preventing oxidation and corrosion. And, in order to improve the pull-out force of the existing blunt-headed nails, mainly by changing the diameter of the cylindrical head to increase the effective contact surface area between the nail and the base body, so as to increase the pull-out force of the nail.

[0004] In view of the above related technologies, the applicant found that when the existing nail is driven into the pre-drilled blind hole, the front part of the end of the nail will squeeze or peel off the base body near the surface of the blind hole, which easily leads to insufficient extrusion force of the end of the nail driven into the base body and poor welding effect, resulting in an unsatisfactory pull-out force. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the present invention provides a threaded nail for steel structures, which can increase the effective contact area and friction force between the nail head and the base body, improve the welding effect, and thus increase the pull-out force.

[0006] The technical solution of the present invention to solve the above technical problems is as follows:

[0007] A threaded nail for steel structures, including a nail body, the nail body includes a connecting section and an anchoring section connected to each other, and a connecting thread is provided on the outer surface of the connecting section; a through groove is opened at the end of the anchoring section, and the through groove extends from the end of the anchoring section away from the connecting section to the end of the anchoring section close to the connecting section.

[0008] By adopting the above technical solution, during the installation of the nail body, since the diameter of the anchoring section at the head of the nail body is larger than the diameter of the blind hole in the base body, the part with a through groove opened at the end of the anchoring section is first squeezed. The reserved gap in the through groove makes the part with a through groove opened at the end of the anchoring section more easily squeezed and deformed. Then, the degree of extrusion damage to the outer end of the pre-drilled blind hole in the base body is smaller. Thus, the latter half of the anchoring section at the end of the nail body fully squeezes and rubs against the blind hole, forming a larger friction area and a larger extrusion force, thereby increasing the acting force between the nail and the surface of the pre-drilled blind hole in the base body, forming a good fusion welding effect, and further improving the pulling force of the nail.

[0009] Further, the depth direction of the through groove is arranged along the axial direction of the anchoring section, and the through groove can be in a shape of a straight line, a cross, or an X.

[0010] By adopting the above technical solution, when the through groove axially opened at the end of the anchoring section is in a shape of a straight line, a cross, or an X, during the installation of the nail body, the part with a through groove opened at the end of the anchoring section can be easily squeezed and deformed, so that the latter half of the anchoring section fully squeezes and rubs against the blind hole, increasing the effective contact surface area between the nail and the base body, and further improving the fusion welding effect and increasing the pulling force of the nail.

[0011] Further, the anchoring section can be any one of a cylindrical structure, a frustum of a cone structure, or an inverted frustum of a cone structure. When the anchoring section is a frustum of a cone structure, the end of the anchoring section close to the connecting section is the large head end, and the other end is the small head end; when the anchoring section is an inverted frustum of a cone structure, the end of the anchoring section close to the connecting section is the small head end, and the other end is the large head end.

[0012] By adopting the above technical solution, when the anchoring section is a cylindrical structure, a frustum of a cone structure, or an inverted frustum of a cone structure, after a through groove is opened at the end of the anchoring section, the part with a through groove opened at the end of the anchoring section can be easily squeezed and deformed, thereby increasing the effective contact area and friction force between the anchoring section and the base body, improving the fusion welding effect, and increasing the pulling force.

[0013] Further, the length of the anchoring section is set as H, and the groove depth of the through groove is set to be 1 / 6H to H.

[0014] By adopting the above technical solution, when the groove depth of the through groove ranges from 1 / 6 of the length of the anchoring section to the through groove completely penetrating the anchoring section, the pulling force value of the nail can be improved to a certain extent; and the appropriate groove depth can be determined through experiments according to different diameters of the anchoring section and the requirements of the pulling force to achieve the best pulling force.

[0015] Further, when the anchoring section is a cylindrical structure, the groove depth of the through groove is set to be 1 / 2H to 2 / 3H.

[0016] By adopting the above technical solution, when the anchoring section is a cylindrical structure and the groove depth of the through groove is 1 / 2 to 2 / 3 of the length of the anchoring section, the improvement effect of the nail pulling force value is better.

