AU2004200317A1 - Screw including wings with serrated edges - Google Patents

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Screw including wings with serrated edges The following statement is a full description of this invention, including the best method of performing it known to us: SCREW INCLUDING WINGS WITH SERRATED EDGES The invention relates to a screw, more particularly to a screw for a plastic panel.

Referring to Figure 1, a conventional iron shed is made by covering a top frame of the shed (not shown) with a corrugated iron panel 1 and by securing the iron panel 1 thereto through a first conventional screw 2.

A rubber pad 22 is disposed between a head 21 of the screw 2 and the iron panel 1. When the screw 2 is driven into the iron panel 1, the rubber pad 22 is pressed by the head 21 of the screw 2 and the iron panel 1 so as to achieve a waterproof effect.

Presently, consumers prefer plastic panels over the iron panels because of the characteristics of higher light transmissivity and better appealing appearance of the former. Becauseplasticpanels expand when heated and contract when cooled, a shank portion of the screw 2 must not be in contact with the plastic panel when it is driven into the plastic panel. Otherwise, cracks can be formed when the plastic panel expands and presses against the screw 2 due to high temperature. The cracks are enlarged when the plastic panel contracts due to subsequent cooling of the same.

To solve the aforementioned drawback, a second conventional screw 3, as shown in Figure 2, has been proposed. The screw 3 comprises a shank portion 31, a head portion 32 connected to one end of the shank portion 31, a screw thread portion 33 that spirals downwardly along the shank portion 31, two diametrically opposite wings 34 connected to the shank portion 31 and disposed above the screw thread portion 33, and a rubber pad sleeved on an outer periphery of the shank portion 31.

Referring to Figure 3, a through hole 41 is formed in a plastic panel 4 when the screw thread portion 33 of the screw 3 is driven continuously into the plastic panel 4 until the wings 34 squeeze through the plastic panel 4. As the wings 34 bore through the plastic panel 4, the plastic panel 4 exerts a similar counteracting force to the wings 34 so that a peripheral wall defining the through hole 41 is damaged. As a result, the rubber pad 35 cannot contact flatly the plastic panel 4, and the desired waterproofing effect cannot be achieved.

A third conventional screw 5 has been proposed to overcome the aforesaid drawbacks. Referring to Figure 4, the screw 5 is shown to be substantially similar to the screw 3 shown in Figure 2, the improvement residing in the configuration of the wings. The wings 54 of the screw 5 are formed as inverted hooks with sharp pointed ends. Through the sharp pointed ends of the wings 54, a through hole that is larger than a major diameter of the shank portion 51 of the screw 5 can be formed in a plastic panel (not shown). However, one of the drawbacks of the screw 5 is that the wings 54 are too sharp, and can cause injuries during use of the screw Furthermore, the rubberpad 55 is likelytobepierced by the sharp pointed ends of the wings 54 when it is sleeved on the shank portion 51 of the screw Therefore, the object of the present invention is to provide a screw that can easily bore a hole in a panel and that is safe to use.

According to this invention, a screw comprises a head portion, a shank portion, and a wing unit. The shank portion extends axially from the head portion, and has a threaded section distal from the head portion, and a non-threaded section between the head portion and the threaded section. The wing unit projects from an outer surface of the non-threaded section, and includes at least one wing member having a first end adjacent to the threaded section, and a second end opposite to the first end. The wing member is tapered from the second end to the first end so as to form an inclined edge extending from the second end to the'first end. The edge is serrated to form a plurality of teeth which project axially from the edge toward the threaded section.

Other features and advantages of the present inventionwillbecomeapparent inthefollowingdetailed descriptionofthepreferredembodimentswithreference to the accompanying drawings, of which: Figure 1 is a schematic view of a first conventional screw in a state of use; Figure 2 is a schematic view of a second conventional screw; Figure 3 is a partly sectional view, illustrating a damage to a peripheral wall defining a through hole in a plastic panel when the second conventional screw is driven through the plastic panel; Figure 4 is a schematic view of a third conventional screw; Figure 5 is a schematic view of the first preferred embodimentof a screwaccordingtothepresent invention; Figure 6 is a fragmentary partly sectional view, illustrating the screw of the present invention in a state of use; and Figure 7 is a schematic view of the second preferred embodiment of a screw according to the present invention.

Before the present invention is described in greater detail, it should be noted that like elements are denoted by the same reference numerals throughout the disclosure.

Referring to Figures 5 and 6, the first preferred embodiment of a screw 6 according to the present invention is shown to comprise a head portion 62, an axially extending shank portion 61, and a wing unit The shank portion 61 is connected to the head portion 62, and extends along a Z-axis. The shank portion 61 has a threaded sedtion 612 distal from the head portion 62, and a non-threaded section 611 between the head portion 62 and the threaded section 612. The threaded section 612 has a first end part 6121 that is formed with a flute 66 and that has a sharp pointed end 614 opposite to the head portion 62, a second end part 6122 connected to the first end part 6121 and disposed adjacent to the non-threaded section 611, and a major diameter (X) The wing unit 65 projects from an outer surface of the non-threaded section 611 of the shank portion 61, and includes apluralityof wingmembers 650 that project outwardly and radially from the outer surface of the non-threaded section 611 and that are spaced apart angularly from each other relative to the Z-axis. In this embodiment, the wing unit 65 includes two diametrically opposite wing members 650. However, the exactnumber ofthewing members 650shouldnot belimited to the disclosed embodiment since the presence of one or more wing members 650 can achieve same purpose. Each of the wing members 650 has a first end 653 adjacent to the second end part 6122 of the threaded section 612, and a second end 654 opposite to the first end 653. Each wing member 650 is substantially triangular in shape, and is tapered from the second end 654 to the first end 653 so as to form an inclined and serrated edge 651 extending from the second end 654 to the first end 653.

