AU2021221841A1

AU2021221841A1 - Drill tip screw

Info

Publication number: AU2021221841A1
Application number: AU2021221841A
Authority: AU
Inventors: Matthew Augimeri
Original assignee: BREMICK Pty Ltd
Current assignee: BREMICK Pty Ltd
Priority date: 2021-08-25
Filing date: 2021-08-25
Publication date: 2023-03-16

Abstract

A drill tip screw is provided comprising: a head; a drill tip having at least two angled blades diverging from a point to define maximum tip width; and pa shank extending between the head and the drill tip. The shank includes at least one threaded portion and an unthreaded portion. The threaded portion includes a major thread starting at the drill tip and extending towards the head. The threaded portion has a root diameter, the major thread has a major thread diameter and the maximum tip width is at least 112% of the root diameter and less than 90% of the major thread diameter. 2/3 100 100 110 110 112 112 114 114 1,9122 19122 120 129 123 123 124 124 1125 12112 12134 134 10 5 16130 136 Figure 2 Figure 3

Description

2/3

100 100 110 110

112 112 114 114 1,9122 19122

120 129

123 123

124 124

1125

12112

12134 134

10 5 16130 136

Figure 2 Figure 3

DRILL TIP SCREW FIELD

[00011 The present disclosure is directed to a screw, and more particularly to a drill tip screw.

BACKGROUND

[00021 Screws having a drill tip to bore a pilot hole for the shank to follow into a substrate material are known. Examples of such drill tips are self-drilling drill tips and spear-point tips. These drill tips are generally provided with at least two angled blades diverging from a point to define a maximum tip width.

[0003] The utilisation of a drill tip compared to other tips may reduce the amount of time required to drive the screw into the substrate material. However, if the maximum tip width of the screw is greater than the root diameter of the shank, the drill tip reduces the amount of material the thread screws into, thereby reducing the pull out strength of the screw. Accordingly, there has not been widespread adoption of drill tip screws for applications where their reduced drive times may provide substantial benefits. In addition, when drill tip screws have been adopted, they usually exhibit maximum tip widths only slightly greater than the root diameter, potentially out of concern that greater maximum tip widths will have a too substantial detrimental impact on pull-out strength.

[0004] In light of these and other limitations and trade-offs involved in the use or non-use of drill tip screws, there is a need for alternative forms of drill tip screws for use by the fastener industry.

[00051 Reference to any prior art in the specification is not an acknowledgment or suggestion that this prior art forms part of the common general knowledge in any jurisdiction or that this prior art could reasonably be expected to be understood, regarded as relevant, and/or combined with other pieces of prior art by a skilled person in the art.

SUMMARY OF THE INVENTION

[0006] According to an aspect of the present invention, there is provided a screw comprising: a head; a drill tip having at least two angled blades diverging from a point to define maximum tip width; and a shank extending between the head and the drill tip, and including at least one threaded portion and an unthreaded portion, the threaded portion including a major thread starting at the drill tip and extending towards the head, wherein the threaded portion has a root diameter, the major thread has a major thread diameter and the maximum tip width is at least 112% of the root diameter and less than 90% of the major thread diameter.

[0007] In an embodiment, the maximum tip width is at least 118%, 122% or 126% of the root diameter, and/or the maximum tip width is less than 131% of the root diameter.

7 9 % or 82% of the

[0008] In an embodiment, the maximum tip width is at least 73%, 77%, major diameter, and/or the maximum tip width is less than 89% of the major diameter.

[0009] In an embodiment, the threaded portion includes a secondary or low thread starting at the drill tip and extending towards the head to define in combination with the major thread a high/low thread, the low thread having a low thread diameter less than the major thread diameter.

[0010] In an embodiment, the maximum tip width is at least 89%, 94%, 97% or 100% of the low thread diameter, and/or the maximum tip width is less than 108% of the low thread diameter.

[0011] In an embodiment, the two angled blades are diametrically opposed primary blades and the drill tip further comprises two diametrically opposed, secondary angled blades orientated perpendicular to the primary blades.

[0012] In an embodiment, the drill tip is a spear-point tip or a self-drilling drill tip

[0013] In an embodiment, the drill tip screw further comprises a second threaded portion including a top thread starting at the head and extending towards the drill tip.

[0014] In an embodiment, the major thread is formed with a plurality of swarf indents, the plurality of swarf indents forming at least one swarf channel.

[0015] In an embodiment, the at least one swarf channel is coextensive with the major thread.

[0016] In an embodiment, the swarf indents are equi-spaced from one another every 180, 120, or 900along the major thread depending on the number of swarf indents or swarf channels.

