Self-tapping fastener for use on plastic or similar materials.

Description

1 / 8 Self-tapping fastener for use on plastic or similar materials. FIELD OF APPLICATION

[001] This document refers to a new thread profile geometry for fasteners intended for application in plastics or similar materials, whereby said geometry comprises an end with thread fillets that vary in external diameter, designed to reduce installation torque along the insertion into the substrate. Advantageously, the first thread fillets have a wavy profile that generates relief zones, decreasing contact with the plastic material, which facilitates controlled thread formation, reduces the effort required during installation and provides greater bond strength between the fastener and the substrate. STATE OF THE ART

[002] 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.

[003] Among the fastener options available on the market are screws designed for use in plastic and / or similar materials, which are designed to fasten to a substrate without causing excessive deformation of the material as they are applied. These screws have specific geometric characteristics, such as sharp threads and a reduced thread pitch, in order to form the thread directly on the substrate during the insertion process. However, despite Petition 870240109398, dated 12 / 20 / 2024, page 13 / 26 2 / 8 of these fixators are widely used, but they have recurring problems that compromise their performance and limit their applicability.

[004] A peculiar characteristic of these fasteners is the thread geometry, which has a specific profile that, when inserted, facilitates penetration into the material, minimizing effort during installation. The use of these geometries helps the industry reach new levels in assemblies, 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.

[005] The state of the art is constantly improving the geometries related to 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 joining force generated for a fastener in a self-tapping application.

[006] An example of the state of the art is the Brazilian document PI9806235, which describes a screw produced by cold rolling with a self-grooving thread, where the flanks of the thread have an inward bend, creating external and internal flank angles with significant differences. Although the geometry aims to facilitate screwing into plastic materials, it can result in difficulties during installation, especially in more rigid substrates, due to increased friction and possible material deformations. In addition, the end face of the thread, with an oblique cutting edge, can compromise the uniformity of the fastening and generate excessive wear, suggesting the need Petition 870240109398, dated 12 / 20 / 2024, page 14 / 26 3 / 8 of improvements in geometry to optimize performance and reduce failures in the tapering process.

[007] Another example of the state of the art is document WO2019238991 which describes a screw that includes a conical section and a threaded shaft with asymmetrical flanks. The screw incorporates a guide thread with an increasing outer diameter, which helps to distribute stress evenly and minimizes heat generation during the threading process. In addition, the design includes notches along the thread that reduce friction and increase the screw's ability to resist loosening. However, by optimizing the screw geometry for different types of materials, a more complex geometry is obtained, which can increase the difficulty of manufacturing and quality control, as well as making the installation process more challenging, especially on plastic substrates with different mechanical properties.

[008] Another very common problem in the state of the art is related to high installation torque. Conventional fasteners tend to generate significant friction between the threads and the plastic substrate, mainly due to the lack of relief zones in the thread geometry. This excessive friction results in greater stress during application, increasing the risk of failures during the fastening process, such as material deformation or breakage of the formed thread.

[009] Furthermore, currently available fasteners often do not consider the ability of the plastic material to be moved in a controlled manner during insertion. Because plastics are less rigid materials, with lower mechanical strength and a tendency to creep under pressure, the application of fasteners with inadequate geometries can generate excessive local deformations, weakening the formed thread and compromising the mechanical strength of the fastener, resulting in inefficient engagement between the fastener and the plastic substrate. Petition 870240109398, dated 12 / 20 / 2024, page 15 / 26 4 / 8

[010] Another common problem in the state of the art is premature wear of the formed thread. In conventional fasteners, the thread geometry is not designed to optimize contact with the plastic substrate, which causes stress concentration points and accelerated wear during application or under continuous loads. This reduces the service life of the fastener, especially in applications subject to vibration, cyclic stresses, or temperature changes.

