AU2003283128B2 - Metal machining and drilling bits - Google Patents
Metal machining and drilling bits Download PDFInfo
- Publication number
- AU2003283128B2 AU2003283128B2 AU2003283128A AU2003283128A AU2003283128B2 AU 2003283128 B2 AU2003283128 B2 AU 2003283128B2 AU 2003283128 A AU2003283128 A AU 2003283128A AU 2003283128 A AU2003283128 A AU 2003283128A AU 2003283128 B2 AU2003283128 B2 AU 2003283128B2
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- AU
- Australia
- Prior art keywords
- chuck
- shank
- wasted
- rotary bit
- safety
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Drilling Tools (AREA)
Description
WO 2004/050282 PCTiAU2003!001591 1 METAL MACHINING AND DRILLING BITS TECHNICAL FIELD OF THE INVENTION THIS invention concerns twist drills, router bits and like components which are normally held in three jaw chucks.
BACKGROUND TO THE INVENTION For both machining work and jobbing work the shanks of such bits are cylindrical and they rely on the operator tightening the chuck jaws to grip the shank firmly enough to impart the necessary torque. When unexpected hardness in the substrate is met, the bit may bind in the bore slowing the bit while the chuck may continue to spin. This interrupts the drilling operation and damages the bit.
Tradesmen commonly dispense with the chuck key when tightening a bit in the chuck, preferring to insert the required bit and then to grip the chuck briefly as it starts, using the torque of the drill to tighten the chuck. This helps to change bits quickly but chuck slip is common with such practice.
Spade bits have a single flat ground into the end 10 omm of the shank, but to improve grip this is intended to be placed adjacent a chuck jaw so that one jaw will close parallel to the flat.
Other drill bits are known that employ flats along the drill shank.
WO 02/064295 describes in combination a mounting portion of tool and a corresponding shank, the mounting portion of the holder has a ball-detent and the shank has a corresponding a circumferential groove where the circumferential groove is closely spaced from the insert end of the shank.
2
O
O US Patent Number 5, 466, 100 describes a drill bit having a stepped Sconstruction, referred to as a cone drill, and a quick change capability provided by a shank having a non-circular cross-section and a circumferential groove for quick connect-disconnect in a power tool or drill. The cone drill has a circumferential 00 groove close to the end of this is used as a reference point to enable an operator to 0 select the particular hole diameter being drilled.
00 M However, all these known bits are prone to jam and hence create a safety 0 N risk for an operator. It is an object of the present invention to reduce this safety risk.
OUTLINE OF THE INVENTION In one aspect therefore the invention provides a rotary bit with a shank adapted to locate in a chuck, the shank having an insert end and an end section extending from the insert end, the end section having at least one elongate flat which locates inside the chuck when the shank is operatively engaged in the chuck, and a wasted safety section spaced from the insert end by a spacing, the spacing of the wasted safety section from the insert end being sufficientso that when the shank is operatively engaged in the chuck, the wasted safety section is outside the chuck, the wasted safety section having a predetermined shear torque rating so that the shank shears at the wasted safety section if the predetermined shear torque rating is exceeded, the shank includes a further flat outboard of the wasted safety section so that after the wasted safety section has been sheared, if necessary, a user may still use the bit on a temporary basis to complete a drilling task.
Preferably, the shear torque rating at which the wasted safety section shears is in the range 15-30 ft lbs.
t 3 0 O Preferably, the shear torque rating at which the wasted safety section shears is in the range 15-20 ft lbs.
Preferably, the shear torque rating at which the wasted safety section shears is in the range 25-30 ft lbs.
00 S 5 Preferably, the shank includes circumferentially spaced longitudinally O0 extending flats which locate inside the chuck when the shank is operatively M engaged in the chuck.
0 N Preferably, the shank includes multiple longitudinally extending flats which locate inside the chuck when the shank is operatively engaged in the chuck.
Preferably, the shank has a regular polygonal section including multiple longitudinally extending flats which locate inside the chuck when the shank is operatively engaged in the chuck.