[0017] In an embodiment, each swarf indent is offset from an adjacent swarf indent.

[0018] In an embodiment, the head has a tool engaging formation.

[0019] In an embodiment, the tool engaging formation is one of a Torx recess, a hex recess, a square recess, a Phillips recess, a spanner recess, a tri-wing recess, a clutch recess, a one-way recess, a Phillips-slot combination, and a square-slot combination.

[0020] In an embodiment, the head is one of a bugle head, a dome or contour head, and a truss head.

[0021] In an embodiment, an underside of the head has a plurality of ribs.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] A preferred embodiment of the present invention is described, by way of example only, with reference to the accompanying figures, wherein:

[0023] Figure 1 is an isometric view of a screw according to an embodiment of the present invention;

[0024] Figure 2 is a side view of the screw of Figure 1;

[0025] Figure 3 is another side view of the screw of Figure 1;

[0026] Figure 4 is an enlarged partial view of the portion of the screw in the rectangle labelled "4" in Figure 1;

[0027] Figure 5 is an enlarged partial view of the portion of the screw in the circle labelled "5" in Figure 2;

DETAILED DESCRIPTION

[0028] Figures 1 to 3 show a screw 100 according to an embodiment of the present invention in the form of a bugle batten screw. The screw 100 has a head 110, a shank 120, and a drill tip in the form of a spear-point tip 130. The shank 120 extends between the head 110 and the spear point tip 130. It will be appreciated that, in other embodiments, alternative forms of drill tip may be utilised, such as a self-drilling drill tip.

[0029] The head 110 is a bugle head, which allows the screw 100 to be countersunk. The underside 112 of the head 110 has equi-spaced ribs 114, which assist in the countersinking process. The head 110 has four ribs 114, however, it will be appreciated that the head 110 may have more or less ribs 114. For example, screws with larger heads may have more ribs and screws with smaller heads may have fewer ribs. Although the head 110 of the screw 100 has been described and illustrated as a bugle head, it is envisaged that the head 110 may be a dome or contour head, a truss head, or any other suitable head known in the art. It will be appreciated that the type of head used for the screw 100 may vary depending on the intended use of the screw 100.

[0030] As best seen in Figure 1, the head 110 has a tool engaging recess 116 in the form of a hex recess. It will be appreciated that various other types of tool engaging or drive recesses or formations may be provided, including a Torx recess, a square recess, a Phillips recess, a spanner recess, a tri-wing recess, a clutch recess, one-way recess or combinations thereof such as a Phillips-slot combination or a square slot combination. External drives may also be provided such as a hexagonal or Torx drive.

[0031] The shank 120 has a first threaded portion 121, a second threaded portion 122, and a non-threaded portion 123 disposed between the first threaded portion 121 and second threaded portion 122. The first threaded portion 121 extends along the shank 120 from the spear-point tip 130 towards the head 110. The second threaded portion 122 extends along the shank 120 from the head 110 towards the spear-point tip 130.

[0032] Referring to Figures 2 and 3, the first threaded portion 121 includes a single start high or major thread 124 and a single start low or secondary thread 125. The high thread 124 and the low thread 125 both extend along the shank 120 from the spear-point tip 130 towards the head 110 and together define a high/low thread. It will be appreciated that, in other embodiments, the first threaded portion may include alternative thread arrangements, such as a single start high or major thread (with no low thread) or a twin start high or major thread.

[0033] The high thread 124 and the low thread 125 are both coextensive with the first threaded portion 121 such that the high/low thread is also coextensive with the first threaded portion 121. As the high thread 124 and the low thread 125 are coextensive with the first threaded portion 121, the number of turns of the high thread 124 is equal to the number of turns of the low thread 125. However, it is also envisaged that the low thread 125 may not be coextensive with the high thread 124 such that the number of turns of the low thread 125 is less than the number of turns of the high thread 124. Without wishing to be bound by theory, it is considered that the presence of at least one full turn of such a high/low thread at the spear-point tip 130 may result in improved drilling speeds in comparison to a similar screw using only a corresponding single start high thread.

[0034] Referring to Figure 5, the high thread 124 has a high thread diameter DHT, the low thread 125 has a low thread diameter DLT, and the shank 120 has a root/minor diameter DR. The high thread diameter DHT is greater than the low thread diameter DLT, which is greater than the root/minor diameter DR of the shank 120.