[0017] Further, the width of the through groove is 0.1 to 0.5 millimeters.

[0018] By adopting the above technical solution, when the groove width of the through groove is 0.1 to 0.5 millimeters, the nail pulling force value of the nail can be improved to a certain extent; and the appropriate groove width can be determined through experiments according to the anchoring section with different diameters and the requirements of the pulling force, so as to achieve the best pulling force.

[0019] Further, knurling is provided on the outside of the anchoring section.

[0020] By adopting the above technical solution, the knurling provided on the outside of the anchoring section can further increase the effective contact surface area between the nail and the base body, thereby further improving the fusion welding effect and increasing the pulling force of the nail.

[0021] Further, a chamfer is provided at one end of the anchoring section away from the connecting section.

[0022] By adopting the above technical solution, the chamfer at the end of the anchoring section makes it easier for the anchoring section at the end of the nail body to be inserted into the blind hole opened on the base body, and can greatly reduce the damage to the anchoring section at the end of the nail body, thereby greatly increasing the service life of the nail.

[0023] Further, a pressing ring is provided on the outside of the nail body, and the pressing ring is located at the connection position between the connecting section and the anchoring section.

[0024] By adopting the above technical solution, the pressing ring at the connection position between the connecting section and the anchoring section on the nail body can play a role in restricting and stopping the depth of the nail inserted into the blind hole on the base body, and finally achieve the effect of protecting the external connection thread of the connecting section and fixing the nail.

[0025] Further, the pressing ring has a horn-shaped structure, and the size of the connection end of the pressing ring with the nail body is smaller than the size of the connection end away from the nail body.

[0026] By adopting the above technical solution, the pressing ring has a horn-shaped structure, and a sealing washer can be provided on the side of the pressing ring facing the anchoring section. When the anchoring section is inserted into the blind hole on the base body, the sealing washer abuts against the surface of the base plate; through the mutual cooperation of the horn-shaped pressing ring and the sealing washer, the sealing washer can be tightly pressed against the base plate, thereby greatly improving the connection stability between the nail and the base plate.

[0027] In summary, compared with the prior art, the beneficial effects of the above technical solutions are:

[0028] (1) When the threaded nail is shot into the blind hole of the base at high speed, when the end of the anchoring section contacts the blind hole, there is an instantaneous maximum impact force. At this moment, the welding temperature has not been reached yet. Under the strong impact, the base material on the surface of the blind hole will be directly extruded and peeled off, which will reduce the welding surface on the inner wall of the blind hole. Moreover, due to the influence of the peeled material, the welding effect in the blind hole is affected. By providing a through groove at the end of the anchoring section, when the end of the anchoring section contacts the blind hole instantaneously, the end of the anchoring section will have a slight contraction, thus avoiding mechanical damage to the inner wall of the blind hole. During the process of shooting the threaded nail, better welding effect can be generated due to the gradual friction between the nail and the base, which can increase the acting force between the nail and the surface of the pre-drilled blind hole on the base, and thus improve the pulling force of the nail. In addition, when the nail is shot into the bottom of the blind hole, it will also rebound due to the restoring force of the through groove, and it does not affect the welding effect between the periphery of the through groove and the inner wall of the blind hole.

[0029] (2) When the anchoring section is in a cylindrical structure, a conical frustum structure or an inverted conical frustum structure, after providing a through groove in the shape of a straight line, a cross or an X at the end of the anchoring section, the part of the anchoring section with the through groove at the end is easily extruded and deformed, which can increase the effective contact area and friction force between the anchoring section and the base, improve the welding effect and increase the pulling force.

