FASTENER FOR PREVENTING THE ASSEMBLY PROBLEMS CAUSED BY MISALIGNMENT

Abstract

A fastener is provided. The fastener, in the assembly of fasteners, prevents cross threading that occurs when an externally threaded fastener is threaded into a female fastener that is not axially aligned, and the method of production thereof is also provided. The fastener includes a shaft, a head, and a catching section.

Claims

1. A fastener, comprising; a shaft, wherein the shaft comprises two parts that a body section and a coupling section and has a threaded portion comprising more than one thread with first and second minor diameters and first and second major diameters, and the threaded portion extends helically around an outer surface of the shaft starting at any level, a head, wherein the head transfers torque applied by a tool to the shaft for tightening and loosening, a catching section, wherein the catching section is adjacent to the shaft and guides the fastener, wherein the threaded portion extending helically around the shaft runs continuously from the body section to the coupling section of the shaft, and the threaded portion in the coupling section has threads, wherein a difference between the second minor diameter and the second major diameter decreases gradually towards the catching section.

2. The fastener according to claim 1, wherein the coupling section of the shaft has a curved surface.

3. The fastener according to claim 2, wherein the coupling section of the shaft has the curved surface tangent to the body section of the shaft, at an intersection of a plane extending perpendicular to a longitudinal axis of the fastener at a level where the body section ends and an end of said body section.

4. The fastener according to claim 3, wherein the curved surface of the coupling section of the shaft denotes an arc of a circle, a center of the curved surface of the coupling section is located on a plane extending perpendicular to a longitudinal axis of the fastener from a level where the body section of the shaft ends and outside a boundary of the shaft.

5. The fastener according to claim 1, wherein the catching section comprises a first portion and a second portion.

6. The fastener according to claim 5, wherein the second portion of the catching section has a curved surface.

7. The fastener according to claim 6, wherein the second portion of the catching section has the curved surface tangent to the first portion of the catching section at an intersection of a plane extending perpendicular to a longitudinal axis of the fastener at a level where the first portion of the catching section ends and an end of the first portion of the catching section ends.

8. The fastener according to claim 6, wherein the curved surface of the second portion of the catching section denotes an arc of a circle, a center of the curved surface of the second portion is located on a plane extending perpendicular to a longitudinal axis of the fastener at a level where the first portion of the catching section ends and within a boundary of the catching section.

9. The fastener according to claim 1, wherein a first diameter of the body section of the shaft is larger than a second diameter of a first portion of the catching section.

10. The fastener according to claim 1, wherein a length of the coupling section of the shaft is between 0.6 and 6.0 times a length of the catching section.

11. The fastener according to claim 1, wherein a length of a second portion of the catching section is between 0.1 and 3 times a thread pitch.

12. A fastener system configured to prevent cross threading, comprising; a female fastener, wherein the female fastener has a center hole where a continuous helical threaded portion with threads extends along the hole towards a longitudinal axis of the female fastener, and a male fastener, wherein the male fastener engages into the female fastener, wherein the male fastener comprises: a shaft, wherein the shaft comprises two sections that a body section and a coupling section, and has a threaded portion comprising more than one thread with first and second minor diameters and first and second major diameters, and the threaded portion extends helically around an outer surface of the shaft starting from any level, a head, wherein the head transfers torque applied by a tool to the shaft for tightening and loosening, a catching section, wherein the catching section is adjacent to the shaft and guides the fastener, wherein; the threaded portion extending helically around the shaft runs continuously from the body section to the coupling section of the shaft, and the threaded portion in the coupling section has threads, wherein a difference between second minor diameter and second major diameter decreases gradually towards the catching section.

13. The fastener system according to claim 12, wherein the coupling section of the shaft has a curved surface.

14. The fastener system according to claim 13, wherein the coupling section of the shaft has the curved surface tangent to the body section of the shaft at an intersection of a plane extending perpendicular to a longitudinal axis of the fastener at a level where the body section ends and an end of the body section.

15. The fastener system according to claim 13, wherein the curved surface of the coupling section of the shaft denotes an arc of a circle, a center of the curved surface of the coupling section is located on a plane extending perpendicular to a longitudinal axis of the fastener from a level where the body section of the shaft ends and outside a boundary of the shaft.

16. The fastener system according to claim 12, wherein the catching section comprises a first portion and a second portion.