[011] Furthermore, traditional fasteners have a limited application window, meaning their performance tends to be unstable when used on plastics with different mechanical properties, such as high- or low-density plastics. The lack of versatility in thread geometry makes it difficult to achieve consistent performance, restricting their application to a small number of materials and compromising competitiveness in sectors that use various types of plastic substrates.

[012] Finally, the absence of solutions that incorporate relief regions and more advanced thread profiles, such as corrugations or controlled variations in thread diameter, prevents an efficient reduction of insertion torque. Excessive direct contact between the thread fillets and the plastic substrate generates a considerable increase in friction, hindering controlled thread formation and requiring additional effort during installation.

[013] With the aim of promoting technological advancement, based on the state of the art, this document aims at new thread profile geometries for fasteners intended for application in plastics or similar materials, such that said geometry comprises an end equipped with thread fillets of varying diameter, designed to reduce the installation torque during insertion into the substrate.

[014] Thus, an objective of the present invention is to provide a fastener with a new thread profile geometry, comprising Petition 870240109398, dated 12 / 20 / 2024, page 16 / 26 5 / 8 thread fillets with variable diameter in the same thread pitch. Thus, the first fillets are designed so that the thread increases and decreases at specific points along the rotation, creating regions of variable external diameter that promote ideal delamination in the substrate and, almost simultaneously, relieve the initial torque, thus ensuring better accommodation of the displaced material, since the thread deforms the plastic material to flow around the thread fillet.

[015] This innovative configuration results in less effort during installation, increased installation speed, widening the application window and increasing fastener performance.

[016] Another objective of the present invention is to provide a fastener that can be configured in single helix or double helix versions. In the single helix configuration, the area dedicated to thread formation corresponds to twice the thread pitch, while in the double helix configuration, this area is equivalent to once the thread pitch, ensuring optimized performance. These characteristics make the fastener particularly suitable for applications in low or high density plastics, as well as in equivalent materials, where torque reduction and increased bonding strength are essential factors.

[017] Schematic figures of a particular embodiment will be presented, whose dimensions and proportions are not necessarily the actual ones, as the figures are only intended to didactically present its various aspects, whose scope of protection is determined only by the scope of the attached claims. BRIEF DESCRIPTION OF THE FIGURES

[018] Figure 1 illustrates a schematic figure of a fastener (1) showing the head (2), circular rod (3) with a set of thread fillets (30) configured by means of a forming region (RF) and a support region (RS). Petition 870240109398, dated 12 / 20 / 2024, page 17 / 26 6 / 8

[019] Figure 2 illustrates a comparative graph between the thread profile (30) in relation to two state-of-the-art examples.

[020] Figure 3 illustrates a graph demonstrating a variation of the increasing external diameter until it reaches the transition point and arrives at the nominal diameter of the support region (RS).

[021] Figure 4 illustrates a graph demonstrating a decreasing variation in the external diameter until it reaches the transition point and arrives at the nominal diameter of the support region (RS).

[022] Figure 5 illustrates a graph demonstrating a stable variation in the external diameter, maintaining the same amplitudes until reaching the transition point and arriving at the nominal diameter of the support region (RS).

[023] 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. DETAILED DESCRIPTION

[024] According to the attached figures, the present invention relates to a new thread profile geometry of a self-tapping fastener intended for application in plastics or similar materials.

[025] Thus, as illustrated in figure 1, the fixator (1) comprises a head (2) and a circular rod (3) equipped with a set of threaded fillets (30) configured by means of a forming region (RF) and a support region (RS), wherein the forming region (RF) is disposed at the proximal end of the tip of the fixator (1), while the support region (RS) is disposed subsequently to the forming region (RF) following in the direction of the head (2). Petition 870240109398, dated 12 / 20 / 2024, page 18 / 26 7 / 8

[026] Preferably the fastener (1) comprises a single helix, however, such fastener (1) may comprise a double helix, so that in the embodiment of the invention, considering a single helix, the area dedicated to thread formation, referred to in this document as the forming region (RF), corresponds to twice the thread pitch, while in the embodiment of the invention, considering a double helix, the thread formation area, the forming region (RF), this area is equivalent to once the thread pitch, ensuring the performance of the fastener (1) in either embodiment of the invention.