[0030] (3) When the groove depth of the through groove is from 1 / 6 of the length of the anchoring section to the through groove completely penetrating the anchoring section, the pulling force value of the nail can be improved to a certain extent. Description of the Drawings

[0031] Figure 1 It is a schematic diagram of the overall structure of the threaded nail in Embodiment 1 of the present application;

[0032] Figure 2 It is a schematic diagram of the overall structure of the threaded nail in Embodiment 2 of the present application;

[0033] Figure 3 It is a schematic diagram of the overall structure of the threaded nail in Embodiment 3 of the present application;

[0034] Figure 4 It is a schematic diagram of the overall structure of the threaded nail in Embodiment 4 of the present application;

[0035] Figure 5 It is a schematic diagram of the overall structure of the threaded nail in Embodiment 5 of the present application;

[0036] Figure 6 It is a schematic diagram of the overall structure of the threaded nail in Embodiment 6 of the present application;

[0037] Figure 7 It is a schematic diagram of the overall structure of the threaded nail in Embodiment 7 of the present application;

[0038] Figure 8This is a schematic diagram of the overall structure of the threaded nail in Embodiment 8 of the present application;

[0039] Figure 9 This is a schematic diagram of the overall structure of the threaded nail in Embodiment 9 of the present application.

[0040] Explanation of reference numerals: 1, nail body; 11, connecting section; 12, anchoring section; 2, connecting thread; 3, through groove; 4, knurling; 5, chamfer; 6, pressing ring. Detailed implementation manners

[0041] The following Figures 1-9 describes the principles and features of the present invention. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0042] Embodiment 1 of the present application discloses a threaded nail for steel structures.

[0043] Embodiment 1

[0044] Referring Figure 1 , the threaded nail includes a nail body 1, and the nail body 1 includes an integrally formed connecting section 11 and an anchoring section 12. The connecting section 11 has a cylindrical structure, and a connecting thread 2 is provided on the outer part of the connecting section 11 for connecting an external mounting member. During the installation of the nail, the anchoring section 12 on the nail body 1 is inserted into a blind hole pre-drilled in the base body.

[0045] An annular pressing ring 6 is integrally connected to the outer part of the nail body 1, and the pressing ring 6 is located at the connection position between the connecting section 11 and the anchoring section 12, so as to limit and stop the depth of insertion of the nail into the blind hole in the base body, thereby playing a role in protecting the connecting thread 2 on the outer part of the connecting section 11 and fixing the nail.

[0046] The pressing ring 6 has a flared structure, and the size of the connection end of the pressing ring 6 with the nail body 1 is smaller than the size of the end far from the connection end of the nail body 1. When a sealing washer is provided on the side of the pressing ring 6 facing the anchoring section 12, as the anchoring section 12 is inserted into the blind hole in the base body, the sealing washer can be made to abut against the surface of the base plate, and finally the sealing washer presses tightly against the base plate, thereby achieving the effect of improving the connection stability between the nail and the base plate.

[0047] A chamfer 5 is provided at one end of the anchoring section 12 far from the connecting section 11, which can make the anchoring section 12 at the end of the nail body 1 more easily inserted into the blind hole opened in the base body, so as to reduce the damage to the anchoring section 12 at the end of the nail body 1, thereby greatly improving the service life of the nail.

[0048] A through groove 3 is provided at the end of the anchoring section 12. The depth direction of the through groove 3 is arranged along the axial direction of the anchoring section 12, and the through groove 3 extends from the end of the anchoring section 12 away from the connecting section 11 towards the end of the anchoring section 12 close to the connecting section 11. During the process of inserting the anchoring section 12 at the end of the nail body 1 into the blind hole on the substrate, the part of the anchoring section 12 where the through groove 3 is provided at the end can be first squeezed, so that the part of the anchoring section 12 where the through groove 3 is provided at the end is deformed by extrusion, then the degree of extrusion damage to the blind hole on the substrate can be reduced, so that the part of the anchoring section 12 close to the connecting section 11 can fully squeeze and rub the blind hole, forming a larger friction area and a larger extrusion force, thereby increasing the acting force between the nail and the surface of the pre-drilled blind hole on the substrate, forming a good fusion welding effect and pulling force, and the increasing degree of the pulling force value can be obtained from the following experimental data.