[0035] As best seen in Figures 2 and 3, the high thread 124 has a series of swarf indents 126 commencing from the beginning of the high thread 124 at the spear-point tip 130. The swarf indents 126 define a swarf channel 127 that promotes the removal of swarf as the screw 100 is being screwed into a material.

[0036] The swarf indents 126 are equi-spaced from one another roughly every 1800, 120° or ° along the high thread 124 depending on the number of swarf indents 126 or swarf channels 127. Each swarf indent 126 is slightly offset from an adjacent swarf indent 126. The swarf channel 127 only extends for the first seven turns of the high thread 124. However, it is envisaged that the swarf channel 127 may extend more or fewer turns of the high thread 124. For example, the swarf channel 127 may extend for all the turns of the high thread 124 such that the swarf channel 127 is coextensive with the first threaded portion 121 and the high thread 124. In another example, if the low thread 125 is not coextensive with the first threaded portion 121, the swarf channel 127 may only extend the length of the low thread 125.

[0037] As best seen in Figure 4, each swarf indent 126 has a substantially triangular profile when viewed in the axial direction of the screw 100. For each swarf indent 126, the point 128 of the swarf indent 126 has an included angle of approximately 105 degrees and the depth to which the point 128 is indented into the high thread 124 substantially corresponds to the difference between the high thread diameter DHT and the low thread diameter DLT. However, it will be appreciated that the points 128 of the swarf indents 126 may be formed with different included angles. For example, the included angle of the point 128 of each swarf indent 126 may be in the range of 90° to 120.

[0038] Although the swarf indents 126 have been described and illustrated as forming a swarf channel 127, it is envisaged that the screw 100 may have a plurality of swarf indents 126 that form more than one swarf channel 127. It is also envisaged that the low thread 125 may include a plurality of swarf indents. It will be further appreciated that swarf indents of different depths may be utilised. For example, in an embodiment where the low thread 125 also includes a plurality of swarf indents, it may be advantageous for the swarf indents 126 in the high thread

124 to have a depth that is greater than the difference between the high thread diameter DHTand the low thread diameter DLT.

[0039] Referring to Figures 1 to 3, the second threaded portion 122 has a top thread 129 for anchoring the screw 100 more firmly while being countersunk. The top thread 129 extends along the shank 120 from the head 110 towards the spear-point tip 130 and includes four full turns. However, the top thread 129 may have more or fewer turns. For example, the number of turns of the top thread 129 may vary depending on the length and gauge of the screw. The top thread 129 has a top thread diameter, which may be equal to, less than, or greater than the high thread diameter DHT. It is also envisaged that the screw 100 may omit the second threaded portion 122 such that the non-threaded portion 123 extends from the first threaded portion 121 to the head 110.

[0040] Referring to Figure 5, the spear-point tip 130 has two primary angled blades 132 and 134 that taper to a point 136. The primary blades 132 and 134 are diametrically opposed and define the primary or maximum tip widthWs1of the spear-point tip 130. Referring to Figures 3 and 5, the spear-point tip 130 also has two diametrically opposed secondary angled blades 133 and 135 that taper to the point 136. The secondary blades 133 and 135 are orientated perpendicular to the primary blades 132 and 134.The primary and secondary blades 132, 133, 134 and 135 are configured to drill through various types of materials to provide a pilot hole for the shank 120. For example, the primary and secondary blades 132, 133 134 and 135 may be configured to drill through various materials such as hardwoods, fibre cement sheets, masonry, particleboard, plywood and polymers.

[0041] As best seen in Figure 5, in this embodiment, the maximum tip widthWs1of the spear-point tip 130 is greater than the low thread diameter DLTbut less than the high thread diameter DHT. Accordingly: • the high thread diameter DHTis greater than the maximum tip widthWs1of the spear point tip 130 and the low thread diameter DLT; • the maximum tip widthWs1of the spear-point tip 130 of this embodiment is greater than the low thread diameter DLT; and • the root/minor diameter DRof the shank 120 is less than the low thread diameter DLT, the maximum tip widthWs1of the spear-point tip 130, and the high thread diameter DHT.

[0042] The inventors developed six test bugle batten screws substantially in accordance with the embodiment described above with respect to Figures 1-5, to compare drilling speed and pull out strength against standard bugle batten screws. Each test screw was in the form of a bugle batten screw having:

• a root/minor diameter DR with a lower tolerance DRL of 4.9 mm and an upper tolerance DRU of 5.0 mm,

* a low thread diameter DLT with a lower tolerance DLTL of 5.9 mm and an upper tolerance DLTU 6.3 mm,

* a high or major thread diameter DHT with a lower tolerance DHTL of 7.2 mm and an upper tolerance DHTU of 7.7 mm,

* a pitch of 5 mm (distance between adjacent major or high threads, or distance between adjacent low threads), and

• a height of the maximum tip width with a lower tolerance 4.52 mm and an upper tolerance 4.6 mm.

