Self-tapping fastener

Abstract

The present document relates to a novel thread profile geometry of a self-tapping fastener, wherein the fastener (1) comprises a head (2), a circular shank (3) provided with a main thread (30), and a secondary thread (31) arranged at an opposite end (32) to the head (2). The fastener (1) further comprises a thread start taper (α) on the outer diameter of each ridge (34) until the outer diameter of the ridges (34) of the main threads (30) is reached, and the ridges (34) of the secondary threads (31) are interrupted by at least one relief (4) positioned on the radial perimeter of the fastener (1), ensuring that during application, the fasteners (1) permanently deform the substrate in which they are installed, creating the female thread, in which the fastener engagement area is generated.

Description

[0001] Self-tapping fastener

[0002] FIELD OF APPLICATION

[0003]

[0001] This document refers to a new thread profile geometry for a self-tapping fastener, in which, during its application, the fasteners permanently deform the substrate where they are installed, creating the female thread, where the fastener engagement area is generated. Advantageously, the tip and thread fillet of these new fasteners reduce friction with the substrate, which consequently reduces the insertion torque, increases the maximum joint torque and increases the generated bonding force.

[0004] STATE OF THE ART

[0005]

[0002] Fasteners, such as screws, are widely used in various industrial and domestic applications. Therefore, fasteners are of great importance in our daily lives, more specifically in the industrial sector, which constantly seeks new technologies to improve performance, reduce costs, and increase competitiveness in different segments. However, many conventional fasteners have limitations in terms of torque, strength, and ease of installation.

[0006]

[0003] Among the fastener options available on the market are self-tapping screws, which are designed to automatically fasten to a substrate as they are applied. Furthermore, self-tapping screws offer advantages compared to standard joint fasteners (screw + nut), including: reduced cost, as they eliminate the nut; faster fastening, since they don't require adjustments and tightening of nuts; and reduced production processes.

[0007]

[0004] A peculiar characteristic of self-tapping fasteners is the thread geometry, which has a specific profile that, when inserted, facilitates penetration into the material, minimizing effort during installation or even eliminating the need for pre-drilling depending on the substrate material. The use of these geometries helps the industry reach new levels in assembly, as it promotes greater reliability in bolted joints, increased structural safety, since the screw generates better fixation in the substrate, minimizing the risk of loosening.

[0008]

[0005] The state of the art is constantly improving the geometries related to self-tapping fasteners, in order to improve the assembly parameters. The importance of the geometries used in a fastener is highlighted, since an optimized lamination of the substrate generates a thread with greater load-bearing capacity and, therefore, the fastener geometry plays a fundamental role in creating the application torque windows, so that the lower the installation torque and the higher the maximum torque required for shearing the rolled thread, the better the result of the bonding force generated for a fastener in a self-tapping application.

[0009]

[0006] One of the most widely used thread geometries in the self-tapping fastener segment is the trilobular, which consists of a fastener with a substantially triangular cross-section and rounded edges. Due to the reduction in its cross-sectional area, it exhibits less mechanical stress capacity compared to fasteners with a circular cross-section, and at the same time also presents a lower load capacity on the thread fillet rolled into the substrate, since it has a smaller contact area. Another characteristic of trilobular self-tapping fasteners is a low installation torque, which facilitates assembly and allows for easier substrate rolling.

[0010]

[0007] However, trilobular self-tapping fasteners, due to their geometry, create a lower shear torque on the female thread and generate a reduced joining force compared to fasteners with a circular cross-section, resulting in the need for oversizing the joint, in addition to presenting a more difficult manufacturing process due to the need for an asymmetrical fastener profile.

[0011]

[0008] An example of the state of the art is Chinese document CN215257251 which discloses a self-tapping screw comprising a screw body fitted with a clamping seat, wherein the outer circumference of the screw body is provided with triangular (trilobular) threads.A plurality of entry tooth layers are arranged on the outer circumference of the screw threading head end body. Three internal grooves are uniformly formed in the screw threading head end body along the entry teeth, where each internal groove has a curved triangular surface groove shape, so that the screw threading head end body has a more compact structure, the service life of the head end body is extended, the resistance to back threading is reduced, such that chips are discharged through the axial grooves on the three large arc surfaces, and finally, the resistance to loosening after locking is increased.

[0012]

[0009] With the aim of promoting technological advancement, based on the state of the art, this document aims at new thread profile geometries for a self-tapping fastener, in which its cross-section is completely circular and which results in low torque for insertion into the substrate, increased maximum joint torque and increased bonding force, improving the bond between materials, which advantageously increases the application window of the self-tapping fastener.

[0013]

[0010] Thus, an objective of the present invention is to provide a self-tapping fastener having a thread profile in which the thread fillets are asymmetrical, being straight on one side and having a concave relief on the other.

[0014]

[0011] Another objective of the present invention is to provide a self-tapping fastener equipped with a tip in which the first threads follow a graduation of the external diameter until reaching the main threads of the fastener.