17. The fastener system according to claim 16, wherein the second portion of the catching section has a curved surface.

18. The fastener system according to claim 17, wherein the second portion of the catching section has the curved surface tangent to the first portion of the catching section at an intersection of a plane extending perpendicular to a longitudinal axis of the fastener at a level where the first portion of the catching section ends and an end of the first portion of the catching section ends.

19. The fastener system according to claim 17, wherein the curved surface of second portion of the catching section donates an arc of a circle, a center of the curved surface of second portion is located on a plane extending perpendicular to a longitudinal axis of the fastener at a level where the first portion of the catching section ends and within boundaries of the catching section.

20. The fastener system according to claim 12, wherein a first diameter of the body section of the shaft is larger than a second diameter of a first portion of the catching section.

21. The fastener system according to claim 12, wherein a length of the coupling section of the shaft is between 0.6 and 6.0 times a length of the catching section.

22. The fastener system according to claim 12, wherein a length of a second portion of the catching section is between 0.1 and 3 times a thread pitch.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] FIG. 1 is a front view of the fastener according to the invention.

[0040] FIG. 2 is a front view of the shaft portion of the fastener according to the invention in blank form (without the threaded portion).

[0041] FIG. 3 is an enlarged view of the Z-section of the fastener according to the invention shown in FIG. 2.

[0042] FIG. 4 is a view of the vertical cross-sectional area of the fastener according to the invention.

[0043] FIGS. 5A-5E are step by step views of the positions of the fastener according to the invention during assembly, with respect to the female fastener.

[0044] FIG. 6 is a front view of a fastener system comprising the fastener according to the invention and the female fastener into which it passes, showing the entry position of the fastener according to the invention to the female fastener.

[0045] FIG. 7 is a representative view of the fastener according to the invention with the shaft part in blank form (without the threaded portion), showing the center points and radii of the circles to which, the arcs formed by the curved surfaces in the coupling section and the catching section belong.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] The present invention relates to a fastener having a shaft (13) and specially designed coupling and catching sections at the end, which, during assembly, can align its axis with the axis of the other fastener to which it connects and prevent cross threading.

[0047] In the detailed description given below, each part of the fastener represented by reference numerals and their interrelationships are explained in detail in order to make the invention more understandable, with reference to the figures in which the details of the preferred embodiments of the invention are shown schematically.

[0048] In FIG. 1, where the front view of the fastener (10) according to the invention is given, the said fastener (10) is an externally threaded fastener such as a bolt or screw and comprises a head (11) that provides the torque applied rotationally by a standard bit or wrench for the assembly transferred to the fastener (10) in an appropriate manner, a shaft (13) extending from the bearing surface of the head (12) towards the end (16) and consisting of two parts, a threaded portion (14) extending helically on the outside of the shaft, and a catching section (16) located adjacent to the shaft (13) and guiding the fastener (10). The structure of the threads in the threaded portion (14) starting from any level of the shaft (13) and extending continuously helically on its outer surface can be of any standard or special form such as whitworth and trapezoidal.

[0049] As can be seen in FIG. 2, the shaft (13) consists of two parts, the body section (13a) and the coupling section (13b). In FIG. 2, as seen from the front view in which the blank form of the fastener shaft (13), in other words, the shaft (13) where the threaded portion (14) extends continuously helically around the outer surface of the shaft (13) not formed is shown, the body section (13a) extends axially towards the coupling section (13b) of the shaft from the bearing surface of the head (12) and it may be cylindrical or of any particular geometric structure, but according to a preferred embodiment of the invention, it is cylindrical. The coupling section (13b), which is adjacent to the body section (13a) of the shaft, has a curved surface. As it can be understood more easily in FIG. 3, where the enlarged view of the part A shown in FIG. 2 is given, the curved surface of the coupling section (13b) of the shaft is tangent to the body section (13a) of the shaft, at the intersection of the plane extending perpendicular to the longitudinal axis of the fastener (X.sub.1) at the level where the body section ends (17) and the end of the said body section (17).

[0050] Adjacent to the coupling section (13b) is the catching section of the fastener (16). The catching section of the fastener (16) according to the invention is also the end of the fastener. The coupling section (13b) and the catching section (16) are separated from each other by the boundary line (18). The fastener coupling section (13b) is located between the end of the shaft body section (17) and the boundary line (18). The outer surface of the coupling section (13b) also extends curved from the end of the body section (17) of the shaft towards the boundary line (18).

