GB2476838A

GB2476838A - Screw

Info

Publication number: GB2476838A
Application number: GB1001268A
Authority: GB
Inventors: Li-Yun Chen
Original assignee: HWALLY PRODUCTS CO Ltd
Current assignee: HWALLY PRODUCTS CO Ltd
Priority date: 2010-01-12
Filing date: 2010-01-27
Publication date: 2011-07-13
Anticipated expiration: 2030-01-27
Also published as: GB2476838B; AU2010100782A4; GB201001268D0; TWM385613U; DE202010002158U1

Abstract

A screw 10 includes a head 14 and a shank 12. A first thread 18 is formed on an outer periphery of the shank 12 and includes a plurality of screw flights 20. The first thread 18 further includes a plurality of recessed portions 22. Each recessed portion 22 extends through an angle in a range of 45° -180° in a circumferential direction perpendicular to a longitudinal axis. Each recessed portion 22 includes a first end and a second end having a spacing to the insertion end larger than the first end. The first end of each recessed portion 22 has an end face at an angle in a range of 75° -110° to the outer periphery of the shank 12. A second thread 28 is formed on the outer periphery of the shank and includes a plurality of screw flights 30 each having a thread height smaller than the first thread 18.

Description

SCREW

BACKGROUND OF THE INVENTION

The present invention relates to a screw and, more particularly, a screw suitable for use in a cement ground or the like.

There are various types of screws for fixing objects to different materials such as wood, plastic, metal or cement. Screws for cements (or cement screws) generally include a helical thread including a plurality of screw flights to allow the screw to be screwing into a cement ground for fixing an object to the cement ground. However, the speed of screwing the screw into the cement ground depends on the number of the screw flights, because more screw flights cause higher friction with the cement. Furthennore, conventional cement screws are liable to be loosened due to vibrations or other reasons, resulting in undesired loosening of the object fixed to the cement ground.

Thus, a need exists for a cement screw allowing easy screwing into the cement ground while preventing undesired loosening.

SUMMARY OF THE INVENTION

The present invention solves this need and other problems in the field of reliable fixing of objects in a cement ground by providing, in a preferred form, a screw including a head and a shank having an engaging end interconnected to the head and an insertion end spaced from the engaging end along a longitudinal axis. A first thread is formed on an outer periphery of the shank and extends from the engaging end through the insertion end. The first thread includes a plurality of first screw flights each having a first thread height. The first thread further includes a plurality of recessed portions. Each of the plurality of recessed portions extends through an angle in a range of 45° -180° in a circumferential direction perpendicular to the longitudinal axis. Each of the plurality of recessed portions includes a first end and a second end having a spacing to the insertion end larger than the first end. The first end of each of the plurality of recessed portions has an end face at an angle in a range of 75°-1100 to the outer periphery of the shank. A second thread is formed on the outer periphery of the shank and extends from the engaging end through the insertion end and spaced from the first thread. The second thread includes a plurality of second screw flights each having a second thread height smaller than the first thread height.

In the most preferred form, each of the plurality of first screw flights is at an angle in a range of 80°-105 0 to the longitudinal axis. Each of the plurality of recessed portions is formed by removing a portion of one of the plurality of first screw flights, such that the recessed portion is free of the first thread height about 1/8 to 1/2 of a circumference of the first screw flight. The second end of each of the plurality of recessed portions has a diverging end face with respect to the outer periphery of the shank. Two of the plurality of recessed portions adjacent to each other are spaced by two pitches of the first thread along the longitudinal axis, and the plurality of recessed portions is aligned with each other along the longitudinal axis. Furthermore, a third thread is formed on the outer periphery of the shank and extends from the engaging end through the insertion end and spaced from the first and second threads. The third thread includes a plurality of third screw flights each having a third thread height smaller than the second thread height. The second thread is intermediate the first and third threads, and crests of first, second, and third thread heights in a cross section perpendicular to the longitudinal axis substantially represent a truncated cone tapering towards the insertion end. The first, second, and third threads have the same pitch.

The present invention will become clearer in light of the following detailed description of illustrative embodiments of this invention described in connection with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG 1 shows a perspective view of a screw according to the preferred teachings of the present invention.

FIG 2 shows a side elevation of the screw of FIG 1.

FIG 3 shows another side elevation of the screw of FIG I. FIG 4 shows a cross sectional view of the screw of FIG. 1 according to section line 4-4 of FIG 3.

FIG. 5 shows a cross sectional view of the screw of FIG. 1 according to section line 5-5 of FIG 2.