The maximum tip width Ws1 of the spear-point tip 130 of each test screw was varied to study its effect on the drill time and pull-out strength of the test screws. Each test screw was drilled into 2 x 90mm x 45mm pinewood sections and the drill time and pull-out strength for each test screw

was recorded (see Table 1 below). A standard bugle batten screw with a Type 17 sharp point and having the same root/minor diameter, low thread diameter and high thread diameter was also drilled into 2 x 90mm x 45mm pinewood sections. The mean drill time for this standard bugle batten screw was recorded as 8.18 seconds, and used as the base for the comparison in Table 1 below.

Table 1

Test WSTL WsTu Test screw drilling %of test screw drill time to Pull-out screw (mm) (mm) time (seconds) standard screw drill time strength (kN) 1 6.9 7.0 3.02 37% 2.9 2 5.6 5.8 6.75 83o 6.3 3 5.9 6.1 5.2 64% 6.0 4 6.1 6.2 4.52 55% 5.6 5 6.3 6.4 4.01 49°/ 5.76 6 6.4 6.5 3.87 47°/ 4.71

[0043] Generally, standard bugle batten screws on the market commonly have pull-out strength values of between 5.6 kN and 6.8 kN. In addition, Australian Standard AS 3566.1 requires a pull-out strength of at least 3.1 kN. From Table 1 above, it can be seen that, whilst all test screws 1 to 6 have lower drilling times than a standard bugle batten screw, only test screws 2 to 6 satisfy the pull-out strength requirement of Australian Standard AS 3566.1. In addition, only test screws 2 to 5 have pull-out strength values comparable to standard bugle batten screws commonly found on the market, with test screws 5 and 6 generally corresponding to the embodiment depicted in Figures 1 to 5, i.e. having a maximum tip widthWs1greater than the low thread diameter DLT.

[0044] The inventors posit that when a drill tip screw has a maximum tip widthWs1that is similar to, or only slightly larger than, the root diameter DR, it is the relationship between these two variables that dominates the amount of friction experienced by the screw when drilled into a substrate material, thereby influencing the drill time. However, once the maximum tip widthWs1 reaches a certain percentage of the root diameter DR, the inventors posit that the relationship between the maximum tip widthWs1and the major thread diameter DHTbecomes the dominant function in calculating the amount of friction experienced by the screw when drilled into a substrate material. Accordingly, at greater maximum tip widthWs1values, it is this relationship that plays the dominant role in influencing the drill time. If a high/low thread is used, the inventors have found that the relationship between the maximum tip widthWs1and the low thread diameter DLTalso has an effect. Accordingly, Table 2 below sets out the maximum tip widthWs1to root diameter DRratio, the maximum tip widthWsto major thread diameter DHT

ratio, the maximum tip widthWs1 to low thread diameter DLTratio, for the upper and lower tolerances of the test screws as outlined above.

Table 2

Tip width Tip width WsT to root Tip width WsT to major Tip width WsT to low Test WsT diameter DR ratio thread diameter DHT ratio thread diameter DLT ratio screw WSTL WsTu WSTu/DRL WSTL/DRU WSTU/DHTL WSTL /DHTu WsTu/DLTL WSTL/DLTU

(mm) (mm) (%) (%) (%) (%) (%) (%)

1 6.9 7.0 143% 138% 97% 90% 119% 110% 2 5.6 5.8 118% 112% 81% 73% 98% 89% 3 5.9 6.1 124% 118% 85% 77% 103% 94% 4 6.1 6.2 127% 122% 86% 79% 105% 97% 5 6.3 6.4 131% 126% 89% 82% 108% 100% 6 6.4 6.5 133% 128% 90% 83% 110% 102%

[0045] It can be seen from Table 2 above, when read in combination with Table 1 above, that drill times can be reduced, in comparison to a standard bugle batten screw with a Type 17 sharp point, when the maximum tip widthWs1is at least 112% of the root diameter DR. These drill times reduce further as the maximum tip widthWs1increases to at least 118%, at least 122% and at least 126% of the root diameter DR. However, it can be seen that the improvement in drill time gradually tapers off as the maximum tip widthWs1increases such that there do not appear to be significant gains from increasing the maximum tip widthWs1beyond 131% of the root diameter DR.