[0051] The catching section (16) of the fastener (10) according to the present invention also consists of two parts. The first portion of the catching section (16a), located adjacent to the boundary line (18) between the catching section (16) and the coupling section (13b), is preferably cylindrical, and the second portion (16b) is located adjacent to the first section (16a). The diameter (d.sub.1) of the body section (13a) of the shaft is larger than the diameter (d.sub.2) of the first portion of the catching section (16a). The second portion of the catching section (16b) has a curved surface as in the coupling section (13b). This curved surface is tangent to the first portion (16a) of the catching section (16) at the intersection of the plane extending perpendicular to the longitudinal axis (X.sub.1) of the fastener at the level where the first portion of the catching section (19) ends and the end of the first portion of the catching section (19). The curved surface of the second portion (16b) of the catching section ends at the level (20) where the catching section (16) of the fastener ends, in other words, at the level of the catching section (16) farthest from the head (11) of the fastener (16) according to the invention.

[0052] As seen in FIG. 3, the length of the coupling section (d.sub.x) in the shaft of the fastener (13) according to the invention is the distance between the level (17) where the body section of the shaft (13a) ends and the boundary line (18). The length (d.sub.y) of the catching section (16) of the fastener (10) according to the invention is the distance between the boundary line (18) between the coupling section (13b) and the catching section (16) and the level (20) where the catching section of fastener ends.

[0053] In one embodiment of the present invention, the length of the coupling section of the fastener (d.sub.x) is 0.6 to 6.0 times, preferably 0.8 to 5.0 times, and more preferably 1.1 to 4.5 times the length of the catching section (d.sub.y).

[0054] In another embodiment of the present invention, the length of the second portion of the catching section (d.sub.z) of the fastener is the distance between the level (19) where the first portion of the catching section ends, and the level (20) where the catching section of fastener (16) ends. According to a preferred embodiment of the present invention, the length of the second portion of the catching section (d.sub.z) is 0.1 to 3 times, preferably 0.2 to 2.5 times, more preferably 0.5 to 2 times the thread pitch (p).

[0055] In one embodiment of the present invention, FIG. 4 shows the minor diameters (d.sub.1, d.sub.2), major diameters (d.sub.1, d.sub.2) and thread heights (h.sub.1, h.sub.2) of the threaded portion (14) at the body section (13a) and the coupling section (13b) of the shaft extending axially along the longitudinal axis (X.sub.1) of the fastener (10) towards the catching section (16), starting from the bearing surface of the head (12). According to one embodiment of the invention, if the body section (13a) of the shaft is preferably cylindrical, the minor diameter (d.sub.1) and the major diameter (d.sub.1) are constant along the threaded portion (14) extending continuously helically starting from any level around the outer surface of the body section (13a) of the shaft. In case the minor diameter (d.sub.1) and major diameter (d.sub.1) in the threaded portion (14) of the shaft in the body section (13a) are the same along the threaded portion (14) in the body section (13a), the difference minor diameter (d.sub.1) and the major diameter (d.sub.1), therefore the thread height (h.sub.1), remains constant along the threaded portion (14) in the body section (13a). Accordingly, the threaded portion in this section (13a) may consist of completely-formed threads (14a).

[0056] According to another embodiment of the invention, in case body section (13a) of the shaft has a special form such as triple lobular, four lobular, or elliptical, the difference between the minor diameter (d.sub.1) and the major diameter (d.sub.1) may vary along the threaded portion (14) extending helically (14) around the outer surface of the body section of the shaft (13a). If this is the case, the thread height (h.sub.1) may also differ along the threaded portion (14) extending helically around the outer surface of the body section of the shaft (13a). Accordingly, the threads (14a) in the threaded portion of the body section (14) of the shaft may be in completely-formed form in some parts of the threaded portion (14) and incompleted form in some other parts.

[0057] The coupling section (13b) of the shaft is located adjacent to the body section (13a) of the shaft. The threaded portion (14), which extends helically around the outer surface of the shaft body section (13a) starting from any level of the shaft (13), continues to extend helically around the outer surface of the coupling section (13b) of the shaft in an uninterrupted manner. However, in the threaded portion extending helically around the coupling section (13b) of the shaft, the difference between the the minor diameter (d.sub.2) and the major diameter (d.sub.2) and therefore, the thread height (h.sub.2), gradually decreases starting from any level of the coupling section (13b), preferably from the level where the body section of the shaft ends (17), and the threaded portion (14) ends at the point (15) where this difference is zero (FIG. 1). There are incompleted threads (14b) in the threaded portion (14), which extends continuously helically around the coupling section (13b), where the difference between the minor diameter (d.sub.2) and the major diameter (d.sub.2), and therefore, the thread height (h.sub.2) gradually decreases.