FIG 6 shows a cross sectional view of the screw of FIG 1 according to section line 6-6 of FIG 2.

FIG 7 shows an enlarged view of a lower circled portion of FIG 4.

FIG 8 shows an enlarged view of an upper circled portion of FIG 4.

All figures are drawn for ease of explanation of the basic teachings of the present invention only; the extensions of the figures with respect to number, position, relationship, and dimensions of the parts to form the preferred embodiments will be explained or will be within the skill of the art after the following teachings of the present invention have been read and understood. Further, the exact dimensions and dimensional proportions to conform to specific force, weight, strength, and similar requirements will likewise be within the skill of the art after the following teachings of the present invention have been read and understood.

Where used in the various figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the terms "first", "second", "third", "outer", "end", "portion", "spacing", "longitudinal", "circumferential", "height", and similar terms are used herein, it should be understood that these terms have reference only to the structure shown in the drawings as it would appear to a person viewing the drawings and are utilized only to facilitate describing the invention.

DETAILED DESCRIPTION OF THE INVENTION

A screw according to the preferred teachings of the present invention is shown in the drawings and generally designated 10. According to the preferred form shown, screw 10 includes a head 14 and a shank 12 extending from a side of head 14. Shank 12 includes an engaging end 15 interconnected to the side of head 14 and an insertion end 16 spaced from engaging end 15 along a longitudinal axis of shank 12. In the most preferred form shown, insertion end 16 has a flat end face. However, insertion end 12 can have a pointed end.

According to the preferred form shown, shank 12 includes a first thread 18 formed on an outer periphery of shank 12 and extending helically from engaging end 15 through insertion end 16. First thread 18 includes a plurality of screw flights 20 and has a pitch W. Each screw flight 20 has a first thread height Hi (FIG 7). Furthermore, an angle B (FIG. 8) between a flank of each screw flight 20 and the longitudinal axis is in a range of 80 -105. First thread 18 further includes a plurality of recessed portions 22 each of which is formed by removing a portion of one of screw flights 20. In the most preferred form shown, each recessed portion 22 extends through an angle S (FIG. 5) in a range of 45 -180° in a circumferential direction perpendicular to the longitudinal axis such that recessed portion 22 is free of first thread height Hi about 1/8 to 1/2 of a circumference of screw flight 20 having recessed portion 22. Each recessed portion 22 includes a first end 24 and a second end 26 having a spacing to insertion end 16 larger than first end 24. First end 24 of each recessed portion 22 has an end face at an angle A (FIG. 6) in a range of 75-110° to the outer periphery of shank 12. Second end 26 of each recessed portion 22 has a diverging end face with respect to the outer periphery of shank 12 (FIG. 5). Two adjacent recessed portions 22 are spaced by at least one pitch W along the longitudinal axis (FIG 3). In the most preferred form shown, two adjacent recessed portions 22 are spaced by two pitches (2W) along the longitudinal axis, and all of the recessed portions 22 are aligned along the longitudinal axis to allow easy manufacturing of screw 10. However, recessed portions 22 do not have to be aligned with each other along the longitudinal axis. Furthermore, two adjacent recessed portions 22 can be spaced by one or more than two pitches along the longitudinal axis.

According to the preferred form shown, the outer periphery of shank 12 further includes a second thread 28 extending helically from engaging end 15 through insertion end 16 and spaced from first thread 18. Second thread 28 includes a plurality of screw flights 30. In the most preferred form shown, second thread 28 has a pitch the same as that of first thread 18. Furthermore, each screw flight 30 of second thread 28 has a second thread height H2 (FIG 7) smaller than first thread height Hi.

According to the preferred form shown, the outer periphery of shank 12 further includes a third thread 28 extending helically from engaging end 15 through insertion end 16. Third thread 32 includes a plurality of screw flights 34 spaced from first and second threads 18 and 28. In the most preferred form shown, third thread 32 has a pitch the same as that of first thread 18. Furthermore, each screw flight 34 of third thread 32 has a third thread height H3 (FIG 7) smaller than thread height H2. Second thread 28 is intermediate first and third threads 18 and 32, such that the crests of first, second, and third thread heights Hi, H2, and H3 in a cross section perpendicular to the longitudinal axis substantially represent a truncated cone tapering towards insertion end 16 (see phantom line 36 in FIG 7).