[0049] Use a drill bit with a diameter φ of 4.7 mm to drill a blind hole with a depth of 6 mm on the Q345 steel plate.

[0050] Select five nail samples with the anchoring section 12 being a cylindrical structure, the diameter of the anchoring section 12 being 5.3 mm, and the length H of the anchoring section 12 being 6 mm. The pulling force values of the nail samples are shown in Table 1.

[0051] Select five nail samples with the anchoring section 12 being a cylindrical structure, the diameter of the anchoring section 12 being 5.3 mm, and the length H of the anchoring section 12 being 6 mm, and a through groove 3 with a linear structure is provided at the end of the anchoring section 12; the groove width of the through groove 3 is 0.2 mm, and the groove depth is 1 / 6H, that is, 1 mm. The pulling force values of the corresponding nail samples are shown in Table 1.

[0052] As can be seen from Table 1, after a through groove 3 with a linear structure with a groove width of 0.2 mm and a groove depth of 1 mm is provided at the end of the cylindrical anchoring section 12 with a diameter of 5.3 mm and a length of 6 mm, the average pulling force value increases by about 0.7 KN, about 5.3% increase, indicating that providing a through groove 3 at the end of the cylindrical anchoring section 12 can increase the pulling force value of the nail to a certain extent.

[0053] Table 1 Pulling force values of different cylindrical nail samples

[0054]

[0055]

[0056] Example 2

[0057] Refer to Figure 2 , the difference between this example and Example 1 is that the groove width of the through groove 3 is 0.2 mm, and the groove depth is 1 / 3H, that is, 2 mm. The pulling force values of the corresponding nail samples are shown in Table 1.

[0058] As can be seen from Table 1, after a through slot 3 with a width of 0.2 mm and a depth of 2 mm in a cross-shaped structure is opened at the end of the anchoring section 12 with a cylindrical structure having a diameter of 5.3 mm and a length of 6 mm, the average pulling force increases by approximately 2.9 KN, an increase of approximately 22%, further indicating that opening a through slot 3 at the end of the anchoring section 12 with a cylindrical structure can increase the pulling force value of the nail.

[0059] Example 3

[0060] Refer to Figure 3 , the difference between this example and Example 1 is that the width of the through slot 3 is 0.2 mm, and the depth is 1 / 2H, that is, 3 mm. The pulling force values of the corresponding nail samples are shown in Table 1.

[0061] As can be seen from Table 1, after a through slot 3 with a width of 0.2 mm and a depth of 3 mm in a cross-shaped structure is opened at the end of the anchoring section 12 with a cylindrical structure having a diameter of 5.3 mm and a length of 6 mm, the average pulling force increases by approximately 3.6 KN, an increase of approximately 27%, further indicating that opening a through slot 3 at the end of the anchoring section 12 with a cylindrical structure can increase the pulling force value of the nail.

[0062] Example 4

[0063] Refer to Figure 4 , the difference between this example and Example 1 is that the width of the through slot 3 is 0.2 mm, and the depth is 2 / 3H, that is, 4 mm. The pulling force values of the corresponding nail samples are shown in Table 1.

[0064] As can be seen from Table 1, after a through slot 3 with a width of 0.2 mm and a depth of 4 mm in a cross-shaped structure is opened at the end of the anchoring section 12 with a cylindrical structure having a diameter of 5.3 mm and a length of 6 mm, the average pulling force increases by approximately 4.9 KN, an increase of approximately 37%, further indicating that opening a through slot 3 at the end of the anchoring section 12 with a cylindrical structure can increase the pulling force value of the nail.

[0065] Example 5

[0066] Refer to Figure 5 , the difference between this example and Example 1 is that the width of the through slot 3 is 0.2 mm, and the depth is 5 / 6H, that is, 5 mm. The pulling force values of the corresponding nail samples are shown in Table 1.