[0058] However, according to the present invention, the pitch value in the threaded portion (14) that extends continuously helically on the outer surface of the fastener shaft (13) is the same along the threaded portion (14), that is, in both parts (13a and 13b) of the shaft.

[0059] In the preferred embodiment of the present invention, the fastener is a male fastener (10) with an externally threaded form, and the fastener into which the said fastener (10) engages in order to establish a connection, is an internally threaded female fastener (40) with a continuously helically extending threaded portion (43) comprising threads (44) extending towards the center of the fastener through the hole (42) in the middle of said fastener.

[0060] According to another embodiment of the invention, the fastener into which the fastener according to the invention (10) is engaged in order to establish a connection may be a female fastener having a non-threaded hole. However, the fastener (10) according to the invention can also be assembled on a pre-drilled or non-drilled workpiece to form a connection.

[0061] The fact that the catching section of the male fastener (10) according to the invention is composed of the first portion (16a) in preferably cylindrical form and the second portion (16b) which is curved ensure the axis (X.sub.1) to enter the female fastener at a suitable angle to be self-aligning with the axis of the female fastener (X.sub.2), when the longitudinal axis (X.sub.1) of the said fastener is not aligned with the longitudinal axis (X.sub.2) of the female fastener (40) into which it passes. However, in the fastener (10) according to the invention, the coupling section (13b), which has a threaded portion (14) extending continuously helically around its curved surface and comprising incompletely formed (14b) threads, where the difference between the minor diameter (d.sub.2) and the major diameter (d.sub.2) gradually decreases, ensures that the male fastener (10) according to the invention becomes coaxial with the female fastener (40) and goes forward in the female fastener (40) without cross threading. As an example, the positions of the said fastener (10) relative to an internally threaded female fastener (40) are shown in FIGS. 5A-5E step by step during the assembly of the male fastener (10) according to the invention. Accordingly, in more detail, in the assembly of the male fastener (10) according to the invention, which enters an internally threaded female fastener (40) at an appropriate angle thanks to the catching section (16), as the torque applied fastener (10) continues its rotational movement in the direction (R) shown in FIGS. 5B-5E, the incompleted threads (14b) in the coupling section (13b) also cam over threads of the female fastener (41) without cross threading and the fastener (10) coaxially aligns with the female fastener (40). Thus, a proper connection between the two fasteners (10, 40) is achieved. While the rotational movement (R) of the fastener (10) continues, the threads (14a) in the body section of the shaft (13a) also couple the threads (44) of the female fastener properly, and thanks to the proper engagement of the threads of the two fasteners, the male fastener (10) can easily go forward inside the female fastener (40) and the desired connection is achieved (FIGS. 5D-5E).

[0062] In another embodiment of the present invention, as seen in the connection system (50) according to the invention shown in FIG. 6, without the longitudinal axes of the fasteners (X.sub.1 ve X.sub.2) being aligned, as the male fastener (10) continues to move rotationally after entering the hole (42) from one end (40a) of the female fastener (40) to establish a connection, with the level of the boundary line (18) of the fastener (10) being in line with the center of the first completely-formed thread (41a) of the female fastener (40) it comes across and contacts, or further towards the other end of the female fastener (40b), the incompleted threads (14b) in the coupling section (13b) cam over the threads (44) in the female fastener and the fastener (10) moves forward without cross threading. The male fastener (10) coaxially aligns with the female fastener (40) as the incompleted threads (14b) in the coupling section cam over the threads (44) of the female fastener.

[0063] The catching section (16) in the fastener according to the invention is designed to ensure that the level of the boundary line (18) to be at a position that allows for the male fastener (10) to be coaxially aligned with the female fastener (40) as the incompleted threads (14b) at the coupling section (13b) cam over the threads (44) in the female fastener when the male fastener (10) enters the female fastener (40). The female fastener (40) has a continuous helical threaded portion (43) in which the threads (44) extending towards the longitudinal axis (X.sub.2) of the said fastener (40) are located along the hole (42) in the middle of said fastener (40). As the male fastener (10) continues its rotational movement within the hole of the female fastener (42), the first completely-formed thread of the female fastener (41) that the boundary line contacts is the first completely-formed thread of the female fastener (41) on the side where the catching section (16) contacts the female fastener. When the male fastener (10) is rotated (R) manually or by an automation system, the incompleted threads (14b) in the coupling section (13b) cam over the female fastener threads (44) without cross threading and the threads in the body section (13a) of the shaft (14a) clamp to the threads (44) of the female fastener, advancing on the female fastener (40), thereby a proper connection is ensured (FIGS. 5D-5E).