[0015]

[0012] Another objective of the present invention is to provide a self-tapping fastener in which the first threads have their maximum external diameter interrupted at at least one point on the radial perimeter of the fastener. Optionally, the interruptions of the maximum external diameter of the threads may be arranged linearly and longitudinally in the fastener or may be arranged radially.

[0016]

[0013] Optionally, the first thread fillets also include grooves whose depth may be constant or follow a gradual variation towards the fastener head. Also optionally, the grooves may be arranged linearly in a longitudinal section of the fastener or may be arranged helically in relation to the fastener axis.

[0017]

[0014] Schematic figures of a particular embodiment of the invention will be presented, whose dimensions and proportions are not necessarily the actual ones, since the figures are only intended to didactically present its various aspects, whose scope of protection is determined only by the scope of the appended claims.

[0018] BRIEF DESCRIPTION OF THE FIGURES

[0019]

[0015] Figure 1 illustrates a schematic figure of a fastener (1) showing the head (2), circular rod (3) and the main (30) and secondary (31) threads.

[0016] Figure 2 illustrates a cutaway and sectional view of the fastener (1) showing a thread (34) comprising sides A (34A) and B (34B) in an asymmetrical manner.

[0020]

[0017] Figure 3 illustrates a partial view of the fastener (1) showing the secondary (31) and the inclination (a) of the thread entry of the outer diameter of each thread (34).

[0021]

[0018] Figure 4 illustrates a partial view of the fastener (1) showing the main (30) and secondary (31) threads and a relief (4).

[0022]

[0019] Figure 5 illustrates a partial view of the fastener (1) showing another way of performing the relief (4).

[0023]

[0020] Figure 6 illustrates a partial view of the fastener (1) showing a set of grooves (35) arranged in the main (30) and secondary (31) threads and a relief (4).

[0024]

[0021] The subject matter of this document will be better understood in light of the detailed description that follows in its preferred, but not limiting, embodiment, which is illustrated by the schematic drawings attached.

[0025] DETAILED DESCRIPTION

[0026]

[0022] According to the attached figures, the present invention relates to a new thread profile geometry of a self-tapping fastener. Thus, according to figure 1, the fastener (1) comprises a head (2) a circular rod (3) provided with a main thread (30), a secondary thread (31) disposed at an end (32) opposite the head (2).

[0027]

[0023] Figure 2 illustrates a thread (34) that makes up the main threads (30) and the secondary threads (31), such that said thread (34) comprises sides A (34A) and B (34B) asymmetrical to each other, wherein side A (34A) has a straight face (340) and a first radius (341) facing the head (2) of the fastener (1), while side B (34B) has a first section (342) followed by a relief region (343) and a second radius (344), in the direction of the circular rod (3) and which are facing the tip of the fastener (1).

[0028]

[0024] The straight face (340) of side A (34A) comprises an angle of inclination that varies between 10 and 20 e with respect to the central axis (C) of the fillet (34), preferably, the inclination of the straight face (340) is 15 e The first radius (341) is defined by the thread pitch / 3.33. With respect to side B (34B), the first section (342) comprises a radius with a value equal to the thread pitch of the fastener (1), while the relief region (343) comprises a straight segment with a slope of 15 e with respect to the central axis (C) of the thread (34) and the second radius (344) comprises a value equal to 0.1875 times the thread pitch of the fastener (1). Thus, the values ​​of the first section (342) and the second radius (344) will be defined according to the gauge of the fastener (1).

[0029]

[0025] As illustrated by figure 3, the end (32) of the fastener (1) where the secondary threads (31) are located, comprises a thread entry inclination (a) of the outer diameter of each thread (34), where this inclination (a) varies between 6 and 12 s , preferably 9 e with regard to the external diameter of the threads (34) of the main threads (30) of the fastener (1). Also preferably, the secondary threads (31) comprise up to five threads (34), however, the number of threads (34) may depend on factors such as design, fastener gauge, among other variables. In this way, advantageously, the fastener (1) ensures a gradual delamination of the material when applied to a substrate, reducing the initial installation torque.

[0030]

[0026] In a preferred embodiment, according to figures 3 and 4, the threads (34) of the secondary threads (31) are interrupted by at least one relief (4) disposed on the radial perimeter of the fastener (1) and comprises an inverted “V” configuration, while the secondary thread (31) comprises a “V” configuration. Said relief (4) comprises a depth that varies between the outer diameter of the main thread (30) and the outer diameter of the circular rod (3), i.e., the relief (4) can vary the outer diameter of each thread (34) disposed on the secondary thread (31).

[0031]

[0027] In another embodiment, according to figure 5, the relief (4) comprises a straight “I” configuration, thus, the relief (4) is arranged in a linear and longitudinal manner, in the direction of the head (2) of the fastener (1).

[0032]

[0028] Preferably, the fastener (1) comprises three relief regions (4), but it will be understood that the number of reliefs (4) arranged in the radial section of the fastener (1) may vary according to the design, the gauge of the fastener, among other variables.