The edge 651 includes a plurality of teeth 652 which project axially from the edge 651 toward the threaded section 612 of the shank portion 61. Each wing member 650 has a greatest radial dimension larger than one-half the major diameter of the threaded section 612 of the shank portion 61.

A washer 64 is sleeved detachably on an outer periphery of the non-threaded section 611 of the shank portion 61, and is disposed between the head portion 62 and the wing unit With further reference to Figure 6, the screw 6 of the present invention is applied to fasten a plastic panel 7 on a top frame of a shed (not shown) The washer 64 is first sleeved on the shank portion 61, after which a torque is applied to the head portion 62 so that the pointed end 614 of the threaded section 612 pierces through the plastic panel 7 and guides the first end part 6121 of the threaded section 612 gradually into the plastic panel 7 so as to form a bore 71 in the plastic panel 7. At the same time, the flute 66 acts to discharge shavings from the plastic panel 7. During the continuous drivingof the screw 6 into the top frame, the wingmembers 650 pass through the bore 71 simultaneously. Because the greatest radial dimension (see Figure 5) of each wing member 650 is larger than one-half the major diameter (see Figure 5) of the threaded section 612 of the shank portion 61, the initial dimension of the bore 71 produced is not enough to permit smooth passage of the wing members 650 therethrough. However, since each wing member 650 has the inclined and serrated edge 651, the wing members 650 can gradually cut through a peripheral wall defining thebore 71 intheplasticpanel 7 so as to enlarge the diameter of the bore 71, thereby permitting the wing members 650 to pass therethrough.

Finally, the washer 64 is pressed by the head portion 62 of the screw 6 and the plastic panel 7 since it has a cross-sectional area larger than that of the bore 71, and closes tightly the bore 71 to achieve a waterproof effect.

The main feature of the present invention resides in the inclined and serrated edge 651 of each wing member 650 which cuts through the plastic panel 7 instead of squeezing through the same as performed by the wings 34 of the aforementioned conventional screw 3. The serrated edges 651 of the wing members 650 gradually cut through the plastic panel 7 during the drilling operation of the screw 6, thereby enlarging the bore 71. Since the resultant bore 71 is larger than the major diameter of the shank portion 61, the shank portion 61 is not in direct contact with the plastic panel 7, thereby avoiding cracking of the plastic panel 7 during its expansiondue to heat and contractiondueto coldness.

Furthermore, since the resultant bore 71 has a regular shape, and since the peripheral wall defining the bore 71 is not deformed, the washer 64 can contact flatly the plastic panel 7, thereby sealing the bore 71 to achieve the desired waterproof effect.

Although the inclined and serrated edges 651 of the wing members 650 can cut through the plastic panel 7, the serrated edges 651 are fine and are not sharp enough to pierce through the washer 64 when the washer 64 is sleeved on the shank portion 61.

Referring to Figure 7, the second preferred embodiment of a screw 6 according to the present invention is shown to be substantially similar to the first preferred embodiment. However, in thisembodiment, the threaded section 612 of the shank portion 61 has a blunt drilling end 614' opposite to the head portion 62. The wing unit 65 includes three wing members 650 (only two are visible) that are angularly spaced apart on the non-threaded section 611 of the shank portion 61. The screw 6 in this embodiment is a self-tapping screw.

It should be noted that in the second preferred embodiment, the three wing members 650 are angularly and equally spaced apart from each other and are distributed evenly about the non-threaded section 611 of the shank portion 61. As such, during boring of the plastic panel 7, the screw 6 can shave evenly the plastic panel 7 to further enhance the working quality.

Claims (6)

1. 2. The screw as claimed in Claim 1, wherein said wing unit includes a plurality of said wing members which are spaced apart angularly.
2. 3. The screw as claimed in Claim 1, wherein said wing member has a greatest radial dimension larger than one-half the major diameter of said threaded section.
3. 4. The screw as claimed in Claim i, wherein said threaded section has a sharp pointed end opposite to said head portion. The screw as claimed in Claim i, wherein said threaded section has a blunt drilling end opposite to said head portion.
4. 6. The screw as claimed in Claim 1, further comprising a washer sleeved detachably on said shank portion, and disposed between said head portion and said wing unit.
5. 7. The screw as claimed in Claim i, wherein said wing member is substantially triangular in shape.
6. 8. The fastener substantiallyas hereinbefore described with reference to and as illustrated in Figures 5 to 7 of the accompanying drawings. FASTENER CO., LTD. By its Registered Patent Attorneys Freehills Carter Smith Beadle 28 January 2004