[0067] As can be seen from Table 1, after a through groove 3 with a width of 0.2 mm and a depth of 5 mm in a straight-line structure is opened at the end of the anchoring section 12 with a cylindrical structure having a diameter of 5.3 mm and a length of 6 mm, the average value of the pulling force increases by about 2 kN, an increase of about 15%, further indicating that opening the through groove 3 at the end of the anchoring section 12 with a cylindrical structure can increase the pulling force value of the nail to a certain extent.

[0068] Example 6

[0069] Referring to Figure 6 , the difference between this example and Example 1 is that the width of the through groove 3 is 0.2 mm and the depth is H, which is 6 mm. The pulling force values of the corresponding nail samples are shown in Table 1.

[0070] As can be seen from Table 1, after a through groove 3 with a width of 0.2 mm and a depth of 6 mm in a straight-line structure is opened at the end of the anchoring section 12 with a cylindrical structure having a diameter of 5.3 mm and a length of 6 mm, the average value of the pulling force increases by about 0.5 kN, an increase of about 4%, further indicating that opening the through groove 3 at the end of the anchoring section 12 with a cylindrical structure can increase the pulling force value of the nail to a certain extent.

[0071] As can be seen from Examples 1-6, after a through groove 3 with a width of 0.2 mm in a straight-line structure is opened at the end of the anchoring section 12 with a cylindrical structure having a diameter of 5.3 mm and a length of 6 mm, the pulling force value first increases and then decreases as the depth of the through groove increases, indicating that the magnitude of the pulling force value is related to the grooving specifications of the through groove 3. And when the depth of the through groove 3 is 4 mm, the increase effect of the pulling force value is the best. And the maximum pulling force value can increase to 19.2 kN. Compared with the lowest pulling force value of 12.7 kN of the cylindrical nail, the pulling force value is increased by 51%. At this time, the increase degree of the pulling force value is the largest, greatly improving the performance of the nail.

[0072] From the above series of experimental results, it can be seen that it is better for the depth of the through groove on the cylindrical nail to reach two-thirds of the length of the anchoring section.

[0073] Example 7

[0074] Referring to Figure 7 , the difference between this example and Example 1 is that the anchoring section 12 is a frustum of a cone structure, and the end of the anchoring section 12 close to the connecting section 11 is the large end and the other end is the small end.

[0075] Three nail samples with the anchoring section 12 being a frustum of a cone structure, the large end diameter of the anchoring section 12 being 5.3 mm, the small end diameter being 5.25 mm, and the length H of the anchoring section 12 being 6 mm are selected. The pulling force values of the nail samples are shown in Table 2.

[0076] Select three nail samples with the anchoring section 12 being a frustum of a cone structure, the large-end diameter of the anchoring section 12 being 5.3 mm, the small-end diameter being 5.25 mm, and the length H of the anchoring section 12 being 6 mm, and a through groove 3 in the shape of a straight line is provided at the end of the anchoring section 12; the groove width of the through groove 3 is 0.2 mm, and the groove depth is 1 / 6H, that is, 1 mm. The pull-out force values of the corresponding nail samples are shown in Table 2.

[0077] As can be seen from Table 2, after a through groove 3 with a groove width of 0.2 mm and a groove depth of 1 mm in the shape of a straight line is provided at the end of the anchoring section 12 of the frustum of a cone structure with a large-end diameter of 5.3 mm and a small-end diameter of 5.25 mm, the average pull-out force increases by about 3.1 KN, about 21%, indicating that providing a through groove 3 at the end of the anchoring section 12 of the frustum of a cone structure can also increase the pull-out force value of the nail to a certain extent.

[0078] Table 2 Pull-out force values of different frustum of a cone-shaped nail samples

[0079]

[0080] Example 8

[0081] Refer to Figure 8 , the difference between this example and Example 3 is that the anchoring section 12 is an inverted frustum of a cone structure, and the end of the anchoring section 12 close to the connecting section 11 is the small end, and the other end is the large end.

[0082] Select three nail samples with the anchoring section 12 being an inverted frustum of a cone structure, the small-end diameter of the anchoring section 12 being 5.3 mm, the large-end diameter being 5.35 mm, and the length H of the anchoring section 12 being 6 mm. The pull-out force values of the nail samples are shown in Table 3.