Preferably, the shank includes circumferentially spaced longitudinally extending flats which locate inside the chuck when the shank is operatively engaged in the chuck and there being matching flats outboard of the wasted safety section so that after the wasted safety section has been sheared, if necessary, a user may still use the bit on a temporary basis to complete a drilling task.
Preferably, the shank includes multiple longitudinally extending flats which locate inside the chuck when the shank is operatively engaged in the chuck and there being matching flats outboard of the wasted safety section so that after the wasted safety section has been sheared, if necessary, a user may still use the bit on a temporary basis to complete a drilling task.
WO 2004/050282 PCT/AU20031001591 4 Preferably, the shank has a regular polygonal section including multiple longitudinally extending flats which locate inside the chuck when the shank is operatively engaged in the chuck and there being matching flats outboard of the wasted safety section so that after the wasted safety section has been sheared, if necessary, a user may sti ll use the bit on a temporary basis to complete a drilling task.
Preferably, the rotary bit is a coded one of a coded set of safety bits, the code being according to the shear torque rating and risk factor associated with the type of drill being used.
Preferably, the rotary bit is a coded one of a coded set of safety bits, the code of each bit in the set being according to the shear torque rating and risk factor associated with the type of drilling activity being undertaken.. The shank typically has three, six, nine or twelve flats arranged on the insert end of the shank in order to present a surface with is parallel to each jaw of the three jaw chuck.
The shear torque is typically 15-30 ft Ibs. Preferably 15-20 ft Ibs for domestic drills and 20-30 ft Ibs for industrial drills.
When six, nine or twelve flats are present, the flats may be contiguous.
When three flats are provided these may be mutually separated by arcuate portions of the shank in order to retain a substantial proportion of the section of the shank for taking the rotational force of the chuck. The flats and the arcuate separation of the flats may be of substantially equal sectors.
The flats may be machined, ground, or formed during manufacture.
WO 2004/050282 PCT/AU20031001591 Theoretically the best resistance to slippage occurs when there is a flat which mates with a closing jaw. Friction is independent of contact area and depends only upon the closing force and the coefficient of friction between the jaw and the shank. The shank is normally polished and therefore prone to slip, but the displacement of the jaw must occur before the shank can slip. Once flats have been provided on the shank physical displacement of the jaw is prevented. This ensures that chuck and shank rotate at the same speed rather than reliance upon friction.
Twelve seems to be the upper limit because a greater number begins to approximate to a circular section which is the cause of the slippage.
BRIEF DESCRIPTION OF THE DRAWINGS Certain embodiments of the invention are now described with reference to the accompanying drawings in which:- Figure 1 is an end view of a partially open chuck; Figure 2 is a larger scale section of a shank with six flats; Figure 3 is a section of a shank with three flats; Figure 4 is a section showing a shear off safety feature applicable to the present invention; and Figure 5 is a graphical representation of torque in foot pounds against shear width in millimetres showing a range of widths suited to different applications.
METHOD OF PERFORMANCE Referring to Figure 1 the three jaws 2 define a triangular space 4 into which the shank of a twist drill is inserted. In Figure 2 the flats 6 are ground in the insert WO 2004/050282 PCT/AU20031001591 6 end of an HSS shank 8 held in a tool head 10 which indexes. The flats produce a shank of hexagonal section.
In Figure 3 the flats 6 are ground on three equi-spaced sectors of the shank diameter. The arc 12 between the flats are equal in distance to the width of the flats.
The drill includes a shear off safety feature. An example is shown in Figure 4 at 20 where the flats 21 as previously described are connected to the bit 22 via a wasted section 23 so that upon jamming of the bit in a workpiece the wasted section will twist and shear off releasing the operator. It will be appreciated that the shank of the bit is made long enough that even if it is sheared there is still enough shank so that the drill may still be used to complete a drilling procedure if this be required. However this would not be the safest approach.
Applicant envisages torque safety settings dependent upon the level of skill or strength of an operator, the nature of the driving tool and the type of use. For example, household use might be divided into home use or handyman use, industrial use might be divided into light industrial and heavy industrial. The risks involved will vary and hence the torque safety level will vary as well.
