Patent Application
20170146051
1. Field of the Invention
The present invention relates to an anti-loosen screw manufacturing method and a screw member produced thereby. Particularly, the present invention relates to the anti-loosen screw manufacturing method for forming a laterally-extruded thread portion.
2. Description of the Related Art
U.S. Pat. No. 6,454,506, entitled “ANCHOR BOLT WITH AN OUTER THREAD HAVING THREAD TURNS WITH DIFFERENT CROSS-SECTIONAL SHAPE,” discloses an anchor bolt having a substantially cylindrical stem and at least one thread provided on the stem. The thread extends from a free front end of the stem at least over a portion of a longitudinal extent of the stem.
The thread has a plurality of thread turns at least over one/third of the stem. A width decreases with an increase of a distance of a respective thread turn from the free front end of the stem, so that a distance between trailing and leading flanks of two following one another thread turns of the thread increases backwards.
A decrease of the width of the thread or an increase of the distance between the trailing flank and the leading flank can be suitable for intensifying an anchorage of the anchor bolt on constructions. However, the thread structure of the anchor bolt is unsuitable for effectively preventing the screw from loosening or falling off from a screw hole.
Further, Taiwanese Patent Publication No. TW-475670, entitled “IMPROVED STRUCTURE OF THREADS OF SCREWS,” discloses a screw having an anti-loosen structure. The screw includes a head, a shank and a plurality of slanted threads which extend along the shank. A predetermined section of the slanted threads is formed with a set of wavelike threads spaced apart from the head a predetermined distance.
The wavelike threads extend along the slanted threads and tilt to the adjacent slanted threads. In screwing operation, the wavelike threads are tightly engaged with corresponding threads of a screw hole. To a certain extent, the screw can be firmly locked in the screw hole to avoid unexpected loosening or falling off from the screw hole.
In fact, although the wavelike threads tilted to the adjacent slanted threads can provide a function of anti-loosen, it has deficiencies of complicated structures in the wavelike threads. Namely, the wavelike thread must be a single wavelike thread to regularly tilt to the adjacent slanted threads in a thread-rolling process. However, the additional wavelike threads further formed on the slanted threads result in difficulties in the thread-rolling process of the screws.
However, there is a need of improving the thread structure and the manufacturing method for providing an anti-loosen function of the screw after being screwed. The above-mentioned patent application publications are incorporated herein by reference for purposes including, but not limited to, indicating the background of the present invention and illustrating the situation of the art.
As is described in greater detail below, the present invention provides an anti-loosen screw manufacturing method and a screw member produced thereby. In thread-rolling process, a thread portion and a laterally-extruded thread portion are formed on a shank such that a groove of the thread portion is extruded to form one or a pair of laterally-extruded portions (e.g., two opposite extruded portions) and each of which are protruded in two adjacent grooves. In screwing operation, the two laterally-extruded portions are capable of engaging with inner threads of a screw hole for providing an anti-loosen function after being screwed in such a way as to eliminate the above problems of the conventional screw member.
The primary objective of this invention is to provide an anti-loosen screw manufacturing method and a screw member produced thereby. In thread-rolling process, a thread portion and a laterally-extruded thread portion are formed on a shank such that a groove of the thread portion is extruded to form one or a pair of laterally-extruded portions and each of which are protruded in two adjacent grooves. In screwing operation, the two laterally-extruded portions are capable of engaging with inner threads of a screw hole for providing an anti-loosen function. Advantageously, the screw member of the present invention is successful in providing an anti-loosen function after being screwed.
The anti-loosen screw manufacturing method in accordance with an aspect of the present invention includes:
combining a main die plate with a protruded die plate to form a combined die plate;
utilizing the main die plate of the combined die plate to execute a thread-rolling process on an outer circumferential surface of a shank portion to form an outer thread portion which includes a plurality of grooves; and
utilizing the protruded die plate of the combined die plate to execute an extrusion-forming process to form at least one or a plurality of laterally-extruded thread portions on one of the grooves of the outer thread portion in the thread-rolling process;
wherein each of the laterally-extruded thread portions is formed by laterally extruding at least one inclined wall of the groove of the outer thread portion with respect to a longitudinal direction thereof such that at least one laterally-extruded portion is protruded in an adjacent groove of the laterally-extruded groove for engaging with an inner thread of a screw hole; and
wherein the laterally-extruded thread portion widens a width of the groove such that the laterally-extruded portion is tightly engaged with an inclined surface of a groove of the inner thread of the screw hole.