[0046] It also can be seen from Table 2 above, when read in combination with Table 1 above, that the pull-out strength values will satisfy Australian Standard AS 3566.1 as long as the maximum tip widthWs1is less than 90% of the major thread diameter DHT. The pull-out strength values gradually decrease as the maximum tip widthWs1increases from at least 73% of the major thread diameter DHT, to at least 77%, at least 79% and at least 82% of the major thread diameter DHT. 89% of the major thread diameter DHTappears to be the upper bound of the maximum tip widthWs1to ensure that the pull-out strength values are comparable to market values.

[0047] Finally, it can be seen from Table 2 above, when read in combination with Table 1 above, that the low thread can be configured such that the maximum tip widthWs1can be at least 8 9 %, at least 94%, at least 9 7 % and even at least 100% of the low thread diameter DLT, without having a significant detrimental impact on the pull-out strength of the screw. 108% of the low thread diameter DLTappears to be the upper bound of the maximum tip widthWs1 to allow that the low thread to assist in ensuring that the pull-out strength values are comparable to market values.

[0048] Accordingly, screws manufactured according to embodiments of the present invention may reduce the time it takes to drill the screw into a material compared to traditional screws, without any significant detrimental impacts on pull-out strength, thereby potentially reducing the labour time and, therefore, labour costs, especially if the job requires a significant amount of screws to be installed.

[0049] As used herein, except where the context requires otherwise, the term "comprise" and variations of the term, such as "comprising", "comprises" and "comprised", are not intended to exclude further additives, components, integers or steps.

[0050] It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

Claims

1. A drill tip screw comprising: a head; a drill tip having at least two angled blades diverging from a point to define maximum tip width; and a shank extending between the head and the drill tip, and including at least one threaded portion and an unthreaded portion, the threaded portion including a major thread starting at the drill tip and extending towards the head, wherein the threaded portion has a root diameter, the major thread has a major thread diameter and the maximum tip width is at least 112% of the root diameter and less than 90% of the major thread diameter.

2. The drill tip screw of claim 1, wherein the maximum tip width is at least 118%, 122% or 126% of the root diameter.

3. The drill tip screw of claim 1 or claim 2, wherein the maximum tip width is less than 131% of the root diameter.

4. The drill tip screw of any one of the preceding claims, wherein the maximum tip width is at least 73%, 77%, 79% or 82% of the major diameter.

5. The drill tip screw of any one of the preceding claims, wherein the maximum tip width is less than 89% of the major diameter.

6. The drill tip screw of any one of the preceding claims, wherein the threaded portion includes a secondary or low thread starting at the drill tip and extending towards the head to define in combination with the major thread a high/low thread, the low thread having a low thread diameter less than the major thread diameter.

7. The drill tip screw of claim 6, wherein the maximum tip width is at least 89%, 94%, 97% or 100% of the low thread diameter.

8. The drill tip screw of claim 6 or claim 7, wherein the maximum tip width is less than 108% of the low thread diameter.

9. The drill tip screw of any one of the preceding claims, wherein the two angled blades are diametrically opposed primary blades and the drill tip further comprises two diametrically opposed, secondary angled blades orientated perpendicular to the primary blades.

10. The drill tip screw of any one of the preceding claims, wherein the drill tip is a spear point tip.

11. The drill tip screw of any one of claims 1 to 8, wherein the drill tip is a self-drilling drill tip.

12. The screw of any one of the preceding claims, further comprising a second threaded portion including a top thread starting at the head and extending towards the drill tip.

13. The screw of any one of the preceding claims, wherein the major thread is formed with a plurality of swarf indents, the plurality of swarf indents forming at least one swarf channel.

14. The screw of claim 13, wherein the at least one swarf channel is coextensive with the major thread.

15. The screw of claim 13 or 15, wherein the plurality of swarf indents are equi-spaced from one another every 180, 120, or 900 along the major thread depending on the number of swarf indents or swarf channels.

16. The screw of any one of claims 13 to 15, wherein each swarf indent is offset from an adjacent swarf indent.

17. The screw of any one of the preceding claims, wherein the head has a tool engaging formation.

18. The screw of claim 17, wherein the tool engaging formation is one of a Torx recess, a hex recess, a square recess, a Phillips recess, a spanner recess, a tri-wing recess, a clutch recess, a one-way recess, a Phillips-slot combination, and a square-slot combination.

19. The screw of any one of the preceding claims, wherein the head is one of a bugle head, a dome or contour head, and a truss head.

20. The screw of any one of the preceding claims, wherein an underside of the head has a plurality of ribs.