Figure 5 shows the preferred torque settings for different applications, the shaded region from 15 ft Ib torque to 20 ft Ib torque is typical for a domestic hand drill whereas the 25 ft Ib torque to 30 ft Ib torque is preferred for larger industrial drills in industrial applications. The "jobber" bit is a lower quality steel than the HSS which refers to "high speed steel" rated bits. Consequently for most applications the wasted section will be between 5 mm and 7mm. Having said this it is preferred that WO 2004/050282 PCT/AU20031001591 7 drill bits be colour coded in sets and a recommended coded drill bits for different applications so that the operator may know the safest drill bit for the particular application. For example, it may be desirable to select a lower shear width for situations where the operator is involved with overhead drilling as opposed to a more stable drilling position where the risk factor associated with a drill being jammed is less due to greater control of the drill is less awkward situations..
Applicant recommends a safety rating of 20%-30% lower shear torque for overhead drilling than for horizontal applications. Thus for overhead applications in an industrial drill the code would be at the lower end of graph Figure In terms of Figure 5, the lowest torque setting could be 5 ft Ibs for a hand held drill set that might be used occasionally by an inexperienced user. The upper level may be as high as 40 ft Ibs in cases such as a drill press where risk of movement of the workpiece being drilled is the higher. On the other hand wrist injuries might be the higher risk for hand held pistol grip drills and a lower setting would apply. Thus, four sets of drill bits may be purchased, these may be coded by a coloured filler in the wasted section. Yellow might correspond to general household and have the lowest torque setting, green to homrne handyman, blue to light industrial and red to heavy industrial and so on as the torque setting increases.
Whilst the above has been given by way of illustrative example of the present invention many variations and modifications thereto will be apparent to those skilled in the art without departing from the broad ambit and scope of the invention as set out in the appended claims.
Claims (32)
1. A rotary bit with a shank adapted to locate in a chuck, the shank having an insert end and an end section extending from the insert end, the end section having at least one elongate flat which locates inside the chuck when the shank is 00 N 5 operatively engaged in the chuck, and a wasted safety section spaced from the 00 insert end by a spacing, the spacing of the wasted safety section from the insert end obeing sufficient so that when the shank is operatively engaged in the chuck, the N wasted safety section is outside the chuck, the wasted safety section having a predetermined shear torque rating so that the shank shears at the wasted safety section if the predetermined shear torque rating is exceeded, wherein the shank includes a further flat outboard of the wasted safety section so that after the wasted safety section has been sheared, if necessary, a user may still use the bit on a temporary basis to complete a drilling task.
2. A rotary bit according to Claim 1 wherein the shear torque rating at which the wasted safety section shears is in the range 15-30 ft Ibs.
3. A rotary bit according to Claim 1 wherein the shear torque rating at which the wasted safety section shears is in the range 15-20 ft lbs.
4. A rotary bit according to Claim 1 wherein the shear torque rating at which the wasted safety section shears is in the range 25-30 ft lbs.
5. A rotary bit according to Claim 1 wherein the shank includes circumferentially spaced longitudinally extending flats which locate inside the chuck when the shank is operatively engaged in the chuck. ~9 O O
6. A rotary bit according to Claim 1 wherein the shank includes multiple longitudinally extending flats which locate inside the chuck when the shank is ON operatively engaged in the chuck.
7. A rotary bit according to Claim 1 wherein the shank has a regular polygonal 00 S 5 section including multiple longitudinally extending flats which locate inside the 00 chuck when the shank is operatively engaged in the chuck.
8. A rotary bit according to Claim 1 wherein the shank includes circumferentially spaced longitudinally extending flats which locate inside the chuck when the shank is operatively engaged in the chuck and there being matching flats outboard of the wasted safety section so that after the wasted safety section has been sheared, if necessary, a user may still use the bit on a temporary basis to complete a drilling task.