Screw 10 according to the preferred teachings of the present invention can be utilized to fix an object to a cement ground or the like. It can be appreciated that by providing recessed portions 22 in first thread 18, loosening of screw 10 according to the preferred teachings of the present invention can be effectively avoided. Specifically, after screwing screw 10 into a cement ground or the like, rotating screw 10 in a loosening direction will encounter considerable resistance. This is due to provision of angle A (of each recessed portion 22 between the end face of first end 24 of recessed portion 22 and the outer periphery of shank 12) is in a range of 750 -110°, due to provision of angle B (between the flank of each screw flight 20 and the longitudinal axis) in a range of 80°-l05°, and due to provision of recessed portions 22 each extending through an angle S in a range of 450180 0* Loosening of screw 10 is, thus, avoided.

Furthermore, first, second, and third threads 18, 28, and 30 having different thread heights Hi, 112, and H3 allows screw 10 according to the preferred teachings of the present invention to be easily and smoothly screwed into the cement ground with less effort and without adversely affect by recessed portions 22. Specifically, second and third threads 28 and 32 having smaller thread heights H2 and H3 are formed between two adjacent screw flights 20 of first thread 18 having a larger thread height Hi to serve as a buffering section while screwing screw i 0 into the cement ground. Further, after i 5 engagement of first thread 18 with the object to be fixed to the cement ground, second and third threads 28 and 32 also engage with the object at other portions of the object, increasing the engaging area between screw 10 and the cement ground and, thus, enhancing fixing of the object. Furthermore, the relationship of first, second, and third thread heights Hi, H2, and 113 of first, second, and third threads 18, 28, and 32 enhances easy screwing of screw 10 into the cement ground and prevention of loosening of screw 10.

Thus since the invention disclosed herein may be embodied in other specific forms without departing from the spirit or general characteristics thereof, some of which forms have been indicated, the embodiments described herein are to be considered in all respects illustrative and not restrictive. The scope of the invention is to be indicated by the appended claims, rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Claims

Claims: 1. A screw comprising: a head; a shank including an engaging end and an insertion end spaced from the engaging end along a longitudinal axis, with the engaging end of the shank interconnected to the head; a first thread formed on an outer periphery of the shank and extending from the engaging end through the insertion end, with the first thread including a plurality of first screw flights each having a first thread height, with the first thread further including a plurality of recessed portions, with each of the plurality of recessed portions extending through an angle in a range of 450 1800 in a circumferential direction perpendicular to the longitudinal axis, with each of the plurality of recessed portions including a first end and a second end having a spacing to the insertion end larger than the first end, with the first end of each of the plurality of recessed portions having an end face at an angle in a range of 7501100 to the outer periphery of the shank; and a second thread formed on the outer periphery of the shank and extending from the engaging end through the insertion end and spaced from the first thread, with the second thread including a plurality of second screw flights each having a second thread height smaller than the first thread height.
2. The screw as claimed in claim 1, with each of the plurality of first screw flights being at an angle in a range of 8001050 to the longitudinal axis.
3. The screw as claimed in claim 2, with each of the plurality of recessed portions being formed by removing a portion of one of the plurality of first screw flights, such that the recessed portion is free of the first thread height about 1/8 to 1/2 of a circumference of the first screw flight.
4. The screw as claimed in claim 3, with the second end of each of the plurality of recessed portions having a diverging end face with respect to the outer periphery of the shank.
5. The screw as claimed in claim 3, with two of the plurality of recessed portions adjacent to each other being spaced by at least one pitch of the first thread along the longitudinal axis, and with the plurality of recessed portions aligned with each other along the longitudinal axis.
6. The screw as claimed in claim 3, further comprising: a third thread formed on the outer periphery of the shank and extending from the engaging end through the insertion end and spaced from the first and second threads, with the third thread including a plurality of third screw flights each having a third thread height smaller than the second thread height.
7. The screw as claimed in claim 6, with the second thread intermediate the first and third threads, and with crests of first, second, and third thread heights in a cross section perpendicular to the longitudinal axis substantially representing a truncated cone tapering towards the insertion end.
8. The screw as claimed in claim 7, with the first, second, and third threads having the same pitch.
9. The screw as claimed in claim 8, with two of the plurality of recessed portions adjacent to each other being spaced by two pitches along the longitudinal axis, with the plurality of recessed portions aligned with each other along the longitudinal axis, and with the second end of each of the plurality of recessed portions having a diverging end face with respect to the outer periphery of the shank.
10. The screw substantially as hereinbefore described with reference to and as shown in the accompanying drawings.