The anti-loosen screw manufacturing method in accordance with another aspect of the present invention includes:
combining a main die plate with a protruded die plate to form a combined die plate;
utilizing the main die plate of the combined die plate to execute a thread-rolling process on an outer circumferential surface of a shank portion to form an outer thread portion which includes a plurality of grooves; and
utilizing the protruded die plate of the combined die plate to execute an extrusion-forming process to form at least one or a plurality of laterally-extruded thread portions on one of the grooves of the outer thread portion in the thread-rolling process;
wherein each of the laterally-extruded thread portions is formed by laterally extruding two inclined walls of the groove of the outer thread portion with respect to a longitudinal direction thereof such that two opposite laterally-extruded portions are protruded in a first adjacent groove and a second adjacent groove of the laterally-extruded groove for engaging with inner threads of a screw hole; and
wherein the laterally-extruded thread portion widens a width of the groove such that the two opposite laterally-extruded portions are tightly engaged with two inclined surfaces of two adjacent grooves of the inner threads of the screw hole.
The anti-loosen screw in accordance with an aspect of the present invention includes:
a shank portion provided with an outer circumferential surface;
an outer thread portion formed on the outer circumferential surface of the shank portion in a thread-rolling process, with the outer thread portion including a plurality of grooves; and
at least one or a plurality of laterally-extruded thread portions formed on one of the grooves of the outer thread portion in the thread-rolling process;
wherein each of the laterally-extruded thread portions is formed by laterally extruding at least one inclined wall of the groove of the outer thread portion with respect to a longitudinal direction thereof such that a first laterally-extruded portion is protruded in a first adjacent groove of the laterally-extruded groove for engaging with an inner thread of a screw hole; and
wherein the laterally-extruded thread portion widens a width of the groove such that the first laterally-extruded portion is tightly engaged with an inclined surface of a groove of the inner thread of the screw hole.
In a separate aspect of the present invention, two of the plurality of laterally-extruded thread portions has an included angle with respect to a longitudinal axis of the shank portion.
In a further separate aspect of the present invention, the included angle is 180°, 120°, 90°, 72° or 60°.
In yet a further separate aspect of the present invention, the plurality of laterally-extruded thread portions are equal-spaced apart to form a plurality of equal-spaced engaging points for engaging with the inner thread of the screw hole.
In yet a further separate aspect of the present invention, the outer thread portion has at least one thermal treatment layer to intensify strength of the laterally-extruded thread portion.
In yet a further separate aspect of the present invention, the laterally-extruded thread portion has a recession formed in a bottom surface of the groove and extended along the longitudinal direction thereof.
Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various will become apparent to those skilled in the art from this detailed description.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:
It is noted that an anti-loosen structure in accordance with the preferred embodiment of the present invention can be applicable to various screw nuts (e.g., hex flange nuts, hex slotted nuts, square nuts or wing nuts having inner threads for engaging with outer threads of screws or the like), bolts or screws, including for example, including machine screws, self-tapping screws, hexagon and hexagon socket screws, shoulder screws, Sems screws or other special screws, which are not limitative of the present invention. The anti-loosen screw manufacturing method and the screw member in accordance with the preferred embodiment of the present invention are applicable to various international standards, including ISO (International Organization for Standardization), ANSI (American National Standards Institute), JIS (Japanese Industrial Standards), DIN (German National Standards) and BSW (British Standard Whitworth) etc.
Further, the anti-loosen screw or screw nuts in accordance with the preferred embodiment of the present invention is made of various complex materials, metals or metal alloys, including magnesium, magnesium alloy, aluminum, aluminum alloy, stainless steel, low-carbon steel (mild steel), medium carbon steel, alloy steel, bronze, other metal (e.g., nonferrous metals) and metal alloy, for example.
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By way of example, the type of the threads 21 formed on the outer circumferential surface of the shank portion 10 are a single thread, a double thread, a high-low thread, a tri-lobular thread or other thread shape, which are not limitative of the present invention.
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Although the invention has been described in detail with reference to its presently preferred embodiment, it will be understood by one of ordinary skills in the art that various modifications can be made without departing from the spirit and the scope of the invention, as set forth in the appended claims.