9. A rotary bit according to Claim 1 wherein the shank includes multiple longitudinally extending flats which locate inside the chuck when the shank is operatively engaged in the chuck and there being matching flats outboard of the wasted safety section so that after the wasted safety section has been sheared, if necessary, a user may still use the bit on a temporary basis to complete a drilling task. A rotary bit according to Claim 1 wherein the shank has a regular polygonal section including multiple longitudinally extending flats which locate inside the chuck when the shank is operatively engaged in the chuck and there being matching flats outboard of the wasted safety section so that after the wasted safety O O section has been sheared, if necessary, a user may still use the bit on a temporary basis to complete a drilling task.
ON
11. A rotary bit according to Claim 1 wherein the rotary bit is a coded one of a coded set of safety bits, the code being according to the shear torque rating and risk 00 N 5 factor associated with the type of drill being used. 00
12. A rotary bit according to Claim 1 wherein the rotary bit is a coded one of a ocoded set of safety bits, the code of each bit in the set being according to the shear 0 N, torque rating and risk factor associated with the type of drilling activity being undertaken.
13. A rotary bit according to Claim 1 wherein the shank includes circumferentially spaced longitudinally extending flats which locate inside the chuck when the shank is operatively engaged in the chuck and the shear torque rating at which the wasted safety section shears is in the range 15-30 ft Ibs.
14. A rotary bit according to Claim 1 wherein the shank includes multiple longitudinally extending flats which locate inside the chuck when the shank is operatively engaged in the chuck and the shear torque rating at which the wasted safety section shears is in the range 15-30 ft Ibs.
A rotary bit according to Claim 1 wherein the shank has a regular polygonal section including multiple longitudinally extending flats which locate inside the chuck when the shank is operatively engaged in the chuck and the shear torque rating at which the wasted safety section shears is in the range 15-30 ft lbs.
16. A rotary bit according to Claim 1 wherein the rotary bit is a coded one of a coded set of safety bits, the code being according to the shear torque rating and risk O O factor associated with the type of drill being used and the shear torque rating at which the wasted safety section shears is in the range 15-30 ft Ibs.
17. A rotary bit according to Claim 1 wherein the rotary bit is a coded one of a c-l coded set of safety bits, the code of each bit in the set being according to the shear 00 Cl torque ratingand risk factor associated with the type of drilling activity being 00 undertaken and the shear torque rating at which the wasted safety section shears is oin the range 15-30 ft lbs. l
18. A rotary bit according to Claim 1 wherein the shank includes circumferentially spaced longitudinally extending flats which locate inside the chuck when the shank is operatively engaged in the chuck and the shear torque rating at which the wasted safety section shears is in the range 25-30 ft lbs.
19. A rotary bit according to Claim 1 wherein the shank includes multiple longitudinally extending flats which locate inside the chuck when the shank is operatively engaged in the chuck and the shear torque rating at which the wasted safety section shears is in the range 25-30 ft lbs.
A rotary bit according to Claim 1 wherein the shank has a regular polygonal section including multiple longitudinally extending flats which locate inside the chuck when the shank is operatively engaged in the chuck and the shear torque rating at which the wasted safety section shears is in the range 15-30 ft lbs.
21. A rotary bit according to Claim 1 wherein the rotary bit is a coded one of a coded set of safety bits, the code being according to the shear torque rating and risk factor associated with the type of drill being used and the shear torque rating at which the wasted safety section shears is in the range 25-30 ft Ibs. 12 O O
22. A rotary bit according to Claim 1 wherein the rotary bit is a coded one of a coded set of safety bits, the code of each bit in the set being according to the shear ON torque rating and risk factor associated with the type of drilling activity being undertaken and the shear torque rating at which the wasted safety section shears is 00 N in the range 25-30 ft lbs. 00
23. A rotary bit according to Claim 1 wherein the shank includes o circumferentially spaced longitudinally extending flats which locate inside the N chuck when the shank is operatively engaged in the chuck and the shear torque rating at which the wasted safety section shears is in the range 15-20 ft lbs.
24. A rotary bit according to Claim 1 wherein the shank includes multiple longitudinally extending flats which locate inside the chuck when the shank is operatively engaged in the chuck and the shear torque rating at which the wasted safety section shears is in the range 15-20 ft lbs.