[0083] Select three nail samples with the anchoring section 12 being an inverted frustum of a cone structure, the small-end diameter of the anchoring section 12 being 5.3 mm, the large-end diameter being 5.35 mm, and the length H of the anchoring section 12 being 6 mm, and a through groove 3 in the shape of a straight line is provided at the end of the anchoring section 12; the groove width of the through groove 3 is 0.2 mm, and the groove depth is 1 / 2H, that is, 3 mm. The pull-out force values of the corresponding nail samples are shown in Table 3.

[0084] As can be seen from Table 3, after a through groove 3 with a groove width of 0.2 mm and a groove depth of 3 mm in the shape of a straight line is provided at the end of the anchoring section 12 of the inverted frustum of a cone structure with a small-end diameter of 5.3 mm and a large-end diameter of 5.35 mm, the average pull-out force increases by about 4.8 KN, about 42%, indicating that providing a through groove 3 at the end of the anchoring section 12 of the inverted frustum of a cone structure can also increase the pull-out force value of the nail to a certain extent.

[0085] Table 3 Pull-out force values of different inverted frustum-shaped nail samples

[0086]

[0087] Example 9

[0088] Reference Figure 9 , the difference between this embodiment and Embodiment 3 is that a knurling 4 is provided on the outside of the anchoring section 12. The knurling 4 on the outside of the anchoring section 12 can further increase the effective contact surface area between the nail and the substrate, thereby further improving the fusion welding effect and increasing the pull-out force of the nail.

[0089] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A threaded nail for steel structures, comprising a nail body (1), characterized in that: The nail body (1) includes a connecting section (11) and an anchoring section (12) that are connected to each other. A connecting thread (2) is provided on the outer surface of the connecting section (11); a through groove (3) is formed at the end of the anchoring section (12), and the through groove (3) extends from the end of the anchoring section (12) far from the connecting section (11) towards the end of the anchoring section (12) close to the connecting section (11).

2. The threaded nail for steel structures according to claim 1, characterized in that: The depth direction of the through groove (3) is arranged along the axial direction of the anchoring section (12), and the through groove (3) is in a shape of a straight line, a cross or an X shape.

3. The threaded nail for steel structures according to claim 1 or 2, characterized in that: The anchoring section (12) is any one of a cylindrical structure, a frustum of a cone structure or an inverted frustum of a cone structure. When the anchoring section (12) is a frustum of a cone structure, the end of the anchoring section (12) close to the connecting section (11) is the large end, and the other end is the small end; when the anchoring section (12) is an inverted frustum of a cone structure, the end of the anchoring section (12) close to the connecting section (11) is the small end, and the other end is the large end.

4. The threaded nail for steel structures according to claim 1, characterized in that: The length of the anchoring section (12) is set as H, and the groove depth of the through groove (3) is set to be 1 / 6H to H.

5. The threaded nail for steel structures according to claim 4, characterized in that: When the anchoring section (12) is a cylindrical structure, the groove depth of the through groove (3) is set to be 1 / 2H to 2 / 3H.

6. The threaded nail for steel structures according to claim 1, characterized in that: The width of the through groove (3) is 0.1 to 0.5 millimeters.

7. The threaded nail for steel structures according to claim 1, characterized in that: Knurling (4) is provided on the outer surface of the anchoring section (12).

8. The threaded nail for steel structures according to claim 1, characterized in that: A chamfer (5) is provided at the end of the anchoring section (12) far from the connecting section (11).

9. The threaded nail for steel structures according to claim 1, characterized in that: A compression ring (6) is provided on the outer surface of the nail body (1), and the compression ring (6) is located at the connection position between the connecting section (11) and the anchoring section (12).

10. The threaded nail for steel structures according to claim 9, characterized in that: The compression ring (6) has a horn-shaped structure, and the size of the end of the compression ring (6) connected to the nail body (1) is smaller than the size of the end far from the connection with the nail body (1).

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