[0033]

[0029] Optionally, the relief (4) may extend to the threads (4) of the main threads (30). Similarly, as illustrated in figures 6 and 7, optionally, each thread (34) of the secondary thread (31) comprises a set of grooves (35), which may be arranged linearly and longitudinally in relation to the axis of the fastener (1) or may be arranged helically in relation to the axis of the fastener (1). It will be understood that, in either embodiment, the set of grooves (35) may extend to the threads (34) of the main threads (30).

[0034]

[0030] In this way, when the fastener (1) is installed on the substrate, a gradual delamination of the material occurs. With reduced friction due to less material drag on the surface of the fastener (1), a characteristic obtained through the combination of the configuration of side B (34B) of each thread (34) with the reliefs (4) arranged, preferably at the end (32) where the secondary threads (31) are located. For better efficiency, optionally, the fastener (1) is provided with grooves (35) arranged in the threads (34), which reduces the necessary installation torque and improves the seating of the delaminated material, generating greater force in the joint created after installation. Thus, through these characteristics, the application window of the self-tapping fastener (1) is increased.

[0035]

[0031] A person skilled in the art will readily perceive, from the description and the drawings provided, various ways of carrying out the invention without departing from the scope of the appended claims.

Claims

MODIFIED CLAIMS Received by the International Secretariat on February 18, 2026 (18.02.2026) 1- SELF-TAPPING FASTENER, wherein the fastener (1) comprises a head (2), a circular rod (3) provided with a main thread (30), a secondary thread (31) disposed at an end (32) opposite the head (2); the threads, main (30) and secondary (31) comprise threads (34) provided with asymmetrical sides A and B (34A and 34B), wherein side A (34A) is provided with a straight face (340) and a first radius (341), while side B (34B) is provided with a first section (342) followed by a relief region (343) and a second radius (344), in the direction of the circular rod (3); the secondary threads (31) comprise a thread entry inclination (a) on the outer diameter of each thread (34) until reaching the outer diameter of the threads (34) of the main threads (30) of the fastener (1);the threads (34) of the secondary threads (31) being interrupted by at least one relief (4) disposed on the radial perimeter of the fastener (1), characterized by the straight face (340) of side A (34A) comprising an angle of inclination that varies between 10 and 20° in relation to the central axis (C) of the thread (34) and the first radius (341) being defined by the thread pitch / 3.33; the first section (342) comprising a radius with a value equal to the thread pitch of the fastener (1), the relief region (343) comprising a straight segment with an inclination of 15° in relation to the central axis (C) of the thread (34) and the second radius (344) comprising a value equal to 0.1875 times the thread pitch of the fastener (1); the inclination (a) of the thread entry of the outer diameter of each thread (34) of the secondary thread (31) varies between 6 and 12° in relation to the outer diameter of the threads (34) of the main threads (30) of the fastener (1).; DECLARATION ACCORDING TO ARTICLE 19(1) 2- SELF-TAPPING FASTENER, according to claim 1, characterized in that the straight face (340) of side A (34A) of the fillet (34) is facing the head (2) and comprises an angle of inclination of 15° in relation to the central axis (C) of the fillet (34). 3- SELF-TAPPING FASTENER, according to claim 1, characterized in that the inclination (a) of the thread entry of the outer diameter of each thread (34) of the secondary thread (31) is 9 o with respect to the outer diameter of the threads (34) of the main threads (30) of the fastener (1). 4- SELF-TAPPING FASTENER, according to claim 1, characterized in that the secondary thread (31) comprises up to five thread pitches in the direction of the head (2) of the fastener (1) at an inclination of 9 o . 5- SELF-TAPPING FASTENER, according to claim 1, characterized in that the relief (4) comprises an inverted “V” configuration, while the secondary thread (31) comprises a “V” configuration. 6- SELF-TAPPING FASTENER, according to claim 5, characterized in that the relief (4) comprises a straight “I” configuration. 7- SELF-TAPPING FASTENER, according to claims 1, 5 and 6, characterized by the relief (4) comprising a depth that varies between the outer diameter of the main thread (30) and the outer diameter of the circular shank (3). 8- SELF-TAPPING FASTENER, according to claims 5, 6 and 7, characterized by the relief (4) advancing to the threads (34) of the main thread (30). 9- SELF-TAPPING FASTENER, according to claim 1, characterized in that each thread (34) of the secondary thread (31) comprises a set of grooves (35). DECLARATION ACCORDING TO ARTICLE 19(1) 10- SELF-TAPPING FASTENER, according to claim 9, characterized in that the set of grooves (35) is arranged linearly and longitudinally in relation to the axis of the fastener (1). 11- SELF-TAPPING FASTENER, according to claim 9, characterized in that the set of grooves (35) is helically arranged in relation to the axis of the fastener (1). 12- SELF-TAPPING FASTENER, according to claim 9, characterized by the set of grooves (35) extending to the threads (34) of the main threads (30). DECLARATION ACCORDING TO ARTICLE 19(1)

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