[027] As illustrated by figure 2, fasteners comprising the same thread profile in both the forming and supporting regions are commonly found in the state of the art, as illustrated by the green dashed line or the lower dashed line. Also in the state of the art, seeking performance solutions, some fasteners comprise a forming region different from the supporting region, as illustrated by the blue dashed line or the upper dashed line, where the fastener, at the beginning of the thread profile, has the largest diameter, continuing throughout the forming region until it meets the supporting region.

[028] However, still according to figure 2, in its preferred embodiment of the invention, as illustrated by the red continuous line or the intermediate continuous line, the thread fillet (30) of the forming region (RF) comprises at least two variations in the external diameter in the same thread pitch of the fastener (1), wherein the amplitude of the variation is 2 to 5% in relation to the external diameter of the thread fillets (30) of the support region (RS).

[029] Thus, in the first thread fillets (30), the profile has its outer diameter increased in order to deform a greater amount of plastic material to flow around the thread fillets (30). However, still in the same thread pitch, the profile has its outer diameter reduced to the same diameter as the support region (RS), creating relief points, Petition 870240109398, dated 12 / 20 / 2024, page 19 / 26 8 / 8 promoting an accommodation of the initially deformed material, as well as promoting a reduction in torque and an increase in the insertion speed of the fastener (1), without compromising the bond strength between the substrate and said fastener (1).

[030] It will be understood that variations in the external diameter of the thread profile (30) that are arranged in the forming region (RF) may comprise an increasing, decreasing or stable configuration.

[031] In other words, the increasing variation in the external diameter means that the amplitudes of this variation follow an upward trend until reaching the transition point and arriving at the nominal diameter of the support region (RS), as illustrated in figure 3. Similarly, as shown in figure 4, the decreasing variation in the external diameter means that the amplitudes of this variation follow a downward trend, while the stable variation in the external diameter maintains the same amplitudes until reaching the transition point and arriving at the nominal diameter of the support region (RS), as shown in figure 5.

[032] In this way, through these self-tapping fastener (1) characteristics, it expands the range of applications, and can be used on plastic or similar materials of low or high density.

[033] 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. Petition 870240109398, dated 12 / 20 / 2024, p. 20 / 26

Claims

1 / 1 CLAIMS 1- SELF-TAPPING FASTENER APPLIED TO PLASTIC OR SIMILAR MATERIALS, wherein the fastener (1) comprises a head (2) and a circular rod (3) provided with a set of threaded grooves (30) configured by means of a forming region (RF) and a support region (RS), wherein the forming region (RF) is disposed at the proximal end of the fastener tip (1), while the support region (RS) is disposed subsequently to the forming region (RF) following in the direction of the head (2), characterized in that the threaded groove (30) of the forming region (RF) comprises at least two variations in the external diameter in the same thread pitch of the fastener (1), wherein the amplitude of the variation is from 2 to 5% in relation to the external diameter of the threaded grooves (30) of the support region (RS). 2- SELF-TAPPING FASTENER APPLIED TO PLASTIC OR SIMILAR MATERIALS, according to claim 1, characterized in that the variations in the external diameter of the thread profile (30) arranged in the forming region (RF) comprise an increasing, decreasing or stable configuration. 3- SELF-TAPPING FASTENER APPLIED TO PLASTIC OR SIMILAR MATERIALS, according to claim 1, characterized in that the forming region (RF) is arranged in the first two thread pitches of the fastener (1), starting from the tip of the fastener (1). 4- SELF-TAPPING FASTENER APPLIED TO PLASTIC OR SIMILAR MATERIALS, according to any one of claims 1 to 3, characterized in that the fastener (1) comprises a double helix. Petition 870240109398, dated 12 / 20 / 2024, page 21 / 26

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