A rotary bit according to Claim 1 wherein the shank has a regular polygonal section including multiple longitudinally extending flats which locate inside the chuck when the shank is operatively engaged in the chuck and the shear torque rating at which the wasted safety section shears is in the range 15-20 ft lbs.
26. A rotary bit according to Claim 1 wherein the rotary bit is a coded one of a coded set of safety bits, the code being according to the shear torque rating and risk factor associated with the type of drill being used and the shear torque rating at which the wasted safety section shears is in the range 15-20 ft lbs.
27. A rotary bit according to Claim 1 wherein the rotary bit is a coded one of a coded set of safety bits, the code of each bit in the set being according to the shear O O torque rating and risk factor associated with the type of drilling activity being undertaken and the shear torque rating at which the wasted safety section shears is in the range 15-20 ft lbs.
28. A rotary bit according to Claim 1 wherein the shear torque rating at which 00 C, the wasted safety section shears is in the range 5-40 ft lbs. en3 00
29. A rotary bit according to Claim 1 wherein the shank includes multiple o longitudinally extending flats which locate inside the chuck when the shank is C, operatively engaged in the chuck and the shear torque rating at which the wasted safety section shears is in the range 5-40 ft lbs.
A rotary bit according to Claim 1 wherein the shank has a regular polygonal section including multiple longitudinally extending flats which locate inside the chuck when the shank is operatively engaged in the chuck and the shear torque rating at which the wasted safety section shears is in the range 5-40 ft Ibs.
31. A rotary bit according to Claim 1 wherein the rotary bit is a coded one of a coded set of safety bits, the code being according to the shear torque rating and risk factor associated with the type of drill being used and the shear torque rating at which the wasted safety section shears is in the range 5-40 ft lbs.
32. A rotary bit according to Claim 1 wherein the shank has a regular polygonal section including multiple longitudinally extending flats which locate inside the chuck when the shank is operatively engaged in the chuck and the shear torque rating at which the wasted safety section shears is in the range 5-40 ft lbs.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2003283128A AU2003283128B2 (en) | 2002-11-29 | 2003-11-28 | Metal machining and drilling bits |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2002952999 | 2002-11-29 | ||
| AU2002952999A AU2002952999A0 (en) | 2002-11-29 | 2002-11-29 | Metal machining and drilling bits |
| AU2003283128A AU2003283128B2 (en) | 2002-11-29 | 2003-11-28 | Metal machining and drilling bits |
| PCT/AU2003/001591 WO2004050282A1 (en) | 2002-11-29 | 2003-11-28 | Metal machining and drilling bits |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU2003283128A1 AU2003283128A1 (en) | 2004-06-23 |
| AU2003283128B2 true AU2003283128B2 (en) | 2006-10-19 |
Family
ID=34378225
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU2003283128A Ceased AU2003283128B2 (en) | 2002-11-29 | 2003-11-28 | Metal machining and drilling bits |
Country Status (1)
| Country | Link |
|---|---|
| AU (1) | AU2003283128B2 (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1984003461A1 (en) * | 1983-03-04 | 1984-09-13 | Larry Scott | Drill bit |
| DE29700943U1 (en) * | 1997-01-21 | 1997-03-13 | Santowski, Reinhard, 35719 Angelburg | Rotating cutting tool |
-
2003
- 2003-11-28 AU AU2003283128A patent/AU2003283128B2/en not_active Ceased
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1984003461A1 (en) * | 1983-03-04 | 1984-09-13 | Larry Scott | Drill bit |
| DE29700943U1 (en) * | 1997-01-21 | 1997-03-13 | Santowski, Reinhard, 35719 Angelburg | Rotating cutting tool |
Also Published As
| Publication number | Publication date |
|---|---|
| AU2003283128A1 (en) | 2004-06-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FGA | Letters patent sealed or granted (standard patent) | ||
| PC | Assignment registered |
Owner name: SPINIFHEX GLOBAL HOLDINGS PTY LTD Free format text: FORMER OWNER WAS: MUGELI, DAVID REES |
|
| MK14 | Patent ceased section 143(a) (annual fees not paid) or expired |