[0064] In the fastener (10) according to the present invention, the surface of the coupling section (13b) of the shaft and the surface of the second portion of the catching section (16b) are curved. In more detail, the curved surface of the coupling section (13b) denotes an arc of the circle whose center (O.sub.1) is located outside the boundaries of the shaft (13) and is on the plane extending perpendicular to the longitudinal axis (X.sub.1) of the fastener at the level (17) where the shaft body section ends. The curved surface of the second portion of the catching section (16b) is also an arc of the circle whose center (O.sub.2) is located within the boundaries of the catching section (16) and on the plane extending perpendicular to the longitudinal axis (X.sub.1) of the fastener at the level (19) where the first portion of the catching section ends. The centers (O.sub.1, O.sub.2) of the said circles are represented in FIG. 7. The radius (R.sub.1) of the circle to which the arc indicating the curved surface of the coupling section (13b) belongs is larger than the radius (R.sub.2) of the circle to which the arc indicating the curved surface of the second portion of the catching section (16b) belongs.

[0065] Therefore, the present invention may be best adapted to achieve the above-mentioned objects and the intended results and advantages. Although a preferred embodiment of the present invention has been explained in detail above with figures and reference numbers to render the invention clearer, it should be noted that modifications and adaptations made to the technical elements of the invention within the scope of the invention are also included in order to achieve the same or similar objects within the scope of the invention.

DESCRIPTION OF THE REFERENCE NUMBERS IN THE FIGURES

[0066] 10: fastener [0067] 11: fastener head [0068] 12: bearing surface of fastener head [0069] 13: fastener shaft [0070] 13a: body section of fastener shaft [0071] 13b: coupling section of fastener shaft [0072] 14: threaded portion of fastener [0073] 14a: each of the threads in the threaded portion extending continuously helically in the body section of the shaft [0074] 14b: each of the incompleted threads in the threaded portion extending continuously helically in the coupling section of the shaft [0075] 15: the point where the continuous helical threaded portion of the shaft ends [0076] 16: catching section of fastener [0077] 16a: first portion of the catching section [0078] 16b: second portion of the catching section [0079] 17: the level where the body section of the shaft ends [0080] 18: boundary line between the coupling section of the shaft and the catching section [0081] 19: end of the first portion of the catching section [0082] 20: end of the catching section [0083] 40: female fastener [0084] 40a: the end of the female fastener in which the male fastener is inserted [0085] 40b: other end of the female fastener [0086] 41: first completely-formed thread of female fastener [0087] 41a: center of the first completely-formed thread of female fastener [0088] 42: hole of the female fastener [0089] 43: threaded portion of the female fastener [0090] 44: each of the threads in the threaded portion of the female fastener [0091] 50: fastener system [0092] X.sub.1: longitudinal axis of the male fastener [0093] X.sub.2: longitudinal axis of the female fastener [0094] d.sub.x: the length of the coupling section of the shaft [0095] d.sub.y: the length of the catching section [0096] d.sub.z: length of the second portion of the catching section [0097] d.sub.1: the diameter of the body section of the shaft [0098] d.sub.2: diameter of the first portion of the catching section [0099] d.sub.1: minor diameter of the thread of the body section of the shaft [0100] d.sub.1: major diameter of the thread of the body section of the shaft [0101] d.sub.2: minor diameter of thread of the coupling section [0102] d.sub.2: major diameter of thread of the coupling section [0103] h.sub.1: height of thread of the body section of the shaft [0104] h.sub.2: height of thread of the coupling section of the shaft [0105] O.sub.1: the center of the circle including the arc formed by the curved surface of the coupling section of the shaft [0106] O.sub.2: the center of the circle including the arc formed by the curved surface of the second portion of the catching section [0107] R.sub.1: the radius of the circle including the arc indicating the curved surface of the coupling section of the shaft [0108] R.sub.2: the radius of the circle including the arc indicating the curved surface of the second portion of the receiving section